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Placebo - Placebo Effect

What is Placebo?

In modern medicine, the term placebo is used to indicate any medical substance or therapy that is harmless and lacks intrinsic therapeutic activity.

In the above definition, the intrinsic adjective is very important; in fact, placebo can also produce a certain therapeutic effect, but this does not depend on its biological activity. For example, a patient who takes a spoonful of sweetened water believing that it is a cough syrup can obtain - for a sort of self-conditioning - an important therapeutic benefit. In this case, even if the sugary water does not cure the cough in any way, the conviction that it is an effective drug triggers a complex of reactions in the patient that help it heal from the disorder. This suggestive result is called the placebo effect, a term that indicates the curative effect of something that actually has no effect in itself (like drinking a glass of water instead of a medicine, or swallowing a starch pill instead of a drug).

The placebo effect is a much more common phenomenon than one might think; for example, in pathologies with a significant psychosomatic component - such as migraine, insomnia, irritable bowel syndrome, anxiety and headache - the administration of placebo determines an improvement of the pathology up to 80% of cases. The success of placebo in organic diseases is minor, but still important. Even certain fictitious surgical interventions have been shown to produce beneficial effects; therefore the surgery, with its great emotional load, can constitute a powerful placebo and give positive results independent of the surgical act itself.

Pure Placebo and Impure Placebo

  • Pure placebo: substance or form of treatment without intrinsic therapeutic effect;
  • Impure placebo: substance or form of treatment that has an intrinsic therapeutic effect, but not on the specific pathology for which it is prescribed.

Placebo effect: What does it depend on?

The placebo effect is not just a simple psychological response, but a complex biological reaction.

If from the psychological point of view the patient subjected to placebo reacts positively to the therapy, his nervous system releases specific endogenous substances with self-healing properties; among these, the most famous are endorphins, endogenous opioids aimed at mitigating pain, but also various neurotransmitters play an important role in the response to placebo. The immune system itself is strongly influenced by the subject's psychological state, not to mention cortisol and other hormones that are closely dependent on stress levels.

An indispensable requirement for the placebo effect to occur is the self-suggestion (or suggestibility) of the person who takes it; the patient, in other words, must convince himself that he is taking an effective cure and put his trust in it, or at least he must be led to believe it by the doctor who prescribes the cure.

In practical terms, a homeopathic drug tends to work very well in a patient who has a strong sense of ecology, fears the dangers of toxicity of conventional drugs, has a lack of confidence in the health system and condemns the speculation of the big pharmaceutical companies.

Already in the second century after Christ, the Greek doctor Galen had sensed that a doctor heals patients better when they have more confidence in his care.

The placebo response is strongly correlated to the patient's confidence in the treatment that is prescribed for him, which depends largely on the confidence he places in the person who prescribes it . For example, we have seen that the certificates displayed on the walls of the study where the medical consultation takes place increase the efficacy of the placebo.

In addition to these essential requirements, there are numerous factors that contribute to the magnitude of the placebo effect. For example:

  • conditioning (linked to previous experiences → for example knowing that that doctor has healed a friend increases the placebo effect);
  • two capsules are more effective than one;
  • an injectable placebo is more effective than an oral one;
  • the big tablet is more effective than the small one;
  • color of the tablet, for example blue and light green help in case of anxiety, depression and dysphoria;
  • degree of schooling: the most educated and self-sufficient patients, with a high habit of managing responsibilities, were more responsive to placebo;
  • genetic components: according to some studies, the response to placebo would also be strongly influenced by the genetic makeup of an individual, on which the pathways of brain neurotransmitters capable of inducing the placebo effect depend.

Placebo uses

The administration of placebo can have a curative purpose or simply to satisfy, in the patient, the desire to receive a therapy that is actually unnecessary.

In clinical studies, the use of placebo instead aims to verify the real comparative effectiveness of a drug or medical intervention.

Placebo in Clinical Studies

Modern medicine is a medicine based on evidence of evidence, which seeks to demonstrate scientifically - through appropriate experiments - the safety and efficacy of curative treatments, be they pharmacological, instrumental, behavioral, etc.

