Recent studies on the effects of regular doses of aspirin on men have found a significant reduction in the risk of a heart attack.

Beginning this year, a five-year project at Harvard will provide the most thorough information to date on whether similar effects take place among women.

After initial doubts among federal officials as to whether funding for such a study was necessary, the National Heart Lung and Blood Institute last summer decided to provide the $10 million for the research.

The experiment, which is called the "Women's Health Study," is being conducted at the Harvard Medical School and the Harvard-affiliated Brigham and Women's Hospital in Boston.

Nurses to Be Studied

Charles H. Hennekens, associate professor of preventive medicine and clinical epidemiology at the Medical School, is heading the study, which will randomly select 45,000 registered nurses over 50 years old from across the country.

In selecting the nurses who will participate in the study, Hennekens says, there will be "a special effort to enroll minorities" because minorities have frequently been neglected in previous medical experiments of this type. "They are underrepresented in these generalized studies," he says.

Initially, a detailed survey will be sent out to these nurses to determine their relative health. The nurses will be asked about their previous health problems and their histories of heart disease.

The nurses will then be given either low doses of aspirin or a placebo for the duration of the study and their health will be regularly monitored in order to evaluate the aspirin-heart attack relationship.

The experiment will be double-blind, which means that not only will the nurses not know whether they have been given the aspirin or the placebo, but the researchers will not know either.

Past Research

Previous studies have shown that aspirin can reduce the risk of heart attacks by interfering with the clotting of blood. Most heart attacks occur when blood vessels are narrowed and there is difficulty with blood flow. A blood clot may then develop in the vessel and block it.

One of the most conclusive studies of the effect of aspirin on this process in men was conducted by Hennekens in 1982. Those results, obtained from a large sample of physicians, suggested that regular doses of aspirin reduced the risk of heart attacks.

Female physicians, however, were not included in that study because there were so few women doctors over 40 at that time, Hennekens has said.

Since men and women may respond differently to aspirin, Hennekens says, he felt that there was a need to conduct a similar study, this time on women.

He theorizes that the findings for women might "not differ qualitatively, but we want to see the net health-benefit ratio for aspirin and heart attacks."

Instructor in Medicine Joann E. Manson '75, who is also working on the Women's Health Study with Hennekens, ran a survey of aspirin effects on women in 1980.

But Manson's experiment lacked the formality of Hennekens's study of men and was consequently less conclusive, she says.

Manson had tracked the health of 87,000 nurses for six years, some of whom used aspirin on a weekly basis and some of whom did not.

When the health of both groups were compared, the findings suggested that women over 50 who used one to six aspirin per week had reduced the risks of having a first heart attack by over 30 percent.

The study did not have strong validity for procedural reasons, says Manson. Since it only was a survey, it lacked formality and control of biases. "We need a randomized trial in an experimental study to provide conclusive evidence," Manson says.

Manson adds that it was uncertain whether the results of the new study would agree with her previous findings. "It's hard to say. But we expect some benefit to prevent heart attacks," she says.

Despite the seemingly positive relationship between aspirin use and reduced heart attacks, Manson warns people not to jump on the bandwagon too hastily. "No one should take aspirin regularly without consulting a physician," she says.