NHS Choices

Testing sense of smell may give early warning of Alzheimer's risk

NHS Choices - Behind the Headlines -

"A new four-point test has fine-tuned smell exams to check for Alzheimer's," the Mail Online reports. The testing is based on recognising and then recalling certain distinct smells, such as lemon or menthol.

Some people who scored badly on the test were later found to have early signs associated with Alzheimer's disease.

Previous research has shown people's sense of smell gets worse as they get older. People with dementia seem to have an even worse sense of smell and ability to identify smells.

But simple odour identification tests do not account for variation in different people's sense of smell.

Researchers in the US tested 183 people to see if they could identify 10 common smells, including lemon, mint and strawberry.

They then did a second test to see whether people could identify 20 smells and remember the 10 they'd smelled in the first test.

The second test was better at identifying people with Alzheimer's as well as early symptoms of dementia.

It also picked out people who had no signs of Alzheimer's, but who carried gene variants connected with the disease.

We now need further research in more people to be sure that the findings are correct.

If you do lose your sense of smell (anosmia), you shouldn't panic – there could be a relatively trivial reason behind it, such as chronic sinusitis. But it is the sort of symptom you should get checked out by your GP.

Where did the story come from?

The study was carried out by researchers from Massachusetts General Hospital, the University of North Carolina, Harvard School of Public Health, and Osmic Enterprises, all in the US. 

It was funded by grants from the US National Institutes of Health, the Wilkens Foundation and Harvard Neurodiscovery Centre.

The study was published in the peer-reviewed journal, Annals of Neurology.

The Mail Online seems to have misunderstood some aspects of the study. It says the participants were "patients at the Massachusetts General Hospital" who "were deemed to have an increased risk" of Alzheimer's disease.

In fact, they were a mix of volunteers aged over 65 and living at home. Ten of them already had Alzheimer's disease, but most were healthy.

The point of the study was to see whether the test could pick out people at increased risk, not to test people already known to be at increased risk.

The Mail Online story also mistakenly said the test could pick out those with a build-up of amyloid protein in their brains, but this study found no link between amyloid protein and the test results.

What kind of research was this?

This cross-sectional cohort study looked at how people performed on smell tests at one point in time.

Researchers wanted to see whether this was related to their mental health or other markers linked to Alzheimer's disease. 

What did the research involve?

Researchers recruited people taking part in a long-term study of ageing and dementia, and five people with dementia from a memory clinic.

They were given standard tests to identify dementia and early signs of dementia, known as mild cognitive impairment.

Some people also had brain scans and genetic testing for gene variants linked to dementia.

They took three tests to assess their sense of smell, memory for smells, and ability to discriminate between smells.

Researchers then looked at the results to see whether – taking account of possible confounding factors like age and education level or medical reasons for a poor ability to smell – the smell test results could predict people with dementia or at higher risk of dementia.

The three tests were:

  • 10 common smells – people were asked if they recognised the smell and if they could identify it from a list of four names
  • 20 common smells, including the 10 from the first test – people were asked if they'd smelled the odour in the first test and to identify it from a list of four names
  • 12 smells – two smells were presented one after the other, and people were asked to say whether they were the same or different

The first two tests, when used together, were called the POEM test, short for Percepts of Odor Episodic Memory.

Researchers used a battery of statistical tests to see which factors correlated with which. Their primary interest was whether the test results predicted people's diagnoses (normal, some concerns, mild cognitive impairment, or Alzheimer's disease).

They also wanted to see if the smell test results were linked to other early predictors of Alzheimer's disease, such as:

  • degeneration of certain regions of the brain
  • deposits of amyloid protein in the brain
  • gene variants thought to be more common in people with Alzheimer's disease
What were the basic results?

People who were cognitively normal or had only some concerns about their memory tended to do well on the POEM test.

And their results were significantly better than those of people with mild cognitive impairment or Alzheimer's disease.

When researchers looked at people who were cognitively normal but did worse than expected on the POEM test based on their results from the first (10 smells) test, they found these people were more likely to have:

  • a gene variant associated with Alzheimer's disease
  • thinner tissue in a part of the brain associated with memory (the entorhinal cortex)
  • worse logical memory scores over time

However, there was no link seen between the POEM results and deposits of amyloid protein in the brain.

We don't know if the people who did worse on smell tests went on to get Alzheimer's disease, as this was not part of the study.

A study with a longer-term follow-up period would be required to investigate this.

How did the researchers interpret the results?

The researchers said the POEM test needed to be confirmed in longer studies and different groups of people.

However, they said if these results were confirmed, the POEM test "may identify a subset of clinically normal participants at greater risk for developing the progressive memory symptoms" of Alzheimer's disease.

They say this could identify suitable people to take part in research of treatments that might prevent the disease. They also suggest the tests could be used to screen for Alzheimer's disease risk in the general population.

