"Women who douche are almost twice as likely to get ovarian cancer," Metro reports after a study of more than 40,000 women from the US and Puerto Rico found a significant link between douching and ovarian cancer – almost twice the risk of no use.
Vaginal hygiene is important – the use of plain unperfumed soaps to wash the surrounding areas is advised, while the vagina cleans itself with natural secretions.
But a douche flushes water up into the vagina and clears out natural secretions designed to keep the vagina healthy, which may increase the risk of infections.
There are concerns some douching products could introduce phthalates – chemicals that may disrupt hormone regulation – into the reproductive tract, which could increase the risk of ovarian cancer.
Concerns have also been raised that genital talc, often used in combination with douching, may increase cancer risk. But as we discussed earlier this year, evidence about this link is inconclusive. This study did not find a significant link for talc use.
Although this appears to be a large study, the number of women with ovarian cancer and a history of douching or talc was small, at just 40 people. This reduces confidence in the results.
Still, why take the risk at all? In a recent interview with NHS Choices, Professor Ronnie Lamont, spokesperson for the Royal College of Obstetricians and Gynaecologists said: "I can't think of any circumstances where douches are helpful."Where did the story come from?
The study was carried out by researchers from the National Institute of Environmental Health Sciences in the US, who also provided funding for the study.
It was published in the peer-reviewed journal, Epidemiology.
The study has been reported widely and accurately in the UK media. For example, The Independent explained the study cannot prove causality because a "precise link between the two is unknown, as correlation does not necessarily indicate causation.
"Other factors could be at play, including that women who notice discomfort or infections in their genital area are more likely to douche while also indicating poor ovarian health."
Many sources, such as The Sun, also made the point that women "should NEVER douche".What kind of research was this?
This prospective cohort study followed women without ovarian cancer over an average of 6.5 years.
It aimed to see if women who developed ovarian cancer over the course of the study were more likely to perform douching or use talc on their vaginas.
This type of study is still only able to find associations and cannot prove cause and effect, but it is the most appropriate study design for investigating whether a behaviour appears to be risky or not.
But the gold standard in study designs – a randomised controlled trial – would be unethical as it would expose participants to a potential risk.What did the research involve?
This study looked at data from women from the US and Puerto Rico involved in the Sister Study, which, as the name suggests, is an ongoing cohort study involving sisters originally set up to look at breast cancer risk factors.
Women aged 35 to 74 years who were free of breast cancer and had a full or half-sister with breast cancer were enrolled in the study in 2003 and followed up until 2009.
At the start of the study participants completed telephone interviews, which included questions on their reproductive history, health conditions and lifestyle factors.
Women were excluded if they had their ovaries removed or ovarian cancer, or had no follow-up information.
The women also completed a questionnaire on their personal care, including douching and talc use in the previous 12 months. Participants were grouped as "never used" or "ever used" for the analysis.
Follow-up questionnaires were completed every two to three years and collected information on the women's health.
In July 2014 the researchers analysed data to establish the incidence of ovarian cancer. Hazard ratios were calculated controlling for the effects of possible confounders, including menopausal status, duration of oral contraceptive use, and body mass index.What were the basic results?
A total of 41,654 women were included in the analysis and followed for around 6.6 years. During the follow-up period 154 participants reported a diagnosis of ovarian cancer.
Douching in the 12 months before study entry was reported in 20% of those with a diagnosis of ovarian cancer and 13% of non-cases.
Talc was used in the 12 months before the study start by 12% of women who developed ovarian cancer and 14% of those who did not.
This meant there was no statistically significant association between talc use and ovarian cancer (HR 0.73; CI 0.44 to 1.2).How did the researchers interpret the results?
The researchers concluded that, "Douching but not talc use was associated with increased risk of ovarian cancer in the Sister Study."Conclusion
This cohort study investigated the association between ovarian cancer and both douching and talc use.
Using participants in the Sister Study, the researchers found a significant link between douching and ovarian cancer – almost twice the risk of no use. No significant link was seen for talc use.
The results need to be viewed with caution, however, as they are based on small numbers: just 40 women with ovarian cancer who had douched or used talc.
The study has other important limitations, but the main concern is it is not able to prove direct cause and effect. It may be that women with irritation or poor vaginal health would be more likely to use douching methods.
And although the researchers attempted to control for various confounders that may be influencing the link, it is possible these have not been fully accounted for and other health and lifestyle factors were missed.
