Altered effect of preceding response execution on inhibitory processing in children with AD/HD: An ERP study.

The electrophysiological findings in children with attention-deficit/hyperactivity disorder (AD/HD) have been repeatedly examined through a series of event-related potential (ERP) studies involving tasks that require inhibitory processing. Previous behavioral studies showed that the difficulty in response withholding for AD/HD children is enhanced by the preceding Go-trial. However, studies on the effects of the preceding response execution on the inhibitory ERP components in children with AD/HD have been scarce. Twelve children with AD/HD (6 with predominantly inattentive type, 6 with combined type) and 12 exhibiting typical development took a visual continuous performance test (CPT) involving Go/NoGo methodology. The effect of the preceding trial was analyzed by comparing ERP components and performance data between switch and repeat trials. Within-group comparison revealed that a significantly larger amplitude of NoGo-N200 for NoGo-switch (Go/NoGo) versus NoGo-repeat (NoGo/NoGo) was observed across sagittal regions in the control group but not in the AD/HD one. Between-group comparison revealed that the amplitude of NoGo-N200 for NoGo-switch across sagittal regions was significantly smaller in the AD/HD group than in the control one. The effect of the preceding trial on NoGo-N200 did not differ between two AD/HD subtypes. Moreover, the amplitudes and latencies of the ERP components elicited by Go-trials were not influenced by the type of preceding trial. These results suggested that the effect of preceding response execution on NoGo-N200 is greatly affected in children with AD/HD.