Compliance with antipsychotic medications can reduce violent behavior in schizophrenic patients without a history of childhood antisocial conduct, according to a report in The British Journal of Psychiatry for July. In those with this history, other medications and interventions are likely to be required.

The findings also suggest that the newer, more expensive atypical antipsychotics are no better at reducing violence than perphenazine, an antipsychotic agent that has been used for decades.

“There are some (schizophrenic) patients with acute psychotic symptoms — hallucination and delusions — who become violent. In those patients, treating the symptoms should reduce the risk of violence. This study suggests that is the case,” lead author Dr. Jeffrey W. Swanson, from Duke University School of Medicine in Durham, North Carolina, told Reuters Health.

Dr. Swanson said that there are also a large number of patients with a history of childhood antisocial conduct. “For patients with this antisocial history, we think adult violent behavior is largely connected to problems that develop earlier in life, before the onset of psychotic illness.” Thus, he added, it was not surprising that antipsychotic therapy had little impact on violence in this group.

The findings stem from the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) study, which involved 1445 patients with schizophrenia who were randomized to receive perphenazine, olanzapine, quetiapine, risperidone, or ziprasidone. Outcomes were assessed for the intention-to-treat sample as well as for patients who completed 6 months of treatment with the assigned agent.

In the intention-to-treat sample, the rate of violent behavior dropped from 19.1% at baseline to 14.0% over the course of the study. In the retained sample, the violence rate fell from 16.3% to 9.3%.

No significant differences in anti-violence efficacy were noted between the drugs in the intention-to-treat sample. In the retained sample, however, perphenazine was more effective than quetiapine.

Risk factors for violence included a history of childhood antisocial conduct, substance abuse, victimization history, economic deprivation, and social living situation. By contrast, negative psychotic symptoms were linked to reduced violence.

“I think the message is that taking antipsychotic medications is likely to reduce the risk of community violence for some, but not all individuals with schizophrenia,” Dr. Swanson concluded. “Some people with mental illness may become violent for the same reasons that anyone one else might become violent — such as having a violent childhood or abusing alcohol or drugs — and not primarily because they have a mental illness. Clearly, psychiatric medication is never going to fix all the causes of violence in society.”

Br J Psychiatry 2008.

By Anthony J. Brown, MD