Drinking Can Help and Harm the Brain
Excerpt by Amy Norton, Reuters Health

NEW YORK (Reuters Health) - When it comes to alcohol's effects on older people's brains, there is good and bad news, researchers say.

Light drinking, and even relatively heavy alcohol intake, appears to protect elderly adults from small blockages in brain blood vessels known as ``silent strokes.'' The trade-off is that drinking of any kind may help kill off brain cells, according to a report in the September issue of Stroke: Journal of the American Heart Association.

Given this complex relationship between drinking and the brain, it is too soon to make recommendations to older people on alcohol use, researchers explain.

``This highlights how difficult it is to make public health recommendations on alcohol use,'' the study's lead author, Dr. Kenneth J. Mukamal of Beth Israel Deaconess Medical Center in Boston, Massachusetts, told Reuters Health.

Many studies have found moderate drinking--particularly wine consumption--to be beneficial to heart health. As for the brain, the effects are less clear, Mukamal pointed out.

But some evidence shows moderate drinking can help ward off stroke, while heavy drinking may increase the risk. There is also evidence that a drink a day helps preserve people's mental functioning as they age, but too much alcohol can cause the brain to shrink over time, which in turn has been linked with poorer brain function.

In the current study, Mukamal's team looked at the brain structure and alcohol intake of nearly 3,400 men and women aged 65 and older. Using MRI brain scans, the investigators looked for evidence of tissue damage from silent strokes. They also searched for signs of brain atrophy, or shrinkage, and small areas of scarring in the brain's white matter--subtle damage that has been linked to declines in brain function, according to Mukamal.

All participants were questioned on their drinking habits in recent years and assessed for other health and lifestyle factors that could affect the aging brain.

The researchers found that, when all factors were considered, moderate drinkers (about a drink per day) had a lower risk of silent stroke and white matter abnormalities, compared with abstainers. Heavy drinkers (15 or more drinks per week) had the lowest silent stroke risk, but were about as likely as teetotalers to show white matter abnormalities.

And compared with nondrinkers, those who consumed any alcohol regularly were more likely to show brain atrophy--with the risk increasing in tandem with alcohol use.

A conspicuous discrepancy between these findings and past research is the fact that heavy drinkers had a decreased risk of silent stroke. In fact, these individuals were 43% less likely than abstainers to show signs of such damage. According to Mukamal's team, this may be due to how they defined ``heavy'' alcohol consumption. In many other studies, they note, 15 drinks per week would be considered moderate.

``It is certainly not true that drinking to infinity will decrease (stroke) risk,'' Mukamal said, adding that the weight of the evidence suggests heavy drinking does raise the risk.

Brain atrophy--a signal of brain cell death--has previously been linked with drinking. It is possible that while alcohol can ward off stroke by improving cholesterol levels or helping to thin the blood, it can also lead to brain atrophy by directly injuring cells, the report indicates.

However, Mukamal pointed out, cell death does not fully explain the brain shrinkage seen with heavy drinking, since studies of alcoholics show some brain atrophy can be reversed.

``This all gets back to the notion that alcohol has myriad effects...both for the good and the bad,'' he said.

For older people, he noted, the decision to drink or not to drink--or cut back--must be made on an individual basis, with a doctor's advice.

SOURCE: Stroke 2001;32.

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