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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 - due to the patient being exposed to a purported treatment, and consequently believing that their condition will be improved, irrespective of whether the treatment has any genuine medical benefit. It is usually the suggested mechanism by which alternative medicine appears to work.
For example, sugar pills or saline solutions, which have no pharmacological properties, are commonly prescribed (under altered names) as placebo treatments.
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 would have no effect on patients unfamiliar with or skeptical of the treatment offered.
For example, a homeopathic prescription of water containing a minute dilution of powdered oyster shell may bring some improvement to a patient who has faith in the homeopathic method. While a patient who is skeptical of homeopathy will 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.
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.
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
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). 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, 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.
- The placebo effect may actually be getting stronger over time, as expectations about the power of medicine change.
The placebo effect has a somewhat less well-known, slightly evil cousin; the nocebo effect. 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.
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.
- ↑ Scientific American - Placebo Effect: A Cure in the Mind
- ↑ Analgesic effects of branding in treatment of headaches, A Branthwaite and P Cooper
- ↑ Science Based Medicine - Is There a Placebo Effect for Animals?
- ↑ Behaviorally conditioned immunosuppression, R Ader and N Cohen, Psychosomatic Medicine, Vol 37, Issue 4 333-340
- ↑ Expensive Placebo Works Better Than Cheap One
- ↑ Lucchelli, Cattaneo, Zattoni, Effect of capsule colour and order of administration of hypnotic treatments, European Journal of Clinical Pharmacology, 2004
- ↑ Placebos Are Getting More Effective. Drugmakers Are Desperate to Know Why, Wired Magazine.
- ↑ nocebo effect
- ↑ New Scientist - when mind attacks body
- ↑ Bad Science - All bow before the mighty power of the nocebo effect
- ↑ Adler, Shelley R. Sleep Paralysis. Rutgers: 2011.