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#REDIRECT [[Placebo]]
{{rewrite|3 July 2006}}

{{mergeto|placebo}}



==Placebos in clinical trials==

Placebo simulators are a standard [[Scientific control|control]] component of most [[clinical trial]]s of drug efficacy.

In recent times, the practice of using an additional, [[natural history group]] as the trial's so-called "''third arm''" has emerged; and trials are conducted using three randomly selected,<ref>"David (1949), p.28:
:''it is necessary to remember the adjective ‘random’ [in the term ‘random sample’] should apply to the method of drawing the sample and not to the sample itself.''</ref> equally matched trial groups:<ref>According to Yoshioka (1998), the first-ever [[randomized clinical trial]] was the trial conducted by the [[Medical Research Council]] (1948) into the efficacy of [[streptomycin]] in the treatment of [[pulmonary tuberculosis]].There were two test groups in this trial
:(a) those "''treated by streptomycin and bed-rest''", and
:(b) those "''[treated] by bed-rest alone''" (the control group).
What nmade this trial exceptional was that the subjects were randomly allocated to their test groups. The up-to-that-time practice was to allocate subjects alternately to each group, based on the order in which they presented for treatment. This practice was considered to be biassed, because those admitting the patients knew to which group each patient would be allocated (and it was considered that the admission or non-admission of a specific patient might be influenced by the nature of their illness and the group to which the alternate allocation demanded they would be occupying).</ref>









:1. The '''Active drug''' group ('''A'''): who receive the active test drug.
:2. The '''Placebo drug''' group ('''P'''): who receive a placebo drug that simulates the active drug.
:3. The '''Natural history''' group ('''NH'''): who receive no treatment of any kind (and whose condition, therefore, is allowed to run its ''natural'' course).

The outcomes within each group are observed, and compared with each other, allowing us to measure:
:1. The efficacy of the active drug's '''treatment''': the difference between '''A''' and '''NH''' (i.e., '''A-NH''').
:2. The efficacy of the entire '''treatment process''' alone: the difference between '''P''' and '''NH''' (i.e., '''P-NH''').
:3. The efficacy of the active drug's '''active ingredient''': the difference between '''A''' and '''P''' (i.e., '''A-P''').
:4. The level of the '''placebo response''': the difference between '''P''' and '''NH''' (i.e., '''P-NH''').<ref>Note that, depending upon the focus of your interest, the value of '''P-NH''' can either indicate the ''efficacy of the entire treatment process'' or the ''level of the "placebo response"''.</ref>

The results of these comparisons then determine whether or not a particular drug is considered efficacious.

==Biological substrates of the placebo response==

A "placebo response" can amplify, diminish, nullify, reverse or, even, divert the action of an "active" drug.

Because a "placebo response" is just as significant in the case of an "active" drug as it is in the case of an "inert" dummy drug, the more that we can discover about the mechanisms that produce "placebo responses", the more that we can enhance their effectiveness and convert their potential efficacy into actual relief, healing and cure.

Recent research<ref>For example: Ploghaus, Becerra, Borras & Borsook (2003); Finniss & Benedetti (2005); Benedetti, Mayberg, Wager, Stohler & Zubieta (2005).</ref> strongly indicates that a "placebo response" is a complex psychobiological phenomenon, contingent upon the psychosocial context of the subject, that may be due to a wide range of neurobiological mechanisms (with the specific response mechanism differing from circumstance to circumstance).

