Fran Lowry

November 29, 2011

November 29, 2011 (Chicago, Illinois) — Functional magnetic resonance imaging (fMRI) scans reveal that children with attention deficit hyperactivity disorder (ADHD) have disturbances in certain functions of the brain, researchers reported here at the Radiological Society of North America 97th Scientific Assembly and Annual Meeting.

The finding, from a study of 20 children with ADHD and 15 healthy children without the disorder, provides more evidence that there might be a neurological component to the disorder, lead investigator Xiaobo Li, PhD, from the Albert Einstein College of Medicine in New York City, told Medscape Medical News.

"Their brains may be wired differently; ADHD may not just be all behavior, as people have thought," Dr. Li said.

Dr. Xiaobo Li

In the study, Dr. Li and her group performed fMRI on the children with ADHD (mean age, 10.8 ± 2.1 years) and the slightly older control children (mean age, 12.5 ± 2.3 years). While undergoing fMRI, the children engaged in a test of sustained attention in which they were shown a set of 3 numbers and then asked whether subsequent groups of numbers matched the original set.

The fMRI produced a brain activation map that showed which regions of the brain became activated when the child performed the task; this pattern was then compared in the ADHD and control children.

The researchers found that compared with the control children, the children with ADHD showed abnormal functional activity in several regions of the brain that are involved with processing visual attention information. They also found that communication among the brain regions within this visual attention-processing pathway was disrupted in the children with ADHD.

In spite of these differences, the children with ADHD achieved the same accuracy on the test (85%) as the control children.

"The test required a very intensive, continuous attention load related to brain activity, and was quite difficult. This means that even children with ADHD can perform the task properly, but the way their brains function while they are doing the task is different," Dr. Li said. "Behaviorally, they can successfully do something, but they use somewhat different strategies to solve the problem."

Medscape Medical News invited Carol Rumack, MD, from the University of Colorado School of Medicine in Denver, to comment on this study.

"This is a small study, but the concept is good," Dr. Rumack said.

Pediatricians and pediatric radiologists worry that too many children are being labeled with ADHD and being given methylphenidate (Ritalin) and other drugs when, in fact, they might not have ADHD at all, she explained.

"It would really be good if we could have a specific diagnosis and get some of them off of [methylphenidate]. They may have a different disease; they may just be restless because they're bored. Having an objective way to look at their brain activity is definitely useful."

Dr. Li said that it was too soon to apply these results widely for diagnostic or treatment purposes, but she intends to continue this line of research. Right now, her hope is that the results from this study will help clinicians find a stable biomarker of ADHD.

In addition, fMRI could provide a way to monitor how well ADHD medication is working in a particular child, she suggested. "Detecting changes that occur with medication could be a way to tell clinicians whether their treatment is or is not sufficient," she said.

Dr. Li and Dr. Rumack have disclosed no relevant financial relationships.

Radiological Society of North America (RSNA) 97th Scientific Assembly and Annual Meeting: Abstract S101AB. Presented November 28, 2011.

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