Conclusion

Sense of smell varies greatly from one person to another, and tends to decline as we get older. Lots of people can lose their sense of smell – either temporarily or permanently – after illness or an accident.

Having a poor sense of smell does not mean you're going to get Alzheimer's disease, and that's not what this study found.

People who already had Alzheimer's disease, not surprisingly, did poorly at identifying smells.

But smell detection ability alone did not differentiate between healthy people, those with some memory concerns, and those with mild cognitive impairment.

Only the POEM test, which looked at people's ability to both identify and remember smells, could do that.

For people without dementia or mild cognitive impairment, those who did less well at remembering smells compared with their ability to identify them were more likely to have previously identified risk factors for Alzheimer's disease.

These include a genetic variant more common in those with Alzheimer's disease and physical evidence of some degree of tissue thinning.

But we don't know whether these people did go on to get dementia, as the study only looked at a snapshot in time, not at what happened to people over time. It's important to remember, too, that this was a relatively small study.

We need to have these POEM test results validated by larger studies that follow people over time before we can say whether it is a useful way of identifying older people likely to develop Alzheimer's disease before they have any symptoms of confusion or memory loss.

If you're concerned about symptoms that might be related to Alzheimer's disease or other forms of dementia, see your GP.  

Read more about how dementia is diagnosed.

Links To The Headlines

Why sense of smell is the biggest tell-tale factor for Alzheimer's – and could be spotted 10 years before memory loss symptoms. Mail Online, November 14 2016

Alzheimer's early signs: Declining sense of smell could be first warning of decline, not memory loss. The Independent, November 15 2016

Links To Science

Albers AD, Asafu-Adjei J, Delaney MK, et al. Episodic Memory of Odors Stratifies Alzheimer Biomarkers in Normal Elderly. Annals of Neurology. Published online November 14 2016

First time flu infection may affect lifetime immunity

NHS Choices - Behind the Headlines -

"A person's chances of falling ill from a new strain of flu are at least partly determined by the first strain they ever encountered, a study suggests," BBC News reports.

Researchers created a modelling study, based on historic data, which aimed to look at the reasons why past flu epidemics of influenza A – commonly referred to as "bird flu" – have affected different age groups. It seems it comes down to the strains that were circulating when you were born.

Influenza A viruses carry two protein groups on their surface, H and N, which is how they are named, such as H1N1. It would appear that the H protein group, and its different strains, can imprint a lifelong immunity, or at least partial immunity, against that strain.

So for example, someone exposed to a H5 virus when they were born shouldn't be affected by any virus carrying an H5 strain, but may be affected by an H7 virus. The researchers call this "immune imprinting".

The findings may help in planning for flu outbreaks by estimating which age groups are most likely to be affected depending on what different strains of flu were prevalent when they were born.

 

Where did the story come from?

The study was carried out by researchers from University of California, University of Arizona, and Fogarty International Center in Maryland, US. The individual researchers received various sources of financial support, including from the National Institute of General Medical Sciences of the National Institutes of Health.

The study was published in the peer reviewed journal Science Magazine on an open-access basis so it is free to access online.

The UK's media coverage of the study was accurate.

The lead researcher Dr Michael Worobey, was widely quoted, as he used the metaphor for describing the protein groups as "lollipops": "if you were first infected with a virus from the 'blue lollipop' group as a kid, that won't protect you against this novel, 'orange' strain".

 

What kind of research was this?

This was a modelling study using data from known human cases of the influenza A viruses H5N1 and H7N9 to investigate the theory that an individual's first encounter with a virus of this group will confer lifelong protection against others of the same group.

Influenza A viruses are all known to infect wild birds, hence are often termed "bird flu". They are characterised by the presence of two proteins on their surface called haemagglutinin (HA) and neuraminidase (NA) and this is how they are named.

So H5N1 has five haemagglutinin groups and one neuraminidase group. There have been several outbreaks of bird flu over the past 10 years, causing hundreds of severe cases of illness and some fatalities. However, among the human cases there were notable differences in age distribution.

The possible reasons for this are not fully understood and this is what this study aimed to examine, by looking at documented human cases of H5N1 and H7N9.

 

What did the research involve?

The researchers looked at whether an individual's initial exposure to an influenza A virus influences their later exposure to H5 or H7 viruses.

They looked at people born in each year from 1918 to 2015 for six countries – China, Egypt, Cambodia, Indonesia, Thailand, and Vietnam – and looked at the influenza A virus they were likely to have been exposed to in each year.

They also gathered data on the known cases of H5N1 and H7N9 and their age distributions. Most of these documented cases are the severe or fatal ones – the total number of cases is unknown.

 

What were the basic results?

The researchers made a number of observations.

Looking at the influenza A viruses that people have been exposed to over the years, strain H1N1 dominated between 1918 and 1957. H3N2 has then clearly dominated since 1968, with the notable exception of the peaks of H1N1 – aka "swine flu" – coinciding with the pandemics of 1977 and 2009.

