Caudate and anterior cingulate cortex (ACC) volumes, measured by structural MRI, were compared in children with ADHD, previously treated and untreated, and controls, in a study at the University of Texas, San Antonio and Austin; and researchers from the UK and Canada. Caudates were smaller bilaterally in both ADHD groups compared to controls. The right ACC was significantly smaller in the ADHD-treatment naïve (-TN) group compared to the ADHD-treated and control groups. In contrast, the left ACC showed no significant difference in size among the 3 groups; however, it was smaller in the ADHD-TN group compared to controls (p=0.07). Smaller left caudate volume was associated with more restlessness/impulsivity on the parent Conners scale for ADHD groups. Smaller caudates bilaterally were found in children with ADHD, and smaller caudates were associated with inattention on the Behavior Assessment Parent scale. Volume of ACC was not related to attention scores. 
COMMENT. Caudate and anterior cingulate volumes are different in children with ADHD-combined type compared to controls. Parent-rated behavioral measures of attention and response inhibition are correlated with caudate, but not cingulate, size in ADHD patients. Restless/impulsive behavior is correlated with a smaller left caudate, whereas inattentiveness is associated with bilateral caudate volume reduction. A small right cingulate is a feature of untreated ADHD children compared to those treated and normal controls, whereas the left cingulate shows no significant difference in ADHD patients, treated or untreated, and controls. Long-term stimulant therapy for ADHD may be expected to normalize ACC volume.