Does a drink a day shrink the size of your brain?

The study's findings show a need for more research into how alcohol affects our health.

Dave Yasvinski 4 minute read March 7, 2022
man holding glass of liquor, long angle

Previous research has linked heavy alcohol use to changes to the structure of the brain. GETTY

A drink a day may be all it takes to reduce the size of your brain, according to a new study that says the effect is magnified as consumption increases.

The research, published in the journal Nature Communications, found that consuming even light-to-moderate amounts of alcohol was associated with a decrease in the size and structure of the brain. The relationship was discovered after researchers analyzed the brain scans of more than 36,000 patients included in the UK Biobank, a database containing the health information of half a million British adults.

“The fact that we have such a large sample size allows us to find subtle patterns, even between drinking the equivalent of half a beer and one beer a day,” said Gideon Nave, a corresponding author on the study and faculty member at the University of Pennsylvania’s Wharton School. “Having this dataset is like having a microscope or a telescope with a more powerful lens. You get a better resolution and start seeing patterns and associations you couldn’t before.”

“It gets worse the more you drink”

In 50-year-olds, for example, as alcohol consumption increased from an average of one unit a day (half a beer) to two units a day (a pint of beer), there were associated changes in the brain that resembled two years of aging. Increasing consumption from two to three units was equivalent to three and a half years of aging.

“It’s not linear,” co-corresponding author Remi Daviet. “It gets worse the more you drink.”

While previous research has linked heavy alcohol use to changes to the structure of the brain, other findings have been more ambiguous, with some studies suggesting that lower levels of consumption may not be harmful and may even be beneficial. Researchers attempted to settle the matter by applying the power of large datasets to their investigation.

The team divided subjects from the UK Biobank into groups based on how much alcohol they consumed — from abstention to four or more units per day — and analyzed their MRI results to calculate the corresponding levels of white and grey matter in their brains. After controlling for other variables that could impact the relationship (such as age, height, handedness, sex, smoking status, socioeconomic status, genetic ancestry and county of residence) a small pattern became apparent: the amount of grey and white matter volume that should be present based on their other characteristics was reduced.

The team compared reductions in brain size from drinking to those that occur naturally through aging to highlight the impact of the issue. According to their modelling, each unit of alcohol per day had a greater impact on this aging effect. Going from zero to one, for example, only aged the brain by half a year. Going from zero to four, however, was equivalent to more than 10 years of aging.

The team hopes further research will provide additional information on the risks of alcohol abuse and prove cause and effect where only correlation currently exists. “This study looked at average consumption, but we’re curious whether drinking one beer a day is better than drinking none during the week and then seven on the weekend,” Nave said. “There’s some evidence that binge drinking is worse for the brain but we haven’t looked closely at that yet.”

The study had a few limitations, most notably that researchers only had information on the drinking habits of participants in the year prior to their MRI scans. “I think this is a major limitation as it’s likely that the cumulative consumption of alcohol throughout one’s lifetime is associated with the brain, not just the level of consumption right before the images were taken,” said Emmanuela Gakidou, a professor of health metrics sciences at the University of Washington, according to CNN.

“The relationship between alcohol and health is complex, and our understanding of that relationship is evolving over time. Based on this study, I would not really draw any definitive conclusions but I would say that the authors have identified areas for further research.”

Dave Yasvinski is a writer with Healthing.ca

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