New York, Aug 11 (IANS): Parents, please take note. A new study has found that adolescents with serious conduct and substance use problems are five times more likely to die prematurely than their peers.

The findings, published in the journal Addiction, suggests that while drug and alcohol use among adolescents draws more attention, antisocial behaviour -- including rule-breaking tendencies -- may be a more powerful predictor of early mortality.

"This research makes it clear that youth identified with conduct problems are at extreme risk for premature mortality, beyond that which can be explained by substance use problems, and in critical need of greater resources," said lead author Richard Border from the University of Colorado Boulder in the US.

For the study, the team looked at death rates among 1,463 adolescents who had been arrested or referred to counselling for substance use problems or "conduct disorder", a mental health disorder characterized by rule-breaking aggression toward others, property destruction and deceitfulness or thievery.

They also followed 1,399 of the participant's siblings and a control group of 904 adolescents of similar age and demographic background.

With an average follow-up age of 32.7 years, the researchers found that 62 of the original study subjects -- more than four per cent -- had died, compared to less than one per cent of the controls.

The team also found that siblings of the study subjects also had higher mortality rates, with about 2.4 per cent dying.

Substance-related deaths were the most common, along with traffic related deaths, suicides and deaths resulting from assaults, the researchers said.

When the researchers further analysed the data, they were surprised to discover that while both conduct disorder and substance use severity were associated with increased mortality risk, conduct disorder was a more powerful independent risk factor.