Cortical abnormalities in children and adolescents with attention-deficit hyperactivity disorder

Results of structural brain imaging studies of patients with attention-deficit hyperactivity disorder have shown subtle reductions in total brain volume and in volumes of the right frontal lobe and caudate nucleus. Although various conventional volumetric and voxel-based methods of image analysis have been used in these studies, regional brain size and grey-matter abnormalities have not yet been mapped over the entire cortical surface in patients with this disorder. We aimed to map these features in patients with attention-deficit hyperactivity disorder.

We used high-resolution MRI and surface-based, computational image analytic techniques to map regional brain size and grey-matter abnormalities at the cortical surface in a group of 27 children and adolescents with attention-deficit hyperactivity disorder and 46 controls, who were group-matched by age and sex.

Abnormal morphology was noted in the frontal cortices of patients with attention-deficit hyperactivity disorder, with reduced regional brain size localised mainly to inferior portions of dorsal prefrontal cortices bilaterally. Brain size was also reduced in anterior temporal cortices bilaterally. Prominent increases in grey matter were recorded in large portions of the posterior temporal and inferior parietal cortices bilaterally.

The frontal, temporal, and parietal regions are heteromodal association cortices that constitute a distributed neural system, which subserves attention and behavioural inhibition. We have identified region-specific anatomical abnormalities in cortical components of attentional systems, which may help better account for the symptoms of attention-deficit hyperactivity disorder.