Exploring the Contribution of Expectancy, Anxiety, and Attention to Nocebo Effects

Abstract

There is a growing body of evidence demonstrating the ubiquity of the nocebo effect across symptoms, treatments, and clinical settings. However, there is currently limited investigation of potential moderating or mediating psychological factors involved in nocebo effects. Thus, the central aim of this project was to better understand three psychological factors proposed to be involved in nocebo effects: expectancy, anxiety, and attention. All experimental Chapters (4, 6, 7) found strong evidence for expectancy as a mediator of the effect of learning on nocebo hyperalgesia. There was some evidence that state anxiety may have a weak mediating effect on nocebo experience. When investigated as a moderator, state anxiety may facilitate enhanced pain or symptom experience, rather than nocebo hyperalgesia specifically. Chapter’s 4 and 7 found some evidence that pain catastrophising, or pain-related dispositional anxiety, may moderate nocebo hyperalgesia. Taken together, the findings of the present thesis suggest that expectancy and anticipatory anxiety are core mediating factors in nocebo effects. There was no strong evidence for any of the proposed moderating factors (attention, state, dispositional anxiety). Thus, psychological mechanisms induced by nocebo learning are of primary importance to the occurrence of nocebo effects, and must be appropriately targeted. The theoretical and clinical implications, directions for future research and general limitations of the present thesis are discussed in the final chapter.