Functional brain electrical activity mapping in boys with attention-deficit/hyperactivity disorder

Background: Symptoms of attention-deficit/hyper-activity disorder (ADHD) ha ve been associated with frontal lobe deficits. We used a novel brain electr ical imaging method to investigate rapid and continuous changes in brain ac tivity during the continuous performance task (CPT) in normal boys and in b oys with ADHD. The amplitude and latency topography of the steady-state vis ually evoked potential (SSVEP) were examined while subjects performed the " X" version of the CPT (CPT-X; the reference task) and the "A-X" version of the CPT (CPT-AX). Methods: Seventeen boys meeting DSM-III-R criteria for ADHD and 17 age-matc hed controls participated in the study. Brain electrical activity was recor ded from 64 scalp sites. During the reference task, subjects pressed a micr oswitch on the unpredictable appearance of the letter X. During the CPT-AX, subjects were required to press the microswitch on the appearance of the l etter X only if an A had preceded it. Results: In the interval between the appearances of the A and the X of the correct trials of the CPT-AX, control boys showed transient reductions in S SVEP latency at right prefrontal sites. By contrast, boys with ADHD showed no change or an increase in prefrontal SSVEP latency at right prefrontal si tes. Conclusion: Our results suggest increased speed of prefrontal neural proces sing in children without ADHD following a priming stimulus, and a deficit i n such processes in children with ADHD.