Just a glass of wine or even a pint of beer a day carries significant risk as it can cause changes to the brain equivalent to ageing two years, researchers have found. It is already known that people who drink heavily have alterations in brain structure and size that are associated with cognitive impairments. However, a team from the University of Pennsylvania found that even light-to-moderate alcohol consumption was associated with reductions in overall brain volume. The link grew stronger the greater the level of alcohol consumption, the researchers showed. Going from two to three alcohol units at the same age was like aging three and a half years. The team reported their findings in the journal Nature Communications. “There is some evidence that the effect of drinking on the brain is exponential,” said co-corresponding author Remi Daviet, who was at Penn during the study, and now at the University of Wisconsin-Madison.

“So, one additional drink in a day could have more of an impact than any of the previous drinks that day. That means that cutting back on that final drink of the night might have a big effect in terms of brain ageing.” In other words, Gideon Nave, Penn’s Wharton School: “The people who can benefit the most from drinking less are the people who are already drinking the most.” The researchers looked at brain MRIs from more than 36,000 adults. When the researchers grouped the participants by average-consumption levels, a small but apparent pattern emerged: The gray and white matter volume that might otherwise be predicted by the individual’s other characteristics was reduced. Going from zero to one alcohol unit didn’t make much of a difference in brain volume, but going from one to two or two to three units a day was associated with reductions in both gray and white matter.

Even removing the heavy drinkers from the analyses, the associations remained. The lower brain volume was not localised to any one brain region, the scientists found. And while the researchers underscore that their study looked only at correlations, they say the findings may prompt drinkers to reconsider how much they imbibe.