The Placebo Effect: A Brief Review

The placebo effect is a most curious phenomenon, which has been known since ancient times. After World War II, it became an important methodological tool in the conduction of clinical trials. The so-called "placebo-reactors" show special sensitivity to these inert substances. In general, 35.5 plus minus 2.2% of patients affected by various conditions proved to react positively to placebos. Several aspects of placebos seem to play a relevant potentiating action on such effects. In this context, surgical rather than clinical seems to be a more efficient placebo. Despite a clearcut role of the limbic system, emphasis has been placed on psychological aspects of the possible pathophysiologic mechanisms.