Methods and Findings in Experimental and Clinical Pharmacology
Vol. 25, Suppl. A, 2003
ISSN 0379-0355
Copyright 2003 Prous Science, S.A.
CCC: 0379-0355/2003
http://www.prous.com

Clinical Trials in Psychiatry: The Placebo Effect

I. Gilaberte

Clinical Research Department , Lilly, Madrid, Spain

The history of medicine is linked to the history of placebo, as this is considered the oldest medical treatment and a powerful ally for the physician. Although it has been considered to be an "inert substance", in psychopharmacological clinical trials in which a control group with placebo is included we find a high placebo response that oscillates between 10 and 60% of cases. The placebo effect has been explained, at least partially, by the natural history of psychiatric disorders, the therapeutic effect caused by the expectation of the patient regarding the treatment and the power of the physician that administers it. In addition, artifacts caused by the current methodology used in clinical trials or the non specific nature of the current psychiatric nosological system can also contribute to a resulting large placebo effect. Nowadays, there is a consensus among Regulatory Authorities (FDA, EMEA) and a great number of investigators agree that placebo is necessary to evaluate the efficacy of new psychiatric drugs, especially on mood disorders. Despite the general acceptance of placebo, its use is not without controversy. Clinical trials that include placebo in the design trouble gaining approval by the Ethical Review Boards and to include patients in the study. For all these reasons, the use of placebo in clinical trials requires a better understanding of the nature and meaning of the response to placebo. However, current efficacy measures in psychopharmacological trials that assess subjective outcomes are not useful. We are beginning to see the results of research focused on the evaluation of physiological indicators for the response to placebo. These brain functional measures may provide more clues on the neurophysiological bases of this phenomenon, helping to distinguish between the effects of placebo and the response to the drug.

Methods and Findings in Experimental and Clinical Pharmacology Vol. 25, Suppl. A, 2003
ISSN 0379-0355 Copyright 2003 Prous Science, S.A. CCC: 0379-0355/2003 http://www.prous.com