The nocebo effect: what is it and how does it affect people?

The nocebo effect causes symptoms of discomfort caused in part by expectations.

The placebo effect is a scientific concept of enormous popularity that, perhaps because it is a tremendously curious phenomenon, has become part of colloquial language. For this reason, many people have a rough idea of what it is and what its scope is.

Placebo describes a positive effect on the organism following the use of a substance whose chemical properties are actually harmless, having become known in particular for its presentation as sugar tablets "disguised" as a real medicine.

Accumulating evidence suggests that the following may play a fundamental role in this effect the person's beliefs and expectations. In this sense, it is understood that the benefit is associated with internal variables whose analysis is essential to understand the individual response to the use of any drug or therapeutic procedure (regardless of its objective impact on the body).

Like many other things in the sciences, there is also an antagonist for the placebo effect: the nocebo effect. This article will deal precisely with it, highlighting the nature of a less known but equally interesting reality.

The nocebo effect

The term nocebo comes from Latin. Its form resorts to a verbal declension in the future for the verb "nocere", and its literal translation could be "(I) will do harm". It is therefore the opposite of the placebo phenomenon. This nocebo effect refers to any harm that may occur following the consumption of a substance that in reality lacks "properties" to explain it, and hypotheses must be used in which the contribution of subjective aspects is considered. Such impairments are often referred to as "harmful", "undesirable" or even "dangerous".

Their description was much later than that of placebo, the original references being found in texts from the 1970s, although their definitive conceptual delimitation would have to wait until the early 1980s. The pioneering experiments on the subject made use of fictitious electric currents to induce supposed "headaches.. In this case, the researchers deliberately provided false information to the subjects, making them believe that they would feel such a symptom after its application. Although no shock was ever administered, almost all participants reported suffering from headache (to some degree) after the trial.

Theoretical models to explain it resort to the role of expectations, as in the case of placebo, but also to classical conditioning and personality variables. The truth is that discovering its nature is important, because it can sometimes hinder the way in which a person adheres to pharmacological treatments that could lead to a clear improvement in his or her state of health. For this reason, numerous research projects have been carried out over the last decade to better understand it.

In general, we know that up to 19% of people report negative side effects from using a substance whose chemistry cannot explain them in any way. in any way. These are sometimes legal drugs, for which no consequences or harm have been described in the direction indicated, but which the person expressly perceives (sometimes due to past experiences or incorrect "ideas" about how they work in the body). The effect is more common among women (30%) than men (19%).

Why does it occur?

The exact mechanisms by which the nocebo effect concurs are still largely unknown.The exact mechanisms by which the nocebo effect occurs are still largely unknown, because its study often involves some kind of ethical or moral dilemma. This is so because it would involve lying to the subject about what is administered to him, and specifically making him believe that he is going to voluntarily expose himself to a dangerous or harmful experimental condition. Since it is necessary for the person to believe in this effect, it would imply the acceptance of self-injurious conditions that escape the deontological codes of research activity.

Nevertheless, at least four variables involved in the appearance of the nocebo effect are known today: personal expectations, classical conditioning, personality dimensions and life experience. In this section we will delve into all of them.

1. Expectation

The value of expectations is essential for the nocebo effect, so that what the subject expects to experience ends up imposing itself in reality as a tangible result on his organs and tissues. It is for this reason that in the study of this phenomenon, it is essential to provide the person with information on the "symptom" that one wishes to elicitThis being false (in the sense that the substance or procedure lacks any effect on his body), but used with an explicit intention to convince the subject of the contrary. It has been contrasted, in particular, with algic responses (pain).

With this, and especially by resorting to an authority figure (the researcher), a solid expectation would be formed with the power to generate the suggested negative effects. For example, it is known that beliefs about the emetic effect of chemotherapy (ability to provoke nausea or vomiting) are proportionally related to the occurrence of this unpleasant secondarily.