Looking at the two viruses of interest, there was a dominance of H7N9 among people born in the first half of the 20th century, and a dominance of H5N1 among people born from around 1968 onwards.

The researchers found "HA imprinting" explains future immunity. Across different subtypes, those with the same H protein group have more similarities than those with different protein groups. For example, viruses with group H1 show 83-98% similarity, compared to 76-82% similarity for influenza viruses between groups H1 and H2.

HA imprinting from child exposure was estimated to give 75% protection against severe infection and 80% protection against death from either H5N1 or H7N9.

They also estimated that people who become infected despite previous immunity, are probably at lower risk of infecting others because they have lower levels of viral shedding (the amount of viruses that are spread into the environment through actions such as sneezing).

They suggest that there has never been a true "virgin soil" flu pandemic because many people have protection from prior HA infection. That is, thankfully, there has never been a pandemic in which people had absolutely no level of immune protection against infection.

 

How did the researchers interpret the results?

The researchers conclude that their analysis of human cases of H5N1 and H7N9 shows strong evidence that childhood HA imprinting as a result of exposure gives lifelong protection against severe infection and death from these viruses.

They say "these findings allow us to develop new approaches for [influenza A virus] pandemic risk assessment, preparedness, and response but also raise possible challenges for future vaccination strategies."

 

Conclusion

This modelling study shows how the strains of influenza A – "bird flu" – circulating when a person is born give them lifelong protection against new subtypes with the same H protein groups. The researchers call this immune imprinting.

This may help to explain the high severity and mortality rate seen among certain groups. For example, the massive flu pandemic of 1918 was an H1N1 strain.

This had a very high fatality rate among young adults, which the researchers consider may have been because when they were born (between 1880 and 1900), H3 was the dominant strain. Therefore they had no protection when encountering H1. However, elderly adults of the same generation did have protection when H3 peaked in 1968.

These observations, however, aren't really too unexpected. It's already well known that the flu virus has many different strains; which is why people catch flu several times in their life, and why it's difficult to say the flu vaccine will definitely stop you catching flu (vaccines only cover the strain expected to be circulating that season). We also know that exposure to a specific virus gives us protection against the same if we encounter it again. So in that sense this isn't really "news" as such.

Nevertheless, as the researchers say, their findings could help in planning for future flu outbreaks, in knowing which age groups may be most at risk.

Though these are only modelling estimates so it's difficult to give certain answers. As the researchers acknowledge, analysis of documented cases of human flu typically looks at the more severe or fatal cases. Thousands of milder cases of flu may have missed medical attention.

The study also focused on examining cases in certain African and Asian countries. This may make it difficult to get the full picture of flu immunity.

For the general public there are limited immediate implications from this study. You can't change the year that you were born or the first strain of flu you were infected with.

You can reduce your risk of getting or spreading flu by following established hygiene advice. This includes regular handwashing, using tissues when you cough or sneeze then binning them after use.

The seasonal flu vaccine is available free on the NHS for pregnant women, anyone aged 65 and over, and adults with otherwise weakened immune systems or long-term health conditions.

A nasal spray form of the vaccine is now available; free of charge, for all children aged two to four, as well as older children with long-term health conditions.

Read more information about the seasonal flu jab for adults and the nasal spray for children.

Links To The Headlines

'First flu' affects lifetime risk. BBC News, November 11 2016

Will you get nasty flu this year? The year you were born can predict it, says study. The Guardian, November 10 2016

Why Philip's been VERY lucky not to catch the flu: Older generation have less immunity to modern strains. Daily Mail, November 11 2016

Why being born before 1968 could save you from a bird flu pandemic. The Daily Telegraph, November 10 2016

Your ability to survive a future flu epidemic depends on the year you were born. The Sun, November 10 2016

Links To Science

Gostic KM, Ambrose M, Worobey M, Lloyd-Smith JO. Potent protection against H5N1 and H7N9 influenza via childhood hemagglutinin imprinting. Science. Published online November 11 2016

Probiotics 'aid memory in people with Alzheimer's disease'

NHS Choices - Behind the Headlines -

"Probiotics found in yoghurt and supplements could help improve thinking and memory for people with Alzheimer's disease," The Daily Telegraph reports after a small study found people given the bacterial supplement had improved scores on brain function tests.

Probiotics are live bacteria and yeasts promoted as having various health benefits, and are often added to yoghurt.

An Iranian research team gave people with severe Alzheimer's disease a probiotic drink every day for 12 weeks, and then measured the changes in brain function test scores before and after the treatment.

They found small improvements after the probiotics were given compared with the placebo group, but it is unclear if these improvements were enough to be clinically useful or noticeable.

While the results are far from conclusive, they do add to a previous body of research that suggests there may be an association between gut health and brain function.