Crucially, the researchers did not adjust their results to take into account the fact women who developed ovarian cancer were more likely to have a first-degree family history of ovarian cancer and more than one first-degree relative with breast cancer. Nor did they account for smoking, another risk factor for ovarian cancer.
The International Agency for Research of Cancer has classified genital talc as a possible carcinogen. So far there have been mixed results from other studies assessing the link, and further research in the form of good-quality prospective studies would be required to confirm this.
Vaginal hygiene is important to most women. But it is recommended that perfumed soaps, gels and antiseptics are avoided, as they can affect the healthy balance of bacteria and pH levels, and cause irritation.
A douche flushes water up into the vagina, clearing out vaginal secretions – this means using a douche can disrupt the normal vaginal bacteria and may increase risk of infections.
The use of plain, unperfumed soaps to wash the surrounding areas is advised, and the vagina will clean itself with natural secretions.
Links To The Headlines
Women who douche are almost twice as likely to get ovarian cancer. Metro, August 3 2016
Links To Science
Gonzalez NL, O'Brien KM, D'Aloisio AA, et al. Douching, Talc Use, and Risk of Ovarian Cancer. Epidemiology. Published online June 20 2016
"Large number of young people experience sex problems," The Guardian reports. In one of the largest UK surveys of its kind, 1 in 10 young men and 1 in 8 young women reported having persistent distressing sexual problems.
Commonly reported problems included premature ejaculation in men, problems reaching climax in women, and a general lack of interest in sex in both genders. The survey found 9% of men and 13% of women experienced a sexual problem they found distressing.
Concern about young people and sex tends to focus on preventing unwanted pregnancies and sexually transmitted infections (STIs), say the study authors, but less is known about how young people fare in terms of sexual well-being.
The researchers used information from 2,392 people aged 16 to 21, interviewed in 2010 to 2012.
While problems with sexual dysfunction are usually associated with older adults, it would seem that they are also a cause of concern in the young. This could lead to problems in the future as a distressing sexual experience in early adulthood could trigger long-term issues.
The researchers suggest that sex education shouldn't just focus on the negatives (STIs, unwanted pregnancies, and so on), but also provide practical advice on how to make sex better. This might prevent these problems from becoming lifelong difficulties.
Whatever your age, if you are having problems with your sexual relationships, talk to your GP. Good sexual health isn't just about avoiding infection or pregnancy. Having a fulfilling sex life is just as important.
Where did the story come from?
The study was carried out by researchers from the London School of Hygiene and Tropical Medicine, University of Glasgow, University College London and the University of Southampton. It was funded by the Medical Research Council and Wellcome Trust.
The Guardian, The Independent, and BBC Newsbeat covered the story accurately, featuring interviews with the lead researcher and other sexual health experts, who called for more attention to be given to sexual satisfaction and pleasure in sex education.
What kind of research was this?
This was a cross-sectional survey, designed to be representative of the UK's population as a whole. For this study, they looked at the data from people aged 16 to 21.
They wanted to see how common sexual problems are for people this age.
The larger study included people aged 16 to 74 and results were reported elsewhere. A cross-sectional survey is a "snapshot" of time, so we don't know whether people carried on having problems, or whether their experiences changed over time.
What did the research involve?
Researchers randomly selected 15,162 people – of all ages – within geographical areas chosen to give a balanced representation of the UK as a whole. They asked people a broad range of questions, including about their sexual experiences, in visits to their homes. They then "drilled down" to look in further detail just at the information provided by the 2,392 women and men aged 16 to 21.
More sensitive questions in the survey were asked using a computer system, where people filled in the answers themselves, without the researchers seeing the answers. This was done to encourage people to give truthful answers, without feeling embarrassed.
People who said they'd had sex in the last year were asked if they'd had these problems, lasting for a period of three months or more:
- lack of interest in having sex
- lack of enjoyment in sex
- anxiety during sex
- physical pain as a result of sex
- no excitement or arousal during sex
- not reached a climax (experienced an orgasm) or taking a long time to reach a climax despite feeling excited or aroused
- reached a climax (experienced an orgasm) more quickly than you would like
- uncomfortable vaginal dryness
- trouble getting or keeping an erection
They were then asked if they'd felt distressed as a result of these problems, and whether they'd asked for help from friends, family, through the media, or health professionals.
