Placebos, Suggestibility, and Hypnosis

In a twist on the use of placebos, a study was conducted with patients experiencing irritable bowel syndrome (IBS). They were explicitly ingormed that they would be receiving a placebo and it was suggested that the placebo had been shown in the past to relieve IBS symptoms through the mind-body healing process. The bottles containing the sugar pills were labeled "Placebo."


IBS is a disorder of the lower intestinal tract involving abdominal pain and abnormal bowel movements, and emotional stress or mood disorders, such as anxiety or depression, often make the symptoms worse.

Based on a self-reported questionnaire, the placebo group indicated significantly better pain relief and reduction in the severity of other symptoms compared to those who received routine treatment. The conclusion was that communication of a positive outcome was a factor in the effectiveness of the placebo and the suggestibility of the trial participants played a role.

Reports on the study can be found at the following URLs:

http://www.nytimes.com/2010/12/28/health/research/28perceptions.html?_r=1&ref=health

http://www.plosone.org/article/info:doi/10.1371/journal.pone.0015591

Ailments that involve subjective judgments by the patient such as "how do you feel" for depressive patients or "rank the intensity of your pain" for IBS sufferers tend to be particularly amenable to placebo treatments. In the case of stuttering, evaluations of treatment efficacy for relieving symptoms may be a bit more objective. A third party (neither treater nor treated) can, for example, count the number of disfluencies normalized on some word count or speaking time scale.

Nevertheless, since we have previously argued that stuttering is basically a mind-body problem, with a substantial mind contribution, we might very well expect that results of an "open knowledge" placebo trial for stutterers might have similar results as that for the IBS study.

On the other hand, some participants in the pagoclone trials have reported that their fluencies had deteriorated during periods when they (thought they) were switched to the placebo treatments. While these periods of disfluency might be attributed to fluency variations while they were on pagoclone, I would prefer to give the benefit of the doubt to the pagoclone trial participants at this point in time until the results of the trials are published. If, for example, previous periods of greater disfluency lasted typically for days or weeks, while the placebo was administered for months (during which disfluency persisted), then this would be evidence that the disfluency was attributable to the cessation of pagoclone treatment.

The world can be divided into two types: Those who are suggestible and those who are not. More accurately, the characteristic of suggestibility may lie on a spectrum--individuals are suggestible to varying degrees. The placebo response is thought, at least in part, to be based on individual differences in suggestibility. Those who are suggestible may be more responsive to medical treatments (real or placebo) on the basis of patient belief in addition to a possible physiological mechanism. If this is the case, then controlled double blind trials of medical treatments could be improved by either controlling for suggestibility or, in the extreme case, eliminating highly suggestible individuals from the trials through prescreening.

The personality characteristic of suggestibility may be difficult to measure objectively. However, the ease with which an individual can be hypnotized as well as the depth of the hypnosis might be taken as a proxy for suggestibility, although evaluating "hypnotizability" might be a relatively subjective endeavor.

The Mental Measurements Yearbook does not indicate the existence of any psychological tests for the personality characteristic of suggestibility. However, the Multidimensional Iowa Suggestibility Scale (MISS), recently developed by Kotov, R.I. et al, is a self-reporting questionnaire that attempts to get at various dimensions of suggestibility. The questionnaire can be found at the following URL:

http://www.stonybrookmedicalcenter.org/system/files/MISS_FINAL_BLANK_0.pdf

The results from this questionnaire might be biased for individuals who have read this post and who would prefer to convince themselves or a clinician that they are not suggestible.