Placebo

Abstract

From the Latin “I shall please”, placebo entered ecclesiastical English in the 13th century, but did not appear in medical parlance until the late 18th century. Hooper's Medical Dictionary of 1811 defined the term as “any medicine adapted more to please than benefit the patient”.In the 19th century, as some practitioners became sceptical about the value of much of their existing armamentarium, the deliberate prescription of a pharmacologically ineffective preparation became commonplace. Some placebos were bread or starch pills, others were pharmacologically active drugs prescribed in subtherapeutic doses or to treat a condition for which they were considered ineffective. Physicians thought that placebos would exert no physiological or therapeutic effect whatsoever, other than satisfying the patient's desire for treatment. This understanding of “placebo” also encompassed non-drug therapies, such as Mesmerism, and often had connotations of shady practice. Physicians were reluctant to admit to administering placebos, and many used the term pejoratively to describe treatment offered by rivals or by those whom they regarded as quacks. By the early 20th century, “placebo” increasingly referred to inactive medication rather than non-drug treatments or subtherapeutic dosing.Towards the end of the 19th century, investigators studying psychic and psychological phenomena came across problems—deliberate fraud, the “power of suggestion”—which they attempted to overcome with blinding and placebos. This culminated in the advent of randomised controlled trials (RCT) in the mid-20th century, when a placebo-treated control group became a mainstay of therapeutic investigation. An RCT that compares a new therapy with a placebo rather than no treatment, implicitly assumes that the placebo itself exerts an effect. This underlined a fundamental change in our understanding of the placebo, from an inactive therapy issued simply to placate a patient, to a pharmacologically inert but psychologically and physiologically active preparation. This placebo effect became the subject of investigation for some three decades from the 1950s, and strong claims were made for its physical and psychological influences. But at the same time the use of placebos in therapy was increasingly abandoned as paternalistic and dishonest. The placebo had been redefined from a therapeutic device to a tool for proper therapeutic evaluation. From the Latin “I shall please”, placebo entered ecclesiastical English in the 13th century, but did not appear in medical parlance until the late 18th century. Hooper's Medical Dictionary of 1811 defined the term as “any medicine adapted more to please than benefit the patient”. In the 19th century, as some practitioners became sceptical about the value of much of their existing armamentarium, the deliberate prescription of a pharmacologically ineffective preparation became commonplace. Some placebos were bread or starch pills, others were pharmacologically active drugs prescribed in subtherapeutic doses or to treat a condition for which they were considered ineffective. Physicians thought that placebos would exert no physiological or therapeutic effect whatsoever, other than satisfying the patient's desire for treatment. This understanding of “placebo” also encompassed non-drug therapies, such as Mesmerism, and often had connotations of shady practice. Physicians were reluctant to admit to administering placebos, and many used the term pejoratively to describe treatment offered by rivals or by those whom they regarded as quacks. By the early 20th century, “placebo” increasingly referred to inactive medication rather than non-drug treatments or subtherapeutic dosing. Towards the end of the 19th century, investigators studying psychic and psychological phenomena came across problems—deliberate fraud, the “power of suggestion”—which they attempted to overcome with blinding and placebos. This culminated in the advent of randomised controlled trials (RCT) in the mid-20th century, when a placebo-treated control group became a mainstay of therapeutic investigation. An RCT that compares a new therapy with a placebo rather than no treatment, implicitly assumes that the placebo itself exerts an effect. This underlined a fundamental change in our understanding of the placebo, from an inactive therapy issued simply to placate a patient, to a pharmacologically inert but psychologically and physiologically active preparation. This placebo effect became the subject of investigation for some three decades from the 1950s, and strong claims were made for its physical and psychological influences. But at the same time the use of placebos in therapy was increasingly abandoned as paternalistic and dishonest. The placebo had been redefined from a therapeutic device to a tool for proper therapeutic evaluation.