Bronze-level articlePlacebo effect

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==Causes==
 
==Causes==
The placebo effect is quite a complex phenomenon. It is influenced by a multitude of things, including positive thought, reduced stress, the intensity or "drama" of the medical intervention, a patient's expectations of what the treatment can do, and the wider cultural meaning of medical treatment. A particularly interesting observation is how much these factors can be influenced subconsciously; a doctor merely telling someone a treatment will work may not produce such a dramatic effect if the doctor doesn't actually believe it too.  Placebos are not effective on all patients, and may have no effect on patients unfamiliar with or skeptical of the treatment offered.
 
  
For example, a [[homeopathy|homeopathic]] prescription of water containing a minute dilution of powdered [[mollusc|oyster]] shell may bring some improvement to a patient who has faith in the homeopathic method. A patient who is skeptical of homeopathy may experience a reduced effect or no effect at all, as demonstrated by [[James Randi]] when he regularly consumes massive overdoses of homeopathic sleeping pills on stage.
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===Statistical vs indiviudal experience===
  
People's expectations of what drugs and medical treatments can do also change over time. Often the efficacy of real drugs ''decreases'' when a new version is released, as people expect the new one to be better. New treatments, which are perceived to be more effective because they exploit new technologies induce a placebo effect ''in addition to'' their real effect and, sometimes, this can lead to an over-estimate of their real efficacy over an existing treatment. It is also a noted phenomenon that placebo drugs distributed in flashier packaging tend to produce a stronger reaction than their plain packaging counterparts.<ref>[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1505530/ Analgesic effects of branding in treatment of headaches], ''A Branthwaite and P Cooper''</ref>
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The placebo effect is quite a complex phenomenon. It is influenced by a multitude of things, including positive thought, reduced stress, the intensity or "drama" of the medical intervention, a patient's expectations of what the treatment can do, and the wider cultural meaning of medical treatment. A particularly interesting observation is how much these factors can be influenced subconsciously; a doctor merely telling someone a treatment will work may not produce such a dramatic effect if the doctor doesn't actually believe it too. Because of the complexity of issues surrounding what causes a sick patient to get "better", it's difficult to say if an individual was cured by a placebo effect, real treatment, [[regression to the mean]] or a complicated combination of all three. So, the placebo effect is best described as a statistical phenomenon, where prognosis improves for a certain percentage of patients simply exposed to a treatment of some kind.
  
There is also evidence that the placebo effect can work even if the person knows that it is a placebo. This was observed in a study of patients with irritable bowel syndrome.<ref>Kaptchuk TJ, Friedlander E, Kelley JM, Sanchez MN, Kokkotou E, et al. (2010) [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0015591 Placebos without Deception: A Randomized Controlled Trial in Irritable Bowel Syndrome.] PLoS ONE 5(12)</ref> However, the statement issued to patients read "placebo pills made of an inert substance, like sugar pills, that have been shown in clinical studies to produce significant improvement in IBS symptoms through mind-body self-healing processes" - which still creates an ''expectation'' of treatment despite being told there was no chemical reason that such treatment would help. In short, the placebo effect works if you're told the placebo effect works.
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However, as the placebo effect is powered by belief in a treatment and exposure to it it can manifest in individuals to a certain extent. A [[homeopathy|homeopathic]] prescription of water containing a minute dilution of powdered [[mollusc|oyster]] shell may bring some improvement to a patient who has total faith in the homeopathic method. A patient who is skeptical of homeopathy may experience a reduced effect or no effect at all, as demonstrated by [[James Randi]] when he regularly consumes massive overdoses of homeopathic sleeping pills on stage. If these two hypothetical patients begin to feel better anyway, the former would be likely to attribute it to the treatment while the latter would be likely to dismiss it as just feeling better anyway. This leads to [[selective reporting]], and is why [[anecdotal evidence]] shouldn't be trusted over statistical data.
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===Expectation effects===
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Expectations of what drugs and medical treatments can, and do, change over time. Often the efficacy of real drugs ''decreases'' when a new version is released, as people expect the new one to be better. New treatments, which are perceived to be more effective because they exploit new technologies induce a placebo effect ''in addition to'' their real effect and, sometimes, this can lead to an over-estimate of their real efficacy over an existing treatment. This is why in controlled studies of new treatments, they are compared not with inactive placebos but the best effective treatment available (and not least because it is unethical to use placebopathy where a working treatment is known) and the experience between patients is minimised so that they genuinely cannot tell the difference between treatment A and treatment B.
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It is an observed phenomenon that placebo drugs distributed in flashier packaging tend to produce a stronger reaction than their plain packaging counterparts.<ref>[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1505530/ Analgesic effects of branding in treatment of headaches], ''A Branthwaite and P Cooper''</ref> There is also evidence that the placebo effect can work even if the person knows that it is a placebo. This was observed in a study of patients with irritable bowel syndrome.<ref>Kaptchuk TJ, Friedlander E, Kelley JM, Sanchez MN, Kokkotou E, et al. (2010) [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0015591 Placebos without Deception: A Randomized Controlled Trial in Irritable Bowel Syndrome.] PLoS ONE 5(12)</ref> However, the statement issued to patients read "placebo pills made of an inert substance, like sugar pills, that have been shown in clinical studies to produce significant improvement in IBS symptoms through mind-body self-healing processes" - which still creates an ''expectation'' of treatment despite being told there was no chemical reason that such treatment would help.  
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In short, the placebo effect works if you expect the placebo effect to work.
  
