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Effects of stimulant medication, incentives, and event rate on reaction time variability in children with ADHD.

ABSTRACT: This study examined the effects of methylphenidate (MPH) on reaction time (RT) variability in children with attention deficit hyperactivity disorder (ADHD). Using a broad battery of computerized tasks, and both conventional and ex-Gaussian indicators of RT variability, in addition to within-task manipulations of incentive and event rate (ER), this study comprehensively examined the breadth, specificity, and possible moderators of effects of MPH on RT variability. A total of 93 children with ADHD completed a 4-week within-subject, randomized, double-blind, placebo-controlled crossover trial of MPH to identify an optimal dosage. Children were then randomly assigned to receive either their optimal MPH dose or placebo after which they completed five neuropsychological tasks, each allowing trial-by-trial assessment of RTs. Stimulant effects on RT variability were observed on both measures of the total RT distribution (ie, coefficient of variation) as well as on an ex-Gaussian measure examining the exponential portion of the RT distribution (ie, ?). There was minimal, if any, effect of MPH on performance accuracy or RT speed. Within-task incentive and ER manipulations did not appreciably affect stimulant effects across the tasks. The pattern of significant and pervasive effects of MPH on RT variability, and few effects of MPH on accuracy and RT speed suggest that MPH primarily affects RT variability. Given the magnitude and breadth of effects of MPH on RT variability as well as the apparent specificity of these effects of MPH on RT variability indicators, future research should focus on neurophysiological correlates of effects of MPH on RT variability in an effort to better define MPH pharmacodynamics.

SUBMITTER: Epstein JN

PROVIDER: S-EPMC3059336 | biostudies-literature | 2011 Apr

REPOSITORIES: biostudies-literature

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Effects of stimulant medication, incentives, and event rate on reaction time variability in children with ADHD.

Epstein Jeffery N JN Brinkman William B WB Froehlich Tanya T Langberg Joshua M JM Narad Megan E ME Antonini Tanya N TN Shiels Keri K Simon John O JO Altaye Mekibib M

Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology 20110119 5

This study examined the effects of methylphenidate (MPH) on reaction time (RT) variability in children with attention deficit hyperactivity disorder (ADHD). Using a broad battery of computerized tasks, and both conventional and ex-Gaussian indicators of RT variability, in addition to within-task manipulations of incentive and event rate (ER), this study comprehensively examined the breadth, specificity, and possible moderators of effects of MPH on RT variability. A total of 93 children with ADHD ...[more]

PMID: 21248722

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Project description:The objective of this study was to examine factors that are associated with aggression that is responsive versus refractory to individualized optimization of stimulant monotherapy among children with attention-deficit/hyperactivity disorder (ADHD).Children who were aged 6 to 13 years and had ADHD, either oppositional defiant disorder or conduct disorder, significant aggressive behavior, and a history of insufficient response to stimulants completed an open stimulant monotherapy optimization protocol. Stimulant titration with weekly assessments of behavior and tolerability identified an optimal regimen for each child. Families also received behavioral therapy. Parents completed the Retrospective-Modified Overt Aggression Scale (R-MOAS) at each visit. Children were classified as having stimulant-refractory aggression on the basis of R-MOAS ratings and clinician judgment. Differences that pertained to treatment, demographic, and psychopathology between groups with stimulant monotherapy-responsive and -refractory aggression were evaluated.Aggression among 32 (49.3%) of 65 children was reduced sufficiently after stimulant dosage adjustment and behavioral therapy to preclude adjunctive medication. Those who responded to stimulant monotherapy were more likely to benefit from the protocol's methylphenidate preparation (once-daily, triphasic release), showed a trend for lower average dosages, and received fewer behavioral therapy sessions than did children with stimulant-refractory aggression. Boys, especially those with higher ratings of baseline aggression and of depressive and manic symptoms, more often exhibited stimulant-refractory aggression.Among children whose aggressive behavior develops in the context of ADHD and of oppositional defiant disorder or conduct disorder, and who had insufficient response to previous stimulant treatment in routine clinical care, systematic, well-monitored titration of stimulant monotherapy often culminates in reduced aggression that averts the need for additional agents.

Dataset Information

Effects of stimulant medication, incentives, and event rate on reaction time variability in children with ADHD.

Publications

Effects of stimulant medication, incentives, and event rate on reaction time variability in children with ADHD.

Similar Datasets

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