The very existence of these "placebo responses" strongly suggest that "''we must broaden our [[concept]]ion of the limits of [[endogenous]] human control''";<ref>Benedetti, Mayberg, Wager, Stohler & Zubieta (2005), p.10390.</ref> and, in recent times, researchers in a number of different areas have demonstrated the presence of biological [[substrate]]s, unique brain processes, and [[neurological]] correlates for the "placebo response":
* 2001: de la Fuente-Fernández and colleagues reported their [[Positron emission tomography|'''PET''']] scan findings on test subjects with [[Parkinson's disease]].
* 2002: Petrovic and colleagues reported their '''PET''' scan findings on test subjects in a trial of [[opioid|opioid analgesia]].
* 2002: Mayberg and colleagues reported their '''PET''' scan findings on test subjects with [[Clinical_depression#Major clinical depression|unipolar depression]].
* 2004: Wager and colleagues reported their '''[[fMRI]]''' scan findings on test subjects in a trial of placebo analgesia.
* 2004: Lieberman and colleagues reported their '''PET''' scan findings on test subjects with [[Irritable bowel syndrome]].
* 2006: Bingel and colleagues reported their '''fMRI''' scan findings on test subjects in a trial of placebo analgesia.
* 2006: Zubieta and colleagues reported their '''PET''' scan findings on test subjects in a trial of placebo analgesia.
* 2006: Sarinopoulos and colleagues reported their '''fMRI''' scan findings on test subjects in a trial neural responses to a highly aversive bitter taste.

A complex fMRI-centred study by McClure, et al. (2004) on the brain responses of subjects who had previously expressed a preference for one or other of two famous, almost identical soft drinks,<ref>That is, [[Pepsi]] and [[Coca-Cola|Coke]].</ref> demonstrated that "[[brand]] information", which "significantly influences subjects’ expressed preferences", is processed in an entirely different brain area from that which is activated in blind taste tests (when their "preferences are determined solely from sensory information").<ref>McClure, Jian, Tomlin, Cypert, Montague & Montague (2004), p.385.</ref> This supports the claim that there are unconscious brain processes that activate the "placebo response".

==See also==
{{col-begin}}
{{col-break}}
* [[Adverse effect (medicine)]]
* [[Autosuggestion]]
* [[Belief]]
* [[Charm]]
* [[Clinical trial]]
* [[Culture-specific syndrome]]
* [[Efficacy]]
* [[Expectation]]
* [[Hypnotic susceptibility]]
* [[Intention]]
* [[E. Morton Jellinek]]
{{col-break}}
* [[Medication]]
* [[Nocebo]]
* [[Observer-expectancy effect]]
* [[Optimism]]
* [[Pessimism]]
* [[Pharmacology]]
* [[Placebo (origins of technical term)]]
* [[Post hoc ergo propter hoc]]
* [[Psychosomatic illness]]
* [[Scientific control]]
* [[Self-fulfilling prophecy]]{{col-break}}
* [[Simulator]]
* [[Stigmata]]
* [[Subject-expectancy effect]]
* [[TGN1412]]
* [[Therapeutic effect]]
* [[Thomas theorem]]
* [[Unintended consequence]]
* [[Uses of the term placebo]]
{{col-end}}

