Inhibition control and error processing in children with attention deficit/hyperactivity disorder: An event-related potentials study

We studied inhibitory control and error processing in a task requiring inhibition of a motor response. Behavioral and ERP indices were recorded in fourteen ADHD and fourteen healthy children aged between 6 and 10 years during the Stop signal task (SST). The ADHD group made more variable in RT and showed less accuracy, more omissions and choice errors. Also, the ADHD group had a tendency toward a lower probability of inhibition and a longer Stop signal reaction time. The ADHD group also displayed a flatter response inhibition slope compared to the control group. Smaller P1 in ADHD group reflected that the ADHD group has less efficient attention than the control group. Furthermore, the ADHD group showed normal ERN, reduced Pe (retrieved from response-locked epochs), and reduced LPW (retrieved from Stop signal-locked epochs), suggesting that they might be normal in early error monitoring process related to error detection, but show abnormal in later error monitoring process associated with a conscious evaluation of the error. Behavioral and ERP data of the present study show deficient selective attention, inhibitory control, and error processing in children of ADHD.

Research Highlights
► Impaired inhibitory control was shown in ADHD group during the Stop signal task.
► Smaller P1 in the ADHD group reflected less efficient attention in children with ADHD.
► ADHD group showed normal ERN, suggesting they seemed normal in error detection.
► Reduced Pe indicated ADHD might be abnormal during conscious evaluation of the error.
► Results implied multifaceted deficits of cognitive control in children with ADHD.