Researchers also found racial differences in stroke incidence. For blacks, the incidence of strokes among those over age 85 dropped significantly by 2005. For whites, the incidence decreased significantly starting at age 65 by 2005.

In both races, the incidence rates for strokes in 20 to 45 year olds increased, although the increase was only statistically significant among whites, doubling from 12 per 100,000 people to 25 per 100,000.

Kissela said it's hard to know with certainty what is driving this change, but speculated the increased prevalence of diabetes, hypertension and obesity is a major contributor.

"As physicians, we need to look for these potent risk factors even in young people," he said. "Stroke is a life-changing, devastating disease. It can affect young people, and we hope these data will serve as a wake-up call.

"From a public health standpoint, we need to do our best to prevent stroke at any age and monitor for stroke and stroke risk factors in all patients."

Source: American Heart Association