title: Stimulant treatment reduces lapses in attention among children with ADHD: the effects of methylphenidate on intra-individual response time distributions.
abstract: Recent research has suggested that intra-individual variability in reaction time (RT) distributions of children with ADHD is characterized by a particularly large rightward skew that may reflect lapses in attention. The purpose of the study was to provide the first randomized, placebo-controlled test of the effects of the stimulant methylphenidate (MPH) on this tail and other RT distribution characteristics. Participants were 49 9- to 12-year-old children with ADHD. Children participated in a 3-day double-blind, placebo-controlled medication assessment during which they received long-acting MPH (Concerta), with the nearest equivalents of 0.3 and 0.6 mg/kg t.i.d. immediate-release MPH. Children completed a simple two-choice speeded discrimination task on and off of medication. Mode RT and deviation from the mode were used to examine the peak and skew, respectively, of RT distributions. MPH significantly reduced the peak and skew of RT distributions. Importantly, the two medication effects were uncorrelated suggesting that MPH works to improve both the speed and variability in responding. The improvement in variability with stimulant treatment is interpreted as a reduction in lapses in attention. This, in turn, may reflect stimulant enhancement of self-regulatory processes theorized to be at the core of ADHD.
authors.affiliation: Department of Psychology, University at Buffalo, SUNY, Park Hall, Box 604110, Buffalo, NY 14260-4110, USA.
authors.forename: Sarah V
authors.initials: SV
authors.lastname: Spencer
authors.forename: Larry W
authors.initials: LW
authors.lastname: Hawk
authors.forename: Jerry B
authors.initials: JB
authors.lastname: Richards
authors.forename: Keri
authors.initials: K
authors.lastname: Shiels
authors.forename: William E
authors.initials: WE
authors.lastname: Pelham
authors.forename: James G
authors.initials: JG
authors.lastname: Waxmonsky
mesh_terms: D001288:Attention / Q000187:drug effects*; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy*; D000697:Central Nervous System Stimulants / Q000627:therapeutic use*; D002648:Child; D004192:Discrimination, Psychological / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008774:Methylphenidate / Q000627:therapeutic use*; D009518:New York; D011930:Reaction Time / Q000187:drug effects*; D013647:Task Performance and Analysis
chemical_list: D000697:Central Nervous System Stimulants; D008774:Methylphenidate