Caffeine and theanine exert opposite effects on attention (2017)
Tea is perceived as more relaxing than coffee, even though both contain caffeine. Consumed together, caffeine and theanine exert similar cognitive effects to that of caffeine alone, but exert opposite effects on arousal, in that caffeine accentuates and theanine mitigates physiological and felt stress responses. We evaluated whether caffeine and theanine influenced cognition under emotional arousal. Caffeine accentuated global processing of visual attention on the hierarchical shape task, theanine accentuated local processing, and the combination did not differ from placebo. Caffeine reduced flanker conflict difference scores on the Attention Network Test, theanine increased difference scores, and the combination did not differ from placebo. Thus, under emotional arousal, caffeine and theanine exert opposite effects on certain attentional processes, but when consumed together, they counteract the effects of each other. Keywords: arousal; attention; caffeine; caféine; cognition; cortisol; emotion; fonctions cognitives; theanine; théanine; émotion; éveil.