Placebos, placebo effect, and the response to the healing situation: the evolution of a concept

In spite of its impressive progress, medicine has been strongly criticized for relying on its modern biomedical tradition to the neglect of the psychosocial aspects of health. This neglect may account for patients' dissatisfaction and eventual use of alternative health approaches. The concept of placebo has sustained dramatic "protean" metamorphoses through the ages. For centuries, placebos have been regarded as powerful deceptive therapies. From the middle of the twentieth century, however, conventional medicine has used placebos as methodologic tools to distinguish the specific from the nonspecific ingredients in treatments. In modern medical research, the double-blind, placebo-controlled, randomized clinical trial has been established as the gold standard for the assessment of any new treatment. Recently a new trend regarding placebos seems to have emerged. The placebo and other nonspecific effects elicited by the "healing situation" have been independently subjected to scientific study. Progress in this area may promote useful clinical applications, enabling physicians to broaden their perspectives on the healing process. We present the historical changes of the concept of placebo and the ethical issues raised by their use.