Event-Related Potential of Early Inhibition Process and Neuropsychological Functions as index to Explore Subgroups of Children with Attention Deficit Hyperactivity Disorder

Abstract

SUMMARY Behavioral disinhibition is a critical problem in ADHD children and it may cause a wide range of adverse outcomes in developmental processes From the perspective of neuropsychology executive attention function(EAF) is often used to investigate the behavioral disinhibition of ADHD Seldom of researches had examined the relationship of neurophysiological indicators and neuropsychological functions The aim of this study is to investigate the relationship between neurophysiological indicators and neuropsychological functions in order to screen attention problems in ADHD Participants were 44 seven to sixteen-year-old ADHD children and 44 children with comparable age gender home environment IQ and social economic status The EEG was carried out during a 4-min simple reaction time (SRT) task as standard procedure The stimulus-locked ERP of N2 and P3 was defined as conflict monitoring and response inhibition respectively The study revealed that (1) ADHD-IE had significant poor EAFs than did the ADHD-Without IE and control group (2) The ADHD group had significant less N2/P3 than did the control group where subjects successfully inhibited a response (3) the ADHD-less N2/P3 group had significant poor objective EAFs on neuropsychological assessment The result indicated that ADHD children had more IEs and less N2/P3 in SRT task which revealed the inhibition and monitoring processes deficit in early inhibition process In addition ADHD-less N2 children might be confirmed a meaningful subgroup that needs close follow-up treatments different from standard or both Key words: attention deficit hyperactivity disorder (ADHD) executive attention function(EAF) impulsive error neurophysiological indicator N2/P3 INTRODUCTION Endophenotypes for psychopathology have been conceived as unobserved but measurable manifestations of phenomena that connect genetic liability to clinical disorders (Miller & Rockstroh 2013) Kropotov(2009) also suggested more accurate psychiatric diagnosis can be made using knowledge about brain systems and brain operations Franke Neale & Faraone (2009) reviewed genome-wide association studies suggested 3 level of concepts of endophenotype in ADHD Functions of brain unit are involved in disease related endophenotypes as level1 which are seen as neuropsychological functions Level 2 are brain structure or functional neuroimages From the perspective of neuropsychology several studies which used executive attention function(EAF) as endophenotype often investigate the behavioral disinhibition of ADHD Among them response inhibition and conflict monitoring are the major neuropsychological functions that are often explored in ADHD Several researches claimed ADHD children have both neuropsychological/neurobehavioral and neuroimagical function impairments But seldom of them had examined the relationship of neurophysiological indicators and neuropsychological functions The aim of this study is to investigate the relationship between neurophysiological indicators and neuropsychological functions in order to screen attention problems in ADHD MATERIALS AND METHODS Participants were 44 seven to sixteen-year-old ADHD children and 44 children with comparable age gender home environment IQ and social economic status The EEG was carried out during a 4-min simple reaction time (SRT) task as standard procedure The stimulus-locked ERP of N2 and P3 was defined as conflict monitoring and response inhibition respectively EAFs were assessed by Comprehensive Nonverbal Attention Test Battery (CNAT) as objective indices and behavioral questionnaires were used as subjective indices ADHD children are regrouped into ADHD-IE and ADHD-Without IE In addition the ADHD-IE group is also regrouped into ADHD-FI and ADHD-SI according to the reaction time of the impulsive error The amplitude of N2/P3 in the control group with IEs was used as the proper criterion for regrouping the ADHD children into two groups: ADHD children with enough N2(ADHD-enough N2) and those with less N2(ADHD-less-N2) Tower of London (ToL) and Wisconsin Card Sorting Test (WCST)were also administered in ADHD groups in order to examine the relationship of neurophysiological indicators and neuropsychological functions within ADHD groups RESULTS AND DISCUSSION (1) Seventy-five percent of ADHD children made IEs in SRT was significantly more than in the control group (48%) ADHD-IE had significant poor EAFs than did the ADHD-Without IE and control group (2) The ADHD group had significant less N2/P3 than did the control group where subjects successfully inhibited a response at frontal and central sites (3) Both ADHD-less N2/P3 and ADHD-enough N2/P3 groups had poorer subjective EAFs on questionnaires however the ADHD-less N2/P3 group had significant poor objective EAFs on neuropsychological assessment CONCLUSION ADHD children had more IEs and less N2/P3 in SRT task which revealed the inhibition and monitoring processes deficit in early inhibition process In addition IE and N2/P3 indicators of early inhibition process in ADHD children might help to differentiate subtypes of ADHD with different neuropsychological abilities and the possibility that ADHD-less N2 children might be confirmed a meaningful subgroup that needs close follow-up treatments different from standard or both We have developed neurophysiological and neuropsychological indicators only using a 4-minutes SRT during simultaneously EEG recording which can be used to screen EAF deficits N2/P3 of IE in SRT at pre-test and post-test point or during intervention also could be feedback signals as traing effects or targets Future studies should construct norms and validity of these indicators which can enhance clinical efficacy

Date of Award	2019
Original language	English
Supervisor	Nai-Wen Guo (Supervisor)