Family violence is a serious concern in the era of deinstitutionalization in Japan. Consequently, we aimed to clarify the rate of family violence among patients with schizophrenia, and differences by sex and relationship to the patient. We asked households belonging to a family group association to complete a self-administered mail survey. Of 350 households that responded, data for 302 were analyzed. The rate of violence toward any family member was 60.9% over the lifetime and 27.2% in the past year. Order of lifetime rates for family members from highest to lowest was 51.0% for mothers, 47.0% for fathers, 30.7% for younger sisters, 23.8% for spouses, 19.5% for younger brothers, 18.2% for older sisters, 17.1% for older brothers, and none for children. Younger sisters were more likely to be victims compared to other siblings. Fathers and older brothers were likely to be victims when patients were male.

The present study conducted in Japan aimed to clarify the relationship between violence directed towards parents by patients with schizophrenia and parents’ risk of post-traumatic stress disorder (PTSD). Questionnaire data from 353 parents were analyzed. In total, 84 of the 353 parents (23.8%) reported the Impact of Event Scale-Revised (IES-R) score ≥ 25 (high-IES-R), indicative of a high risk of developing PTSD. The rate of high-IES-R scores was significantly higher among parents who had experienced an act of violence that was likely to result in severe injury by their adult child with schizophrenia (OR = 2.03; 95% CI 1.09–3.80; using “never experienced” as a reference) and in parents of patients who were hospitalized at the time of the survey (OR = 2.47; 95% CI 1.01–6.06; using “regularly visited a psychiatrist” as a reference). Therefore, parents experiencing violence by their adult child with schizophrenia are at a risk of developing PTSD. Parents of patients with schizophrenia, who are at a high risk of PTSD, are not usually provided the required support in Japan. To prevent violence and provide support for family members who may develop PTSD, it is necessary to establish crisis intervention programs, especially given the current emphasis on deinstitutionalization policy in Japan.