Right Hemisphere Dysfunction and Methylphenidate Effects in Children with Attention-Deficit/ Hyperactivity Disorder

Abstract

The purposes of this study were to investigate the previously reported right hemisphere dysfunction in children with attention-deficit/hyperactivity disorder (ADHD) and to test for stimulant medication treatment effects. Seventeen children with ADHD were assessed on a letter cancellation task on placebo and on methylphenidate. On placebo, ADHD children detected fewer targets on the left side of the page than on the right side of the page, thus demonstrating evidence of partial left visual field neglect and, by implication, right hemisphere dysfunction. The ADHD children with comorbid learning disabilities appeared to largely account for this result. On medication, there was no longer evidence of the partial left visual field neglect or right hemisphere dysfunction. Thus, it appears that ADHD, particularly with comorbid learning disabilities, may involve right hemisphere dysfunction which is partially corrected with methylphenidate.