Epidemiological survey of dementia and depression among the aged living in the community in Japan.

The authors surveyed the prevalence of depression and dementia in the elderly in Ohira town in Japan from 1989 to 1990. The total population of this town was 26,712, with 2,778 people aged 65 and above, constituting 10.4% of the total population. The prevalence of dementia (n = 128) was 6.1% and that of major depression (n = 9) was 0.4%, according to the DSM-III-R criteria. The prevalence of a depressive state which did not fulfill the criteria for major depression (n = 55) was 2.4%. The patients with multi-infarct dementia (n = 49) suffered from depression (42.8%) more frequently than those with dementia of the Alzheimer type (11.1%). The rate of depression coexisting with dementia increased with aging, while the rate of depression without dementia did not change in all the age groups.