We followed 828 nondemented residents of Hisayama Town, Kyushu, Japan, aged 65 years or older (88.3% of the elderly population) for 7 years starting in 1985 in order to determine the type-specific incidence of dementia and its risk factors in the general Japanese population. Only two subjects were lost to the follow-up, during which period 103 subjects developed dementia. Morphologic examination of the brains of 89 subjects (86.4%) was made by autopsy or CT. We made the initial diagnosis of dementia based on the DSM-III-R criteria, with the diagnoses of vascular dementia (VD) being based on the NINDS-AIREN criteria and Alzheimer's disease (AD) on the NINCDS-ADRDA criteria. The incidence of VD and AD increased with age for both sexes. The age-adjusted total incidence (per 1,000 person-years) of dementia was 19.3 for men and 20.9 for women. The corresponding rates for VD were 12.2 for men and 9.0 for women, and for AD, 5.1 for men and 10.9 for women. Among the VD subjects whose brain morphology we examined, the most frequent type of stroke was multiple lacunar infarcts (42%), but half these subjects lacked a stroke episode in their histories. Multivariate analysis showed that age, prior stroke episodes, systolic blood pressure, and alcohol consumption were significant independent risk factors for the occurrence of VD. In contrast, age and a low score on Hasegawa's dementia scale were significant risk factors for AD, and physical activity was a significant preventive factor for AD.(ABSTRACT TRUNCATED AT 250 WORDS)

We determined the population-based prevalence of diabetes mellitus in members of the Japanese community, Hisayama aged 40-79 years old by a 75-g oral glucose tolerance test. The basic population used to calculate diabetic prevalence was 1,077 men (72.8% of the whole population in the same age range) and 1,413 women (80.8%) including ten diabetic patients on insulin therapy. In addition, we compared the prevalence of history of diabetes which was acquired by interview or questionnaire, between participants and non-participants in the 75-g oral glucose tolerance test, but they were not statistically different. The age-adjusted prevalence of diabetes to world population was 12.7% for men and 8.4% for women, and that of impaired glucose tolerance was 19.6% for men and 18.4% for women. These figures were much higher than those previously reported from several Japanese communities. The results obtained from the present study could reveal true prevalence of diabetes among the Japanese population. In addition, the reasons for the increasing prevalence of diabetes among the recent Japanese population are also discussed.

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To elucidate the risk factors for initiating glucose intolerance, the relevant factors were explored in a cross-sectional survey conducted in a sample population aged 40-79 years old selected from a Japanese community, Hisayama, Japan in 1988. A 75-g oral glucose tolerance test was used to classify 1,073 men (72.5% of the entire population in the same age range) and 1,407 women (80.5%) into normal, impaired glucose tolerance and diabetes mellitus groups. In all age and sex groups with normal glucose tolerance, the sum of fasting and 2-h post-load insulin values varied widely and demonstrated significant positive correlations with triglycerides, body mass index, waist-hip ratio, systolic and diastolic blood pressure, while it negatively correlated to HDL cholesterol (p < 0.05). Insulin resistance was presumed to develop in normal glucose tolerance subjects with hyperinsulinaemia. The sum of the insulin concentrations, triglycerides, body mass index, waist-hip ratio and blood pressure levels was significantly associated with impaired glucose tolerance in all age and sex groups after adjustment for age (p < 0.05) and was also related to diabetes in either all or some age and sex groups, respectively (p < 0.05). It was shown that glucose intolerance in the general population was associated with the factors related to insulin resistance. These cross-sectional data, therefore, support the hypothesis that insulin resistance is the primary defect in the development of glucose intolerance in the Japanese general population. However, a further prospective study is still needed in order to confirm this hypothesis.

Kawano H, Kato I, et al.: Accuracy of diagnosis on death certificates for underlying causes of death in a long-term autopsy-based population study in Hisayama, Japan; with special reference to cardiovascular diseases.