American Journal of Epidemiology Copyright O 1996 by The Johns Hopkins University School of Hygiene and Public Health All rights reserved Vol. 144, No 8 Printed In U S.A Prevalence of Dementia and Its Subtypes in the Japanese American Population of King County, Washington State The Kame Project A. B. Graves, 1 E. B. Larson, 2 - 3 S. D. Edland 45 J. D. Bowen, 6 W. C. McCormick, 23 S. M. McCurry, 7 M. M. Rice, 8 A. Wenzlow, 9 and J. M. Uomoto 10 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 dementia have differed. Between May 1,1992 and May 1,1994, the prevalence rates of dementia, Alzheimer's disease, and vascular dementia were examined 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 heritage. 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 >1 met crrtena for dementia according to the Diagnostic and Statistical Manual, 3rd edition, revised (DSM-III-R); 58 of these cases were diagnosed with Alzheimer's disease and 24 with multi-infarct dementia. The estimated prevalence rate for all dementias was 6.3% (95% confidence interval 5.9-6.8). Prevalence rates for dementia increased continuously with age and were 30%, 50%, and 74% for participants aged 85-89, 90-94, and &95 years, respectively; for Alzheimer's disease, prevalence rates were 14%, 36%, and 58% for these three age groups. Rates for Alzheimer's disease were generally higher among women; for multi-infarct dementia, rates for men and women were similar. In the institutional population, the prevalence rate was 66%, and in the community, 2.9%. Persons with lower education had higher overall rates of dementia than those with higher education, but this tendency became weak and inconsistent when rates were age-stratified. The prevalence of dementia in this geographically defined population of Japanese Americans was somewhat higher than prevalence rates reported from Japan, and the distribution of dementia subtypes more closely resembled that found in Caucasian populations in North America and Europe than previously reported in Asian populations. Am J Epidemiol 1996;144:760-71. Alzheimer's disease; cross-cultural comparison; dementia; dementia, multi-infarct; prevalence Despite similar overall prevalence rates for demen- tia in North American, European, and Asian popula- tions (1-8), the relative proportions attributed to Alz- heimer's disease and vascular causes differ markedly. In most Asian studies, between 30 to 60 percent of dementia cases have been ascribed to vascular causes (6, 9-11) and approximately half as many to Alzhei- mer's disease (12, 13). In most Western studies of predominantly Caucasian populations, the reverse is true, with at least 50-70 percent of the total dementia rate attributed to Alzheimer's disease and only 12-20 percent to vascular causes. Exceptions to this general Received for publication September 21, 1995, and accepted for publication May 8, 1996. Abbreviations: CASI, Cognitive Abilities Screening Instrument; CDR, Clinical Dementia Rating; CERAD, Consortium to Establish a Registry for Alzheimer's disease; Cl, confidence interval; DSM-III-R, Diagnostic and Statistical Manual, 3rd edition, revised; K3CODE, Informant Questionnaire on Cognitive Decline in the Elderty; NART, New Adult Reading Test; OR, odds ratio; SD, standard deviation. 1 Department of Epidemiology and Biostatistjcs, University of South Florida, Tampa, Fl_ 2 Department of Medicine, University of Washington, Seattle, WA 3 Department of Health Services, University of Washington, Seattle, WA 4 Department of Environmental Health, University of Washington, Seattle, WA. 5 Department of Biostatistics, University of Washington, Seattle, WA 8 Department of Medicine (Division of Neurology), University of Washington, Seattle, WA 7 Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA 8 Department of Epidemiology, University of Washington, Seat- tle, WA 9 Battelle Centers for Public Health Research and Evaluation, Seattle, WA 10 The Shepherd Center, Acquired Brain Injury Program, Atlanta, GA Reprint requests to Dr. Amy B. Graves, Dept of Epidemiology and Biostatistics, University of South Florida, 13201 Bruce B. Downs Blvd., Tampa, FL 33612-3805. 760 by guest on July 21, 2011 aje.oxfordjournals.org Downloaded from