PLACEBO

Key words: Placebo, Nocebo, Pain, Disease, Drug

The meaning itself of the word placebo has changed in time: from “drug prescribed to relieve the mind rather than because of its actual effect on the disease” to “improvement observed after the simulated treatment” or to “there is not only one placebo effect but there are many”. However, the “measurable” placebo effect remains a debatable and modest phenomenon. A systematic research of the trials in which patients were administered “placebo” or “no treatment” shows a doubtful result, which is very variable in the different contexts and in the different diseases and which has certain significance only for the effect on pain. Anyhow, the studies of functional neuroimaging show that something happens in the patients treated with placebo. The most consistent observations are those collected on pain, depression and Parkinson’s disease; especially the latter ones highlight protracted clinical effect, accompanied by repeated biological effects at least on two different systems (mesolimbic and striated). The observations on pain underline the activation of the antinocicettive system; it is a “natural” activation reinforced by placebo. The efficacy, repeatedly proven, of breastfeeding or of the administration of sugar to the newborn or suckling child who undergoes a painful procedure is to be referred to this effect. As placebo effect exists, also nocebo effect does; it is due to the wait of a frightening event (undesired effect of a drug). More generally it is possible to say that the context (stress, or vice-versa emotional support), not necessarily mediated by the physician, has significant effects in the evolution of the disease, both in acute phases (major morbidity under stress) and in the chronic diseases (accomplishment and efficacy of the locus of control).