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Updated: 13 hours 40 min ago

Can exercise offset some of the harms of regular drinking?

Fri, 09/08/2017 - 17:28

"Adults who booze regularly but exercise for five hours a week are no more likely to die than teetotallers," the Mail Online reports.

A study suggests exercise may compensate for some, but certainly not all, of the harms associated with excessive alcohol consumption. This latest study looked at deaths from cancer and cardiovascular disease, as well as premature death in general (usually judged to be dying before the age of 75).

Researchers looked at around 10 years' worth of national survey data from UK adults aged over 40. Unsurprisingly, they found links between all-cause and cancer mortality in inactive people. But they also found increasing levels of physical activity generally removed the association with drinking habits. In fact, occasional drinking was associated with a significant reduction in all-cause mortality for the most active of people.

Although the study had strengths in its large sample size and regular follow-up, we can't be sure that any links observed were solely down to the interaction between alcohol and exercise. For example, people who are physically active may also avoid smoking and consume healthy diets. It is difficult to completely control for such influences when analysing data like this.

While regular exercise may mitigate against some of the harms associated with excessive alcohol consumption it certainly won't make you immune. Many world-class sportspeople, such as George Best and Paul Gascoigne, have had both their careers and lives blighted by drinking.

 

Where did the story come from?

The UK-based study was carried out by an international collaboration of researchers from Canada, Australia, Norway and the UK. The health surveys on which the study was based were commissioned by the Department of Health, UK. Individual study authors also reported receiving funding from the National Health and Medical Research Council and University of Sydney. 

The study was published in the peer-reviewed British Journal of Sports Medicine. 

The media coverage around this topic was generally overly optimistic, highlighting that by exercising, individuals can completely undo the harm caused by excessive alcohol consumption, which is untrue.

In particular, the Mail Online claimed "Adults who booze regularly but exercise for five hours a week are no more likely to die than teetotallers" which could send out the wrong message to the public.

 

What kind of research was this?

This cohort study analysed data from British population-based surveys: Health Survey for England (HSE) and the Scottish Health Survey (SHS) to investigate whether physical activity is able to moderate the risk between alcohol consumption and mortality from cancer and cardiovascular diseases.

Cohort studies like this are useful for assessing suspected links between an exposure and outcome. However, there are potentially other factors that have a role to play in such associations and therefore the study design doesn't allow for confirmation of cause and effect.

 

What did the research involve?

The researchers collected data on 36,370 men and women aged 40 or above from Health Survey for England (1994; 1998; 1999; 2003; 2004; and 2006) and the Scottish Health Survey (1998 and 2003). Among other things, the participants were asked about their current alcohol consumption and physical activity.

Alcohol intake was defined by six categories (UK units/week):

  • never drink (lifetime abstainers)
  • ex-drinkers
  • occasional drinkers (haven't drank anything in past seven days)
  • within (previous) guidelines: <14 units (women) and <21 units (men)
  • hazardous: 14-15 units (women) and 21-19 units (men)
  • harmful: >35 (women) and >49 (men)

Frequency and type of physical activity in the past four weeks was questioned and converted into metabolic equivalent task-hour (MET-hours, which are an estimate of metabolic activity) per week according to national recommendations:

  • inactive (≤7 MET-hours)
  • lower level of active (>7.5 MET-hours)
  • higher level of active (>15 MET-hours)

The surveys were linked to the NHS Central Register for mortality data and the participants were followed up until 2009 (HSE) and 2011 (SHS). There were 5,735 recorded deaths; deaths from cancer and cardiovascular disease were of most interest for this study.

The data was analysed for associations between alcohol consumption and the risk of death from all-causes, cancer and cardiovascular disease. The results were then analysed according to levels of physical activity.

Potential confounders (such as sex, body mass index and smoking status) were controlled for.

 

What were the basic results?

Overall, the study found a direct link between all levels of alcohol consumption and risk of cancer mortality. It also found that increasing levels of physical activity reduced this association with cancer mortality, and also reduced the link with death from any cause.

  • In individuals who reported inactive levels of physical activity (≤7 MET-hours), there was a direct association between alcohol consumption and all-cause mortality.
  • However, in individuals who met the highest level of physical activity recommendations a protective effect of occasional drinking on all-cause mortality was observed (hazard ratio: 0.68; 95% confidence interval (CI): 0.46 to 0.99). It should be noted that this result just skimmed the cut-off point for statistical significance.
  • In this high activity group, there was no link between all-cause mortality and alcohol consumption within guidelines, or even hazardous amounts, but the risk was still increased for those drinking harmful amounts.
  • The risk of death from cancer increased with the amount of alcohol consumed in inactive participants, ranging from a 47% increased risk for those drinking within guidelines to 87% increased risk for those with harmful drinking.
  • In people with higher activity levels (above 7.5 MET hours) there was no significant link between any amount of alcohol consumption and cancer mortality.
  • No association was found between alcohol consumption and mortality from cardiovascular disease, although a protective effect was observed in individuals who reported the lower and higher levels of physical activity (>7.5 MET-hours) and (>15 MET-hours) respectively.

 

How did the researchers interpret the results?

The researchers concluded "we found evidence of a dose–response association between alcohol intake and cancer mortality in inactive participants but not in physically active participants. [Physical activity] slightly attenuates the risk of all-cause mortality up to a hazardous level of drinking."

 

Conclusion

This study aimed to explore whether physical activity is able to moderate the risk between alcohol consumption and mortality from cancer and cardiovascular diseases. It found that increasing levels of physical activity reduced the association for death from both all-causes and cancer.

