Paranoid Ideation and Violence: Meta-analysis of Individual Subject Data of 7 Population Surveys

There is controversy whether associations between psychosis and violence are due to coexisting substance misuse and factors increasing risk in nonpsychotic persons. Recent studies in clinical samples have implicated independent effects of paranoid delusions. Research findings suggest that individual psychotic-like-experiences on the psychosis continuum in the general population are associated with violence; it remains unclear whether this association is due to psychiatric comorbidity. We pooled data from 7 UK general population surveys (n = 23 444) and conducted a meta-analysis of individual subject data. Further meta-analyses were performed to identify heterogeneity. Main exposure variables: 5 psychotic-like-experiences and a categorical measure of psychosis. Comorbidity was established through standardized self-report instruments. Information was collected on violence, severity, victims. Paranoid ideation was associated with violence (AOR 2.26, 95% CI 1.75–2.91), severity and frequency, even when controlling for effects of other psychotic-like-experiences. Associations were not explained by comorbid conditions, including substance dependence. Psychotic disorder was associated with violence and injury to the perpetrator but associations were explained by paranoid ideation. Individual associations between hypomania, thought insertion, hallucinations, and violence were nonsignificant after adjustments, and significantly associated only when comorbid with antisocial personality disorder. Strange experiences were only associated with intimate partner violence. Paranoid ideation on a psychosis-continuum in the general population was associated with violence. All other associations were explained by comorbidity. Further investigation should determine whether paranoid ideation among persons in the community require preventive interventions, similar to those presenting to mental health services. Nevertheless, risks are considerably increased for psychotic-like-experiences with co-occurring antisocial personality disorder.