title: Expectancy-induced placebo analgesia in children and the role of magical thinking.
abstract: Expectations and beliefs shape the experience of pain. This is most evident in context-induced, placebo analgesia, which has recently been shown to interact with the trait of magical thinking (MT) in adults. In children, placebo analgesia and the possible roles that MT and gender might play as modulators of placebo analgesia have remained unexplored. Using a paradigm in which heat pain stimuli were applied to both forearms, we investigated whether MT and gender can influence the magnitude of placebo analgesia in children. Participants were 49 right-handed children (aged 6-9 years) who were randomly assigned-stratified for MT and gender-to either an analgesia-expectation or a control-expectation condition. For both conditions, the placebo was a blue-colored hand disinfectant that was applied to the children's forearms. Independent of MT, the placebo treatment significantly increased both heat pain threshold and tolerance. The threshold placebo effect was more pronounced for girls than boys. In addition, independent of the expectation treatment, low-MT boys showed a lower tolerance increase on the left compared to the right side. Finally, MT specifically modulated tolerance on the right forearm side: Low-MT boys showed an increase, whereas high-MT boys showed a decrease in heat pain tolerance. This study documented a substantial expectation-induced placebo analgesia response in children (girls > boys) and demonstrated MT and gender-dependent laterality effects in pain perception. The findings may help improve individualized pain management for children.
  
  
  CONCLUSIONS
  The study documents the first experimental evidence for a substantial expectancy-induced placebo analgesia response in healthy children aged 6 to 9 years (girls > boys). Moreover, the effect was substantially higher than the placebo response typically found in adults. The findings may help improve individualized pain management for children.
authors.affiliation: Department of Psychology, Clinical Psychology and Psychotherapy, University of Basel, Basel, Switzerland; Collegium Helveticum, University of Zurich and ETH Zurich, Zurich, Switzerland; brainability LLC, Zurich, Switzerland. Electronic address: krummenacher@collegium.ethz.ch.
authors.forename: Peter
authors.initials: P
authors.lastname: Krummenacher
authors.affiliation: Department of Psychology, Clinical Psychology and Psychotherapy, University of Basel, Basel, Switzerland; Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts; Program in Placebo Studies, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, Massachusetts.
authors.forename: Joe
authors.initials: J
authors.lastname: Kossowsky
authors.affiliation: Department of Psychology, Clinical Psychology and Psychotherapy, University of Basel, Basel, Switzerland.
authors.forename: Caroline
authors.initials: C
authors.lastname: Schwarz
authors.affiliation: Neuropsychology Unit, Department of Neurology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Brugger
authors.affiliation: Program in Placebo Studies, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, Massachusetts; Psychiatry Department, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts; Psychology Department, Endicott College, Beverly, Massachusetts.
authors.forename: John M
authors.initials: JM
authors.lastname: Kelley
authors.affiliation: Department of Psychology, Clinical Psychology and Epidemiology, University of Basel, Switzerland.
authors.forename: Andrea
authors.initials: A
authors.lastname: Meyer
authors.affiliation: Department of Psychology, Clinical Psychology and Psychotherapy, University of Basel, Basel, Switzerland.
authors.forename: Jens
authors.initials: J
authors.lastname: Gaab
mesh_terms: D000698:Analgesia / Q000523:psychology*; D059031:Anticipation, Psychological / Q000502:physiology*; D001007:Anxiety / Q000503:physiopathology; D002648:Child; D005260:Female; D005542:Forearm; D007839:Functional Laterality; D006358:Hot Temperature; D006801:Humans; D008297:Male; D010146:Pain / Q000503:physiopathology / Q000523:psychology; D010147:Pain Measurement; D058748:Pain Perception / Q000502:physiology*; D017288:Pain Threshold / Q000502:physiology; D010551:Personality / Q000502:physiology*; D010812:Physical Stimulation / Q000009:adverse effects; D015990:Placebo Effect; D012727:Sex Characteristics; D011795:Surveys and Questionnaires
keywords: Placebo analgesia; children; expectation; magical thinking; pain