NHS Choices

Vigorous exercise 'may help prevent early death'

NHS Choices - Behind the Headlines - Tue, 07/04/2015 - 13:00

"Short bursts of vigorous exercise helps prevent early death," The Independent reports after an Australian study found vigorous exercise, such as jogging, reduced the risk of premature death.

The study involved adults aged 45 to 75 years old followed up over 6.5 years. Those who did more vigorous activity (as part of their general total moderate to vigorous activity levels) were less likely to die during follow-up than those who did no vigorous activity.

This large study was well designed, and the researchers also tried to take factors into account that they knew could influence the results (confounders).

But, as with all studies, there are some limitations – for example, the researchers only asked about physical activity once and this may have changed over time.

These results also bear out the proven benefits of exercise, regardless of how much of it is vigorous, and supports current recommendations for the amount of physical activity people should do.

While doing some vigorous activity may bring some benefits, it is important that people set themselves realistic targets they can safely achieve.  

Where did the story come from?

The study was carried out by researchers from James Cook University and other universities in Australia. It was funded by the Heart Foundation of Australia.

The study was published in the peer-reviewed medical journal JAMA Internal Medicine.

The coverage in the papers is variable. While all the papers are right in saying that vigorous exercise may be beneficial, there is some misreporting. The Daily Telegraph's headline says that, "Swimming, gardening or golf 'not enough to prevent early death'," which is not true.

Gentle swimming and vigorous gardening both fell under "moderate activity", and even those who just did moderate activity had a lower risk of death than those who did no moderate to vigorous activity at all.

The Telegraph also talks about the effects on heart disease and diabetes, but these outcomes were not assessed by this study.

The Daily Express helpfully includes a quote noting that, "There is no question that some exercise is better than nothing. But the more intensive the activity, the less likely people will come back to it, so the question is how do we get people to do some – and then those who do some to do a bit more?"

However, at the end of the story, they then include a video of "chubby guy dancing in Speedos to holiday exercise class" for people's amusement, which is not likely to encourage people to take up exercise.

The Independent refers to "short bursts" of vigorous exercise being beneficial, but the study itself did not assess length of the bursts.

The paper does include a note of caution from one study author, however, who said that, "For those with medical conditions, for older people in general and for those who have never done any vigorous exercise before, it's always important to talk to a doctor first." 

What kind of research was this?

This was a prospective cohort study assessing whether achieving more moderate to vigorous activity through vigorous activity specifically was associated with a reduced risk of death during follow-up.

While we know that physical activity is associated with longer life, it is not clear whether vigorous activity is better than moderate activity.

While a recent systematic review suggested that vigorous activity may reduce the risk of death more than moderate activity, some of the studies included did not take overall activity into account.

This means these studies were not able to rule out that some of the effect of vigorous exercise was because people who did more vigorous activity tended to do more physical activity overall.

The current study wanted to avoid this problem. A prospective cohort study is the best way to assess this question. It's unlikely to be feasible to carry out a randomised controlled trial to successfully answer this question, as it's difficult to get people to agree to stick to a specific exercise pattern for a long time.

But the main limitation of a cohort study is that factors other than the factor of interest (such as overall activity, in this case) could potentially influence the results, so the researchers need to take these into account in their analyses. 

What did the research involve?

The researchers enrolled adults aged 45 and over from New South Wales. At the start of the study, participants were asked how much physical activity they did and how intense this activity was.

They were then followed up over about 6.5 years, and the researchers identified who died in this period.

The researchers then analysed whether the proportion of the total moderate to vigorous physical activity (MVPA) a person did that was vigorous was associated with their risk of death.

The participants were enrolled as part of the 45 and Up study in 2006-09. Potential participants were selected at random from the Australian national medical insurance (Medicare) database, which includes all citizens and permanent residents of the country.

This study did not include people aged over 75, as it was mainly interested in earlier preventable deaths.

Participants filled out a questionnaire at the start of the study on their MVPA in the past week. They were asked how much of this activity was:

  • vigorous – anything that "made you breathe harder or puff and pant", such as jogging, cycling, aerobics or competitive tennis, but not household chores or gardening
  • moderate – gentle swimming, social tennis, vigorous gardening or housework

Participants also reported how much walking they did, and this was included in their total MVPA.

Those who died between the start of the study and June 2014 were identified through the New South Wales Registry of Births, Deaths, and Marriages.

The main analyses in this study included 204,542 people who reported doing at least some MVPA. The researchers took factors that could affect the results (potential confounders) into account, including:

  • total MVPA
  • age
  • sex
  • educational level
  • marital status
  • area of  residence (urban or rural)
  • body mass index (BMI)
  • physical function (whether the person had any physical limitations)
  • smoking status
  • alcohol consumption
  • fruit and vegetable consumption  
What were the basic results?

During the study, 7,435 of the 217,755 participants died:

  • 8.3% of those who did no MVPA
  • 4.8% of those who did 10 to 149 minutes of MVPA a week
  • 3.2% of those who did 150 to 299 minutes of MVPA a week
  • 2.6% of those who did 300 minutes or more or MVPA a week

After taking potential confounders into account, this meant that compared with those who did no MVPA, the risk of death during the 6.5 years of follow-up was:

  • 34% lower in those who did 10 to 149 minutes of MVPA a week (hazard ratio [HR] 0.66, 95% confidence interval [CI] 0.61 to 0.71)
  • 47% lower in those who did 150 to 299 minutes of MVPA a week (HR 0.53, 95% CI 0.48 to 0.57)
  • 54% lower in those who did 300 minutes or more or MVPA a week (HR 0.46, 95% CI 0.43 to 0.49)

Among those who did at least some MVPA, doing more of that activity as vigorous activity was associated with a reduced risk of death during follow-up:

  • 3.8% of those who did no vigorous activity died
  • 2.4% of those who did vigorous activity that accounted for less than 30% of their total MVPA died – a 9% reduction relative to those who did none (HR 0.91, 95% CI 0.84 to 0.98)
  • 2.1% of those who did vigorous activity that accounted for 30% or more of their total MVPA died – a 13% reduction relative to those who did none (HR 0.87, 95% CI 0.81 to 0.93)

The researchers found similar results when they looked at people with different BMIs, people who did different amounts of MVPA, and in people with or without cardiovascular disease or diabetes.  

How did the researchers interpret the results?

The researchers concluded there was an "inverse dose-response relationship" between the proportion of MVPA done as vigorous activity and the risk of death during follow-up.

They say this suggests that vigorous activity "should be endorsed in clinical and public health activity guidelines to maximise the population benefits of physical activity". 

Conclusion

This large study suggests that in middle to older age, doing more of your total moderate to vigorous activity as vigorous activity could help to reduce your risk of death.

This study's size is one of its strengths, with more than 200,000 people taking part. The fact that information on activity was collected at the start of the study, rather than asking people to recollect what they did in the past, is also beneficial.

The researchers also tried to take factors into account that they knew could influence their results, including cardiovascular medical conditions such as coronary heart disease, or other conditions that reduced people's ability to participate in physical activity, such as type 2 diabetes.

But, as with all studies, there are some limitations:

  • The researchers only asked about physical activity once, and people's activities may have been different before or after the week that was assessed.
  • The study only included those aged 45 to 75, and results may not apply to older individuals.
  • All lifestyle measures were reported by the participants themselves, and there may be some inaccuracies – the authors state people tend to be better at reporting vigorous activity than other types of activity.
  • The results may still be influenced by confounders the authors did not measure –  for example, only fruit and vegetable intake was assessed as a sign of a healthy diet, but other dietary aspects could have had an effect.

While the results suggest that doing more vigorous activity is beneficial, there are some points to think about. For example, the people who were doing more vigorous activity may also have done more vigorous activity in their younger years, and it may be that this consistency is the important factor.

The study also did not directly compare just moderate activity with vigorous activity. Further research is likely to assess these and other questions.

Importantly, the results highlight the beneficial effect of doing some moderate to vigorous activity, regardless of how much of it is vigorous. This supports current recommendations for exercise.

While doing some vigorous activity may add some benefit, it is important that people set themselves realistic targets they can safely achieve.

If it has been a while since you last exercised, the NHS Choices Couch to 5K running programme is one way to safely raise your fitness levels.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Links To The Headlines

Short bursts of vigorous exercise helps prevent early death, says study. The Independent, April 6 2015

Swimming, gardening or golf 'not enough to prevent early death'. The Daily Telegraph, April 6 2015

How to live for longer: Brisk exercise slashes risk of early death. Daily Express, April 7 2015

Links To Science

Gebel K, Ding D, Chey T, et al. Effect of Moderate to Vigorous Physical Activity on All-Cause Mortality in Middle-aged and Older Australians. JAMA Internal Medicine. Published online April 6 2015

Categories: NHS Choices

Sedentary lifestyle – not watching TV – may up diabetes risk

NHS Choices - Behind the Headlines - Thu, 02/04/2015 - 16:31

“Experts claim being a couch potato can increase the risk of developing diabetes,”  the Daily Express reports.

A study of people at high risk of diabetes produced the sobering result that each hour of time spent watching TV increased the risk of type 2 diabetes by 2.1% (after being overweight was taken into account).

The study originally compared two interventions aimed at reducing the risk of developing diabetes compared to placebo. It involved 3,000 participants who were overweight, had high blood sugar levels and insulin resistance. These are early indications that they may be developing diabetes (often referred to as pre-diabetes). The interventions were either metformin (a drug used to treat diabetes) or a lifestyle intervention of diet and exercise.

This study used data collected from the original trial to see if there was a link between increased time spent watching the TV and risk of developing diabetes.

Across all of the groups they found a slightly increased risk, which was 3.4% per hour of TV watching when being overweight was not taken into account.

The findings may not be reliable, as researchers did not take other risk factors into account, such as family history of diabetes, use of other medication or smoking status. They also relied on self-reported TV watching times, which may not be very accurate.

That said, lack of exercise is a known risk factor for a range of chronic diseases – not just diabetes. Read more about why sitting too much is bad for your health.

 

Where did the story come from?

The study was carried out by researchers from the University of Pittsburgh, George Washington University, Pennington Biomedical Research Center and several other US universities. It was funded by many different US National Health Institutes and three private companies: Bristol-Myers Squibb, Parke-Davis and LifeScan Inc.

The main funding source was the National Institute of Diabetes and Digestive and Kidney Diseases of the US National Institutes of Health. One of the authors has a financial interest in a company called Omada, which develops online behaviour change programmes, with a focus on diabetes.

The study was published in the peer-reviewed medical journal Diabetologia.

The UK media has focused on the statistic that the risk of getting diabetes increases by 3.4% per hour of TV watched. However, this figure does not take into account the risk factor of being overweight. When this is accounted for, the increased risk is less, at 2.1%.

The Daily Express’s online headline "Watching too much TV can give you diabetes" would not be our preferred wording. Some readers may take it as a statement that their TV sends out dangerous rays that increase your blood sugar levels. A more accurate, if slightly less striking, headline would be "Sedentary behaviour increases your diabetes risk".

 

What kind of research was this?

This study looked at data from a randomised controlled trial that aimed to test whether lifestyle changes or the diabetes drug metformin reduced the risk of developing diabetes compared to placebo (dummy pill). It was conducted on over 3,000 people at high risk of diabetes. The trial found that metformin reduced the risk by 31% and that the lifestyle intervention reduced it by 58% compared to placebo.

This study aimed to see if the lifestyle intervention, which aimed to increase physical activity, had any effect in reducing the amount of self-reported time spent sitting. As a secondary outcome, the researchers looked at data from each group to see if there was an association between time spent sitting and the risk of diabetes. As this was not one of the aims of the study, the results of this type of secondary analysis are less reliable.

Critics of this approach argue that it is akin to "moving the goalposts"; researchers fail to get a striking result for their stated aim, so they then focus on a secondary aim that will get them the results.

 

What did the research involve?

Over 3,000 adults at high risk of diabetes were randomly allocated to take metformin, a placebo, or have a lifestyle intervention, from 1996 to 1999. They were followed up for an average of 3.2 years to see if any of the interventions reduced the risk of developing diabetes.

The lifestyle group had an "intensive" lifestyle intervention focusing on a healthy diet and exercise. The aim for this group was to achieve 7% weight loss and do at least 150 minutes of moderate intensity activity per week (the recommended minimal activity levels for adults). They were advised to limit inactive lifestyle choices, such as watching the TV. People given the metformin or placebo were also advised about a standard diet and had exercise recommendations. The study took place over 2.8 years.

A variety of measures were recorded, including weight and annual blood sugar tests. Each year, the participants were interviewed using a Modifiable Activity Questionnaire. This recorded self-reported estimates of leisure, TV watching and work-related activity.

In this analysis, the researchers compared the amount of time each person reported they spent watching the TV at the start and end of the study in each group.

 

What were the basic results?

Across all of the treatment groups, every hour per day of watching TV raised the risk of diabetes by 2.1%, after adjusting for age, sex, physical activity and weight. When the results did not take increased weight into account, the risk was higher, at 3.4% per hour.

By the end of the study, people in the lifestyle intervention group watched less TV. At the start of the study, each group reported watching a similar amount of TV – around 2 hours and 20 minutes per day. Three years later, people in the lifestyle group watched on average 22 minutes less per day. Those in the placebo group watched 8 minutes less, but those on metformin did not change their TV watching significantly.

 

How did the researchers interpret the results?

The researchers concluded that although it was not a primary goal of the study, "the lifestyle intervention was effective at reducing sedentary time". They report that "in all treatment arms, individuals with lower levels of sedentary time had a lower risk of developing diabetes". They advise that "future lifestyle intervention programmes should emphasise reducing television watching and other sedentary behaviours, in addition to increasing physical activity".

 

Conclusion

This study has found an association between TV watching and an increased risk of developing diabetes. However, there are many potential confounding factors that were not taken into account in the analysis. This includes other medical conditions, medication, family history of diabetes and smoking. 

Additionally, all of the participants were at high risk of developing diabetes. They were overweight at the start of the study, had high blood sugar levels and insulin resistance – therefore, the study does not show whether this association would be found in people at low or moderate risk.

The original study did not set out to see if increased TV watching was associated with increased risk of developing diabetes; this was an afterthought, using the data that had been collected. This makes the results less reliable.

A further limitation is that the study is reliant on self-reporting the amount of time spent watching TV. This was estimated for the previous year, which is unlikely to be entirely accurate.

Watching TV is not "going to give you diabetes" as the Express had confusingly stated, but it is important to compensate for time spent being a couch potato by exercising regularly, eating a healthy diet and trying to achieve or maintain a healthy weight.

Read more about reducing your type 2 diabetes risk

Analysis by Bazian. Edited by NHS ChoicesFollow Behind the Headlines on TwitterJoin the Healthy Evidence forum.

Links To The Headlines

Watching too much TV can give you diabetes, experts warn. Daily Express, April 2 2015

How watching TV can increase your risk of diabetes: Every hour spent slumped in front of the screen can raise chance of developing the condition by 3.4%. Mail Online, April 2 2015

Secret to cutting diabetes risk is to turn off your television says new research. Daily Mirror, April 1 2015

Every Hour Spent In Front Of The TV Could Increase Diabetes Risk, Study Warns. The Huffington Post, April 2 2015

Links To Science

Rockette-Wagner B, Edelstein S, Venditti EM, et al. The impact of lifestyle intervention on sedentary time in individuals at high risk of diabetes (zip file 206kb). Diabetologia. Published online April 1 2015

Categories: NHS Choices

Do I need to stretch before exercising?

NHS Choices - Live Well - Thu, 02/04/2015 - 15:30
Do I need to stretch before exercising?

From weekend warriors to elite athletes, we’re often told we should stretch before exercising but new research has cast doubt on this age-old practice.

Research suggests stretching before exercise is unlikely to reduce your risk of injury, improve your performance or prevent sore muscles.

But while it won’t necessarily do you any good, there’s no evidence that stretching before or after exercise will you any harm either.

The upshot is if you enjoy stretching or it is a staple in your exercise routine, there’s no reason to stop.

Read on to get a deeper understanding of the mechanics of stretching and work out just how much stretching you really need in your life.

What’s the point of stretching?

Stretching for sport and exercise improves flexibility, which increases the ability of a joint to move through its full range of motion, in other words, how far it can bend, twist and reach. Some activities such as gymnastics require more flexibility than others, such as running.

Different types of stretches

Static stretch: stretching a muscle to the point of mild discomfort and holding that position, typically for at least 30 seconds or longer.

Proprioceptive neuromuscular facilitation (PNF): methods vary but typically PNF involves holding a stretch while contracting and relaxing the muscle. 

Dynamic stretch: performing gentle repetitive movements, such as arm swings, where one gradually increases the range of motion of the movement but always remains within the normal range of motion. 

