Persistent mental health impacts of disaster. Five-year follow-up after the 2011 great east Japan earthquake and tsunami: Iwanuma Study

Few studies have tracked the long-term mental health outcomes following major disaster. We sought to document the trajectories of depressive symptoms and post-traumatic stress symptoms (PTSS) in the aftermath of the 2011 Great East Japan earthquake and tsunami. A cohort of community-dwelling older adults were followed for 5.5 years after the disaster at 3 waves (2010, 2013 and 2016). Depressive symptoms were measured by the Geriatric Depression Scale Short Form, while PTSS was assessed by the Screening Questionnaire for Disaster Mental Health. We examined the trajectories of mental illness symptoms based on the probabilities of persistence, recovery, and delayed onset. Among people without pre-disaster depressive symptoms, 13.6% had developed depressive symptoms 2.5 years after the disaster. Of these, half of those had recovered and half had persisted at the 5.5 year follow-up. 11.1% of survivors reported post-traumatic stress symptoms in 2013; of these, 58% recovered by 2016, while 4.8% experienced delayed onset. Job loss was associated with persistent PTSS (OR 2.03; 95%CI 1.01–4.12) while a drop in subjective economic status predicted delayed onset of PTSS (OR 2.13; 1.34–3.39). However, disaster-related experiences were unrelated to the trajectory of depressive symptoms at 5.5 years. The probabilities of remission (58%) and delayed onset (5%) of PTSS are consistent with prior disaster research. The experience of job loss and drop in subjective economic status appeared to exert a lingering influence on the persistence or delayed onset of PTSS. Depressive symptoms after the disaster had remitted in roughly half of the survivors after 5.5 years.