P1–257: The association between acculturation to Western society and decreased risk for incident Alzheimer's disease is due to education and income differences in elderly Japanese Americans: The Kame Project

Cultural factors may influence AD risk. To determine whether acculturation to Western society is associated with incident AD in a population–based study of elderly Japanese–Americans in King County, Washington. From a target population of 3,045 Japanese–American residents age 65 or older, 1,985 were enrolled in the Kame Project. Of these, 1,616 were free of dementia or Parkinson's disease at baseline, had acculturation data, and had at least one follow–up visit. Acculturation was assessed using 36 items on childhood exposures to Japan, adult contact with Japan, Japanese language use, and cultural preferences. Subjects were evaluated at baseline and every two years with the Cognitive Abilities Screening Instrument. Subjects with low scores (<87/100) were further evaluated with complete physical, neuropsychological, and neuroimaging exams. AD status (probable or possible) was determined by NINCDS–ADRDA criteria. We used item response theory to generate acculturation scores, which were divided into quartiles for analysis. Since results for the bottom two and top two quartiles were similar, we combined subjects into low and high acculturation categories. We used Cox proportional hazards regression to determine the relative hazard associated with higher acculturation scores (being more “Western”). We evaluated the following confounding factors: age, education, income, history of stroke or transient ischemic attack, BMI, smoking history, family history of AD or dementia, presence of an ApoE e4 allele, diabetes, and hypertension. Only income and education were retained in the final model. High levels of acculturation were associated with younger age, 2 generation immigrants, more education, more income, and English language testing. There were 78 incident cases of probable and possible AD. The hazard ratio for AD associated with higher acculturation scores was 0.60 (95% CI: 0.39, 0.94), p=0.027). When income and education were included in the model, the adjusted hazard ratio for AD was 0.82 (95% CI: 0.50, 1.35, p=0.44). These results suggest that the effects of Western culture on AD risk are difficult to disentangle from the effects of income and education. Further efforts are needed to examine the complicated relations between culture and AD risk.