==Notes==
<references/>

==References==

* Benedetti, F., Mayberg, H.S., Wager, T.D., Stohler, C.S. & Zubieta, J., "Neurobiological Mechanisms of the Placebo Effect", ''Journal of Neuroscience'', Vol.25, No.45, (November 2005), pp.10390-10402.
* Bingel, U., Lorenz, J., Schoell, E., E. Schoell, Weiller, C. & Büchel, C., "Mechanisms of Placebo Analgesia: rACC Recruitment of a Subcortical Antinociceptive Network", ''Pain'', Vol.120, Nos.1-2, (January 2006), pp.8-15.
* Colloca, L. & Benedetti, F., "Placebos and Painkillers: Is Mind as Real as Matter?", ''Nature Reviews Neuroscience'', Vol.6, No.7, (July 2005), pp.545-552.
* David, F.N., "Probability Theory for Statistical Methods", ''Cambridge University Press'', (Cambridge), 1949.
* de la Fuente-Fernández, R., Ruth, T.J., Sossi, V., Schulzer, M., Calne, D.B. & Stoessl, A.J., "Expectation and Dopamine Release: Mechanism of the Placebo Effect in Parkinson's Disease", ''Science'', Vol.293, No.5532, (10 August 2001), pp.1164-1166.
* De Pascalis, V., Chiaradia, C. & Carotenuto, E., "The Contribution of Suggestibility and Expectation to Placebo Analgesia Phenomenon in an Experimental Setting", ''Pain'', Vol.96, No.3, (April 2002), pp.393-402.
* Finniss, D.G. & Benedetti, F., "Mechanisms of the Placebo Response and Their Impact on Clinical Trials and Clinical Practice", ''Pain'', Vol.114, Nos.1-2, (March 2005), pp.3-6.
* Lieberman, M.D., Jarcho, J.M., Berman, S., Naliboff, B.D., Suyenobu, B.Y., Mandelkern, M. & Mayer, E.A., "The Neural Correlates of Placebo Effects: A Disruption Account", ''NeuroImage'', Vol.22, No.1, (May 2004), pp.447-455.
* Mayberg, H.S., Silva, J.A., Brannan, S.K., Tekell, J.L., Mahurin, R.K., McGinnis, S. & Jerabek, P.A., "The Functional Neuroanatomy of the Placebo Effect", ''American Journal of Psychiatry'', Vol.159, No.5, (May 2002), pp.728-737.
* McClure, S.M., Jian, L., Tomlin, D., Cypert, K.S., Montague, L.M. & Montague, P.R., "Neural Correlates of Behavioral Preference for Culturally Familiar Drinks", ''Neuron'', Vol.44, No.2, (14 October 2004), pp.379-387.
* Medical Research Council, "Streptomycin Treatment of Pulmonary Tuberculosis: A Medical Research Council Investigation", ''British Medical Journal'', No.4582, (30 October 1948), pp.769-782.
* Petrovic, P., Kalso, E., Petersson, K.M. & Ingvar, M., "Placebo and Opioid Analgesia-Imaging a Shared Neuronal Network", ''Science'', Vol.295, No.5560, (1 March 2002), pp.1737-1740.
* Ploghaus, A., Becerra, L., Borras, C. & Borsook, D., "Neural Circuitry Underlying Pain Modulation: Expectation, Hypnosis, Placebo", ''Trends in Cognitive Sciences'', Vol.7, No.5, (May 2003), pp.197-200.
* Sarinopoulos, I., Dixon, G.E., Short, S.J., Davidson, R.J. & Nitschke, J.B., "Brain Mechanisms of Expectation Associated with Insula and Amygdala Response to Aversive Taste: Implications for Placebo", ''Brain, Behavior, and Immunity'', Vol.20, No.2, (March 2006), pp.120-132.
* Wager, T.D., Rilling, J.K., Smith, E.E, Sokolik, A., Casey, K.L., Davidson, R.J., Kosslyn, S.M., Rose, R.M. & Cohen, J.D., "Placebo-Induced Changes in fMRI in the Anticipation and Experience of Pain", ''Science'', Vol.303, No.5661, (20 February 2004), pp.1162-1167.
* Yoshioka, A., "Use of Randomisation in the Medical Research Council’s Clinical Trial of Streptomycin in Pulmonary Tuberculosis in the 1940s", ''British Medical Journal'', Vol.317, No.7167, (31 October 1998), pp.1220–1223.
* Zubieta, J., Yau, W., Scott, D.J. & Stohler, C.S., "Belief or Need? Accounting for Individual Variations in the Neurochemistry of the Placebo Effect", ''Brain, Behavior, and Immunity'', Vol.20, No.1, (January 2006), pp.15-26.

