In a study at Massachusetts General Hospital, Magnetic Resonance Imaging (MRI) brain scans revealed that boys meeting criteria for ADHD differed from non-ADHD control boys with respect to the following brain characteristics: Reversed asymmetry of the head of the caudate; smaller volume of the caudate head; and smaller volume of the white matter of the right frontal lobe (Semrud-Clikeman et al., 2000).

The ADHD boys also had significantly higher CBCL Externalizing and Internalizing scores as well as significantly poorer scores on several neuropsychological measures. In addition, CBCL Externalizing scores were significantly higher for boys having the smallest caudate heads, whereas CBCL Internalizing scores were significantly associated with caudate asymmetry. The authors concluded that “the finding of a relationship between the inability to inhibit responding and a compromised caudate supports the emerging evidence of disruption in the frontostriatal circuits in ADHD.”

Reference: Semrud-Clikeman, M., Steingard, R.J., Filipek, P., Biederman, J., Bekken, K., & Renshaw, P.F. (2000). Using MRI to examine brain-behavior relationships in males with Attention Deficit Disorder with Hyperactivity. Journal of the American Academy of Child & Adolescent Psychiatry, 39, 477-484.