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.
Subject(s)
Central Nervous System Stimulants/pharmacology , Cognition/drug effects , Wakefulness-Promoting Agents/pharmacology , Adult , Analysis of Variance , Benzhydryl Compounds , Caffeine/pharmacology , Cross-Sectional Studies , Double-Blind Method , Female , Humans , Male , Methylphenidate/pharmacology , Middle Aged , Modafinil , Neuropsychological Tests , Retrospective StudiesABSTRACT
Affective reactions to health-related information play a central role in health anxiety. Therefore, using ambulatory assessment, we analysed the time course of negative affect in a control group (CG, n = 60) which only rated their negative affect and an experimental group (EG, n = 97) which also rated the presence of somatic symptoms (e.g., back pain). By means of mixed regression models, we observed a decline of negative affect following the symptom self-ratings in the EG and a stable affect in the CG. The decline of negative affect was not moderated by the degree of health anxiety. Our findings might indicate that evaluating one's health status leads to a general reduction of negative affect in healthy individuals. The results of the study are in line with a bidirectional symptom perception model and underline the crucial role of affect regulation in the processing of health-related information.