This study has strengths in its large sample size, comprehensive assessments and long duration of follow-up. The findings are interesting, but there a few points to bear in mind:

  • As the authors mention, cohort studies such as this are unable to confirm cause and effect. Though the researchers have tried to account for various potential health and lifestyle confounding variables, there is the possibility that others are still influencing the results. A notable one is dietary habits which weren't assessed. Also, for example, the former drinkers may have quit due to other health issues which may have introduced bias.
  • The study was unable to look at binge drinking levels of alcohol consumption which would have likely had important health implications.
  • Additionally, there is always the possibility with self-reported surveys that the participants either under or over-reported their drinking habits which can increase the chance of misclassification bias.
  • Though having a large sample size, fewer people reported harmful drinking levels, so links within this category may be less reliable.
  • The study has only looked at the link between alcohol and actually dying from cancer or cardiovascular disease. Links may be different if they looked at associations between alcohol and just being diagnosed with cancer or heart disease, for example.
  • The study is also only representative of adults over the age of 40.

Overall, maintaining a healthy lifestyle seems to be the best bet for reducing the risk of any chronic disease, be it through physical activity, balanced diet or reasonable alcohol consumption.

Current alcohol recommendations for both men and women are to drink no more than 14 units per week.  

Links To The Headlines

How exercise undoes the harm from drinking: Adults who booze regularly but exercise for five hours a week are no more likely to die than teetotallers. Mail Online, September 8 2016

Two hours a week of exercise could offset the dangers of alcohol. The Daily Telegraph, September 8 2016

Exercise can cut risk from alcohol-related diseases, study suggests. The Guardian, September 8 2016

Links To Science

Perreault K, Bauman A, Johnson N, et al. Does physical activity moderate the association between alcohol drinking and all-cause, cancer and cardiovascular diseases mortality? A pooled analysis of eight British population cohorts. British Journal of Sports Medicine. Published online August 31 2016

People who regularly groom their pubic hair at risk of injuries

Thu, 08/17/2017 - 18:30

"A quarter of Americans are injured and hospitalized by tidying up 'down there'," the Mail Online reports.

The headline is prompted by a survey which asked 7,570 adults about pubic hair removal and "grooming" (such as waxing). The researchers found that removing all pubic hair, and frequent hair removal, were most likely to cause injuries.

Pubic hair removal has become more common in recent years. This could be due to the mistaken assumption that grooming is more hygienic (as we discussed in 2016). Some commentators have also cited the influence of pornography, where shaved genitals are the norm.

The researchers found 66.5% of men and 85.3% of women who responded to their survey had removed or groomed pubic hair at some point in their lives. However, it's not as dangerous as the Mail Online headline suggests – while 25.6% of people reported at least one injury, these were almost all minor and only 1.4% reported injury that required medical attention.

Cuts, burns, rashes and infections were the main problems. Waxing seemed to cause fewer injuries than shaving, although researchers say more study is needed before it can be recommended as a safer option.

Previous research has shown that removal of pubic hair can also make sexually transmitted infections (STIs) such as HPV more likely.

The most effective method of reducing your risk of catching an STI is to always used a condom during sex, including oral and anal sex.

 

Where did the story come from?

The study was carried out by researchers from the University of California, the University of Texas Dell Medical School and the Washington University School of Medicine, all in the US. It was funded by the Alafi Foundation, the Hellman Foundation and the National Institute of Diabetes and Digestive and Kidney Diseases.

It was published in the peer-reviewed medical journal JAMA Dermatology.

The Guardian carried a balanced and accurate report of the study. In contrast, the Mail Online's reporting was muddled, misleading and sensationalised. For example, the website states: "A quarter of groomers have suffered severe injuries," although the injuries were mostly minor.

The Mail also inaccurately reported that "more than a third of people surveyed by government health researchers" said they'd had five or more injuries – although this figure applies to only one third of the 25% of people injured, not one third of people questioned. The report also includes findings from other studies as if they were part of the new study which could further mislead the reader. 

 

What kind of research was this?

This was a cross sectional study, using a web-based survey targeted at US adults aged 18 to 65. The researchers contacted more than 10,000 adults in a "nationally representative" sample.

This type of study can give a snapshot view of what people are prepared to say in a survey about their grooming habits. However, it can't guarantee people answer truthfully.

Also, this methodology leaves any results open to accusations of selection bias. People who take the time to complete the survey may not be representative of the general public.

 

What did the research involve?

Researchers randomly recruited people to take the survey through sampling of the US postal service database. An email request was sent out in January 2014 asking people to take part in the online survey.

The survey asked questions about people's grooming habits, experience, injuries and infections.

To ensure people weren't excluded because of lack of internet or computer access, those without access were provided with internet facilities to complete the questionnaire.

Participants also received a small points-based incentive equivalent to one dollar.

The results were analysed to find out the extent and nature of the problem, and to identify factors that seemed to increase the risk of injury.

 

What were the basic results?

Almost half of the people contacted declined to take part in the survey. Of the 52.5% of people (7,570) who did take part:

  • 66.5% of men said they had groomed their pubic hair, and 23.7% said they'd been injured while doing it
  • 85.3% of women had groomed their public hair and 27.1% had been injured

The most common problems were:

  • cuts (61.2%)
  • burns (23.0%)
  • rash (12.2%)
  • infection (9.3%)

This may reflect the types of hair removal methods used. Shaving with a non-electric razor was the most common method (47.5%) followed by electric razor (26.9%), scissors (18.4%) and waxing (2.6%).

