Aging & Society: Eighth Interdisciplinary Conference

Abstract

Taiwan is one of the fastest aging countries, and Japan has the highest proportion of older adults in the world. Although longitudinal patterns of change for cognitive function are well-documented in the literature, only a scarce amount of research examines those patterns with age trajectories and conduct cross-national comparison. Additionally, existing studies are limited by their modeling approach, which generally delineates long-term change by time (year) but not by age. Complicated by the heterogeneous age constitutions of the older populations at baseline and over time, the existing approach generally cannot clarify if changes in the long-term observations overtime were due to age or cohort effect. This study using two comparable nationally representative datasets in Taiwan and Japan with participants from the Taiwan Longitudinal Study on Aging (TLSA) and the National Survey of the Japanese Elderly (NSJE). Hierarchical linear model was used to clarify the longitudinal changes in cognitive function. Age and cohort model tested the cognitive impairment trajectories for older adults assessed with Short Portable Mental State Questionnaire (SPMSQ). Results show that the Japanese elderly seem to have better cognitive function than Taiwanese elderly during aging, and the elderly in Taiwan have significantly decreased cognitive function scores with age, whereas Japan does not. The effects of cohorts also affect the cognitive function of the elderly in Taiwan and Japan. For example, among the elderly people after the age of eighty-five, Taiwan dropped an average of about four points on average while Japan only dropped about 2.5 points.