Wild-Wall, N., Oades, R. D., Schmidt-Wessels, M., Christiansen, H., & Falkenstein, M. Neural correlates of executive functions in Attention-Deficit/ Hyperactivity Disorder (ADHD).
2008: Human Cognitive Neurophysiology, 2, 3.

Introduction: To assess changes of different executive functions & their neural correlates in children with ADHD & their unaffected siblings with respect to healthy control children.

Methods: Specifically, we studied the processing of irrelevant stimuli, the control over inappropriate responses, and the detection of errors using a modified flanker task. Event-related potentials (ERPs) were used to directly measure these processes in a group of 15 children with ADHD (DSM-IV diagnosis from the PACS interview), 12 of their siblings and 12 independent typically developing children (mean age range 13-14 years).

1 - While the behavioral data showed no major significant group differences on separate comparisons of the three groups, the ERPs did.

2 - The post-stimulus ERPs mainly showed an attenuation of flanker processing (P1 amplitude at T5 and T6) - and later N2 and P3a components in the ADHD group.

3 - The post-response ERPs showed a general enhancement of the post-response negativity in the siblings. In particular there was no significant attenuation of error processing, as reflected in Ne/ERN & Pe, on the ADHD vs. control group comparisons.....[ but comparing the ADHD group vs. Siblings + Controls showed that the Ne was reduced (FCz) & the Pe was increased (Cz at c. 200 ms)].

4 - Finally, preparatory processes (CNV like negativity) were attenuated in siblings and more so in the patients.

Discussion: The pattern of results reveals a) specific changes of various cognitive control processes in ADHD which are not reflected in overt behaviour. b) The larger post-response potentials in the unaffected siblings may reflect compensatory enhancement of response monitoring. c) The study shows that ERPs have an additive value for assessing subtle cognitive changes in ADHD.

Support in part from the NIH