Neuronal network models of ADHD - lateralization with respect to interhemispheric connectivity reconsidered

Background. Recent research on structural and functional anatomy related to ADHD has concentrated on fronto-striatocerebellar circuits. These findings and resultant neurobiological models of ADHD may explain some of the disturbances. On the other hand, there is some evidence that the restricted look at anteriorposterior anomalies might neglect the important additional information of lateralization problems related to hemispheric connectivity. Objective. Hence, the role of lateralization in the pathophysiology of ADHD should be reconsidered. Method. After a short review of imaging studies in ADHD the special role of the corpus callosum (including the influence of its anomalies on general brain development, lateralization and functioning) is outlined and the first case of total agenesis of corpus callosum in a child with ADHD is presented and discussed within this context. Conclusions. In view of the remaining inconsistencies concerning structural and functional brain anomalies in ADHD, attention should be paid not only to anterior- posterior but also to leftright aspects of functional and structural brain anomalies. This should include disturbances probably related to anomalies of the corpus callosum, especially in regard to co-existing problems like dyslexia and developmental coordination disorder.