ADHD Drugs Do Not Increase Risk for Later Substance Abuse

Stimulant medications used to treat attention deficit hyperactivity disorder (ADHD) in children do not lead to substance abuse later in their lives, according to a Medical College of Wisconsin study released in 2003 and published in the journal Pediatrics.

The research findings are among the most recent in a growing body of evidence, supported by results from ten previous studies elsewhere, indicating that ADHD drugs do not "sensitize" children to drug use in general.

"We found that maintenance on stimulant medication in childhood does not increase the risk for substance abuse in adolescence and young adulthood in individuals who have ADHD," said Mariellen Fischer, PhD, Medical College Professor of Neurology and one of the principal investigators for the study.

Most research suggests that people with ADHD who are not treated are actually at increased risk for substance abuse compared to people without ADHD, Dr. Fischer said, in great part because ADHD impairs coping abilities, affects self esteem and emotional stability, and diminishes focus and capacity to learn and perform both academic and life skills.

Since stimulant drugs help control ADHD symptoms, it appears they also provide some protection against substance abuse. Dr. Fischer noted that the "sensitization hypothesis" connecting the use of prescribed drugs to substance abuse is by no means proven, and not just as it relates to ADHD drugs.

"There is some evidence for that hypothesis in animals," said Dr. Fischer. "There is no evidence for that hypothesis in humans. The research that has been done in humans that has appeared to support that hypothesis is all methodologically flawed and fails to take into account some of the variables that we in fact controlled for in our research study."

Study Finds No Association
"There is no evidence that taking medication for ADHD makes you more likely to take illicit drugs later on in life," said Dr. Fischer. "There is no evidence that it makes you think, 'Oh, I'll cure a problem by popping a pill,' and there's no evidence that taking the medication somehow sensitizes your brain to make it more likely to become addicted to substances if you happen to try them later on in life."

The Medical College study took 13 years to complete, beginning with two groups of subjects ranging in age from 4 to 12 years. Researchers compared 158 children referred to a neuropsychology service for hyperactive children at Children's Hospital of Wisconsin to a control group of 81 children from Milwaukee. Standard tests were used to diagnose ADHD in the hyperactive children.

In follow-ups conducted when the children reached a mean age of 15 years and again when they were at a mean age of 21, the study participants and their parents were interviewed and asked if the subjects had ever used any alcohol, marijuana, cigarettes, cocaine, hallucinogens, hashish, or unprescribed stimulants, tranquilizers or sedatives.

After determining which of the ADHD children had been treated with stimulants and how long they had been on these medications, a statistical analysis of the data compared later drug use among three groups: children who did not have ADHD, children with ADHD who had not been treated with stimulants, and children with ADHD who had been treated with stimulants.

No association was found between the use of stimulant drugs to treat ADHD and later drug use, even for the children who had been on stimulants for relatively long periods of time. The only exception was a slight increased risk for treated ADHD children to try cocaine, but just once, while in high school.

Dr. Fischer said that that there are "strong reservations" about that conclusion, however, as subsequent analyses showed that the elevated risk was a function of severity of the ADHD and associated conduct disorder rather than the stimulant medication treatment.

More Cases, More Prescriptions
As the number of children diagnosed with ADHD has grown, so has the use of drugs to treat them. Studies reported by the National Institutes of Health show that as many as 7.3% of school children may now be taking stimulants to manage ADHD-related symptoms.

Those symptoms include impulsivity, overactivity or difficulty controlling activity so that it is appropriate to circumstances, and inability to focus attention.

Stimulants have been the most commonly prescribed drugs used to treat ADHD. In the majority of cases, Dr. Fischer said, children with ADHD benefit significantly when stimulants or other appropriate medications are incorporated into treatment. The drugs can diminish impulsive behaviors, improve attention to tasks at hand, and aid working memory and in some instances coordination and motor control.

Given the expanding role of ADHD drugs, accurate assessment of risks related to their use is important to more and more parents and others who ponder treatment options for children in their care.

"Having ADHD increases the risk for substance abuse," said Dr. Fischer. "That's very clear. What's interesting is that the gateway drug is not marijuana, as many people might think. It's nicotine.

"I tell parents that there is no research evidence that using the medications to treat ADHD places their children at risk for later substance abuse and that there is evidence that the medications actually help to decrease the risk for substance abuse."

Dan Ullrich
HealthLink Contributing Writer

For more information on this topic, see the HealthLink articles One in Every Classroom: Kids with ADHD Struggle to Make the Grade and Newly-Available Drug Shows Promise for ADHD Symptoms.

MCW Health News presents up-to-date information on patient care and medical research by the physicians of the Medical College of Wisconsin.