Prevalence of dementia in a Japanese elderly population.

The geriatric community study was conducted by the Aichi Prefecture (Japan) Project. The psychiatric epidemiological survey was conducted using a stratified random sampling method. 3106 community residents over the age of 65 years, randomly selected from the whole Aichi Prefecture of Japan, were interviewed; 476 had suspected dementia. The second interviews and the neurologic examinations were carried out by psychiatrists. The prevalence of dementia was estimated to be 5.8% (moderate and severe, 2.2%; mild 3.6%) of the aged population in the community. Cerebrovascular dementia (CVD) or multi-infarct dementia (MID) was found in 2.8%, senile dementia of the Alzheimer type (SDAT) in 2.4%, and dementia due to other causes in 0.6%. CVD (MID) was diagnosed more frequently in men, and SDAT in women.