For women, those who reported waxing as their main method of hair removal were less likely to have repeated frequent injuries (adjusted odds ratio (AOR) 0.11, 95% confidence interval [CI] 0.03 to 0.43). For men (who were less likely to wax) the type of hair removal method made no difference to injury rate.

Women and men who removed all pubic hair regularly (more than 10 times per year) were more likely to report having an injury (women: AOR 2.21, 95% CI 1.53 to 3.19; men: AOR 1.97, 95% CI 1.28 to 3.01).

The position adopted while grooming made some difference to the severity of injury. People were more likely to get an injury that needed medical attention if they carried out hair removal lying on their back (perhaps because they could not see what they were doing) or if other people were carrying out the hair removal.

 

How did the researchers interpret the results?

The researchers said their research showed that "pubic hair grooming is a widespread practice" and so "injury prevention efforts are necessary". They said their study "may contribute to the development of clinical guidelines or recommendations for safe pubic hair removal."

 

Conclusion

Pubic hair removal is now common practice, and this study suggests it is not without risk. It seems sensible to find out more about how it can be done safely, with minimal risk of injury.

However, while the study provides useful information about peoples' experiences of pubic hair removal and injury (at least in the US), it doesn't tell us which is the safest method.

Although waxing was linked to fewer repeated injuries among women, previous studies suggest it can be harmful if done incorrectly, leading to severe injury or infection.

Similarly, although frequent removal of all pubic hair is linked to higher risk of injury, we don't know why this is. It may simply be that doing anything regularly means you have more opportunities to make a mistake.

The research has some limitations. It's notable that almost half of people contacted didn't take the survey. It may be that the people who refused to do the survey were less likely to carry out pubic hair grooming or removal, or are more likely to be embarrassed at the thought of answering questions about it.

Because the research relies on people's own reporting of their experience, we don't know how accurate it is. People may be too embarrassed to give truthful answers, may forget minor injuries, or people who suffer major injuries may be more likely to respond to the survey. All of these things could skew the results.

While people may choose to remove their pubic hair for cosmetic reasons, there are no medical benefits to the practice, and it could increase your risk of contracting a sexually transmitted infection, as we reported on last year.

Links To The Headlines

The dangers of pubic hair grooming: A QUARTER of Americans are injured and hospitalized by tidying up 'down there' - and this study reveals the nation's stupidest techniques. Mail Online, August 16 2017

Wax on, wax ouch: pubic grooming has a high injury rate, survey reveals. The Guardian, August 16 2017

Links To Science

Truesdale MD, Osterberg EC, Gaither TW. Prevalence of Pubic Hair Grooming–Related Injuries and Identification of High-Risk Individuals in the United States. JAMA Dermatology. Published online August 16 2017

Kitchen sponges may be a 'bacteria hotspot' – but no need to worry

Thu, 08/03/2017 - 13:30

"Study finds just a sugar-cube sized piece of kitchen sponge can contain 54 BILLION bacterial cells," the Mail Online reports. A German study sampled 14 different kitchen sponges and found they contained far more bacteria than expected.

Genetic analysis revealed the used sponges contained billions of bacteria, from 362 species-like groups called "operational taxonomic units" (OTUs).

However, it's not clear that any would be harmful in the context of someone's typical exposure to a kitchen sponge, despite 5 of the 10 most common OTUs found being bacteria from "risk group 2" (RG2) – a classification including bacteria that may cause disease in certain circumstances.

For example, researchers found high levels of the Acinetobacter strain of bacteria. This can cause potentially serious infections – but only if it penetrates deep inside the body, or infects traumatic wounds or burns.

People associate bacteria with germs. But we are all covered in bacteria, inside and out, and so are our homes. Most are either harmless or actually play a useful role in biological processes, such as digestion. Only a few cause diseases, so the fact kitchen sponges harbour bacteria is not as alarming as it sounds.

The researchers found that methods to clean sponges, such as heating them in microwaves to kill bacteria, don't work particularly well. They suggest replacing sponges weekly rather than cleaning and re-using them.

Where did the story come from?

The study was carried out by researchers from Justus-Liebig University Giessen, Furtwangen University and the German Research Centre for Environmental Health, all in Germany. It was funded by the Institute of Applied Research (IAF) of Furtwangen University and published in the peer-reviewed journal Nature Scientific Reports on an open-access basis, so it can be read online free of charge.

The Mail Online carried a reasonably accurate report of the research. However, it made much of the fact that some of the bacteria identified came from RG2, a class that includes "bacteria that cause typhoid fever, the plague, cholera and food poisoning". While this is correct, the researchers did not find any of the actual bacteria that cause these conditions in the sponges tested.

What kind of research was this?

This was a genetic analysis of a small sample of kitchen sponges to assess the number, variety and density of bacteria living on and within them.

This type of study can investigate the amount and type of bacteria present in the sponges. However, it can't tell us where the bacteria came from or how they may have affected the health of the people using the sponges.

What did the research involve?

Researchers collected 14 used kitchen sponges from houses in a German town, along with information about how regularly sponges were changed and whether they were specially cleaned to remove bacteria. The type, number and density of bacteria within the sponges were assessed using the latest genome sequencing techniques and a microscopy visualisation technique.

