Even one drink a day can shrink your brain. That’s the finding of a recent study of more than 36,000 men and women. While heavy drinkers had the greatest risk for reduced brain size, the link was evident even in moderate drinkers. This study refutes current guidelines that a little alcohol does not negatively affect the brain, and may even have benefits.

According to Axios, University of Wisconsin and University of Pennsylvania analyzed brain MRIs of more than 36,000 men and women included in the UK Biobank, a dataset of genetic and medical information on 500,000 British middle-aged and older adults. The MRIs calculate white and gray matter volume in different regions of the brain, says Penn Today.

The researchers factored in variables such as age, height, gender, BMI, smoking and socioeconomic status. Those who drank the most alcohol had the greatest changes in brain size and function associated with cognitive impairment from aging.  But that correlation was also noticed in moderate drinkers.

The study found that alcohol consumption even at levels most would consider modest — a few beers or glasses of wine a week — may carry risks to the brain, according to Penn Today. The link grew stronger the greater the level of alcohol consumption. For example, in 50-year-olds, as average drinking among individuals increased from one alcohol unit (about half a beer) a day to two units (a pint of beer or a glass of wine), the associated brain changes were equivalent to aging two years. The MRIs revealed that going from one to two to three units a day was associated with reductions in both gray and white matter.

The more people drank, the greater the aging effect on the brain. Going from zero to four drinks a day was the equivalent of more than 10 years of aging. But even lesser amounts caused significant reduction in grey and white matter of the brain.

“These findings contrast with scientific and government guidelines on safe drinking limits,” said Dr. Henry Kranzler, a professor of psychiatry and director of the Center for studies of Addiction and the University of Pennsylvania’s Perelman School of Medicine.

 He pointed out that the National Institute on Alcohol Abuse and Aging recommends that women consume an average of no more than one drink daily and men should consume no more than two drinks a day.

“That exceeds the consumptions levels associated in the study with decreased brain volume,” said Kranzler in a statement.

It’s important to note that the study didn’t look at causation but rather correlation between drinking alcohol and reduced brain size, says Axios. But the researchers hope to pinpoint why alcohol causes these brain changes in future studies. Still, the message is loud and clear that cutting back on drinking can save your brain.

“The people who can benefit the most from drinking less are the people who are already drinking the most,” said Gideon Nave, one of the authors of the study and faculty member at Penn’s Wharton School.