Onset and remission of common mental disorders among adults living in temporary housing for three years after the triple disaster in Northeast Japan

Background: People living in temporary housing for long periods after a disaster are at risk of (developing) poor mental health. This study investigated the post-disaster incidence and remission of common mental disorders among adults living in temporary housing for the three years following the 2011 Great East Japan Earthquake. Methods: Three years after the disaster, face-to-face interviews were conducted with 1,089 adult residents living in temporary housing in Japan (the shelter group) and a random sample of 852 community residents of East Japan (the general population). The World Health Organization Composite International Diagnostic Interview (CIDI) was used to diagnose DSM-IV mood, anxiety, and alcohol use disorders. Information on demographic variables and disaster experiences was also collected. Results: Response rates were 49% and 46%, for the shelter group and general population, respectively. The incidence of mood/anxiety disorder in the shelter group was elevated only in the first year post-disaster compared to that of the general population, although the rate of remission was significantly lower in the shelter group. The proportion seeking medical treatment was higher in the shelter group. Conclusions: The onset of common mental disorders increased in the first year, but then levelled off in the following years among residents in temporary housing after the disaster. Remission from incident post-disaster mental disorders was slower. Post-disaster mental health service is required to take into account the prolonged remission of mental disorders among survivors with a long-term stay in temporary housing after a disaster.