A mental health advocate and I discussed the recent killing of a pregnant police officer by a paranoid schizophrenic who had recently been released from a state mental institution — even though he had expressed homicidal intentions while in the state’s care. In my opinion, the officer’s tragic death reveals flaws in the mental health care system. The mental health advocate said: “Mental illness and dangerous behavior don’t necessarily belong together.” True. But our conversation prompted me to do some research on the link between mental illness and violent behavior. Here’s some of what I found:

“…there is a moderate but significant association between schizophrenia (or more generally psychotic disorders) and violence… the elevated risk to behave violently appears to be limited to particular symptom constellations. The evidence available so far suggests that the proportion of violent crimes committed by people suffering from a severe mental disorder is small. There is no unambiguous evidence of an increase of violent acts committed by severely mentally ill people in general and people suffering from schizophrenia in particular during recent years. Strangers appear to be at an even lower risk of being violently attacked by someone suffering from severe mental disorder than by someone who is mentally healthy.” (Matthias, 2000)

“An elevated risk of violent behaviour is only evident for specific psychiatric diagnoses and symptom constellations. For schizophrenia and other psychotic disorders, a significant increase in the likelihood to commit violent acts is reported. Substance use disorders and antisocial personality disorder, however, represent a markedly higher risk for violent behaviour.” (Eronen, Angermeyer, Schulze, 1998)

“Objective: The perceived association between violent behavior and serious mental illness was explored to determine the validity of claims by mental health advocates that individuals with serious mental illness are no more dangerous than members of the general population… Results and conclusions: Although the vast majority of individuals with serious mental illness are not more dangerous than members of the general population, recent findings suggest the evidence of a subgroup that is more dangerous… The existence of a subgroup of seriously mentally ill patients who exhibit violent behavior undermines efforts by mental health advocates to reduce the stigma of mental illness by denying an association with violence…” (Torrey, 1997)

To sum up: Most mentally ill people are no more dangerous than non-mentally ill people. But there is a subgroup of seriously mentally ill people who are more dangerous than the general population. They are the ones who make headlines — and stereotypes.

Update: A study by the National Center on Addiction and Substance Abuse at Columbia University (CASA) “reveals that drug and alcohol abuse and addiction are implicated in the incarceration of 80% — 1.4 million — of the 1.7 million men and women behind bars today.” And “Alcohol is more closely associated with crimes of violence than any other drug. It is a bigger culprit in connection with murder, rape, assault and child and spouse abuse than any illegal drug.” More here.