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.
SOFI, Stockholm University, Swedish Institute for Social Research, Stockholm University, SE - 10691 Stockholm, Sweden.
Eur Neuropsychopharmacol. 2017 Mar;27(3):248-260. doi: 10.1016/j.euroneuro.2017.01.006. Epub 2017 Jan 22.
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.
兴奋剂和咖啡因已被提议用于健康受试者的认知增强。本研究调查了哌甲酯、莫达非尼或咖啡因是否可以提高象棋（一种需要高度复杂认知技能的竞技思维游戏）的表现。在一项四期、随机、双盲、安慰剂对照试验中，39 名男性国际象棋选手以 4×4 交叉设计接受了 2×200mg 莫达非尼、2×20mg 哌甲酯和 2×200mg 咖啡因或安慰剂的治疗。他们在两个时段内与一个国际象棋程序（Fritz 12；适应选手的实力）进行了二十场 15 分钟的比赛，并完成了几项神经心理学测试。由于所有三种物质都显著增加了每场比赛的平均反射时间，导致所有三种治疗方法的超时比赛数量显著增加，因此观察到明显的物质效应。如果分析所有比赛（n=3059），则不会看到对比赛表现的治疗效果。只有在控制比赛持续时间的情况下，以及在排除超时输掉的比赛的情况下，莫达非尼和哌甲酯都能增强国际象棋表现，因为与安慰剂相比，在剩余的 2876 场比赛中，得分显著更高。结合神经心理学测试的结果，我们得出结论，兴奋剂对复杂认知任务的修饰作用可能特别源于更具反思性的决策过程。在没有时间压力的情况下，这种效果可能会导致表现提高。然而，在时间限制下，更具反思性的决策可能不会改善或甚至对复杂任务表现产生不利影响。
