Inhibitory deficits in attention-deficit/hyperactivity disorder are independent of basic processing efficiency and IQ.
BACKGROUND
A substantial proportion of children with attention-deficit/hyperactivity disorder (ADHD) show deficits on inhibitory control tests. However, questions remain about (i) the extent of these deficits across different inhibitory domains, (ii) their relationship to deficits in non-executive processes and (iii) whether they extend into adolescence.


METHODS
Seventy-seven children and adolescents with ADHD and 50 non-ADHD controls completed three inhibitory tasks, a simple two choice RT task (2CR) and an IQ assessment.


RESULTS
ADHD was moderately associated with deficits on all tasks (effect sizes d=0.5-0.9). Deficits were equally marked in childhood and adolescence. Inhibitory deficits were not associated with IQ and, although reduced substantially, remained significant after performance on a simple reaction time task was controlled for statistically.


CONCLUSIONS
In highlighting the significant, but limited, role of inhibitory deficits in ADHD, these results are consistent with recent accounts that emphasize the neuropsychological heterogeneity of this condition.
Bitsakou
P
P
Institute for Disorder on Impulse and Attention, University of Southampton, Southampton, UK.
Psychogiou
L
L
Thompson
M
M
Sonuga-Barke
E J S
EJ
D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000150:complications*; D002648:Child; D002755:Choice Behavior / Q000502:physiology; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D007360:Intelligence / Q000502:physiology*; D007859:Learning Disabilities / Q000209:etiology*; D008297:Male; D015999:Multivariate Analysis; D009483:Neuropsychological Tests; D011930:Reaction Time / Q000502:physiology; D014888:Wechsler Scales