Trajectories of intrinsic capacity during ageing: the longitudinal aging study Amsterdam

Introduction: Intrinsic capacity (IC), as defined by the World Health Organization (WHO), represents an individual's physical and mental capacities across five domains: locomotion, cognition, vitality, psychology, and sensory. As a key determinant of functional ability (FA), IC supports meaningful activities, and its decline predicts FA deterioration. Monitoring IC over time may help detect early decline and guide interventions. However, it is not clear how (domains of) IC change during normal ageing. Therefore, this study aimed to identify IC trajectories in both women and men and their associations with functional limitation (proxy of FA) and Quality of Life during ageing. Methods: Data were used from the Longitudinal Aging Study Amsterdam (LASA), a nationally representative Dutch cohort followed over 10 years (1726 females, 1520 males). Latent Class (Growth) Analysis was used to identify trajectories. Results: Three composite IC trajectories were identified in both sexes: most favourable (females: 37.0 %, males: 35.5 %), intermediate (females: 51.1 %, males: 54.4 %), and least favourable (females: 11.9 %, males: 10.1 %). Domain-specific trajectories varied, with three trajectories for vitality, sensory, and psychology in females, while locomotion had two. Males had only two sensory trajectories, while other domains followed similar patterns as in females. The least favourable IC trajectories were associated with worse functional limitations and lower QoL (SF-12 physical and mental scores) in both sexes. Conclusions: Distinct trajectories of composite and domain-specific IC highlight heterogeneity in ageing patterns, with differences between sexes and across IC domains. While composite IC reflects overall capacity, domain-specific trajectories may identify distinct risks and intervention targets.