Most previous studies of bacteria in kitchens and kitchen accessories – such as dishcloths and sponges – used bacterial culturing, which can only detect species that can be grown on culture plates in the laboratory. This study used a genetic sequencing technique, called 454-pyrosequencing, of 16S RNA genes to find a much larger range of bacteria, including those that are difficult or impossible to culture in the laboratory.

Laser scanning microscopy was used on fixed samples of sponge to visualise the numbers and density of bacteria.

The researchers grouped the bacteria into OTUs, which was a way of classifying closely related bacteria so they could then divide them into types that might cause infection.

They also checked to see if cleaning the sponges using special processes, such as microwaving them, affected the number or types of bacteria found.

What were the basic results?

The researchers found billions of bacteria on the sponges' surfaces and the walls of their interior spaces. Among these, gene sequencing identified 362 OTUs, the majority of which were related to the gammaproteobacteria phylum (a group of classes that share distinctive characteristics).

The 10 most frequently found OTUs were responsible for almost 70% of all the gene sequences found on the sponges, and 5 of these 10 fell into the "German Technical Rule for Biological Agents Risk Group 2", suggesting they may have the potential to cause disease in humans.

The researchers didn't find any signs of salmonella, proteus or campylobacter, which are known to cause food poisoning and would be concerning to see in a kitchen or similar environment.

Imaging showed that most of the bacteria were still growing at the time of analysis. The highest density of bacteria recorded was 54 billion bacterial cells in a 1cm cube of sponge.

How did the researchers interpret the results?

The researchers concluded that "kitchen sponges harbour a higher bacterial diversity than previously thought" but "human pathogens [disease-causing bacteria] might represent just a minority" of the bacteria found.

They added: "Sponge sanitation methods appear not sufficient to effectively reduce the bacterial load and might even increase the shares of RG2-related bacteria."

Instead of attempting to clean sponges, they suggest "a regular (and easily affordable) replacement of kitchen sponges, for example on a weekly basis".

Conclusion

There's no need to panic about the results of this study. Bacteria are everywhere, so it's no surprise to find them growing in kitchens. The researchers say sponges, being porous and usually damp, represent ideal conditions for bacteria to grow.

The study found that one of the most dominant types of bacteria came from the Moraxella family. These bacteria are often found on human skin, so it's likely they got onto the sponges from people's hands. Moraxella are also linked to the unpleasant smell sometimes found after laundry has taken longer to dry, so they seem to be common in the household environment. 

The study has a few limitations. As only 14 sponges from one area of Germany were tested, we don't know if the results would apply to households in other parts of the world.

The researchers say the relation of the ONU gene sequences to RG2 species provides "only a weak indicator for the pathogenic potential of the identified bacteria" and that they are "not aware of any case in which an infection from these bacteria was explicitly reported from a domestic environment". The technology is not yet precise enough to show that any specific bacteria found growing in sponges causes disease.

However, we do know poor kitchen hygiene can lead to infections, especially when preparing uncooked food, such as salad or raw chicken. Bacteria-laden sponges, if used to wipe down surfaces, could spread pathogenic bacteria around and make infection more likely. You might want to consider simply replacing your sponge regularly, instead of rinsing it in hot water or zapping it in the microwave.

Read more advice about Food safety and home hygiene.

Links To The Headlines

You'll never do the dishes in the same way again: Study finds just a sugar-cube sized piece of kitchen sponge can contain 54 BILLION bacterial cells. Mail Online, August 2 2017

Links To Science

Cardinale M, Kaiser D, Lueders T, et al. Microbiome analysis and confocal microscopy of used kitchen sponges reveal massive colonization by Acinetobacter, Moraxella and Chryseobacterium species. Scientific Reports. Published online July 19 2017

Western sperm counts 'halved' in last 40 years

Wed, 07/26/2017 - 18:30

"Sperm counts among Western men have halved in last 40 years," The Guardian reports. A major review of research carried out since 1973 found an estimated 50-60% drop in sperm count in developed nations.

Researchers looked for studies that reported measures of either total sperm count or sperm concentration in men not known to have fertility problems.

They analysed the findings of these studies and considered trends over time to see if there had been any changes in recent decades.

They concluded that total sperm count and sperm concentration had decreased over time in Western countries, but this trend was not as strong or didn't exist in other parts of the world, such as Africa, Asia and South America.

Both the researchers and the media have a number of theories as to why this might be the case, ranging from exposure to chemicals and pesticides to The Independent's suggestion that modern life was to blame.

It's not clear why. Both the researchers and the media offered a number of suggestions. But until further research is carried out, we just don't know whether these speculations have any merit.

Talk of human extinction in the media is premature. Although the study did report a dramatic-sounding decline in average sperm count from 92.8 million/ml to 66.4 million/ml, this is still well within the range needed to conceive.

Men can help protect their sperm by avoiding smoking and not drinking too much alcohol.

Where did the story come from?

The study was carried out by researchers from the Hebrew University Center of Excellence in Agriculture and Environmental Health and the Ben-Gurion University of the Negev, both in Israel, as well as the Icahn School of Medicine in the US, the University of Copenhagen in Denmark, the Federal University of Parana in Brazil, and the University of Murcia School of Medicine and Biomedical Research Institute of Murcia in Spain.

It was published in the peer-reviewed journal Human Reproduction Update on an open access basis, so it's free to read online.

The study was funded by the Environment and Health Fund, Israel, with additional support given to individual researchers from the American Healthcare Professionals and Friends for Medicine in Israel, the Israel Medical Association, the Research Fund of Rigshospitalet, the Brazilian National Council for Scientific and Technological Development, and the Mount Sinai Transdisciplinary Centre on Early Environmental Exposures.