Ballistic or bouncing stretches: involves going into a stretch and performing bouncing or jerking movements to increase range of motion.

Most of the research on stretching has focussed on static stretching and there is less evidence on other forms of stretching.

What happens when we stretch?

While the exact mechanics of what happens are not fully understood, regular stretching is thought to increase flexibility both by making muscles more supple and by retraining the nervous system to tolerate stretching further. Flexibility from regular stretching gradually disappears once you stop stretching – typically after four weeks.

Dr Polly McGuigan, a lecturer in biomechanics from the University of Bath, says it’s unclear whether the increase in range of motion of a joint is due to physical changes in the muscles which control those joints, or just a greater tolerance to stretch. She says: “My feeling is that there must be some changes at the muscle-tendon unit level as just increasing tolerance would not have the scale of effect that can be seen with some stretching programmes.”

How much flexibility do I need?

It depends on your activity. The flexibility demands of a gymnast or a ballet dancer are clearly different to those of a runner. There is little to be gained for a jogger or runner from having the flexibility of a gymnast.

To generate power during exercise, the muscles and tendons store and release energy like a spring. Too much flexibility may reduce the muscle’s natural spring, which may be detrimental for activities involving running, jumping and sudden changes in direction, such as running, football or basketball. 

“However, too little flexibility may increase the risk of muscle strain injury as the muscles are unable to lengthen and absorb this energy,” says Dr Anthony Kay, Associate Professor of Biomechanics from the University of Northampton.

Does stretching prior to exercise affect performance?

Research suggests stretching before exercise makes your muscles weaker and slower, even though you might feel looser. “For most performances, this would be detrimental,” says Dr Ian Shrier, a sports medicine clinician and researcher and Associate Professor at the Department of Family Medicine, at Montreal’s McGill University.

However, stretching also increases your range of motion. “A ballerina might require stretching before performance to do a full split during the show,” says Dr Shrier. “Even though she is weaker, her performance will be improved.” 

Dr Kay, who was the lead author on one of the largest reviews on pre-performance stretching, believes the reduction in performance from pre-exercise stretching has been overstated. “It is likely that durations of stretch used in the warm-up routines of most recreational exercisers produce negligible and transient reductions in strength,” he says. 

Does stretching before exercising reduce the risk of injury?

The evidence strongly suggests that pre-exercise stretching does not reduce the risk of injury. Professor Rob Herbert, Senior Principal Researcher Fellow with Neuroscience Research Australia, took part in the three largest randomised trials of the effects of stretching, all of which concluded stretching had little or no beneficial effect on reduction in injury risk.

The most recent and largest of the three studies found “a hint” of an effect on reducing injuries like ligament tears, muscle tears, strains and sprains. But Prof Herbert cautioned, “If stretching does cut your odds of one of these types of injuries, it’s by only a very small amount.”

When do injuries occur?

Muscle injuries happen when the muscle is put under too much stress, typically when it is stretched under pressure, for instance, when lowering a heavy weight.

The injury occurs not because the muscle isn’t flexible enough but because the muscle isn’t producing enough force to support itself. A muscle might not produce enough force either because it is not strong enough or it didn’t contract at the right time for a particular movement.

Does stretching after exercise help reduce soreness?

There is no evidence that stretching helps to reduce or prevent a type of pain that can show up a day or two after exercising - also called delayed onset muscle soreness (DOMS).

A 2011 review by Prof Herbert found that “muscle stretching, whether conducted before, after, or before and after exercise, does not produce clinically important reductions in delayed-onset muscle soreness in healthy adults.”

Should I stretch before exercising?

Your decision to stretch or not to stretch should be based on what you want to achieve. “If the objective is to reduce injury, stretching before exercise is not helpful,” says Dr Shrier. Your time would be better spent by warming up your muscles with light aerobic movements and gradually increasing their intensity.

“If your objective is to increase your range of motion so that you can more easily do the splits, and this is more beneficial than the small loss in force, then you should stretch,” says Dr Shrier.

For most recreational exercisers, stretching before exercise is therefore a matter of personal preference. “If you like stretching, do it and if you don’t like stretching, don’t do it.” says Prof Herbert.

How should I warm-up?

The purpose of warming-up is to prepare mentally and physically for your chosen activity. A typical warm-up will take at least 10 minutes and involve light aerobic movements and some dynamic stretching that mimics the movements of the activity you’re about to perform.

“Gradually increasing the range of motion of these movements during the warm up will prepare the body for more intense versions of those movements during the sport itself,” says Dr McGuigan. This process will raise your heart rate and increase the blood flow to your muscles, thereby warming them up.

Warm muscles are less stiff and work more efficiently. Increased blood flow enables more oxygen to reach the muscles and produce energy. The warm-up also activates the nerve signals to your muscles which results in faster reaction times.  

Should I stretch after exercising?

There is some evidence that regular static stretching outside periods of exercise may increase power and speed as well as reduce injury. The best time to stretch is when the muscles are warm and pliable. This could be during a yoga or pilates class or just after exercising.

However there is very limited evidence about specifically stretching after exercise. Dr Shier says: “Since people tend not to set aside one time to stretch and one time for other activities, I recommend that they stretch after exercise.”

A post-exercise stretch will also help slow down your breathing and heart rate and bring the mind and body back to a resting state.

Categories: NHS Choices

New Down’s syndrome test more accurate than current screening

NHS Choices - Behind the Headlines - Thu, 02/04/2015 - 14:00

“Blood test for Down’s syndrome 'gives better results'," reports BBC News today. The test, which is based on spotting fragments of "rogue DNA", achieved impressive results in a series of trials.

A study of over 15,000 women found that the new blood test more accurately identifies pregnancies with Down's syndrome than the test currently used.

Down's syndrome is caused by having an extra chromosome (the packages of DNA containing information to grow and develop). The new test is able to detect small fragments of DNA from the baby floating about in the mother’s blood, called cell-free DNA (cfDNA).

This blood test measures the number of chromosomes in the mother’s blood, and from that it can see if there are any of these extra chromosomes.

The cfDNA test performed significantly better than the current test across a range of screening test measures for Down’s syndrome, but was not 100% accurate. Importantly, it had a much lower false positive rate than the current test; false positive is where a healthy baby is wrongly identified as having Down’s. A false positive result often leads to an unnecessary further diagnostic test that carries a small risk of causing a miscarriage.

The test is not yet available on the NHS, but it is being reviewed and a decision is expected later this year. It can be accessed privately at a cost of between £400 and £900.

 

Where did the story come from?

The study was carried out by researchers from the University of California, the Perinatal Diagnostic Center in San Jose, Sahlgrenska University Hospital in Sweden, and several other US institutions. It was funded by Ariosa Diagnostics and the Perinatal Quality Foundation.

The study was published in the peer-reviewed New England Journal of Medicine.

BBC News accurately reported on the study and provided expert opinion from both Great Ormond Street Hospital and the Down's Syndrome Association. Both organisations highlight the need for women to be given clear information about screening, so they can make an informed decision.

 

What kind of research was this?

This was a diagnostic study, which compared a new antenatal screening test with standard screening for three genetic conditions, including Down’s syndrome.

Normally, people have 23 pairs of chromosomes. However, in these three genetic conditions, there is an extra copy of one of the chromosomes. In Down’s syndrome, there is an extra chromosome 21 (trisomy 21); Edwards' syndrome has an extra chromosome 18 (trisomy 18); and Patau’s syndrome has an extra chromosome 13 (trisomy 13). In most cases, this happens by chance and isn’t inherited from the parents. This is why all mothers-to-be are offered screening to see whether this has happened.

Currently, all pregnant women in the UK are offered screening for these conditions, which involves a two-step process. The test offered depends on how far along the pregnancy is. Women between 11 and 14 weeks pregnant are offered a blood test plus an ultrasound scan, called a combined test. Women between 14 and 20 weeks of pregnancy are offered a different blood test. This is less accurate than the combined test.

If either of these tests indicates an increased risk of having a baby with Down’s, Edwards’ or Patau’s syndromes, the woman will be offered either chorionic villus sampling (CVS) or amniocentesis to find out. Both of these tests involve taking samples from the mother’s abdomen, which can be uncomfortable, although not usually painful. This increases the risk of miscarriage, which occurs in one in 100 women (1%).

The new test detects short fragments of the baby’s DNA floating about in the mother’s blood, called cell-free DNA (cfDNA). By measuring the level of each of the chromosomes, it is possible to see if there are more chromosomes 21, 18 or 13.

The researchers had previously performed proof of principle studies of cfDNA in women at high risk of having a baby with one of these conditions. They now wanted to see how accurate the test was in a large sample of women with any level of risk.

 

What did the research involve?

The researchers recruited 15,841 pregnant women eligible for screening for Down’s, Edwards’ or Patau’s syndromes. All were tested using the new cfDNA blood test and the standard combined test. The results of the two tests were compared to see which was more accurate at picking up any of the three trisomy conditions.

Women were enrolled in the study between March 2012 and April 2013 from 35 medical centres across the US, Canada and Europe. They were eligible to participate if they were aged 18 or older, and had a singleton pregnancy between weeks 10 and 14.3 at the time of screening.

A blood test for cfDNA was taken at the same time as the standard screening tests. The blood sample was then analysed at a laboratory without the analysts knowing any clinical details about the pregnancy, other than the gestational age and mother’s age (the sample was blinded). The results were not given to the mother or clinician.

The researchers then obtained the outcome of the pregnancy and compared the accuracy of the standard test results with the new cfDNA test. This included any termination of pregnancies and miscarriages if a genetic test had confirmed whether or not they had a trisomy condition.

They originally enrolled 18,955 women, but excluded 3,114, due to:

  • them not meeting the inclusion criteria
  • withdrawal from the study (either the woman or the investigator)
  • sample handling errors
  • no standard screening result
  • no cfDNA result
  • lost to follow-up

 

What were the basic results?

The new test outperformed the current one at detecting Down’s syndrome. Results were similar for Edwards' and Patau’s syndromes, but tended to be less accurate.

One of the most important measures for whether a new screening test is any good is the positive predictive value (PPV). This takes into account the number of correct test results, but also the number of false positives, based on the condition's prevalence.

In rare conditions, like these chromosomal conditions, the false positives are important, because they represent a potentially large group of women who could be sent to have further invasive diagnostic tests they might not need.

The PPV of the new test for Down’s syndrome was 80.9% – significantly higher than the 3.4% scored for the combined test. The PPV difference was lower for women deemed at lower risk of having a baby with Down’s syndrome (76.0% for the new test v 50.0% for the current test).

The detailed results for Down’s syndrome (trisomy 21) were:

  • cfDNA screening identified all 38 babies with Down’s syndrome (sensitivity 100%, 95% confidence interval (CI) 90.7 to 100)
  • standard screening identified 30 out of 38 babies with Down’s syndrome (sensitivity 78.9%, 95% CI 62.7 to 90.4)
  • the cfDNA test was positive in nine pregnancies that did not have Down’s syndrome (false positive rate 0.06%, 95% CI 0.03 to 0.11)
  • standard screening was positive in 854 pregnancies that did not have Down’s syndrome (false positive rate 5.4% (95% CI 5.1 to 5.8)

Results for Edwards' syndrome (trisomy 18) were:

  • cfDNA identified nine out of 10 cases (sensitivity 90%, 95% CI 55.5 to 99.7)
  • standard testing identified eight out of 10 (sensitivity 80%, 95% CI 44.4 to 97.5)
  • cfDNA wrongly diagnosed Edwards' syndrome in one case (false positive rate 0.01%, 95% CI 0 to 0.04)
  • standard testing was positive in 49 pregnancies that did not have Edwards' syndrome (false positive rate 0.31%, 95% CI 0.23 to 0.41)

The results for Patau’s syndrome (trisomy 13) were:

  • cfDNA screening identified both babies (sensitivity 100%,95% confidence interval (CI) 15.8 to 100)
  • standard screening identified one out of the two babies (sensitivity 50.0%, 95% CI 1.2 to 98.7)
  • the cfDNA test was positive in two pregnancies that did not have Patau’s syndrome (false positive rate 0.02%, 95% CI 0 to 0.06)
  • standard screening was positive in 28 pregnancies that did not have Patau’s syndrome (false positive rate 0.25% (95% CI 0.17 to 0.36)

 

How did the researchers interpret the results?

The researchers concluded that "the performance of cfDNA testing was superior to that of traditional first trimester screening for the detection of trisomy 21". They say that further cost benefit studies are now needed. The researchers also caution that "as emphasised by professional societies, the use of cfDNA testing and other genetic tests requires an explanation of the limitations and benefits of prenatal test choices to the patient".

 

Conclusion

This large study has shown that the new cfDNA test is better than current standard screening at detecting three trisomy conditions during pregnancy. The confidence in accurately identifying affected pregnancies was strongest for Down’s syndrome. There were much wider confidence intervals for the other two conditions.

The cfDNA test was not 100% accurate, as there were false positive results for each condition, though much fewer than with standard screening.

Around 3% of the cfDNA tests did not produce a result. Careful consideration and further research may be needed to decide the best approach in these cases. Should they all be sent for the next stage of diagnostic tests as a precaution, repeat the test, or be offered the standard test instead? 

The author’s admit that, had they included these "no result" cases in their main analysis, the performance of the cfDNA test would have been lower. How much lower we don’t know, as they don’t appear to have presented an analysis of this scenario.

The potential benefit of the test is that it could reduce the number of women being sent for the CVS or amniocentesis testing, which carry their own risks. As the authors say: "Before cfDNA testing can be widely implemented for general prenatal aneuploidy screening, careful consideration of the screening method and costs is needed."

This test is not yet available on the NHS, though it is being considered under an evaluation project run by Great Ormond Street Hospital. In the evaluation study, which is being carried out on women at low risk, if the results of the test show that a trisomy is highly likely or it is inconclusive, then they are offered the invasive tests to confirm the result. This is because of potential false positive results, which in previous research was found to occur in one in 300 women (0.3%) and false negative results – not picking up the diagnosis in two out of 100 babies.

At present, the test is only offered by private clinics and costs £400 to £900. It takes two weeks to get the result, as the sample is sent to the US. Details of private clinics can be easily found via any internet search engine.

Analysis by Bazian. Edited by NHS ChoicesFollow Behind the Headlines on TwitterJoin the Healthy Evidence forum.

Links To The Headlines

Blood test for Down's syndrome 'gives better results'. BBC News, April 1 2015

Links To Science

Norton ME, Jacobsson B, Swamy GK, et al. Cell-free DNA Analysis for Noninvasive Examination of Trisomy. The New England Journal of Medicine. Published online April 1 2015

Categories: NHS Choices

Concerns raised about increased e-cigarette use in teenagers

NHS Choices - Behind the Headlines - Wed, 01/04/2015 - 13:30

"E-cigarettes: Many teenagers trying them, survey concludes," BBC News reports after a survey of around 16,000 English teenagers found one in five teens had tried an e-cigarette.

The concern is that rather than using e-cigarettes as a device to stop smoking, teenagers with no history of smoking could be using e-cigarettes because of their novelty value. This hypothesis seems to be borne out by the survey finding that 16% of teen e-cig users said they had never smoked conventional cigarettes.

While e-cigarettes are undoubtedly far safer than cigarettes, this does not mean they are 100% safe. Nicotine is a powerful substance and it is unclear what long-term effects it may have, especially on a teenage brain and nervous system that is still developing.

The study also found a strong association between alcohol misuse, such as binge drinking, and access to e-cigarettes. Other experts fear e-cigs could act as a potential gateway to smoking among children.

From 2016, the Medicines and Healthcare Products Regulatory Agency (MHRA) is expected to license e-cigarettes as a medicine in the UK, so they should become an age-restricted product.

One limitation of the study, however, is that it relied on self-reporting, so it is prone to selection bias. This makes its findings less reliable.

One final message you may want to convey to your children is that a nicotine addiction brings no useful benefits, but it can be expensive (especially for a teenager) and its long-term effects are unclear. 

Where did the story come from?

The study was carried out by researchers from Liverpool John Moores University, Public Health Wales, Health Equalities Group, and Trading Standards North West.

It was published in the peer-reviewed journal BMC Public Health. BMC Public Health is an open-access journal, so the study is free to read online.

It was covered broadly accurately in the papers, although reports focused on the number of non-smokers who had reportedly used e-cigarettes.

This raised fears in the press that the devices may become a gateway drug to tobacco, rather than concerns about the number of young smokers who reported using them.

The study's limitations, such as the issue of selection bias (which could either lead to an over- or underestimation of the true figure) and the fact the sample may not be representative of England, were not discussed.  

What kind of research was this?

This was a cross-sectional survey of more than 16,000 school students in northwest England looking at reported use of e-cigarettes, conventional smoking, alcohol consumption and other factors.