2. Classical conditioning

Classical conditioning has received much credit as one of the procedures on which the possible development of a nocebo effect is based. In this particular case, it would be an association (by contingency and repetition) of an unconditioned stimulus and a neutral stimulus, the first of which has the capacity to provoke a response in the organism (innate). Thus, through repetitive exposure to situations in which both are presented at the same time, the originally neutral stimulus would acquire the property of a conditioned stimulus.. This means that it would go on to generate effects similar to those elicited by the original unconditioned stimulus.

A simple example of this type of nocebo was found in a study in which a group of people were offered a lemon-flavored drink at the same time they received a dose of chemotherapy.

The repeated presentation of this sequence finally caused the lemon soda (neutral stimulus) to be associated with the side effect (nausea) of such treatment (unconditioned stimulus), so that its isolated consumption would produce the vomiting response. That is, the lemon would generate this unpleasant sensation in the absence of the treatment, thus becoming a conditioned stimulus. This process would therefore produce a nocebo effect for innocuous beverages.

3. Personality factors

It is known that certain personality traits can contribute substantially to the development of the nocebo effect. They would be, therefore, tacit elements of mediation between what was previously described (expectation and classical conditioning) and its occurrence. With regard to these dimensions, it is now known that pessimists (i.e., people who recurrently draw up gloomy expectations) are more likely to suffer from the nocebo effect. Similarly, and perhaps as a direct consequence, they do not refer to the placebo and its benefits in an equivalent way to those who are optimistic (but much less so).

Likewise, type A personality (which alludes to a recurrent sense of urgency and competitiveness as an elementary variable in interpersonal relationships) is also associated with a higher risk of the nocebo effect, when compared to type B (much more "balanced" in time management and social life). The same can be said with respect to neuroticism (tendency to worry and experience negative emotions). Thus, it is concluded that pessimism, neuroticism and attitudes that emphasize competitiveness are important for understanding the phenomenon.

4. Personal experiences

Finally, a fourth explanatory factor is found in previous life experiences. Having witnessed someone suffering the adverse effects of a drug, or building the anticipation that they will occur after acquiring inaccurate knowledge of how they work in the body, is a risk factor associated with learning. All of this can be accentuated on the assumption that the original vicarious modelThe original vicarious model, from which the expectation was articulated, was someone to whom we have an emotional bond.

Adverse experiences with respect to the healthcare system, as a whole, also precipitate the nocebo effect (as they shape the belief that these professionals are incompetent or that they make invalid judgments). If the treatment is carried out during a forced admission, against the explicit will of the person to whom it is administered, the problem is also significantly aggravated. The latter modality is currently the subject of intense controversy, and should only be applied in the case of any suspected potential risk to the person or to third parties.

How can it be approached?

To avoid the appearance of the undesirable nocebo effect, it is essential to influence the variables susceptible to it, such as the person's expectations with respect to the drug or the interaction that occurs in the therapy space. One of the general recommendations is to provide adequate information and to do so in a realistic manner, emphasizing the most appropriate balance possible between the benefits and harms that all drugs have. This is relevant in all intervention contexts, but more so in those that are particularly critical because of the expectations that accompany them (e.g. chemotherapy, where there are many preconceived ideas about its effects).

It is important to provide information as directly and truthfully as possible, promoting that the person can actively participate in the treatment that he/she is going to receiveand that uncertainty about the treatment is minimized as much as possible. In this way, the subject actively collaborates in his or her process towards recovery or improvement, and a quality therapeutic bond is stimulated. This form of relationship has been shown to reduce the risk of the nocebo effect, and is also the way to increase the person's satisfaction with the care received.

In short, the professional's objective should focus on the contextualization of the benefits and side effects of the compound to be used, on the detection and correction of erroneous preconceptions, on the search for active collaboration during the decision-making process, on the appropriate adjustment of expectations, and on building a human contact with the person receiving care. All this will contribute to the reduction of the nocebo effect and a proportional increase in therapeutic adherence.

Bibliographic references:

• Data-Franco, J. and Berk, M. (2012). The nocebo effect: A clinicians guide. The Australian and New Zealand journal of psychiatry, 47(7), 103-118.
• Kong, J. and Benedetti, F. (2014). Placebo and Nocebo Effects: An Introduction to Psychological and Biological Mechanisms. Handbook of experimental pharmacology, 225, 3-15.