Epidemiological studies on Aging of Population in Yamanashi Prefecture

Abstract

Studies were carried out on the annual rise and fall and geographical distribution of the index showing an increase in the number of aged people in the population of Yamanashi Prefecture.
Annual changes were examined in the proportion and index of age-groups of the population in and after 1950. The proportion has been decreasing for the population of 0 to 14 years and increasing for the population of 15 to 64 years and that of 65 years and over every year. The index has been increasing for the index of senile population (population of 65 years and over divided by population of 15 to 64 years) and that of senile generation (population of 65 years and over divided by population of 0 to 14 years) every year. The latter two index in 1975 were two to three times as large as those in and before 1950.
The proportion and index of age-groups of population are rather high in Yamanashi Prefecture, as compared with those in other prefectures of the country.
The proportion of people more than 65 years old (population of people more than 65 years old divided by population), the rate of long-living persons (population of people more than 70 years old divided by population), the ratio of the aged (population of people more than 70 years old divided by population of people more than 65 years old) and longevity (population of people more than 75 years old divided by population of people more than 65 years old) have been increasing for both males and females since 1950. When they were compared between the whole country and Yamanashi Prefecture, every one of them was higher in this prefecture than in the whole country.
A group of cities, towns, and villages where the index of senile population and that of senile generation were rather high in 1955 showed also a marked increase in those indices in 1965 and 1975. On the other hand, there were differences in the annual distribution of the ratio of aged and ratio of longevity among such cities, towns, and villages.
The index of senile population, the index of senile generation, the rate of long-living persons and longevity were all low in cities and suburban towns and villages in 1975. Moreover, the index of senile population and the index of senile generation were low in cities, towns, and villages in the eastern parts of Yamanashi Prefecture. The rate of long-living people and longevity were rather high in towns and villages in the central and southern parts of the prefecture.