ADHD News & Research

Motor Cortex Physiology Differs in Children with ADHD

In a recent study, children with severe ADHD symptoms showed lower brain engagement and slower reaction time than did their typically developing peers.

July 26, 2019

Children with attention deficit disorder (ADHD or ADD) demonstrate different motor cortex physiology than do their typically developing peers, according to a study published in Neurology1 on July 17. Specifically, the study’s subjects with ADHD exhibited slower response times and significantly less inhibitory signaling to their fingers than did its neurotypical subjects.

In the case-control study, researchers at Cincinnati Children’s Hospital Medical Center compared responses of 66 children diagnosed with ADHD and 65 children selected as typically developing controls. All were right-handed and aged 8 to 12 years. Participants reacted to prompts to control an on-screen race car in a modified version of the Slater-Hammel stop-signal procedure, while receiving non-invasive transcranial magnetic stimulation (TMS) pulses to stimulate the motor cortex.

Response inhibition performance was comparable between the two groups, but compared to their typically developing peers, the ADHD group demonstrated deficient short interval cortical inhibition (SICI) and less task-related up-modulation (TRUM) from rest to action selection. The ADHD group members had slower and more variable “Go” responses and demonstrated 40% less inhibitory signaling to their fingers during the “driving” portion of the exercise and 45% less during the “stopping” portion.

Overall brain engagement was 10% lower within the ADHD group and diminished TRUM and slower reaction time from the state of rest to selecting an action correlated strongly with severity of ADHD symptoms. The results support further research into physiological differences in the brain chemistry of children with and without ADHD symptoms.

View Article Sources

1 Gilbert, Donald L., Huddleston, David A., Wu, Steve W., Pedapati, Ernest V., Horn, Paul S., Hirabayashi, Kathryn, Crocetti, Deanna, Wasserman, Eric M. Motofsky, Stewart H. “Motor cortex inhibition and modulation in children with ADHD” Neurology (July 2019).