FRIDAY, Feb. 20, 2009 (HealthDay News) -- Experiencing early menopause significantly raises a woman's risk for stroke, new research reveals.
"Women who reached menopause before age 42 had a doubling in the risk of ischemic stroke, compared to all other women," said Dr. Linda Lisabeth, an assistant professor of epidemiology at the University of Michigan School of Public Health and an author of the study. The findings were to be presented Friday at the International Stroke Conference in San Diego.
Ischemic stroke, in which blood vessels clog, is the most common type of stroke in the United States. About 144,000 people a year die from a stroke, according to the American Stroke Association.
Lisabeth and her colleagues followed 1,430 women who participated in the long-running Framingham Heart Study. They had all been stroke-free until age 60 and had gone through natural menopause. According to the women, who reported their own ages at menopause, 56 went through menopause before age 42, 1,299 experienced it from ages 42 to 54, and 75 women experienced menopause at age 55 or older. None had used estrogen before menopause.
The researchers followed the women until they had their first ischemic stroke, died or had completed the 22-year follow-up.
During that time, eight of the 75 late-menopause women had a stroke, 213 in the much larger middle group (age 42 to 54) did, and 13 of 56 of the early-menopause women did.
After adjusting for such factors as age, blood pressure, diabetes, smoking and heart disease, they still found that those who went through early menopause were two times more likely to have had a stroke than were the others.
Where does this fit in the big picture? "Four or five percent of all strokes in women could be attributed to this risk factor," Lisabeth said.
Exactly how to explain the link remains unclear, she said. The lower estrogen levels associated with menopause might play a role, she said, but evidence on whether this is so is conflicting.
Dr. Brian Silver, an assistant professor of neurology at Henry Ford Hospital in Detroit, who led a panel on women and stroke at the conference, said that the finding does not appear to be a fluke and bears attention and more research.
"This is a 100 percent increase, or a doubling" of risk for women who experience menopause before age 42, he said. "It is statistically significant."
Though early menopause occurs in just a small percentage of women, he said, the link should be investigated further. "The study doesn't tell us the mechanism," he said. It would be premature, he added, to advise women who undergo menopause early to take hormone replacement therapy.
For now, the best advice for women who go through menopause early is to modify whatever other risk factors they can, he said. "That means exercise, weight loss, smoking cessation, a balanced diet with plenty of vegetables and fruits, blood pressure control." It's also a good idea for women to have their blood sugar checked and to be sure their cholesterol is at normal levels, he said.
The study is published in the February issue of Stroke.
The American Stroke Association has more on risk factors.