The authors say that while e-cigarettes are marketed as a healthier alternative to tobacco, they contain the addictive drug nicotine.

The battery-powered devices, which can be bought online and in some pubs, chemists and newsagents, deliver a hit of addictive nicotine and emit water vapour to mimic the feeling and look of smoking.

The vapour is considered potentially less harmful than cigarette smoke and is free of some of its damaging substances, such as tar. 

What did the research involve?

The researchers used a cross-sectional survey of 16,193 school students aged 14 to 17 in northwest England. This is part of a biennial survey conducted in partnership with Trading Standards, whose remit includes enforcing regulations on the sale of age-restricted products in the UK.

The survey includes detailed questions on:

  • age
  • gender
  • alcohol use (drinking frequency, binge drinking frequency, drink types consumed, drinking location, drinking to get drunk)
  • smoking behaviours (smoking status, age of first smoking)
  • how alcohol and tobacco were accessed
  • parental smoking
  • involvement in violence when drunk

In 2013, the survey included a question about e-cigarettes for the first time, asking students if they had ever tried or bought them.

The questionnaire was given to students by teachers during normal school lessons between January and April 2013. Students completed the questionnaire themselves voluntarily and anonymously. The researchers excluded questionnaires where data was incomplete or spoiled.

The researchers also collected information on deprivation using both home and school postcodes and assigning participants to five different groups (or quintiles). They used standard statistical methods to analyse associations between e-cigarette access and other factors. 

What were the basic results?

The main findings are summarised below:

  • one in five children (19.2%) who responded said they had "accessed" e-cigarettes
  • over one-third (35.8%) of those who reported accessing e-cigarettes were regular smokers, 11.6% smoked when drinking, 13.6% were ex-smokers, and 23.3% had tried smoking but didn't like it
  • 15.8% of teenagers who accessed e-cigarettes had never smoked conventional cigarettes
  • e-cigarette access was also associated with being male, having parents or guardians that smoke, and students' alcohol use
  • compared with non-drinkers, teenagers who drank alcohol at least weekly and binge drank were more likely to have accessed e-cigarettes (adjusted odds ratio [AOR] 1.89)
  • the link between e-cigarettes and alcohol was particularly strong among those who had never smoked tobacco (AOR 4.59)
  • among drinkers, e-cigarette access was related to drinking to get drunk, alcohol-related violence, consumption of spirits, self-purchase of alcohol from shops or supermarkets, and accessing alcohol by recruiting adult proxy purchasers outside shops  
How did the researchers interpret the results?

The researchers say their findings suggest e-cigarettes are being accessed by teenagers more for experimentation and as a recreational drug, rather than for help with smoking cessation.

There is an urgent need for controls on the promotion and sale of e-cigarettes to children, the researchers argue, although they also point out that those most likely to obtain e-cigarettes may already be familiar with "illicit methods" of accessing age-restricted substances. 

Conclusion

As the authors point out, this cross-sectional survey had a number of limitations:

  • it did not record how frequently e-cigarettes were reportedly accessed
  • it cannot tell us whether children who reported both conventional smoking and e-cigarette access had accessed e-cigarettes before or after using conventional cigarettes
  • it is possible that, as the questionnaire was voluntary, it suffered from selection bias, with only certain students completing it
  • students may have under- or over-reported their smoking and drinking behaviours

The survey should not be considered representative of all 14- to 17-year-olds in England or in the northwest. However, the finding that one in five children reported having access to e-cigarettes, and that many of them are non-smokers, is a clear cause for concern.

From 2016, the Medicines and Healthcare Products Regulatory Agency (MHRA) is expected to license e-cigarettes as a medicine in the UK. This should bring them in line with nicotine patches and gum, and allow the agency to apply rules around the purity of the nicotine in e-cigarettes, for example.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Links To The Headlines

E-cigarettes: Many teenagers trying them, survey concludes. BBC News, March 31 2015

Four in 10 teenage e-cigarette users would not have smoked, warn health experts. The Daily Telegraph, March 31 2015

Are teenagers trying e-cigarettes as a trendy novelty? ITV News, March 31 2015

E-cigarettes: why are young people vaping? Channel 4 News, March 31 2015

One in five teens have tried e-cigs: Fears youngsters will move on to real cigarettes after getting taste for nicotine. Mail Online, March 31 2015

Links To Science

Hughes K, Bellis MA, Hardcastle KA, et al. Associations between e-cigarette access and smoking and drinking behaviours in teenagers. BMC Public Health. Published online March 31 2015

Categories: NHS Choices

Paracetamol 'not effective' for lower back pain or arthritis

NHS Choices - Behind the Headlines - Wed, 01/04/2015 - 12:31

"Paracetamol doesn't help lower-back pain or arthritis, study shows," The Guardian reports on a new review.

The review found no evidence that paracetamol had a significant positive effect, compared to placebo (dummy treatment) in relieving pain and disability in cases of acute lower back pain and was only minimally effective in osteoarthritis.

Before you start clearing out your medicine cabinet, the results of this review are not as clear-cut as reported.

The findings for lower back pain are based on three randomised controlled trials (RCTs), which, when grouped together, found no difference for pain relief, disability or quality of life between paracetamol and placebo. However, there are limitations in each of these studies. Two of the studies were small and the third only looked at acute lower back pain up to six weeks, when paracetamol may not be strong enough.

They did actually find that paracetamol slightly improved pain and disability from osteoarthritis of the hip or knee compared to placebo.

The study does not prove that paracetamol is no better than placebo for other types of back pain, such as chronic back pain (pain that persists for more than six weeks).

The National Institute for Health and Care Excellence (NICE) recommends that people with persistent back pain and recurrent back pain should stay physically active to manage and improve the condition.

Paracetamol is recommended as a first choice of painkiller because it has few side effects. NICE recommends that if this is not effective, stronger or different types of painkillers should be offered.

This guidance is currently under review, and this will take into account any new research such as the results of this study.

 

Where did the story come from?

The study was carried out by researchers from the University of Sydney, St Vincent’s Hospital and University of New South Wales and Concord Hospital in Sydney. It was funded by the National Health and Medical Research Council.

The study was published in the peer-reviewed British Medical Journal (BMJ) on an open-access basis so is free to read online (PDF 673kb).

The UK media reported the story accurately but did not explain any of the limitations of the study.

 

What kind of research was this?

This was a systematic review of all RCTs assessing the effectiveness of paracetamol for back pain and osteoarthritis of the hip or knee compared to placebo. The researchers also performed a meta-analysis. This is a statistical technique that combines the results of the RCTs to give an overall measure of effectiveness.

Pooling the results of multiple studies can help to give a better estimate of effectiveness, which is sometimes not seen in the individual studies, for example if they are too small.

This type of research is good at summarising all the research on a question and calculating an overall treatment effect, but relies on the quality and availability of the RCTs.

Paracetamol is currently recommended as the first line for pain relief for back pain and osteoarthritis of the hip and knee in clinical guidelines. The researchers wanted to assess whether this recommendation is backed up by the evidence.

 

What did the research involve?

A systematic review and meta-analysis was performed to identify and pool all RCTs that have assessed paracetamol compared to placebo for back pain and osteoarthritis of the hip and knee.

The following medical databases were searched for RCTs published up until December 2014: Medline, Embase, AMED, CINAHL, Web of Science, LILACS, International Pharmaceutical Abstracts, and Cochrane Central Register of Controlled Trials. A search was also made for unpublished studies, and authors were contacted for further information where required.

Three reviewers selected all relevant RCTs that reported on any of the following outcomes:

  • pain intensity
  • disability status
  • quality of life

Trials were excluded where a specific serious cause of the back pain had been identified, such as a tumour or infection, if they looked at post-operative pain and studies of people with rheumatoid arthritis.

The quality of each RCT was assessed using the standardised approach called a "risk of bias" assessment. The strength of the body of evidence as a whole was summarised using the internationally recognised GRADE approach (The Grading of Recommendations Assessment, Development and Evaluation).

A meta-analysis was then performed to pool the results of trials in people with the different conditions using appropriate statistical methods. This included an analysis of whether the RCTs were similar enough to be combined. The researchers also performed "secondary exploratory analysis", which looks at the effect various different factors may have had in biasing the results.

 

What were the basic results?

The systematic review included 13 moderate- to high-quality RCTs and 12 of them in the meta-analysis:

  • three trials investigated short-term use of paracetamol for lower back pain (including 1,825 people)
  • 10 trials assessed paracetamol compared to placebo for osteoarthritis of the knee or hip (including 3,541 people)
  • no trials were found for neck pain

No significant difference was found between paracetamol and placebo in the short term control of lower back pain in terms of:

  • pain intensity
  • disability
  • quality of life

Paracetamol slightly improved pain and disability from osteoarthritis of the hip or knee compared to placebo.

People experienced a similarly small number of side effects when taking paracetamol or placebo. However, people taking paracetamol were four times more likely to have abnormal liver function tests than those taking placebo. The review did not describe how abnormal the tests were or how quickly the tests returned to normal after stopping paracetamol.

 

How did the researchers interpret the results?

The researchers concluded that "paracetamol is ineffective in the treatment of lower back pain and provides minimal short term benefit for people with osteoarthritis". They call for "reconsideration of recommendations to use paracetamol for patients with lower back pain and osteoarthritis of the hip or knee in clinical practice guidelines".

 

Conclusion

This systematic review and meta-analysis suggests paracetamol may not be effective for some people with lower back pain and of limited help to people with osteoarthritis of the hip and knee.

Strengths of the study include:

  • the systematic review only contained the "gold standard" type of trials – RCTs
  • existing published RCTs comparing paracetamol with a placebo were likely to have been identified, as a large number of databases were searched from the beginning of their records up to December 2014. There were also two independent reviewers, which reduces the risk of any slipping through the net
  • they also searched for unpublished studies, reducing the risk of publication bias in their results (trials are less likely to be published if their results do not show a clear benefit)
  • the quality of evidence was appropriately assessed

However, as noted above, this type of research is reliant on the availability of relevant RCTs.

So while the review itself was well-conducted, the actual body of new evidence found about lower back pain was small.

In this case, the results for back pain were limited to three studies in specific populations. Non-specific lower back pain (i.e. back pain without an obvious cause) is complex in nature and these small studies may not be representative of all people who experience lower back pain.

First study

The first study was small, of 36 adults on strong (opioid) painkillers for at least six months for chronic back pain. While on these painkillers they did not find any difference in pain between an injection into the vein of either paracetamol, placebo or the non-steroidal anti-inflammatory drugs (NSAID) diclofenac and parecoxib.

Second study

The second study assessed the effect of paracetamol in acute back pain in 113 people after two and four days of use, compared to 20 people on placebo. The small study size limits the strength of the results. It may be that paracetamol was not a strong enough painkiller at this point in the course of the back pain, but may have been during the recovery phase.

Third study

The main outcome for the third study was whether paracetamol speeded up the time to recovery from acute lower back pain compared to placebo. How effective paracetamol was at pain relief was a secondary outcome so may not be as reliably assessed.

Some people will find paracetamol helps relieve the pain with relatively few side effects compared to other types of pain killers. The NICE guideline recommends paracetamol as a first line pain relief drug for lower back pain that has lasted for at least six weeks, along with other measures such as staying active. They recommend that if this does not provide adequate pain relief, then an NSAID should be offered.

NICE is currently updating its guidance on lower back pain and will take the results of this review into account.

NICE’s guidance also recommends paracetamol as a first line pain relief drug for osteoarthritis, however it does note that an evidence review suggested paracetamol may not be as effective for these people as originally thought. They are going to be reviewing this guidance (a draft is expected in 2016), and may revise their recommendations at that point, but for now have kept their existing guidance.

If you are finding that any prescribed treatment doesn’t seem to be working then you shouldn’t suddenly stop taking it (unless advised to). You do have the option of contacting your GP or doctor in charge of your care to discuss alternative drug (as well as non-drug) options.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Links To The Headlines

Paracetamol doesn't help lower-back pain or arthritis, study shows. The Guardian, March 31 2015

Paracetamol 'does not help back pain or arthritis'. The Daily Telegraph, March 31 2015

Paracetamol ‘no good for back pain'. BBC News, March 31 2015

Paracetamol for back pain? It's no better than a placebo: Experts say treatment does nothing to improve recovery time, sleep or quality of life. Daily Mail, April 1 2015

Paracetamol is ineffective against lower back pain says study in top medical journal. Daily Mirror, March 31 2015

Paracetamol 'doesn't work on back pain'. ITV News, March 31 2015

Links To Science

Machado GC, Maher CG, Ferreia PH, et al. Efficacy and safety of paracetamol for spinal pain and osteoarthritis: systematic review and meta-analysis of randomised placebo controlled trials (PDF, 672kb). BMJ. Published online March 31 2015

Categories: NHS Choices

Healthy diet could cut risk of Alzheimer's disease

NHS Choices - Behind the Headlines - Tue, 31/03/2015 - 13:44

"A new diet could more than halve a person's risk of developing Alzheimer's disease," the Mail Online reports.

In a new study, researchers looked at the effects of three diets on the risk of developing Alzheimer's disease. These were:

  • a standard Mediterranean-type diet
  • the Dietary Approach to Stop Hypertension diet (DASH) – designed to reduce blood pressure
  • Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) – this combines elements of the Mediterranean diet and the DASH diet

The study found older people whose usual diet was close to any one of these three healthy diets were less likely to develop Alzheimer's disease than those eating less healthily.

The researchers say they found the greatest effect from the MIND diet, which is rich in green leafy vegetables, wholegrains, nuts and berries, even if people didn't follow it closely. Participants who did stick rigorously to the MIND diet were 52% less likely to be diagnosed with Alzheimer's disease.

This large observational study can't show that the diets protected against Alzheimer's, only that there seems to be a link between eating a healthy diet and a lower risk of getting Alzheimer's disease. The three diets weren't compared directly, so we can't be sure which one is best.

The study provides further evidence that eating a healthy diet may reduce the chances of developing Alzheimer's disease

Where did the story come from?

The study was carried out by researchers from Rush University Medical Center in Chicago and Harvard School of Public Health in Boston, and was funded by grants from the US National Institute on Aging.

It was published in the peer-reviewed medical journal Alzheimer's & Dementia.

The Mail Online reported the study accurately for the most part, although it did not say that this type of study cannot prove causation. Strangely, it repeatedly said that the MIND diet called for a daily salad, although salad was not mentioned specifically in the study.  

What kind of research was this?

This was a large prospective cohort study of older people who were taking part in a long-running study of memory and ageing. It aimed to see whether people whose food consumption was closest to one of three types of healthy diet were less likely to be diagnosed with Alzheimer's disease during the course of the study.

As this was an observational study, it cannot prove that the diet protected against Alzheimer's disease or other types of dementia. A randomised controlled trial would be needed for that.  

What did the research involve?

Researchers worked with volunteers living in retirement communities and public housing in Chicago. They were asked to complete a questionnaire to assess their diet. They all had annual neurological examinations for an average of four to five years, which checked for Alzheimer's disease.

Researchers adjusted the results to take account of other factors that can affect Alzheimer's risk. They then looked for links between Alzheimer's diagnosis and people's diets.

At the start of the study, the researchers decided to assess three types of diet:

  • The Dietary Approach to Stop Hypertension (DASH) has been used to reduce blood pressure and stroke risk. It includes total grains and wholegrains, fruit, vegetables, dairy products, meat and fish, nuts and legumes, but restricts fat, sweets and salt.
  • The Mediterranean diet (MEDdiet) is often recommended for heart health. It includes olive oil, wholegrains, vegetables, potatoes, fruit, fish, nuts and legumes, and moderate wine, but restricts full-fat dairy products and red meat.
  • The Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet is a new diet developed by the researchers with elements from the DASH and MEDdiet, and also includes foods thought to protect the brain. It includes olive oil, wholegrains, green leafy vegetables, other vegetables, berries, fish, poultry, beans and nuts, and a daily glass of wine, but restricts red meat and meat products, fast or fried food, cheese, butter, pastries and sweets.

Using questionnaires from 923 volunteers, the researchers assessed how well each of them scored on each diet. They divided people into three groups showing high, moderate or low scores for each diet.

They then looked at whether people in the high-scoring groups for each diet were less likely to be diagnosed with Alzheimer's disease during the average 4.5 years of follow-up, compared with people in the low-scoring groups.

People diagnosed with other types of dementia, such as dementia with Lewy bodies or vascular dementia, were not included as Alzheimer's cases.

The researchers did a good job of checking for other factors that could affect Alzheimer's risk. This included testing for a type of gene (APOE) that raises the risk of Alzheimer's, as well as asking about people's education level, whether they took part in cognitively stimulating activities such as playing games and reading, how much physical activity they got, their body mass index (BMI), whether they had symptoms of depression, and their medical history.  

