Antipsychotics, Mood Stabilizers May Reduce Violent Crime

Megan Brooks

May 08, 2014

Patients with severe psychiatric illnesses are almost 50% less likely to commit a violent crime when treated with an antipsychotic, a large Swedish study suggests.

"Antipsychotics have potentially large effects on real-world outcomes, such as violent crime, and this needs to be a factor in clinical decision making regarding initiating and maintaining patients on these medications," lead author Seena Fazel, MD, of the Department of Psychiatry, University of Oxford, United Kingdom, told Medscape Medical News.

Mood stabilizers such as lithium or carbamazepine can also help reduce the rate of violent crime, the study suggests, although the reduction is less pronounced than with antipsychotics.

Adding a mood stabilizer to an antipsychotic, "although common in patients with severe mental illness, does not appear to have additional benefits on reducing violent crime than prescribing antipsychotics alone," Dr. Fazel said. "Clozapine appeared to have the strongest reductions in certain crime outcomes than other oral antipsychotics or depot antipsychotics," she noted.

The study was published online May 7 in the Lancet.

Impact on Real-World Events

There is a wealth of evidence that antipsychotics and mood stabilizers provide symptom relief and help prevent relapse in patients with schizophrenia, bipolar disorder, and other serious mental illnesses. But until now, there has been very little evidence on the potential value of these drugs on real-world adverse outcomes, such as reducing violent behavior, the researchers note.

Dr. Fazel's team used linked Swedish national registries to study 82,647 adults who were prescribed antipsychotics or mood stabilizers between 2006 and 2009, their psychiatric diagnoses, and any subsequent criminal convictions (the primary outcome). The cohort included 40,937 men and 41,710 women.

Between 2006 and 2009, 2657 men (6.5%) were convicted of 4166 violent crimes, and 604 women (1.4%) women were convicted of 782 violent crimes.

Compared with periods when participants were not on medication, violent crime fell by 45% (hazard ratio [HR], 0.55; 95% confidence interval [CI], 0.47 - 0.64) in patients receiving antipsychotics, and by 24% (HR, 0.76; 95% CI, 0.62 - 0.93) in patients prescribed mood stabilizers.

"Notable reductions" in violent crime were also seen for depot medication (HR adjusted for concomitant oral medication, 0.60; 95% CI, 0.39 – 0.92), and higher doses of antipsychotics were also associated with reductions in violent crimes (P = .019), the researchers write.

They found no evidence that combining an antipsychotic with a mood stabilizer has any further effect on reducing violent crime.

The addition of a mood stabilizer "does not seem warranted to reduce violence risk" in the patient with schizophrenia, the researchers note. This finding is important because coadministration of antipsychotics and mood stabilizers is common in psychiatry, "despite an uncertain evidence base," they add.

In the study, prescription of a mood stabilizer was associated with reductions in violent crime only in male patients with bipolar disorder.

Although a direct causal interpretation is not possible, the associations uncovered could have important implications for clinical practice, the study team says. The findings point to "potentially substantial reductions in risk of violence," and suggest that "violence is to a large extent preventable in patients with psychiatric disorders," Dr. Fazel said in a statement.

Further Investigation Needed

In a linked commentary, Sheilagh Hodgins, PhD, of Université de Montréal in Canada, notes that about 60% of patients prescribed antipsychotics or mood stabilizers did not have diagnoses of schizophrenia, bipolar disorder, or other psychoses.

"Despite this finding, the reductions in violent crime during periods when medications were dispensed were detected in analyses that included all people prescribed these drugs. These results might represent the increased risk of violent behavior in people with psychotic-like experiences who do not have psychotic disorders. This issue warrants further investigation," Dr. Hodgins writes.

"The study was undertaken carefully, and sensitivity analyses suggest that the results are robust," writes Dr. Hodgins. This "well executed study" provides a basis for future clinical studies to establish how antipsychotics and mood stabilizers can be used to reduce aggressive behavior, she writes.

The study was funded by the Wellcome Trust, the Swedish Prison and Probation Service, the Swedish Research Council, and the Swedish Research Council for Health, Working Life and Welfare. The authors and Dr. Hodgins report no relevant financial relationships.

Lancet. Published online May 7, 2014. Abstract, Comment

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