GEROSCIENCE BLOOD-BASED BIOMARKER INDICES AND PHYSICAL PERFORMANCE IN OLDER ADULTS

Abstract

Abstract Dysregulation in cellular and molecular aging biomarkers are hypothesized to contribute to worse physical performance. We examined associations between blood-based geroscience biomarker indices and physical performance in 414 older adults (77.4±4.4 years; 69% female). Physical performance measures included the expanded SPPB, 4m and 400m walk, and grip strength. Serum IL-6, CRP, TNFr1, GDF15, and insulin were measured and three biomarker indices created: 1) a quintile index calculated by summing quintile scores for each of the biomarkers; 2) a composite z-score calculated using the standardized mean of individual biomarker z-scores; and 3) a principal component analysis (PCA) to identify biomarker factor(s). The quintile index and composite z-score were highly correlated (r=0.94, p< 0.0001). PCA identified two factors: TNFr1 and GDF-15 weighted heavily on Factor 1 and IL6 and CRP weighted heavily on Factor 2. The quintile index and composite z-score were correlated with PCA Factors 1 and 2 (r>0.61, p< 0.0001). Similar standardized beta coefficients were observed for the quintile index, composite z-score, and PCA Factor 1 with 4m and 400m gait speed (all p< 0.0001); every 1 SD higher biomarker index score was associated with ~0.25 SD slower gait speed. For expanded SPPB, higher standardized beta coefficients were observed for the quintile index and composite z-score (~-0.32) than PCA Factors 1 and 2 (~-0.24; all p< 0.0001). Weak associations between all indices and grip strength were observed (p≥0.05). Geroscience biomarker indices that capture inflammation and poor stress response appear to have similar associations with worse physical performance in older adults.