American teens with substance use disorder and conduct disorder are five times more likely to die an early death compared with the general population, a new study concludes.

Conduct disorder is a precursor to antisocial personality disorder in adults. It refers to behavioral and emotional problems in youth that often leads to repetitive aggressive behavior or age-inappropriate violations, the Atlanta Journal-Constitution reports.

The study included 1,463 teens with conduct disorder and substance use disorder, and 1,399 of their siblings. The study also included more than 900 teens without these disorders who were similar in age and demographic background. The researchers found more than 4 percent of the teens with substance use and conduct disorder—and their siblings– had died over the course of 16 years of followup. In contrast, less than 1 percent of teens without substance use and conduct disorder died young.

Boys were nearly three times as likely to die young. Substance use accounted for 32 percent of the early deaths, followed by traffic-related deaths, suicides and assault-related deaths.