New York, April 27 (IANS): Contrary to popular perception, people suffering from depression may not be more prone to commit violent acts in the future, says a new research.

The fact that the German co-pilot suspected to be behind the deadly plane crash in the French Alps last month, killing himself along with the 149 people on board, was apparently suffering from depression has prompted many to speculate that most psychiatric disorders could lead to violent behaviour.

According to the new findings only substance use disorders predict future violence.

"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, professor at Northwestern University Feinberg School of Medicine in the US.

"It is not merely a suicide, but an act of mass homicide," Teplin noted.

The study did find, however, that males with mania were more than twice as likely to report current violence than those without. But these relationships are not necessarily casual, the researchers noted.

Delinquent youth with psychiatric illness have multiple risk factors -- such as living in violent and impoverished neighbourhoods -- the study emphasised.

The study used data from 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.

"We must improve how we address multiple problems -- including violent behaviour -- as part of psychiatric treatment," study first author Katherine Elkington, assistant professor of clinical psychology in psychiatry at Columbia University Medical School, pointed out.

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