title: Induction of nocebo and placebo effects on itch and pain by verbal suggestions.
abstract: Physical complaints, such as pain, can be effectively reduced by placebo effects through induction of positive expectations, or increased by nocebo effects through induction of negative expectations. In the present study, verbally induced nocebo and placebo effects on itch were experimentally investigated for the first time. In part 1, the role of verbal suggestions in inducing nocebo effects on itch and pain was investigated. All subjects received the same somatosensory quantitative sensory testing stimuli, that is, mechanical and electrical stimuli and application of histamine, and verbal suggestions to manipulate expectations regarding the stimuli. The suggestions were designed to produce either high expectations for itch (itch nocebo) or pain (pain nocebo) or low expectations for itch (itch nocebo control) or pain (pain nocebo control). Results showed that high itch and pain expectations resulted in higher levels of itch and pain, respectively. When comparing nocebo effects, induced by verbal suggestions, results were more pronounced for itch than for pain. In part 2, verbal suggestions designed to produce a placebo effect on itch (itch placebo) or pain (pain placebo), or neutral suggestions (itch placebo control and pain placebo control) were given regarding a second application of histamine and compared with the first application applied in part 1. Results of placebo effects only showed a significantly larger decrease in itch in the itch placebo condition than in the pain placebo condition. In conclusion, we showed for the first time that nocebo and possibly placebo responses can be induced on itch by verbal suggestions.
authors.affiliation: Department of Medical Psychology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands Pain and Nociception Neuroscience Research Group, Department of Anaesthesiology, Pain and Palliative Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands Department of Rheumatology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands Department of Dermatology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: Antoinette I M
authors.initials: AIM
authors.lastname: van Laarhoven
authors.forename: Michiel L
authors.initials: ML
authors.lastname: Vogelaar
authors.forename: Oliver H
authors.initials: OH
authors.lastname: Wilder-Smith
authors.forename: Piet L C M
authors.initials: PLCM
authors.lastname: van Riel
authors.forename: Peter C M
authors.initials: PCM
authors.lastname: van de Kerkhof
authors.forename: Floris W
authors.initials: FW
authors.lastname: Kraaimaat
authors.forename: Andrea W M
authors.initials: AWM
authors.lastname: Evers
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D004311:Double-Blind Method; D005260:Female; D006632:Histamine / Q000009:adverse effects; D017442:Histamine Agonists / Q000009:adverse effects; D006801:Humans; D007092:Imagination; D008297:Male; D010146:Pain / Q000209:etiology / Q000523:psychology*; D059408:Pain Management; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology; D010552:Personality Assessment; D010812:Physical Stimulation / Q000009:adverse effects; D015990:Placebo Effect; D010919:Placebos / Q000627:therapeutic use; D011537:Pruritus / Q000523:psychology* / Q000628:therapy*; D057566:Self Report; D012928:Social Desirability; D013404:Suggestion; D011795:Surveys and Questionnaires; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D017442:Histamine Agonists; D010919:Placebos; D006632:Histamine