Taking medication for attention deficit/hyperactivity disorder (ADHD) as a child does not increase — or decrease — the risk for later addiction or alcoholism, according to a new review of the research.
The research may help reassure parents who are concerned about the controversy over the use of medications to treat the disorder, which is now diagnosed in 11% of all schoolchildren. The condition is widely seen as being over-diagnosed, with a rate that has increased 3% to 6% every year between 2000 and 2010 — accompanied by a worrying rise in medication use.
The review, which was published in JAMA Psychiatry, included over 2,500 participants in 15 different studies. Whether the drug in question was alcohol, cocaine, marijuana or nicotine and whether the study looked at experimentation or addiction, researchers found no overall difference in risk related to ADHD medication. The most commonly used ADHD medications are stimulants, typically Ritalin (methylphenidate) or Adderall (a mixture of amphetamines).
“The best evidence to date seems to suggest that treatment with stimulant medication has no substantial role in increasing or decreasing risk for the development of alcohol and drug problems,” says Steve Lee, a co-author of the study and associate professor of psychology at the University of California in Los Angeles.
“Stimulants did not contribute to substance abuse, which is one of the major concerns of parents whenever you are starting a child on medication,” says Dr. Joe Austerman, a psychiatrist at the Cleveland Clinic’s Children’s Hospital, who was not connected with the study.
The question of whether stimulants, which can be addictive themselves, affect addiction risk in ADHD has long been a difficult one. For one, ADHD itself is linked with a greatly increased risk for all types of addictions. Secondly, there are compelling reasons to predict either positive or negative effects.
On the concerning side, some animal research suggests that early exposure to such medications could reduce the capacity to experience pleasure, by affecting the development of the brain’s dopamine systems. Alternatively, it could increase a capacity for desire for the drug, which could be re-awakened in adolescent experimentation. “Early in development, we know that brain structure is changing in immense ways and it could be that at one point in development or in certain brains, [children] are more or less reactive [to the brain effects of the drug],” says Lee. “That could be one mechanism for evidence of a ‘sensitization’ effect, where they would [later] enjoy it more.”
On the other hand, there are reasons to believe that medication would lower addiction risk by reducing stress: a child who does better in school and with peers while on medication seems far less likely to turn to illicit drugs for relief. “As far as being protective, that’s a bit more intuitive,” says Lee. “It might improve attention and functioning and may improve relationships with peers, parents and academics.”
One study did show that the earlier children started taking medication, the lower their risk for drug problems — suggesting that the social explanation may be more powerful, but there is not yet enough data on timing and especially on use in the youngest children.
And the only previous meta-analysis of the data, published in 2003, pointed in that direction as well. It suggested that medication reduced addiction risk by at least 40% in participants followed into adulthood. But studies published since then have had conflicting results, with some even suggesting that children who take medication are at increased risk. Moreover, two of the authors of that review were later disciplined by Harvard for taking millions of dollars in pharmaceutical industry funding without disclosing it.
“The [new review] was funded by the National Institute on Mental Health and [the authors] didn’t have pharmaceutical company involvement,” says Austerman, “It was more comprehensive and done with much higher fidelity so I feel more confident in citing it as a resource.”
The review was also limited by the fact that the children who take medication are not randomly assigned to do so. “The most common reason parents seek help is not because of the symptoms of ADHD,” Lee says. “It’s all of the problems that are consequences of these [symptoms] like academic failure or, My child can’t get a playdate.” Consequently, the children who take medication are likely to have the most severe cases. This would actually mean that the research underestimates any protective effects of the medication.
For girls, the review did suggest that medication could protect against addiction — but because this was based largely on one study and most of the others included far more boys, the authors do not see it as conclusive. “I do believe there’s going to be a gender difference,” Lee says, based on the fact that such differences are seen in virtually all psychiatric disorders.
Because of the possibility of misdiagnosis, Austerman suggests that parents who think that their children may have ADHD get comprehensive testing from an expert specialist, not their regular pediatrician. This is especially true for children who are among the youngest in their class: research shows they are far more likely to be diagnosed when they really are simply acting their age. Frequent monitoring to ensure the right dose and continued need for medication is also recommended. “For the majority, symptoms are reduced to the point that almost two-thirds of patients don’t need medication into adulthood,” he says.
But he notes that the research is far from definitive. As data across addiction shows, simply being exposed to a drug does not determine whether people will develop substance misuse problems.