Exploring this association could lead to new insights and possible treatments for Alzheimer's and other forms of dementia.

There are no known safety concerns about probiotics. But based on the small size and short-term nature of this study, more rigorous research would be required before probiotics could be recommended as an evidence-based treatment for people with Alzheimer's disease.

Where did the story come from?

This Iranian study was carried out by researchers from Kashan University of Medical Sciences in Iran and was funded by a grant from the same university.

It was published in the peer-reviewed journal, Frontiers in Aging Neuroscience. This journal is open access, so the study is free to read online.

The UK media's coverage of this study was generally accurate, although this is early research and its limitations were not fully discussed.

What kind of research was this?

This randomised controlled trial (RCT) looked at whether probiotic supplements help improve cognitive function in patients with Alzheimer's disease.

It also investigated the effect of probiotics on biomarkers for inflammation and metabolism in the body.

Probiotics are often referred to as "good" or "friendly" bacteria, and are found in yoghurts and other dairy products.

Although probiotics have traditionally been recommended for people with gut conditions such as irritable bowel syndrome (IBS), recent research has shown they may benefit the brain, too.

This is because there may be a link between the gut and the brain along what's known as the micro biota-gut-brain axis.

This axis is a biochemical signalling pathway that runs between the brain and the digestive system. But its full role in terms of health outcomes is thought by many to not be fully understood. 

Double-blind randomised controlled trials like this one are thought to be the gold standard when it comes to investigating a potential association between an exposure and an outcome – in this case, between probiotic supplements and changes in cognitive function.

What did the research involve?

This 12-week trial recruited 60 patients with Alzheimer's disease with a mean age of 80. The participants were all matched for disease severity based on gender, age and body mass index (BMI).

They were then randomly assigned to two treatment groups (30 participants in each): the control group received plain milk, while the intervention group received probiotic milk (200ml a day).

The probiotic drink contained the bacterial strains Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium bifidum and Lactobacillus fermentum. 

The patients' cognitive function was measured before and after the 12-week trial using a Mini-Mental State Examination (MMSE). This scale is a 30-point questionnaire used extensively to measure cognitive impairment.

The test takes about 10 minutes to complete and assesses cognitive – or thinking – abilities such as attention, calculation, recall, language, and the ability to follow simple commands.

One example question is to ask people to count backwards from 100 in sevens. Any score greater than or equal to 24 points out of 30 indicates normal cognition.

Blood samples were also collected to assess levels of biomarkers for oxidative stress, which is an indicator of cell damage, as well as inflammation and metabolic profiles.

During the study, four patients from each treatment group died from old age. A total of 52 patients went on to complete the study. The data from these 52 patients was analysed and the findings were compared between the two treatment groups.

What were the basic results?

Overall, the 12-week treatment with probiotic supplements resulted in an improvement in the MMSE score of +27.9%, compared with a decrease of -5.03% in the control group.

In absolute terms this means that the control group deteriorated from 8.47 to 8.00, remaining severely impaired on the 30-point scale. Those taking probiotics improved from 8.67 to 10.57.

Although the difference was statistically significant, it is still a small change and suggests that even after taking probiotics everyone remained severely cognitively impaired.

The probiotic treatment also had a positive influence on a range of other blood markers that were of interest to the researchers.

However, changes in biomarker levels for oxidative stress, fasting plasma glucose (a marker of insulin sensitivity) and other lipid (fat) profiles remained insignificant.

It is not clear if these have a bearing on the development of Alzheimer's and how any link between them and drinking probiotics might be acting.

How did the researchers interpret the results?

The researchers concluded that, "The current study demonstrated that the probiotic administration for 12 weeks has favourable effects on MMSE score, MDA, hs-CRP, markers of insulin metabolism and triglycerides levels of the AD patients; however, the changes in other biomarkers of oxidative stress and inflammation, FPG and other lipid profiles are negligible." 

Conclusion

This randomised controlled trial looked at whether probiotic supplements help improve cognitive function in patients with Alzheimer's disease over 12 weeks.

It also investigated the effect of probiotics on biomarkers for inflammation and metabolism in the body.

It found treatment with probiotic supplements resulted in a small improvement in cognitive function compared with the control group.

But everyone remained severely cognitively impaired, and it's not clear if the change in score was clinically important in terms of function.

Although these are interesting findings, there are a few things to bear in mind:

  • This was a small trial involving 60 people. This intervention would need to be tested on a larger sample size to confirm the findings, as it's still possible that the change observed is a chance finding.
  • The participants were mainly female – only 12 male patients were involved – and everyone had severe dementia at the start of the study, so it's unclear whether probiotics are able to prevent dementia in the general population.
  • The trial was conducted for 12 weeks. As Alzheimer's is a progressive disease, it would be beneficial to monitor the long-term effects of probiotics in patients with Alzheimer's disease to know whether the improvement in cognitive function would last longer than three months.
  • The participants in the trial were an average age of 80. It would be interesting to see if the same effect was observed in patients at an earlier stage of Alzheimer's disease.