What were the basic results?
Sexual problems were relatively common among teenagers and young adults, although not as common as in the general population. Women were more likely to report sexual problems:
- 44% of women aged 16 to 21 had experienced a sexual problem, compared to 51.2% of women in the general population
- 33.8% of men aged 16 to 21 had experienced a sexual problem, compared to 41.6% of men in the general population
Of the problems causing distress, inability to reach orgasm was the most commonly experienced problem for women (6.3% said this problem affected and distressed them), and climaxing too soon the most commonly experienced problem among men (4.5% said this affected and distressed them).
Other common distressing problems for women were lack of interest in sex (22% reported this, with 5.3% saying they'd experienced and been distressed by it) and feeling physical pain during sex (9% experienced this, with 3.2% saying they'd been distressed by it). Between 8% and 10% of women reported feeling anxious during sex, experiencing no arousal or getting no pleasure from sex.
Men were less likely to report distressing problems. The main distressing problem other than climaxing too soon was difficulty getting or keeping an erection (7.8% experienced this and 3.3% said they'd been distressed by it).
Women were more likely to seek help for problems than men, although few of either gender sought advice from health professionals (7.9% of women and 3.6% of men). Most people who sought help looked to friends or family.
How did the researchers interpret the results?
The researchers concluded: "If we wish to improve sexual well-being in the population, we need to reach individuals and couples as they embark on their sexual careers, to prevent lack of knowledge, anxiety, and shame turning into lifelong sexual difficulties." They said their data gave a starting point for this work.
They suggested that better sexual education is needed to "debunk myths, discuss pleasure" and emphasise the importance of communication and respect in relationships. In addition, they said, given how common sexual problems seem to be in this group, it "may be appropriate" for healthcare providers to discuss sexual function with young people who attend for contraception or sexually transmitted infection screening.
The survey results show that sexual problems are relatively common among young people. The findings are perhaps not surprising, but suggest an unmet need for advice and support around sexual function and enjoyment, as well as the more traditional concerns of preventing unwanted pregnancy and infections.
Sex education is not compulsory for non-maintained schools in the UK, although pressure is mounting to make it so. Much traditional sex education focuses on contraception and safer sex practices.
There have long been calls for sex education to also include discussions of sexual pleasure and what makes for a happy sex life. Previous research has found that young people with good sexual function are more likely to protect themselves against sexually transmitted infections and unwanted pregnancy.
There are some limitations to the research. Although the researchers tried to balance their survey population to be representative of the UK as a whole, only 57.7% of people aged 16 to 74 asked agreed to take part. It's possible that people who didn't take part had sexual experiences that differed in some way from those who did take part. This would make the survey results less applicable to the UK as a whole. However, younger people who were asked to take part were more likely to do so (65.8% of 16 to 44 year olds).
The survey also relies on people answering questions truthfully and was carried out in a way that maximised the chances of this happening. But some people may have felt embarrassed to admit to problems, even without the interviewers being able to see their answers.
If you are having a problem then it is recommended to see your GP. While the prospect may seem embarrassing, they are trained to deal with problems with sexual dysfunction.
Links To The Headlines
Large number of young people experience sex problems, study finds. The Guardian, August 3 2016
More than one in 10 young people have recently suffered a distressing sexual problem. The Independent, August 3 2016
'Distressing sexual problems' affecting at least one in 10 young men and women. BBC News, August 3 2016
Links To Science
Mitchell KR, Geary R, Graham C, et al. Sexual Function in 16- to 21-Year-Olds in Britain. Journal of Adolescent Health. Published online August 2 2016
"Ditch sausages for a longer life," The Telegraph advises after a new study found swapping animal sources of protein in favour of plant sources was linked to a longer lifespan.
Researchers looked at previously recorded data on health outcomes and diet for more than 130,000 US health professionals.
They found animal protein intake was weakly linked to an 8% higher risk of death, particularly from cardiovascular diseases, such as a heart attack, whereas plant protein was associated with a 10% lower risk of death.
However, an increased risk of death was only seen in people who also had at least one other unhealthy lifestyle factor, such as smoking, heavy alcohol intake, being overweight or obese, and physical inactivity.
This highlights an important limitation of studies like this – it's unable to prove that high animal protein intake has directly and independently caused the increased risk of death. It's not possible to rule out the role of other unhealthy lifestyle factors that also may have an influence.
