The interplay of multimorbidity and depressive symptoms: mediation role of functional dependence

Mental-physical multimorbidity is an emerging prevalent global health challenge. This study aims to examine reciprocal relationships between depressive symptoms and multimorbidity, with the mediation role of functional dependence in activities of daily living.

Data were derived from the China Health and Retirement Longitudinal Study, which included 11,572 Chinese residents aged 45 years and older, surveyed in 2011, 2013, 2015 and 2018. Depressive symptoms were assessed using the Chinese version of the Center for Epidemiologic Studies Depression Scale (CESD-10) at baseline and each follow-up survey. Multimorbidity was operationalized as the condition count and the patterns identified via exploratory factor analysis. Four-wave cross-lagged panel models (CLPM) with bootstrapping were employed to estimate the path coefficients and the mediation effect of functional dependence.

Multimorbidity (cardiometabolic and respiratory-degenerative) and depressive symptoms exhibited bi-directional associations. Multimorbidity had a stronger impact on later depression (β: 0.042-0.130) than depression on multimorbidity (β: 0.005-0.064). Associations were stronger for respiratory-degenerative (β: 0.027-0.104) than cardiometabolic diseases (β: 0.005-0.065). Functional dependence partially mediated these links, with higher mediation for cardiometabolic (9-21%) than respiratory-degenerative diseases (4-6%). Additionally, some sex- and age-specific differences were identified in these dynamic associations.

The study revealed bi-directional links between multimorbidity and depressive symptoms among Chinese adults. Functional dependence was a significant pathway in the cycle of multimorbidity and depressive symptoms, especially for cardiometabolic diseases. These insights suggest that interventions aimed at preventing functional dependence may be beneficial in mitigating the risk of coexisting mental and physical disorders.