Adolescents with serious conduct and substance use problems are five times more likely to die prematurely than their peers, with roughly one in 20 dying by their 30s, according to new CU Boulder research.

The study, published today in the journal Addiction, also suggests that while drug and alcohol use among adolescents draws more attention, antisocial behavior—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, a graduate student with the Institute for Behavioral Genetics.

For the study, Border and his colleagues looked at death rates among 1,463 adolescents who had been arrested or referred to counseling for substance use problems and/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 their siblings and a control group of 904 adolescents of similar age and demographic background.

The researchers decided to do the study after, while following up with subjects from the ongoing Genetics of Antisocial Drug Dependence study launched in 1993, they made a troubling discovery: Several had already died. They used mortality data from the National Death Index to determine how many.

With an average follow-up age of 32.7 years, they found that 62 of the original study subjects—more than 4 percent—had died, compared to less than 1 percent of controls. Siblings of the study subjects also had higher mortality rates, with about 2.4 percent dying.

We pay a lot of attention to substance use and it is definitely important, but we don’t put as much attention on rule breaking. Perhaps we should.” –John Hewitt, Institute for Behavioral Genetics

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

“To see detailed, hard data from a cohort of adolescents we have been interviewing face-to-face over the years really makes tangible the dangers that these youth are facing as they go into adulthood,” said co-author John Hewitt, IBG director. “It’s a strikingly poor outcome and should be a major public health concern.”

When the researchers further analyzed 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.

“We pay a lot of attention to substance use and it is definitely important, but we don’t put as much attention on rule breaking,” said Hewitt. “Perhaps we should.”

Between 6 to 16 percent of boys and 2 to 9 percent of girls meet the criteria to be diagnosed with conduct disorder, previous studies show. Previous CU Boulder research suggests that genetic variants may play a role in making a child more prone to risk-taking or anti-social behaviors.

Because the study focused on youth whose conduct was serious enough they had been arrested or referred to therapy, it’s uncertain to what degree the findings apply to the broader population.

But the takeaway is clear, said Hewitt.

“If you have an adolescent who is exhibiting extreme conduct problems, seek help. It is not just a matter of stopping them from doing bad things. It could be a matter of keeping them alive.”