Can placebo or nocebo pills improve or impair cognition performance?

Abstract

Objective: Although the placebo effect is well known to affect many behaviors, the effects on cognitive performance are less well investigated. Methods: In this study, the effects of a placebo and a nocebo manipulation on cognitive performance was investigated in healthy young participants in an unblinded between-subjects study. In addition, the participants were asked about their subjective experience in the placebo and nocebo condition. Results: The data suggested that the placebo condition induced the feeling of being more attentive and more motivated and the nocebo condition induced a feeling of being less attentive and alert and that they performed less well than normal. However, no placebo or nocebo effects were found on the actual performance on word learning, working memory, Tower of London task, or spatial pattern separation. Conclusions: These findings further support the notion that placebo or nocebo effects are not likely to occur in young healthy volunteers. However, other studies suggest that placebo effects can be found in implicit memory tasks and in participants with memory problems. Further placebo/nocebo studies are indicated using different experimental designs and different populations in order to better understand the placebo effect on cognitive performance.