"This is one of the first studies to focus on the severity of inattention problems in childhood attention deficit hyperactivity disorder as distinct from impulsivity and hyperactivity," said Ting-Kai Li, M.D., of the National Institutes of Health. "It demonstrates the usefulness of distinguishing attention deficit hyperactivity disorder’s effects from the effects of childhood behavior disorders such as aggression and defiance. Such prospective longitudinal analysis can best guide us in developing research-based prevention programs specifically targeted to help young people."

Brooke Molina, Ph.D., and William Pelham, Jr., Ph.D., conducted the research with 142 teens between 13 and 18 years of age who had received treatment for childhood attention deficit hyperactivity disorder an average of 5 years earlier at a single university clinic. The researchers interviewed the teens along with their parents and teachers.

The group was 100 peers of similar age who did not have the disorder in childhood.
Investigators asked both groups about their alcohol and substance use, including whether they had ever tried a substance during their lifetime, how old they were when they first tried tobacco, alcohol, or other drugs, and the type, frequency, and quantity of substances used during the past 6 months.

The researchers found that a significantly higher proportion of teens diagnosed with the disorder in childhood reported episodes of alcohol intoxication than their healthy peers. Nearly twice as many youths in the disorder group reported having been intoxicated more than once in the past 6 months.

Both groups gave similar responses when asked if they had ever tried alcohol, cigarettes, or marijuana at least once; however, the adolescents with the disorder were 3 times more likely to have tried an illegal drug other than marijuana. The teens with childhood disorder also reported having used tobacco and having tried an illegal drug other than marijuana at younger ages than their healthy peers. Additionally, about 11 percent of the teens diagnosed with the disorder reported having used 2 or more different illegal drugs more often, compared with 3 percent of the control group.

The researchers analyzed distinctions within the group with childhood attention deficit hyperactivity disorder, focusing on responses from youngsters with more severe symptoms of inattention in childhood. They also examined the differences among individuals with symptoms of comorbid behavior disorders - specifically, oppositional defiant disorder and conduct disorder.

The researchers found that the teenagers who reported more frequent episodes of intoxication, higher alcohol problem scores, and a greater likelihood of substance abuse were those diagnosed with more severe inattention problems in childhood. The youngsters with severe inattention were about 5 times more likely than others to use an illegal drug other than alcohol and marijuana at an early age. The researchers emphasized that inattention appeared to be a uniquely important variable even when the analyses considered the presence of either comorbid behavior disorder, factors that more typically have been considered predictive of substance use.

Although impulsivity-hyperactivity was not associated with teenage substance abuse, the authors wrote that better measurement of this behavior in future studies will be important. Molina said, "The presence of attention deficit hyperactivity disorder during childhood appears to be as strong a risk factor for substance use and abuse as having a positive family history of substance use disorder. It is not specific to only one substance but cuts across alcohol, marijuana, and other drugs. Our findings indicate that the presence of [the disorder] during childhood, the severity of symptoms, and the persistence of the disorder may be risk factors for early substance use and the emergence of substance abuse disorders during the teen years."