Washington, Oct 17 : Early exposure to drugs and alcohol can put teens at a lifetime health risk, says a new study.
An international team of researchers suggest that kids who began drinking and using marijuana regularly as young as 15 years face a higher risk of early pregnancy, as well as a pattern of school failure, substance dependence, sexually-transmitted disease and criminal convictions that lasts into their 30s.
They tracked 1,000 New Zealand residents from birth through age 32 and found that the people who were using alcohol and marijuana regularly before age 15 were indeed the so-called "bad kids" who came from an abusive, criminal or substance-abusing household and had behaviour problems as children.
However, the other half were the "good kids" from more stable backgrounds, and they also ended up in poorer health in their 30s.
The "good kids," who were without behaviour problems as children and didn't have any of the family risk factors, but began using drugs and alcohol before 15, were 3.6 times more likely to be dependent on substances at age 32.
They were also more likely than the other good kids to wind up with a criminal conviction and a herpes infection.
Good and bad, the adolescents who regularly used drugs and alcohol "all had poorer health as adults," said Duke University psychologist Avshalom Caspi and study's author.
"This is consistent with a growing body of evidence that early adolescence may be a sensitive time for exposure to alcohol and other drugs," Caspi said.
The study also found that a third of the girls from the "good kids" group were pregnant before age 21 if they had been using drugs and alcohol regularly.
That's the same number of pregnancies as the "bad kids" who didn't use drugs.
Moreover, two-thirds of the "bad kids" who used before 15 were pregnant before age 21. By comparison, only 12 percent of "good" girls who were non-users had early pregnancies.
"Even adolescents with no prior history of behavioral problems or family history of substance use problems were at risk for poor health outcomes if they used substances prior to age 15," said first author Candice Odgers of the University of California-Irvine, who did a post-doctoral fellowship with Caspi and Moffitt.
"Universal interventions are required to ensure that all children -- not just those entering early adolescence on an at-risk trajectory -- receive an adequate dose of prevention," she added.
The study is published online by the journal Psychological Science.