Does Helping Others Always Benefit Health? Longitudinal Evidence on the Relationship between Helping Behavior and Depression: The Mediating Role of Life Satisfaction and the Moderating Effect of IADL.

Background: This study aims to explore whether helping behavior is always beneficial for alleviating depression or if there is a "moderation is the key" effect. Materials and Methods: This study focused on a sample of 7,436 participants from the China Health and Retirement Longitudinal Study (CHARLS). The 10-item Center for Epidemiologic Studies Depression Scale (CESD-10) was used to identify the presence of depression. Linear mixed model and Quasi-Bayesian estimation methods were used to explore the mediating role of life satisfaction in the relationship between helping behavior and depression, as well as the moderating effects of the instrumental activity of daily living (IADL). Additionally, we employed the Johnson-Neyman technique to visualize the moderating effect of IADL. Results: Helping behavior shows a negative correlation with depression ( Conclusions: This study highlights the significant positive impact of helping behavior on depression alleviation, which is achieved by increasing life satisfaction. Notably, although helping behavior has positive effects on individuals, not everyone can benefit directly from it. Only those without functional limitations are more likely to experience the benefits of such behavior. Therefore, when policymakers and researchers develop strategies to encourage individuals in helping behavior to combat depression, they should consider two key approaches. First, life satisfaction should be used as an important indicator in the treatment of depression, allowing for timely adjustments to ensure the effectiveness and individualization of treatment plans. Second, the principle of "moderation is the key" should be prioritized, ensuring that helping behavior can maximize its benefits and help individuals emerge from the shadows of depression.