The relationship between social isolation, depressive symptoms and cognitive function in older adults: a longitudinal mediation study in China.

Purpose: Both social isolation and cognitive impairment are important public health issues that affect the quality of life of older adults. Our study aims to clarify the direction of their relationship and to illustrate the mediating role played by depressive symptoms.

Methods: Data from 5399 respondents who participated in three longitudinal surveys in the China Health and Retirement Longitudinal Survey (CHARLS) were analyzed. Cross-lagged panel model was used to determine the longitudinal relationship between social isolation, depressive symptoms, and cognitive function.

Results: After controlling for confounders, higher levels of social isolation predicted subsequent more severe cognitive function score (wave1-wave2: β = - 0.039, SE = 0.015, P = 0.009; wave2-wave3: β = - 0.057, SE = 0.017, P = 0.001), and 37.5% of this effect was mediated through depressive symptoms (β = - 0.002, SE = 0.001, P = 0.022). Similarly, lower cognitive function predicted subsequent higher social isolation (wave1-wave2: β = - 0.062, SE = 0.014, P < 0.001; wave2-wave3: β = - 0.039, SE = 0.015, P = 0.009), but depressive symptoms did not play a mediating role in this process (β = - 0.001, SE = 0.001, P = 0.072).

Conclusion: There is a potential bidirectional relationship between social isolation and cognitive function in which depressive symptoms play a partially mediating role.