”4,5 First used in Western medicine in the

1700s, the term placebo was defined in the 1785 edition of Motherby’s New Medical Dictionary as a “commonplace method or medicine.”6 In 1811, Hooper’s Medical Dictionary defined placebo as “an epithet, given to any medicine adopted to please rather than to benefit the patient.”6 In 1958, the term appeared in the English Psychiatric Dictionary as “a preparation containing no medicine (or no medicine related to the complaint) and administered to cause the patient to believe that he is receiving treatment.”4 Shapiro Inhibitors,research,lifescience,medical suggested that most of the practice of medicine until the 17th century was an exploitation of placebo effects.5,6 Definitions and terminology Shapiro defined a placebo as “any therapy or component of therapy that is deliberately Inhibitors,research,lifescience,medical used for its nonspecific, psychological, or psychophysiological effects, or that is used for its presumed specific effect, but is without specific activity for the condition being treated” and also noted that “specific activity is the therapeutic Inhibitors,research,lifescience,medical selleck compound influence attributable solely to the contents or processes of the therapies rendered [and] should be based on scientifically controlled studies.”6,7 Brody defined placebo as “a form of medical therapy, or an intervention designed to simulate medical therapy,

that at the time of use is believed not to be a specific therapy for Inhibitors,research,lifescience,medical the condition for which it is offered and that is used either for its psychological effect or to eliminate observer bias in an experimental setting; [or is] a form of medical therapy now believed to be inefficacious, though believed efficacious at the time.”8 Placebo effect There is a distinction between a “true placebo effect” versus a “perceived placebo effect.”9 A true placebo effect depends on factors such as the attitudes of the physician and the patient, the suggestibility of the patient, and the type of

treatment.9 A perceived placebo effect results from the influence of such factors as Inhibitors,research,lifescience,medical the natural course of the disease, the tendency of most measures of biological crotamiton variation to regress toward the mean, and unidentified parallel interventions (eg, patients receiving extra attention during a clinical trial, becoming more aware of the problem, and taking actions that influence outcome).9 Placebo response Placebo response represents the apparent improvement in the clinical condition of patients randomly assigned to placebo treatment (eg, a change within the placebo group from pretreatment to posttreatment).10 This change may be due to an effect of placebo, but not necessarily so, as in the case of spontaneous remission.4 Also, a substantial portion of the placebo response (the improvement, that occurs in placebo-treated patients) is a result, of the passage of time and the associated regression to the mean, expected fluctuations in illness course, and spontaneous remission.