A new look at the placebo effect
A placebo is a dummy drug (for example, a glucose tablet), the effectiveness of which is due not to its direct effect on the body, but to the patient's belief in its effectiveness. But if such an effect exists (and the placebo effect has been repeatedly proven), why did people not develop the ability to recover without medication at all, not only from a runny nose (which, as you know, passes in a week during treatment, and without pills – in seven days)?
Researchers at the School of Biological Sciences at the University of Bristol have developed mathematical models of the placebo effect, allowing us to analyze the compromise relationship between the load on the body and the benefits of triggering an immune response when such a need arises.
The work is based on the idea expressed by the theoretical psychologist Professor Nicholas Humphrey (Nicholas Humphrey). He suggested that due to the uncertainty of the situation in the surrounding world (for example, the possibility of hunger), the best option for the body may be the work of the immune system "not at full strength". At the same time, any signals indicating the possibility of changes may affect the level of the immune response.
In other words, the constant maintenance of maximum activity of the immune system can deplete the energy reserves of the body, therefore, if the infection is not life-threatening, it is advisable to wait until confirmation that the fight against it itself will not be more bitter than the disease.
This idea was based on animal observations. For example, Siberian hamsters practically do not fight infections if the lighting of their cage corresponds to the winter period: short days and long nights. Changing the lighting mode to summer leads to the launch of a full-fledged immune response in animals.
According to Humphrey's theory, animals subconsciously trigger an immune response as a reaction to a long daylight corresponding to a food-rich summer period. People also subconsciously react to treatment, even fictitious, because they are convinced that it will weaken the infection, allowing the immune system to quickly cope with it without additional energy costs.
The developed models go even further and demonstrate that the placebo effect is modulated by the patient's expectations. Earlier studies, in which brain activity was measured using functional magnetic resonance imaging (FMRI), demonstrated the relationship between the placebo effect and the activity of the regions of the brain responsible for expectations. This pattern is an experimental proof of the validity of theoretical models.
The models show why changes in the perception of the value of recovery and good health or the importance of external factors can induce a placebo effect.
Now that the theoretical approach of the Bristol scientists has laid the foundations for understanding the placebo effect, further empirical work will help to understand how to bring this effect into action and manage it in a clinical setting. The data obtained clearly indicate that in the future, when conducting clinical trials under placebo control, special attention should be paid to the nature of the patient's hopes for treatment, and not just to find out the benefits or uselessness of therapy. A better understanding of the placebo effect can completely change the norms of professional behavior of medical workers and save a huge number of lives.
Article by Pete C. Trimmer et al. Understanding the placebo effect from an evolutionary perspective is published in the journal Evolution and Human Behavior.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of the University of Bristol: New insights into placebo effect.
19.09.2012