Body mass index trajectories and functional decline in older adults: Three-City Dijon cohort study.

Obesity, whose prevalence is increasing, is associated with poor functional status at older ages. However, much of this evidence is cross-sectional with little known about longitudinal associations. We examined associations of body mass index (BMI), and change in BMI, with change in objective [walking speed (WS)] and self-reported (disability) measures of motor decline. Analyses included participants (65-85 years) from the Dijon center of the Three-City study (France) with up to five WS (N = 4007) and six disability assessments (N = 4478) over 11 years. Data were analyzed using regression models for repeated measures. Mean baseline WS was 153 cm/s. Compared to normal weight persons, obese participants at baseline walked slower and reported more disability; they also experienced 45% faster WS decline (-18.63 vs. -12.85 cm/s/10 years, P = 0.002). Participants who lost or gained weight had 47% (-18.85 cm/s/10 years, P < 0.001) and 33% (-17.08 cm/s/10 years, P = 0.002) respectively greater WS decline than participants in the normal BMI change category. 24% of participants reported disability at least once during the follow-up, those who lost or gained weight had a 1.63 and 1.34 respectively higher odds of disability than participants in the normal BMI change category (P = 0.001). Associations remained after adjustment for covariates. In conclusion, obesity is associated with worse motor performances, a higher risk of disability, and faster motor decline. Our results underline the interest of repeated BMI and motor assessments to identify those at higher risk of disability.