A pair of new studies adds weight to the theory that children who suffer from attention deficit hyperactivity disorder are at higher risk of problem drinking during adolescence and alcoholism later in life.

"Children with ADHD are believed to be at risk for alcoholism because of their impulsivity and distractibility, as well as other problems that often accompany ADHD such as school failure and behavior problems," said Brooke Molina of the University of Pittsburgh, corresponding author for both studies.

In one study, researchers found that 15- to 17-years olds with childhood ADHD reported being drunk an average of 14 times during the previous year, compared to 1.8 times for adolescents without ADHD. Fourteen percent of the ADHD group was classified as alcohol abusers or alcohol dependent, but none of the youths in the non-ADHD group were.

"It appears that one of the reasons for the past inconsistencies in research is that the ADHD-alcohol relationship does not become solid until at least mid-adolescence," said Stephen Hinshaw, professor and chair of the department of psychology at the University of California at Berkeley. "Later on, it may be that only a subset of kids with ADHD -- namely, those with more aggressive or antisocial behavior patterns -- are at risk by young adulthood."

Researchers added that parental alcoholism and family stress add to the alcoholism risk for children with ADHD. "One of the reasons that children with ADHD might be at risk for alcohol problems is that alcoholism and ADHD tend to run together in families," said Molina. "We found that parental alcoholism predicted heavy problem drinking among the teenagers, that the association was partly explained by higher rates of stress in these families, and these connections were stronger when the adolescent had ADHD in childhood. So, the bottom line is that when the child has ADHD and the parent has suffered from alcoholism, either currently or in the past, the child will have an increased risk for alcohol problems himself or herself."

The studies were published in the journal Alcoholism: Clinical and Experimental Research.