MedWire News: A minority of schizophrenia patients are prone to violence, but treatment with antipsychotic medications may help reduce the risk of violent behaviour in some of these patients, US study results show.

"Violent behaviour, although infrequent among people with schizophrenia in the community, remains a costly and sometimes tragic problem," explain Dr Jeffrey Swanson, from Duke University Medical Center in Durham, North Carolina, and colleagues.

However, they add that it is not known whether antipsychotic medication reduces violent behaviour in schizophrenia patients.

To investigate, the researchers studied 1445 patients with schizophrenia who were assigned to take one of five antipsychotic medications.

The team found that the overall prevalence of violent behaviour among the participants declined from 16% and the start of treatment to 9% after 6 months.

However, further analysis revealed that the beneficial effects of antipsychotic medications on violent behaviour only applied to patients in whom such behaviour was linked to psychotic symptoms.

Indeed, among a subgroup of patients with a history of childhood conduct problems whose violent behaviour was not related to psychotic symptoms, antipsychotic medications had little effect on such behaviour.

The team also found no difference between newer and older types of antipsychotic medication regarding their effects on violent behaviour.

Commenting on the findings, co-researcher Dr Marvin Swartz, also from Duke University Medical Center, said: "In the past, we've not understood very well why a small proportion of patients with schizophrenia become seriously violent, while most do not, and why medication seems to prevent violent behaviour in some and not others.

"These findings tell us that people with schizophrenia may behave violently for reasons not directly related to their mental illness. If that's the case, then treatment for psychotic symptoms alone may not eliminate the risk of violence."

He added: ""Antipsychotic drugs may help reduce violence risk, but they don't address all of the causes of violent behaviour and they don't help at all if people can't or won't take the medication prescribed. We also need interventions to help patients stay engaged in treatment."

The research is published in the British Journal of Psychiatry.