Depressive symptoms and risk of incident activities of daily living disability among older adults with symptomatic arthritis.

BACKGROUND: Depressive symptoms are highly prevalent among older adults with symptomatic arthritis and may contribute to accelerated functional decline. However, large-scale longitudinal evidence regarding the association between depression and the onset of activities of daily living (ADL) disability remains limited, particularly when competing mortality risks and potential mediating pathways are taken into account. This study aimed to examine the relationship between depressive symptoms and incident ADL disability among older adults with symptomatic arthritis using two nationally representative cohorts.

METHODS: This longitudinal cohort study analyzed data from the US Health and Retirement Study (HRS) and the English Longitudinal Study of Ageing (ELSA). Multivariable Cox proportional hazards models, Fine-Gray competing risk regression models, and discrete-time logistic regression models with follow-up waves as the time scale were used to evaluate the association between depressive symptoms and ADL disability risk. Restricted cubic spline (RCS) analyses were conducted to assess potential non-linear associations. Mediation analyses were performed to quantify the mediating role of physical activity.

RESULTS: During follow-up, 484 participants in ELSA and 1,525 participants in HRS developed incident ADL disability. In both cohorts, higher Center for Epidemiologic Studies Depression Scale (CES-D) scores were significantly associated with an increased risk of ADL disability. In fully adjusted Cox models, each 1-point increase in CES-D score was associated with a 7% higher risk of ADL disability in ELSA (adjusted HR = 1.07, 95% CI: 1.02-1.11) and a 10% higher risk in HRS (adjusted HR = 1.10, 95% CI: 1.07-1.12). Compared with participants without depression, those with depression had a substantially elevated risk of ADL disability (ELSA: adjusted HR = 1.26, 95% CI: 1.04-1.54; HRS: adjusted HR = 1.49, 95% CI: 1.33-1.67). These associations remained robust in competing risk models and discrete-time logistic regression analyses. RCS analyses revealed a dose-response relationship between depressive symptoms and ADL disability risk, with evidence of non-linearity in the HRS cohort. Subgroup analyses demonstrated consistent associations across demographic and clinical subgroups. Mediation analyses indicated that physical activity partially mediated the association between depressive symptoms and ADL disability, accounting for approximately 9.1% of the total effect in ELSA and 5.0% of that in HRS.

CONCLUSION: In both the United States and the United Kingdom, depressive symptoms were independently associated with an increased risk of ADL disability among older adults with symptomatic arthritis. This relationship was robust across multiple analytical frameworks and exhibited a clear dose-response pattern. Physical activity partially mediated this association, highlighting the potential value of integrated mental health and lifestyle interventions to mitigate functional decline in this vulnerable population.