Nocebo effects are harmful treatment effects of an inert agent elicited by the anticipation of negative effects. Limited amount of studies focused on nocebo effects on pain, suggesting nocebo...Show moreNocebo effects are harmful treatment effects of an inert agent elicited by the anticipation of negative effects. Limited amount of studies focused on nocebo effects on pain, suggesting nocebo effects can increase pain sensations. Importantly, a better understanding of nocebo effects in relation to pain is needed due to its clinical relevance. Few studies showed that established nocebo effects can generalize to different stimuli, yet it has not been investigated that nocebo effects can occur from one modality to another within the category of pain sensations. Besides, research suggests personality factors such as anxiety can play a role in these nocebo effects. This study investigates nocebo effects on heat pain, its generalization to different pain stimuli, and as an explorative objective, we investigate the possible moderating role of anxiety in these effects. At first, the STAI-S questionnaire was assessed to measure the levels of anxiety per individual. To induce negative expectations, two nocebo inducing mechanisms were used; first, a conditioning phase related to heat pain was used to acquire an association between the activation of a sham device (ENS) and increased pain stimulation, secondly, verbal suggestion was used by informing participants the ENS will increase pain sensations. Then, heat pain stimuli set at the same temperature were assessed with the supposed activation and deactivation of the ENS. Thereafter, pressure pain stimuli at the same pressure were administered with the supposed activation/deactivation of the ENS. The results showed that participants experienced more heat pain and pressure pain with the supposed activation of the ENS. This demonstrates significant nocebo effect for heat pain, and it shows nocebo effects significantly generalized to pressure pain stimuli. However, for the explorative outcome, the moderation analysis did not find indications that anxiety played a role in these effects. The current findings suggests the important role of negative expectations interfering with pain perception and altering the experience of different pain stimuli. We discuss the importance to understand the less researched nocebo phenomenon and its generalization to effectively reduce nocebo effects in a clinical setting. Also, the need to explore psychological factors in these nocebo effects is emphasized.Show less
