title: The effects of manipulating expectations through placebo and nocebo administration on gastric tachyarrhythmia and motion-induced nausea.
abstract: BACKGROUND
  Interest in the role of expectation in the development of nausea and other adverse conditions has existed for decades. The purpose of this study was to examine the effects of manipulating expectations through the administration of placebos and nocebos on nausea and gastric tachyarrhythmia provoked by a rotating optokinetic drum.
  
  
  METHODS
  Seventy-five participants were assigned to one of three groups. Positive-expectancy group participants were given placebo pills that would allegedly protect them against the development of nausea and motion sickness. Negative-expectancy group participants were given the same pills as nocebos; they were led to believe there was a tendency for them to make nausea somewhat worse. Placebo-control group participants were told the pills were indeed placebos that would have no effect whatsoever.
  
  
  RESULTS
  Subjective symptoms of motion sickness were significantly lower among negative-expectancy group participants than positive-expectancy and placebo-control group participants (p<0.05). Gastric tachyarrhythmia, the abnormal stomach activity that frequently accompanies nausea, was also significantly lower among negative-expectancy group participants than positive-expectancy and Placebo-Control Group participants during drum rotation (p<.05) [corrected]
  
  
  CONCLUSIONS
  Inducing negative expectations through nocebo administration reduced nausea and gastric dysrhythmia during exposure to provocative motion, whereas positive placebos were ineffective for preventing symptom development. That manipulation of expectation affected gastric physiological responses as well as reports of symptoms, suggests an unspecified psychophysiological mechanism was responsible for the observed group differences. These results also suggest that patients preparing for difficult medical procedures may benefit most from being provided with detailed information about how unpleasant their condition may become.
authors.affiliation: Wake Forest University School of Medicine, Department of Internal Medicine, Section of Gastroenterology, Medical Center Boulevard, Winston-Salem, North Carolina 27157, USA. mlevine@wfubmc.edu
authors.forename: Max E
authors.initials: ME
authors.lastname: Levine
authors.forename: Robert M
authors.initials: RM
authors.lastname: Stern
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Koch
mesh_terms: D000293:Adolescent; D000328:Adult; D000932:Antiemetics / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008297:Male; D009041:Motion Sickness / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology* / Q000523:psychology; D016065:Myoelectric Complex, Migrating / Q000502:physiology; D009325:Nausea / Q000188:drug therapy* / Q000209:etiology / Q000523:psychology; D015990:Placebo Effect; D013272:Stomach Diseases / Q000503:physiopathology
chemical_list: D000932:Antiemetics