You might want to consider your brain before knocking back another drink, and not just for fear of a hangover.
According to a study by researchers at UC Davis, Wellesley College and Boston University, the more alcohol people consume, the more their brain volume decreases.
The implications of this preliminary study are far from clear, but any loss in brain tissue may predispose people to cognitive impairment later in life, said study co-author Charles DeCarli, a professor in the department of neurology at UC Davis.
Prior studies have suggested that moderate drinking – eight to 14 drinks a week – lowers the risk of cardiovascular disease, dementia and Alzheimer’s disease. This led to speculation that small amounts of alcohol may also protect against normal age-related brain shrinkage. However, the new study has shown that all levels of consumption are associated with measurable losses in brain volume.
“This finding is clearly at odds with the long and widely held belief that what is good for your heart is good for your brain,” said Beth Ober in an e-mail interview, a professor of human development at UC Davis who was not involved in the study.
The two-year study included 1,839 healthy adults, aged 33 to 88 years, with an average age of 60. During a health examination, participants reported the number of alcoholic drinks they consumed per week and underwent magnetic resonance imaging (MRI) of the brain.
Earlier studies on brain shrinkage were based on autopsies and thus often limited in scope to the very old or very sick, said Roger McDonald in an e-mail interview, a professor of nutrition at UC Davis who was not involved in the study.
“Brain imaging is a biological marker of brain disease that is more subtle than either the presence or absence of dementia,” DeCarli said. “This [study] looks at how the brain changes with age and alcohol use before any symptoms are present.“
On average, individuals who drank more than moderate amounts of alcohol had 1.5 percent less total brain volume than lighter drinkers. To a lesser extent, this negative relationship still held with the moderate and low consumption groups of drinkers and still remained significant after controlling for other factors such as age, sex, BMI, and history or risk of vascular disease and stroke.
The results also show a stronger correlation between drinking and brain volume in women than in men. Age-related changes in the brain begin to accelerate in post-menopausal women, so the findings suggest that alcohol may exacerbate this process, DeCarli said.
Follow up studies with the same adults over many years are needed to distinguish the effects of aging from the effects of alcohol on brain shrinkage, Ober said.
Follow up MRI measurements are in progress, DeCarli said. Further studies are needed to understand the cause of brain tissue loss that is associated with excessive drinking, and to determine what a healthy amount of alcohol for consumption really is, he said.
It may be that alcohol in association with other unhealthy activities like smoking is injuring the brain, he said.
“Individual assessments for memory, attention and reasoning should also be carried out to determine what the impacts of brain shrinkage are on cognitive functions over time,“ Ober said.
Ober also noted that in comparison to the normal age related brain shrinkage rate of 2 percent per decade, the overall changes observed in the study seem rather small.
“If even a small change in brain volume [with] alcohol consumption is significantly associated with a decline in cognitive function, then it is worth worrying about,” she said.
There is no evidence yet that alcohol has similar effects on the brains of younger adults, but DeCarli advises against excessive drinking that could lead to alcoholism in the long run.
“If you’re having two drinks a day when you’re in college [the upper limit of moderation], it’s likely you’re going to be drinking much more than that by the time you get out of college and into middle age,” he said.
ELAINE HSIA can be reached at firstname.lastname@example.org.