Association between aging-related biomarkers and longitudinal trajectories of intrinsic capacity in older adults

Intrinsic capacity (IC), the composite of physical and mental capacities, declines with age at different rates and patterns between individuals. We aimed to investigate the association between longitudinal IC trajectories and plasma biomarkers of two hallmarks of aging-chronic inflammation and mitochondrial dysfunction-in older adults. From the Multidomain Alzheimer Preventive Trial (MAPT), we included 1271 community-dwelling older people (mean [SD] age = 76.0 [4.3] years) with IC data over four years. Group-based multi-trajectory modeling was performed to identify clusters of the participants with similar longitudinal patterns across four IC domains: cognition, locomotion, psychology, and vitality. Five IC multi-trajectory groups were determined: low in all domains (8.4%), low locomotion (24.6%), low psychological domain (16.7%), robust (i.e., high in all domains except vitality; 28.3%), and robust with high vitality (22.0%). Compared to the best trajectory group (i.e., robust with high vitality), elevated levels of plasma interleukin-6 (IL-6), tumor necrosis factor receptor-1 (TNFR-1), and growth differentiation factor-15 (GDF-15) were associated with a higher risk of belonging to the "low in all domains" group (IL-6: relative risk ratio (RRR) [95% CI] = 1.42 [1.07 - 1.88]; TNFR-1: RRR = 1.46 [1.09 - 1.96]; GDF-15: RRR = 1.99 [1.45 - 2.73]). Higher IL-6 and GDF-15 also increased the risk of being in the "low locomotion" group. GDF-15 outperformed other biomarkers by showing the strongest associations with IC trajectory groups. Our findings found that plasma biomarkers reflecting inflammation and mitochondrial impairment distinguished older people with multi-impaired IC trajectories from those with high-stable IC.