Mediation analysis of cognitive function in the relationship between pulmonary function and depression among middle-aged and older adults

Aim: This study aims to explore the association between declining lung function and depression in middle-aged and older adults, with a special focus on the mediating role of cognitive function. Methods: This study utilizes self-reported and physical examination data from 5345 individuals participating in the 2015 cycle of the China Health and Retirement Longitudinal Study (CHARLS) to explore the role of cognitive function changes in mediating the effects of diminished lung function on depression among middle-aged and older adults. Results: Multivariate linear regression analysis revealed a positive correlation between pulmonary and cognitive functions (beta=0.003, 95% CI: 0.002 similar to 0.003,P< 0.01) and a negative correlation between cognitive function and depression (beta= -0.279, 95% CI: -0.330-0.228,P< 0.01). Cognitive function plays a mediating role in linking pulmonary function with depression, exhibiting a mediation effect of -0.0007 and a total effect of -0.0046, wherein the mediation effect contributes to 15.22% of the total effect. For females, the mediating effect of cognitive function was stronger (beta= -0.0013, 95% CI:-0.0018 similar to-0.0008,P< 0.01)than it was for males (beta= -0.0006, 95% CI: -0.0009 similar to-0.0003,P< 0.01). Conclusions: The study underscores the importance of monitoring lung and cognitive functions as interconnected factors contributing to the mental health of middle-aged and older adults. It suggests that interventions aimed at improving pulmonary health and cognitive function may help mitigate depressive symptoms among middle-aged and older adults. Further research is warranted to validate these findings across diverse cultural and demographic settings