PREVALENCE OF DEMENTIA AND ITS SUBTYPES IN THE JAPANESE-AMERICAN POPULATION OF KING COUNTY, WASHINGTON-STATE - THE KAME PROJECT

Studies of Asian populations generally have reported prevalence rates for dementia similar to those of predominantly Caucasian populations, but relative prevalence rates of Alzheimer's disease and vascular deme ntia have differed. Between May 1, 1992 and May 1, 1994, the prevalenc e rates of dementia, Alzheimer's disease, and vascular dementia were e xamined in the Japanese American population aged over 65 years in King County, Washington State. A total of 3,045 eligible individuals were identified in a census of persons who were of at least 50% Japanese he ritage. Of 1,985 persons who participated in the baseline examination, 382 individuals of 450 sampled from all cognitive performance strata received a diagnostic evaluation. A total of 107 cases with a Clinical Dementia Rating (CDR) of greater than or equal to 1 met criteria for dementia according to the Diagnostic and Statistical Manual, 3rd editi on, revised (DSM-III-R); 58 of these cases were diagnosed with Alzheim er's disease and 24 with multi-infarct dementia. The estimated prevale nce rate for all dementias was 6.3% (95% confidence interval 5.9-6.8). Prevalence rates for dementia increased continuously with age and wer e 30%, 50%, and 74% for participants aged 85-89, 90-94, and greater th an or equal to 95 years, respectively; for Alzheimer's disease, preval ence rates were 14% 36%, and 58% for these three age groups. Rates for Alzheimer's disease were generally higher among women; for multi-infa rct dementia, rates for mpn-and women were similar, In the institution al population, the prevalence rate was 66%, and in the community, 2.9% . Persons with lower education had higher overall rates of dementia th an those with higher education, but this tendency became weak and inco nsistent when rates were age-stratified. The prevalence of dementia in this geographically defined population of Japanese Americans was some what higher than prevalence rates reported from Japan, and the distrib ution of dementia subtypes more closely resembled that found in Caucas ian populations in North American and Europe than previously reported in Asian populations.