History

Ancient Greek medicine and the humoral medicine of the Middle Ages and Renaissance simply took for granted that words had the power to both cause or cure disease and that the mind and the body were constantly interacting to determine the individual's state of health. The earliest known reference to deliberate use of a placebo appears in a 1580 essay by Montaigne (1533 – 1592) describing a hypochondriac who was cured by an enema administered with great fanfare but without any substance actually being injected into the body. It is almost certain, however, that the use of placebos in medicine antedates this essay, probably by many centuries.

Medical science underwent a more materialistic turn and began to ignore the mind during the nineteenth century, but even then, citations appeared in the medical literature testifying to the power of placebos, and to the imagination generally, to alter disease. Placebos were frequently administered in the nineteenth century, in part because the profession lacked more effective medicines for most diseases.

Benjamin Franklin (1706 – 1790) was one of the first to use a single-blind technique in experiments on the power of mesmerism (hypnosis) conducted in 1785. Franklin was able to show by concealing the hypnotist behind a curtain that subjects' reactions were based on what they thought was happening and not on what was actually happening. Medicine increasingly demanded a blind technique when investigating "unconventional" or "quack" remedies in the nineteenth century but resisted the idea that conventional medical drugs and other remedies ought to be subjected to the same methods. After World War II. medical scientists became more aware of the potential for bias to skew research results if either the subject of the experiment, or the physician observing the experiment, knew who was receiving the "true" medicine, so the double-blind design, with neither party knowing which subject got the study medication and which got the placebo, gradually was adopted as the standard of valid research. Thus, precisely when placebos were less often used in medical practice (because so many powerful new drugs were available), placebos began to be used much more often as a research tool.

Modern medical ethics demands frank disclosure to the patient of the nature of any treatment administered. This, in most cases, rules out the deceptive use of placebos in therapy. But ethics does not rule out the attempt to elicit a placebo effect by creating a positive emotional environment during interaction with the patient. After largely dismissing the mind for many decades as largely unimportant and resistant to scientific study, modern medical science has developed a renewed interest in understanding the mechanisms by which the placebo effect might work. In 2001, the U. S. National Institutes of Health announced a new research program specifically aimed at understanding the mechanisms of the placebo effect and helping practicing physicians to enhance the effect.