MONDAY, Nov. 28 (HealthDay News) -- The brains of children with
attention-deficit/hyperactivity disorder (ADHD) show abnormalities
in certain areas involved with "visual attention," new research
Researchers performed functional MRIs (fMRIs) on 19 children
aged 9 to 15 diagnosed with ADHD and 19 without the disorder while
the children took a test in which they were shown a set of numbers
and then asked to remember whether a subsequent group of numbers
matched the original.
The test requires children to pay attention and stay focused in
order to remember the original set, said lead study author Xiaobo
Li, an assistant professor of radiology at the Albert Einstein
College of Medicine in New York City.
An fMRI is a specialized type of MRI used to measure brain
The scans showed that the kids with ADHD had less activity in
the frontal lobe, parietal lobe and temporal lobe, which is
"consistent with previous studies that showed reduced activations
in those same regions," Li said. Those brain regions have also been
associated with attention and working memory, she added.
Children with ADHD also showed differences in brain connectivity
between regions, including "short-range," "long-range" and
"across-hemisphere" abnormalities, she said.
"What this tells us is that children with ADHD are using partially different functional brain pathways to process this information, which may be caused by impaired white matter pathways involved in visual attention information processing," said Li, who plans to study the ability of children with ADHD to stay focused on auditory information, or what they hear, next.
The research is slated for presentation Monday at the
Radiological Society of North America meeting in Chicago. The data
and conclusions of research presented at medical meetings should be
viewed as preliminary until published in a peer-reviewed
ADHD affects an estimated 5 percent to 8 percent of school-aged
children. Symptoms, which can persist into adulthood, include
inattention, hyperactivity and impulsivity beyond what's normally
seen given a child's age and development.
Though researchers suggested that the brain connectivity
abnormalities could eventually be used as a diagnostic tool for
ADHD, other experts say far more needs to be learned first. That
would include doing studies with more children, and determining
whether the differences in connectivity observed on the fMRI scans
are exclusively seen in kids with ADHD or also in children with
"To suggest that fMRI should be recommended as an initial evaluation of ADHD patients is certainly not justified at this point and there are no immediate clinical recommendations that would come out of this," said Dr. Andrew Adesman, chief of developmental and behavioral pediatrics at Steven and Alexandra Cohen Children's Medical Center in New Hyde Park, N.Y.
Though the findings are "far from being a diagnostic tool, it
does suggest some brain mechanism is associated with the symptoms,"
There is no single test for ADHD. Currently, doctors diagnose
ADHD using information about a child's behavior from parents and
other caregivers and a medical exam to rule out other
"Diagnosing ADHD is very difficult because of its wide variety of behavioral symptoms," Li said. "Establishing a reliable imaging biomarker of ADHD would be a major contribution to the field."
U.S. National Institute of Mental Health has more