"Sex is the key to staying sharp in old age," reports the Mail Online after researchers found older people who have regular sex scored better on two of five brain tests.
Participants who had sex at least once a week scored higher on tests that measured their verbal fluency and spatial awareness compared with those who had no sex at all.
The verbal fluency test involved asking participants to say as many words beginning with a letter – in this case "f" – in a minute, and also name as many animals as they can.
In the spatial awareness test, participants had to draw an image, such as a square, triangle, cube or pyramid, and draw a clock face from memory.
These tests are part of the Addenbrookes Cognitive Examination III (ACE-III) test, a standard test to measure brain function.
The study involved 73 people aged between 50 and 83, and was conducted by researchers at the universities of Coventry and Oxford.
Researchers say their results "demonstrate that older men and women who engage in regular sexual activity have better cognitive functioning than those who do not … or do so infrequently".
But it's not clear why.
Previous studies have shown that older people who have active social lives and keep physically active are likely to have better cognitive function.
It's possible the social or physical elements of sexual activity are simply another aspect of this previous finding.
Researchers speculated it could also be caused by the release of dopamine, a chemical that transmits information in the brain during activities like sex.
We can't draw any conclusions from this study about whether sex keeps the brain functioning well, or whether people with better cognitive function are more likely to continue to have sex – or if the link is caused by something else entirely.
The study was carried out by researchers from Coventry University and the University of Oxford.
It was funded by the Coventry University Pump-Prime Research Grant Scheme.
The study was published in the peer-reviewed Journals of Gerontology and is free to read online.
The Mail Online's story was mostly accurate, although the reporting assumed that increased sexual activity was the cause of better cognitive function, which may not be the case.
Most of the media coverage made the same error. The i newspaper stated that, "Having more sex can boost brain power", while The Sun incorrectly informed readers that, "Testers aged up to 83 were asked to keep a bonking diary".
This was a cross-sectional observational study. This type of study can show an association between different things, but can't tell whether one thing (in this case sexual activity) causes the other (cognitive function), or whether other factors are at play.
Researchers recruited 73 volunteers over the age of 50: 45 women and 28 men.
They were asked to say how often they'd had sex over the past year:
They then filled out a general health questionnaire and took a range of tests designed to assess their mental abilities.
Researchers then looked at whether people who said they'd had sex never or monthly did better or worse on the tests than people who said they'd had sex weekly.
The researchers used the Addenbrookes Cognitive Examination III (ACE-III) test, which includes brief measures to assess people's abilities in attention, memory, fluency, language, and visual-spatial fields (how well people can visualise things in relation to those around them).
They adjusted their figures to account for people's age, years in education, gender, and cardiovascular health, as these factors might affect both how often they had sex and their cognitive abilities.
Frequency of sexual activity didn't vary significantly by age, education level, cardiovascular health, or other factors measured.
People who said they'd not had sex in the past year had on average lower scores for overall cognitive function and fluency compared with those who said they'd had sex weekly.
People who reported having sex monthly had on average lower scores for fluency and spatial awareness, although the difference here was small and may just have been down to chance.
More people in the group of 73 said they'd had sex weekly than monthly or never. All 10 of the respondents who said they never had sex were women.
More women than men said they'd had sex monthly (65% women and 35% men), and about equal numbers of men and women said they'd had sex weekly.
The researchers say their results "demonstrate that older men and women who engage in regular sexual activity have better cognitive functioning than those who do not … or do so infrequently".
They suggest this might be because of the biological effect of dopamine, a chemical that transmits information in the brain, and is linked to pleasure and reward pathways.
They say that, "We can only speculate that continued engagement in regular sexual activity may have a positive influence on cognitive function", but add "the findings have important implications for the maintenance of intimate relationships in later life".
This study got widespread and enthusiastic coverage in the media, as many studies about sex do. But the findings are limited and it's difficult to draw conclusions from them.
As the researchers point out, we already know that a healthy social life and staying physically active seem to help keep people's cognitive abilities sharper as they age.
It's not a surprise that sexual activity, which has elements of both social and physical activity, is also linked to better cognitive function.
But this small observational study only provides a snapshot in time of how sexual activity may link to brain function.
We can't draw any firm conclusions about whether sexual activity keeps the brain functioning well, or whether people with better cognitive function are more likely to continue to have sex.
The results of the study are quite limited. Although overall scores of cognitive function were better for people who reported having sex weekly, this seems to have been driven by only two of the five types of mental ability, and the relationships weren't consistent.
And it's hard to explain how having sex monthly could give you worse spatial awareness than either having sex weekly or not at all, for example.
While continued sexual activity may be pleasurable and generally healthy into older age, this study doesn't mean it's a panacea for keeping the brain sharp.
If you're older and don't want to engage in sexual activity, the results of this study don't mean there's any reason to worry about it.