JUANA SUMMERS, HOST:
Scientists are changing their view of how drugs like Adderall and Ritalin help children with ADHD stay on task. NPR's Jon Hamilton reports on a new study that found the drugs act on brain networks involved in alertness and reward but not attention.
JON HAMILTON, BYLINE: About 3.5 million children in the U.S. take stimulants for attention deficit hyperactivity disorder, or ADHD. Dr. Benjamin Kay, of Washington University in St. Louis, says he finds it puzzling that these drugs actually work.
BENJAMIN KAY: If we're treating predominantly hyperactivity, why would a drug that wakes you up more help with that?
HAMILTON: So Kay, a pediatric neurologist, jumped at the chance to study how these stimulants affect a child's brain.
KAY: This was a really personal paper for me because I prescribe these medications all the time.
HAMILTON: Kay was part of a team that reviewed data from a government study that includes brain scans of nearly 12,000 adolescents. About 4% had ADHD, and nearly half of those children were on a prescription stimulant. Kay says that allowed the team to see which brain areas were affected by the drugs.
KAY: What I expected to find was that the stimulants would act on the parts of the brain that modulate attention. What I actually found was that those were the parts of the brain that were least affected.
HAMILTON: Instead, the drugs stimulated brain areas that help us stay awake and alert. They also activated areas that anticipate a pleasurable reward.
KAY: We really think it's a combination of both arousal and reward - that kind of one-two punch - that really, really helps kids with ADHD when they take this medication.
HAMILTON: The first punch involves norepinephrine, which prepares the body and brain for action. The study found that this response could counteract the effects of sleep deprivation, a common problem in children with ADHD. Dr. Nico Dosenbach, a coauthor of the study, says the second punch seems to help kids overcome another common problem.
NICO DOSENBACH: They're looking at some kind of homework and their brain goes, this is going to be terrible. This is going to be boring. I don't like this, and then you can't stick with it.
HAMILTON: Dosenbach says ADHD drugs seem to limit this negative response by boosting levels of dopamine, a brain chemical that influences motivation and pleasure.
DOSENBACH: It can make you more tolerant because you're feeling a slight sort of low-level, low-key reward.
HAMILTON: Dosenbach says dopamine may also explain why children with ADHD can sit still and focus on an activity that they do find rewarding. He says this behavior even led one dad to conclude that his son was faking ADHD.
DOSENBACH: He was like, well, when I take him hunting, he can sit in a high stand all day long without moving a muscle. But in school, he's bouncing off the walls and leaving the classroom and wandering off the premises.
HAMILTON: Dosenbach suspects hunting simply produced enough dopamine to offset the boy's hyperactivity. The findings appear in the journal, Cell. Neuroscientist Peter Manza, of the University of Maryland, says they show how ADHD researchers are moving away from the idea that stimulants directly improve attention. He says his own work suggests that stimulants are boosting motivation in kids with ADHD.
PETER MANZA: They don't find math problems very interesting, but after a dose of Ritalin it might seem more interesting to them, and so they're willing to persist and finish the task.
HAMILTON: Manza says the study also suggests that brain scans might eventually offer a way to confirm that a child has ADHD and will benefit from drug treatment.
MANZA: Stimulants don't work for everyone, and so we need to better target the individuals who need them and not unnecessarily prescribe them to the individuals who don't need them.
HAMILTON: That's a growing concern as stimulant prescriptions continue to rise.
Jon Hamilton, NPR News.
(SOUNDBITE OF DELICATE STEVE'S "PEACHES") Transcript provided by NPR, Copyright NPR.
NPR transcripts are created on a rush deadline by an NPR contractor. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.
