Women who had up to two drinks a day scored about 20 percent higher on a test of mental ability than women who had less than one a day or didn't drink at all, according to a report in the April 7 issue of Stroke.
It's not startling news, acknowledged study author Dr. Clinton B. Wright, an assistant professor of neurology at the Columbia University College of Physicians and Surgeons in New York City. Other studies have found similar results, most notably one reported last year by a group led by Dr. Meir J. Stampfer that used data from the Nurses Health Study.
This latest study was much smaller, gathering information on 2,215 residents of northern Manhattan. Fifty-four percent of the participants were Hispanic, 25 percent were black, and 21 percent were white.
"The main thing that this study adds is that it had a population that includes a large number of Hispanics," Wright said. "Data on only whites or other ethnic groups is limited in value. It's good to have data from a multi-ethnic cohort."
Stampfer, who chairs the epidemiology department at the Harvard School of Public Health in Boston, agreed. "This adds to the body of data coming from diverse populations around the world," he said.
No statistical association between alcohol intake and mental function was found among men in the study, probably because "only a small group of men were never drinkers," Wright said.
A potentially important finding of the new study was the doubt it cast on the theory that moderate alcohol intake helps preserve mental function by limiting the buildup of fatty plaque deposits in the carotid artery, the main blood vessel to the brain. Using ultrasound to image the carotid artery, the researchers found no relationship between alcohol intake and the amount of plaque in the artery.
One possible explanation is that alcohol improves the flow of blood in smaller arteries, Wright said. The Columbia researchers plan further studies to explore that possibility.
"Another possibility is that the amount of plaque is not the relevant factor," Wright said. "The tendency to form clots or the tendency to inflammation might be more important."
"Small arteries probably are important, and there might be other mechanisms as well," Stampfer said. The results are no reason for nondrinking women to sip a glass or two, Wright said. "I don't think anybody should change behavior based on this study alone," he said.
The standing advice of the American Heart Association and other bodies stands, Stampfer said. For older men with no complicating issues, such as a prior drinking problem, "a moderate, one or two drinks a day, regular intake of alcoholic beverages is more likely to be beneficial than harmful, as long as nutrition is adequate," he said.
The picture is more complicated for women because of an association between drinking and breast cancer, Stampfer said. But "the net effect is toward benefit for women as well," he said. "Moderate for women is up to one drink a day."