By finding distinct patterns of activity in the brains of children with ADHD, researchers hope to someday develop an early test for the disorder.
The findings were presented here at the annual meeting of the Radiological Society of North America.
Pattern of Brain Activity Different in Children With ADHD
Functional MRI allows doctors to see how the brain reacts to different types of activity.
While undergoing the brain scans, the children took a series of tests in which they were shown a set of three numbers and then asked whether additional sets matched the original numbers.
The test requires the children to pay attention and visualize, remember ,and compare the numbers, says study leader Xiaobo Li, PhD, assistant professor of radiology at the Albert Einstein College of Medicine in New York City.
"What we found," she tells WebMD, "is that the pattern of brain activity for processing visual attention information looks a little different in children with ADHD."
Specifically, the scans of children with ADHD showed less activity in brain regions involved in visual attention and working memory, Li says.
Much Work Remains
If the same pattern of brain activity is confirmed in other studies of children with ADHD, it could serve as an indicator for the disorder, Li says. Doctors, then, could use functional MRI scans to look for the pattern of activity as soon as, or even before, symptoms develop, she says.
But first, researchers have to make sure the pattern is distinct to ADHD and not shared by other childhood disorders, Carol Rumack, MD, professor of radiology and pediatrics at the University of Colorado Anschutz Medical Campus in Aurora, tells WebMD.
Plus, it would be prohibitively expensive to use functional MRI scans as a screening tool for thousands of youngsters, she says. A scan can cost $3,000 to $5,000, she says, though the price tag could come down in the future.
But research like this is important for unraveling how the brain works in people with ADHD, Rumack says. "It would be great to have a way to diagnose ADHD."
Currently, there is no single test for the disorder. If medical tests rule out other conditions, doctors usually diagnose the condition based on symptoms brought to their attention by parents, who often hear about them from teachers.
The symptoms -- which include inattention, hyperactivity, and impulsivity -- can simply be signs a child is bored in school, Rumack says.
As a result, many children are incorrectly labeled with ADHD -- and given drugs like Ritalin when they don't need them, she says.
ADHD is a common childhood disorder, affecting an estimated 5% to 8% of school-aged children.
Li says much of the research conducted on ADHD has focused on the impulsivity component of the disorder.
The new study, she says, is one of the first to look at inattentiveness in ADHD.
These findings were presented at a medical conference. They should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.