New findings in a large MRI study on ADHD suggest the disorder is more neurological than behavioural.
The study, self-described by its researchers as the largest-ever MRI study on ADHD–indeed, it’s titled Subcortical brain volume differences in participants with attention deficit hyperactivity disorder in children and adults: a cross-sectional mega-analysis–was published Wednesday in The Lancet Psychiatry.
The researchers evaluated more than 3,200 MRI brain scans of participants aged 4-63, comparing 1,713 people with ADHD to a control group.
The study claims that the scans of participants with ADHD collectively showed smaller brain volume, significantly so in five subcortical regions, but also in general. The amygdala and hippocampus, brain regions responsible for emotional processing, were both indicated, surprising the researchers. Crucially, the differences were more marked in children than in adults.
Referring to these visible brain differences, lead author of the study, Dr. Martine Hoogman, said: “These differences are very small — in the range of a few percent — so the unprecedented size of our study was crucial to help identify these. Similar differences in brain volume are also seen in other psychiatric disorders, especially major depressive disorder.”
The authors of the study hope their findings will help readers to reflect on prevailing opinions about ADHD. “The results from our study confirm that people with ADHD have differences in their brain structure and therefore suggest that ADHD is a disorder of the brain,” said Dr. Hoogman. “We hope that this will help to reduce stigma that ADHD is ‘just a label’ for difficult children or caused by poor parenting.”