Association between multimorbidity and cognitive frailty among the elderly in China: the mediating effect of depressive symptoms

OBJECTIVE: To investigate the relationship among multimorbidity, depressive symptoms, and cognitive frailty (CF) in the elderly, and to explore the mediating effect of depressive symptoms between multimorbidity and CF in the elderly. METHODS: The data for this study were derived from the 2018 China Health and Retirement Longitudinal Study (CHARLS). A sample of the elderly (aged ≥60 years) was selected. The associations of CF with multimorbidity and depressive symptoms were analyzed by logistic regression while adjusting for potential confounding factors. The mediating effect of depressive symptoms between multimorbidity and CF was verified using a Z-test. RESULTS: Among the 9217 participants, there were 6045 older adults with multimorbidity (65.6 %), 3566 with depressive symptoms (38.7 %), and 1591 with CF (17.3 %). Regression analysis showed that both multimorbidity (OR = 2.624, P < 0.001) and depressive symptoms (OR = 2.737, P < 0.001) increased the risk of CF in the elderly. The results of mediation analysis showed that multimorbidity was strongly associated with CF (C = 0.119, P < 0.001). After incorporating depressive symptoms as a mediator into the model of multimorbidity and CF, the relationship between multimorbidity and CF remained significant (C = 0.098, P < 0.001). Z-test results confirmed that the mediating role of depressive symptoms between multimorbidity and CF in the elderly was significant (Z = 2.96, P < 0.001). CONCLUSION: The status of CF in the elderly shouldn't be ignored. Multimorbidity and depressive symptoms are significantly related to CF, which increases the risk of CF in the elderly, and the mediating effect of depressive symptoms is significant in the relationship between multimorbidity and CF in the elderly.