The incidence of stroke has declined in recent years, but only in men.

Researchers studied stroke incidence in four periods from 1993 to 2010 in five counties in Ohio and Kentucky. There were 7,710 strokes all together, 57.2 percent of them in women.

After adjusting for age and race, they found that stroke incidence in men had decreased to 192 per hundred thousand men in 2010, down from 263 in 1993–94. But for women the incidence was 198 per hundred thousand in 2010, down from 217 in 1993–94, a statistically insignificant change. The study is in Neurology.

Most of the difference was in ischemic stroke, the most common cause, resulting from a blocked blood vessel supplying blood to the brain.

No one knows why there has been no improvement in women, but the lead author, Dr. Tracy E. Madsen, an assistant professor of emergency medicine at Brown, said that some risk factors have a stronger effect in women than in men. Risk factors for stroke include high blood pressure, heart disease, diabetes and smoking.