Triggers for violent criminality in psychotic disorders: A nationwide Swedish within-individual study of 3.1 million persons

Importance Absolute and relative risks of violence are increased in psychotic disorders, but the contribution of triggers for violent acts is uncertain. Objectives To examine whether a range of triggers are associated with violence risk in patients diagnosed with psychotic disorders and in individuals without a psychiatric diagnosis. Design, Setting and Patients Using a sample of all individuals born in Sweden between 1958 and 1988 (n=3,123,724), we identified patients in the National Patient Register who were diagnosed with schizophrenia-spectrum disorders (n=34,903), bipolar disorder (n=29,692) and unaffected controls (n=2,763,012). We then identified, within each sub-sample, persons who had experienced any of the following triggers between 2001 and 2014: violent victimisation, parental bereavement, self-harm, traumatic brain injury, unintentional injuries, and substance intoxication. By using within-individual models, we conducted conditional logistic regression to compare the risk of the individual engaging in violent acts in the week following the exposure to a trigger with earlier time periods of equivalent length. All time-invariant confounders (e.g., genetic and early environmental influences) were controlled for by this research design and we further adjusted for time-varying socio-demographic factors. Main Outcomes and Measures Adjusted odds ratios (aORs) of violent crime occurring in the week following the exposure to a trigger compared with earlier time periods. Results All of the examined triggers were associated with increased risk of violent crime in the week following exposure. For most triggers, the effects did not vary significantly by diagnosis, including unintentional injuries (aORs ranging from 3.5 to 4.8), self-harm (aORs=3.9-4.2), and substance intoxication (aORs=3.0-4.0). Differences by diagnosis included parental bereavement, which was significantly higher in patients with schizophrenia-spectrum disorders (aOR=5.0; 95% CI: 3.0-8.1) compared to individuals without a psychiatric diagnosis (aOR=1.7; 95% CI: 1.3-2.2). Interpretation In addition to identifying risk factors for violence, clarifying their timing may provide opportunities to improve risk assessment and management in individuals with psychotic disorders