A NEUROPSYCHOLOGICAL EXAMINATION OF THE UNDERLYING DEFICIT IN ATTENTION-DEFICIT HYPERACTIVITY DISORDER - FRONTAL-LOBE VERSUS RIGHT PARIETALLOBE THEORIES

A neuropsychological approach was used to examine the frontal lobe and right parietal lobe theories of attention deficit hyperactivity disor der (ADHD). Considerable attempts were made to select as pure a group of ADHD boys as possible. The performance of 10-14-year-old ADHD boys (n = 22), both on and off stimulant medication, was compared with the performance of non-ADHD control boys (n = 22) on tasks purported to as sess frontal lobe functioning (Stopping Task, Antisaccade Task, Tower of Hanoi) and right parietal lobe functioning (Visual-Spatial Cuing Ta sk, Turning Task, Spatial Relations). Three important findings emerged : (a) unmedicated ADHD boys exhibited performance deficits on tasks in both frontal and parietal domains compared with control boys, (b) unm edicated ADHD boys appeared to be more severely impaired on the fronta l tasks than on the parietal tasks, and (c) medicated ADHD boys perfor med better in both task domains compared with unmedicated ADHD boys. S everal alternative interpretations of the results are discussed.