Knowledge about Excess Drinking Shrinks the Brain

"The take-home message is that, if you drink a lot, you're going to hurt your brain," said Rajesh Miranda, an associate professor of neuroscience and experimental therapeutics at the Texas A&M Health Science Center College of Medicine. "This is something we knew, but this is a huge study that quantifies that."

"It's not surprising that alcohol would cause shrinkage of the brain. That kind of thing has been observed in animal models and smaller studies," Miranda added. "The surprising thing is that they [the study authors] showed that even low levels of drinking are not protective, as people had seen in other cases."

The findings are published in the October issue of the Archives of Neurology.

Brain volume decreases naturally as people age, at a rate of about 1.9% per decade. At the same time, the brain acquires white matter lesions as it gets older. Both of these changes also accompany dementia and cognitive decline, according to background information in the study.

Moderate levels of alcohol consumption have been linked with a decreased risk of cardiovascular disease, leading researchers to hypothesize that restrained tippling might also slow declines in brain volume. Previous studies have also found that drinking alcohol in moderation is associated with improved cognitive function and a decreased risk of Alzheimer's disease.

For the new study, led by Carol Ann Paul, of Wellesley College in Massachusetts, researchers conducted magnetic resonance imaging (MRI) and health exams on 1,839 adults (average age 60) participating in the Framingham Offspring Study between 1999 and 2001. None of the participants had evidence of clinical dementia or had suffered a stroke.

The men and women were asked how much alcohol they drank each week, then were classified as abstainers, former drinkers, or low (one to seven drinks per week), moderate (eight to 14 drinks per week) or high consumers of alcohol (more than 14 drinks a week).

Most participants (almost 38% of men and more than 44% of women) fell into the "low-consumption" category. Men were more likely than women to report being moderate or heavy drinkers.

Alcohol had no protective affect on the normal, age-related shrinkage in brain volume, the researchers found.

To the contrary, the more a person drank, the more their brain volume diminished. This relationship was somewhat more pronounced in women, although women tended to be lighter drinkers.

The gender difference could be explained by biological factors, namely that alcohol is absorbed faster in women and they tend to feel the effects of alcohol more than men, the researchers said.