fMRI Shows Functional Brain Abnormalities in Children with ADHD

CHICAGO - Using functional magnetic resonance imaging (fMRI) researchers identified abnormalities and disrupted pathways in brains of children with attention deficit hyperactivity disorder (ADHD), according to a study presented at RSNA Monday.

"Diagnosing ADHD is very difficult because of its wide variety of behavioral symptoms," said lead researcher Xiaobo Li, PhD, assistant professor of radiology at the Albert Einstein College of Medicine in New York. "Establishing a reliable imaging biomarker of ADHD would be a major contribution to the field."

ADHD starts in childhood, affecting about 5 percent to 8 percent of school-aged children. Symptoms include hyperactivity, impulsivity and inattention outside the normal range for the child’s age and development.

As the disorder continues into adulthood, it costs the U.S. an estimated $36 to $54 billion each year, said Li. Rates of parent-reported cases are up, according to the Centers for Disease Control and Prevention.

Current diagnosis looks at behaviors, but Li said brain markers offer more accurate diagnosis criteria. The neurobiological foundation of this disorder has not been well studied, she said.

Compared to the control group, the children with ADHD showed abnormal brain activity in parts of the brain responsible for processing visual attention information. Researchers also found disrupted communication among brain regions in the children with ADHD.

"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," Li said.

The study compared 18 typically developing children to 18 children diagnosed with ADHD (9 to 15 years old). While undergoing an fMRI the children were asked to perform certain tasks for five minutes. Researchers looked at 16 regions for functional connectivity and took group average to get group differences.

Li said most research on ADHD focuses on impulsivity, but this gives an incomplete understanding of the disorder.

"Inattention is an equally important component of this disorder," she said, "and our findings contribute to understanding the pathology of inattentiveness in ADHD."