That sounds pretty serious, so let's break down what it actually means. All the participants of the study — which was published in The BMJ last month — were enrolled in the UK's Whitehall II study, which looks at health and stress. None of the participants were deemed alcohol dependent.
What researchers found was that the people who drank the most had the highest risk of hippocampal atrophy, which is a form of brain damage often associated with memory-loss conditions like Alzheimer's and dementia. The heavier drinkers also had a faster decline in language skills and poorer white matter integrity, which is what helps us to process thoughts in a prompt manner. That part was not necessarily surprising, and seems to back up other research which has also shown that heavier drinkers are more at-risk for changes to their brain over long periods of time.
What was surprising to researchers, however, was that moderate drinkers appeared to change, too, and they had higher risk of hippocampal atrophy than non-drinkers. "We were surprised that the light to moderate drinkers didn't seem to have that protective effect," study co-author Dr. Anya Topiwala, a clinical lecturer in the Department of Psychiatry at the University of Oxford, told CNN. "These are people who are drinking at levels that many consider social drinkers, so they are not consuming a lot."
Moderate drinking was defined by the study as consuming the equivalent of a medium glass of wine each night, with a little extra on the weekends. By way of comparison, the heaviest drinkers in the study were consuming a bit more than two medium glasses of wine or two beers every night of the week.
But you shouldn't fret about having to give up your booze just yet. There's no real evidence to show how clinically significant this change to the brain is in moderate drinkers. Plus, Eric Rimm, a professor of medicine and director for the program in cardiovascular epidemiology at Harvard T.H. Chan School of Public Health, told CNN, "There are so many other lifestyle factors that are not taken into account in this study, like nutrition. Eating whole grains and fruits and vegetables have been linked with slower cognitive decline." He also cautioned that attributing mental decline to alcohol is too limited.