MRI measurements of the head of the caudate nucleus correlated with neuropsychological deficits and behavioral problems in 11 adolescents with ADHD in a study at the University of Barcelona, Spain. The ADHD group had a larger right caudate nucleus and a trend toward a larger left caudate than a control group of 19 healthy subjects. Larger caudate nuclei in controls were associated with poorer performance on tests of attention and higher ratings on the Conners Teachers Rating Scale. A L>R pattern of caudate asymmetry was present in the control group and a reverse pattern (R>L) for the ADHD subjects. A bilateral dysfunction is suggested for ADHD, more pronounced on the right side. 
COMMENT. This study provides further evidence of a neuropathological or developmental structural defect underlying behavioral and cognitive abnormalities in adolescents with ADHD. Caudate volume normally decreases with increasing age, but in children with ADHD this maturational process is delayed or absent. These findings support the hypothesis of a frontal-striatal dysfunction in the mechanism of ADHD. (Progress in Ped Neurology III, 1997;pl98, 212). Structural cerebral anomalies in ADHD reported previously have involved the corpus callosum (Semrud-Clikeman M et al. 1994), caudate nucleus and other regions (Castellanos FX et al. 1996), and the left temporal lobe (Millichap JG, 1997).