Long-term trajectories of memory, depression, and mobility independence before death: a multi-cohort study

Cognitive and functional decline are key indicators of mortality risk in older adults. However, temporal onset and progression trajectories of these declines before death, and their cross-national applicability, remain poorly understood. This study aimed to investigate the trajectories of memory performance, depressive symptoms, activities of daily living (ADL), and instrumental activities of daily living (IADL) across four large-scale cohorts: CHARLS (China), ELSA (England), HRS (USA), and SHARE (Europe), to identify patterns associated with imminent mortality. Backward timescale analyses were applied to examine the temporal progression of memory performance, CES-D depressive symptoms, ADL limitations, and IADL impairments leading up to death. Particular attention was given to identifying the onset point and rate of decline associated with mortality. Across the CHARLS, ELSA, HRS, and SHARE cohorts, distinct trajectories in memory performance, depressive symptoms (CES-D scores), ADL, and IADL were observed, highlighting varying patterns associated with mortality as individuals approached death. Memory performance declined significantly in all cohorts, with deceased individuals in CHARLS showing a sharp drop starting 3 years before death (coefficient: -0.0189, p < 0.0001), consistent with trends in ELSA, HRS, and SHARE. CES-D scores progressively increased among deceased individuals, with divergence beginning 6 years before death in CHARLS and 4 years before death in ELSA, peaking at 1 to 2 years before death in most cohorts. ADL scores demonstrated an early decline, with significant differences emerging at 7 years before death in CHARLS and even earlier in HRS (24 years before death), while IADL scores showed more gradual changes, with notable increases in the last 4 to 5 years before death across all cohorts. Memory performance exhibited the strongest association with mortality, followed by ADL scores, emphasizing the critical role of cognitive and functional abilities in end-of-life health trajectories. This study provides cross-national evidence delineating the temporal onset and progression trajectories of cognitive and functional decline before death. Memory performance was the most powerful indicator of imminent mortality, followed by ADL decline. These findings underscore the value of early recognition of declining cognitive and functional abilities among middle-aged and older adults, offering actionable insights for targeted screening, preventive interventions, and end-of-life care planning.