The complex relationship between the digital divide, social capital, and mental health among older adults: a multi-method path decomposition.

Background: Against the backdrop of converging population aging and digitalization trends, the impact of the digital divide on older adults' mental health represents a paradox characterized by conflicting empirical findings. Methods: To address this paradox, this study employs a multi-method analytical strategy-comprising propensity score matching, panel fixed-effects models, and generalized structural equation modeling-utilizing nationally representative data from the China Family Panel Studies (CFPS) 2016-2022. This approach systematically decomposes the complex causal pathways connecting the digital divide, social capital, and mental health among older adults. Results: After rigorously controlling for self-selection bias and time-invariant individual heterogeneity, our findings initially demonstrate a robust null total effect of the digital divide on depressive symptoms among older adults [average treatment effect on the treated (ATT) = 0.02, t = 0.10, p > 0.1]. However, subsequent mechanism analysis reveals that this null effect represents a statistical artifact arising from a suppression effect. Specifically, a beneficial direct pathway (direct effect of physical access on depression: β = -0.052, p < 0.1) is offset by a detrimental indirect pathway, wherein higher-order "motivational access" undermines bridging social capital (effect on interpersonal relationships: β = -0.207, p < 0.001), which subsequently serves as a protective factor for mental health (effect on depression: β = -0.032, p < 0.1). Conclusion: This study empirically establishes that the digital divide functions as a double-edged sword for older adults' mental health, with its net effect contingent upon the complex interplay between direct technological benefits and indirect social costs. These findings indicate that future digital inclusion policies must transcend the narrow focus on bridging physical access gaps to prioritize "empowering trust." This objective can be realized through targeted digital literacy interventions that enable older adults to navigate technology safely, thereby advancing the broader policy objective of healthy aging.