Lessebo effect: what it is and how it affects research

In clinical trials with a randomized control group, it is appropriate to measure to what extent the The belief of receiving the experimental treatment influences the degree of improvement reported by the volunteers.

The placebo effect is widely known in research, which can be defined as the improvement perceived by the participants, who believe they have received the effective treatment, despite not being so.

However, the placebo effect is not the only one that can occur in this type of trial. The lessebo effect, along with the nocebo, are also the product of suggestion.. Next we will see what the lessebo effect is, in addition to relating it to the other two.

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The lessebo effect and relationship with research

In science, when a new clinical intervention is created, be it a drug, a new type of therapy or any new treatment, it is necessary, first of all, to check if it really works. For this, it is common for clinical trials to be carried out, in which participants volunteers who have the medical or psychiatric condition that the new intervention is believed to improvement.

However, in order to correctly detect the therapeutic capacity of the new intervention, it is normal for these trials to have, at least, two groups: one experimental and one control. The experimental group will be made up of participants who will receive the intervention, with the intention to see what effects this has on your health, whether there is improvement or worsening of the symptoms. On the other hand, the participants of the control group will not be given any therapeutic treatment. Both the participants of the control group and those of the experimental group do not know which group has touched them.

The objective of forming these two groups is to know to what extent the improvement (and also worsening) of the participants is attributable to the application of the intervention.

The idea is that if there is improvement in the experimental group and not in the control, the improvement is attributable to the treatment. If there is some type of improvement in both groups, it will not be related to the intervention, but rather attributable to the actual course of the medical or psychiatric condition that is intended to be treated. Indeed, there are medical illnesses and mental disorders that can simply improve with the passage of time.

Let's start at the beginning: the placebo effect

So far everything makes sense, but surely a question comes to mind: If the experimental group receives the treatment to be tested, what does the control group receive? The volunteers in the control group have to receive something, otherwise they will know that they are in that group and it is something we do not want. What is wanted in research is to verify the pure and hard effectiveness of the treatment, and for this we need those who are receiving it not to know that they are receiving it but to show improvement if it is cash.

For this reason all participants in the experiment receive something. If the experimental group is given the experimental treatment, the control is given a placebo. A placebo substance or treatment is any intervention that those who apply it know or assume that It does not have any type of effect, neither therapeutic nor harmful. For example, in pharmaceutical research, if the experimental group is given the drug that is believed to work, the control you are going to be given something that looks like a drug, in the form of a pill or syrup, but with no active ingredient some.

And this is where we have to talk about the placebo effect. It is essential that this effect be taken into account in research, since it can perfectly call into question the effectiveness of the new intervention. The placebo effect occurs when the control group, despite not receiving the experimental treatment, reports improvement. The participants who form the control group have the expectation of having received the treatment experimental, and they believe that it is being applied to them, perceiving an improvement that is nothing more than suggestion.

It is important to understand that prior to participating in an experiment, participants are given informed consent. It explains that the experimental treatment being tested may have both benefits as unwanted health effects, and that the aim of the experiment is to find out which are. In addition, they are told that they may receive this treatment or they may be given a placebo. Despite knowing this information, it is not strange that the participants wish to be part of the experimental group, and believe that they have been touched by that group, feeling a supposed improvement.

The use of placebo is the norm in randomized controlled trials.. The logic behind the application of placebos derives from the need to distinguish between the real benefit observed by the participant and the benefit that is the product of their desire to improve. The mind is very powerful and is capable of deceiving us, covering up symptoms and making us believe that we have improved.

Despite the fact that the placebo effect has been known for quite some time and research, both medical, pharmaceutical, psychological and psychiatric institutions have had this in doubt, the existence of two other effects given in an experimental context has been raised: the nocebo effect and the lessebo effect. Both effects are very important, like the same placebo effect, and in fact can bias the interpretation of the results of the experiment.

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The nocebo effect

Before talking more in depth about the lessebo effect, it is convenient to understand, briefly, what the nocebo effect. "Nocebo" comes from the Latin, meaning "I must do harm", in contrast to the term "placebo", which is "I must pleasure". Knowledge of the nocebo effect is considered quite revealing about how it should be applied and interpret everything related to the placebo (ineffective intervention) and its homonymous effect, since even what should have no effect can do harm.

As we have already commented, the placebo effect is, essentially, the improvement perceived by the control group participants despite the fact that they have not been administered anything known to have any effect. The nocebo effect would be the opposite: it is the worsening of the symptoms or signs of a health condition due to the expectation, conscious or not, of undesirable effects of an intervention.

In experimentation there is always an informed consent and, as we have previously commented, in it it is explained that the intervention can have positive and negative effects. If the placebo effect is to believe that the intervention is received and the positive effects are experienced, in the case of the nocebo is also believing that this intervention is being received, but that its effects are manifesting adverse. The participant has pessimistic expectations that make him believe that the treatment is harmful to him.

What characterizes the lessebo effect?

For a long time, research was only concerned with monitoring the suggestion and expectations of the control group, both positive and negative. Under the logic that something necessarily has to happen in the experimental group, both a therapeutic effect and adverse effects, the effects of suggestion were not monitored in that same group. Fortunately, although relatively recently, more attention has begun to be paid to how pessimistic expectations in the experimental group may nullify the real therapeutic effects of the intervention.

If the placebo is the perceived improvement in the control group and the nocebo the worsening, the lessebo effect is the perception of less improvement, cancellation of the effects or worsening in the experimental group. That is, the participants of the experimental group, who are receiving the treatment, believe that they have been given or either a placebo or are suffering from the adverse effects of the treatment, believing that their condition is being worsened.

This it can be due to multiple causes. It may be that, as would happen with the nocebo effect, the participants have a pessimistic view of the effects of the experimental treatment, thinking that they are more likely to suffer its unwanted effects before the therapeutic. Another thing that has been seen is that there are not a few participants who, despite reading the informed consent, do not understand it, and think that "placebo" is synonymous with "harmful". They think that experimental treatment is beneficial and that control is necessarily bad.

scientific implications

It becomes clear that both the placebo and nocebo effects affect research if they are not taken into account, but the effects of lessebo are even worse. As we have commented, it may be that the participant who is receiving an effective treatment think that either it is not or that it is a placebo, and autosuggestion to think that it is not improving or, even gets worse.

Discarding something that, objectively speaking, is working but that volunteers report as harmful due to their pessimistic expectations not only implies discarding a treatment that works, but also implies a loss of resources economic and time. Whether it is a drug, a new psychological therapy or any other type of treatment, its design and application implies the mobilization of many efforts, and that it is discarded due to biases of the experimental participants is a true mistake.

It is for this reason that, based on new research focused on studying the lessebo effect it should be considered how trustworthy the participant is, in the sense of what kind of expectations you have about the experiment and whether it presents an unrealistic style of thinking. Whether you tend toward pessimism or optimism, you need to know this pattern of thinking. thought, and find out to what extent that participant is not going to bias the results of the experiment.

Bibliographic references:

• Master, T. TO. (2020) Nocebo and lessebo effects. International Review of Neurobiology 153, 121-146.
• Master, T. A., Shah, P., Marras, C., Tomlinson, G., & Lang, A. AND. (2014). Another face of placebo: the lessebo effect in Parkinson disease: meta-analyses. Neurology, 82(16), 1402–1409. https://doi.org/10.1212/WNL.0000000000000340