Dietary advice for people with Alzheimer's disease is the same for most other people – to eat a healthy, balanced diet.

Read more advice about caring for someone with Alzheimer's or other forms of dementia.

Links To The Headlines

Probiotics can help thinking and memory for people with Alzheimer's disease. The Daily Telegraph, November 10 2016

Eating probiotics 'boosts' brain power in Alzheimer's patients. The Sun, November 10 2016

Yoghurt 'can help treat Alzheimer's'. The Times, November 11 2016 (subscription required)

Links To Science

Akbari E, Asemi Z, Kakhaki RD, et al. Effect of Probiotic Supplementation on Cognitive Function and Metabolic Status in Alzheimer's Disease: A Randomized, Double-Blind and Controlled Trial. Frontiers in Aging Neuroscience. Published online November 10 2016

Scouts and Guides 'grow up to have better mental health'

NHS Choices - Behind the Headlines -

"Scouts and guides provide 'mental health boost for life'," BBC News reports. A study of adults with a scouting or guiding background found they were less likely to be anxious or depressed in later life.

But the difference in average mental health scores was quite small (2.2 points on a 1 to 100 scale). About 21% of people who'd been Scouts or Guides had scores that suggested a mood or anxiety disorder, compared to 25% of those with no history of involvement in Scouts or Guides.

The researchers also found the expected poorer mental health associated with coming from a lower social class did not seem to apply to children who'd been Scouts or Guides.

This may suggest that the inclusivity of both charity organisations, which welcome children from all backgrounds, may play a positive role in adulthood.

This type of research may be complicated by other factors. The researchers tried to take account of other factors, such as whether people took part in other clubs, but it is hard to be sure that other factors don't partly explain the findings.

While the overall results may appear modest, when it comes to mental health, every little helps.

Interestingly, the "Scouting principles" described by founder Robert Baden-Powell in the first decade of the 20th Century seem to chime with many of the steps that experts now think can lead to improved mental wellbeing.

These include connecting with others, lifelong learning, being mindful of the world around you and helping others.

 

Where did the story come from?

The study was carried out by researchers from the University of Edinburgh and the University of Glasgow and was funded by the Economic and Social Research Council.

The study was published in the peer-reviewed Journal of Epidemiology and Community Health on an open access basis, so the study is free to download (PDF, 351kb).

The UK media was enthusiastic about the possibility that Scouts and Guides were protected against poor mental health in middle age, and reporting was broadly accurate.

Many papers included quotes from individuals involved with the Scouting and Guiding movements, such as 18 year old Girlguiding member Emma Brodey, who said "Girlguiding is … for the girl. It offers a safe space where they can be themselves, build their confidence and escape from the ever-increasing pressures in their lives. Women tell us every week that their accomplishments and memories through guiding have lasted throughout their lives".

 

What kind of research was this?

This was a cohort study, intended to find out whether Scout or Guide participation in childhood was linked to adult mental health, and how this interacted with social class. Cohort studies are good ways to show links between factors, but it's much harder to show that one factor causes another.

 

What did the research involve?

Researchers used information from the UK's National Child Development Study, set up to study people born in one week in 1958.

A group of 9,790 people from this study were interviewed about their mental health in 2008, at age 50.

Researchers used information about the people from childhood onwards to adjust their figures for confounding factors, then looked to see whether they had better mental health if they'd been Scouts or Guides, and how this was affected by social class.

Only 4,020 people had complete records, so the researchers used statistical techniques to fill in the gaps. Some people were then excluded from the study if there was too little information about them. The researchers included 9,603 people in total.

Social class was assessed by their father's status, and educational aspiration by whether their parents wanted them to stay at school past the minimum leaving age of the time.

The research also looked at family history of mental health problems, and how often they played indoor or outdoor games or sports.

To try to take account of possible confounding factors, researchers looked at whether people took part in other clubs, voluntary groups or religious groups, and whether that was linked to their mental health.

They also looked at whether geographical areas with higher or lower Scout and Guide participation had differing mental health status.

They also considered if the amount of time people attended Scouts and Guides was linked to mental health (a so-called "dose response" where the effect size is in line with the amount of attendance – "the more the better").

 

What were the basic results?

The average mental health score (from a scale 0 to 100, where higher is better) was 74.8.

Researchers found 28% of the group had been Scouts or Guides, and for them:

  • average mental health score was 2.28 points higher
  • the chance of having a score of 65 or less, which the researchers used as a mark of having anxiety or mood disorder, was 18% lower, at 21 in 100 compared to 25 in 100 for people who weren't scouts or guides (odds ratio 0.82, 95% confidence interval 0.74 to 0.92)
  • the effect of social class, in which people with lower social class had poorer mental health aged 50, was less pronounced. People from lower social classes who'd been Scouts or Guides had as good or better mental health than those from higher social classes who hadn't been Scouts or Guides

Current membership of churches or voluntary organisations did not have any effect on mental health. However, surprisingly the researchers found that previous membership of a voluntary organisation was linked to a 27% increased chance of anxiety or mood disorder. Possible reasons for this were not explored.

