Social causation or social selection? The longitudinal interrelationship between poverty and depressive symptoms in China

Rationale: To our knowledge, no prior studies have investigated these bidirectional pathways between poverty and depressive symptoms to identify potential mechanisms. Objective: This study aimed to investigate the interrelationship between poverty and depressive symptoms by examining two causal theories: social causation, which claims that the condition of poverty causes mental health disorders, and social selection, which suggests that those with poor mental health are more likely to drift into poverty. Method: We obtained data from 17,250 adults aged 45 years or above from the China Health and Retirement Longitudinal Studies, first conducted in 2011-2012. Participants were tracked for 4 years, with baseline measurements taken as well as two 2-year follow-up visits. Structural equation models were used to examine the pathways in two directions at baseline, 2-year follow-up and 4-year follow-up. Results: We found significant total effects and indirect effects of poverty on depressive symptoms at baseline, which were mediated through deterioration of household living conditions, decrease in social participation, and decline in life satisfaction. In the opposite direction, depressive symptoms directly led individuals to drift into poverty at baseline and at follow-up. Conclusions: This study suggested that social causation and social selection may operate concurrently. Proactive interventions, especially ones focusing on modifiable protective factors that our findings identified as mediators in the link between poverty and depression, are urgently needed to break the vicious cycle of poverty and depression and create a virtuous cycle of increasing returns.