Examining the role of expectancies during a mind-body intervention for hot flash reduction in postmenopausal women : is the relationship between treatment condition and symptom improvement mediated by response expectancy?

Hypnotherapy has been shown to be an effective intervention for the treatment of a variety of physical and psychological symptoms. However, the mechanisms of action responsible for hypnotherapy’s beneficial effects are not yet fully understood. One social cognitive perspective suggests that improvement can be attributed to changes in response expectancy. However, this theory has been widely debated, as studies investigating response expectancy as a mediator of the beneficial effects of hypnotherapy have produced mixed results. During this study, data collected from a sample of 172 postmenopausal women who had been randomized to a five-week hypnosis intervention or a structured attention control group were analyzed to determine if the relationship between group assignment and the number of hot flash reported by participants was mediated by expectancies for treatment efficacy. A series of simple mediation and conditional process analyses were used to test the significance of the indirect and direct effect of group assignment on hot flash frequency. Results did not support mediation of the relationship between treatment condition and hot flash frequency through response expectancy. This was true for all models tested in the analyses, including those that both did and did not account for the potential moderating role of hypnotizability. Secondary analysis suggested that hypnotizability was a moderator of the direct effect of group assignment on hot flash frequency. Furthermore, results suggested that participants were more likely to practice self-hypnosis when they were experiencing a greater number of hot flashes. Together, these results suggest that changes in response expectancy did not account for symptom improvement during a hypnosis intervention for hot flashes. Future studies should seek to determine whether alternative theories offer a more probable explanation. Efforts should also be made to uncover additional mediating variables.