What were the basic results?

During the study, there were 144 cases of Alzheimer's disease among the 923 people taking part.

People with the highest scores in all three diets were less likely to be diagnosed with Alzheimer's disease than people with the lowest scores.

The link was slightly stronger for the MIND and MEDdiet than the DASH diet. People who had the highest scores on the MIND diet were 52% less likely to be diagnosed with Alzheimer's disease (hazard ratio [HR] 0.48, 95% confidence interval [CI] 0.29 to 0.79).

People who had moderate scores for the MIND diet were also less likely to be diagnosed with Alzheimer's than those with the lowest scores, but the link was not as strong (HR 0.64, 95% CI 0.42 to 0.97). Moderate scores on the DASH and MEDdiet did not show a statistically significant reduction in risk.  

How did the researchers interpret the results?

The researchers said their results showed that "even modest adherence" to the MIND diet "may have substantial benefits" for preventing Alzheimer's disease.

They say that while the DASH and MEDdiet also showed positive results, "only the highest concordance" with those diets was linked to the prevention of Alzheimer's disease.

They go on to speculate that the dairy and low-salt recommendations in DASH, while useful for reducing blood pressure, may not be particularly relevant to brain health.

They concluded that, "High-quality diets such as the Mediterranean and DASH diets can be modified ... to provide better protection against dementia." 

Conclusion

The study found people who ate a healthy diet – with plenty of green vegetables, wholegrains, legumes and less red meat – may be less likely to get Alzheimer's disease. However, we should be wary of saying that their diet actually protected them from Alzheimer's, as it is a complex disease with many potential causes.

The main limitation is that observational studies cannot prove causation, even when researchers take care, as they did here, to include factors that we know affect disease risk. It's also notable that the researchers excluded dementia, other than Alzheimer's disease, from their calculations.

It would be interesting to see the effect of these diets on other types of dementia, too, especially as the DASH diet protects against hypertension, which can be a cause of vascular dementia. This was not taken into consideration when the authors concluded that low dairy and salt may not be needed for brain health (though they still remain part of a healthy, balanced diet).

Another limitation is that the food frequency questionnaire may not have completely captured people's adherence to the three diets. For example, people were asked about how often they ate strawberries, not about other types of berries. This could underestimate the effect of berry consumption in the diet.

Experts already think a healthy lifestyle can help lower the risk of getting dementia. Recommendations include eating a healthy diet, keeping to a healthy weight, exercising regularly, not smoking, drinking in moderation, and keeping blood pressure healthy. The question is: what type of healthy diet is best?

This study suggests the MIND diet may be better at lowering the risk of Alzheimer's disease than two other healthy diets. However, the study did not compare the effect of the diets directly.

We also don't know which foods in the diets might make the difference. The best advice may be to follow a healthy balanced diet, without worrying too much about exactly which foods might protect your brain.

Analysis by Bazian. Edited by NHS ChoicesFollow Behind the Headlines on TwitterJoin the Healthy Evidence forum.

Links To The Headlines

The 10 foods that HALVE the risk of Alzheimer's and the 5 that harm the brain: Stock up on berries, salad and wine - but avoid cheese, pastries and sweets. Mail Online, March 30 2015

Links To Science

Morris MC, Tangney CC, Wang Y, et al. MIND diet associated with reduced incidence of Alzheimer's disease. Alzheimer's & Dementia. Published online February 11 2015

Categories: NHS Choices

Sperm quality pesticides claim 'should be treated with caution'

NHS Choices - Behind the Headlines - Tue, 31/03/2015 - 11:31

"Pesticides on fruit and vegetables may be damaging sperm counts and men should consider going organic if they want to have children," The Daily Telegraph reports.

A study found men who ate the highest amount of fruit and vegetables with high levels of pesticides had a 49% lower sperm count, as well as a 32% lower count of normally formed sperm, than men who consumed the least amount. Sperm can sometimes be an abnormal shape, making it harder for them to move and fertilise an egg.

The results of this study should be viewed with caution. Researchers did not assess individual diets for pesticide residues. They also did not know if the food the men ate was grown organically or conventionally (a failing The Telegraph overlooked). 

So it is possible the men's dietary exposure to pesticides was misclassified. The men in the study were all attending fertility clinics, so the results may not apply to the general population.

The study certainly should not be seen as an invitation to avoid eating fruit and vegetables. Aside from the general health harms a fruit and veg-free diet would hold, this could also negatively impact your sperm quality.

Many factors can affect men's sperm count and quality, including whether they smoke or drink alcohol, as well as how much exercise they take and their weight. Whether or not pesticide residue found in our diet is another factor that affects sperm quality is an important topic that needs further study. 

Where did the story come from?

The study was carried out by researchers from the Harvard T H Chan School of Public Health, Massachusetts General Hospital, Brigham and Women's Hospital, and Harvard Medical School in the US.

It was funded by the National Institute for Environmental Health Sciences, the National Institutes of Health, and the Ruth L Kirschstein National Research Service Award.

The study was published in the peer-reviewed journal Human Reproduction on an open-access basis, so it is free to read online.

The study was covered uncritically by most of the UK media. The Telegraph's assertion that, "Men who eat fruit and vegetables with high pesticide residues could double their sperm count by switching to organic food" was highly misleading.

The study did not compare the effects of organic and non-organic food on sperm count. However, both The Telegraph and the Mail Online included comments from UK experts. 

What kind of research was this?

This was a cohort study exploring whether the consumption of fruits and vegetables with high levels of pesticide residues is linked to lower semen quality.

This type of study cannot prove cause and effect, as other factors could be causing any effects seen. However, in studies of this type, researchers try to take account of other factors that can affect a health outcome.

In this case, for example, male fertility is known to be affected by lifestyle factors such as smoking and weight, which were taken into account in the statistical analyses.

The researchers say in nearly one-third of couples seeking help with conception the problem is one of male infertility.

They say occupational exposure to pesticides has been linked to lower sperm counts, and argue that pesticide exposure may explain a general decline in semen quality. Whether pesticide exposure through diet could affect male fertility is unknown. 

What did the research involve?

Men attending a fertility clinic filled out food frequency questionnaires from which the researchers estimated their intake of pesticides from fruit and vegetables. The results were then analysed to look for an association between higher pesticide consumption and lower sperm counts.

Researchers used an ongoing study of couples attending a US fertility clinic. The men in the study had to be aged between 18 and 55 without any history of vasectomy, and be in a couple seeking fertility treatment with their own eggs and sperm.

Between 2007 and 2012, the male partners in sub-fertile couples (couples who require medical assistance to conceive) completed a food frequency questionnaire. They were asked how often on average they consumed specified amounts of fruit and vegetables over the previous year using standard portion sizes.

The fruit and vegetables were categorised as being high, moderate or low in pesticide residues based on data from the annual United States Department of Agriculture Pesticide Data Program.

Fruit or vegetables low in pesticide residues included peas, beans, grapefruit and onions. Those with high residues included peppers, spinach, strawberries, apples and pears. This data takes account of how food has been prepared, such as whether it has to be peeled.

By this criteria, 14 of the fruits and vegetables in the questionnaire were categorised as high in pesticide residues and 21 as low-to-moderate in pesticide residues.

The researchers divided the men into four groups, ranging from those who ate the greatest amount of fruit and vegetables high in pesticide residues (1.5 servings or more per day), to those who ate the least amount (less than half a serving per day).

They also categorised whether men ate a "prudent" diet – consisting of high intakes of fish, chicken, fruit, vegetables and wholegrains – or a "Western pattern" – high intakes of red and processed meat, butter, high-fat dairy, refined grains, snacks, high-energy drinks, mayonnaise and sweets.

Semen samples were also collected from the men over an 18-month period following their dietary assessment. Both sperm count and the size and shape of the sperm and whether they moved normally were evaluated by computer-aided semen analysis (CASA).

A total of 338 semen samples collected from 155 men between 2007 and 2012 were used in the analysis. Fifty-seven men contributed one sample, 51 men provided two samples, and 47 provided three or more semen samples.

Using statistical methods, the researchers analysed the association between pesticide intake from fruit and vegetables with sperm count and quality.

They adjusted their findings for other factors known to affect male fertility, such as age, smoking status, weight, periods of sexual abstinence, exercise, dietary patterns, and history of varicose veins (variocele) in the testicles.

What were the basic results?

The researchers found that:

  • the men's total fruit and vegetable intake was unrelated to their semen quality
  • high pesticide residue fruit and vegetable intake was associated with poorer semen quality
  • on average, men in the highest quartile of high pesticide residue fruit and vegetable intake, with 1.5 or more servings a day, had a 49% (95% confidence interval [CI] 31 to 63) lower total sperm count and a 32% (95% CI 7 to 58) lower percentage of normally shaped sperm than men in the lowest quartile of intake (0.5 servings a day)
How did the researchers interpret the results?

The researchers say their findings suggest that exposure to pesticides used in agriculture through diet may be sufficient to affect the quality and amount of sperm in humans.

Conclusion

Whether pesticide exposure in the diet is linked to male fertility problems is an important issue, but, as the authors point out, there are several reasons to view the results of this trial with caution:

  • the men were all attending a fertility clinic with their partner, so some of them will have had fertility issues unrelated to their diet or lifestyle
  • they used national surveillance data, rather than looking at individual diets, to assess how much pesticide residue the men had consumed
  • they did not have information on whether the men were eating organic or non-organic food
  • the men had to remember and report on their diet over the previous year, which could affect the reliability
  • their diets were only assessed once, which might have led to misclassification, and diets could change over time

Male fertility can be affected by several factors. Although the researchers tried to adjust their findings for these, it is always possible that both measured and unmeasured confounders affected the results. Further studies looking at this important topic are needed.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Links To The Headlines

Pesticide residues on some fruit and vegetables harming men's fertility, study claims. The Independent, March 31 2015

Pesticide in fruit and veg could harm man's fertility: Men who eat high levels have half the sperm count of those who ate the least. Mail Online, March 31 2015

Could switching to organic fruit and veg double sperm count? The Daily Telegraph, March 31 2015

Links To Science

Chiu YH, Afeiche MC, Gaskins AJ, et al. Fruit and vegetable intake and their pesticide residues in relation to semen quality among men from a fertility clinic. Human Reproduction. Published online March 30 2015

Categories: NHS Choices

Meningitis B jab to be added to NHS child vaccine schedule

NHS Choices - Behind the Headlines - Mon, 30/03/2015 - 12:45

"All babies in the UK will soon have a potentially life-saving vaccine against meningitis B," The Guardian reports. The vaccine, Bexsero, will soon be offered to babies once they reach the age of two months, followed by two more booster shots.

 

What is meningitis B?

Meningitis B is a highly aggressive strain of bacterial meningitis that infects the protective membranes surrounding the brain and spinal cord. It is very serious and should be treated as a medical emergency. If the infection is left untreated, it can cause severe brain damage and infect the blood (septicaemia). In some cases, bacterial meningitis can be fatal.

 

How common is meningitis B?

The charity Meningitis UK estimates that there are 1,870 cases of meningitis B each year in the UK. Meningitis B is most common in children under five years old, particularly in babies under the age of one.

Initial signs and symptoms of meningitis B in babies include:

  • a high temperature with cold hands and feet
  • they may feel agitated, but not want to be touched
  • they may cry continuously
  • some children are very sleepy and it may be difficult to wake them up
  • they may appear confused and unresponsive
  • they may develop a blotchy red rash that does not fade when you roll a glass over it

For more information, read about the signs and symptoms of serious illness in babies.

 

Why is this meningitis B vaccine in the news?

The development of a safe and effective meningitis B vaccine is the culmination of more than 20 years of research and represents a significant breakthrough in disease prevention.

 

What do we know about the vaccine?

The vaccine, Bexsero, is thought to provide 73% protection against meningitis B, which should significantly reduce the number of cases. The vaccine can be administered to infants aged two months or older either by itself, or in combination with other childhood vaccines.

The vaccine has been tested in clinical trials involving more than 8,000 people.

In infants, it was found to have similar levels of safety and tolerability as other routine childhood vaccines. The most commonly reported side effects were:

  • redness and swelling at the site of the injection
  • irritability
  • fever

It is thought that the vaccine will become available on the NHS in the autumn.

 

Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Meningitis B vaccine added to UK child immunisation scheme. The Guardian, March 29 2015

Now babies WILL get £20 meningitis jab. After year-long row over cost, NHS gives it the nod. Mail Online, March 30 2015

Meningitis B vaccine deal agreed. BBC News, March 30 2015

Every baby to be vaccinated against meningitis B in world first protection programme. Daily Express, March 30 2015

Links To Science

 

Categories: NHS Choices

Parents fail to spot that their kids are obese

NHS Choices - Behind the Headlines - Mon, 30/03/2015 - 12:31

"Parents hardly ever spot obesity in their children, resulting in damaging consequences for health," BBC News reports after a new study found a third of UK parents underestimated the weight of their child.

The study asked parents for their views about whether their child was underweight, a healthy weight, overweight or obese, comparing this with objective measurements of the child's weight and height taken on the same day.

Researchers found most parents were only likely to think a child was overweight when they were at the top end of the very overweight category.

The study was large, with almost 3,000 participants, but may not be representative of all parents in the UK, as many of those asked did not participate.

The study also cannot tell us why parents are not recognising when their child is overweight, or the best and most effective way of improving this. But it does suggest that some help is likely to be needed to make sure parents know when their child is overweight.

If you are concerned your child may be overweight, it is better to act quickly. Research suggests obesity in the teenage years tends to persist into adulthood.

Read more advice about obesity in childhood

Where did the story come from?

This study was carried out by researchers from the London School of Hygiene and Tropical Medicine, the University of Bristol, University College London, and Imperial College London, and was funded by the National Institute for Health Research.

It was published in the peer-reviewed British Journal of General Practice. One of the researchers received funding from the National Institute for Health Research.

The UK media generally reported the findings of the study accurately. They also speculated about the causes of the discrepancy. The Telegraph and BBC News, for example, suggested that being overweight is now "the norm", making it hard for parents to tell when their children are not a healthy weight.

"Society as a whole has become so fat we have collectively lost our sense of a healthy weight," said the BBC. But while the authors of the study do discuss possible reasons, the study did not directly assess whether these explain the discrepancy. 

What kind of research was this?

This was a cross-sectional study that compared parents' perceptions of their child's weight with objective measurements taken by school nurses. The researchers looked at how far the parents' assessments agreed with the objective assessments.

National figures show one-third of children in England aged 10 and 11 were overweight or very overweight in 2012-13. Overweight children have a higher chance of getting serious health problems such as type 2 diabetes in later life.

Previous studies showed only about half of parents can identify when their child is overweight. The researchers wanted to know at what point parents thought a child was overweight and what factors might affect this. The study didn't assess why people might wrongly estimate their children's weight. 

What did the research involve?

Every year, children in reception class (aged 4 to 5) and year 6 (aged 10 to 11) at state schools in England have their height and weight measured. This information was used to classify the children's weight against national standards.

Researchers sent questionnaires to the parents of children from five primary care trusts in England who were being measured in 2010-11. They asked the parents to estimate whether their child was underweight, a healthy weight, overweight, or very overweight.

They then compared the results of the children's measurements with what the parents thought, and looked for factors that were linked to their likelihood of estimating the child's weight correctly.

The children's weight and height was converted into body mass index (BMI) and then compared with reference measurements taken from British children from 1978 to 1990.

These measurements are organised in order of increasing BMI and split into 100 groups, or centiles, of increasing BMI, each containing 1% of the reference measurements. This shows the distribution of BMI for children at different ages and is the standard way of categorising child weight.

Children are categorised as underweight if their BMI is at or below the 2nd centile, a healthy weight if they are between the 2nd centile and the 85th centile, overweight at or above the 85th centile, and very overweight (obese) if they are at or above the 95th centile.

Researchers took the objective category for each child and compared it with the parents' assessment. They then looked at what point parents would be likely to categorise a child as underweight or overweight.

They also looked at the children's age, sex, ethnic group, school year and the local area's levels of deprivation to see if they could identify factors associated with parents being more or less likely to underestimate or overestimate their child's weight status.

Because so few parents categorised their children as being very overweight (obese), the researchers combined the very overweight and overweight groups for some of their calculations. 

What were the basic results?

Using the four categories of underweight, healthy weight, overweight, or very overweight, 68% of parents correctly categorised their child. Few parents (less than 1%) overestimated their child's weight status, but 31% underestimated it, believing them to be a healthy weight or even underweight when they were actually overweight or very overweight.

Only four parents described their child as being very overweight, although the objective measurements placed 369 children in that category. Parents only became more likely to categorise a child as overweight rather than a healthy weight once the child was at the extreme end of the spectrum: at or above the 99.7th centile of BMI for their age.

