Japanese Americans in King County, WA: The Kame Project

Objectives. The prevalence of Alzheimer's disease in studies of Japanese show generally lower rates when compared with those of Caucasians. We hypothesized that among a cohort of Japanese Americans lifestyle differences would act to modify progression of the Alzheimer pathologic process over many years, resulting in a slower cognitive decline among persons whose lifestyle is more characteristically Japanese. Methods. One thousand, eight hundred and thirty-six nondemented persons were screened with the Cognitive Abilities Screening Instrument (CASI) at baseline, and 1,604 were rescreened 2 years later. Baseline questions included migration status, exposure to Japanese culture in early life and maintenance of such culture in adulthood, and other risk factors. Cognitive de-cline was defined as a 2-year loss of>5.15 points/100 on CASI. Results. In multivariable logistic regression, variables relating to reading, writing, and speaking Japanese, being born or hav-ing lived in Japan in early life, and having friends who are only/mostly Japanese were inversely associated with cognitive de-cline (odds ratios ranged between 0.28 and 0.64, withp<.05). Two factors emerged in a factor analysis of these variables. The strongest explained 49 % of the variance for acculturation and loaded heavily on knowledge of the Japanese language and hav-ing spent one's early years in Japan. When this factor was dichotomized into the top 20th percentile, it predicted cognitive de-cline with an odds ratio of 0.12 (95 % CI 0.03-0.49). Discussion. These results show that a Japanese lifestyle may decrease the risk of expressing cognitive decline over a 2-yea