Trauma and posttraumatic stress disorder in Japan: Results from the World Mental Health Japan Survey

The purpose of the study was to report the prevalence of trauma exposure and PTSD, conditional risk of PTSD associated with each trauma exposure in the community population in Japan. An interview survey was conducted of a random sample of adult residents in 11 communities of Japan. Among 4134 respondents (response rate, 55%), data from those who completed the part 2 interview (n = 1682) were analyzed with a weight for this subsample. Lifetime experiences of 27 trauma events and PTSD were assessed using the WHO-Composite International Diagnostic Interview version 3.0. Sixty percent of the part 2 sample reported exposure to at least one lifetime traumatic event. Lifetime and 12-month PTSD prevalences were 1.3% and 0.7%, respectively. Percentage of all months lived with PTSD in the population was predominantly accounted for by physical/sexual assaults and having a child with serious illness, and unexpected death of loved one. Ten percent of respondents reported “private events”, for which respondents did not have to describe the content, which accounted for 19% of months with PTSD. The lower prevalence of PTSD in Japan seems attributable to lower conditional risks of PTSD following these events, as well as different distributions of the events. The greater impact of events that occurred to loved ones rather than to oneself and “private events” on PTSD in Japan warrants further research of cross-cultural assessment of trauma exposure and cultural heterogeneity in the trauma-PTSD relationship.