The mysterious and powerful effects of placebo

By Marc Gozlan Posted today at 00h17, updated at 15h59

Time to Reading 13 min.

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Placebo? Enigmatic, the word is all the rage, brought up to date by quarrels over the total derogation of homeopathy. It would draw its therapeutic potential from the only placebo effect, a form of self-suggestion related to the taking of small granules, say his critics, while others argue that this placebo effect, relieving some patients and diverting them from more expensive active drugs, well worth taking charge of the community.

The debate will soon be decided by the Minister of Health Agnès Buzyn. It has had the merit of highlighting a mysterious psycho-socio-biological phenomenon, at work in any doctor-patient relationship, but also at the heart of drug evaluation.

If France shines by its absence in the study of the placebo effect, abroad it is a subject of active research that reveals how, in the therapeutic situation, the boundary between body and mind is porous.

But what is the placebo – etymologically, in Latin, "I will please" ? This term is primarily used in clinical research by those who evaluate the actual effectiveness of a drug candidate in a trial. Indeed, most of the time, it is ensured that the molecule of therapeutic interest is more effective than placebo, which is conventionally defined as an inert substance (tablet, liquid, injection) because it lacks any active pharmacological effect. This is called a placebo-controlled clinical trial.

When it is unethical to administer a placebo in subjects with serious pathologies, the drug candidate is evaluated in comparison to a reference drug. This test is said to be comparative. For a pharmaceutical firm, comparing its product to a placebo is more convenient and less commercially risky than comparing it to a competing drug.

Three areas in the gray matter of the brain

In terms of placebo, a clarification is needed from the outset: we could believe that the terms "placebo effect" and "placebo response" are strictly synonymous. It is not so.

"The placebo effect reflects the psychological and neurobiological response, based on the patient's expectations, following the administration of a placebo. The placebo response refers to a positive change in the patient, such as relief from pain, anxiety, nausea. This may be due to the placebo effect, but also to the natural history of the disease or to the Hawthorne effect, which is the change in patient responses simply because they feel 'clinical test and wish to please the investigators ", says Luana Colloca, a professor at the University of Maryland (Baltimore, USA).