Generalization of placebo and nocebo effects on somatosensory sensations

Abstract

Carryover of previous treatment outcomes to subsequent medical treatment outcomes seems to be pervasive. The influence of a treatment history can generalize across treatments and across symptoms. These generalization effects in clinical practice have been studied experimentally in placebo and nocebo effects, which are beneficial and adverse effects that do not arise from active treatment components, respectively. The aim of this thesis was to answer the question of whether previously learned placebo and nocebo effects can generalize within and across somatosensory sensations. Additionally, the thesis also explored the role of individual characteristics as predictors (e.g., anxiety, stress, attention, catastrophizing) for the generalization of placebo and nocebo effects. The findings of the thesis have showed that placebo and nocebo effects can generalize within pain and itch modalities, but can not generalize from pain to itch and from itch to touch. The generalization effects of placebo and nocebo effects can not be predicted by psychological characteristics (e.g., anxiety- and stress symptoms) in healthy individuals. Moreover, the dissertation addresses the limitations of the work and directions for future research, as well as giving implications for clinic practice.