Behavioral performance predicts grey matter reductions in the right inferior frontal gyrus in young adults with combined type ADHD.

Optimized voxel-based morphometry (VBM) was used in the present study to investigate morphometric differences between young adults with combined type Attention Deficit/Hyperactivity Disorder (ADHD) and a well-matched control group. Investigations examined differences on a between-group whole brain level, as well as how individual differences in behavioral performance predicted grey matter differences. Although a whole brain analysis revealed no significant differences between ADHD and control individuals, ADHD but not control individuals exhibited reduced grey matter volume in the right inferior frontal gyrus (rIFG), predicted by poorer behavioral performance on all three measures. A subsequent region-of-interest approach revealed lower grey matter volume in the rIFG in ADHD compared to control individuals. These results suggest that young adults with ADHD show morphometric differences in inferior prefrontal regions, as compared to controls. These morphometric differences are related to disruptions in performance on behavioral tasks that frequently have been reported to be affected in individuals with ADHD.