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Placebo and Nocebo responses, cortisol, and circulating beta-endorphin
Oddmund Johansen1, Jan Brox, Magne Arve Flaten
1Department of Orthopedic Surgery, The University Hospital of North Norway, Norway.
Psychosomatic Medicine
|September 26, 2003
Summary
The placebo effect reduced pain perception, but was not linked to stress hormones like cortisol or beta-endorphin. Conversely, nocebo expectations increased cortisol but did not alter pain levels.
Area of Science:
- Psychoneuroimmunology
- Pain Perception Research
Background:
- Placebo and nocebo effects significantly influence subjective experiences, including pain.
- The role of stress modulation, specifically cortisol and beta-endorphin, in these responses remains incompletely understood.
Purpose of the Study:
- To investigate whether placebo and nocebo responses in pain perception are mediated by stress modulation.
- To examine the relationship between pain ratings and levels of cortisol and beta-endorphin.
Main Methods:
- Healthy volunteers (N=59) underwent ischemic pain induction.
- Participants were assigned to placebo (pain relief expectation), nocebo (pain increase expectation), or natural history (control) groups.
- Pain ratings and blood samples for cortisol and beta-endorphin were collected post-intervention.
Main Results:
- A significant placebo effect was observed, with lower pain ratings in the placebo group compared to controls.
- Cortisol levels increased across all groups, with the most substantial rise in the nocebo group.
- Beta-endorphin levels also increased in all groups; however, pain ratings did not correlate with either cortisol or beta-endorphin levels.
Conclusions:
- The placebo response, characterized by reduced pain, was evident but not associated with stress markers (cortisol) or beta-endorphin.
- Nocebo expectations elevated cortisol levels, but this hormonal change did not influence the perceived pain intensity.