[The relationship between the placebo effect and spontaneous improvement in research on antidepressants. Are placebos powerless?].

Clinical trials of antidepressant medications have generally found large changes in groups given a placebo, which may be due to either spontaneous remission or a true placebo effect. This paper reviews the evidence for a true placebo effect in the treatment of unipolar depressed outpatients. Although there is no evidence from experimental studies, a rather substantial amount of circumstantial evidence indicates a true placebo effect. This article raises the question of whether it is meaningful to require experimental evidence for a loose and unspecified concept involving varying components such as placebo.