Diabetes and Hypertension (Syndrome X) as an Increasing Risk Factor for Cerebrovascular Aging in Japan

Recently, there has been an increased incidence of diabetes mellitus in Japan, where the rate of stroke is high. We reviewed the risk factors of stroke with special reference to "Syndrome X." We reviewed a population-based cohort from 1989 through 1991 that consisted of 7,456 subjects over the age of 35 at Akita, a stroke-prevalent rural district in the northeastern part of Japan known to have the shortest longevity and the highest alcohol consumption in the country. Baseline data were obtained by a questionnaire, physical exams, and blood serum tests. Physical characteristics were similar to national norms, although the proportion of heavy (ex-)drinkers was higher (72.5% for male; 12.0% for female). The prevalence of diabetes mellitus, hypertension, and Syndrome X (defined as diabetes mellitus plus hypertension) was 3.0%, 47.0%, and 1.9%. Observed prevalence of Syndrome X was higher than the expected value. The tendency to disease-clustering was strong in young females. The risk factors of Syndrome X were high body mass index (BMI); a family history of diabetes, hypertension or Syndrome X; regular drinking; high serum GOT; and less walking activity (odds ratio: 1.15, 3.91, 1.62, 4.76, 1.35, 3.97, and 1.21). Stressful occupational environment, feelings of daily stress, a tendency to get angry, and snoring also increased risk of Syndrome X. By 1995,129 stroke cases were observed in the cohort; 123 cases were the first episode. Diabetes mellitus, hypertension, Syndrome X, high BMI, high serum GOT, and less walking activity were associated with significantly higher relative risks for stroke (odds ratio: 2.87, 3.78, 7.42, 1.07, 4.00, and 1.28). Intake of salty foods and hypercholesterolemia were not associated with a higher incidence. The population-attributable risks of stroke related to diabetes mellitus, hypertension, Syndrome X, and high serum GOT were 5.2%, 56.7%, 10.6%, and 7.8%. Syndrome X proved to have the highest relative risk of stroke. Important and controllable risk factors of Syndrome X and stroke were habitual alcohol intake with high serum GOT and less walking activity. Genetic factors were also presumably important to the prevention of Syndrome X. These factors must be considered in strategies aimed at preventing cerebrovascular aging.