Frequency and Classification of Cerebral Infarctions in Nursing Homes over a 17-Year Period in Shimane Prefecture, Japan

Abstract

Background: Several recent epidemiological investigations have shown that the rate of vascular dementia (VD) has decreased and the rate of senile dementia of the Alzheimer type has increased in Japan. In our previous neuropathological examination, such a trend but no significant differences were shown in nursing home residents in Shimane Prefecture, Japan. Objective: The aim of this study was to clarify whether or not the frequency of cerebral infarctions (CI) and the ratio of CI [large infarction type (LI) and small multiple infarction (MI)] types changed between the first half of this study and the second half, corresponding to the decreasing trend of the rate of VD. Methods: Three hundred and ten aged nursing home residents (146 men and 164 women) were evaluated neuropathologically in Shimane prefecture, Japan. All subjects died between 1976 and 1992. The average age ± standard deviation at death was 79.1 ± 8.7 years for men, 83.4 ± 7.8 for women, and 81.4 ± 8.5 overall. They were placed into the first or second study group and compared. Results: (1) The incidence of hypertension (HT) decreased significantly from the first half of the study to the second half in both men and women. (2) The frequencies of CI and CI with HT were not significantly different between the first and second half (both men and women). (3) There was a decreasing trend in the ratio of LI to MI from the first to the second period in men. Conclusion: There may be no effect of the incidence of HT on CI frequency and some effects on CI types. The incidence of CI in total lifespan (both men and women) has not changed in our study. The recent decreasing trend in LI in men may have contributed to the decreasing tendency in the prevalence of vascular dementia.