Right fronto-parietal dysfunction in children with ADHD and developmental dyslexia as determined by line bisection judgements.

Visual line bisection is a reliable and valid laterality task that is typically used with patients with acquired brain damage to assess right hemisphere functioning. Neurologically normal individuals tend to bisect lines to the left of the objective midline whereas those with right parietal damage bisect lines to the right. In this study children with ADHD were matched with children with developmental dyslexia on IQ and gender to test the hypothesis that right hemisphere neurological abnormalities underlie the behavioural deficits observed in these two disorders. Line bisection performance was compared between groups as a function of response hand, scanning direction and line position. In contrast to results typically found with neurologically normal children, a rightward bias was found for both clinical groups, but to different degrees depending on which hand was used to bisect lines. These findings suggest pathology of the corpus callosum and/or the right fronto-parietal cortex.