Placebo/Nocebo Effect Flashcards
Positive non-specific or contextual effects of therapy
Placebo
Negative non-specific or contextual effects of therapy
Nocebo
Sham surgery, sham acupuncture, sham injections, and placebo topical therapies are more effective than
Pill placebos
By comparison, there is a very small placebo response in
Dichotomous/binary outcomes
Provides half or more of the medication benefit, especially for pain and depression
Placebo effect
Up to 30% of patients discontinue placebo due to
Side effects
The response to pain placebos is blocked by
naloxone (narcotic blocker) and rimonabant (cannabinoid blocker)
Parkinson pill placebos and sham surgery cause changes in functional
MRI
Cause changes in brain metabolic activity on functional MRI
Anti-depressant and pain placebos
Decreased the placebo effect and increased the “nocebo” (rebound) effect
Higher anxiety
COMT polymorphism with higher synaptic dopamine levels predicts “augmented” response of
Placebos
Depression and anxiety lower the
Pain placebo response
The pain nocebo response appears to be mediated by
Anxiety (treated by Valium) and CCK
Really need a placebo arm, vs. an untreated arm, to be considered valid
Studies with a graded, subjective outcome
May have less need for a placebo arm, as these are less influenced by placebo mechanisms
Studies with major objective, dichotomous outcomes (e.g. death)
A placebo is unethical in a study when a credible placebo would be too risky. For example, in a
Sternotomy
Used to distinguish between organic and psychogenic symptoms
Placebos
The majority of medication side effects have nothing to do with the
Medication
Is it ever appropriate to lie about what medication is patient is getting?
No
Positive expectation-setting and positive/empathic demeanor are
Desireable
Responsible for a large fraction of the placebo response
Physician-patient relationship
