I'm Gwen Outen with the VOA Special English Health Report.

A lot of older people take low-strength aspirin on the advice of their doctor to help reduce the risk of heart attack or stroke. Doctors have based such advice mostly on studies of men.

Now, a major study confirms that aspirin can help women as well. But experts say the drug helps women differently. The findings appeared this month in the New England Journal of Medicine.

Doctor Julie Buring at Brigham and Women's Hospital in Boston, Massachusetts, led the study. Doctor Buring says that among apparently healthy people, aspirin reduces the risk of heart attack for men. But for women it appears to reduce the risk of stroke.

The study involved forty thousand women age forty-five and older. Those who received aspirin took one hundred milligrams every other day. The others took a placebo, an inactive pill.

The study lasted ten years. The researchers found that the women who took aspirin were seventeen percent less likely to have a stroke than the other group. The aspirin group also had a twenty-four percent lower risk for the most common form of stroke. This is caused by a clot in the blood supply to the brain. Blood clots can cause both strokes and heart attacks. Aspirin thins the blood, so clots are less likely to form.

The researchers found that aspirin had an even greater effect in women age sixty-five and older. Those who took aspirin were thirty percent less likely to have a stroke caused by a blood clot. They were also less likely to suffer a heart attack than those given a placebo.

However, the study found that aspirin did not lower the risk of heart attack in younger women. And there were more cases of stomach bleeding in the women who took aspirin than in those who did not. Experts say this shows that, in general, the risks from aspirin use in younger women could be greater than the good it might do.

Aspirin can cause bleeding, especially in the stomach. It can also cause a bad reaction with other medicines. People who want to begin aspirin treatment are advised to talk to their doctor first.

Experts are not sure why men and women react differently to aspirin treatment. But Doctor Buring notes at least one similarity. She says aspirin has been clearly shown to improve the survival chances for anyone who has already had a heart attack or stroke.

This VOA Special English Health Report was written by Cynthia Kirk. I'm Gwen Outen.