Inhibitory performance, response speed, intraindividual variability, and response accuracy in ADHD.
OBJECTIVE
To determine the potential of inhibitory performance, response speed, and response accuracy and variability, measures central to the conceptualization of attention-deficit/hyperactivity disorder (ADHD), in distinguishing children with ADHD from healthy controls (HCs).


METHODS
The stop signal paradigm was administered to 38 children with ADHD and 31 NCs. The stop signal reaction time (SSRT), mean reaction time (MRT), intraindividual coefficient of variation (ICV), and number of errors were used to predict diagnostic status.


RESULTS
Univariate tests showed that the ADHD group performed worse than NCs on all of the dependent variables. Exploratory univariate analyses showed that oppositional defiant disorder comorbidity and ADHD type did not influence results except for the ICV, the effect for this variable (more variability in the ADHD group) being less pronounced for the Predominantly Inattentive type than for the Hyperactive-Impulsive and Combined types. A logistic regression model of the MRT, ICV, and number of errors combined showed best predictive performance, with the MRT contributing the most to group classification (56% of the variance). The final model (MRT, ICV, and number of errors) predicted 87% of the sample in the correct diagnostic category. Operating characteristics showed excellent sensitivity and specificity of 89.5% and 83.9%, respectively.


CONCLUSIONS
Our results contrast with theoretical accounts emphasizing inhibitory control as the pivotal measure characterizing cognitive performance in ADHD. Results are discussed in the context of a delay aversion perspective of ADHD.
de Zeeuw
Patrick
P
Department of Clinical Neuropsychology, VU University Amsterdam, the Netherlands. p.dezeeuw@umcutrecht.nl
Aarnoudse-Moens
Cornelieke
C
Bijlhout
Joyce
J
König
Claudia
C
Post Uiterweer
Annebeth
A
Papanikolau
Alky
A
Hoogenraad
Caecilia
C
Imandt
Lieke
L
de Been
Debbie
D
Sergeant
Joseph A
JA
Oosterlaan
Jaap
J
D000293:Adolescent; D001288:Attention; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis* / Q000523:psychology; D002648:Child; D003072:Cognition Disorders / Q000175:diagnosis* / Q000523:psychology; D005260:Female; D006801:Humans; D007206:Individuality; D007266:Inhibition, Psychological; D008297:Male; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D011594:Psychometrics / Q000706:statistics & numerical data; D011930:Reaction Time; D012016:Reference Values