Monday, January 6, 2003, 12:01 am (ET)

Hyperactive Children Treated with Stimulants Not at Increased Risk for Drug Abuse Later in Life, Medical College Study Finds

Children diagnosed with hyperactivity/ADHD (attention deficit hyperactivity disorder) are at no greater risk for using illegal drugs when they are teenagers or adults than children who are not treated with such drugs, according to a longitudinal study recently completed at the Medical College of Wisconsin. The results of the study are published in the Jan. 6, 2003, issue of Pediatrics.

The Medical College study was led by a research team of Russell Barkley, Ph.D., currently professor in the College of Health Professions at the Medical University of South Carolina, and Mariellen Fischer, Ph.D., professor of neurology at the Medical College. Their study concurred with ten previous studies that found no evidence that treating hyperactive children with stimulants "sensitizes" them to drugs and increases their risk of later drug abuse. An eleventh study, however, found an increased risk of cocaine use later in life by children treated with stimulants; one of the purposes of the Medical College study was to test that finding.

The 23 year-old study followed children first seen at Milwaukee Children's Hospital, now Children's Hospital of Wisconsin, and then at Froedtert Hospital, major pediatric and adult teaching hospital affiliates of the Medical College.

"Our findings show very little support for the sensitization hypothesis or the possibility that treatment with stimulant medication, either in childhood or adolescence, contributes to a significant risk for lifetime substance use, dependence or abuse," said Dr. Fischer.

Hyperactivity/ADHD is being diagnosed more often in American school children and these children are more often treated with stimulant medication than in the past. Large-scale studies show that 1.3 to 7.3 percent of school age children may be taking stimulants to manage behavior problems that include impulsiveness, inattention and social aggressiveness. Approximately 74 to 97 percent of children treated respond positively to stimulant medication with marked reductions in problem behavior and increased task persistence, work productivity, working memory and fine motor speed and coordination.

The question has been raised, however, whether or not children who take these stimulant medications become sensitized to them, increasing their risk of substance abuse in later life.

The Medical College study used a group of 158 children referred to a child neuropsychology service at Children's Hospital specializing in treating hyperactive children matched with a control group of 81 from the Milwaukee community. The children ranged in age from four to 12 years. The hyperactive children were given standard tests used to diagnose ADHD and the vast majority were having problems both at school and at home.

The children were followed-up twice, once at adolescence (mean age 15 years) and again in young adulthood (mean age 21 years). At both follow-ups, parents of the subjects were also interviewed to get a clearer picture of drug use. Parents of the ADHD group were asked about the length of time their children were treated with medication and whether or not it had been given during high school. Both parents and children were specifically asked if the subject had ever used any of the following drugs: cigarettes, alcohol, marijuana, hashish, cocaine, heroin, hallucinogens and unprescribed stimulants, sedatives or tranquilizers.

Once the data was gathered, the ADHD group was subdivided into those who had and had not been treated with stimulants. A variety of different statistical methods were used to compare the non-ADHD group, the ADHD group that was untreated and the ADHD group that was treated.

The statistics, with one small exception, showed no association of stimulant medication use with later drug abuse. The analysis also showed no association with the length of time stimulant medication was used and later risk of substance abuse.

"One might expect that the longer children had stayed on stimulants, the greater their risk for sensitization," said Dr. Fischer. "This did not occur in our study."

The one exception was a small increased risk for trying cocaine once in treated children during high school. "We believe there are good reasons from other results in this study to pose strong reservations about that conclusion," Dr. Fischer said. "Neither childhood nor high school stimulant treatment status were associated with greater risk for cocaine dependence or abuse - only with ever having used cocaine once. Associating with drug-using peers in high school may explain that greater risk."

---Medical College of Wisconsin