 
==Considerations==
 
==Considerations==

Revision as of 10:41, 4 September 2012

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The placebo effect is a psychosomatic phenomenon in which symptoms of a disease or condition lessen - or even appear to be cured completely - from the patient being merely exposed to a treatment. Believing that their condition will be improved, they will begin to feel better and perhaps identifiable symptoms may disappear, irrespective of whether the treatment has any chemical or pharmacological effect. Because of this, controlling for the placebo effect is an essential part of medicine. For example, sugar pills or saline solutions, which have no pharmacological properties, are commonly prescribed as placebo treatments to control for the effect the simple act of intervening in a patient's illness may have.

Most alternative medicine is suggested to work through this method[1] - mostly because any treatment that doesn't work through this method is labelled "medicine". Under placebo control, alternative medicines do not perform significantly better.

Contents

Causes

Statistical vs indiviudal experience

The placebo effect is quite a complex phenomenon. It is influenced by a multitude of things, including positive thought, reduced stress, the intensity or "drama" of the medical intervention, a patient's expectations of what the treatment can do, and the wider cultural meaning of medical treatment. A particularly interesting observation is how much these factors can be influenced subconsciously; a doctor merely telling someone a treatment will work may not produce such a dramatic effect if the doctor doesn't actually believe it too. Because of the complexity of issues surrounding what causes a sick patient to get "better", it's difficult to say if an individual was cured by a placebo effect, real treatment, regression to the mean or a complicated combination of all three. So, the placebo effect is best described as a statistical phenomenon, where prognosis improves for a certain percentage of patients simply exposed to a treatment of some kind.

However, as the placebo effect is powered by belief in a treatment and exposure to it it can manifest in individuals to a certain extent. A homeopathic prescription of water containing a minute dilution of powdered oyster shell may bring some improvement to a patient who has total faith in the homeopathic method. A patient who is skeptical of homeopathy may experience a reduced effect or no effect at all, as demonstrated by James Randi when he regularly consumes massive overdoses of homeopathic sleeping pills on stage. If these two hypothetical patients begin to feel better anyway, the former would be likely to attribute it to the treatment while the latter would be likely to dismiss it as just feeling better anyway. This leads to selective reporting, and is why anecdotal evidence shouldn't be trusted over statistical data.

Expectation effects

Expectations of what drugs and medical treatments can, and do, change over time. Often the efficacy of real drugs decreases when a new version is released, as people expect the new one to be better. New treatments, which are perceived to be more effective because they exploit new technologies induce a placebo effect in addition to their real effect and, sometimes, this can lead to an over-estimate of their real efficacy over an existing treatment. This is why in controlled studies of new treatments, they are compared not with inactive placebos but the best effective treatment available (and not least because it is unethical to use placebopathy where a working treatment is known) and the experience between patients is minimised so that they genuinely cannot tell the difference between treatment A and treatment B.

It is an observed phenomenon that placebo drugs distributed in flashier packaging tend to produce a stronger reaction than their plain packaging counterparts.[2] There is also evidence that the placebo effect can work even if the person knows that it is a placebo. This was observed in a study of patients with irritable bowel syndrome.[3] However, the statement issued to patients read "placebo pills made of an inert substance, like sugar pills, that have been shown in clinical studies to produce significant improvement in IBS symptoms through mind-body self-healing processes" - which still creates an expectation of treatment despite being told there was no chemical reason that such treatment would help.

In short, the placebo effect works if you expect the placebo effect to work.

Considerations

There are a number of ethical issues surrounding the use of placebos, in that they involve medical professions deceiving their patients, not to mention taking full prescription costs for what are essentially worthless products, and sometimes delay the treatment of a real condition due to a doctor mistrusting or underestimating their patient's symptoms. Conversely, they can be an effective treatment for psychosomatic conditions or short-term illnesses, and some have argued that it would be unethical to stop the use of placebos.

