Neurophysiological correlates of inhibitory control in adults with ADHD revealed by iterative independent component analysis

In this study, an improved method of iterative independent component analysis (iICA) on single-trial brain responses was employed to investigate neural mechanisms underlying inhibitory control deficits in adults with attention deficit / hyperactivity disorder (ADHD). Specially recorded data during a continuous performance task from 10 ADHD and 11 healthy control subjects were analyzed. Behavioral measures showed that the inconsistency in response speed were significantly greater in adults with ADHD compared to control subjects (p = 0.009). ERP data revealed ADHD group compared to healthy controls had a significant increase in N2 amplitudes while P3 amplitudes´ decreased particularly for shorter inter-stimulus intervals. Furthermore, N2 amplitude correlated with the number of ADHD symptoms. These results confirm the utility of the iICA method in discrimination between adults with ADHD and healthy comparison controls and strongly suggest that this method can be used for further evaluation of cognitive functioning.