Study Identifies February-April as Stroke Season

United Press International

The incidence of strokes appears to vary with the season, and the most common form occurs most frequently in the late winter or early spring, a researcher said Tuesday.

In one of the largest studies of its kind, researchers found that strokes caused by arteries becoming blocked from blood clots or fat--known as infarcts--occur most often from February through April.

“We found a very strong variation in the occurrence of strokes by season,” said Eugene Sobel, an epidemiologist who conducted the study at Temple University School of Medicine in Philadelphia.


Using a register of 600,000 residents of the Lehigh Valley in Pennsylvania, the researchers analyzed 1,944 cases from an 18-month period beginning in July, 1982.

No seasonal association was found with less common types of strokes that are caused by hemorrhages, but infarcts occurred at a rate of about 80 a month from February through April, compared to 60 a month at other times of the year.

The researchers had no explanation of why strokes would follow a seasonal pattern, but they found that lesser attacks, known as transient ischemic attacks, considered warning signs that a major stroke is imminent, also seem to occur seasonally.