Twenty-four adolescents with familial ADHD and 10 control youths underwent high-resolution structural MRI, and frontal lobe gyri and caudate were compared in a study at Stanford University and other US centers. Youths with ADHD had larger right caudate and right inferior frontal lobe volumes than control subjects. An increase in left caudate volume in a subgroup of ADHD youths was correlated with decreasing functional activation in this region. The findings were thought to reflect neurodevelopmental changes specific to late adolescence in familial ADHD. [1]

COMMENT. Neuroanatomical abnormalities detected in patients with ADHD support the neurobiological basis for this symptom complex. The authors cite a meta-analysis of structural imaging research that indicates regions most frequently affected include total cerebral volume, caudate nucleus, splenium of the corpus callosum, cerebellum and frontal lobes. Differences in findings may be attributable to differences in age of subjects selected and the weight of hereditary compared to environmental causes of ADHD [2]. The selection of cases with familial ADHD by the Stanford group is a more homogeneous sample than some, emphasizing the neural correlates of inherited forms of the disorder. The possible influence of associated environmental factors is not excluded, however.