RIGHT-HEMISPHERE DYSFUNCTION AND METHYLPHENIDATE EFFECTS IN CHILDREN WITH ATTENTION-DEFICIT HYPERACTIVITY DISORDER

The purposes of this study were to investigate the previously reported right hemisphere dysfunction in children with attention-deficit/hyper activity disorder (ADHD) and to test for stimulant medication treatmen t effects. Seventeen children with ADHD were assessed on a letter canc ellation task on placebo and on methylphenidate. On placebo, ADHD chil dren detected fewer targets on the left side of the page than on the r ight side of the page, thus demonstrating evidence of partial left vis ual field neglect and, by implication, right hemisphere dysfunction. T he ADHD children with comorbid learning disabilities appeared to large ly account for this result. On medication, there was no longer evidenc e of the partial left visual field neglect or right hemisphere dysfunc tion. Thus, it appears that ADHD, particularly with comorbid learning disabilities, may involve right hemisphere dysfunction which is partia lly corrected with methylphenidate.