Association between depressive symptoms and sarcopenia among middle-aged and elderly individuals in China: the mediation effect of activities of daily living (ADL) disability
Authors: Li Qiugui , Cen Wenjiao , Yang Tao , Tao Shengru 
Published: June 2024

Abstract
Background
Depressive symptoms and sarcopenia, often observed among middle-aged and elderly individuals, are significant health concerns in China, particularly given the country’s rapidly aging population. Depressive symptoms, characterized by persistent feelings of sadness and loss of interest, can significantly impact quality of life. Little is known about the underlying pathway connecting these two conditions.

Methods
The data for this study were derived from the China Health and Retirement Longitudinal Study (CHARLS). Depressive symptoms were evaluated using the Centre for Epidemiological Studies Depression (CSED) scale. Logistic regression analyses were employed to investigate the association between depressive symptoms, activities of daily living (ADL) disability, and sarcopenia, while adjusting for potential confounding factors. The selection of predictor variables, including social activity, chronic diseases, demographic factors, and lifestyle habits, was based on their known associations with mental health, physical functioning and sarcopenia. These variables were included to ensure a comprehensive adjustment for potential confounding factors and to provide a more accurate estimation of the relationship between depressive symptoms and sarcopenia. Additionally, mediation analysis was conducted to assess the mediating role of ADL disability in the relationship between depressive symptoms and sarcopenia.

Results
A comprehensive study was conducted on a total of 8,238 participants aged 45 years and older, comprising 3,358 men and 4,880 women. Logistic regression analyses were conducted to identify significant associations between depressive symptoms (OR = 1.30, P = 0.0269,95%CI = 1.03–1.63), ADL disability (OR = 1.94, P < 0.001,95%CI = 1.37–2.75) and sarcopenia. The results revealed significant relationships among these variables. Furthermore, mediation effect analyses demonstrated that ADL disability partially mediated the association between depressive symptoms and sarcopenia (estimated indirect effect: 0.006, 95% CI: 0.003, 0.008, proportion of mediation effect: 20.00%).

Conclusions
The study underscores a significant association between depressive symptoms and sarcopenia among middle-aged and elderly individuals in China, with ADL disability acting as a mediator. These findings offer novel insights for targeted health interventions. Future interventions should effectively combat sarcopenia by integrating psychological support with muscle-strengthening exercise programs. By addressing both depressive symptoms and ADL disability, clinicians and public health professionals can enhance outcomes for this demographic. Collaborative efforts across disciplines are essential for providing comprehensive health management tailored to the needs of middle-aged and elderly individuals. Future research should longitudinally assess the impact of such integrated interventions on sarcopenia prevention and depressive symptom alleviation. Additionally, investigating the role of social and environmental factors in mediating this relationship is crucial for developing more effective health strategies for this vulnerable population.