Methylphenidate—better known by its brand name, Ritalin—has long been a popular and controversial drug. It treats attention deficit hyperactivity disorder, or ADHD, diagnoses of which have risen sharply over the past decade. In 2013, four percent of American teenage boys and two percent of American teenage girls told surveyors that they had taken drugs for ADHD sometime in the past month. Now, ADHD drugs rank alongside antidepressants as the most commonly used psychiatric medications among American teens. Meanwhile, many American parents seem to struggle with their decisions to medicate their kids, worrying about how difficult it can be to draw a bright line between behavior that's restless, but "normal," and behavior that's worthy of treating with drugs.
A new review of the best available evidence adds some important data to the debate. Scientists have conducted perhaps hundreds of randomized controlled trials—considered the "gold standard" of medical evidence—on methylphenidate's effectiveness in kids with ADHD. Yet even these randomized controlled trials had systematic flaws, argues Ole Jakob Storebø, a clinical psychologist who conducts research for Region Zealand in Denmark. Storebø led an international team of scientists in rigorously reviewing the available trials. The team found "the quality of the evidence was very low," according to a report published yesterday by the Cochrane Collaboration. As a result, it's unclear how much methylphenidate really helps. At best, Storebø's team writes, "Methylphenidate might improve some of the core symptoms of ADHD—reducing hyperactivity and impulsivity and helping children to concentrate."
All this means that it should now be an even harder decision to start a kid with ADHD on methylphenidate, Storebø writes to Pacific Standard in an email. "There is more uncertainty to factor in to balancing the benefits and risks," he says.
What does this mean for doctors who work with kids with ADHD?
Clinicians need to weigh what we now believe to be an uncertain degree of benefit against the many adverse events that are known to be associated with methylphenidate, such as appetite suppression and sleep difficulties. The general perception of methylphenidate as an effective drug for all children with ADHD seems out of step with the new evidence.
Careful monitoring of both benefits and harms in children medicated in this way will be important. If there is little or no apparent benefit through reduced ADHD symptoms in children taking a well-monitored, carefully titrated dose, consideration should be given to discontinuing it, especially if harmful side effects are present.
How much do we know about methylphenidate's side effects?
We know very little about the long-term effects or harms as most of the trials in our review did not measure outcomes beyond six months. The risk of rare, serious adverse events seem low over the short duration of follow-up of the trials that reported on harms, but in general there was inadequate reporting of adverse events in many trials.
[Editor's Note: Storebø's team defined "serious adverse events" as hospitalizations and life-threatening conditions. It's already well known that methylphenidate can give some kids "non-serious" side effects such as sleep problems and reduced appetite. There has been some debate about whether methylphenidate is able to cause sudden deaths from heart problems in kids, but a recent study of more than 1.2 million kids found no association between the drug and heart problems. Still, the Food and Drug Administration advises that kids with pre-existing heart problems don't take stimulant drugs like methylphenidate.]
What about kids who are already taking methylphenidate for ADHD?
If they do not have any adverse event on the one-child level, it's important to continue giving the medication. Clinicians need to be mindful of the consequences of stopping methylphenidate in those children whose ADHD symptoms are lower, have improved general behavior, and improved quality of life, as long as they do not also suffer from the adverse effects of medication.
I was surprised to learn that you found poor quality evidence for methylphenidate. Were you surprised?
Yes, it was surprising to me. I definitely believe this must be very surprising to other doctors who work with ADHD.
What kind of questions about methylphenidate would you want to see answered next?
There might be many other ways to investigate supporting young people with ADHD. For example, research could explore whether more support within school settings is warranted, or teaching them in a way that takes into consideration their difficulties in maintaining focused attention.
This interview has been edited for length and clarity.