Body Composition, Serum S100beta and Leptin Levels in Older Adults

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INTRODUCTION: Older adults are the least physically active segment of the American population (Nelson et al 2007). It is well established that excess body fat is associated with hypertension, type 2 diabetes, stroke, CAD, and hyperlipidemia. (United Stated Department of Health and Human Services. Physical activity and health: a report of the Surgeon General, 1996.) Recent work also indicates that obesity is associated with adverse changes to the brain and cognitive function, though the mechanisms for this remain unclear. A likely mechanism involves disruption in biomarkers that are associated both with obesity and neurocognitive dysfunction. Elevated S100B levels reflect blood brain barrier (BBB) dysfunction and conditions comorbid to obesity show BBB dysfunction (e.g. hypertension, Type 2 diabetes; Kanner et al., 2003). Leptin, a circulating biomarker important for neuronal function is also associated with obesity in younger adults (Coll et al 2007). Their association in older adults is unknown. PURPOSE: To examine the relationship between body composition and serum S100B and Leptin levels in older adults. METHODS: Thirty-five community dwelling older adults (54% female, average age 73.7 ± 6.6), underwent fasting blood draws. Body composition was assessed through skinfold measurements, BMI and waist to hip ratio. RESULTS: Partial correlations adjusting for physical activity levels indicated a significant association between S100β and skinfold measurements (r= 0.311, p= 0.04) and was nearly correlated with BMI (r=0.291, p= 0.053). Consistent with findings in younger adults, skinfold measurements were also associated with leptin levels (r= 0.717 p= 0.000) after adjusting for age, gender, insulin and physical activity levels. Body mass index was associated with leptin (r= 0.509, p= 0.005). CONCLUSION: In the present study, increased body fat is associated with greater levels of S100B and leptin in healthy older adults. Such findings implicate these biomarkers in the adverse neurocognitive outcome of obesity. However, prospective studies and those involving neuroimaging are needed to confirm and extend these results.