The longitudinal posttraumatic stress responses and resilient factors after the Fukushima Daiichi Nuclear Power Plant are yet unknown. Here we attempted to quantify the patterns of the course of posttraumatic stress disorder (PTSD) symptoms and we explored the factors associated with psychological recovery. The subjects were 12 371 residents in the municipalities categorized as the forced evacuated area. We categorized the subjects' PTSD symptoms into 4 groups: Chronic, Resistant, Recovered, and Non-recovered. We applied a logistic regression to clarify the factors related to psychological recovery. We observed that laughter showed significant odds ratio in the Recovered group and the Resistant group. Meanwhile, elderly residents and those with poor living circumstances showed significant odds ratios for the Recovered group and the Resistant group. Laughter in daily life was associated with the psychological health in the evacuation area.
Keywords: disaster psychiatry; laughter; nuclear disaster; posttraumatic stress; psychological health.