Placebo and nocebo effects are positive or negative treatment effects respectively, unrelated to the treatment mechanism, which are induced by patients’ expectations. Placebo and nocebo effects are... Show morePlacebo and nocebo effects are positive or negative treatment effects respectively, unrelated to the treatment mechanism, which are induced by patients’ expectations. Placebo and nocebo effects are known to play a role in treatment effects for various symptoms and conditions, especially in the field of pain. The aim of the current disseration was to increase understanding of placebo and nocebo effects on itch.The results of the studies presented in this thesis further underline that placebo and nocebo effects play a role in itch perception. We found that itch is highly susceptible to suggestions and placebo and nocebo effects can be induced on itch by verbal suggestion and conditioning. Most notably, our findings show for the first time that particularly the combination of conditioning with verbal suggestion is most promising for inducing both placebo and nocebo effects on itch, which is in accordance with placebo research on pain. Moreover, a new and promising finding is that counterconditioning has shown to reverse nocebo effects on itch. Future research may build upon the findings of this thesis to further enlarge our knowledge on placebo and nocebo effects on itch and how to maximize or minimize them, respectively, also in a clinical setting, to eventually optimize available interventions for patients suffering from chronic itch. Show less
Häufig erfahren Patienten positive (Placebo) oder negative (Nocebo) Behandlungseffekte aufgrund ihrer eigenen positiven oder negativen Erwartungen gegenüber der Behandlung. Die systematische... Show moreHäufig erfahren Patienten positive (Placebo) oder negative (Nocebo) Behandlungseffekte aufgrund ihrer eigenen positiven oder negativen Erwartungen gegenüber der Behandlung. Die systematische Erforschung dieser Placebo- und Noceboeffekte bei Pruritus hat erst in den letzten Jahren vermehrt Aufmerksamkeit erfahren. Experimentelle Studien belegen, dass Placebo- und Noceboeffekten bei Pruritus wie auch bei anderen Symptomen (z. B. Schmerz) Lernprozesse wie verbale Suggestionen und Konditionierung zugrunde liegen. Untersuchungen zum Phänomen „übertragbares Jucken“ zeigen, dass Beobachtungslernen bei Pruritus eine wichtige Rolle spielt, und suggerieren des Weiteren eine erhöhte Empfindlichkeit von Pruritus für Suggestionen und somit Placebo- und Noceboeffekte. Substanzielle Reduktionen von Pruritus in den Placebogruppen klinischer Studien implizieren, dass Placeboeffekte auch im klinischen Bereich eine maßgebliche Bedeutung haben. Der vorliegende Beitrag bietet eine Übersicht, wie Placebo- und Noceboeffekte bei Pruritus im wissenschaftlichen Bereich und im klinischen Alltag eingesetzt werden können. Show less
Nocebo effects, i.e. reduced treatment effects due to patients’ negative expectations, play a role in itch. Recent studies have shown that nocebo effects can be induced experimentally on itch and... Show moreNocebo effects, i.e. reduced treatment effects due to patients’ negative expectations, play a role in itch. Recent studies have shown that nocebo effects can be induced experimentally on itch and also be minimized and even turned into the opposite direction, i.e. placebo effects. It is not known whether these effects generalize to itch-associated scratching behaviour. The aim of this study was to determine whether induction and reversal of nocebo effects on itch evoked by electrical and histamine stimuli generalized to scratching. Ninety-seven healthy participants were included in the study. The manipulation was successful, as during the nocebo learning phase, increased scratching responses were found for higher intensity compared with lower intensity itch stimuli. During the testing phase of induction or reversal of the nocebo effects, however, no significant nocebo effects or reversed nocebo effects, were found in scratching. Thus, no straightforward generalization of nocebo effects from itch to scratching was found in this laboratory setting. Further investigation into possible generalization is needed in different settings and in patients with chronic itch. Show less
