Cognitive decline and depression risk in middle-aged and older adults: Longitudinal intermediary roles of executive functions and episodic memory

Cognitive decline and depression often co-occur among older adults, however, research exploring the associations between specific cognitive domains and depression remains limited. In this study, we conducted a prospective cohort analysis using three waves of data from the China Health and Retirement Longitudinal Study (CHARLS), including 12,369 middle-aged and older adults aged 45 years and above. Cross-lagged panel models (CLPM) were employed to examine the bidirectional relationship between episodic memory and executive function, as well as their longitudinal, reciprocal mediating effects on depression. The CLPM revealed that executive function (EF) at T1 exerted a significant longitudinal mediating effect on changes in depression at T3 via changes in episodic memory (EM) at T2 (β = -0.004, bootstrap 95 % CI: -0.007 to -0.002). Similarly, EM at T1 had a significant longitudinal mediating effect on changes in depression at T3 through changes in EF at T2 (β = -0.003, 95 % CI: -0.004 to -0.002). There was a significant bidirectional association between EF and EM. Notably, declines in executive function predicted subsequent declines in episodic memory, and this effect was substantially greater than the reverse (β_t1-t2 = 0.187, p < 0.001; β_t2-t3 = 0.152, p < 0.001). This study elucidates the dynamic relationships between these two cognitive domains and depressive symptoms, providing a theoretical basis for developing more targeted prevention and intervention strategies.