Use of antipsychotic medication has been linked to a significantly reduced risk of psychiatric patients committing violent crime, according to new research published in The Lancet. The study also records an association between mood-stabilizing drugs for people with bipolar disorder and a reduced rate of violent crime.
People with schizophrenia or bipolar disorder are most likely to use antipsychotic treatments such as clozapine or risperidone, or mood-stabilizing drugs such as lithium and carbamazepine. These increasingly popular drugs are known to put psychiatric patients at less risk of relapse and rehospitalization.
However, there has been little research examining how these drugs influence potential adverse outcomes in the community, such as violent behavior.
Violent behavior, the new study notes, is one of the most important adverse outcomes for patients with psychiatric disorders. Previous research has shown that the relative risk of violence against others is four times higher in schizophrenia patients than in the general population.
The risk of interpersonal violence in people with bipolar disorder, meanwhile, is "substantially increased" when the patient is misusing substances.
Studying the influence drugs have on violence risk is difficult, because aggressive patients are less likely to be recruited or give consent to be in a study, and they are less likely to remain enrolled in a study than patients without violent traits. As such, the evidence for antipsychotic drugs to prevent violence in patients is described as "weak or inconclusive."
When participants were using their medication, there was a 45% fall in violent crime among people taking antipsychotics and a 24% decrease in violence among patients using mood stabilizers.
For the new study, researchers in the UK and Sweden analyzed the psychiatric diagnoses and any subsequent criminal convictions of more than 80,000 patients recorded in Swedish health registries. This group were all prescribed either antipsychotic and/or mood-stabilizing medication at some point between 2006 and 2009.
Over the 3-year study period, 6.5% (2,657) of the men and 1.4% (604) of the women in the study were convicted of a violent crime.
Importantly, the researchers compared the periods when individual participants were not using medication with when they were.
Analyzing the results, the study found that when participants were using their medication, there was a 45% fall in violent crime among people taking antipsychotics and a 24% decrease in violence among patients using mood stabilizers.
Antipsychotics and mood stabilizers are often prescribed together, but the study did not find any further decrease in violence when the drugs were combined. Also, the researchers found that mood stabilizers were only associated with reductions in violent crime among male bipolar disorder patients.
Study can prove link between antipsychotics and reduced violence but not cause
The study was not able to make any conclusions about causality from their findings, because the researchers did not investigate how the associations between medication and violent crime are mediated.
For instance, patients with psychiatric disorders who are using medication may receive more support from family or carers, and this could make them less likely to commit violent crime, rather than the effects of the medication itself.
However, the authors point out that this would also mean that people who take mood stabilizers are equally less likely to commit violent crime as people who take antipsychotics, since they would both receive a similar level of support. Instead, the study found that people who took antipsychotics were significantly less likely to engage in violent crime than those who only took mood stabilizers.
Lead researcher Dr. Seena Fazel, of Oxford University in the UK, concludes:
"Until now, we have not known whether antipsychotics and mood stabilizers reduce risks of violence. By comparing the same people when they are on medication compared to when they are not, our study provides evidence of potentially substantial reductions in risk of violence, and suggests that violence is to a large extent preventable in patients with psychiatric disorders."
In 2012, Medical News Today reported on a study that found experienced psychiatrists are better at predicting violence among patients than new doctors.