Other limitations are the specific population group of health professionals, two-thirds of whom were women, which may not be representative of everyone.
As the current body of evidence stands, as well as considering this latest study, it would seem to be a good idea to stick to the existing recommendations about limiting your consumption of red or processed meat to no more than 70g a day.Where did the story come from?
The study was carried out by researchers from a variety of institutions in the US and Italy, including the TH Chan School of Public Health, the Department of Medicine at Harvard University, the Broad Institute at Massachusetts Institute of Technology, and the University of Southern California, all in the US, and the Institute of Molecular Oncology in Italy.
It was funded by grants from the US National Institutes of Health.
Generally, the media coverage around this topic was fairly accurate. However, the Daily Mail reported that, "replacing red meat with vegetables, nuts and cereals saw the biggest drop in death rates", which is not quite the case, as vegetables as a specific group were not included in the food groups used to define plant protein.
Also, The Telegraph stated with confidence that "switching 19g of animal protein – the equivalent of a sausage or a few slices of bacon – for nuts, vegetables or wholegrains significantly cut the risk of early death".
Such precise predictions are arguably unwise given the notoriously complex interplay between diet, health and lifestyle.
BBC News did point out that if there is a benefit to eating plant protein, nobody really knows why this would be the case. A mystery worth investigating, perhaps?What kind of research was this?
This was an analysis of two prospective cohort studies: the Nurses' Health Study and the Health Professionals Follow-up Study. It aimed to examine whether animal and plant protein intake was linked to mortality risk.
Studies like this are useful for assessing the influence of a specific exposure (in this case, diet) and outcome (mortality), but cannot confirm cause and effect.
We are unable to rule out confounding from many other health and lifestyle factors that may be involved in the link.What did the research involve?
Researchers analysed data obtained from 131,342 participants (85,013 women [65%] and 46,329 men [35%]) from two long-standing ongoing studies in the US: the Nurses' Health Study and the Health Professionals Follow-up Study.
The Nurses' Health Study included 121,700 female nurses aged 30-55 recruited in 1976. This study used follow-up data collected between 1980 and 2012.
The Health Professionals Follow-up Study included 51,529 male healthcare professionals aged 40-75 in 1986. Follow-up data was collected up to 2012.
Data on dietary intake was collected through food frequency questionnaires, which were conducted every four years. The questionnaires asked participants on average how often they consumed a standardised portion of different foods in the previous year.
Within this, animal and plant protein intake was assessed. Animal protein was described as processed and unprocessed red meat, poultry, dairy products, fish and egg. Plant protein included mainly bread, cereals, pasta, nuts, beans and legumes.
Deaths were identified by linkage with the National Death Index. Cause of death was obtained from death certificates or medical records. All-cause mortality rates were calculated for deaths from cardiovascular disease, cancer and other causes.
The researchers then looked for links between animal and plant protein intake with different causes of death. The results were stratified by age and lifestyle factors.What were the basic results?
The average (median) protein intake among participants was 14% for animal protein and 4% for plant protein.
After adjusting for lifestyle and dietary risk factors, animal protein intake was weakly associated with higher mortality, particularly cardiovascular mortality (hazard ratio [HR] 1.08. 95% confidence interval [CI]: 1.01 to 1.16) – the association is described as weak as it just reaches the level of statistical significance.
Plant protein was associated with lower mortality (HR 0.90. 95% CI: 0.86 to 0.95).
However, these associations were observed only in participants with at least one other unhealthy lifestyle factor, and was not seen in those without any of these risk factors.
Replacing animal protein with plant protein resulted in lower mortality. For example, substituting 3% of energy from plant protein with an equivalent amount of protein from processed red meat was associated with a third lower all-cause mortality (HR 0.66. 95% CI: 0.59 to 0.75).
Slightly lower risk reductions were seen when substituting for unprocessed meat, poultry, fish, egg and dairy.How did the researchers interpret the results?
The researchers concluded that, "High animal protein intake was positively associated with mortality, and high plant protein intake was inversely associated with mortality, especially among individuals with at least one lifestyle risk factor.
"Substitution of plant protein for animal protein, especially that from processed red meat, was associated with lower mortality, suggesting the importance of protein source."Conclusion
This analysis of two prospective cohort studies aimed to examine whether our intake of animal and plant protein is linked to our mortality risk.
