Importance: Psychotic persons who are violent often explain their violence as being due to delusions. However, research has failed to confirm associations between delusions and violent behavior.
Objectives: To investigate which delusional beliefs and characteristics are associated with violent behavior during a first episode of psychosis and whether these associations are mediated by affect due to delusions.
Design: Population-based epidemiological survey of first-episode psychosis during a 2-year study period.
Setting: Three inner-city boroughs in East London, England.
Participants: A total of 458 patients with first-episode psychosis who were 18 to 64 years of age.
Interventions: Patients were clinically assessed (using the Schedules for Clinical Assessment in Neuropsychiatry and the Maudsley Assessment of Delusions Schedule) and interviewed about their displaying violent behavior while experiencing psychotic symptoms during the 12-month period prior to interview.
Main outcome measures: Violence was classified at 2 levels of severity: minor and serious violence.
Results: The prevalence of violence was 38% during the 12-month period, and 12% of the sample engaged in serious violence. Distinct sets of demographic and comorbid risk factors were associated with minor and serious violence. These were adjusted for in subsequent analyses. Anger was the only affect due to delusions that was positively associated with violence. The population-attributable risk percentage was 30.8% for minor violence and 55.9% for serious violence. A small number of uncommon delusional beliefs demonstrated direct pathways leading to minor violence. Three highly prevalent delusions demonstrated pathways to serious violence mediated by anger due to delusional beliefs: persecution (z = 3.09, P = .002), being spied on (z = 3.03, P = .002), and conspiracy (z = 2.98, P = .002).
Conclusions and relevance: Anger due to delusions is a key factor that explains the relationship between violence and acute psychosis. A subset of delusional beliefs may be causally linked to violence, and certain uncommon beliefs demonstrated a direct association with minor violence. Highly prevalent delusional beliefs implying threat were associated with serious violence, but they were mediated by anger.