ADL dependence may represent a potential pathway linking chronic lung disease and depression in the middle-aged and older adults: A prospective cross-national cohort study (STROBE).

Previous studies have indicated that middle-aged and older adults with activities of daily living (ADL) dependence or chronic lung disease (CLD) are more susceptible to depression. This study aimed to explore the potential mediating role of ADL dependence. Data from the 2015 to 2020 China Health and Retirement Longitudinal Study (CHARLS), the 2014 to 2019 English Longitudinal Study of Ageing (ELSA), and the 2014 to 2020 Health and Retirement Study (HRS) were utilized for analysis. Spearman correlation analysis was performed to detect correlations among CLD, ADL dependence, and depression. Logistic regression was used to adjust for covariates, and mediation analysis was performed using nonparametric bootstrap and multiple imputation. A total of 18,554 participants, 5,418 from CHARLS, 4560 from ELSA, and 8576 from HRS, were included in this study. The incident depression rates in the CHARLS, ELSA, and HRS cohorts were 27.5%, 11.3%, and 13.4%, respectively. Spearman correlation analysis demonstrated significant associations among CLD, depression, and dependence in both basic ADL and instrumental ADL (P < .05). Across the 3 cohorts, the potential mediating effect of basic ADL dependence on the CLD-depression link accounted for 7.8% in CHARLS, 13.7% in ELSA, and 10.1% in HRS. For instrumental ADL dependence, the potential mediating effect proportions were 6.2% in CHARLS, 9.1% in ELSA, and 12.1% in HRS, respectively. ADL dependence may partially mediate the CLD-depression relationship across diverse populations. However, the effect is weak, and the value of ADL interventions in preventing depression is limited.