While the press coverage did accurately report the trends, many headlines were misleading as they focused on the researchers' comments, rather than the study's findings. The actual research didn't look into the causes of any declines in sperm count.

What kind of research was this?

This systematic review and meta-analysis aimed to find existing research that had looked directly at human sperm counts in different populations and explore whether any changes had occurred over time.

This study design has some benefits for exploring whether sperm count is declining, as it allowed the authors to look at findings from a far greater number of people and populations than would usually be possible in a single study.

But not all of the studies included were the same quality, and the researchers weren't able to look at data from every man involved in those studies.

What did the research involve?

The researchers searched databases of medical research in a systematic way and found 185 studies that had looked directly at human sperm count in men either confirmed to be fertile or who had unknown fertility status (unselected men).   

The researchers analysed data on both sperm concentration and total sperm count collected between 1973 and 2011.

The authors also analysed data on a range of confounding factors that could have influenced sperm count, such as:

  • age
  • how long it had been since a man last ejaculated before providing a sperm sample (abstinence time)
  • whether semen collection and counting methods were reported
  • number of samples provided per man

If data was missing on an important factor, the authors found ways of replacing it with an estimate.

They carried out a meta-regression analysis, where the results of the different studies were combined and the influence of other factors, such as the men's ages, was taken into account. This was an appropriate method of analysis for this type of research. 

If data was missing on an important factor, researchers found ways of replacing it with an estimate.  

What were the basic results?

When the researchers combined the basic results of all the studies without taking into account other influencing factors, they found that from 1973-2011 there was on average a 0.75% decrease in sperm concentration every year (95% confidence interval [CI] 0.73% to 0.77%) with an overall drop of 28.5% over the period. The average sperm count had dropped from 92.8 million/ml to 66.4 million/ml.

When they looked at total sperm count, which takes into account the volume of semen, the yearly decrease was also 0.75% (95% CI 0.72% to 0.78%) with an overall drop of 28.5%. This meant a drop from 296 million to 212 million.

When other factors were taken into account in the analysis (for example, age, region, abstinence time, sperm collection methods), the results for each group were as follows:

  • unselected Western men had a 1.4% decrease in sperm concentration per year, with an overall drop of 52.4% from 99 million/ml in 1973 to 47 million/ml in 2011
  • unselected Western men had a decrease in total sperm count of 1.6% per year and 59.3% overall, reducing from 337.5 million in 1973 to 137.5 million in 2011
  • fertile Western men had a 0.8% decrease in sperm concentration per year, reducing from 84 million/ml to 62 million/ml, but there was no significant difference for total sperm count

There were no significant changes in sperm concentration or total sperm count for unselected and fertile men from other regions. 

How did the researchers interpret the results?

The researchers concluded there had been a "significant overall decline" in both sperm concentration and total sperm count in Western countries over the study period, particularly among men who were unselected.

They noted there was no "levelling off" of the trend, which would suggest there may be further declines in the future.

The researchers have expressed concern at their findings, making calls for research into the causes of these trends to be prioritised.

Conclusion

This research presented a useful summary of existing studies in the area of human sperm count, and presented some interesting findings relating to trends over time.

But this study does have some limitations:

  • The research was based on a wide range of populations who, in some cases, may only have been assessed once. Following a fixed population over time in a cohort study might have had different findings.
  • Research that wasn't published in English wasn't included, and there also aren't many studies published before 1985 from countries in the other category. This might have an effect on whether the estimates from this population are correct, as studies from those countries might be less likely to be published in English. Having fewer studies to draw upon may be why there are no significant trends in this group. 
  • The study looked at sperm count and concentration, not the quality of the sperm itself, because there was limited reporting of this information in older studies. Likelihood of conception depends not only on the amount of sperm but also its quality, so it would be useful to have this information to be able to make predictions about the impact of these findings on fertility rates.
  • The authors didn't report any kind of formal quality assessment of the studies they included in their analysis.

Although this research suggests there may be a decline in sperm count in Western countries in recent years, it doesn't offer any explanations.

It also doesn't tell us anything about the fertility of individuals, as the research was based on averages across populations.

The researchers have called for the scientific community to investigate possible reasons for the reported drop, which would seem like a good idea. 

Links To The Headlines

Sperm counts among western men have halved in last 40 years – study. The Guardian, July 25 2017

Huge drop in sperm count could lead to human extinction: Study reveals 60% drop in fertility since 1970 – driven by the unhealthy Western lifestyle. Mail Online, July 25 2017

Sperm count drop 'could make humans extinct'. BBC News, July 25 2017

Sperm counts in the West plunge by 60% in 40 years as 'modern life' damages men's health. The Independent, July 25 2017

Links To Science

Levine H, Jørgensen N, Martino-Andrade A, et al. Temporal trends in sperm count: a systematic review and meta-regression analysis. Human Reproductive Update. Published online July 25 2017

'Buying time' and not just things may increase life satisfaction

Tue, 07/25/2017 - 18:30

"Using money to free-up time is linked to increased happiness," BBC News reports. Researchers surveyed people from a number of developed countries and found those who reported using money to free up time, such as hiring a cleaner, tended to report higher life satisfaction.

