Depressive symptoms in the aftermath of major disaster: Empirical test of the social support deterioration model using natural experiment

Introduction: We examined the extent to which the post-disaster deterioration of social support and social capital mediates the associations between disaster-related experiences and depressive symptoms among survivors to test the social support deterioration model. Methods: We used unique natural experiment data (n = 3567) stemming from the 2011 Great East Japan Earthquake. The follow-up survey was conducted 2.5 years after the disaster. We examined associations between changes in depressive symptoms, disaster-related experiences (loss of loved ones, changes in household income, loss of job, drop in subjective economic status, and home loss), and post-disaster deterioration of four different types of social support (i.e., kin emotional, kin instrumental, non-kin emotional, and non-kin instrumental support), as well as two dimensions of individual-level social capital (i.e., informal socializing and social cohesion). We then performed causal mediation analysis. Results: We found that there was deterioration of social support and social capital among individuals with disaster-related experiences. We also found associations between deterioration of social support/capital and worsening of depressive symptoms for specific categories of disaster experiences (i.e., drop in subjective economic status, loss of job, and home loss). However, causal mediation analysis showed little evidence of mediation by post-disaster deterioration of social support/capital. There was some evidence to suggest exposure-mediator interaction such that the association between social support/capital deterioration and depressive symptoms was weaker among those with disaster experiences. Discussion: The social support deterioration model was not empirically supported among older-adult disaster survivors of the 2011 Great East Japan Earthquake, after accounting for exposure-mediator interactions.