It found evidence that animal protein intake was weakly associated with higher mortality, particularly cardiovascular mortality, whereas plant protein was associated with lower mortality.
However, the association with mortality was only seen in those with at least one other unhealthy lifestyle factor: smoking, heavy alcohol intake, being overweight or obese, and physical inactivity.
This suggests that it's not meat alone that has the effect – it seems to be more a compound effect when high meat intake is combined with other unhealthy lifestyle factors.
This reinforces the main inherent limitation of this study – it's an analysis of data from observational studies, which are unable to prove that animal protein intake has directly and independently led to an increased risk of death.
The authors attempted to control for various potential health confounders. As they've demonstrated, some of them also had an influence on risk. But it's not possible to fully take account of or rule out the influence of all unhealthy lifestyle factors.
The results may not be generalisable to the general population for several reasons. The two cohort studies only included health professionals, who may be more health conscious as a result of their jobs.
There was not an even gender representation, as roughly two-thirds of participants were women and one-third men. The results also do not represent children and younger adults.
Although food frequency questionnaires are a validated tool for measuring dietary intake, results are not always representative of long-term eating and drinking habits.
Similarly, other self-reported data on smoking, alcohol or physical activity may not be completely accurate.
We may think that plant protein would include high amounts of vegetables. But the foods most commonly consumed in this group were actually carbohydrates and beans.
If you choose to eat a vegetarian or vegan diet, whether it's for health concerns, ethical reasons, or both, it is possible to get all the nutrients you need, provided you eat a wide range of foods.
Read more about vegetarian and vegan diets.
Links To The Headlines
Ditch sausages for a longer life, say Harvard scientists. The Telegraph, August 1 2016
BEANS OR YOU'RE TOAST: Ditch red meat for plant protein to live longer, say experts. The Sun, August 2 2016
Plant proteins link to longer life. BBC News, August 1 2016
Links To Science
Song M, Fung TT, Hu F, et al. Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality. JAMA Internal Medicine. Published online August 1 2016
"Hope for faster treatment for depression after scientists discover why antidepressants can take months to work," the Mail Online reports. New research suggests manipulating the brain's Gα protein may accelerate the effect of the drugs.
Currently the most widely used antidepressants belong to a class called selective serotonin reuptake inhibitors (SSRIs). These are thought to increase levels of a neurotransmitter called serotonin, which can improve mood and emotion.
However, SSRIs can be slow to act, taking from one to four weeks before any benefits start to take effect. Why they can be slow to act is poorly understood.
The research suggests a protein in the brain – called the Gα protein – acted as a kind of chemical roadblock, slowing the redistribution of SSRIs to the brain cells that will respond to it.
This was an early-stage experiment in rats. We don't know that this provides the whole answer, and findings would need to be confirmed in humans.
It is also important to stress that when it comes to antidepressants, more doesn't mean better. Taking more than your recommended dose can be extremely dangerous.
While antidepressants can be useful in helping relieve the symptoms of depression, the cause is not always addressed.
The study was carried out by researchers from the University of Illinois and was funded by the VA Merit award.
This study has been reported accurately by the Mail Online. But while the website does point out that the study was in rats, it does not discuss the inherent limitations of animal studies.What kind of research was this?
This animal study in rats aimed to create a better understanding of the delay in the action of antidepressants and find a way to develop faster-acting treatments.
Depression is common worldwide and a leading cause of long-term disability. Many people who are treated with antidepressants do not respond to treatment.
There is a need for a better understanding of how these drugs work, particularly why they can take several weeks to see any effect.
Many people take their own lives during the first few weeks of their drug treatment. Accelerating the effects of antidepressants could potentially save many lives.
Animal studies are often used in the early stages of research to see how biological processes may work in humans.
However, we are not identical to animals, and findings would need to be followed up in humans to confirm that the same effect is observed.What did the research involve?
This was complex laboratory research using rat cells to observe the mechanisms of action of antidepressant medications, and the effect on cellular proteins and messenger molecules like serotonin (also known as a monoamine neurotransmitters).
Researchers used a particular type of rat brain tumour cell called C6 glioma cells, because they lack monoamine or serotonin transport proteins in their membranes.
This, while not identical, mimics the chemical make-up of the "depressed brain" in humans; a brain with low levels of serotonin.
Previous studies have shown antidepressant drugs relocate transport proteins called Gα to the lipid membranes.
