Distributed grey and white matter deficits in hyperkinetic disorder: MRI evidence for anatomical abnormality in an attentional network

Background. Previous neuroimaging studies of children with attention defici t hyperactivity disorder (ADHD) have demonstrated anatomic and functional a bnormalities predominantly in frontal and striatal grey matter. Here we rep ort the use of novel image analysis methods, which do not require prior sel ection of regions of interest, to characterize distributed morphological de ficits of both grey and white matter associated with ADHD. Methods. Eighteen children with a refined phenotype of ADHD, who also met I CD-10 criteria for hyperkinetic disorder (mean age 10(.)4 years), and 16 no rmal children (mean age 10(.)3 years) were compared using magnetic resonanc e imaging. The groups were matched for handedness, sex, height, weight and head circumference. Morphological differences between groups were estimated by fitting a linear model at each voxel in standard space, applying a thre shold to the resulting voxel statistic maps to generate clusters of spatial ly contiguous suprathreshold voxels, and testing cluster 'mass', or the sum of suprathreshold voxel statistics in each 2D cluster, by repeated random resampling of the data. Results. The hyperkinetic children had significant grey matter deficits in right superior frontal gyrus (Brodmann area (BA) 8/9), right posterior cing ulate gyrus (BA 30) and the basal ganglia bilaterally (especially right glo bus pallidus and putamen). They also demonstrated significant central white matter deficits in the left hemisphere anterior to the pyramidal tracts an d superior to the basal ganglia. Conclusions. This pattern of spatially distributed grey matter deficit in t he right hemisphere is compatible with the hypothesis that ADHD is associat ed with disruption of a large scale neurocognitive network for attention. T he left hemispheric white matter deficits may be due to dysmyelination.