A just-published study of homicides committed by individuals with schizophrenia and bipolar disorder within six months of hospital discharge examined the antecedents of this violent behavior. The study focused on 47 individuals who killed somebody within six months of having been discharged from a psychiatric hospital in Sweden between 1988 and 2001 (Fazel S, Buxrud P, Ruchkin V et al., Homicide in discharged patients with schizophrenia and other psychoses: a national case-control study, Schizophrenia Research 2010 Aug 28 [Epub ahead of print]).
The single largest predictor was, not surprisingly, having been previously hospitalized for a violent episode. As many studies have shown, past violence is the single strongest predictor of future violence. The second strongest predictor was having severe psychotic symptoms. Third was a failure to take medication regularly after having been discharged. And fourth was abusing street drugs and/or alcohol. This picture is consistent with multiple other studies showing that the truly dangerous individuals with schizophrenia and bipolar disorder are those with severe symptoms who do not take medication, abuse drugs and/or alcohol, and have a past history of violence. This group constitutes about 1 percent of all individuals with these diseases (Torrey EF, The Insanity Offense, New York: W.W. Norton, 2008, pp. 179–183). The vast majority of individuals with these diseases are not violent, and for individuals who are taking their medication, studies suggest they are no more dangerous than the general population.
The lead author of the present study is Dr. Seena Fazel, associated with the Department of Psychiatry at the University of Oxford and probably the leading European expert on violence and mental illness. The paper claims that “between 10–20% of homicide perpetrators have psychosis,” consistent with previous European studies. The most recent, and largest, American study of this question reported that just over 10 percent of homicides are committed by individuals with schizophrenia, bipolar disorder, or other psychosis (Matejkowski JC, Cullen SW, Solomon PL, Characteristics of persons with severe mental illness who have been incarcerated for murder, Journal of the American Academy of Psychiatry and the Law 2008;36:74–86).
Since there are currently about 15,000 homicides a year in the U.S., that means that approximately 1,500 of them are committed by individuals with severe psychiatric disorders. The majority of these could be prevented if such individuals were taking the medication they need to control their symptoms. That is why assisted outpatient treatment (AOT) and the work being done by the Treatment Advocacy Center is so important.