As an example, a child at the 98th centile, which is classed as very overweight according to national standards, had an 80% chance of being seen as a healthy weight by their parents, and only a 20% chance of being seen as overweight or very overweight.

There were similar findings for the underweight category, with parents only becoming more likely to categorise a child this way if they were at the extreme end of the spectrum (under the 0.8th centile), compared with under the 2nd centile national threshold.

The researchers said parents were more likely to underestimate their child's weight status if the children were black, south Asian, male, or older (in year 6 rather than reception). Families from better-off areas were less likely to underestimate their child's weight status.  

How did the researchers interpret the results?

The researchers concluded there is "extreme divergence" between the parents' estimation of their child's weight status and their categorisation according to their BMI.

They say parents who are "unable to accurately classify their own child's weight" may be less likely to be "willing or motivated" to make changes at home that could help the child to reach and maintain a healthy weight.

The researchers suggest some reasons for the discrepancy between parents' estimates and the medical assessments, including fear of being judged and unwillingness to label a child as overweight, as well as "shifting perceptions of normal weight" because society as a whole has seen an increase in body weight.

They say there's a need for measures to bridge the gap between parents' perceptions of a child's weight status and the BMI categories used by medical professionals.

Conclusion

This study found parents in the UK are much less likely to think their child is overweight or very overweight than standard childhood BMI categories suggest. It also found parents of black or south Asian children, boys, and those from more deprived areas are more likely to underestimate their child's weight status.

But this research has some limitations. While it is based on a fairly big sample size (2,976 children who had completed parental questionnaires stating their estimated weight classification and objective weight measurements), only 15% of the parents contacted actually sent back the questionnaire, and not all of them answered the question about weight status.

This means we cannot be sure that these children are representative of all the children in the areas selected for the study (Redbridge, Islington, West Essex, Bath, and North East Somerset and Sandwell). Therefore, these findings may not be representative of all parents in those areas or other areas in the UK.

There is also some debate about the most appropriate ways to measure being overweight or obese. Research from 2014 suggests using the BMI method (where weight is compared to height) is less accurate with children than with adults. 

Although researchers looked for factors affecting the parents' estimates, including ethnicity and measures of deprivation of the local area, they did not look at other factors that might also be related to parental perception – for example, the parents' own weight status, anything about the family diet, or the amount of exercise the children got. This limits the conclusions that can be drawn from the study.

While the authors discussed some possible reasons for the discrepancy between parents' estimates and the objective assessments, the study did not assess this directly, so we can't be sure what those reasons are. The study can't tell us why, for example, parents of boys or south Asian children are less likely to recognise that their child is overweight.

And we don't know if the problem is restricted to parents, or whether other professionals, such as teachers and nurses, would also underestimate a child's weight status. It's even possible that parents might not recognise that their own child is overweight, but would be able to spot it in other people's children.

It is a concern that parents don't recognise their children's weight problems – we know these children are at a higher risk of getting health problems in later life.

The authors note that a 2011 Cochrane review suggested parental support could be one important part of bringing about lifestyle changes at home and reducing childhood obesity.

Helping parents gain a better understanding of what a healthy weight looks like in a child could help reduce this problem and help improve children's long-term health.

If you're concerned your child may be too heavy, ask your GP to check whether they weigh more than they should for their age. The good news is that teaching them about healthy eating and regular exercise can lead to weight loss, as well as instilling healthy habits that may persist into adulthood. 

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Links To The Headlines

Parents rarely spot child obesity. BBC News, March 30 2015

Obesity: parents unable to recognise if child is overweight. The Guardian, March 30 2015

Just one in 100 parents spot obesity in their children. The Daily Telegraph, March 30 2015

Parents fail to see that their own children are fat. The Times, March 30 2015

Parents 'do not recognise their own child's obesity'. ITV News, March 30 2015

Links To Science

Black JA, Park M, Gregson J, et al. Child obesity cut-offs as derived from parental perceptions: cross-sectional questionnaire. British Journal of General Practice. Published online March 30 2015

Categories: NHS Choices

Fit middle-aged men have lower cancer risk

NHS Choices - Behind the Headlines - Fri, 27/03/2015 - 13:00

"Very fit men in their late 40s are less likely to get lung cancer and colorectal cancer than unfit men," says BBC News as it reports on a new US study.

The study involved a comprehensive fitness test of 13,949 US men. They were split into three fitness groups: lowest 20%, middle 40% and top 40%, and followed for an average of 6.5 years to see if fitness affected their chance of developing certain cancers.

Men in the fittest group were 55% less likely to develop lung cancer and 46% less likely to develop colorectal cancer compared with men in the lowest fitness group.

Perhaps surprisingly, men in the top group actually had a 22% higher risk of prostate cancer.

One obvious point is that men who exercise to stay fit are usually healthy in other ways too, such as eating a healthy diet and abstaining from alcohol. This could have influenced the results.

Still, there is evidence that exercise alone can reduce your cancer risk. Information provided by Cancer Research UK explains how exercise can reduce inflammation and prevent bowel damage, which may reduce cancer risk.

With its proven effect of preventing heart disease, regular exercise is always a good idea, whatever your age or sex. Read more about the benefits of exercise

Where did the story come from?

The study was carried out by researchers from the University of Vermont, the University of Texas Southwestern Medical Center, Duke University Medical Center in Dallas, and the Memorial Sloan Kettering Cancer Center in New York.

It was funded by the US National Institute of General Medical Sciences, the National Institutes of Health, and the National Cancer Institute.

The study was published in the peer-reviewed science journal JAMA Oncology. It was published as an open-access article, meaning it is free to read and download online.

Generally, the UK media reported the story accurately, but none mentioned the possibility that diet could be accounting for some of the improvements seen, not just fitness.

What kind of research was this?

This was a longitudinal study looking at whether cardiorespiratory fitness (having both a healthy heart and lungs) prevents or improves outcomes in cancer.

It used data already collected as part of the long-running Cooper Center Longitudinal study.

There are many risk factors for cancer, including age, diet and physical activity. This study focused on fitness and whether this helped men develop fewer cancers, and survive better if they did develop cancer.  

What did the research involve?

The research analysed fitness data on 13,949 US men collected as part of the Cooper Center Longitudinal study between 1971 and 2009.

The men were split into three fitness groups: lowest 20%, middle 40% and top 40%, and followed for an average of 6.5 years to see if fitness levels affected their chance of developing lung, colorectal or prostate cancer.

Fitness was assessed using an incremental treadmill test, which tests a person's ability to run to exhaustion.

The outcomes researchers were most interested in studying were:

  • new cases of prostate, lung and colorectal cancer 
  • death from any cause for men developing cancer over the age of 65
  • cause-specific death, such as cardiovascular disease, for men developing cancer over the age of 65

Cancer diagnosis and notification of death came from Medicare claims data, which is the US government health insurance system covering people over 65.

The statistical analysis took account of many common cancer risk factors, but not diet or the stage of cancer at diagnosis.

The confounding factors adjusted for included:

  • age
  • examination year
  • body mass index (BMI)
  • smoking
  • total cholesterol level
  • systolic blood pressure
  • diabetes mellitus
  • fasting glucose level  
What were the basic results?

Over the study period, 181 men were diagnosed with colon cancers, 200 with lung cancers, and 1,310 with prostate cancers.

The main message from the results is that exercise is very good at reducing the risk of developing lung and colorectal cancer, as well as helping reduce the risk of dying from cancer or cardiovascular disease. The pattern of risk for prostate cancer was less clear. 

Men in the fittest group were 55% less likely to develop lung cancer (hazard ratio [HR] 0.45; 95% confidence interval [CI], 0.29 to 0.68), and 46% less likely to develop colorectal cancer (HR, 0.56; 95%; CI, 0.36 to 0.87), compared with men in the lowest fitness group. The risk of prostate cancer was actually 22% higher (HR 1.22; 95%; CI, 1.02 to 1.46).

Similar benefits were seen comparing the middle exercise group with the lowest exercise group, but the risk differences were slightly smaller.

For example, risks were 43% lower for lung cancer and 33% lower for colon cancer compared with the lowest fitness group. This time there was no difference for prostate cancer. This analysis covered cancers diagnosed at any age.

Looking only at cancers diagnosed after the age of 65, the fittest group were 32% less likely to die from cancer compared with men in the lowest fitness group (HR, 0.68; 95%; CI, 0.47 to 0.98) – this included prostate cancer.

They were also 68% less likely to die from cardiovascular disease after a cancer diagnosis (HR, 0.32; 95%; CI, 0.16 to 0.64) compared with the least fit men. 

How did the researchers interpret the results?

The authors concluded that, "There is an inverse association between midlife CRF [cardiorespiratory fitness] and incident lung and colorectal cancer, but not prostate cancer. High midlife CRF is associated with lower risk of cause-specific mortality in those diagnosed as having cancer at Medicare age [over 65]." 

Conclusion

This study shows that cardiovascular fitness is likely to reduce men's chances of developing lung and colorectal cancer, and appears to boost survival from cancer or cardiovascular disease in those diagnosed after the age of 65. This was based on comparing the top 40% of fittest men with the 20% least fit.

The study focused on fitness and took account of major risk factors for cancer, such as smoking and blood pressure. However, it left out one important risk factor: diet. What people eat and drink is known to affect cancer risk.

The fittest group may also have been the healthiest in terms of eating well and drinking alcohol within safe limits. This probably accounted for some of the risk reductions seen in this study. What proportion? We don't know. 

This, in effect, makes this a study of healthiness incorporating fitness and diet. The evidence that eating well and being active reduces the risk of cancer, heart disease, stroke and diabetes is already well established. Studies have also shown regular physical activity also benefits our mental health.

Read more about reducing your cancer risk.

Although fitter men over the age of 65 diagnosed with cancer had better survival rates, there are other unmeasured factors that could have contributed. It is not known whether the fitter people were diagnosed with cancer at an earlier stage, which would have increased their chance of survival.

There was also a counterintuitive finding worth noting. The fittest group were more likely to be diagnosed with prostate cancer than the least fit. This is important, as prostate cancer risk was much higher than lung or colon cancer in the sample.

The study authors thought this might be because fitter men go for more cancer tests in the US than unfit men, so therefore the cancer is discovered and diagnosed more often in that group.

It could also be the case that men in the fittest group would probably live longer, and prostate cancer is an age-related disease.

But we don't know this for sure, and there could be other explanations worth investigating.

Would you know if you had prostate cancer? Read more about prostate cancer symptoms.

Analysis by Bazian. Edited by NHS ChoicesFollow Behind the Headlines on TwitterJoin the Healthy Evidence forum.

Links To The Headlines

Fit middle-aged men 'at lower risk for some cancers'. BBC News, March 27 2015

Keep fit to beat cancer: Looking after yourself in middle age boosts men's chances. Daily Mirror, March 27 2015

Keeping fit helps men with cancer to boost survival chances by a third. The Times, March 27 2015

Links To Science

Lakoski SG, Willis BL, Barlow CE, et al. Midlife Cardiorespiratory Fitness, Incident Cancer, and Survival After Cancer in Men - The Cooper Center Longitudinal Study. JAMA Oncology. Published March 26 2015

Categories: NHS Choices

Crossing your fingers may help reduce pain

NHS Choices - Behind the Headlines - Fri, 27/03/2015 - 11:00

"Crossing your fingers might reduce pain," says The Guardian. The study behind the news found crossing your fingers may confuse the way your brain processes feelings of hot and cold – and, in some cases, reduce painful sensations.

Rather than subjecting the participants to "normal" pain, the authors used a trick known as the thermal grill illusion. The thermal grill illusion is not the latest in BBQ technology, but an unusual – and well validated – phantom pain effect.

When the skin is subjected to an alternating pattern of harmless coldness followed by heat, it creates a sensation of "burning coldness", but does no damage to the skin. It is something akin to the burning sensation felt by anyone placing cold hands under warm water after a snowball fight.

The researchers applied hot and cold sensations to the ring, middle and index fingers to create phantom pain sensations in volunteers. The phantom pain reduced in some people when they crossed their fingers.

This artificial phantom set-up means the findings probably don't apply to most real-life experiences of pain. Would a woman crossing her fingers during childbirth feel some benefit, or would someone who has just hit their thumb with a hammer? Probably not.

We shouldn't get too hung up on the crossed finger idea, though. The concept behind it is more interesting. The study tentatively showed that pain might be influenced by how our bodies are organised in space and relative inputs from different parts of your body.

If it is found to be a regular and real occurrence through more research, this may have potential for use in pain management in healthcare.

Where did the story come from?

The study was carried out by researchers from University College London (UCL) and the University of Verona (Italy).

It was funded by the CooperInt Program from the University of Verona, the European Union Seventh Framework Programme, the Economic and Social Research Council, and the European Research Council.

The study was published in the peer-reviewed science journal Current Biology.

The Guardian reported the story accurately, making it clear it was not real-world pain, but phantom pain from the thermal grill illusion.

The paper interviewed Elisa Ferrè of UCL and a co-author, who said: "There might be applications for treating people with chronic pain … the position of your limbs or digits is something that would be very easy to manipulate."

Adding a welcome note of caution, The Guardian wrote: "The findings did not establish whether crossing your fingers would be as soothing with a real painful stimulus, rather than an illusory one, but Ferrè said her hunch is that it would help."

What kind of research was this?

This was a study of human volunteers investigating whether pain perception is influenced by the position of their fingers.

Rather than subjecting the participants to conventional pain, the team used a trick known as the thermal grill illusion to create a phantom pain sensation.

Controlled experiments such as these are useful for developing new ideas and testing them in the early stages. But testing pain in an indirect manner like this isn't ideal. It would be more useful to devise a test using actual pain, but this has ethical dimensions to consider.

What did the research involve?

The researchers used three heat pads under the index, middle and ring fingers of participants to test different combinations of the thermal grill illusion, and whether crossing fingers reduced the phantom pain.

Participants also adjusted a temperature delivered to the other hand until it matched their perception of the cold target finger (index or middle).

The thermal grill illusion works by applying a warm sensation to the index and ring fingers, and a cold sensation to the middle finger. The grill-like pattern of warm-cold-warm creates a burning sensation in the middle finger, even though it is in fact exposed to cold.

About half of people go as far as describing the feeling as painful. The sensation is much more intense than the hot or cold on their own.

According to the researchers, the illusion might work because the hot sensation in the outer two fingers blocks the activity in a certain cooling receptor under the skin. With this pathway blocked, the hot signals from the nearby hot areas are felt more intensely.

What were the basic results?

The study found significant temperature overestimation when the target finger was in the middle (warm-cold-warm) compared with on the end (cold-warm-warm).

The effect depended on the target finger being in the middle of thermal inputs, but it didn't matter whether this was the index or middle target fingers.

The thermal grill effect for the middle finger was abolished when it was crossed over the index. The same effect was generated for the index finger when it was crossed with the middle.

How did the researchers interpret the results?

The team concluded that, "Our results suggest that the locations of multiple stimuli are remapped into external space as a group; nociceptively mediated sensations [pain perception] depended not on the body posture, but rather on the external spatial configuration formed by the pattern of thermal stimuli in each posture."

Conclusion

This study investigated pain using a thermal grill trick, which applies hot and cold in different combinations to the index, middle and ring fingers to induce a phantom burning sensation.

This showed that crossing your fingers may confuse the way your brain processes feelings of hot and cold, and in some cases stopped the phantom pain.

The biggest limitation of this study is that it looked at phantom pain using the thermal grill trick, rather than actual pain. Phantom pain may be different from "normal" pain, so the results may not relate to a regular pain situation.

We shouldn't get too hung up on the crossed finger idea, though. The concept behind it is more interesting. The study tentatively showed that pain might be influenced by how our bodies are organised in space, and relative inputs from different parts of your body.

If found to be a regular and real occurrence through more research, this may have potential for use in pain management in healthcare.

For example, The Guardian says: "Scientists believe the phenomenon could ultimately be harnessed to help treat chronic pain patients, who suffer from painful sensations, often long after a physical injury has healed."

At present, this is largely speculative. The study only showed reduction in phantom pain, and only under a very specific and artificial set of circumstances. Research that is more relevant and applicable to real life would be the logical next step for this research field. 

Still, how we think about pain can sometimes alter how it much it affects us. Many people find cognitive behavioural therapy (CBT) techniques can be useful in helping people cope better with chronic pain.

Read more about coping with pain.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Links To The Headlines

Crossing your fingers might reduce pain, says study. The Guardian, March 26 2015

Crossing your fingers actually DOES help – just not the way you expect. Metro, March 26 2015

Links To Science

Marotta A, Ferrè ER, Haggard P. Transforming the Thermal Grill Effect by Crossing the Fingers. Current Biology. Published online March 26 2015

Categories: NHS Choices

Do antibiotics in pregnancy cause cerebral palsy and epilepsy?

