"Genetic" placebo and nocebo
It doesn't matter what's inside – it matters what you think about it
Maria Perepechaeva, "First-hand Science"
Today we know that the risk of developing many pathologies is largely due to a unique combination of gene variants that we inherited at birth, although factors of a non-genetic nature play a major role in this.
Genetic testing has become firmly established in medical practice as part of an actively developing area – personalized medicine. Based on the results of gene diagnostics, recommendations are given regarding lifestyle, one or another treatment is prescribed.
But the stick turned out to have two ends: psychologists have found that sometimes the very knowledge of a person about the presence of a certain gene variant can serve as a trigger for the practical implementation of this hereditary information.
Scientists from Stanford University (USA), under the pretext of research in the framework of the development of personalized medicine, conducted two unusual experiments in which over two hundred volunteers participated. Article by Turnwald et al. Learning one's genetic risk changes physiology independent of actual genetic risk is published in the journal Nature Human Behavior.
(The Stanford researchers press release found that receiving genetic information can alter a person's risk can be read on the university's website – VM.)
The participants were promised that after the end of the tests they would receive recommendations on nutrition and physical activity, taking into account their genetic profile.
In one experiment, the subjects were determined to have two variants of the CREB1 gene, one of which is associated with increased physical endurance, and the other, on the contrary, with high fatigue. Before and after the announcement of the test results, the participants in the experiment had to run on a treadmill. At the same time, they were randomly divided into two groups, regardless of the actual results of genotyping. The first group was told that they had a "weak" version of CREB1, the second that they had a "strong" one.
After that, the participants of the first group showed the worst results in running, regardless of their real genetic constitution. Moreover, their lung capacity decreased and their ability to remove carbon dioxide from the body worsened. But the participants of the second group showed some increase in endurance, also regardless of which variant of the CREB1 gene they carried.
The second experiment was conducted similarly, only in this case different variants of the FTO gene were analyzed, one of which is associated with a disposition to develop obesity as a result of overeating. At the same time, the subjects were fed a certain amount of food, then offering to assess the degree of saturation.
The results were also similar. Those who were sure that they were carriers of the version of the FTO gene that allows them to quickly get enough, rated the degree of their saturation higher, and their blood actually showed a higher level of the physiological marker of satiety – glucagon-like peptide-1. All participants of the other group felt as usual after the second meal.
Thus, an amazing thing was discovered: the very knowledge of the presence of certain gene variants in a person can affect not only human behavior, but even physiological parameters! This effect is similar to the effects of placebo and nocebo – drugs that do not have real pharmacological activity, but have a positive or negative effect on the patient.
Do these results mean that it is not worth "once again" to be tested, for example, for gene variants associated with the risk of cancer? As is known, placebo can change the functioning of the cardiovascular, endocrine, immune and nervous systems, and if tumor growth is not associated with the work of these systems, then it is unlikely to be affected by the effect of a "genetic placebo".
However, older people who were informed that they had a genetic variant that increased the risk of developing Alzheimer's disease began to cope worse with memory tests.
Thus, specialists face another ethical problem: should they tell the patient about the results of his genetic examination, if this knowledge can harm him? It is not easy to solve it. To do this, you need to know not only how the risks of developing pathologies change after informing people about the results of gene diagnostics, but also how information obtained from other sources affects. For example, if we know that this or that disease was in our relatives, or that it should be a consequence of our unhealthy lifestyle.
In general, the results of these experiments confirmed the popular statement that thought is material. So let's think well, and first of all – about ourselves!
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