title: Placebo-induced somatic sensations: a multi-modal study of three different placebo interventions.
abstract: Somatic sensations induced by placebos are a frequent phenomenon whose etiology and clinical relevance remains unknown. In this study, we have evaluated the quantitative, qualitative, spatial, and temporal characteristics of placebo-induced somatic sensations in response to three different placebo interventions: (1) placebo irritant solution, (2) placebo laser stimulation, and (3) imagined laser stimulation. The quality and intensity of evoked sensations were assessed using the McGill pain questionnaire and visual analogue scales (VAS), while subjects' sensation drawings processed by a geographic information system (GIS) were used to measure their spatial characteristics. We found that all three interventions are capable of producing robust sensations most frequently described as "tingling" and "warm" that can reach consider-able spatial extent (≤ 205 mm²) and intensity (≤ 80/100 VAS). Sensations from placebo stimulation were often referred to areas remote from the stimulation site and exhibit considerable similarity with referred pain. Interestingly, there was considerable similarity of qualitative features as well as spatial patterns across subjects and placebos. However, placebo laser stimulation elicited significantly stronger and more widespread sensations than placebo irritant solution. Finally, novelty seeking, a character trait assessed by the Temperament and Character Inventory and associated with basal dopaminergic activity, was less pronounced in subjects susceptible to report placebo-induced sensations. Our study has shown that placebo-induced sensations are frequent and can reach considerable intensity and extent. As multiple somatosensory subsystems are involved despite the lack of peripheral stimulus, we propose a central etiology for this phenomenon.
authors.affiliation: Somatosensory and Autonomic Therapy Research, Institute of Neuroradiology, Hannover Medical School, 30625, Hannover, Germany; Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, 02129, United States of America.
authors.forename: Florian
authors.initials: F
authors.lastname: Beissner
authors.affiliation: Pain & Autonomics - Integrative Research (PAIR), Department of Psychiatry and Psychotherapy, Jena University Hospital, 07743, Jena, Germany.
authors.forename: Franziska
authors.initials: F
authors.lastname: Brünner
authors.affiliation: Pain & Autonomics - Integrative Research (PAIR), Department of Psychiatry and Psychotherapy, Jena University Hospital, 07743, Jena, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Fink
authors.affiliation: Institute of Medical Psychology, Ludwig-Maximilians-University, 80336, Munich, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Meissner
authors.affiliation: Program in Placebo Studies, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 02215, United States of America.
authors.forename: Ted J
authors.initials: TJ
authors.lastname: Kaptchuk
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, 02129, United States of America; Department of Biomedical Engineering, Kyunghee University, Yongin, Korea.
authors.forename: Vitaly
authors.initials: V
authors.lastname: Napadow
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007834:Lasers; D008297:Male; D010146:Pain / Q000209:etiology; D010812:Physical Stimulation; D010919:Placebos; D012677:Sensation / Q000502:physiology*; D055815:Young Adult
chemical_list: D010919:Placebos