EPIDEMIOLOGIC AND GENETIC-STUDIES OF DEMENTIA OF THE ALZHEIMER-TYPE IN JAPAN

We carried out two separate epidemiological studies on long-term chang es, 10 years apart, on the prevalence rate of dementia in the elderly by the same method for the same area in Japan. We also performed a gen etic study of patients with dementia of the Alzheimer type (DAT) based on the epidemiological studies. The number of patients with dementia was much larger in 1990 than ill 1980. Especially, the number of mildl y demented patients was significantly larger in 1990 than in 1980. The 35 patients with DAT did not show any mutations of amyloid-beta prote in precursor, presenilin 1 and presenilin 2 genes. The frequency of ap olipoprotein E (apo E) epsilon 4 allele in DAT was significantly highe r than that in control subjects (p < 0.005). This study suggests that the frequency of DAT may increase by aging of the population in the fu ture and we confirm the close association between apoE epsilon 4 allel e and DAT in a community-based study in Japan.