This redistribution is in turn thought to affect levels of the signalling molecule cyclic adenosine monophosphate (cyclic AMP, or cAMP), which controls many metabolic processes.
Cells were soaked in various types of antidepressants in the laboratory. The accumulation of the medications was measured by UV absorbance and spectroscopy to identify the different substances within the cells.
The researchers aimed to look at the composition of cells to investigate their theory about the effect of antidepressants on Gα proteins and cAMP.What were the basic results?
The researchers believe the cause for the delayed action of antidepressants is partly because of their effect on redistributing Gα proteins to the lipid cell membranes.
They demonstrated that the entry of antidepressants into the cell doesn't rely on serotonin reuptake transport protein.
Gα proteins are gradually redistributed to the cell membranes, where it then activates cAMP signalling.
The extent of Gα protein redistribution was dependent on the dose or concentration of the antidepressant and the duration of exposure.
This gradual distribution and signalling effect may be responsible for the delayed mechanism of action of the drugs.How did the researchers interpret the results?
The researchers concluded that, "It appears that at least one action of antidepressants is to accumulate in lipid rafts and mediate the movement of [Gα proteins] out of lipid rafts. This may represent a novel biochemical hallmark for antidepressant action.
"Furthermore, identification of the antidepressant-sensitive molecular anchor for [Gα proteins] in lipid rafts may lead to the development of more targeted therapies for depression, including compounds that may have a much more rapid course of action."Conclusion
This experimental study in rat brain cells investigated the delay in the action of antidepressants. This research hopes to aid the development of faster-acting treatments in the future.
It is thought antidepressants work by increasing levels of neurotransmitters, such as serotonin, in the brain – chemicals that can improve mood and emotion.
The researchers' experiments in rats found antidepressants seem to lead to a gradual redistribution of Gα proteins to the lipid membrane of the brain cells, which in turn affects signalling processes.
However, this is a slow process that seems to depend on the dose of antidepressant and the duration of exposure.
The delay in antidepressant action is not fully understood. This research helps take us one step closer to understanding this, and hopefully from this developing faster-acting treatments.
But this was an early-stage experiment in rats. We don't know that this provides the whole answer, and findings would need to be confirmed in a human study.
While these findings may guide future drug research, it is far too early to assess how long they will take to come to fruition (or if at all).
While antidepressants can treat the symptoms of depression, the cause is not always addressed.
Cognitive or behavioural therapies are often considered to be a first-line option for depression, or combined with drug treatment to try to give the best response.
If you're concerned that your symptoms of depression are failing to respond to drug treatment, contact your GP or the doctor in charge of your care as soon as possible.
Links To The Headlines
Links To Science
Erb SJ, Schappi JM, Rasenick MM. Antidepressants Accumulate in Lipid Rafts Independent of Monoamine Transporters to Modulate Redistribution of the G protein, Gαs. The Journal of Biological Chemistry. Published online July 18 2016
"Menopause 'crushes your motivation to exercise'," the Mail Online reports. But before you bin your gym card, the study it reports on involved rats, not women.
The female rats were genetically engineered to have either a high or low exercise capacity.
Those who had their ovaries removed to model human menopause showed lower activity on a running wheel over the following 11 weeks compared with those who hadn't.
And surprisingly the rats that had prior high exercise capacity had no protection – in fact, their activity levels declined more than the rats who'd been less active to start with.
The reason seemed to be because lack of oestrogen alters dopamine activity in the brain's motivation and reward centre.
In simplistic terms, dopamine is often described as a "feel-good" chemical and has been linked to many addictive activities, such as gambling.
The findings may give a possible explanation for why some women going through the menopause may feel less motivated to exercise.
But humans aren't genetically engineered rats, and we don't know that our biological mechanisms work in exactly the same way.
Also, the rats were not given any type of hormone replacement therapy (HRT) to boost oestrogen levels, so these finding may not be applicable for women who choose to have HRT.
Physical activity is recommended at all stages of life, and many postmenopausal women enjoy very active lifestyles.
The best thing for people to do is to follow physical activity recommendations where possible, doing what feels comfortable for them.Where did the story come from?
The study was carried out by researchers from the University of Missouri and the University of Kansas Medical Center, and received funding from the US National Institutes of Health.
It was published in the peer-reviewed journal, Physiology and Behavior.
