In 1955, Henry K. Beecher proposed that placebos could have clinically important effects.[22][23] This view was notably challenged when, in 2001, a systematic review of clinical trials concluded that there was no evidence of clinically important effects, except perhaps in the treatment of pain and continuous subjective outcomes.[23] The article received a flurry of criticism,[24] but the authors later published a Cochrane review with similar conclusions (updated as of 2010).[25] Most studies have attributed the difference from baseline until the end of the trial to a placebo effect, but the reviewers examined studies which had both placebo and untreated groups in order to distinguish the placebo effect from the natural progression of the disease.[23]
Types[edit]
In a 1983 article, Clement J. McDonald, Steven A. Mazzuca, and George P. McCabe, Jr., a placebo as "a substance or procedure... that is objectively without specific activity for the condition being treated".[26] Under this definition, a wide variety of things can be placebos and exhibit a placebo effect. However, the placebo effect may be a component of legitimate pharmacological therapies: Pain-killing and anxiety-reducing drugs that are infused secretly without an individual's knowledge are less effective than when a patient knows they are receiving them. Likewise, the effects of stimulation from implanted electrodes in the brains of those with advanced Parkinson's disease are greater when they are aware they are receiving this stimulation.[27] Sometimes administering or prescribing a placebo merges into fake medicine. Common placebos include pills ("sugar pills") or saline injections. Fake surgeries have also seen some use. An example is the Finish Meniscal Legion Study Group’s trial published in The New England Journal of Medicine, which found a sham meniscal surgery to be equally effective to the actual procedure.[28][29] While examples of placebo treatments can be found, defining the placebo concept remains elusive.[30]
Effects[edit]
The placebo effect has sometimes been defined as a physiological effect caused by the placebo, but Moerman and Jonas have pointed out that this seems illogical, as a placebo is an inert substance that does not directly cause anything. Instead they introduced the term "meaning response" for the meaning that the brain associates with the placebo, which causes a physiological placebo effect. They propose that the placebo, which may be unethical, could be avoided entirely if doctors comfort and encourage their patients' health.[24] Ernst and Resch also attempted to distinguish between the "true" and "perceived" placebo effect, as they argued that some of the effects attributed to the placebo effect could be due to other factors.[31]
Research suggests that for psychological reasons, some placebos are more effective than others. Large pills seem to work better than small pills, colored pills work better than white pills, an injection is more powerful than a pill, and surgery gives a stronger placebo effect than injections do.[32]
Research has also shown when it comes to specific psychological disorders, such as mild or moderate depression, placebos have the same effects compared to antidepressants.[33]
Ethics[edit]
See also: Medical ethics and Philosophy of medicine
The placebo effect has been controversial throughout history. Notable medical organizations have endorsed it,[11] but in 1903 Richard Cabot concluded that it should be avoided because it is deceptive. Newman points out the "placebo paradox" — it may be unethical to use a Placebo, but also unethical "not to use something that heals". He suggests to solve this dilemma by appropriating the meaning response in medicine, that is make use of the placebo effect, as long as the "one administering... is honest, open, and believes in its potential healing power".[20]