Mental disorders don't predict future violence

Most psychiatric disorders - including depression—do not predict future violent behavior, according to new Northwestern Medicine longitudinal study of delinquent youth. The only exception is substance abuse and dependence.

"Our findings are relevant to the recent tragic plane crash in the French Alps. Our findings show that no one could have predicted that the pilot - who apparently suffered from depression - - would perpetrate this violent act," said corresponding author Linda Teplin, the Owen L. Coon Professor of Psychiatry and Behavioral Sciences at Northwestern University Feinberg School of Medicine. "It is not merely a suicide, but an act of mass homicide."

The study did find, however, that some delinquent youth with current psychiatric illness may also be violent. For example, males with mania were more than twice as likely to report current violence than those without. But these relationships are not necessarily causal.

Delinquent youth with psychiatric illness have multiple risk factors—such as living in violent and impoverished neighborhoods. These environments may increase their risk for violent behavior as well as worsen their psychiatric illness.

"Providing comprehensive treatment to persons with some psychiatric disorders could reduce violence," said Katherine Elkington, study first author and an assistant professor of clinical psychology in psychiatry at Columbia University Medical School and New York Psychiatric Institute. "We must improve how we address multiple problems—including violent behavior—as part of psychiatric treatment."

The article was recently published in the Journal of the American Academy of Child & Adolescent Psychiatry.

The study used data from the Northwestern Juvenile Project, a longitudinal study of youth who were detained at the Cook County Juvenile Temporary Detention Center in Chicago between 1995 and 1998. Violence and psychiatric disorders were assessed via self-report in 1,659 youth aged 13 to 25 years interviewed up to four times between three and five years after detention.