BOSTON, May 3 -- Heavy drinking takes a toll on brain size, with a shrinking effect equivalent to about one to two years of brain aging for every higher level of alcohol consumption, investigators reported here.
Even light drinking had no beneficial effect on brain aging, unlike an often-reported cardiovascular benefit found from mild levels of alcohol, reported Carol Ann Paul, M.S., a senior instructor at Wellesley College in Wellesley, Mass.

The cross-sectional study of more than 1,800 patients was designed to determine whether the cardiovascular benefits associated with light-to-moderate alcohol consumption could also be seen in the brain, said Paul at the American Academy of Neurology meeting here.

Those who reported more than 14 alcoholic drinks per week had a significantly smaller brain volume compared with non-drinkers.

"Brain volume normally declines with age and that's often accompanied by cognitive impairment in the later stages," she said. "So brain volume is some sort of indicator of brain capacity."

She and her colleagues took advantage of MRI scans acquired from 1999 to 2002 from 1,839 non-demented participants in the Framingham Offspring Study, which itself is an offspring of the Framingham Heart Study.

They divided the participants into five categories on the basis of self-reported alcohol consumption frequency: abstainers, former drinkers, low drinkers (one to seven drinks per week), moderate drinkers (eight to 14 drinks per week), and heavy drinkers (more than 14 drinks per week).

The authors made pair-wise comparisons of mean total cranial volumes across the various groups, and created multivariate linear regression models to see whether there was an association between brain size and alcohol consumption. They controlled their analyses for age, gender, body mass index, height, educational level attained, and Framingham Stroke Risk Profile. They also looked at the longitudinal history of alcohol consumption from 1987 to 2001 to see whether there were associations with total cranial volume.

"I found that unlike what I had hypothesized, there was no beneficial effect of alcohol on brain volume," Paul said. "In addition, I found that there was a slightly more strong effect in women than in men, and on the preliminary longitudinal studies, it seemed that people who had been heavy drinkers throughout the 12-year period we looked at, had significantly decreased brain volume in comparison to the others."

Specifically, the authors found a reduction in brain volume of 0.25% for every additional category of alcohol consumption. In contrast, the average age-related decline in brain volume is 0.19% per year, she noted.

Gender modified the alcohol-brain volume relationship significantly (P=0.0029), with men having a slightly lower downward slope than women, meaning that brain volume decreased more in women than men across categories of alcohol consumption.

The authors also detected a significant negative correlation between alcohol consumption and brain volume among women in their 70's (P= 0.013), and in the longitudinal analysis, they found that heavy drinking was negatively associated with brain volume (P=0.005, -0.026).

"Each drink category is approximately equivalent to one-to-two years of aging," Paul said, adding that the effect was linear across the categories from low to high.

She suggested that although alcohol consumption in moderation has beneficial effects on the cardiovascular system, it may be found to be associated with deleterious effects on neurons and neural circuitry.

Neither funding sources nor author conflicts of interest were reported.
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Primary source: American Academy of Neurology 2007 Annual Meeting
Source reference:
Paul CA et al. "The Effect of Alcohol Consumption on Total Brain Volume: The Framingham Heart Study." Abstract P05.030, presented May 2.

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