About 700,000 strokes occur each year in the United States, approximately one-fourth of which are fatal and an additional one-fourth of which leave patients permanently disabled, according to background information in the article. There are two main types of stroke: ischemic, the more common type, in which a blocked artery causes a lack of blood flow to the brain; and hemorrhagic, which occurs when a ruptured blood vessel causes blood to leak into the brain. Several individual risk factors, including smoking, exercise and body mass index (BMI), have been linked to stroke. However, in contrast to studies assessing risk for heart disease and diabetes, researchers have not previously examined how the combination of these behaviors may contribute to stroke.

Tobias Kurth, M.D., Sc.D., Brigham and Women's Hospital and Harvard School of Public Health, Boston, and colleagues studied the association between healthy lifestyles and stroke risk in 37,636 women age 45 years or older. At the beginning of the study, in 1993, the women answered questions about their smoking habits, alcohol consumption, diet, exercise routine and body mass index. From their responses, the researchers gave each woman a health index score that ranged from zero to 20, with a higher score indicating a healthier lifestyle. Healthy behavior was defined as never smoking, consuming four to 10.5 alcoholic drinks per week, exercising four or more times per week, having a body mass index of less than 22 and maintaining a healthy diet. This included consuming high levels of cereal fiber, folate and omega-3 fatty acids, a high ratio of polyunsaturated to saturated fat and low levels of trans fat and glycemic load.

During an average of 10 years of follow-up, 450 women had strokes; 356 were ischemic, 90 were hemorrhagic and four were undefined. The 4.7 percent of women with 17 to 20 health index points had a significantly lower risk of stroke overall and of ischemic stroke specifically than women with zero to four health index points. This association remained significant even when the researchers considered some of the common consequences of unhealthy lifestyles, including high blood pressure, diabetes and high cholesterol.

"In this large prospective cohort of apparently healthy women, a healthy lifestyle was associated with a substantial and statistically significant reduction in the risk of total and ischemic stroke with no apparent benefit in the incidence of hemorrhagic stroke," the authors conclude. "Our findings show the importance of healthy behaviors in the prevention of total and ischemic stroke."

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