Association of Neurocognitive and Physical Function With Gait Speed in Midlife

Importance Gait speed is a well-known indicator of risk of functional decline and mortality in older adults, but little is known about the factors associated with gait speed earlier in life. Objectives To test the hypothesis that slow gait speed reflects accelerated biological aging at midlife, as well as poor neurocognitive functioning in childhood and cognitive decline from childhood to midlife. Design, Setting, and Participants This cohort study uses data from the Dunedin Multidisciplinary Health and Development Study, a population-based study of a representative 1972 to 1973 birth cohort in New Zealand that observed participants to age 45 years (until April 2019). Data analysis was performed from April to June 2019. Exposures Childhood neurocognitive functions and accelerated aging, brain structure, and concurrent physical and cognitive functions in adulthood. Main Outcomes and Measures Gait speed at age 45 years, measured under 3 walking conditions: usual, dual task, and maximum gait speeds. Results Of the 1037 original participants (91% of eligible births; 535 [51.6%] male), 997 were alive at age 45 years, of whom 904 (90.7%) had gait speed measured (455 [50.3%] male; 93% white). The mean (SD) gait speeds were 1.30 (0.17) m/s for usual gait, 1.16 (0.23) m/s for dual task gait, and 1.99 (0.29) m/s for maximum gait. Adults with more physical limitations (standardized regression coefficient [β], −0.27; 95% CI, −0.34 to −0.21;P  Conclusions and Relevance Adults’ gait speed is associated with more than geriatric functional status; it is also associated with midlife aging and lifelong brain health.