==Additional references==
* Charcot, J.M., "The Faith-Cure", ''The New Review'', Vol.VIII, (January 1893), pp.18-31.
* Di Blasi, Z., Harkness, E., Edzard, E., Georgiou, A. & Kleijnen, J., "Influence of Context Effects on Health Outcomes: A Systematic Review", ''The Lancet'', Vol.357, No.9258, (10 March 2001), pp.757-762.
* Goddard, H.H., "The Effects of Mind on Body as Evidenced by Faith Cures", ''American Journal of Psychology'', Vol.10, No.3, (April 1899), pp.431-502.
* Hahn, R.A. & Kleinman, A, "Belief as Pathogen, Belief as Medicine: "Voodoo Death" and the "Placebo Phenomenon" in Anthropological Perspective", ''Medical Anthropology Quarterly'', Vol.14, No.4, (August 1983), pp.3, 16-19.
* Houston, W.R., "The Doctor Himself as a Therapeutic Agent", ''Annals of Internal Medicine'', Vol.11, No.8, (February 1938), pp.1416-1425.
* Kirsch, I., "Response Expectancy as a Determinant of Experience and Behavior", ''American Psychologist'', Vol.40, No.11, (November 1985), pp.1189-1202.
* Kirsch, I., "Response Expectancy Theory and Application: A Decennial Review", ''Applied and Preventive Psychology'', Vol.6, No.2, (Spring 1997), pp.69-79.
* Lorenz, J., Hauck, M., Paura, R.C., Nakamura, Y., Zimmermann, R., Bromm, B. & Engela, A.K., "Cortical Correlates of False Expectations During Pain Intensity Judgments — A Possible Manifestation of Placebo/Nocebo Cognitions", ''Brain, Behavior, and Immunity'', Vol.19, No.4, (July 2005), pp.283-295.
* McGlashan, T.H., Evans, F.J. & Orne, M.T., "The Nature of Hypnotic Analgesia and Placebo Response to Experimental Pain", ''Psychosomatic Medicine'', Vol.31, No.3, (May-June 1969), pp.227-246.
* Merton, R.K., "The Unanticipated Consequences of Purposive Social Action", ''American Sociological Review'', Vol.1, No.6, (December 1936), pp.894-904. [http://www.compilerpress.atfreeweb.com/Anno%20Merton%20Unintended.htm]
* Miller, F.G., "William James, Faith, and the Placebo Effect", ''Perspectives in Biology and Medicine'', Vol.48, No.2, (Spring 2005), pp.273-281.
* Miller, F.G., "Sham Surgery: An Ethical Analysis", ''The American Journal of Bioethics'', Vol.3, No.4, (Fall 2003), pp.41-48.
* Perlman, L, "Nonspecific, Unintended, and Serendipitous Effects in Psychotherapy", ''Professional Psychology: Research and Practice'', Vol.32, No.3, (June 2001), pp.283–288.
* Pyysiäinen, I., "Mind and Miracles", ''Zygon'', Vol.37, No.3, (September 2002), pp.729-740.
* Shapiro, A.K., "A Contribution to a History of the Placebo Effect", ''Behavioral Science'', Vol.5, No.2 (April 1960) pp.109-135.
* Shapiro, A.K., "Semantics of the Placebo", ''Psychiatric Quarterly'', Vol.42, No.4, (December 1968), pp.653–695.
* Staats, P., Hekmatb, H. & Staats, A., "Suggestion/Placebo Effects on Pain: Negative as Well as Positive", ''Journal of Pain and Symptom Management'', Vol.15, No.4, (April 1998), pp.235-243.
* Stam, H.J., ''Hypnotic Analgesia and the Placebo Effect: Controlling Ischemic Pain'', (Ph.D. Dissertation), Carleton University, (Ottawa, Canada), 1984.
* Stam, H.J. & Spanos, N., "Hypnotic Analgesia, Placebo Analgesia, and Ischemic Pain: The Effects of Contextual Variables", ''Journal of Abnormal Psychology'', Vol.96, No.4, (November 1987), pp.313–320.
* Stewart-Williams, S. & Podd, J., "The Placebo Effect: Dissolving the Expectancy Versus Conditioning Debate", Psychological Bulletin, Vol.130, No.2, (March 2004), pp.324-340.
* Wilson, I., ''The Bleeding Mind: An Investigation into the Mysterious Phenomenon of Stigmata'', Paladin, (London), 1991.

==External links==

* [http://www.studentbmj.com/issues/02/02/education/12.php What modifies a healing response]

Latest revision as of 10:51, 13 December 2006

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