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).
Results:
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.
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