Aspirin Found to Cut Down Occurrence of Migraine : Medicine: Researchers say taking one every other day can reduce the rate of headaches by 20%.

Taking an aspirin every other day can significantly cut down on the occurrence of migraine, according to new research that offers hope to many of the estimated 25 million Americans who suffer from the excruciating, inexplicable headaches.

The finding, published today in the Journal of the American Medical Assn., suggests yet another surprising new use for the old drug. Over the past few years, aspirin has been found to prevent heart attacks, stroke and pregnancy-induced hypertension.

“Migraines are incredibly debilitating,” said Dr. Julie Buring, a Harvard Medical School professor and co-author of the new paper. “. . .The hope is that they can be prevented rather than have to be treated once you get them.”

There is no widely accepted means of preventing migraine--intense and chronic headaches often accompanied by nausea. The drugs most commonly tried are heart-disorder drugs that often cause serious side effects.

The new findings emerged from a now-famous study of more than 22,000 male physicians exploring the value of taking a single aspirin every other day in preventing heart attacks, cataracts, angina, periodontal disease and a host of other conditions.

In the study, 6% of the physicians who took aspirin, compared with 7.4% of those who did not, reported having had a migraine during the study period. That suggests that aspirin reduced the migraine recurrence rate by 20%, the researchers concluded.

Though the study did not explore whether regular doses of aspirin reduced the severity and duration of the headaches, the researchers said participants in the study told them that the treatment did have that effect.

“I don’t think it’s a magic bullet in terms of a preventive factor for migraine,” said Buring, an associate professor of preventive medicine at Harvard University and Brigham and Women’s Hospital. “But right now, there’s not a tremendous amount we have to offer people.”

Several specialists in the field said they were not surprised by the finding.

Dr. Neil Raskin, a professor of neurology at UC San Francisco, said he would have expected that aspirin might help those people with recurring headaches not severe enough to drive them to a doctor. But he said he thought it would be of little help to those with disabling headaches.

Dr. D. J. Dalessio, a consultant in neurology at Scripps Clinic and Research Foundation in La Jolla, said many patients already take aspirin in hopes of preventing migraines. He said he would suggest it for people with migraines occurring at least weekly.

Aspirin is not without side effects. Because it works by thinning the blood, it can be dangerous for people with bleeding ulcers, and it can cause nausea, indigestion, heartburn, stomach problems and constipation in some patients.

Researchers theorize that aspirin works against migraines by controlling the release of serotonin, a chemical believed to help trigger migraines. Serotonin is released by blood platelets when them stick together; aspirin inhibits that clumping together of platelets.