title: The effect of methylphenidate on response inhibition and the event-related potential of children with attention deficit/hyperactivity disorder.
abstract: Children with Attention Deficit/Hyperactivity Disorder (AD/HD) appear to be deficient in inhibitory processes, as reflected in behavioural and electrophysiological measures. This study examined the effect of methylphenidate (MPH) on response inhibition in children with AD/HD. Event-related potentials (ERPs) and skin conductance level (SCL) were recorded from 18 boys with AD/HD and 18 controls while they performed a cued Go/Nogo task with 70% Go probability. All participants performed the task twice, with an hour interval between test sessions. At the beginning of this interval children with AD/HD took their normal morning dose of MPH. The AD/HD group showed lower SCL than controls pre-medication, a difference not found subsequent to the administration of MPH. While the AD/HD group made more overall errors (omission+commission) pre-medication, and continued to make more omission errors than controls post-medication, the groups became comparable on the number of commission errors, suggesting MPH ameliorates deficits in response inhibition. Children with AD/HD displayed enhanced N1 and P2 amplitudes, and reduced N2 amplitudes relative to controls. These differences were not significant post-medication, at least partly attributable to the action of MPH. This study is unusual in the concurrent examination of electrodermal and electrophysiological measures of medication effects in children with AD/HD, with the retesting of both the AD/HD and control groups allowing a more valid estimate of the effects of medication, rather than assuming that retesting does not have a substantial impact.
authors.affiliation: Department of Psychology and Brain & Behaviour Research Institute, University of Wollongong, Wollongong 2522, Australia. j.l.kenemans@fss.uu.nl
authors.forename: Samantha J
authors.initials: SJ
authors.lastname: Broyd
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Johnstone
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Barry
authors.forename: Adam R
authors.initials: AR
authors.lastname: Clarke
authors.forename: Rory
authors.initials: R
authors.lastname: McCarthy
authors.forename: Mark
authors.initials: M
authors.lastname: Selikowitz
authors.forename: Carlie A
authors.initials: CA
authors.lastname: Lawrence
mesh_terms: D000293:Adolescent; D000367:Age Factors; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy* / Q000503:physiopathology; D000697:Central Nervous System Stimulants / Q000008:administration & dosage*; D002648:Child; D005072:Evoked Potentials, Auditory / Q000187:drug effects*; D005712:Galvanic Skin Response / Q000187:drug effects; D006801:Humans; D008297:Male; D008774:Methylphenidate / Q000008:administration & dosage*; D009433:Neural Inhibition / Q000187:drug effects*; D011930:Reaction Time / Q000187:drug effects
chemical_list: D000697:Central Nervous System Stimulants; D008774:Methylphenidate