ADHD drugs may boost arousal more than attention : Shots

A picture of the brain shows that when stimulants increase arousal, they calm (darker colors) various parts of the brain.

Benjamin Kay/Washington University in St. Louis

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Benjamin Kay/Washington University in St. Louis

Scientists are updating their view of how drugs like Adderall and Ritalin help children with attention deficit hyperactivity disorder stay on task.

The latest evidence is a study of thousands of adolescent brain scans that confirms previous indications that stimulant medications have little direct impact on the brain networks that control attention.

Instead, the drugs appear to activate networks involved in alertness and anticipation of pleasure, scientists say. report in the magazine Cell.

“We think it’s a combination of excitement and reward, that kind of punch, that really helps kids with ADHD when they take this medication,” says Dr Benjamin Kaypediatric neurologist at Washington University School of Medicine in St. Louis and lead author of the study.

The findings, along with those from smaller studies, support a “change in thinking about the effect of stimulants on people,” says Peter Manza, a neuroscientist at the University of Maryland who was not involved in the research.

The new research analyzed data from the Adolescent Brain Cognitive Development Studya federally funded effort that includes brain scans of nearly 12,000 children. About 4% of these children had ADHD when they participated in the study, and almost half of them were taking a prescription stimulant.

About 3.5 million children In the United States, they are taking ADHD medication, and their numbers are increasing.

Drugs and brain networks

The brain scan data included a type of MRI that measures brain activity when a person is at rest. This allowed Kay and a team of scientists to see which areas of the brain became more active in response to the drugs.

Kay expected to find a lot of activity in areas that allow a person to control what they pay attention to.

“What I found is that these are the least affected parts of the brain,” he says.

Instead, the drugs stimulate areas that help people stay awake and alert, as well as areas that anticipate a pleasant reward.

This dual effect appears to occur because stimulants like Ritalin and Adderall increase the levels of two different chemicals in the brain, says Dr. Nico Dosenbach, lead author of the paper and professor at the University of Washington.

The first chemical is norepinephrine, which prepares the body and brain for action.

The study found that this “fight or flight” response counters the usual cognitive declines associated with lack of sleep on cognitive performance. Lack of sleep is a problem for many adolescents, but especially those with ADHD.

The second brain chemical is dopamine, which plays an important role in the brain’s reward system. And increased dopamine levels can help children with ADHD feel more positive about mundane tasks like homework.

Usually the brain’s expectation is: “It’s going to be terrible, it’s going to be boring,” says Dosenbach. “Dopamine can make you more tolerant because you feel a mild, low-level reward.”

It’s still too early to know if that’s what’s happening, Manza said. But he agrees that stimulants do something in the brain that helps children with ADHD do things like their homework.

“They don’t find math problems very interesting, but after a dose of Ritalin it might seem more interesting to them,” he says, “and so they are willing to persevere and complete the task.”

Brain scans before drugs?

The new study’s results should not undermine clinicians’ confidence in the effectiveness of stimulants for ADHD, Kay says. But they suggest it is important to rule out factors such as lack of sleep before resorting to medication.

“This was a very personal article for me because I prescribe these medications all the time,” says Kay.

The findings also suggest that brain scans could potentially help determine whether a child is likely to benefit from drug treatment, Manza says.

“Stimulants don’t work for everyone,” he says, “so we need to better target the individuals who need them.”

MRI scans may one day even offer a better way to diagnose ADHD, Manza says. It’s absolutely necessary, he says, at a time when more and more children and young adults are being told they have the disease and should take medication.