To take into account the placebo effect, a respectable clinical study foresees that a part of the enrolled subjects is treated with placebo, administered in the same form and in the same ways as the active comparison therapy. For example, if we want to test a drug in tablets, the placebo should be identical in its appearance but without an active ingredient.

Studies that respect this important precaution are called blinded or double-blind controlled clinical trials :

  • Blind : the experiment subjects do not know which treatment (drug or placebo) they are receiving;
  • Double-blind : neither the subjects of the experiment nor the researchers know which treatment is given to each subject.

The aim of blinded studies is to avoid the placebo effect, while the aim of double-blind studies is to guarantee the impartiality of the experimenter in assessing the effects of therapy.

Another important feature of controlled clinical trials is that they are randomized studies, ie that the population is randomly divided into the intended groups (eg those taking the drug, those taking the placebo etc.)

Placebo as Therapy

Until recently, most of the therapeutic effects of medicine were due to the placebo effect.

Consider, for example, the strange concoctions prepared with blood or animal parts, shredded bones, dung, etc., so popular in the Middle Ages.

When we talk about the therapeutic effect of placebo, however, we must not make the mistake of attributing to it any clinical improvement observed in patients taking it. This improvement may depend on numerous other factors; first of all, it has been noticed that many patients tend to turn to the doctor in the most acute phase (when the disorders become more severe) of the disease, which would then tend to improve spontaneously due to its natural course. In addition to cases of spontaneous remission, other elements may lead to incorrect interpretation of the consequences of placebo administration; the patient, for example, can be influenced by independent factors (a new love, a win, a vacation, etc.) that lead him to perceive an improvement in his health, while in other cases he can report the benefits obtained only because he intends to please the doctor.

Placebo effect and Alternative Medicine

The placebo effect may represent the connecting link which, at least partially, agrees with supporters and detractors of the so-called alternative medicines.

All the therapeutic practices whose effectiveness has not undergone controlled or outdated clinical trials belong to the variegated and inhomogeneous group of alternative medicines. The group includes for example naturopathy, chiropractic, ayurveda, yoga, hypnosis, acupuncture, homeopathy and traditional Chinese medicine.

The fact that it is not possible to demonstrate the efficacy of an alternative medicine through the randomized clinical studies mentioned above does not necessarily mean that this is totally useless for the patient.

The placebo effect could therefore explain the positive experiences of doctors and patients who successfully decide to rely (for example) on homeopathic treatments; in this regard, however, we must not forget the other independent factors that contribute to an improvement in the disorder (for example, most people who use homeopathic remedies do so for short-term illnesses; in these cases, it seems that the homeopathic remedy works, but in reality the person would still recover after a few days).

What conventional medicine should learn from alternative medicines is the profound attention they give to the patient's symptoms and his personal and family history. In these disciplines, in fact, a profound relationship is established between doctor and patient, which undoubtedly contributes to determining the terapuetic effect. Therapeutic effect that, even when it is guaranteed by the administration of conventional therapies, can certainly benefit from the additive benefit coming from the placebo effect.

Ethical aspects

The placebo can be deliberately prescribed to a patient with the genuine intent to make him feel better. However, there are circumstances in which the administration of a placebo becomes reprehensible, or at least questionable; for example, when:

  • it takes place in place of conventional therapies that have scientifically demonstrated their clinical efficacy and whose intake would be accepted / tolerated by the patient;
  • slows down the necessary diagnostic investigations;
  • it is too expensive (one might ask why it is expensive to take the same effects with a sugar pill. The answer could be that the patient puts more trust in an expensive product than in a cheap one, but overdo it with the cost of the treatment is in any case condemnable);
  • uses a false placebo (for example when an antibiotic is prescribed for the common cold, exposing the patient to unnecessary side effects and favoring the spread of antibiotic resistance).

Furthermore, it may be questioned whether it is ethically correct to provide a treatment based on deception, since the doctor who relies on placebo cannot inform the patient of the total absence of the active ingredient (on pain of forfeiture of the same placebo effect).

See also: Nocebo Effect »