Analysis of data from the Adolescent Brain and Cognitive Development study has revealed only minor differences in MRI measures of the brain between children with and without ADHD

child with ADHD

Despite several studies finding a variety of abnormalities in cortical and subcortical structures in children with attention deficit hyperactivity disorder (ADHD), a recent study published in The Lancet Psychiatry has revealed very small effect sizes between children with ADHD and their unaffected peers.

The analysis used data from the Adolescent Brain and Cognitive Development study. It included 949 children aged 9–10 years who met the criteria for ADHD and 9,787 who did not. The researchers tested for differences in structural magnetic resonance imaging (MRI) measures of cortical thickness, cortical area, and subcortical volume.

The results revealed fewer significant group differences than expected, with effect sizes ranging from -0.11 to -0.06. There were no significant differences in cortical thickness or subcortical volume, and only 10 of 35 cortical areas, along with estimated total intracranial volume, differed between the groups.

Based on their findings, the authors concluded that in the general population, children aged 9–10 years with ADHD differ only modestly from their unaffected peers on structural MRI measures. Therefore, future clinical trials should incorporate other MRI modalities, novel statistical approaches, or alternative diagnostic classifications, particularly for research aimed at developing ADHD diagnostic biomarkers.

The study’s senior author, Dr Jonathan Posner, Vice Chair of Research in the Deparment of Psychiatry and Behavioural Sciences, Duke University, said: ‘There has been an ongoing debate dating back decades about whether ADHD is in fact a true biological disorder, or if it instead reflects normal variation in attention and related behaviors.

‘While this finding rekindles that long-standing debate, we do believe it is a biological disorder. It can be both—a biological disorder, but also have normal variations within that.

‘It’s important to note that ADHD can be impairing. Treatments help with that. And while we don’t have good evidence of structural differences appearing in MRI scans, that could well speak to the limitations of the technology, not of ADHD being outside of biology.’

This article has been adapted from an article that was originally published on Univadis, part of the Medscape Professional Network.

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