NHS Choices - Behind the Headlines - Thu, 26/03/2015 - 12:00

"Antibiotic used in pregnancy linked to risk of epilepsy and cerebral palsy," The Guardian reports.

The results of a new study suggest women who take macrolide antibiotics were slightly more likely to give birth to a child with one (or both) of these conditions, compared with women who take penicillin.

But no association was found between taking antibiotics in general during pregnancy and cerebral palsy (a condition that causes movement disorders) or epilepsy (a condition that causes seizures).

However, a direct comparison between these groups of women is not entirely reliable. There could be other confounding factors that could account for the difference seen, such as the type and severity of infection.

The study does not prove that macrolides cause either cerebral palsy or epilepsy. It is possible an underlying infection in pregnancy increased the risk of these conditions, rather than the treatment itself.

There is no such thing as an entirely 100% risk-free medical intervention. This means we need to use the best evidence available to make an informed decision about the trade-off between the benefits and risks of various choices.

Most experts would agree that the benefits of treating bacterial infections in pregnancy far outweigh the potential risks of antibiotics – if infections are left untreated, it could result in the infection being passed on to the baby, or most seriously, miscarriage or stillbirth

Where did the story come from?

The study was carried out by researchers from University College London and the Farr Institute of Health Informatics Research, London, and was funded by the Medical Research Council.

It was published in the peer-reviewed journal PLOS One on an open-access basis, so it is free to read online.

The Guardian, The Daily Telegraph and the Mail Online's reporting was accurate and responsible. All three papers pointed out that the increased risk from macrolides found in the study was small and could be explained by other factors (confounders).

The papers also included advice from experts that women should continue to take antibiotics prescribed for infection.

It is a shame, then, that all three papers chose to run with alarmist headlines that failed to put the increase in risk into any useful context.

The papers also singled out a common antibiotic called erythromycin. This belongs to the group called macrolides, but it was not focused on by the study.

What kind of research was this?

This was a retrospective cohort study involving 195,909 women. It looked at whether antibiotics prescribed during pregnancy were linked to a higher risk of cerebral palsy or epilepsy in their children.

Cohort studies are often used to look at whether particular events are linked to certain health outcomes. The advantage with this type of study is that it can follow large groups of people over long periods of time, but they cannot prove cause and effect.

Retrospective cohort studies, which look back over time, may also be less reliable than those that follow people in time, called prospective cohort studies.

The authors say antibiotics are one of the most frequently prescribed drugs during pregnancy.

However, they say one large randomised controlled trial (RCT) found certain antibiotics given to women who had gone into premature labour were associated with an increased risk of cerebral palsy or epilepsy in their children at seven years of age.

The two antibiotics used in this previous trial were erythromycin, a macrolide, and co-amoxiclav, which is a type of penicillin.

What did the research involve?

The researchers used data on 195,909 women who had registered at their GP surgeries before pregnancy and had a baby born at or after term (37 weeks).

For women with multiple pregnancies (about one-quarter of the cohort), one pregnancy was selected randomly for analysis. Women whose children were born preterm were excluded because premature babies already have an increased risk of cerebral palsy and epilepsy.

They looked at whether the women had been treated with any oral antibiotics during pregnancy, and, if so, which class of antibiotics, the number of courses they had, and the timing of treatment during pregnancy.

The women's children were followed until seven years of age for any diagnosis of cerebral palsy or epilepsy, as recorded in the children's primary care records.

The researchers analysed the data using standard statistical methods. They adjusted their results for a wide range of maternal risk factors.

These included maternal age at delivery; pregnancy complications; chronic conditions such as obesity; treatment for chronic medical conditions during pregnancy; tobacco and alcohol use; social deprivation; and maternal infections that could potentially cause damage to the foetal brain.

What were the basic results?

A total of 64,623 (33.0%) of the women were prescribed antibiotics in pregnancy, and 1,170 (0.60%) children had records indicating they had cerebral palsy or epilepsy, or both.

Once the researchers adjusted their results for confounders, they found:

  • no association between antibiotics and cerebral palsy or epilepsy (hazard ratio [HR] 1.04, 95% confidence interval [CI] 0.91-1.19)
  • compared with penicillins, macrolide antibiotics were associated with a 78% increased risk of cerebral palsy or epilepsy (HR 1.78, 95% CI 1.18-2.69; number needed to harm 153, 95% CI 71-671)
  • children whose mothers received more than three antibiotic prescriptions during pregnancy had a 40% increased risk (HR 1.40; 95% CI 1.07-1.83) compared with those with no prescriptions
How did the researchers interpret the results?

The researchers say that their findings indicate the prescribing of macrolides in pregnancy is linked to an increased risk of cerebral palsy or epilepsy in childhood.

They speculated about why macrolides might be associated with harm – arguing, for example, that if women stopped taking the drugs because of side effects, the partially treated infection might prolong the foetal brain's exposure to inflammation.

However, they add that there is growing evidence that taking macrolides during pregnancy is associated with harm, and these drugs may have specific adverse effects on the foetus.

Conclusion

The findings from this large study indicate that antibiotic use in pregnancy was not associated with an increased risk of cerebral palsy or epilepsy. The apparent increased risk of macrolides compared with penicillin is not reliable.

A direct comparison between the women taking each type of antibiotic is inaccurate, as it does not take into account potential confounding factors. These include:

  • the type and severity of the infections, which could have affected the baby, rather than the antibiotic
  • whether the women took all of the course of antibiotic or not as a result of side effects; if stopped early, the infection may not have been fully cleared and could have then harmed the baby
  • other unmeasured maternal factors that influenced the type of antibiotic the women were given, such as other medications or health conditions

Additionally, the analysis for macrolides was based on small numbers of women, so the results could also have occurred by chance. It is important to stress that the risk to individual pregnancies is small.

Doctors will only prescribe antibiotics in pregnancy if they think there is a clear clinical need, where mother and baby are potentially at threat. Any risk to your pregnancy posed by antibiotics will probably be far outweighed by the benefits of treatment.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Links To The Headlines

Antibiotic used in pregnancy linked to risk of epilepsy and cerebral palsy. The Guardian, March 25 2015

Antibiotic pills 'can hurt unborn baby': Common drug linked to cerebral palsy and epilepsy. Mail Online, March 26 2015

Common antibiotic may double the risk of epilepsy or cerebral palsy in unborn babies. The Daily Telegraph, March 26 2015

Links To Science

Meeraus WH, Petersen I, Gilbert R. Association between Antibiotic Prescribing in Pregnancy and Cerebral Palsy or Epilepsy in Children Born at Term: A Cohort Study Using The Health Improvement Network. PLOS One. Published online March 25 2015

Categories: NHS Choices

Milk and dairy 'good for the brain' claim unproven

NHS Choices - Behind the Headlines - Thu, 26/03/2015 - 00:00

"Three glasses of milk every day ‘helps prevent Alzheimer's and Parkinson's’," is the misleading headline in The Daily Telegraph. The study it reports on only found that a high-dairy diet was linked to increased levels of an antioxidant called glutathione.

It is also unclear what, if any, protective effects higher levels of glutathione would have against Alzheimer’s or Parkinson’s disease.

The study, funded by the US Dairy Research Institute, looked at brain MRI scans of 60 adults aged between 60 and 85 using a new technique that could measure levels of glutathione.

This antioxidant is said to "neutralise" potentially harmful chemicals in the brain. Lower levels are found in conditions such as Parkinson’s disease and Alzheimer’s disease, but it is not known whether this is part of the cause of the conditions or a consequence of them.

The level of glutathione was determined once, at the same time as participants were asked about their diets. This study therefore cannot tell us that a high-dairy diet caused the increased levels of glutathione. It is also unable to show what happens to glutathione levels over time or whether the higher levels are protective.

So, all in all, this study proves little. Dairy products are important for bone health and are recommended in moderation as part of a healthy diet, but we just don’t know if they are good for the brain.

 

Where did the story come from?

The study was carried out by researchers from the University of Kansas Medical Center. It was funded by the US Dairy Research Institute, with further funding provided by the National Institute for Health and the Hoglund Family Foundation. The funding organisations did not have a role in study design, implementation, analysis, or interpretation of data.

The study was published in the peer-reviewed American Journal of Clinical Nutrition.

The Daily Telegraph’s reporting on the story was poor and its headline was inaccurate. It says that people "who guzzled the white stuff were more likely to have healthy brains", when in fact all of the people in the study were healthy. It is also not known whether increased levels of glutathione prevent neurodegenerative disorders, so we can’t say that people with higher levels definitely have "healthier" brains.

The Mail Online’s coverage was slightly more restrained, opting to say that it "may help protect" rather than "will help protect".

 

What kind of research was this?

This was a cross-sectional study, which measured the level of glutathione in the brain using a new MRI scanning technique. Glutathione is an antioxidant which helps prevent damage to cells. Reduced levels of glutathione have been found in the early stages of Parkinson’s disease, though it is unclear if this might contribute to the development of Parkinson’s or is the result of Parkinson’s.

The researchers wanted to see if drinking milk was associated with higher levels of glutathione in the brain. As it was a cross-sectional study, it only measured the level of glutathione at one time point, and did not follow people up over time to find out what happened to them. This means it was not able to show whether dietary consumption might directly affect glutathione levels in the brain, or indeed whether higher levels were protective against brain diseases such as Parkinson’s disease or Alzheimer’s.

 

What did the research involve?

The researchers recruited 60 healthy older adults, assessed their dairy intake and measured their level of glutathione in the brain using an MRI scan. They then analysed whether increased consumption of milk was associated with higher levels of glutathione.

The participants were adults aged between 60 and 85, who were healthy and did not have a history of:

  • neurologic (brain and nervous system) disorders
  • head injury
  • claustrophobia (which would make them unsuitable for MRI scanning, as getting a scan involves lying in a small metal tube)
  • diabetes
  • unstable medical conditions
  • lactose or gluten intolerance
  • taking glutathione or N-acetylcysteine supplements

The participants completed three 24-hour food frequency questionnaires by telephone with a dietician, and a seven-day diet record was filled in before the MRI scan. From these assessments, the researchers categorised the participants into the following three groups, according to their daily consumption of dairy products:

  • low dairy intake, less than one serving per day
  • moderate dairy intake, one to two servings per day
  • "recommended" dairy intake, three or more servings per day (this was based on US recommendations)

They also had other measurements taken, including body mass index (BMI), waist circumference and body composition of fat and muscle. Finally, they had a brain MRI scan using a new process (known as chemical shift imaging) that had been developed by the researchers to measure the level of glutathione.

The results were then analysed to see if increased dairy consumption was associated with higher levels of glutathione.

 

What were the basic results?

The participants’ characteristics were similar across the three groups in terms of age, BMI, educational level and quality of their diet.

Glutathione levels in the front and sides (parietal region) of the brain were higher in people who consumed more dairy products, milk and calcium.

The study did not assess whether this difference would affect a person’s health in any way, or how levels fluctuate over time.

 

How did the researchers interpret the results?

The researchers concluded that "glutathione concentrations were significantly related to adults’ reported consumption of dairy foods and calcium". They say that further research is required to see if increased levels of glutathione prove to be effective in "strengthening cerebral antioxidant defenses [sic] and, thereby, improving brain health in the aging population".

 

Conclusion

This small study found people with higher dairy, milk and calcium consumption had higher levels of glutathione in the frontal and parietal regions of the brain. Glutathione is an antioxidant that helps to "neutralise" potentially harmful chemicals in the brain.

Research into glutathione and its role in neurodegenerative diseases is in the early stages. It is known that the levels reduce with age and in certain conditions such as Alzheimer’s disease and Parkinson’s disease, but it is not known whether this is part of what leads to the disease or a consequence of the disease. This study does not show whether increasing the level of glutathione would protect against these types of conditions.

This study was cross-sectional, so measured the level of glutathione at one time point in older adults who were healthy. It therefore does not answer the question of whether people with more glutathione in their brains are less likely to develop neurodegenerative disorders.

In addition, previous research has found that in Parkinson’s disease, glutathione levels are only reduced in an area of the brain called the substantia nigra, which is located in the middle of the brain. This study did not look at levels in this part of the brain.

This was a relatively small study, which found a relatively wide range of glutathione levels ranged in different areas of the brain. A much larger study would be required to understand what the normal range is in the population, and how this differs in various disease states. The study is also reliant on self-reporting of dietary intake which can be inaccurate. There is also little information about other factors which could influence the results such as socioeconomic status, ethnicity, family history of Alzheimer’s disease or Parkinson’s disease, other conditions or medication use.

In conclusion, this study has found that increased reported consumption of dairy and milk products was associated with increased levels of the antioxidant glutathione in the brain, but it cannot prove that this was due to the diet or that this will prevent brain disease.

Larger studies into the role of both dairy products and glutathione on neurodegenerative diseases would be useful.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Links To The Headlines

Three glasses of milk every day 'helps prevent Alzheimer's and Parkinson's'. The Daily Telegraph, March 25 2015

Three glasses of milk a day 'to beat dementia': People who drink large amounts of the white stuff have higher levels of antioxidant that helps protects brain cells. Mail Online, March 26 2015

Links To Science

Choi I, Lee P, Denney DR, et al. Dairy intake is associated with brain glutathione concentration in older adults. The American Journal of Clinical Nutrition. Published online December 10 2014

Categories: NHS Choices

Frequent antibiotic use linked to higher type 2 diabetes risk

NHS Choices - Behind the Headlines - Wed, 25/03/2015 - 13:30

"Repeated antibiotic use linked to diabetes," BBC News reports.

New research has studied over 200,000 people from the UK who were diagnosed with diabetes between 1995 and 2013. Researchers counted the number of antibiotic prescriptions they had during an average five-year period before they were diagnosed. They compared the number of prescriptions given to an age- and gender-matched control group of over 800,000 people.

They found that people taking antibiotics were more likely to develop diabetes, and those taking more were at a higher risk. For example, people who took five or more antibiotic courses in the five-year period before diagnosis had around a third higher risk of developing type 2 diabetes than those taking no antibiotics.

We should not assume that the results mean antibiotics definitely cause diabetes. It could be the other way round. 

Diabetes is known to increase the risk of infection, especially skin and urinary infections, so it could be diabetes leading to antibiotic use, and not vice versa.

Researchers attempted to adjust for this by only looking at antibiotic use for more than one year before a diagnosis of diabetes was made. However, this may not have been long enough.

It should also be noted the researchers did not take into account other factors that could have caused the results, such as the use of other medications known to increase the risk of diabetes and infections, such as steroids.

If you do find yourself having recurring infections, you should discuss the issue with your GP. There may be an underlying cause that needs investigating.

 

Where did the story come from?

The study was carried out by researchers from the University of Pennsylvania, and Tel-Aviv Sourasky Medical Center and Tel-Aviv University in Israel. It was funded by the US National Institutes of Health.

The study was published in the peer-reviewed European Journal of Endocrinology.

BBC News explained the study well, saying that since people with type 2 diabetes were at a higher risk of developing infections anyway, it was hard to find out which caused which. It quoted professor Jodi Lindsay from St George's, University of London, who explained: "This is a very large and helpful study linking diabetes with antibiotic consumption in the UK, but at this stage we don't know which is the chicken and which is the egg."

While appropriate use of antibiotics is a pressing issue, the study did not look at whether the prescriptions were appropriate or not, they simply counted how many were made.

Read about how a new blood test could help prevent antibiotic misuse – a news story that we published last week.   

 

What kind of research was this?

This was a case-control study looking at whether antibiotic use raised the risk of developing diabetes.

This type of study matches people with a condition, in this case type 2 diabetes, with a control group without the condition who are the same age and sex. They compare many risk factors, in this case antibiotic use, to see if any might be linked with the disease. This type of study can show links between risk factors and disease, but cannot prove cause and effect. This is mainly because it cannot completely control for confounding factors (confounders).

 

What did the research involve?

Using a UK database of medical records, the researchers picked people diagnosed with diabetes and compared their exposure to antibiotics with people of the same age and sex who did not have a diagnosis of diabetes.

The researchers used medical records from 1995 to 2013 from a UK population-based database called The Health Improvement Network (THIN).

They identified 208,002 people who were diagnosed with diabetes during this time period, excluding people who already had a diagnosis of diabetes and those diagnosed within the first six months of the study.

The control group consisted of 815,576 people who were matched for age and sex with the cases. Importantly, they did not have diabetes at the date the case was diagnosed – called the index date.

Both groups were, on average, 60 years old and there was an even gender split.

