Cognitive Performance Among Older Persons in Japan and the United States

OBJECTIVE To compare cognitive performance among Japanese and American persons, aged 68 years and older, using two nationally representative studies and to examine whether differences can be explained by differences in the distribution of risk factors or in their association with cognitive performance. DESIGN Nationally representative studies with harmonized collection of data on cognitive functioning. SETTING Nihon University Japanese Longitudinal Study of Aging and the US Health and Retirement Study. PARTICIPANTS A total of 1953 Japanese adults and 2959 US adults, aged 68 years or older. MEASUREMENTS Episodic memory and arithmetic working memory are measured using immediate and delayed word recall and serial 7s. RESULTS Americans have higher scores on episodic memory than Japanese people (0.72 points on a 20-point scale); however, when education is controlled, American and Japanese people did not differ. Level of working memory was higher in Japan (0.36 on a 5-point scale) than in the United States, and the effect of education on working memory was stronger among Americans than Japanese people. There are no differences over the age of 85 years. CONCLUSION Even with large differences in educational attainment and a strong effect of education on cognitive functioning, the overall differences in cognitive functioning between the United States and Japan are modest. Differences in health appear to have little effect on national differences in cognition.