title: Methylphenidate, modafinil, and caffeine for cognitive enhancement in chess: A double-blind, randomised controlled trial.
abstract: Stimulants and caffeine have been proposed for cognitive enhancement by healthy subjects. This study investigated whether performance in chess - a competitive mind game requiring highly complex cognitive skills - can be enhanced by methylphenidate, modafinil or caffeine. In a phase IV, randomized, double-blind, placebo-controlled trial, 39 male chess players received 2×200mg modafinil, 2×20mg methylphenidate, and 2×200mg caffeine or placebo in a 4×4 crossover design. They played twenty 15-minute games during two sessions against a chess program (Fritz 12; adapted to players' strength) and completed several neuropsychological tests. Marked substance effects were observed since all three substances significantly increased average reflection time per game compared to placebo resulting in a significantly increased number of games lost on time with all three treatments. Treatment effects on chess performance were not seen if all games (n=3059) were analysed. Only when controlling for game duration as well as when excluding those games lost on time, both modafinil and methylphenidate enhanced chess performance as demonstrated by significantly higher scores in the remaining 2876 games compared to placebo. In conjunction with results from neuropsychological testing we conclude that modifying effects of stimulants on complex cognitive tasks may in particular result from more reflective decision making processes. When not under time pressure, such effects may result in enhanced performance. Yet, under time constraints more reflective decision making may not improve or even have detrimental effects on complex task performance.
authors.affiliation: Department of Psychiatry and Psychotherapy, University Medical Center Mainz, Untere Zahlbacher Str. 8, D-55131 Mainz, Germany; University of Neubrandenburg, University of Applied Sciences, Department of Social Work and Education, Brodaer Str. 2, 17033 Neubrandenburg, Germany. Electronic address: franke@hs-nb.de.
authors.forename: Andreas G
authors.initials: AG
authors.lastname: Franke
authors.affiliation: SOFI, Stockholm University, Swedish Institute for Social Research, Stockholm University, SE - 10691 Stockholm, Sweden. Electronic address: patrik.gransmark@sofi.su.se.
authors.forename: Patrik
authors.initials: P
authors.lastname: Gränsmark
authors.affiliation: Department of Psychiatry and Psychotherapy, University Medical Center Mainz, Untere Zahlbacher Str. 8, D-55131 Mainz, Germany. Electronic address: agricola@students.uni-mainz.de.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Agricola
authors.affiliation: Department of Psychiatry and Psychotherapy, University Medical Center Mainz, Untere Zahlbacher Str. 8, D-55131 Mainz, Germany. Electronic address: schuehle@students.uni-mainz.de.
authors.forename: Kai
authors.initials: K
authors.lastname: Schühle
authors.affiliation: Department of Psychiatry and Psychotherapy, University Medical Center Mainz, Untere Zahlbacher Str. 8, D-55131 Mainz, Germany; Department of Psychology, Section for Clinical Psychology and Psychotherapy, University of Mainz, Wallstr. 3, 55122 Mainz, Germany. Electronic address: thilo.rommel@googlemail.com.
authors.forename: Thilo
authors.initials: T
authors.lastname: Rommel
authors.affiliation: Department of Psychiatry and Psychotherapy, University Medical Center Mainz, Untere Zahlbacher Str. 8, D-55131 Mainz, Germany. Electronic address: alexandra.sebastian@unimedizin-mainz.de.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Sebastian
authors.affiliation: Department of Psychiatry and Psychotherapy, University Medical Center Mainz, Untere Zahlbacher Str. 8, D-55131 Mainz, Germany; Internistisch-onkologische Gemeinschaftspraxis, Marktplatz 11, 63065 Offenbach am Main, Germany. Electronic address: Harald.Ballo@t-online.de.
authors.forename: Harald E
authors.initials: HE
authors.lastname: Balló
authors.affiliation: Interdisciplinary Center for Clinical Trials (IZKS), University Medical Center Mainz, Langenbeckstr. 1, 55131 Mainz, Germany. Electronic address: gorbulev@izks-mainz.de.
authors.forename: Stanislav
authors.initials: S
authors.lastname: Gorbulev
authors.affiliation: SOFI, Stockholm University, Swedish Institute for Social Research, Stockholm University, SE - 10691 Stockholm, Sweden. Electronic address: christer.gerdes@sofi.su.se.
authors.forename: Christer
authors.initials: C
authors.lastname: Gerdes
authors.affiliation: University of Kassel, Department of Economics, Nora-Platiel-Str. 4, 34127 Kassel, Germany. Electronic address: frank@uni-kassel.de.
authors.forename: Björn
authors.initials: B
authors.lastname: Frank
authors.affiliation: Interdisciplinary Center for Clinical Trials (IZKS), University Medical Center Mainz, Langenbeckstr. 1, 55131 Mainz, Germany. Electronic address: ruckes@izks-mainz.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Ruckes
authors.affiliation: Department of Psychiatry and Psychotherapy, University Medical Center Mainz, Untere Zahlbacher Str. 8, D-55131 Mainz, Germany. Electronic address: oliver.tuescher@unimedizin-mainz.de.
authors.forename: Oliver
authors.initials: O
authors.lastname: Tüscher
authors.affiliation: Department of Psychiatry and Psychotherapy, University Medical Center Mainz, Untere Zahlbacher Str. 8, D-55131 Mainz, Germany. Electronic address: klaus.lieb@unimedizin-mainz.de.
authors.forename: Klaus
authors.initials: K
authors.lastname: Lieb
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001559:Benzhydryl Compounds; D002110:Caffeine / Q000494:pharmacology; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003071:Cognition / Q000187:drug effects*; D003430:Cross-Sectional Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008774:Methylphenidate / Q000494:pharmacology; D008875:Middle Aged; D000077408:Modafinil; D009483:Neuropsychological Tests; D012189:Retrospective Studies; D064690:Wakefulness-Promoting Agents / Q000494:pharmacology*
chemical_list: D001559:Benzhydryl Compounds; D000697:Central Nervous System Stimulants; D064690:Wakefulness-Promoting Agents; D008774:Methylphenidate; D002110:Caffeine; D000077408:Modafinil
keywords: Caffeine; Chess; Cognitive enhancement; Methylphenidate; Modafinil; Stimulants