 

How did the researchers interpret the results?

The researchers say their research "suggests that scout-guide attendance may be protective, instituting a resilience to stressful life events that may lead to mental ill health." They say that the relationship "does not appear to be explained by potential confounding factors".

They conclude: "encouraging interventions in youth that are low cost and available worldwide through existing institutional structures may be an important and cost-effective policy response" to poor mental health in later life.

 

Conclusion

The theory that being in the Scouts or Guides could set you up for good mental health for life is very attractive.

Scout and Guide membership is designed to help young people learn life skills, take part in communal activities and enjoy the outdoors, all of which are likely to help with better mental health.

However, there are a few issues to be aware of:

  • Observational studies can't prove beyond doubt that one factor causes another, even when the researchers try to account for alternative explanations for their findings.
  • The results threw up one odd finding – that past participation in voluntary groups greatly raised the risk of poor mental health, by much more than participation in Scouts or Guides reduced it. This surprising result casts doubt on the reliability of the other findings.
  • More than half of the participants in the study had missing data that had to be added in by researchers, making assumptions about the participants. This could introduce errors.
  • The researchers didn't find any evidence of a dose response – that the more people attended Scouts or Guides, the better their mental health.

However, whether or not these results are completely reliable, Scouts and Guides are low-cost, volunteer-run charity organisations which may offer young people support and life skills that could help them through life. To paraphrase the Scouting motto, it's always better to be prepared.

Links To The Headlines

Scouts and guides provide 'mental health boost for life'. BBC News, November 10 2016

Scouts and Guides are more likely to be happy adults: Getting members outdoors helps the chance of anxiety in middle age by a fifth. Daily Mail, November 10 2016

Being a scout or guide ‘can help improve mental health in later life’. The Independent, November 10 2016

Scouts and guides grow up to have better mental health. The Daily Telegraph, November 10 2016

Scout skills lower risk of anxiety. The Times, November 10 2016 (subscription required)

Links To Science

Didden C, Playford C, Mitchell R. Be(ing) prepared: Guide and Scout participation, childhood social position and mental health at age 50—a prospective birth cohort study. Journal of Epidemiology and Community Health. Published online November 10 2016

Teen vapers 'more likely to take up smoking'

NHS Choices - Behind the Headlines -

"Vaping raises likelihood of teenagers starting to smoke, study suggests," The Guardian reports.

A study of US teens found those who regularly vaped were more likely to progress to tobacco smoking than their non-vaping peers.

The study used questionnaires to assess e-cigarette and cigarette use in 3,000 adolescents aged 15.

The teenagers completed questionnaires twice: at the start of the study and six months later.

Researchers found there was an association between frequent use of e-cigarettes at the start of the study and smoking tobacco at follow-up.

Despite the association, it's difficult to say that the cigarette smoking was caused directly and independently by the use of e-cigarettes.

While the researchers took into account other risk factors for smoking, such as family smoking history, they did not look at all possible contributing factors.

For example, it could be the case that if e-cigarettes didn't exist, some teenagers may have started smoking tobacco anyway.

And these results are based on a small number of people.

The overall prevalence of smoking three or more cigarettes in the past month, or vaping three or more times, was below 5%.

Daily use of either, which may indicate a more serious habit, was also not examined.

E-cigarettes are best used as a quitting aid for people addicted to tobacco. Recreational use may be unwise.

While they are much safer than tobacco, e-cigarettes may still pose both short- and long-term health risks.

Where did the story come from?

The study was carried out by researchers from the University of Southern California Keck School of Medicine, the University of California, and the University of Pennsylvania Perelman School of Medicine, all in the US.

The research was funded by grants from the US National Institutes of Health. The authors report no conflict of interest.

The study was published in the peer-reviewed Journal of the American Medical Association (JAMA).

The UK media generally reported the story accurately, suggesting the link between e-cigarette use and smoking uptake was "tentative", and acknowledging that the number of adolescents who used e-cigarettes or cigarettes at all in the study was very small.

The media also acknowledged that other factors could have contributed to the uptake of smoking, such as the home environment.

The one exception to this measured reporting was on the Mail Online, which ran the headline: "E-cigarettes are a gateway to smoking". This implies that the research proved a direct causal relationship – but this is not the case.  

What kind of research was this?

This prospective cohort study followed adolescents over time to see whether e-cigarettes were associated with progression to cigarette smoking. It could be that using e-cigarettes is associated with the beginnings of a smoking habit.

