Disaster-related home loss, mental health, and risk of cognitive disability: causal mediation analysis using longitudinal data of disaster survivors

Emerging evidence links disaster-related home loss to increased cognitive impairment, yet the mechanisms underlying this association remain unclear. This study examines whether psychopathology and diminished social connection mediate the relationship between home loss and cognitive disability among older disaster survivors. We conducted a prospective cohort study of survivors of the 2011 Great East Japan Earthquake and Tsunami. Causal mediation analysis was used to estimate the role of post-disaster depressive symptoms, post-traumatic stress symptoms, social support, social participation, and social cohesion in mediating the association. Analyses adjusted for pre-disaster confounders. Among 3,138 survivors, 140 experienced disaster-related home loss, and 498 experienced mild to severe cognitive disability. Home loss was associated with increased cognitive impairment, increased psychopathology, as well as decreased social connections. 48% of the total effect of home loss on cognitive impairment was mediated by depressive symptoms, but not post-traumatic stress symptoms. Although the effect was marginal, 19% was also explained by a decline in social cohesion. Disaster-related home loss was associated with subsequent cognitive impairment through post-disaster depressive symptoms and decline in social cohesion. Group relocation and early intervention for those with depressive symptoms might ameliorate the adverse effects of home loss in cognitive disability.