Not a cure-all after all. Photographer: JB Reed/Bloomberg
Not a cure-all after all. Photographer: JB Reed/Bloomberg

Over the past 20 years, mental disabilities have overtaken physical disabilities as the leading limitation on children's activities. Today, attention deficit hyperactivity disorder is three times more likely than asthma to disable an American child.

An often difficult question for parents is whether to put their child with ADHD on either Ritalin or Adderall, the most common drug treatments for hyper and impulsive behaviors. Increasingly, the answer has been yes. In 2011, according to the U.S. Centers for Disease Control and Prevention, more than 6 percent of American children ages 4 to 17 were taking ADHD drugs.

Ritalin and Adderall can be essential, life-changing treatments for many children. But for some, the benefits are not so clear. In a recent study, we and our colleague Lauren Jones examined the short- and long-term effectiveness of stimulants such as Ritalin in children. We looked at a sample of 8,643 Canadian children (1,654 of them in Quebec) before and after the 1997 expansion of drug insurance in Quebec, which made prescriptions more affordable. Within a decade of this expansion, 9 percent of children in Quebec were using stimulants, compared with 5 percent in the rest of Canada. By 2007, 44 percent of Canada’s ADHD prescriptions were being written in Quebec, which has a little more than 20 percent of Canada’s population.

One might have anticipated that easier access to medication would lead to improved health and, ideally, better educational performance. Instead, we found evidence that the children using stimulants fared slightly worse. After the insurance expansion, the Quebec children experienced more depression and anxiety -- problems that could be side effects of stimulant medication. Meanwhile, there was little evidence of any benefits for the children's schooling. On the contrary, we found their chances of progressing through school without repeating a grade to be somewhat lower than they had been before the insurance expansion and lower than those of children in the rest of Canada. Their probability of high school graduation likewise declined a bit.

After the insurance policy change, more boys than girls started using stimulants, including many whose initial ADHD symptoms were minimal. Among girls, increased stimulant use was more concentrated among those with high initial levels of ADHD symptoms. Even so, the added stimulant use among girls was associated with more symptoms of anxiety and depression, falling math scores, and a decline in the probability they would go on to get a post-secondary education.

How is it possible that more ADHD medication could lead to worse academic performance? One possibility is that a child given stimulants is more subject to the stigma of being labeled with ADHD or being placed in special education. A second possibility is that medication becomes a substitute for other needed cognitive and behavioral interventions. By making children less disruptive, ADHD medication could decrease the attention they receive in the average classroom, so that teachers don't refer them for other services that would help them learn. A third possibility is that the medication itself has ill effects on emotional well-being and learning, especially if it's not taken properly or in the right dosage.

Our findings suggest there is reason for concern over increased use of medication for ADHD in the U.S., Canada and other countries. We should not be so quick to medicate children, or to assume that once medicated, they no longer need other help.

To contact the writers of this article: Janet Currie at jcurrie@princeton.edu and Mark Stabile at mark.stabile@utoronto.ca.

To contact the editor responsible for this article: Mary Duenwald at mduenwald@bloomberg.net.