The longitudinal study, which spanned 23 years, was led by Russell Barkley, Ph.D., and Mariellen Fischer, Ph.D. Their findings concurred with those of 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, had found an increased risk of cocaine use later in life by children treated with stimulants, and the current study was designed in part to test that finding.

"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 Fischer.

The disorder is being increasingly diagnosed 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 who are so treated respond positively with marked reductions in problem behavior and increased task persistence, work productivity, working memory, and fine motor speed and coordination.

The current study evaluated a group of 158 children who had been referred to a child neuropsychology service at a university hospital matched with a control group of 81 children from the same city. The children ranged in age from 4 to 12 years at baseline. The hyperactive children were given standard tests to obtain diagnosis, and the vast majority was having problems both at school and at home.

The children were re-evaluated twice, once at adolescence (mean age 15 years) and again in young adulthood (mean age 21 years). At both follow-up evaluations, parents were also interviewed to get a clearer picture of drug use. Parents of the pediatric patient 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, or unprescribed stimulants, sedatives, or tranquilizers.

After the data were gathered, the patient group was subdivided into subjects who had and subjects who had not been treated with stimulants. A variety of different statistical methods were used to compare the control group, the patient group that was untreated and the patient group that was treated with stimulants.

The statistics, with one small exception, showed no association of stimulant medication use with later drug abuse. The analysis also showed no association between duration of stimulant medication use and later risk of substance abuse.

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

The one exception was a small increased risk for trying cocaine once by treated patients while in high school. "We believe there are good reasons from other results in this study to pose strong reservations about that conclusion," 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."