18 August 2003
Childhood ADHD May Predict Substance Abuse
by Kate Melville
Scientists tracking the progress of children diagnosed with attention-deficit/hyperactivity disorder (ADHD) as they became teenagers have shed new light on the link between ADHD and the risk of developing alcohol and substance use problems. The researchers found that individuals with severe problems of inattention as children were more likely than their peers to report alcohol-related problems, a greater frequency of getting drunk, and heavier and earlier use of tobacco and other drugs. The findings indicate that childhood ADHD may be as important for the risk of later substance use problems as having a history of family members with alcoholism and other substance use disorders. The study appears in the August issue of the Journal of Abnormal Psychology. ADHD is one of the most commonly diagnosed pediatric mental health disorders. It occurs in three to five percent of school-aged children. While previous research has indicated that ADHD together with a variety of other childhood behavior disorders may predispose children to drug, alcohol, and tobacco use earlier than children without ADHD, this study explores more closely specific aspects of that association.
"This is one of the first studies to focus on the severity of inattention problems in childhood ADHD as distinct from impulsivity and hyperactivity," says Ting-Kai Li, M.D., director of the National Institute on Alcohol Abuse and Alcoholism (NIAAA). "It demonstrates the usefulness of distinguishing ADHD'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," he says. NIAAA supported the study together with the National Institute on Drug Abuse, the National Institute on Mental Health, and the National Institute of Environmental Health Sciences, all components of the National Institutes of Health.
Brooke Molina, Ph.D., at the University of Pittsburgh School of Medicine and University of Pittsburgh Medical Center, and William Pelham, Jr., Ph.D., at the State University of New York at Buffalo conducted the research. The scientists recruited 142 teens between 13 and 18 years old who had received treatment for childhood ADHD an average of 5 years earlier at the Attention Deficit Disorder Clinic at the University of Pittsburgh School of Medicine. The researchers interviewed the teens along with their parents and teachers.
The scientists also recruited a "control" group of 100 similarly-aged teens not diagnosed with childhood ADHD. They 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 drugs, and the type, frequency, and quantity of substances used during the past six months.
The researchers found that significantly more of the teens diagnosed with ADHD as children reported episodes of drunkenness than their counterparts in the non-ADHD group. Nearly twice as many of the ADHD group reported having been drunk more than once in the past six months.
Both groups gave similar responses when asked if they had ever tried alcohol, cigarettes, or marijuana at least once; however, the ADHD group was three times more likely to have tried some other illegal drug besides marijuana. The teens with childhood ADHD also reported having used tobacco and having tried an illegal drug other than marijuana at younger ages than their non-ADHD peers. Additionally, about 11 percent of the teens diagnosed with ADHD reported having used two or more different illegal drugs more often, compared with 3 percent of the control group.
The researchers analyzed distinctions within the ADHD group, focusing on responses from youngsters with more severe symptoms of inattention in childhood, something not routinely done previously. They also examined the differences among individuals with symptoms of comorbid behavior disorders - oppositional defiant disorder (ODD) and conduct disorder (CD).
The researchers found that the teenagers who reported more frequent episodes of drunkenness, 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 point out that inattention appeared to be a uniquely important variable even when the analyses considered the presence of ODD and CD, factors which more typically have been considered predictive of substance use.
Although impulsivity-hyperactivity was not associated with teenage substance abuse, the authors say that better measurement of this behavior in future studies will be important. "The presence of ADHD 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," says Dr. Molina. "Our findings indicate that the presence of ADHD 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."