When it comes to stroke prevalence, it appears that the gender gap is widening. Women between the ages of 35 and 64 are almost three times more likely to have a stroke than men in the same age group, says a new report from a researcher at the University of Southern California's Keck School of Medicine.

Meanwhile, separate new research shows that women who don't receive a clot-busting drug after a stroke fare worse than men who aren't treated. The study was published earlier this month in a print issue of Neurology, the medical journal of the American Academy of Neurology.

The findings of the gender-gap stroke study were presented last month at an American Stroke Association international stroke conference in San Antonio, Texas.

"Although midlife women's blood pressure and lipid profiles are better than men's, they have significantly higher rates of abdominal obesity, which may be driving this trend" of having increasingly more strokes than men, says Dr. Amytis Towfighi, assistant professor of neurology at the Keck School of Medicine, and the principal investigator of the study.

The investigators first reported on the evolving gender difference in rates of midlife stroke three years ago. An analysis of stroke prevalence in the U.S. from 1999 to 2004 found that women between 45 and 54 years of age were twice as likely as men to report having had a stroke.

In the latest study, the researchers analyzed data from the National Health and Nutrition Examination Surveys 2005-2006 (NHANES), a cross-sectional sample of more than 10,000 adults in the U.S. The data included nearly 2,200 men and women between 35 and 64 years of age.

The investigators found that women in the age group were almost three times more likely than men of the same age to report having had a stroke—2.9 percent versus 1.07 percent.

A comparison of vascular risk factors showed that women had better than average blood pressure, homocysteine (amino acid in the blood), and triglyceride levels than men, but women were more likely to have abdominal obesity, at 61.9 percent versus 50 percent. Abdominal obesity is a known predictor of stroke in women and may be a key factor in the midlife stroke surge in women, Towfighi says.

Independent stroke risk factors for women also included elevated homocysteine levels, history of heart attack, and diabetes mellitus.

"Further investigation is needed to understand this apparently evolving sex disparity in midlife stroke prevalence," Towfighi says. "Better management of stroke risk factors such as coronary artery disease, diabetes, and abdominal obesity may help mitigate this worsening trend in women's health."

The other stroke-related study, conducted in Canada, found that women who didn't receive a clot-busting drug known as tissue plasminogen activator (tPA) were 12 percent less likely than men to have a good outcome six months later. Fifty-eight percent of the women had what they characterized as a good outcome, compared with 70 percent of men. However, women who were treated with these medications fared about the same as men who took the clot-buster drug.

"Women need to be treated for stroke as soon as possible," says study author Dr. Michael D. Hill, with the University of Calgary, in Alberta, Canada. "We found that women who weren't treated had a worse quality of life after stroke than men. However, the good news is that women who were treated responded just as well as men to the treatment."

For that study, scientists examined information from a stroke database on more than 2,000 people who had experienced a stroke. Of those, 232 were treated with tPA and 44 percent were women. Men and women were separately placed in groups based on whether they received tPA within three hours after their stroke. After six months, the people were interviewed by phone about their ability to function and quality of life.

"There could be many reasons why women who weren't treated with the clot-busting drug fared worse than men, including biological reasons," Hill says. "One social reason may be that more than 30 percent of women were widowed compared to 7 percent of men at the time of stroke, and therefore did not have a spouse who could act as a caregiver.

Also, post-stroke depression is more common in women than in men, which slows down recovery."

The study was supported by the Canadian Stroke Network, one of Canada's Networks of Centers of Excellence program, and the Ontario Ministry of Health and Long-Term Care.

The American Academy of Neurology, an association of more than 22,000 neurologists and neuroscience professionals, promotes high-quality, patient-centered neurologic care. A neurologist is a doctor with specialized training in diagnosing, treating, and managing disorders of the brain and nervous system such as multiple sclerosis, restless legs syndrome, Alzheimer's disease, narcolepsy, and stroke.