Cross-Cohorts Changes in Physical and Cognitive Functions of Oldest-Old Aged 80-105 in China

Yi Zeng, Duke University and Peking University
Qiushi Feng, National University of Singapore
Qihua Tan, University of Southern Denmark
Kaare Christensen, University of Southern Denmark and Odense University Hospital
James W. Vaupel, Max Planck Institute for Demographic Research and Max Planck Odense Center

This study compares three groups of cohorts born 10 years apart and aged 80-89, 90-99 and 100-105 at interview, using data from Chinese Longitudinal Healthy Longevity Surveys. We found that death rates at oldest-old ages among later cohorts was substantially reduced, compared to cohorts born 10-years earlier; later cohorts had significantly reduced impairment in activities of daily living(ADL) than did cohort born 10 years earlier. We discovered that cognitive functional scores and objective physical performance test scores(stand-up from a chair, pick-up a book from floor, turning around 3600) were all significantly worse in later cohorts, compared to the cohorts born 10 years earlier. Three factors may explain our findings: (1) the mixed effects of the two opposing processes of the success-of-success and failure-of-success when human life span is prolonging; (2) Differences in disability measurements of ADL and objective physical performance tests; (3) Cross-cohorts differences in educational levels and childhood conditions.