Background: leptin resistance, which may develop during the ageing process, stimulates the production of pro-inflammatory cytokines and insulin resistance that could impair the muscle function. However, the role of leptin on physical functioning among older adults has not yet been elucidated.
Objective: to examine the association between serum leptin levels and physical function impairment in older adults.
Design and setting: prospective study of 1,556 individuals 60 years and older from the Seniors-ENRICA cohort, who were free of physical function limitation at baseline.
Main outcome measure: serum leptin was measured in 2008-10, and incident functional limitation was assessed through 2012. Self-reported limitations in agility and mobility were assessed with the Rosow and Breslau scale, limitation in the lower extremity function was measured with the Short Physical Performance Battery, and impairment in the overall physical performance with the physical component summary of the SF-12.
Results: after adjustment for potential confounders and compared to individuals in the lowest quartile of leptin concentration, those in the highest quartile showed increased risk of impaired physical function; the odds ratio (95% confidence interval) and P-trend was: 1.95 (1.11-3.43), P = 0.006 for self-reported impaired mobility; 1.76 (1.08-2.87), P = 0.02 for self-reported impaired agility; 1.48 (1.02-2.15), P = 0.04 for limitation in the lower extremity function; and 1.97 (1.20-3.22), P = 0.01, for decreased overall physical performance. These associations were only modestly explained by C-reactive protein and insulin resistance. Moreover, the associations held across groups with varying health status and were independent of estimated total body fat.
Conclusions: higher leptin concentration was associated with increased risk of impaired physical function. Preserving metabolic function during the old age could help delaying physical function decline.
Keywords: biological markers; leptin; mobility limitation; older people; physical fitness; prospective studies.
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