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Creating Placebo Nonresponders in the Lab.
Fabrizio Benedetti1, Claudia Arduino2, Aziz Shaibani3
1University of Turin Medical School, Neuroscience Department, Turin, Italy; Innovative Clinical Training, Trials & Healthcare Initiative, Zermatt, Switzerland.
The Journal of Pain
|October 31, 2023
Summary
Mismatch conditioning, where experiences contradict expectations, can abolish placebo analgesia. This study demonstrates that creating placebo nonresponders is possible by disrupting expectations, with effects extending beyond the local application site.
Area of Science:
- Neuroscience
- Psychology
- Pain Research
Background:
- Placebo analgesia is primarily driven by conditioning and expectation mechanisms.
- These mechanisms can interact, with conditioning potentially amplifying expectations.
- Research has explored potentiating placebo effects but less so on mismatching conditioning and expectations.
Purpose of the Study:
- To investigate the effects of mismatching conditioning and expectations on placebo analgesia.
- To determine if incongruent associations can disrupt placebo responses.
- To explore the generalization of mismatch conditioning effects.
Main Methods:
- Participants underwent a conditioning procedure with incongruent associations, where expected pain relief was contradicted by increased painful stimulation.
- Verbal instructions suggested pain decrease with placebo, but actual experience involved heightened pain.
- Two pairings of these incongruent associations were administered, followed by pain threshold measurements.
Main Results:
- Mismatch conditioning significantly disrupted expectations of analgesia and abolished the placebo effect.
- The effects of local mismatch conditioning on the hand extended to the contralateral arm.
- Mismatch conditioning also affected a different pain type (tourniquet pain), indicating systemic effects.
- Expectations consistently predicted the magnitude of placebo analgesia.
Conclusions:
- Placebo nonresponders can be experimentally induced by manipulating expectations through mismatch conditioning.
- Local mismatch conditioning can lead to generalized effects on other body parts and pain types.
- Expectations play a critical role in therapeutic outcomes, with significant implications for clinical trial design.
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