title: Inducing Expectations for Health: Effects of Verbal Suggestion and Imagery on Pain, Itch, and Fatigue as Indicators of Physical Sensitivity.
abstract: Research into placebo effects has convincingly shown that inducing positive outcome expectations can reduce pain and other physical sensations. However, the comparative effects of different expectation inductions, such as verbal suggestion or mental imagery, and their generic effects on physical sensitivity, to different sensations such as pain, itch, and fatigue, are still largely unknown. In the current study, we assessed the individual and combined effects of verbal suggestion and imagery on pain, itch, and fatigue as indicators of physical sensitivity in a randomized study design. Healthy participants (n = 116) were given an inert (placebo) capsule that was said to be effective for reducing physical sensitivity in either the majority (positive verbal suggestion) or the minority (control verbal suggestion) of users. Subsequently, they imagined either their best possible health (positive imagery) or a typical day (control imagery). Sensitivity to pain, itch, and fatigue was tested using a cold pressor test, histamine iontophoresis, and a bicycle test, respectively. Heart rate and skin conductance were recorded continuously. Results showed that positive verbal suggestion and imagery successfully induced positive expectations, but they did not affect physical sensitivity, as indicated by sensitivity to pain, itch, or fatigue, or concurrent physiological responses. These results could indicate that the specificity and concreteness of expectation inductions might be important for their applicability in the treatment of physical symptoms.
  
  
  BACKGROUND
  Nederlands Trial Register NTR3641.
authors.affiliation: Unit Health, Medical and Neuropsychology, Leiden University, Leiden, the Netherlands; Leiden Institute for Brain and Cognition, Leiden University, Leiden, the Netherlands; Department of Medical Psychology, Radboudumc, Nijmegen, the Netherlands.
authors.forename: Kaya J
authors.initials: KJ
authors.lastname: Peerdeman
authors.affiliation: Unit Health, Medical and Neuropsychology, Leiden University, Leiden, the Netherlands; Leiden Institute for Brain and Cognition, Leiden University, Leiden, the Netherlands; Department of Medical Psychology, Radboudumc, Nijmegen, the Netherlands.
authors.forename: Antoinette I M
authors.initials: AI
authors.lastname: van Laarhoven
authors.affiliation: Department for Health Evidence, Radboudumc, Nijmegen, the Netherlands.
authors.forename: A Rogier T
authors.initials: AR
authors.lastname: Donders
authors.affiliation: Department of Physiology, Radboudumc, Nijmegen, the Netherlands.
authors.forename: Maria T E
authors.initials: MT
authors.lastname: Hopman
authors.affiliation: Department of Clinical Psychological Science, Maastricht University, Maastricht, the Netherlands.
authors.forename: Madelon L
authors.initials: ML
authors.lastname: Peters
authors.affiliation: Unit Health, Medical and Neuropsychology, Leiden University, Leiden, the Netherlands; Leiden Institute for Brain and Cognition, Leiden University, Leiden, the Netherlands; Department of Medical Psychology, Radboudumc, Nijmegen, the Netherlands.
authors.forename: Andrea W M
authors.initials: AW
authors.lastname: Evers
mesh_terms: D000293:Adolescent; D003080:Cold Temperature; D004562:Electrocardiography; D015444:Exercise; D005221:Fatigue / Q000503:physiopathology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006632:Histamine / Q000494:pharmacology; D006801:Humans; D019018:Imagery, Psychotherapy; D008297:Male; D010146:Pain / Q000503:physiopathology*; D015990:Placebo Effect; D011537:Pruritus / Q000503:physiopathology*; D012867:Skin / Q000187:drug effects; D012879:Skin Physiological Phenomena; D013404:Suggestion; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D006632:Histamine