This finding may be due to the immediate effects of alcohol, which increases blood pressure and causes blood platelets to become stickier, perhaps increasing the risk of clotting, the authors noted.
But drinking small amounts of alcohol over time appears to have a beneficial effect on blood fats and may make blood vessels more flexible, which might reduce the risk of heart attack and stroke, the researchers said.
Stroke is the third-leading killer and a major cause of long-term major disability in the United States, according to the American Heart Association.
Dr. Larry B. Goldstein, a professor of neurology and director of the Duke Stroke Center at Duke University Medical Center and a spokesman for the American Heart Association/American Stroke Association, said that "current guidelines indicate that for people who drink, men should consume no more than two alcoholic beverages per day and women no more than one, and women should abstain during pregnancy."
Evidence suggests that light to moderate alcohol consumption in this range is associated with a reduction in stroke risk, but heavier drinking is associated with an increase in stroke risk, he said.
"This new research suggests that the risk of stroke may be transiently increased in the first hour after drinking even small amounts of alcohol. But, the numbers of patients were too small to determine whether this risk varied depending on the type of alcohol consumed," Goldstein said.
The findings should not necessarily deter moderate drinking, he added.
"For those who consume alcohol, this transient increase in risk needs to be balanced against the potential long-term reduction in risk with mild-moderate consumption," he said.
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