The Mail's headline boldly states that the findings directly relate to menopausal women – only hidden well down in the article does it say that it involved rats.What kind of research was this?
This animal research in genetically engineered rats aimed to see whether those bred to have high exercise capacity are better protected from losing interest in physical activity after they have their ovaries removed, compared with rats bred to have low exercise capacity.
As the researchers say, most people fail to meet physical activity recommendations. Rats bred to have high or low running capacity have also been shown to have different behaviour on a voluntary running wheel.
The researchers think this may be because of differences in dopamine pathways in a brain region called the nucleus accumbens, which control self-motivated activity and reward.
Oestrogen has been shown to stimulate dopamine receptors and maintain activity in rats.
A loss of oestrogen from the rat's ovaries being removed – modelling human menopause – may be expected to reduce activity. This is what the researchers aimed to examine.
Animal studies can give a good insight into biological mechanisms that may be similar in humans, but we are not genetically engineered rats.What did the research involve?
The research involved two types of rats – those bred to have either a high or low exercise capacity.
There were 40 female rats in each group, who were then randomised to either have their ovaries removed or a sham operation.
After one week of recovery they were given access to a voluntary running wheel. Their wheel running was monitored weekly for 11 weeks.
The rats also had other assessments of body composition and blood glucose control. Their brain tissue was examined after death, paying close attention to dopamine activity in the nucleus accumbens.What were the basic results?
The high exercise capacity rats ran more on the wheel compared with the low capacity rats.
Ovary removal significantly reduced activity in both groups compared with rats who received the sham procedure.
Strangely, while the high capacity rats who had their ovaries removed demonstrated a weekly reduction in the distance they ran on the wheel over the 11 weeks, the low capacity rats with their ovaries removed actually increased the amount they ran each week.
This meant that by the end of the 11 weeks there was no difference in running between the high and low capacity rats who had their ovaries removed.
Brain examination showed that high capacity rats had greater dopamine activity than the low capacity rats.
Removing the ovaries was associated with increased dopamine blocking in the high capacity rats, but was linked to reduced dopamine blocking in the low capacity rats.How did the researchers interpret the results?
The researchers concluded that the dopamine system in the brain's nucleus accumbens plays an important role in motivation to run in female rats.
High capacity rats run significantly more than low capacity rats, which is the result of a higher ratio of excitatory to inhibitory dopamine receptors.
The researchers say that despite greater inherent motivation to run, high capacity rats are not protected against the effect that ovary removal has upon dopamine activity.
It reduces the ratio of excitatory to inhibitory dopamine activity, "for which intrinsic fitness does not confer protection".Conclusion
This research uses an animal model of human menopause – surgically removing the ovaries – to see what effect this would have on rats bred to have either high or low exercise capacity.
As oestrogen has been shown to have an effect on dopamine activity in the brain's motivation centre, the researchers expected that ovary removal would have an effect on the rats' activity.
However, what was unexpected was that having prior high exercise capacity seemed to give no protection – these rats seemed to decrease their activity much more than rats that had low activity to start with.
These findings could be stretched to explain a possible reason why women who've been through natural or induced menopause (such as having their ovaries removed) may feel less motivated to exercise, particularly if they were very active previously – because of changes in dopamine activity in the brain.
However, humans are obviously not genetically engineered rats running on a wheel. Animal studies can give a good insight into biological mechanisms that may be similar in humans, but we don't know that things work exactly the same.
We also don't know whether these are permanent changes that would persist in the long term, or whether they're only short-term changes around the time of menopause.
Overall, the findings are of interest, but they do not have any preventative or therapeutic implications.
Physical activity is recommended at all stages of life, and many postmenopausal women enjoy very active lifestyles.
Exercise can be especially important at this time, as it can help boost bone strength, which can weaken during the menopause.
The best thing for people to do is follow physical activity recommendations where possible, doing what feels comfortable for them.
For all adults, including people over 65 who are generally fit and healthy, this is at least 150 minutes of moderate aerobic activity every week (such as cycling or walking) combined with strength exercises that work all muscle groups on two or more days a week.
Links To The Headlines
Links To Science
Park YM, Kanaley JA, Padilla J, et al. Effects of intrinsic aerobic capacity and ovariectomy on voluntary wheel running and nucleus accumbens dopamine receptor gene expression. Physiology & Behavior. Published online June 11 2016