But as some adolescents who smoke cigarettes use e-cigarettes as an aid to help them quit, it could be that those who use e-cigarettes are more likely to cut back on how much they smoke over time.

The researchers therefore wanted to see what the associations were between e-cigarettes and subsequent smoking frequency and heaviness.

A prospective cohort study is the best way of examining whether a particular factor is linked with a particular outcome.

But it can be difficult to account for all other variables that may be involved – for example, previous smoking, the frequency of other risk behaviours, or other environmental influences.

For this reason, cohort studies cannot prove cause and effect.

A randomised controlled trial, which could prove cause and effect, would not be ethical because we know smoking has harmful effects.

What did the research involve?

The researchers included students from 10 public high schools in Los Angeles County, California who were already enrolled in a longitudinal study.

The analysis used data from 3,084 students who completed surveys twice: once at the start of the study and again six months later. Their average age was 15.5 at baseline.

The surveys categorised e-cigarette use at baseline into "never", "prior" (ever used, but not in the previous 30 days), "infrequent" (1 to 2 days during the past 30 days), or "frequent" (3 or more days in the past 30 days).

Smoking use was also recorded at baseline and follow-up. Smoking frequency was categorised into "non-smoker", "infrequent smoker" (1 to 2 days in the previous 30 days) or "frequent smoker" (3 or more days in the past 30 days).

The amount smoked was categorised into none, less than one, one, or two or more cigarettes a day on smoking days.

The researchers assessed the association between e-cigarette use at baseline and how often and how heavily teenagers smoked at the follow-up stage.

The results were adjusted for confounders, including:

  • age
  • sex
  • ethnicity
  • highest parental education
  • whether the student lived with both parents
  • ever used alcohol or drugs
  • ever used any combustible tobacco product
  • family history of smoking
  • depressive symptoms
  • impulsive behaviour
  • sensation seeking
  • peer smoking
  • smoking susceptibility
  • smoking expectancies
What were the basic results?

At follow-up, those who had used e-cigarettes more frequently at baseline were more likely to have become smokers.

Frequent e-cigarettes use was associated with a subsequent increased possibility of frequent tobacco smoking (odds ratio [OR] 1.37, 95% confidence interval [CI] 1.16 to 1.61) and heaviness (OR 1.26, 95% CI 1.07 to 1.48).

Of those who had:

  • never used e-cigarettes – 0.9% were infrequent smokers and 0.7% were frequent smokers
  • used e-cigarettes at some point prior to the study – 4.1% were infrequent smokers and 3.3% were frequent smokers
  • used e-cigarettes infrequently at baseline – 9% were infrequent smokers and 5.3% were frequent smokers
  • used e-cigarettes frequently at baseline – 11.6% were infrequent smokers and 19.9% were frequent smokers

These trends were found to be stronger for those who had not been smokers at baseline (OR 2.51, 95% CI= 2.30 to 2.75).

How did the researchers interpret the results?

The researchers concluded "vaping more frequently was associated with a higher risk of more frequent and heavy smoking six months later".

They added: "Although some youths use e-cigarettes for cessation purposes, vaping was not associated with smoking reductions in baseline smokers.

"However, because the reason for vaping was not assessed, further investigation is required."

Conclusion

This research shows an association between using e-cigarettes at baseline and smoking frequency six months later among adolescents in US high schools.

The study has several strengths, including:

  • data was collected prospectively, meaning the researchers did not know the outcomes at the start of the study
  • adolescents were followed up over six months, which is a reasonable time period

However, the use of e-cigarettes and cigarette smoking was measured by self-reporting, and may be inaccurate.

While some factors were accounted for, it is difficult to account for all factors that may make smoking more likely.

These could include engaging in other risky behaviour or living in a home environment where teens are exposed to e-cigarettes or cigarette smoking.

Although it was a reasonably large sample size, with data from more than 3,000 adolescents, the number of teens who actually reported using e-cigarettes or cigarettes was low and therefore a small sample to base any conclusions on.

The categories used were fairly broad – "prior" use included people who had used e-cigarettes just once. "Frequent" users included those who used e-cigarettes three times in the previous month, which could be considered fairly low.

This study looked at students from US high schools, and the findings may not have as much relevance in the UK.

Find out more about quitting smoking if you're a teenager.

Free stop smoking treatments are available for both adults and children aged 12 to 18. Get more advice about quitting smoking.

Links To The Headlines

Vaping raises likelihood of teenagers starting to smoke, study suggests. The Guardian, November 8 2016

E-cigarettes ARE a gateway to smoking: Experts say high usage leads teenagers 'to take up the real thing'. Mail Online, November 8 2016

Links To Science

Leventhal AM, Stone MD, Andrabi N, et al. Association of e-Cigarette Vaping and Progression to Heavier Patterns of Cigarette Smoking. JAMA. Published online November 8 2016

Hopes raised that Zika virus could be treated in the womb

NHS Choices - Behind the Headlines -

"Scientists say they may have found a way to protect babies in the womb from the harmful effects of Zika," BBC News reports.

