Effects of DHEAS on skeletal muscle over the life span: the InChianti study

Background. It has been suggested that the reduced production of dehydroepiandrosterone sulfate (DHEAS) may be partially responsible for the decline of muscle strength and mass that often occurs with aging. However, this hypothesishas been only tested in small series of normal volunteers, with little consideration for potential confounders. Using datafrom a representative sample of 558 men (20–95 years) we tested the hypothesis that circulating DHEAS is independentlyassociated with muscle strength and mass. Methods. Data are from InCHIANTI, an epidemiological study conducted in the Chianti geographic area (Tuscany, Italy). DHEAS serum levels were related to lower extremity muscle strength assessed by hand-held dynamometry and calf muscle area estimated from quantitative computerized tomography. Confounders included age, anthropometrics, physical activity, smoking, energy and alcohol intake, albumin, lipids, interleukin-6, comorbidity, depressive symptoms, and disability in activities of daily living. Results. In fully adjusted models predicting lower extremity muscle strength and calf muscle area, we found significant age*log DHEAS interactions, suggesting that the relationship between DHEAS levels and muscle parameters differs across the life span. In age- stratified models adjusted for confounders, serum DHEAS was an independent predictor of muscle strength ( p , .02) and mass ( p , .01), but only for men between 60 and 79 years of age. After adjusting these models for serum-free or bioavailable testosterone, results were unchanged. Conclusions. In men aged 60– 79 years, circulating DHEAS is an independent correlate of muscle strength and calf muscle area.