Molecular classification of the placebo effect in nausea

Area of Science:

• Neuroscience
• Psychiatry
• Proteomics

Background:

• The placebo effect, a well-documented phenomenon, influences subjective and objective health outcomes.
• Understanding the biological underpinnings of the placebo effect is crucial for therapeutic advancements.

Purpose of the Study:

• To investigate whether plasma proteins can serve as biomarkers for monitoring and predicting placebo effects.
• To identify specific plasma proteins associated with placebo responses in a controlled setting.

Main Methods:

• A randomized controlled trial involving 90 participants exposed to a nauseating stimulus.
• Plasma protein profiling using label-free tandem mass spectrometry.
• Gene ontology (GO) enrichment analysis and Receiver Operator Characteristics (ROC) analysis.

Main Results:

• Significant placebo effects were observed on nausea, motion sickness, and gastric activity (in females).
• 74 differentially regulated plasma proteins were identified as correlates of the placebo effect.
• GO analysis revealed involvement of acute-phase and microinflammatory proteins; identified signatures predicted nausea scores.
• ROC analysis identified specific proteins, including immunoglobulins and complement activation proteins, differentiating responders from non-responders.

Conclusions:

• Plasma proteomics is a viable approach for identifying molecular correlates and predictors of the placebo effect.
• The findings suggest that inflammatory and immune pathways are implicated in the placebo response.
• This study provides a foundation for developing objective biomarkers for placebo effects.