Researchers have had success using antibody therapy to treat mice when they were still in their mothers' womb.

There is evidence that Zika virus, which has become widespread in South America recently, can damage the development of babies in the womb. One of the most striking birth defects associated with Zika is babies being born with abnormally small heads and brains (microcephaly).

The hope is that by treating babies in the womb it may be possible to prevent, or at least reduce the extent of, birth defects.

The study involved isolating strains of antibodies (infection-fighting proteins) from the blood of people who'd recovered from Zika. Scientists picked the antibodies that were most active against several strains of the virus. They then tested their effect on pregnant mice infected with Zika.

The mouse foetuses were much more likely to survive if their mothers had been given antibodies, and there was less evidence of damage to the foetus or placenta.

Results in mice cannot tell us whether the treatment will be safe or effective in humans. So the researchers say the treatment should next be tested on monkeys, as their pregnancies and reactions to Zika virus are more similar to humans.

The need for effective Zika treatments is pressing as a study from earlier this summer estimated the current epidemic would last for at least three more years.  

Where did the story come from?

The study was carried out by researchers from Vanderbilt University Medical Center in Nashville and Washington University School of Medicine in the US.

It was funded by the US National Institutes of Health and grants from the charitable institutions Burroughs Wellcome Fund and the March of Dimes.

The study was published in the peer-reviewed journal Nature on an open-access basis so it's free to read online (PDF, 8.5Mb).

BBC News covered the main findings of the study accurately and made it clear that the treatment is not yet ready to be used in humans.

 

What kind of research was this?

This was experimental research carried out on mice in a laboratory.

Research in mice is a common early step when scientists are developing a treatment, but it doesn't tell us whether the treatment will be safe or effective in humans.
 

What did the research involve?

Researchers analysed blood from three people who'd had Zika, and isolated antibodies that seemed to bind to the Zika virus and inhibit its spread. They tested the most promising antibody as a treatment for mice infected with Zika virus, and also on pregnant mice infected with the virus.

They compared results for those given the antibody treatment and those given an inactive treatment.

Because mice have natural resistance to Zika virus, the researchers had to give them a treatment that suppressed their immune system and made them more vulnerable to the infection.

After treatment, researchers checked to see how long the mice survived, how many of the mouse pregnancies survived, and how much virus was found in the placenta or the mice brains.

They also tested giving the treatment before the mice were infected with Zika, on the same day, or five days after infection.

 

What were the basic results?

Mice treated with antibodies on the day after infection all survived for at least 20 days, while only 40% of untreated mice survived Zika infection for 20 days.

Later treatment was less successful, but mice treated five days after infection were still much more likely to survive.

Almost all mouse pregnancies survived up to 13 days where the mother had been treated with antibodies a day before being infected with Zika virus, while most pregnancies of untreated mice did not survive Zika virus infection.

When the researchers looked at tissues from the mice at the end of the study, they found much higher concentrations of Zika virus in the head of the mouse foetus and the foetal placenta, in untreated mice, compared to those treated with antibodies.

Levels of the virus were also higher in the brains and blood of the mice mothers who didn't have antibody treatment.

 

How did the researchers interpret the results?

The researchers say they've shown that antibody therapy, either before or after exposure to Zika virus, "reduced infection in mothers, and in placental and fetal tissues." Importantly, they say that "the extent to which these observations in mice translate to humans remains unclear", and recommend further animal studies in monkeys.

They say that if these results were positive, antibody treatment could be developed as a way of treating Zika infection during pregnancy.

 

Conclusion

For most people, Zika virus infection causes a mild flu-like illness. But it can cause serious damage to unborn children, if their mothers catch the virus while they are pregnant.

At present, there's no treatment that can help protect these babies against the effect of the virus, so news that a treatment may be on the way is welcome.

However, this research is in the very early stages. Mice and humans react very differently to Zika virus, and there are important differences in the structures of mouse and human bodies during pregnancy.

This means we don't know whether this treatment would work in the same way, or if it would even be safe for humans. Much more work is needed before this is a viable human treatment.

For now, the best thing you can do is to try to avoid becoming infected in the first place – especially if you're pregnant.

Pregnant women are being advised to postpone non-essential travel to areas with active Zika virus transmission. If you travel to an affected area, you can reduce your risk of catching the virus by using insect repellent and wearing loose clothing that covers your arms and legs.

Public Health England (PHE) provides regular updates about the current spread of the disease.

Links To The Headlines

Zika therapy 'works in the womb'. BBC News, November 8 2016

Links To Science

Sapparapu G, Fernanadez E, Kose N, et al. Neutralizing human antibodies prevent Zika virus replication and fetal disease in mice. Nature. Published online November 7 2016

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