Background and PurposeChange toward Western lifestyles, particularly during the high economic growth period (approximately 1960 to 1975), dynamically altered stroke frequency and the distribution of risk factors in the Japanese. We reexamined their association after this environmental change by a cohort study.MethodsThe cohort (2302 subjects) comprised residents aged 40 years or older of the Akadani-Ijimino district in Shibata City, Niigata Prefecture, Japan, who were followed up from 1977 for 15.5 years.ResultsCrude incidence rates per 1000 person-years for all strokes were 5.22 for men and 4.36 for women (3.02 and 2.18 for cerebral infarction, 0.65 and 1.06 for intracerebral hemorrhage, and 0.41 and 0.34 for subarachnoid hemorrhage, respectively). Multivariate analyses performed with the Cox proportional hazard model revealed these risk factors to be independently significant: for cerebral infarction in men, age, blood pressure, atrial fibrillation, albuminuria, funduscopic abnormality, and current smoking; for cerebral infarction in women, age, atrial fibrillation, and history of ischemic heart disease; for intracerebral hemorrhage in men, age and funduscopic abnormality; for intracerebral hemorrhage in women, age, blood pressure, and light physical activity; for all strokes in men, age, blood pressure, atrial fibrillation, albuminuria, funduscopic abnormality, current smoking, and heavy physical activity; and for all strokes in women, age, atrial fibrillation, and light physical activity.ConclusionsMost traditional risk factors, including blood pressure and its related organ diseases, were confirmed, but serum total cholesterol had almost no effect. Physical activity had both negative and positive effects on stroke risk. In these findings, however, some differences related to sex were also observed. (Stroke. 1997;28:45-52.)