The use of mood stabilising drugs (such as lithium or carbamazepine) is also associated with a reduced rate of violent crime, although the reduction is less pronounced, and only in patients with bipolar disorder.
In this study, a team of researchers in the UK and Sweden, led by Dr Seena Fazel of Oxford University, UK, used Swedish national health registries to study the psychiatric diagnoses, and any subsequent criminal convictions, in over 80,000 patients (40,937 men and 41,710 women) who were prescribed antipsychotic or mood stabilising medication, from 2006 to 2009.
In the three years studied, 6.5 per cent (2657) of the men, and 1.4 per cent (604) of women were convicted of a violent crime. Compared with periods when participants were not on medication, violent crime fell by 45 per cent in patients receiving antipsychotics, and by 24 per cent in patients prescribed mood stabilisers.
Although the two types of medication are often combined, the researchers found no evidence that combining the drugs has any further effect on reducing violent crime, and for patients prescribed mood stabilisers, the medication was associated with reductions in violent crime only in male patients with bipolar disorder.
Moreover, although antipsychotic and mood stabilising medications are generally associated with treatment of schizophrenia or bipolar disorder, the researchers found that many people in the study were prescribed these drugs for other disorders, such as depression or alcohol and drug misuse.
The study has been published in The Lancet.