Kids with ADHD have some smaller than normal brain regions, study finds

Children with attentiondeficit hyperactivity disorder have several brain regions that are slightly smaller than usual, more evidence that the disorder should be considered a neurological condition, a new study says.

The study, the largest review of ADHD patients’ brain scans ever conducted, might also provide clues for developing new treatments.

“If you know what region of the brain is involved in ADHD, you could possibly target that part with medication,” said Martine Hoogman of Radboud University in the Netherlands, the lead author.

ADHD causes inattention, hyperactivity and impulsivity, although a given person may not show all those traits.

Hoogman and colleagues analyzed MRI scans for more than 3,200 people in nine countries aged four to 63, of whom 1,713 had ADHD. They found that the brains of children with the condition were slightly smaller in five regions, including those that control emotions, voluntary movement and understanding. The scientists reviewed one scan per person and found no effect from ADHD medications.

Hoogman said the findings support previous theories that the brains of people with ADHD may develop more slowly but that those differences are mostly wiped out by the time children grow up.

The study was paid for by the National Institutes of Health and was published online last week in the journal, Lancet Psychiatry.

Other experts described the findings as interesting but said there wasn’t enough information to link the brain differences to behavioural problems seen in people with ADHD.

“The study confirms that there are structural differences in the brains of people with ADHD, but it doesn’t tell us what they mean,” said Graham Murray, of at Cambridge University, who was not part of the research.

“Having less brain in several regions sounds bad but it’s not as simple as that,” he said, pointing out that decreased brain matter can sometimes be beneficial — like in teenagers, when the outer cortex of their developing brains becomes thinner as their intellectual capacity grows.

“The brain is very good at adapting. Just because you have less brain volume doesn’t condemn the child to not being able to function well.”