Comparison of antipsychotic medication effects on reducing violence in people with schizophrenia

Background: Violence is an uncommon but significant problem associated with schizophrenia. Aims: To compare antipsychotic medications in reducing violence among patients with schizophrenia over 6 months, identify prospective predictors of violence and examine the impact of medication adherence on reduced violence. Method: Participants (n=1445) were randomly assigned to double-blinded treatment with one of five antipsychotic medications. Analyses are presented for the intention-to-treat sample and for patients completing 6 months on assigned medication. Results: Violence declined from 16% to 9% in the retained sample and from 19% to 14% in the intention-to-treat sample. No difference by medication group was found, except that perphenazine showed greater violence reduction than quetiapine in the retained sample. Medication adherence reduced violence, but not in patients with a history of childhood antisocial conduct. Prospective predictors of violence included childhood conduct problems, substance use, victimisation, economic deprivation and living situation. Negative psychotic symptoms predicted lower violence. Conclusions: Newer antipsychotics did not reduce violence more than perphenazine. Effective antipsychotics are needed, but may not reduce violence unrelated to acute psychopathology.