Schizophrenia spectrum disorders tied to increased risk for perpetrating violence

People with schizophrenia spectrum disorders appeared to have increased risk for perpetrating violent outcomes compared with community control individuals, according to a systematic review and meta-analysis published in JAMA Psychiatry.

“A previous systematic review identified 20 primary studies from 11 countries that reported a substantial increase in risk of violence perpetration in individuals with schizophrenia compared with people without schizophrenia, and a doubling of risk with substance misuse comorbidity,” Daniel Whiting, BM, BCh, of the department of psychiatry at the University of Oxford in England, and colleagues wrote. “However, the search period for this review ended in February 2009. Since then, several large population investigations have been conducted.”

According to the researchers, the more recent studies involved enhanced techniques for investigating confounding, testing comorbidities and allowing for examination of additional outcomes, yet recent quantitative analyses have yet to incorporate these new data. Whiting and colleagues searched databases for studies in any language that were conducted between January 1970 and March 2021. They searched for the terms “violen*,” “homicid*,” “psychosis,” “psychoses, “psychotic,” “schizophren*,” “schizoaffective” and “delusional,” as well as for terms for mental disorders. They included case-control and cohort studies that compared risk for interpersonal violence perpetration and/or violent criminality among people with schizophrenia spectrum disorders with a general population group without these disorders. Violence to others determined via official records, self-report and/or collateral-report, or medical file review that included any physical assault, robbery, sexual offenses, illegal threats or intimidation, and arson served as the main outcome.

In the meta-analysis, Whiting and colleagues included 24 studies of violence perpetration outcomes in 15 countries across 4 decades, with 51,309 participants with schizophrenia spectrum disorders. Participants had a reported mean age of 21 to 54 years at follow-up. Studies that reported outcomes separately by sex had 19,976 males and 14,275 females.

Men with schizophrenia and other psychoses (pooled OR = 4.5; 95% CI, 3.6-5.6) had an increased risk for violence perpetration with substantial heterogeneity. Women (pooled OR = 10.2; 95% CI, 7.1-14.6) also had increased risk with substantial heterogeneity. Those with schizophrenia spectrum disorders exhibited increased risk for perpetrating sexual offenses (OR = 5.1; 95% CI, 3.8-6.8) and homicide (OR = 17.7; 95% CI, 13.9-22.6). A total of three studies showed increased relative risks for arson; however, data were not pooled for this analysis due to heterogeneity of outcomes. In register-based studies of people with schizophrenia spectrum disorders, women had an absolute risk for violence perpetration of less than one in 20 and men of less than one in four over a 35-year period.

“Prevention of violence perpetration should be a target for clinical services that assess and treat individuals with these disorders,” Whiting and colleagues wrote. “New work should consider preventive approaches, including the improvement of the clinical assessment of risk and targeted resource allocation to treat modifiable factors. Violence perpetration outcomes should be routinely collected in studies of the effectiveness of clinical services and therapeutic interventions.”