Researchers surveyed more than 6,000 participants from the US, Canada, Denmark and The Netherlands, including around 800 Dutch millionaires, about "buying time" – which was defined as paying people to do chores that participants personally found unenjoyable. Researchers found that, regardless of income, people who bought time reported better life satisfaction.

A further small experiment found that spending money on time-saving purchases rather than material goods such as wine and clothes was associated with increased happiness and positive feelings and reduced feelings of "time stress".

However, due to the complex web of factors that affect our wellbeing, it is difficult to say that this study proves that "buying time" makes you more satisfied with your life.

Prioritising time over money and material goods may well be one route to happiness, but it may not work for everyone.

Of course not everyone can afford to hire a cleaner (or in the case of a Dutch millionaire, a butler). However there are techniques you can use that may help you manage your time more effectively.

Read more advice about time management.

 

Where did the story come from?

The study was carried out by researchers from Harvard Business School in the US, University of British Columbia in Canada, and Maastricht University and Vrije Universiteit Amsterdam, both in The Netherlands.

The study was funded by Public Scholars Initiative at the University of British Columbia, the Social Sciences and Humanities Research Council of Canada, the Society for Personality and Social Psychology Heritage Foundation, and the Society for Personality and Social Psychology Q&pAy Initiative.

The study was published in the peer-reviewed medical journal PNAS on an open-access basis, meaning it is freely available online.

The UK media's reporting of the study's findings wasn't accurate, as it failed to point out that the study is not able to prove cause and effect. There could have been multiple other reasons why some people reported greater life satisfaction.

For example, the headline in the print edition of the Daily Mail: "The secret behind true happiness? Hire a cleaner" is not representative of the findings of the study.

 

What kind of research was this?

This research involved multiple cross-sectional studies using questionnaires. There was also a small experimental study, randomising people to spend $40 (around £30 at time of writing) on material goods one weekend and time-saving purchases another weekend and then asking them about their level of stress and happiness.

Using a questionnaire is a good way of including a lot of people and in this case allowed researchers to easily look at participants' answers from four countries. However, this can only tell us what their levels of perceived happiness and satisfaction are in relation to the "ladder of life rung" they are on at one time point. It is likely other factors such as job, relationships and health status would have more of an effect on these perceptions, but none of these were taken into account.

The additional experimental component added little weight to their argument as again they did not take into account any other potential confounding factors.

 

What did the research involve?

Researchers carried out questionnaires with 6,271 participants from the US, Canada, The Netherlands (including a sample of 800 millionaires) and Denmark to investigate the effect of buying time on life satisfaction. They also conducted an experimental study to test the results of the questionnaire.

The researchers firstly carried out surveys involving questions about how much money, if any, people spend every month to free up their time by paying someone else to complete daily tasks they do not find enjoyable. They were also asked about their satisfaction with life through two questions: "Taking all things together, how happy would you say you are?", and where they currently stand on a ladder spanning from the worst possible to best possible life imaginable.

Participants also answered questions on potentially confounding factors, including:

  • annual household income
  • number of hours worked each week
  • age
  • marital status
  • number of children living at home
  • the amount spent on groceries, material and experiential purchases (buying an "experience" such as a night out at the theatre), to account for the fact that decisions to spend money on time-saving purchases might be a reflection of income

In the Canadian and Dutch surveys, participants also reported a measure of "time stress". This includes stating how much they agreed with statements such as "I feel pressed for time today", "Compared to yesterday, I feel more stressed out about my time", and "Time is my scarcest resource".

The researchers then carried out an experiment on 60 Canadian working adults. They were asked to spend the equivalent of £30 on two consecutive weekends; on one weekend they were randomly assigned to purchase something that would save them time and on the other weekend, a material purchase.

After making each purchase, participants received a phone call at 5pm to report their feelings of positive or negative mood and time stress on that particular day.

 

What were the basic results?

Across samples from all included countries, 28.2% of participants spent money to buy themselves time each month with a mean spend of $147.95 US dollars per month in those who "bought time".

When controlling for variables, those who spent money in this way reported slightly better life satisfaction than those who did not. This effect was not altered by wealth or income.

The researchers then considered a broader definition of time-saving purchases, to cover any way a respondent might spend money to provide more free time.

Of a sample of 1,802 US working adults, 50% reported spending money in this way, with most buying their way out of cooking, shopping and household maintenance.

Again, when controlling for variables, those who spent money in this way reported slightly better life satisfaction, when controlling for the amount spent on groceries, material goods and experiences.

In the experiment phase of the research:

  • Participants reported a greater end of the day positive mood on a 12-item scale after making a time-saving purchase versus material purchase.
  • Participants reported a lower end of the day negative mood on a 12-item scale after making a time-saving purchase versus material purchase.
  • Participants reported lower feelings of time stress after making a time-saving purchase versus material purchase.

 

How did the researchers interpret the results?

The researchers concluded that "across several distinct samples, including adults from Canada, the United States, Denmark, The Netherlands, and a large sample of Dutch millionaires, buying time was linked to greater life satisfaction. These results held controlling for a wide range of demographics, as well as for the amount that respondents spent on groceries and material and experiential purchases each month. These results were not moderated by income, suggesting that people from various socioeconomic backgrounds benefit from making time-saving purchases."

 

Conclusion

This large multi-country study on adults of various incomes found that buying time was linked to greater life satisfaction, even when considering a wide range of demographics and spend on other items each month. It also seemed to show that people were in a better mood when buying something that saved them time versus buying something material.

These results are interesting in the busy, time-pressured culture many of us face today. The researchers suggest using money to buy time may reduce feelings of time pressure and buffer against negative effects of time pressure on life satisfaction.

