‘No safe amount’: All alcohol consumption ‘harmful to the brain’

There is no safe amount of alcohol consumption for the brain, with even “moderate” drinking adversely affecting nearly every part of it, a study of more than 25,000 people has found.

The British study, which is still to be peer-reviewed, suggests that the more alcohol consumed, the lower the brain volume. In effect, the more you drink, the worse off your brain.

"There's no threshold drinking for harm – any alcohol is worse. Pretty much the whole brain seems to be affected – not just specific areas, as previously thought," says the lead author, Anya Topiwala, a senior clinical lecturer at the University of Oxford.

Higher alcohol consumption was associated with lower grey-matter density, the researchers found. It had four times the effect on brain health of smoking or BMI

Using the UK Biobank, a substantial database designed to help researchers decode the genetic and environmental factors that lead some people to develop diseases while others do not, researchers in this study analysed data from 25,378 participants such as age, sex, education, self-reported alcohol consumption, brain size and health from MRI scans, information about hospital and outpatient visits, and memory tests.

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Higher volume of alcohol consumption per week was associated with lower grey-matter density, the researchers found, with alcohol explaining up to a 0.8 per cent change in grey-matter volume, even after accounting for individual biological and behavioural characteristics.

This might seem like a small figure, but it is a larger contribution than any other modifiable risk factors. For example, it is four times the contribution of smoking or BMI, says Topiwala.

Widespread negative associations were also seen between alcohol consumption and integrity of white matter, the brain fibres that scaffold the billions of neurons that make up grey matter. In addition, high blood pressure, high BMI and other underlying conditions made the negative association between alcohol and brain health stronger, the researchers have found.

Contrary to previous research that suggested there is a benefit to drinking wine in moderation compared with beer or spirits, the study found no evidence to suggest the type of alcoholic beverage led to different risks to the brain.

The study shows evidence of harm below the guidelines for weekly alcohol consumption, according to Anya Topiwala of the University of Oxford, who led the study

The associations of wine-drinking with higher educational attainment and socioeconomic status may explain the perceived health benefits, the authors suggest. “If you look at who is moderately drinking, at least in the UK, they are better educated, wealthier people that would do much better on a memory test … just because of who they are, than people that are less educated,” says Topiwala.

The findings are robust to many alternative assumptions, says Colin Angus, a senior research fellow from the alcohol research group at the University of Sheffield.

“In the grand scheme of things, these effects appear small, although it’s hard to compare them against the impact of alcohol on other health outcomes, such as increased risks of cancer, without further research to understand how the association between alcohol and brain health feeds through into more tangible outcomes, such as dementia or Alzheimer’s.”

The HSE's guidelines recommend that women consume no more than 11 units of alcohol a week and men no more than 17, spread out over the week, with two or three alcohol-free days a week and no more than six units on any one occasion. In Ireland a unit contains about 10g of pure alcohol – the equivalent of a pub measure of spirits, a small glass of wine, half a pint of beer, or an alcopop.

UK guidelines recommend that both men and women drink no more than 14 units of alcohol each week. In the UK a unit contains about 8g of pure alcohol. Topiwala says the study shows evidence of harm below this threshold. – Guardian