NEWS RELEASE, 5/5/99 Ritalin may cause children to smoke early, abuse stimulants as adults, UC Berkeley professor says

By Jacqueline Frost, Public Affairs

BERKELEY--Children treated with stimulant drugs such as Ritalin to control attention- deficit/hyperactivity disorder (ADHD) take up cigarette smoking earlier, smoke more heavily and are more likely to abuse cocaine and other stimulants as adults, according to findings by a University of California, Berkeley, professor. In a report presented to the National Institutes of Health (NIH), Nadine Lambert, director of the School Psychology Program at UC Berkeley's Graduate School of Education, reveals a "significant" relationship between use of central nervous system (CNS) stimulants in childhood and a dependence on tobacco and other stimulants as adults. "This study has provided evidence that childhood use of CNS stimulant treatment is significantly and pervasively implicated in cocaine dependence, in the uptake of regular smoking and in daily smoking in adulthood, as well as in the lifetime use of stimulants and cocaine," Lambert says in her report. Lambert's research is based on an ongoing 26-year study of 492 San Francisco Bay area children, half of whom suffered from some degree of ADHD. The remaining children did not have ADHD. Since a large proportion children with ADHD commonly are treated with Ritalin and similar drugs, she says such findings raise important questions about the risks associated with these treatments. "Ritalin does not cure a child's problems," says Lambert, whose research was supported by the National Institute of Drug Abuse and Tobacco-Related Disease Research Program. "It's a treatment that facilitates functioning, but it's a risk factor for substance use and abuse," she says. "The results of my research indicate that parents should be aware of such risks when considering using such drugs for their children." ADHD is the most common behavioral disorder of childhood, estimated to affect three to five percent of school-age children. Children with ADHD display a range of developmentally inappropriate behaviors including severe problems sitting still, paying attention, concentrating and controlling their impulses. The disorder can cause long term problems in school, at home, at work and in other social interactions. In November, the NIH gathered a group of experts, including Lambert, to testify at a two-day consensus development conference on the disorder. The group's findings were published in a statement, "Diagnosis and Treatment of Attention Deficit Disorder. NIH Consensus Statement 1998," which can be found on the web at: http://odp.od.nih.gov/consensus/cons/110/110_intro.htm. In her 26-year study, Lambert found that the more severe the ADHD, the more likely youngsters would become regular smokers. Ritalin apparently increased the likelihood of cigarette smoking and cocaine abuse. For instance, by age 17, half the teenagers with severe ADHD smoked regularly, compared to only 30 percent of those suffering milder symptoms. And while nearly half of the youngsters treated with Ritalin had become regular smokers by age 17, only 30 percent of those who had never been treated smoked daily. Adult cigarette smokers treated with Ritalin as children were twice as likely to abuse cocaine as those who never smoked or were treated with CNS stimulant drugs, Lambert found. Only two percent of those studied who had never smoked or taken Ritalin were dependent on cocaine as adults, compared to 40 percent among those who both smoked and were treated with CNS stimulants. Lambert says her research suggests two explanations for the higher rates of dependence on tobacco and stimulants among former Ritalin users. First, she says, is a "self-medicating" theory. Persons suffering from severe ADHD symptoms are more likely to become dependent upon tobacco, cocaine and other stimulants, but not depressants such as marijuana or alcohol. This difference suggests they may use the drugs to control their ADHD symptoms, but the disorder itself may compromise their ability to control or self-regulate their drug use and, as a result, they become dependent upon them, Lambert says. Lambert says her research also suggests a "sensitization hypothesis" based on animal studies showing that early exposure to amphetamine and methylphenidate (Ritalin) predisposes rats to the reinforcing impact of cocaine. The same sensitization may occur in humans if exposure to stimulants such as Ritalin predisposes children to the stimulating effects of tobacco, cocaine and amphetamines, Lambert says. "The investigation did not permit definitive conclusions, however, regarding the relative strength of either a sensitization or a self-medicating explanation," she says in her report Lambert's 492 research subjects were selected from a sample of 5,212 kindergarten through fifth grade children attending public, parochial and private schools during the 1973-74 school year in the East Bay region of the San Francisco Bay Area. They and their parents and teachers were interviewed regularly throughout high school and later as young adults. About half of the 492 subjects were hyperactive (ADHD) as children, the remainder were classmates without symptoms who were used as a comparison group. Lambert has written extensively on ADHD and learning and has received numerous honors and awards, including a distinguished service award from the American Psychological Association.