Using the medical records, the researchers documented how many outpatient antibiotic prescriptions people had been given more than a year before the index date. They collected information on seven commonly used antibiotics, as well as antiviral and antifungal medications.

They analysed differences in antibiotic use, taking into account the following potential confounders, where available:

  • body mass index (BMI)
  • smoking
  • coronary artery disease
  • hyperlipidaemia (high cholesterol) that needed to be treated with statins
  • glucose level before the date of diabetes diagnosis
  • number of urinary tract, skin and respiratory infections before date of diabetes diagnosis

 

What were the basic results?

People with diabetes had a higher rate of infection before the diagnosis index date compared to the controls. Urinary infections, for example, occurred in 19.3% of cases, compared with 15.1% of controls.

Analysis not accounting for confounders showed antibiotic use was linked with higher diabetes risk for all seven antibiotics documented, and for both diabetes types. However, this is a simple analysis, and potentially misleading. Analysis taking account of the confounders is more reliable. This showed higher risks only in those taking more than one course of penicillin, cephalosporins, macrolides and quinolones, and showed almost no change in risk for participants with type 1 diabetes. The increase in risk in type 2 diabetes was higher the more antibiotics people had taken.

Treatment with two to five courses of the following antibiotics was associated with an increased risk of diabetes compared to no use of antibiotics, after adjusting the results for the confounders listed above:

  • 8% increase in risk for penicillin (odds ratio (OR) 1.08, 95% confidence interval (CI) 1.05 to 1.11)
  • 11% increase in risk for cephalosporins, such as cefalexin (OR 1.11, 95% CI 1.06 to 1.17)
  • 11% increase in risk for macrolides, such as erythromycin (OR 1.11, 95% CI 1.07 to 1.16)
  • 15% increase in risk for quinolones, such as ciprofloxacin (OR 1.15, 95% CI 1.08 to 1.23)

Taking more than five courses of antibiotics raised the risk to 23% for penicillin and 37% for quinolones, compared to taking none.

There was no increase in risk for antivirals or antifungals.

 

How did the researchers interpret the results?

The researchers concluded that there is "a higher adjusted risk for type 2 diabetes among individuals with recurrent exposures to penicillin, cephalosporins, macrolides and quinolones". They also found "no increase in adjusted risk for exposure to antiviral or antifungal medications".

 

Conclusion

This large population-based study found a higher risk of diabetes in people taking between two and five courses of antibiotics over a year before diagnosis. This risk was even higher after more than five courses.

Strengths of the study include its large sample size, direct relevance to the UK, and the accuracy of the data.

Despite the strengths, the study does not prove that antibiotics cause diabetes, as its design cannot prove cause and effect. There are both plausible explanations for how antibiotic use may cause diabetes, and how the development of diabetes may cause more antibiotic use. 

For example, people with diabetes are more prone to contracting bacterial infections. It could be that some of the study’s participants were in a prediabetes or undiagnosed diabetes stage when they started taking antibiotics. The researchers tried to take this into account by not including any antibiotic prescription given in the year before diabetes diagnosis, but it is possible that the diagnosis was delayed by more than a year, or signs appeared more than a year before diagnosis.

The second option is that antibiotics contribute to diabetes by altering a person’s microbiota – our internal stock of "good" bacteria and other micro-organisms present in our digestive system.

Other confounders could have accounted for the increased risk found:

  • Increased use of antibiotics is also common in people who take steroids, such as prednisolone. Steroids are known to increase the risk of diabetes.
  • Obesity increases the risk of diabetes, but BMI was not available for 30% of the study's participants.
  • The number of prescriptions of antibiotics was only recorded from 1995 up until the date of diagnosis of diabetes.
  • As the average age of the participants was 60 at the time of diagnosis, this means, at best, that the study did not capture antibiotic use up to the age of 40.
  • The study only recorded outpatient prescriptions; it did not include antibiotics given during hospital admissions.

A further limitation of the study was that the main analysis included people with either type 1 or type 2 diabetes. This muddies the water, as they have different causes. Type 1 diabetes is autoimmune and typically starts in childhood or adolescence, and no clear risk factors have been identified (although a viral cause has been suggested). However, type 2 diabetes has a number of risk factors, including family history, ethnic background and obesity.

The study does provide more of an incentive to only take antibiotics when strictly required. Known risk factors for diabetes that you can change include reducing your waistline, maintaining a healthy weight, reducing high blood pressure, eating healthily and taking regular physical exercise.

Read more about how to reduce your diabetes risk.

Analysis by Bazian. Edited by NHS ChoicesFollow Behind the Headlines on TwitterJoin the Healthy Evidence forum.

Links To The Headlines

Repeated antibiotic use linked to diabetes. BBC News, March 25 2015

Antibiotics linked to a higher risk of Type 2 diabetes: Repeated use of some types of treatment can increase chance by 23%. Mail Online, March 25 2015

Unnecessary prescriptions of antibiotics such as penicillin ‘raise risk of diabetes’. Daily Express, March 25 2015

 

Links To Science

Boursi B, Mamtani R, Haynes K, Yang Y. The effect of past antibiotic exposure on diabetes risk. European Journal of Endocrinology. Published online March 24 2015

Categories: NHS Choices

Study finds link between air pollution and stroke risk

NHS Choices - Behind the Headlines - Wed, 25/03/2015 - 11:30

"Air pollution is linked to an increased risk of stroke," BBC News reports, prompted by a large global study in The BMJ. Researchers found an association even with brief upsurges in air pollution levels.

Previous research has shown a strong link between air pollution and heart attacks, but until now the research looking at air pollution and stroke has had mixed results.

In this study, the researchers summarised all the relevant research published on the topic worldwide. This showed stroke risk was higher on the day of an increase in air pollution and the days immediately after. They also found the effect of pollution was stronger in lower-income countries such as China.

While this type of study cannot prove air pollution is responsible for some strokes, it shows people are more likely to have strokes in the immediate aftermath of episodes of raised air pollution.

The researchers speculated that the association could be the result of a number of possible factors, such as pollution raising blood pressure or constricting blood vessels.

They concluded that governments around the world need to continue to take efforts to reduce the public health burden caused by air pollution.

Where did the story come from?

The study was carried out by researchers from the University of Edinburgh and was funded by the British Heart Foundation. No conflicts of interest were reported.

It was published in the peer-reviewed BMJ on an open-access basis, so it is free to read online or download as a PDF.

Generally, the study was reported accurately in the media. The Mail Online and BBC News gave more detail about the types of pollution causing the problems, and asked questions about why some regions of the UK breach EU pollution limits.

The study has been published in tandem with a related study looking at the links between air pollution and anxiety, which is also open access.

Some media sources have combined a report on both studies into a single story. We have not analysed this second study, so we cannot comment on whether the coverage is accurate.

What kind of research was this?

This was a systematic review of 103 observational studies that looked at the link between air pollution levels and risk of stroke.

The studies included two types of observational study: case-crossover studies and time series studies. A meta-analysis was performed on 94 of the studies, which pooled the results.

Observational studies cannot show that a risk factor such as pollution directly causes an event such as a stroke, although this type of study can show if there is a likely link between the two. The difficulty is adjusting the figures to take account of anything else that might have affected the chances of having a stroke (confounders).  

What did the research involve?

Researchers trawled the scientific literature for studies that included measures of air pollution, deaths from stroke, or admissions to hospital for stroke. They then pooled the estimates of risk of stroke from the individual studies to come up with an overall risk figure for each type of pollutant studied.

The researchers specified the types of studies they would include at the start of their work, and explained in the paper how they excluded research that did not meet quality requirements or did not give the data in a way that they could use.

They included research published in any language, which increased their chances of including research from low- and middle-income countries.

They assessed 2,748 articles and included 103 in the review. Of these, 94 provided data that they were able to include in their analysis. The papers provided information about 6.2 million stroke hospital admissions or deaths from 28 countries.

The researchers used standard analytical techniques to show the increase in stroke risk for each incremental increase in pollution levels for the gases sulphur dioxide, nitrogen dioxide and ozone (all assessed by additional 10 parts per billion), as well as carbon monoxide (assessed by additional part per million).

They also analysed the increase in stroke risk for each incremental increase in fine particles or coarse particles. In addition, they looked at the time lag between stroke and raised pollution levels, and the nation's income status.  

What were the basic results?

Researchers found a "robust and clear" link between gas and particle air pollution levels and admission to hospital for stroke or death from stroke. The link was weakest for ozone and strongest for sulphur dioxide.

Fine particles were more strongly linked to stroke risk than coarse particles, and the link with higher stroke risk lasted longer for high levels of polluting particles than high levels of polluting gases. The increase in relative risk of stroke for each additional increment of pollutant ranged from around 1% to 2%.

To give one example, average (median) pollution levels measured in high-income countries were around 22.6 parts per billion for nitrogen dioxide (the most commonly measured polluting gas).

The increase in stroke risk for each additional 10 parts per billion for nitrogen dioxide was 1.4% (relative risk [RR] 1.014, 95% confidence interval [CI] 1.009 to 1.019).  

How did the researchers interpret the results?

The researchers say they have demonstrated a "marked and close" association between air pollution exposure and risk of stroke. They point out that the study shows low- and middle-income countries have the highest levels of air pollution, and also a "disproportionate burden" of the numbers of strokes worldwide.

They concluded that their study provides sufficient evidence to think that environmental policies intended to reduce air pollution "might reduce the burden of stroke", considering some potential ways that pollution might affect the risk of stroke.

They say air pollution can affect the linings of the blood vessels and the nervous system. This can lead the blood vessels to constrict, blood pressure to rise and blood clots to form – all of these things might increase the chances of having a stroke.  

Conclusion

This study showed a clear link between rises in gas and particle pollution and the chances of being admitted to hospital or dying because of a stroke. The researchers showed the link was strongest on the day of exposure to raised pollution levels.

But this study has some limitations. While systematic reviews are a good way to summarise all the research that has been published on a topic, they are only as good as the individual studies they include.

About two-thirds of the studies used a time series design, which the researchers say is less effective in taking account of trends such as the season of year, rather than the more reliable case-crossover design.

It's also possible that stroke was not diagnosed correctly in some studies. The air pollution data in some studies came from monitoring sites away from city centres, where most people live. This would be likely to underestimate the effect of pollution, as pollution levels are higher in the city centre.

The increase in the chances of having a stroke for any one individual, as demonstrated in this study, is small. However, people cannot usually choose to avoid exposure to air pollution, and many thousands of people are affected when pollution levels rise. According to the Stroke Association, there are around 152,000 strokes a year in the UK.

While there is little people can do to avoid air pollution on an individual level, the study provides new information that governments need to consider when setting policies likely to affect pollution.

Observational studies cannot prove beyond doubt that factors such as pollution directly cause events such as stroke. But this was a comprehensive and careful analysis where the evidence pointed in one direction.

We already know that pollution is likely to increase the risk of heart attacks, and a similar increase would seem to now exist with strokes.

It seems implausible that air pollution alone would trigger a stroke in a healthy individual. But a particularly heavy upsurge in pollution could be the tipping point in people with pre-existing risk factors for stroke, such as obesity and atherosclerosis (hardening of the arteries).

While much has been done to reduce levels of air pollution, it would appear there is much more we could be doing.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Links To The Headlines

Air pollution 'link to stroke risk'. BBC News, March 25 2015

Air pollution 'linked to stroke risk'. ITV News, March 25 2015

Air pollution linked to raised stroke risk: Studies reveal smog connected to death, anxiety and hospital admissions. Mail Online, March 25 2015

Hundreds of thousands of people in stroke risk because of air pollution. Daily Mirror, March 24 2015

Air pollution can cause strokes and raise anxiety, researchers say. Daily Express, March 25 2015

Links To Science

Shah ASV, Lee KK, McAllister DA, et al. Short term exposure to air pollution and stroke: systematic review and meta-analysis. BMJ. Published online March 24 2015

Categories: NHS Choices

Are power naps a 'five-fold' memory booster?

NHS Choices - Behind the Headlines - Tue, 24/03/2015 - 15:00

"A 45-minute power nap can boost your memory five-fold," reports The Independent.

This headline is based on a study that looked at the impact of napping on healthy volunteers’ ability to remember single words or word pairs in a memory test.

After being shown the words for the first time and then being tested on them, volunteers were split into two groups. The first group was allowed a 90-minute nap and the second group were made to stay awake.

It found that those who had a nap remembered similar numbers of word pairs after their nap as they had before their nap, while those who stayed awake tended to not remember as many.

The students tended to forget some of the single words between the two tests, regardless of whether they had a nap.

There are a number of limitations to this study – particularly its small size, with just 41 participants being analysed. This may be why the researchers were not quite able to rule out the idea that the differences between the groups occurred by chance. The limitations mean that we can’t conclusively say that napping is better for memory than not napping based on this study, particularly in real-world situations.

Sleep is known to be important for memory, and there is increasing interest in the effects of napping. For example, a study we discussed earlier this year suggested that napping improves memory retention in infants.

Where did the story come from?

The study was carried out by researchers from Saarland University in Germany. Funding was provided by the German Research Foundation.

The study was published in the peer-reviewed journal Neurobiology of Learning and Memory.

The UK media tended to overplay the findings of this small study. Most of them refer to a "five-fold" improvement in memory, which appears to come from a quote from one of the study authors. The author is also quoted as saying that: "A short nap at the office or in school is enough to significantly improve learning success."

This five-fold figure does not appear to be specifically mentioned in the research paper, and the differences between the groups at the end of the study were not quite large enough to rule out the idea that they occurred by chance.

Although the headlines talk about memory "improvement", what actually happened was that performance on the memory test stayed about the same after a nap, but got worse without one. We also can’t be sure whether the simple tests used in this study are representative of routine office or school tasks.

 

What kind of research was this?

This was a randomised controlled trial (RCT) looking at the effect of a nap on specific aspects of memory.

Sleep is thought to be important for "consolidating" our memories – essentially strengthening them and making it more likely that we remember. The researchers reported that a number of studies have shown that people perform better in certain memory tasks after sleeping than after staying awake for a similar period. However, they say that the effect of naps on different aspects of memory has been studied to a lesser degree.

The researchers wanted to look at the impact of naps on "associative memory" – the ability to learn and remember the relationship between two items – such as a person’s name, which relies on a part of the brain called the hippocampus. They also assessed "item memory" – the ability to remember whether we have seen or heard things before – which does not rely on the hippocampus.

An RCT is the best way to compare the effects of different treatments or interventions – in this case, a nap and a control (watching a DVD). This is because the groups being compared should be well balanced in terms of their characteristics, meaning only the intervention should differ between them and therefore be responsible for the differences in outcome. However, in small studies such as this, even randomly assigning people may not be able to achieve balanced groups.

 

What did the research involve?

The researchers enrolled healthy young university students and tested their memory for word pairs or single words they had been shown. They then randomly allocated them to either have up to a 90-minute nap and then watch a 30-minute DVD, or just watch DVDs for two hours. After this, they tested their memories for the words again, and compared the performance of those who napped and those who stayed awake.

There were 73 students who agreed to take part in the study, but 17 were excluded because the results of their initial memory test suggested that they were just guessing. An additional 15 were excluded after the test, as they performed particularly badly or they had not napped when they were meant to, or napped when they were not meant to. None of the students had sleep disorders or neurological problems, and they were all paid to take part in the study.

The memory test involved showing the students 120 unrelated word pairs (for the associative memory test) and 90 single words (for the item memory test), each appearing briefly on a screen, and asking them to remember them. About half an hour later, the students were shown 60 single words and 60 word pairs, and asked if these were words or pairs they had seen before.

The students then had their nap or watched the DVDs, depending on which group they had been assigned to. The DVDs only had music and images, and not words. Those who had a nap had their brainwaves monitored. They also watched about 30 minutes of one of the DVDs after they woke up to give them a bit of time to get over any residual sleepiness. The groups then did the word test again, this time with 120 word pairs and 120 single words.

The researchers compared the performance of those who napped and those who didn’t, both before and after the nap. They also looked at whether brainwave activity during the nap predicted a person’s performance on the memory test.

 

What were the basic results?

The napping group slept for about 64 minutes, on average.

The researchers found that both those who napped and those who didn’t performed worse on their second single word (item) memory test than they had at the start of the study shortly after they first saw the words.

The group who did not nap also performed worse in their second word pair (associative) memory task than they had at the start of the study. However, those who had a nap performed similarly on the word pair memory task at the start of the study and after their nap. This suggested that the nap had helped them to retain their memories of the words. The difference between the groups in their performance on the second word pair test was near to, but not quite reaching, what would be considered statistically significant (that is, enough to have a high level of certainty that it did not occur by chance).

 

How did the researchers interpret the results?

The researchers concluded that "these results speak for a selective beneficial impact of naps on hippocampus-dependent memories".

