This is strong, clear and very persuasive evidence that Kennedy was speaking of an outcome that had been totally generated by a subject's negative expectation of a drug or ritual's administration, which was the exact counterpart of a placebo response that would have been generated by a subject's positive expectation.[according to whom?]
Finally, and most definitely, Kennedy was not speaking of an active drug's unwanted but pharmacologically predictable negative side effects (something for which the term nocebo is being increasingly used in current literature).[citation needed]
For example, verbal suggestions of pain induce anxiety, which in turn causes the release of cholecystokinin, which facilitates pain transmission.[10]
Effects[edit]
Side effects of drugs[edit]
It has been shown that, due to the nocebo effect, warning patients about side effects of drugs can contribute to the causation of such effects, whether the drug is real or not.[11][12] This effect has been observed in clinical trials: according to a 2013 review, the dropout rate among placebo-treated patients in a meta-analysis of 41 clinical trials of Parkinson's disease treatments was 8.8%.[13] A 2013 review found that nearly 1 out of 20 patients receiving a placebo in clinical trials for depression dropped out due to adverse events, which were believed to have been caused by the nocebo effect.[14] Lifestar Note pertaining to television drug commercials.
Electromagnetic hypersensitivity[edit]
Evidence suggests that the symptoms of electromagnetic hypersensitivity are caused by the nocebo effect.[15][16]
Pain[edit]
Verbal suggestion can cause hyperalgesia (increased sensitivity to pain) and allodynia (perception of a tactile stimulus as painful) as a result of the nocebo effect.[17] Nocebo hyperalgesia is believed to involve the activation of cholecystokinin receptors.[18]
Ambiguity of medical usage[edit] In a paper,[19] Stewart-Williams and Podd argue that using the contrasting terms "placebo" and "nocebo" to label inert agents that produce pleasant, health-improving, or desirable outcomes versus unpleasant, health-diminishing, or undesirable outcomes (respectively), is extremely counterproductive.
For example, precisely the same inert agents can produce analgesia and hyperalgesia, the first of which, from this definition, would be a placebo, and the second a nocebo.[20]
A second problem is that the same effect, such as immunosuppression, may be desirable for a subject with an autoimmune disorder, but be undesirable for most other subjects. Thus, in the first case, the effect would be a placebo, and in the second, a nocebo.[19]
A third problem is that the prescriber does not know whether the relevant subjects consider the effects that they experience to be desirable or undesirable until some time after the drugs have been administered.[19]
A fourth problem is that the same phenomena are being generated in all the subjects, and these are being generated by the same drug, which is acting in all of the subjects through the same mechanism. Yet because the phenomena in question have been subjectively considered to be desirable to one group but not the other, the phenomena are now being labeled in two mutually exclusive ways (i.e., placebo and nocebo); and this is giving the false impression that the drug in question has produced two different phenomena.[19]