Using the placebo response in clinical practice.

This paper reviews the psychological mechanisms that lead to placebo responses and the physiological basis for reduction in symptoms. Some psychological mechanisms (expectancy, conditioning) lead to symptom reduction but are unlikely to reduce underlying pathology. Other mechanisms (therapeutic relationship, empowerment) may additionally reduce later pathology. The nature, size and duration of the placebo response depends on the placebo inducing context. In clinical practice, the placebo response creates an adjunctive response to that of active treatment. It is a useful, but fickle, boon as it is difficult to predict when it will occur.