Heavy drinking increases stroke risk.

Heavy drinking increases stroke risk

A growing body of epidemiologic evidence is linking heavy alcohol use to strokes. The relationship, say scientists involved in the research, is underappreciated because of the relatively few studies on the matter and because those studies do not prove that alcohol itself is causing the strokes.

Nevertheless, studies of stroke patients in Finland as well as stroke incidence in Honolulu and Framingham, Mass., have shown that men who drink are at a higher risk of stroke. The latest addition to the body of evidence is a British study, reported in the Oct. 23 NEW ENGLAND JOURNAL OF MEDICINE, which found a heavy-drinking/stroke association among hospitalized men.

In the study, 230 stroke patients at Dudley Road Hospital in Birmingham, England, were asked about their drinking habits, as were age-, sex- and race-matched patients hospitalized with problems not related to stroke or alcohol use. The researchers found that drinking more than 300 grams of alcohol weekly -- about 30 drinks -- put men at four times the risk of suffering a stroke as nondrinkers. On the other hand, men who drank lightly -- about one to nine drinks a week -- were at half the risk of nondrinkers.

The researchers calculated these risks after statistically adjusting for two stroke risk factors, hypertension and cigarette smoking. Because only 87 of the stroke patients were women, no conclusive projections for women could be made.

The British study illustrates some of the limitations of retrospective analysis: It relied on the patients' ability to report previous behavior and used other hospitalized patients, who are not necessarily representative of the general population, as a control group.

Even so, the researchers concluded that heavy alcohol intake "is an important and underrecognized independent risk factor for stroke in men." Philip B. Gorelick of Michael Reese Hospital in Chicago, who is preparing the results of his own study for publication, says the connection suggests preventive measures. "Heavy drinking is a reversible risk factor," he says. The current study fits in with the body of evidence, he adds. "I think it's a stepping stone."

Discovering a mechanism by which alcohol causes stroke would firm up the relationship. Strokes result from a disturbance in blood flow to the brain, because a blood vessel has been blocked or has ruptured. Alcohol could induce stroke, the British researchers suggest, by altering the clotting components of blood or by altering blood flow.

Louis R. Caplan, a stroke specialist at Tufts University in Boston, says alcohol theoretically could induce some types of strokes and protect against others. "What needs to be done next," he says, "is to look at alcohol with respect to subdivisions of stroke."