Gradient and Acceleration of Decline in Physical and Cognitive Functions in Older Adults: A Disparity Analysis

Background Substantive previous work has shown that both gait speed and global cognition decline as people age. Rates of their decline, as opposed to cross-sectional measurements, could be more informative of future functional status and other clinical outcomes because they more accurately represent deteriorating systems. Additionally, understanding the sex and racial disparity in the speed of deterioration, if any, is also important as ethnic minorities are at an increased risk of mobility disability and dementia. Method Data from 2 large longitudinal intervention studies were integrated. Rates of decline were derived from individual-level measures of gait speed of 400-m walk and scores on the Modified Mini Mental State Examination (3MSE). We also assessed age-associated declines and accelerations in changes across the ages represented in the studies (age range 53–90). Results The mean rate of decline in 400-m gait speed across individuals was 0.03 m/s per year, and multivariable analysis showed a significant acceleration in decline of −0.0013 m/s/y2 (p < .001). Both race and sex moderated the rate of decline. For global cognition, the mean rate of decline was 0.05 of a point per year on the 3MSE scale, and acceleration in the rate of decline was significant (−0.017 point/y2, p < .001), but neither sex nor race moderated the decline. Conclusion Rate of decline in physical but not cognitive function appears moderated by sex and race. This finding, as well as rates and accelerations of decline estimated herein, could inform future intervention studies. Clinical Trials Registration Number NCT00017953 (Look AHEAD); NCT01410097 (Look AHEAD ancillary); NCT00116194 (LIFE).