Size matters: increased grey matter in boys with conduct problems and callous-unemotional traits.

Brain imaging studies of adults with psychopathy have identified structural and functional abnormalities in limbic and prefrontal regions that are involved in emotion recognition, decision-making, morality and empathy. Among children with conduct problems, a small subgroup presents callous-unemotional traits thought to be antecedents of psychopathy. No structural brain imaging study has examined this subgroup of children. The present study used voxel-based morphometry to compare whole brain grey matter volumes and concentrations of boys with elevated levels of callous-unemotional conduct problems and typically developing boys and explored four a priori regions of interest. sMRI scans were collected from 23 boys with elevated levels of callous-unemotional conduct problems (mean age = 11 years 8 months) and 25 typically developing boys (mean age = 11 years 6 months) selected from a community sample of children. Data were analysed using optimized voxel-based morphometry. Study-specific probability maps were created and four a priori regions of interest identified (orbitofrontal, anterior cingulate and anterior insular cortices and amygdala). Both grey matter volume and concentration were examined controlling for cognitive ability and hyperactivity-inattention symptoms. Boys with callous-unemotional conduct problems, as compared with typically developing boys, presented increased grey matter concentration in the medial orbitofrontal and anterior cingulate cortices, as well as increased grey matter volume and concentration in the temporal lobes bilaterally. These findings may indicate a delay in cortical maturation in several brain areas implicated in decision making, morality and empathy in boys with callous-unemotional conduct problems.