While this may be the case, before you start giving up all household chores, you might want to consider some limitations to the research:

  • These were mainly cross-sectional studies with responses given at one time point. This means they cannot show that paying people to do tasks for you improves life satisfaction or happiness. Both will be dependent on a variety of factors that were not taken into account, such as employment, work/life balance, social situation, family life, personality and health status.
  • For the small experimental study, the researchers did not look at what other activities or events were occurring on those two particular weekends that may have affected mood and stress levels rather than what they had purchased. In addition, the participants knew what the money was being spent on, which could have biased the results.
  • Participants self-reported their activities. It might be that not all wanted to admit that they pay other people for housework.
  • Participants also self-reported life satisfaction. People might want to seem like they are happier with their life to justify paying someone to do housework, which might not necessarily be the case.
  • As the results showed, the question around paying money to free up time is subjective – some people might include paying for a ready-made lunch in this category whereas others might just think of paying other people to do housework as fitting into this definition.
  • The median age in the millionaires category was 68 compared with 30 in one of the US samples. This variation in age, as well as other factors such as number of children in the household, might mean people have different amounts of time to spend doing household chores so might be more or less stressed at the prospect of doing such activities.

If you are feeling "time stressed" there are time management techniques that can help as well as ways to help relieve feelings of stress.

Links To The Headlines

Time, not material goods, 'raises happiness'. BBC News, July 25 2017

Money CAN buy you happiness, as long as you spend it on time-saving luxuries: Forget trying to ‘do it all’ and spend cash on a cleaner or cook as it will give you greater life satisfaction. Mail Online, July 24 2017

Money can buy you happiness, claim researchers. The Independent, July 24 2017

Links To Science

Whillans AV, Dunn EW, Smeets P, et al. Buying time promotes happiness. PNAS. Published online June 24 2017

Snoring link to Alzheimer’s disease unproven

Mon, 07/24/2017 - 18:30

"Snoring linked to Alzheimer's," the Mail Online reports. A US study reported an association between sleep-disorder breathing and Alzheimer's disease in later life. But no definitive link between the two has been proven.

Sleep-disordered breathing is a general term to describe pauses in breathing during sleep that restrict oxygen supply to the body. At the most severe end of the spectrum is obstructive sleep apnoea, which can itself range in severity.

In this latest study, researchers looked at data regarding sleep in 1,750 middle aged and older adults. They then looked at whether problems with sleep breathing were associated with their performance in cognitive testing.

Researchers in the current study found a link between certain measures of sleep-disorder breathing and worse attention, short term memory and information processing speed. However, there was no link with overall cognitive function (which also includes aspects such as language, judgement, fluency of speech and visual thinking). The reason for this was unclear but it suggests the evidence of any link is inconclusive.

Some of the links were stronger in people who carried a form of a gene called APOE-e4, which is a known genetic risk factor for Alzheimer's.

In conclusion, this study does not prove that sleep-disorder breathing is a risk factor for Alzheimer's disease. This study did not specifically look at whether people developed dementia or not. It only looked at their performance on cognitive tests at a single point in time.

These limitations aside, it is important to see your GP for a diagnosis if you suspect you may have sleep apnoea. Left untreated, sleep apnoea may increase the risk of more serious conditions, such as heart attack and stroke.

 

Where did the story come from?

The study was carried out by researchers from Brigham and Women's Hospital (Boston), Harvard Medical School, Beth Israel Deaconess Medical Center (Boston), University of Washington, Wake Forest School of Medicine, US Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, and Stanford University School of Medicine. It was funded by the National Heart, Lung, and Blood Institute in the US.

The study was published in the peer-reviewed medical journal Annals of the American Thoracic Society. Both the Mail and The Sun suggest a link between snoring and Alzheimer's has been found, but this is not the case. A cohort study analysis, where people are assessed for dementia over the course of many years, would be a better way to look at the question.

Also, while it looked at performance on cognitive tests it did not investigate whether people went on to develop dementia. The media also did not mention that it's not possible to say from this type of study whether the breathing problems during sleep are actually the cause of the problems with brain function, because both were measured at around the same time. They also didn't mention that the size of the effect of sleep problems on brain function was small.

 

What kind of research was this?

This was a cross-sectional analysis of data from the ongoing Multi-Ethnic Study of Atherosclerosis (MESA) cohort study in the US. The main goal of MESA is to look at how various lifestyle factors impact on the risk of developing atherosclerosis (hardening of the arteries).

The researchers aimed to see if breathing problems during sleep (sleep-disordered breathing or SDB) were associated with problems in brain functions such as attention and memory. The researchers say that previous studies examining this question have had mixed findings – some showing a link and others not.

They also looked at whether the presence of a variant of the apolipoprotein-E gene called e4 (APOE-e4) also affected the risk of developing problems with brain function. The APOE-e4 variant is a known risk factor for Alzheimer's disease. The Alzheimer's Society report that people with one copy of the variant gene have twice the risk of developing Alzheimer's disease compared to the population at large.

While a cross-sectional analysis can identify a link between two different factors, it cannot prove that one causes the other, as we can't be sure which factor came first. Links identified using this type of study need to be followed up by studies that can identify the sequence of events.

 

What did the research involve?

Researchers analysed sleep and brain function data from participants of the MESA study They looked at whether people with breathing problems during sleep had poorer performance on cognitive tests.

