For people with severe psychiatric illness, taking an antipsychotic medication appears to drive down the risk of engaging in criminal violence, a large study has found. And for patients diagnosed with bipolar disorder, a mood-stabilizing medication has the same effect.
Those findings, emerging from a large and comprehensive study conducted in Sweden, suggest that when used by those with serious mental illness, these widely prescribed medications not only tame delusions, help restore emotional order and prevent relapses -- they may also reduce the risk to the communities in which these patients live.
The study was published Wednesday in the medical journal Lancet.
The truth about mental illness and violence lies somewhere between two extremes. In the wake of a mass shooting and the inevitable media focus on a perpetrator's mental health, it would be easy to assume that psychiatric illness is the principal cause of community violence. But that is not the case, researchers say.
On such occasions, mental health advocates--fearing an uptick in stigma against those with mental illness--say that those with psychiatric illness are more likely to be victims than perpetrators of violence, leaving an impression that is not entirely accurate. For patients with schizophrenia and other related psychoses, a recent study estimated that the risk of perpetrating violence against other people is fourfold that of the general population. That added risk appears to be concentrated mainly among those with major mental illness who also suffer from alcohol and substance-abuse disorders.
Against that backdrop, little research has been conducted on how psychiatric medication affects the heightened risk of aggression or violence in some with mental illness, and whether some medications might do a better job at driving down that risk. Clinical trials that randomly assign people with diagnosed mental illness to treatment and non-treatment arms wouldn't be ethical. And there's a flaw in studies that merely compare the rate of violent crime perpetrated by medicated psychiatric patients with that of similar patients taking none: Other key differences in these two populations--say, economic status or social support--might account for the two groups' different propensities to commit crime.
So in this study, Oxford University psychiatrist Dr. Seena Fazel and her Swedish collaborators decided to use Sweden's comprehensive records of healthcare, pharmaceutical dispensing and criminal cases to compare the arrest and conviction records of patients with schizophrenia, bipolar disorder and related psychoses when they were on medications with their arrest and conviction records while off medication. They also did a population-wide comparison of medicated patients' violent criminal behavior rates with those of unmedicated patients.
Among the study's 82,647 subjects--all of them prescribed an antipsychotic or mood-stabilizing drug at some point between 2006 and 2009--routinely taking an antipsychotic drug was linked to a 29% reduced probability of being convicted of a drug-related charge, a 22% decline in convictions for any crime, and a 26% reduction in the likelihood of arrest on suspicion of having committed a violent crime. Subjects seeing these reductions took such new-generation antipsychotics as quetiapine (marketed at Seroquel), olanzapine (Zyprexa), risperidone (Risperdal) and aripiprazole (Abilify), or older antipsychotics such as haloperidol (Haldol) or chlorpromazine (Thorazine).
Mood-stabilizing drugs--medications ranging from lithium to neuroleptics such as valproic acid (Depakote), lamotrigine (Lamictal), carbamazepine (Tegretol) and oxcarbazepine (Trileptal)--were on average less powerfully linked to lower crime rates. Compared with periods during which they were unmedicated, when subjects were taking mood-stabilizing drugs, they were, on average, 32% less likely to be convicted of a drug-related crime, 17% less likely to be committed of any crime and 13% less likely to be arrested on suspicion of a violent crime.
When subjects taking one of these mood-stabilizing drugs also had a diagnosis of bipolar disorder, however, the reduction in arrests and convictions was far more robust, researchers said.
The study's authors acknowledge that their study design does not establish medication as the clear cause of a patient's lower propensity to crime. Other factors--including the more regular interaction with a psychiatrist that comes with medication--might help explain the effect.