Suzana Herculano-Houzel


Every time a new drug is tested, it has to be determined whether the substance is inherently active, capable of acting on the body in the desired way – as an anti-inflammatory, antidepressant or antihistamine, for example. As a rule, the effects of the substance are first tested on cells grown in the laboratory, and compared to the effects of other substances known to be innocuous, such as a saline solution or flour. On cultured cells, the effect of these control substances is in fact none – an excellent benchmark for whether the test drug works.

However, when you move on to the next phase and repeat the test with people, surprise: too many times, pills of the inert substance – the placebo – have the desired effect. This is the placebo effect: an improvement similar to that provided by therapies, but which occurs in the absence of an intrinsically therapeutic intervention. If the medicine isn’t real, the effect shouldn’t be either.

And so the placebo effect was criticized as a mere suggestion, a false belief on the part of the patient, who would believe themselves to be better without having actually improved – and therefore a hindrance to medicine, because it made drugs seem ineffective. After all, how can you believe in a treatment when inert substances also have an effect?

It was at the end of the 1990s that the placebo effect ceased to be considered a hindrance or mere suggestion and gained the status of a treatment in its own right, worthy of scientific research into its mechanisms, because the improvement it provides is real – even though it is in fact the result of suggestion. The placebo effect depends on the psychosocial simulation of a therapy, which has biological effects on the brain: in the expectation of feeling better, it already causes changes in its internal analgesia, motivation and stress response control systems.

That’s why flour in everyday food has no therapeutic effect, but a little pill taken as “medicine” can eliminate pain, boost immune function and even mess with your hormones. By increasing the release of dopamine and opium-like substances produced by itself, the brain eases your pain, increases your motivation and improves your overall sense of well-being. Even if it doesn’t cure tumors, serious infections and so many other illnesses outside of its remit, the placebo effect is your brain’s way of helping itself – including going to get more help.

Originally published in Folha de São Paulo in October 2007

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