The MESA study involved adults aged between 45 and 84 years old. Study participants underwent a sleep study at home. This involved attaching various monitors to their body overnight to record:

  • episodes of shallow breathing (called hypopneas)
  • episodes of stopping breathing completely (called apnoeas)
  • the levels of oxygen in the blood (oxygen saturation) – as sleep breathing problems can reduce these levels
  • the total time of sleeping
  • the timing of the different stages of sleep

The participants also filled out the Epworth Sleepiness Scale (ESS) questionnaire, which asks various questions to assess whether someone has excessive sleepiness during the day. The minimum score is 0 (no daytime sleepiness) and the maximum score is 24 (most daytime sleepiness).

For each participant the researchers calculated the:

  • apnoea-hypopnea index (AHI) – a measure of how many apnoea and hypopnea episodes a person has per hour of sleep
  • percentage of time during sleep when the oxygen levels in their blood were under 90%

Participants with an AHI score of 15 or more were considered to have moderate to severe sleep disordered breathing. People with an AHI of five or more, and an ESS score of more than 10 were considered to have sleep apnoea.

The cognitive assessment involved three tests that assessed:

  • overall brain function, including areas such as attention, concentration, short and long-term memory and language using the Cognitive Abilities Screening Instrument
  • how quickly the brain could perform tasks (processing speed) and attention using the Digit Symbol-Coding test
  • memory and attention using the Digit Span Test (DST)

The researchers also carried out genetic testing to identify participants with at least one APOE-e4 gene variant (an Alzheimer's "risk gene").

They then compared the cognitive performance of people with the quality of breathing during sleep. They looked at whether results were any different for those people with the APOE-e4 variant. The researchers took into account a number of factors that could affect the results (potential confounders) in their analysis, including:

  • race
  • age
  • body mass index (BMI)
  • level of education
  • smoking
  • high blood pressure
  • depression
  • use of benzodiazepines (a class of drugs used as sleeping pills and tranquilisers)
  • diabetes

 

What were the basic results?

The sleep studies showed that 9.7% of the participants had sleep apnoea, and 33.4% had moderate to severe sleep disordered breathing.

There was no association between AHI score and any of the cognitive outcomes. There was also no link between any of the sleep breathing measures and one of the more challenging cognitive tests used (The DST Backward), or with the test of overall brain function.

Lower oxygen levels in the blood and being more sleepy during the daytime were associated with a small reduction in attention and short-term memory on one cognitive test (the DST Forward). Having sleep apnoea and greater daytime sleepiness were also associated with small reductions in attention and the speed that the brain could process simple mental tasks on another cognitive test.

Some – but not all – of these links were stronger in people carrying at least one copy of the e4 form of the APOE gene (the links were between having lower levels of oxygen in the blood and poorer attention and memory, and between greater daytime sleepiness and poorer attention and speed of brain processing).

 

How did the researchers interpret the results?

The researchers concluded that their results "suggest that more severe overnight [low blood oxygen levels] and sleepiness may be related to poorer cognitive function, especially attention, concentration, and process speed in middle-aged to older adults, and that the risk is greater among carriers of the APOE-ε4 alleles, a known risk factor for Alzheimer's disease."

 

Conclusion

This relatively large cross-sectional analysis has found a link between certain measures of breathing problems during sleep and poorer cognitive function in middle-aged to older adults.

The strengths of this study include its size and use of a prospective sleep study to assess whether people had sleep apnoea or other problems with breathing during sleep. The use of standard cognitive tests is also a strength.

However, the study does have its limitations:

  • The study did have mixed findings – while certain measures of problems with breathing during sleep (e.g. oxygen levels) were associated with cognitive outcomes, others (e.g. Apnea-Hypopnea Index) were not. This suggests that findings are not conclusive. In addition, previous studies have also had mixed results. This suggests that a systematic review which brings together all of the available evidence on this question would be helpful to assess whether, on balance, the research suggests a true link.
  • It's not possible from this type of cross-sectional analysis to prove that breathing problems during sleep cause the differences in brain function seen. This is largely because it's not possible to establish whether participants only developed problems with brain function after they experienced sleep breathing problems. It's also difficult to be sure that the effect of all potential confounders has been removed.
  • The study measured brain function at one time point and did not assess whether people had (or went on to develop) dementia. Therefore we don't know if the brain function differences were temporary or long lasting, whether it had any impact on the participants' lives, or whether there is a link between problems with breathing during sleep and dementia.
  • Sleep was only assessed on one night and may not be indicative of longer term sleep breathing problems.
  • The participants were older and middle aged adults so it may not be possible to generalise these results to younger adults.

Some of the risk factors for sleep apnoea are similar to some of those for dementia. These include being overweight or obese, smoking, and drinking excessive amounts of alcohol.

So maintaining a healthy weight, giving up smoking, and limiting your alcohol intake are likely to reduce both your risk of developing sleep apnoea and dementia.

Links To The Headlines

Snoring linked to Alzheimer's: Difficulty breathing while asleep accelerates memory decline in people at-risk of the condition, reveals study. Mail Online, July 21 2017

Snoring can increase the chances of getting dementia in later life, new study reveals. The Sun, July 21 2017

Links To Science

Johnson DA, Lane J, Wang R, et al. Greater Cognitive Deficits with Sleep-Disordered Breathing among Individuals with Genetic Susceptibility to Alzheimer’s Disease: The Multi-Ethnic Study of Atherosclerosis. Annals of the American Thoracic Society. Published online July 21 2017