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Effects of methylphenidate on working memory components: influence of measurement

Authors

  • Anne-Claude Bedard,

    1. Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
    2. Neuroscience and Mental Health Research Program, The Hospital for Sick Children, Toronto, Canada
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  • Umesh Jain,

    1. Centre for Addiction and Mental Health, Toronto, Canada
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  • Sheilah Hogg Johnson,

    1. Institute for Work and Health, University of Toronto, Toronto, Canada
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  • Rosemary Tannock

    1. Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
    2. Neuroscience and Mental Health Research Program, The Hospital for Sick Children, Toronto, Canada
    3. Ontario Institute for Special Education, University of Toronto
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  • Conflict of interest statement: Dr Jain sits on the Advisory Boards of Biovail, Wyeth, Purdue, Eli Lilly, Shire, and Janssen-Ortho, has sponsorships from Wyeth, Purdue, Eli Lilly, Shire, Janssen-Ortho, and Novartis, and does research for Purdue, Eli Lilly, and Janssen-Ortho. Neither he nor his family has financial interests in these companies. Dr Tannock receives research funds from Eli Lilly, Shire, and Novartis, sits on the Advisory Boards of Eli Lilly and Pfizer, acts as a consultant to Eli Lilly, is a member of the Speaker's Bureau of Eli Lilly and McNeil, and receives honoraria from Eli Lilly, Shire, Janssen-Ortho, McNeil, and Pfizer.

Rosemary Tannock, Neuroscience and Mental Health Research Program, The Hospital for Sick Children, 555 University Ave., Toronto, Canada M5G1X8; Tel: 416-813-7048; Fax: 416-813-6565; Email: rosemary.tannock@utoronto.ca

Abstract

Background:  To investigate the effects of methylphenidate (MPH) on components of working memory (WM) in attention-deficit hyperactivity disorder (ADHD) and determine the responsiveness of WM measures to MPH.

Methods:  Participants were a clinical sample of 50 children and adolescents with ADHD, aged 6 to 16 years old, who participated in an acute randomized, double-blind, placebo-controlled, crossover trial with single challenges of three MPH doses. Four components of WM were investigated, which varied in processing demands (storage versus manipulation of information) and modality (auditory-verbal; visual-spatial), each of which was indexed by a minimum of two separate measures.

Results:  MPH improved the ability to store visual-spatial information irrespective of instrument used, but had no effects on the storage of auditory-verbal information. By contrast, MPH enhanced the ability to manipulate both auditory-verbal and visual-spatial information, although effects were instrument specific in both cases.

Conclusions:  MPH effects on WM are selective: they vary as a function of WM component and measurement.

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