An aspirin every other day may help prevent migraines among some of the millions of Americans who suffer the excruciating headaches, scientists reported Wednesday.

The findings in the Journal of the American Medical Association are from the same study that found aspirin effective in preventing a first heart attack.The researchers found that a group of men who took one aspirin every other day reported 20 percent fewer migraines than a similar group that took a dummy tablet.

Headache experts called the research results encouraging. But they said aspirin could offer, at best, only a partial solution to the migraine puzzle.

Nevertheless, "there's enough evidence here that health-care practitioners should consider aspirin for migraine treatment," said Julie E. Buring, leader of the team at Boston's Brigham and Women's Hospital that reported the findings.

An estimated 20 percent of American adults suffer migraines. Headache experts say there is no known single cause of migraines. The severe headaches, often accompanied by nausea, appear to be triggered in some patients by certain foods and also seem related to stress and a lack of regular sleep, meals and exercise.

Buring and her colleagues analyzed five years of data from the Physicians Health Study, a project involving about 22,000 U.S. male physicians that began in 1982.

The project is devoted to studying the effects of aspirin and beta carotene, an orange pigment found in certain fruits and vegetables, on heart disease, migraine and cancer.