Placebo effects and the endocrine system: the role of oxytocin

Abstract

The aim of the current dissertation was to explore the link between the endocrine system and placebo effects with a focus on the hormone oxytocin. Two perspectives were examined: the possibility to elicit placebo effects in the endocrine system and influencing placebo and nocebo effects by hormones. In the first part of the dissertation possibility to induce placebo effects in the endocrine system with classical conditioning is explored. A systematic review of literature and the results of a large randomized controlled trial on classical conditioning of oxytocin are described in this part. In the second part of the dissertation we explored the possibility to influence placebo and nocebo effects with oxytocin. In this part results of two randomized controlled trials are presented. We demonstrated that there is accumulating evidence in the literature that placebo effects can be elicited in the endocrine system. Moreover, we described results of a randomized controlled trial in which we successfully conditioned oxytocin release. Finally, we showed a lack of evidence that oxytocin can influence placebo and nocebo effects.