Researchers Use fMRI to Show Brain Differences in Children with ADHD

Weili Lin, PhD

Researchers from the University of North Carolina School of Medicine have imaged the neural activity analogues to cognitive flexibility to discover differences in the brain activity of children with ADHD and those without. Led by the study’s senior author Weili Lin, PhD, scientists documented a significant decrease in neural flexibility across the entire brain of children with ADHD and throughout sub-networks considered crucial to cognitive flexibility. Their findings, recently published in the journal Molecular Psychiatry, could help doctors diagnose children with ADHD and monitor the severity of the condition and treatment effectiveness.

Multitasking is a key functional skill, and it involves something called cognitive flexibility – the ability to smoothly switch between mental processes. Some people are more cognitively flexible than others. It’s just the luck of the genetic draw in some ways, though we can improve our cognitive flexibility once we realize we’re being inflexible. It’s part of executive function, which includes accessing memories and exhibiting self control. Poor executive function is a hallmark of ADHD in children and adults.

When we’re cognitively inflexible, we can’t focus on some of the tasks in front of us. In adults but especially in children, such cognitive inflexibility can wreak havoc with an individual’s ability to learn and accomplish tasks.

UNC scientists Dr Lin, director of the UNC Biomedical Research Imaging Center (BRIC), wanted to find out what’s happening throughout the brain when executive function, particularly cognitive flexibility, is off line. Dr Lin and colleagues used functional magnetic resonance imaging (fMRI) to study the neural flexibility of 180 children diagnosed with ADHD and 180 typically developing children.

“We observed significantly decreased neural flexibility in the ADHD group at both the whole brain and sub-network levels, particularly for the default mode network, attention-related networks, executive function-related networks, and primary networks of the brain involved in sensory, motor and visual processing,” said Dr Lin, the Dixie Boney Soo Distinguished Professor of Neurological Medicine in the UNC Department of Radiology.

The researchers also found that children with ADHD who received medication exhibited significantly increased neural flexibility compared to children with ADHD who were not taking medication. Children on medication displayed neural flexibility that was not statistically different from the group of traditionally developing children.

Lastly, the researchers found that they could use fMRI to discover neural flexibility differences across entire brain regions between children with ADHD and the traditionally developing children.

“And we were able to predict ADHD severity using clinical measures of symptom severity,” Lin said.  “We think our study demonstrate the potential clinical utility of neural flexibility to identify children with ADHD, as well as to monitor treatment responses and the severity of the condition in individual children.”

Other authors of the paper are first author Weiyan Yin, Tengfei Li, Jessica Cohen, Hongtu Zhu, Ziliang Zhu – all of UNC-Chapel Hill – and Peter Mucha, formerly of UNC and now at Dartmouth University. The National Institutes of Health, Autism Speaks, the Stavros Niarchos Foundation, the Leon Levy Foundation, and an endowment from Phyllis Green and Randolph Cowen funded this research.