3. Placebo Effect
Placebo Effect
Our resources on Placebo Effect
   The placebo effect is a poorly understood phenomenon but recent work
   suggests that placebo represents the psychosocial aspect of every
   treatment and "the study of placebo is essentially the study of
   of a placebo include the anterior cingulate cortex, dorsolateral
   The placebo effect needs to be taken into account in clinical trials:
     * In certain settings placebo interventions can influence
       is difficult to distinguish patient-reported effects of placebo
       from biased reporting. Variations in the effect of placebo were
   It is important therefore to differentiate between the placebo effect
   difference between a perceived placebo effect and a true placebo effect
Perceived placebo effect
   This is seen in the placebo arm of a clinical trial, eg new
   but this may not be true placebo effect as other factors may confound
       reduce over time, thus exaggerating the placebo effect.
       pressure measured, which would increase the apparent placebo
True placebo effect
   active and placebo treated groups. These are relatively uncommon but it
     * Placebo treatment is more effective in relieving pain compared with
       (placebo was given to sleeping patients and no difference noted).
     * Physical placebos, eg invasive techniques such as injection, are
       more powerful than simple oral placebos.^[7]
     * Topical placebo is also more effective than oral placebo, eg in
     * There is no standard degree of placebo effect (approximately 30% is
     * Placebo effects on pain are generally greater than on other
     * Placebo effects are not always useful and may produce adverse
     * Variations in placebo remission and response rates reported in
     * A study of osteoarthritis patients elicited that the placebo effect
       placebo was given through injections/needles.^[9]
     * One study found no difference in placebo effect whether the patient
     * A study of migraine patients found that placebos were more
    1. Koshi EB, Short CA; Placebo theory and its implications for
    2. Oken BS; Placebo effects: clinical aspects and neurobiology. Brain.
    3. Eickhoff JC; Placebo effect-adjusted assessment of quality of life
       in placebo-controlled clinical trials. Stat Med. 2008 Apr
    4. Hrobjartsson A, Gotzsche PC; Placebo interventions for all clinical
    5. Ernst E; Placebo: new insights into an old enigma. Drug Discov
    6. Asmar R, Safar M, Queneau P; Evaluation of the placebo effect and
    7. Diener HC; Placebo effects in treating migraine and other
    8. Garud S, Brown A, Cheifetz A, et al; Meta-analysis of the placebo
    9. Zhang W, Robertson J, Jones AC, et al; The placebo effect and its
   10. Musial F, Klosterhalfen S, Enck P; Placebo responses in patients
   11. Diener HC, Schorn CF, Bingel U, et al; The importance of placebo in