November 19, 2019
There are no structural differences between the brains of people with and without ADHD. However, ADHD brains do experience elevated “noise” in the signal between their sensory and cognitive regions, which explains why the neural pathways in people with ADHD do not always work effectively and sometimes send erratic messages. These are the findings from a 20-year-long study of individuals with chronic ADHD published recently in the journal Molecular Psychiatry.1
Data was collected from 80 adults who had been diagnosed in childhood with attention deficit hyperactivity disorder (ADHD or ADD), had no psychiatric comorbidities, and had never been treated with medicine. MRI scans were used to create virtual maps of brain pathways with the intention of pinpointing roadblocks in “neurological highways.” Participants with chronic ADHD were compared to a control group of 123 individuals without ADHD.
While structural connectivity didn’t significantly differ between groups, those with ADHD did display a reduced structure-function coupling in feeder connections linking the brain’s hubs with peripheral regions. Specifically, lower structure-function coupling — and faulty communication between these areas of the brain — was associated with increased ADHD symptoms.
Lead researcher and head of the Clinical Brain Networks team at QIMR, Dr Luca Cocchi, explained: “It’s like when a loudspeaker is not working properly and emits a lot of static, making it harder to understand what is being said.”2
Medication continues to be the suggested best treatment for ADHD, but these findings open the door for new interventions, specifically ones that attempt to reduce the “noise” in ADHD brains.
1 Hearne, L.J., Lin, H., Sanz-Leon, P. et al. “ADHD symptoms map onto noise-driven structure–function decoupling between hub and peripheral brain regions.” Mol Psychiatry (2019) doi:10.1038/s41380-019-0554-6
2 Layt, Stuart. “Top minds pinpoint ADHD cause by thinking big over 20 years.” Brisbane Times (Nov. 2019) https://www.brisbanetimes.com.au/national/queensland/top-minds-pinpoint-adhd-cause-by-thinking-big-over-20-years-20191031-p5369r.html