Different Disclosed Probabilities to Receive an Antiemetic Equally Decrease Subjective Symptoms in an Experimental...

Area of Science:

• Neuroscience
• Psychology
• Gastroenterology

Background:

• Nausea is a common symptom with various causes.
• Placebo effects, particularly in pain and nausea, are well-documented.
• Understanding the mechanisms behind placebo responses is crucial for therapeutic development.

Purpose of the Study:

• To investigate if the communicated probability of receiving an antiemetic influences nausea.
• To explore the role of expectations and psychological factors in nausea placebo responses.

Main Methods:

• Healthy participants underwent nauseogenic stimuli.
• Participants were randomized to receive 0%, 50%, or 100% disclosed probability of an antiemetic (all received placebo).
• Nausea was assessed via subjective, behavioral, and physiological measures (electrogastrogram).

Main Results:

• Both 100% and 50% probability groups reported significantly less nausea than the 0% group.
• This placebo effect on nausea was not observed in behavioral or physiological measures.
• Women showed a greater susceptibility to the placebo effect in this study.

Conclusions:

• Nausea is responsive to placebo effects, irrespective of disclosed antiemetic probability or explicit expectations.
• The findings suggest central mechanisms, potentially linked to reward pathways and social interaction, underlie these placebo responses.
• This highlights the significant impact of psychological factors on physiological symptoms like nausea.