Effects of Ginger and Expectations on Symptoms of Nausea in a Balanced Placebo Design

Abstract

ObjectiveGinger effects on (experimental) nausea have been described, but also strong placebo effects and sex differences when nausea is involved. The “balanced placebo design” has been proposed to allow better separation of drug and placebo effects.MethodsSixty-four healthy participants (32 women) were randomly assigned to receive an antiemetic ginger preparation or placebo, and half of each group was told to have received drug or placebo. They were exposed to 5×2 min body rotations to induce nausea. Subjective symptoms and behavioral (rotation tolerance, head movements) and physiological measures (electrogastrogram, cortisol) were recorded. Groups were balanced for sex of participants and experimenters.ResultsGinger and the information given did not affect any outcome measure, and previous sex differences could not be confirmed. Adding the experimenters revealed a significant four-factorial interaction on behavioral but not on subjective or physiological measures Men who received placebo responded to placebo information when provided by the male experimenter, and to ginger information when provided by the female experimenter. This effect was not significant in women.ConclusionThe effects of an antiemetic drug and provided information interact with psychosocial variables of participants and experimenters in reports of nausea.

Neuro-Bio-Behavioral Mechanisms of Placebo and Nocebo Responses: Implications for Clinical Trials and Clinical Practice

“…Changing expectations about nausea has been accomplished in laboratory experiments by the intake of placebo pills (Levine et al, 2006) or by delivering positive suggestions associated with distinct gustatory stimuli Weimer et al, 2012). Other studies attempting to modify expectations have provided counterintuitive, i.e., reverse effects of suggestions (Levine et al, 2006) or negative results (Williamson et al, 2004).…”

“…Other studies attempting to modify expectations have provided counterintuitive, i.e., reverse effects of suggestions (Levine et al, 2006) or negative results (Williamson et al, 2004). These inconsistencies may in part be explained by sex differences Weimer et al, 2012) and/or complex interactions between the participant's sex and that of the experimenter (Aslaksen et al, 2007;Weimer et al, 2012). Ultimately, interventions combining the principles of conditioning with optimized expectations may be most promising for effective alleviation of nausea symptoms.…”

“…Studies have suggested that expectancies affect both the behavioral effects of nausea and induce changes in gastric slow-wave rhythm as measured by electrogastrography (Williamson et al, 2004). However, there is a paucity of findings and many are somewhat contradictory (Levine et al, 2006;Weimer et al, 2012;Horing et al, 2013).…”

How to Study Placebo Responses in Motion Sickness with a Rotation Chair Paradigm in Healthy Participants

“…Participants gave written informed consent prior to inclusion, and complete disclosure of the study purpose was offered to all participants after completion of the study 17 .…”

“…This mismatch leads to a series of vegetative symptoms like nausea, vertigo, sweating, or tiredness but also to changes in gastric myoelectrical activity 12,13 , and can be evoked in most healthy participants depending on the strength of the stimulus 14 . We have already repeatedly employed this rotation chair paradigm to induce motion sickness to investigate mediators 15 and placebo and nocebo responses [16][17][18] . In this paradigm, healthy participants are seated in a rotating chair, have to wear an eye mask and earphones to reduce the ability to orientate themselves during the rotation procedure, and to move their head slowly up and down.…”