Many studies have examined the link between drinking alcohol and brain health, with ambiguous results. Strong evidence exists that heavy drinking causes significant changes in brain structure, such as severe reductions in gray and white matter across the brain. However, some studies suggest that moderate drinking may not have much impact on brain health, or even that light drinking is beneficial for the brains of older adults.
However, these earlier investigations lacked the power of large datasets. A new study led by the University of Pennsylvania has analyzed data for over 36,000 adults and found that alcohol consumption even at levels most would consider modest, such as a few beers or glasses of wine per week, carry major risks to the brain and are associated with reductions in the overall brain volume.
“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 study corresponding author Gideon Nave, an assistant professor of Marketing at the University of Pennsylvania. “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.”
By analyzing data from the UK Biobank, containing genetic and medical information about half a million British middle-aged and older adults, Professor Nave and his colleagues have found that going from zero to one unit of alcohol per day (approximately half a beer) did not make much of a difference for brain volume, but increasing from one to two or two to three units was associated with reductions in both gray and white matter. In fact, consuming two units of alcohol per day was associated with changes in the brain equivalent to aging two years.
“These findings contrast with scientific and governmental guidelines on safe drinking limits,” said study co-author Henry Kranzler, the director of the Penn Center for Studies of Addiction. “For example, although the National Institute on Alcohol Abuse and Alcoholism recommends that women consume an average of no more than one drink per day, recommended limits for men are twice that, an amount that exceeds the consumption level associated in the study with decreased brain volume.”
Future research is needed to assess what are the effects of binge drinking on brain health. “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. There’s some evidence that binge drinking is worse for the brain, but we haven’t looked closely at that yet,” Professor Nave concluded.
The study is published in the journal Nature Communications.