The placebo effect can also hinder the scientific method, since the observed effects of a treatment may be greater than the treatment's real medical benefit. This is especially the case with alternative medicine, since the vast majority of patients undergoing alternative treatments are people who believe in their effectiveness, and may experience the same therapeutic effect as a placebo patient. Alternative medicine is often promoted on the basis of personal testimonies from "cured" patients, and other forms of anecdotal evidence, which can often be attributed to the placebo effect, but can be tested objectively by use of double-blind testing (see below).

Use in medical trials

Oscillococcinum, a well-known homeopathic remedy that "works" by the placebo effect.

Because the placebo effect is so powerful, efficacy claims for medical treatments must be tested in an experiment that controls for this effect. This is usually achieved by running a double-blind test, where some patients receive the treatment being examined, and others get a placebo. Neither the patients or the administrators of the treatment know who is in which group. In order for the treatment to be proved useful, it must produce results that are better than the placebo at a statistically significant level. Placebo treatments can often be quite difficult to design, but are still possible. Placebo surgeries have been performed where patients underwent extremely theatrical surgery even though the doctors didn't do much; various operations were done with the patients pretty much being opened up but the surgeons not actually doing anything and patients being given keyhole surgery were dressed up with bandages and post-operation treatment to make it look as though they had conventional operations. Similarly, placebo treatments can be used to test explanations offered by alternative medicine practitioners; a placebo treatment to test acupuncture, for example, would involve sticking the needles into a patient but in more randomised areas rather than the specific places the technique claims are "special".

Quacks who push woo treatments rely on the placebo effect when arguing that their "cures" have an effect. This is exactly why medical tests need to pit a drug against a placebo: anything will usually perform better than nothing. Often, proponents of alternative medicine will reject placebo controlled experiments for any number of excuses, but such trials have been done (very rarely does the alternative medicine world foot the bill for these), and they invariable come up negative.

The strangeness of the placebo effect

The power of the placebo effect produces many strange and interesting quirks. These indicate that the placebo effect may well be more powerful and complex than mere "mind over matter". Many of these examples and their ramifications are discussed in slightly more detail in Ben Goldacre's book Bad Science.

  • The effect has been observed in animals and babies, although in practice this does require conditioning first (which is analogous to just telling someone a treatment will work when you can't communicate more directly).[4][5] This is contrary to claims by homeopaths who claim that their remedies work in babies and animals and can't be due to the placebo effect.
  • Placebos that are "more expensive" work better,[6] as do ones that come in fancier packaging.
  • The effect shows a dose-response relationship like a real medical intervention; two pills are more effective than one.
  • More dramatic placebos are more effective. Injections work better than pills. A full consultation session with a doctor prior to a placebo is more effective than just giving a patient a pill dismissively.
  • The placebo effect can sometimes overpower real pharmacological effects. People who were given very strong drugs to induce nausea didn't develop symptoms as they were told the treatment would actually relieve nausea.
  • There are reports from war zones where saline solutions were used due to shortages of morphine and proved just as effective in battlefield surgery.
  • In one trial, the placebo effect was induced even though the individuals were told that it was a placebo that contains no medicine; although they were told that it was shown to be of help to people with such a condition.
  • As an indication of the wider cultural meaning and subconscious activity of the effect, it is observed that the colour of a sugar pill also affects the placebo response. Certain colours boost the efficacy of placebos for different illnesses, it can even correlate with gender.[7]
  • The placebo effect may actually be getting stronger over time, as expectations about the power of medicine change,[8] but at the same time it can cause drugs that are old to become weaker as the expectation is that new and novel treatments must be better.
  • The placebo effect may be transferable; a patient being around someone who believes that the treatment will work can cause the patient to do better - even if that person is a doctor.[9] This is the reason for double-blinding in drug trials. It may also mean that prayer can affect patients if they know they're being prayed for; rigorous studies of prayer therefore make sure that there is no contact between prayers and patients.

Nocebo effect

The placebo effect has a somewhat less well-known, slightly evil cousin; the nocebo effect.[10][11] This occurs when an individual's expectation of negative effects generate those effects, much like a hypochondriac developing symptoms because he or she is actively watching for something to go wrong with their health. This is particularly important when looking at side-effects of drugs, as a placebo pill can generate the negative side-effects associated with drugs, and in some cases, specific side-effects can be increased by mentioning them prominently or adding an extra layer of suggestion, such as complex consent forms.[12]

For ethical reasons the nocebo effect has not been well studied directly, but it is probably behind the witch doctor's ability to cause illness in those people he curses. It has also been used to explain unusual phenomenon like SUNDS (Sudden Unexpected Nocturnal Death Syndrome) in immigrants from the Hmong people of Laos; belief in angry supernatural forces combined with the phenomenon of sleep paralysis to convince sufferers that they were under attack, leading to extremely high levels of stress which could trigger dormant heart defects.[13]

See also

Footnotes

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