 

Conclusion

This small study has suggested that in healthy adults, a nap of about an hour might help to retain one type of newly formed memory – associative memory of unrelated pairs of words – but not item memory of single words.

While the study’s random allocation of participants is a strength, there are limitations:

  • The study was small and only included healthy young adults. The results may not apply to other groups of people, and ideally would be confirmed in larger studies.
  • While the reduction in associative memory in the group that stayed awake was statistically significant, the difference between the napping and non-napping groups in the word pair test at the end of the study was almost, but not quite, large enough to reach this level. That is, it was not quite enough to give a high level of certainty that it did not occur by chance. This may be due to the relatively small size of the study, and again suggests that larger studies are needed.
  • Some students were excluded after they had been randomly allocated to their groups; this can lead to imbalance between the groups and affect results. Ideally, results would have been shown both with and without those students included, to see if it made a difference. Analysing all the participants in the groups to which they were assigned, regardless of what happens to them, is an approach known as "intention to treat".
  • We don’t know how long the effect of the nap would last, as participants were only assessed a short time after their nap – with the tests all happening on one day.
  • The tests were simple word-based memory tests, and naps only affected one aspect of memory. We don’t know whether the naps might make a difference in remembering more complex information or different types of memory not tested in this study.

Overall, the study by itself does not conclusively show the benefits of naps on memory in our day-to-day lives.

Analysis by Bazian. Edited by NHS ChoicesFollow Behind the Headlines on TwitterJoin the Healthy Evidence forum.

Links To The Headlines

A 45-minute power nap can boost your memory five-fold, study finds. The Independent, March 23 2015

A power nap of just 45 minutes can boost the memory five-fold, according to new research. Mail Online, March 23 2015

How Power Naps Can Turbocharge Your Memory. The Huffington Post, March 23 2015

How a short nap can improve your memory five-fold. Daily Express, March 23 2015

Links To Science

Studte S, Bridger E, Mecklinger A. Nap sleep preserves associative but not item memory performance. Neurobiology of Learning and Memory. Published online February 23 2015

Categories: NHS Choices

'4D' ultrasound shows effects of smoking on unborn babies

NHS Choices - Behind the Headlines - Tue, 24/03/2015 - 13:00

"Unborn baby shown grimacing in womb as mother smokes," is the somewhat misleading headline in The Daily Telegraph.

The news comes after researchers released dramatic images of babies in the womb taken using 4D ultrasound scanners. 4D scanners provide real-time moving images of babies in the womb.

Some newspapers have interpreted these images as showing distress caused by smoking. While smoking is certainly known to be harmful in pregnancy, the researchers may be reading too much into these images by claiming they show "grimaces" or expressions of pain in response to smoking.

The scans came from a small pilot study that showed differences between the movements of the unborn babies of four mothers who smoked, compared with the unborn babies of 16 non-smokers.

The paper says unborn babies touch their faces and move their mouths more in the earlier stages of their development, making these movements less often as they mature.

This study scanned babies between weeks 24 and 36 of pregnancy, and showed that babies carried by women who smoked appeared to move their mouths and touch their faces more than non-smokers' babies.

The implication is that this is a sign of slower development as a direct result of maternal smoking. But this has not been proven.

This study had a very small sample size, including just four smokers. And we don't know whether these observed differences in movement actually have any meaning in terms of the ongoing development of the unborn baby, or during infancy or childhood.

Still, we don't need any new research to tell us that smoking in pregnancy is harmful. Every cigarette you smoke contains more than 4,000 chemicals that will harm your baby.

Protecting your baby from tobacco smoke is one of the best things you can do to give your child a healthy start in life. It's never too late to stop smoking.  

Where did the story come from?

The study was carried out by researchers from Durham and Lancaster universities and James Cook University Hospital in Middlesbrough. We do not know who funded the study.

It was published in the peer-reviewed medical journal Acta Paediatrica.

Emotive images from the study were widely reproduced in the media. The Daily Telegraph suggested that the baby in the images was "grimacing" in response to cigarette smoke, while the Daily Mirror says the "dramatic pictures" show babies "suffering in the womb".

But the mother would not have been smoking in the hospital while being scanned, and we don't know the significance of the facial movements shown in the images, much less whether they represent suffering.

A case could be made that using the images to frighten mothers into quitting would be justifiable for the greater good, but it also wouldn't be entirely truthful or transparent.  

What kind of research was this?

This was a pilot observational study of a small number of pregnant women. It intended to see whether ultrasound scans could provide reliable information on subtle foetal movements (rather than asking mothers to count movements), and also see whether there are differences seen in the unborn babies of mothers who smoke.

This type of study can point to differences between different groups, but it cannot show what caused the differences. The researchers say a bigger study is needed to see if their findings are reliable and investigate them further. This study also can't tell us what the differences in movements mean for the development of the babies.

What did the research involve?

The researchers used 4D ultrasound to scan the unborn babies of 20 mothers, four of whom smoked. The babies were scanned four times from 24 to 36 weeks of pregnancy for 15 to 20 minutes at a time.

The scan is known as 4D because it provides detailed 3D-like moving images, time being the fourth dimension. 

Recordings were analysed for the numbers of times the babies moved their mouths and touched their faces.

The women filled in questionnaires at each scan to say how stressed they were feeling. They also completed a widely used depression questionnaire called the Hospital and Anxiety Depression Scale.

The ultrasound scans took images every half a second, producing detailed pictures of the babies' faces through time. Some scans were double-checked independently to confirm that the movement counts were accurate.

The researchers used standard methods to analyse the differences between smoking and non-smoking groups and how they changed over the four scans. They adjusted their results to take account of the babies' gestational age and sex, and the mothers' age, stress level and depression symptoms.

What were the basic results?

Babies whose mothers smoked (14 cigarettes a day on average) moved their mouths more often than babies whose mothers were non-smokers. This was true at the start of the study, and the gap widened as the study went on.

Babies whose mothers did not smoke reduced their number of mouth movements from their first to last scan by about 3% a week. This happened more slowly for babies whose mothers smoked, at 1.5% a week.

The results were less clear-cut for the number of times babies touched their faces. Researchers said the difference between the two groups was "borderline [statistically] significant", meaning they cannot be sure this was not down to chance.

However, the direction of the effect was similar – babies whose mothers smoked tended to touch their faces more often, and there was a decline in movement in both groups as the babies grew.

Mothers' stress levels also affected the baby's movements. Babies moved their mouths and touched their faces more often when their mothers reported higher stress levels.

All babies were born healthy, and there were no significant differences recorded between the babies born to smokers and non-smokers.

How did the researchers interpret the results?

The researchers say their study shows that the scanning technique they used provides a more sensitive way of assessing differences in babies' movements before they are born, compared with methods such as asking mothers to record how often they feel the baby move.

They say the comparison between smoking and stress levels shows that "smoking appears to be more important than stress" in terms of how it affects the baby's movements.

While they cannot be sure why the differences in face touching arise, the researchers suggest the babies may touch their faces to soothe themselves in a way that young infants have been seen to do after birth.

They also suggest the differences in mouth movements and face touching could be down to the rate at which the baby's central nervous system (brain and spinal cord) matures. Babies whose mothers smoke are thought to have slower-maturing nervous systems.

Conclusion

This pilot study looked at whether ultrasound scans could be a reliable way of assessing foetal movements. It then looked at whether movements differ between babies whose mothers smoke and those who do not.

The study found babies whose mothers smoked moved their mouths more often, and the rate at which they reduced their mouth movements was slow compared with babies whose mothers didn't smoke.

The main limitation of this study was its size – only four smokers and 16 non-smokers were included. This means the results are more likely to be down to chance than in a bigger study. We can't be sure that these results apply to all babies of smokers and non-smokers, and a bigger study is needed to confirm the results.

A further point is that if there are real differences between the movements of babies whose mothers smoke or don't smoke, we can't say exactly why these differences arise or what they mean for the baby.

The researchers have suggested reasons for the differences in movements, but this type of study is not designed to look at the reason behind the differences.

We need more research to investigate whether the differences seen in this study do represent slower development of the baby's nervous system, and whether they could have any meaning for the continued growth and development of the infant or child.

Another limitation is the potential influence of confounding – that is, any differences may not necessarily be a direct effect of smoking, but could be the result of the influence of other factors. The study did take into account the baby's gestational age and sex, or the mother's age, stress levels and depression symptoms, for instance.

However, other factors could have influenced the results, such as socioeconomic factors, whether the father smoked, or other health and lifestyle factors in the mother, such as diet, physical activity, BMI and alcohol intake. 

The photographs released to the media are from two 10-second scans of 32-week-old babies, one taken from a woman who smoked and one from a non-smoker. They are described as "illustrative". The first shows the baby covering its face with both hands, while the second shows the baby with a hand to its mouth.

The images are powerful and provoke an emotive result in most people, as the baby appears to be in distress. But it's important to bear in mind that these images may not be representative of the approximately 10 to 13 hours of scans taken. We cannot tell whether the babies pictured were distressed, contented, or showing another emotion.

Despite the limitations of this study, it is already well established that smoking during pregnancy has various harmful effects, both to mother and baby.

This small study found there may be differences in the movement of unborn babies of smoking and non-smoking mothers. Whether there are true differences, and whether they have any meaning or implications in terms of the baby or child's ongoing development, is something that needs to be examined in further larger studies.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Links To The Headlines

Unborn baby shown grimacing in womb as mother smokes. The Daily Telegraph, March 23 2015

4D ultrasound study shows harmful effects of smoking on unborn babies. The Independent, March 23 2015

4D ultrasound scans show the harmful effects of smoking during pregnancy on babies. Daily Express, March 23 2015

Revealed, what smoking does to an unborn baby: Remarkable images of foetus holding its face show how babies exposed to cigarettes may have delayed development. Mail Online, March 23 2015

Links To Science

Reissland N, Francis B, Kumarendran K, Mason J. Ultrasound observations of subtle movements: a pilot study comparing fetuses of smoking and non-smoking mothers. Acta Paediatrica. Published online March 12 2015

Categories: NHS Choices

News analysis: Angelina Jolie's surgery to 'cut ovarian cancer risk'

NHS Choices - Behind the Headlines - Tue, 24/03/2015 - 11:00

Writing in the New York Times, actress Angelina Jolie has announced she recently had her ovaries and fallopian tubes removed as tests showed she had an estimated 50% chance of developing ovarian cancer. This is because previous testing found she was carrying high-risk genes linked with ovarian as well as breast cancer.

This follows a previous announcement in 2013 when Ms Jolie announced she had undergone a double mastectomy (where both breasts are surgically removed) followed by breast reconstruction surgery. This was because the same high-risk genes gave her an 87% chance of developing breast cancer.

Jolie explained: "I had been planning this for some time. It is a less complex surgery than the mastectomy, but its effects are more severe. It puts a woman into forced menopause. So I was readying myself physically and emotionally, discussing options with doctors, researching alternative medicine, and mapping my hormones for estrogen or progesterone replacement.

"Regardless of the hormone replacements I’m taking, I am now in menopause. I will not be able to have any more children, and I expect some physical changes. But I feel at ease with whatever will come, not because I am strong but because this is a part of life. It is nothing to be feared."

 

What genes contribute to ovarian cancer risk?

BRCA1 and BRCA2 are faulty genes linked to ovarian cancer. They're also known to increase the risk of breast cancer.

Having a family history of ovarian cancer, especially if the cancer developed before the age of 50, could mean the faulty genes run in your family.

You may be at a high risk of having a faulty gene if you have:

  • one relative diagnosed with ovarian cancer at any age and at least two close relatives with breast cancer whose average age is under 60; all of these relatives should be on the same side of your family (either your mother's OR father's side)
  • one relative diagnosed with ovarian cancer at any age and at least one close relative diagnosed with breast cancer under the age of 50; both of these relatives should come from the same side of your family
  • two relatives from the same side of the family diagnosed with ovarian cancer at any age 

If you're at a higher risk of having a faulty gene, your GP can refer you for tests to check for faulty BRCA1 and BRCA2 genes.

Ovarian Cancer Action has developed a tool to help you check whether your family history puts you at risk of ovarian cancer

 

What does preventative surgery involve?

If testing suggests you have a high risk of developing ovarian cancer, your doctor may recommend a type of surgery called bilateral salpingo-oophorectomy. This is where both of your ovaries as well as your fallopian tubes are surgically removed.

This should significantly reduce your chance of developing ovarian cancer, though it will trigger the menopause if you have not already gone through it.

This can cause symptoms such as hot flushes and night sweats. Symptoms usually respond well to hormone replacement therapy (HRT). 

Alternative treatments are also available for women who cannot or do not want to use HRT.

What other steps can I take to reduce my risk of ovarian cancer? Stopping ovulation and the contraceptive pill

Each time you ovulate, your ovaries are damaged by the egg as it breaks through the surface of the ovary and is released into your reproductive system.

The cells that make up the surface of your ovaries divide and multiply rapidly to repair the damage caused by the egg. It's this rapid cell growth that can occasionally go wrong and result in ovarian cancer.

Anything that stops the process of ovulation can help to minimise your chances of developing ovarian cancer. This includes:

Diet and lifestyle

Research into ovarian cancer has found that the condition may be linked to being overweight or obese. Losing weight through regular exercise and a healthy, balanced diet may help lower your risk of getting ovarian cancer. Aside from this, regular exercise and a healthy, low-fat diet are extremely beneficial to your overall health, and can help to prevent all forms of cancer and heart disease.

 

Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Angelina Jolie Pitt: Diary of a Surgery. New York Times, March 24 2015

Angelina Jolie reveals she had ovaries removed after cancer scare. The Guardian, March 24 2015

Jolie Has Ovaries Removed After Cancer Scare. Sky News, March 24 2015

Angelina Jolie has ovaries and fallopian tubes removed. BBC News, March 24 2015

Categories: NHS Choices

'How I took back control of my drinking'

NHS Choices - Live Well - Mon, 23/03/2015 - 19:19
'How I took back control of my drinking'

Joanna Munro describes herself as the typical mother who enjoys a well-earned glass of her favourite tipple at the end of a trying day.

As someone who drank no more than a couple of glasses of wine a day, Joanna, 45, was by no means a heavy drinker. But one day, she realized that “wine o’clock” had become more of a habit than a pleasure.

She gave up alcohol for a month for Dry January to prove to herself she was still in control but she tells how she soon started noticing unexpected health benefits.  

Pleasure or habit?

“Back in December, I was a typical example of the mother who reaches for her first glass of rosé while simultaneously burning dinner, tripping over the dog, emptying the washing machine and resolving conflicts between the kids. Then I realized that "wine o'clock" had become an automatic reflex that wasn’t so much a pleasure as a habit. 

“I didn’t find an answer to my question on the internet, but I did find Alcohol Concern’s website and a challenge called Dry January. I liked the idea – an opportunity to prove to myself that I had more self-control than a four-year-old who’d been left alone in a Cadbury’s warehouse. If I was hooked, I’d be clawing my way up the curtains in despair within days.

“So I signed up. Over the month, my resolve was considerably strengthened by Dry January’s Facebook page and the determination and solidarity of those taking part. The challenge worked a charm because people can encourage each other and be accountable to each other.

“The aim was simple on paper: give up alcohol for one month. As I’m an eternal optimist, I added an hour of exercise every day for good measure. I quickly worked out a circuit through my local village. When attempting abstinence for the first time in 12 years, sunshine and great countryside proved ideal to lift this trainee teetotaler’s spirits.

Health benefits

“The first week, I rode the virtuosity wave. I was a disdainful diva, even declining champagne on the beach to toast in the New Year. By the middle of the second week, however, the queen of self-control and restraint was glowering, Gollum-like, over her glass of Perrier and lime as hubby savoured his beer.

“After two weeks the cold turkey wore off, and the first benefits kicked in. I was in bed snoring shamelessly before 10 and was awake before the alarm at 6.15am. My skin was looking better. I had more energy, and was proud of myself for sticking at it.

“Although weight loss wasn’t a decisive factor for me, I lost 5lbs (2.3kg) in the first month and I have now lost nearly 10lbs and banished three inches (7.5cm) of muffin top from my waistline. Like many other people on Dry January’s page, my problem was the inexplicable desire to replace my evening dose of wine with snacks in front of the TV.

“Yet in the long run, less wine meant less nibbles. I realized how alcohol opened up my appetite and made me reach for those salty nibbles.

"Less nibbles meant less weight. Not exactly rocket science, but a winning equation nevertheless.

The NHS recommends:

  • Men should not regularly drink more than 3-4 units of alcohol a day
  • Women should not regularly drink more than 2-3 units a day
  • If you've had a heavy drinking session, avoid alcohol for 48 hours

    "Regularly" means drinking this amount every day or most days of the week.

    Categories: NHS Choices

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