Methylphenidate improves Stroop naming speed, but not response interference, in children with attention deficit hyperactivity disorder.
OBJECTIVE
The goal of this study was to investigate the effect of methylphenidate (MPH) on response interference, as measured by the Stoop Color and Word Test, in children with attention deficit hyperactivity disorder (ADHD). Response interference is a core component of response inhibition that has been shown to be impaired in children with ADHD.


METHODS
A clinic-referred sample of school-aged children with a confirmed Diagnostic and Statistical Manual of Mental Disorders (4th ed.) diagnosis of ADHD and good reading skills (n = 31) completed the Stroop Color and Word Test in an acute, randomized, placebo-controlled, crossover trial with three single fixed doses of MPH.


RESULTS
MPH did not improve response interference on the Stroop Color and Word Test but did significantly improve color naming and word naming abilities.


CONCLUSIONS
Response interference, as measured by the Stroop Color and Word Test, is not improved by MPH in children with ADHD. In addition, findings demonstrate strongly positive MPH effects on the highly effortful process of color naming, which has previously been demonstrated as impaired in children with ADHD. MPH was also shown to have a positive but smaller effect on word naming speed.
Bedard
Anne-Claude
AC
Institute of Medical Science, The University of Toronto and Brain and Behaviour Research Unit, The Hospital for Sick Children, Toronto, Ontario, Canada. tannock@sickkids.on.ca
Ickowicz
Abel
A
Tannock
Rosemary
R
D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis / Q000188:drug therapy* / Q000523:psychology*; D000697:Central Nervous System Stimulants / Q000627:therapeutic use*; D002648:Child; D003118:Color Perception / Q000187:drug effects; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008774:Methylphenidate / Q000627:therapeutic use*; D009483:Neuropsychological Tests; D011214:Practice, Psychological; D011569:Psychiatric Status Rating Scales; D011597:Psychomotor Performance / Q000502:physiology; D011932:Reading; D014888:Wechsler Scales
D000697:Central Nervous System Stimulants; D008774:Methylphenidate