If television advertising is ever effective, many people will receive these genetic tests at Christmas. These tests often allow people to research their inherited trends in health issues, and in some cases lifestyle changes can be proposed to avert future problems ̵
However, DNA test results can also cause problems that would not be there otherwise. Genetic information can exert a strong placebo effect – or the opposite of the nocebo effect. If you think something can hurt you, it is indeed the case. The effectiveness of this effect has not been studied so far.
Some Stanford psychologists wondered if percepting the genetic risk could actually increase a person's risk, regardless of their actual genetic risk. In other words, could you just learn that you have a genetic predisposition to something that produces physiological changes that resemble a tendency to that affinity, regardless of whether you have it? To figure this out, the team designed experiments.
First, they recruited a few hundred volunteers for a "personal health study" in which participants were told they had created genetic profiles and then learned which exercises and diets were best for them. The researchers received a sample of participants' DNA to find their true genetic status for two easily measurable physiological parameters: how much they could walk on a treadmill or how full they were after eating a meal. However, they did not share the results with the participants. The researchers measured this parameter by feeding the participants or putting them on a treadmill to deliver a basic reading.
One week later the same participants were invited again. At the time, researchers lied to half of people about their genetic risk while telling the controls the truth. They let both groups run on the treadmill or eat the same meal again. Then they explained to the participants the truth about the genetic results.
If lying about genetic testing sounds ethically … questionable, the researchers know. They treated their reservations in various ways. First, researchers focused on genetic risk information for obesity; They thought that learning a risk would obviously be a shit, but it's not as if they were telling people that they were at risk for cancer or Alzheimer's. Second, they allowed participants to hold the wrong idea of their genes for just one hour, just long enough for researchers to study the impact of misinformation on behavior and physiology.
Finally, the team notes that "the potentially iatrogenic [induced inadvertently by medical care] effects on learning genetic risk are already being observed on a large scale." Every 25th American adult has already acquired personalized genetic test results, and we might as well investigate how this information affects them.
Nutrition and Fitness
The first sequenced genetic variant was one associated with reduced exercise capacity, with respondents reporting that they had the high-risk genotype, regardless of they did – were faster off the treadmill and did not breathe as efficiently as they did last week before receiving their DNA test results, respondents said they had the protection option run longer before they felt hot or the training was hard , compared to the baseline training of the previous week.
To see if these results are The researchers conducted a similar experiment with a gene of risk factor for obesity. In this experiment, respondents said they had the protective phenotype (whether or not they actually did) after eating the same meal they fed last week, as determined by increased signal molecules in the gut. In this case, the effect of the perceived genetic risk was "much greater" than the actual protective genotype. The effects of the perceived genotype did not differ according to which DNA sequence the participants actually had.
The psychologists who conducted this study are not sure why they found what they are doing. While genetic information can alter behavior, they can not take into account the rapid physiological changes that they have seen here. Stress also does not explain it because the perception of a protective genotype caused a physiological increase in the hormones that control our food. They conclude that the causal mechanism, which seems quite instantaneous, is "mindset."
The results of this ethically challenging study will only lead to ethically more challenging situations. Society is already struggling to decide who should receive information about the genetic risk, including for Parkinson's and Huntington's Diseases, as well as other hereditary diseases for which there is no known cure or treatment. In the meantime, people are receiving information about more subtle genetic influences anyway.
If this information can affect health, as suggested in this study, should physicians ask patients if they know their genetic risk profiles, much as they take patients for pills they ask? And if mere knowledge of the risk itself poses a risk – if that knowledge becomes an additional risk factor affecting health – could doctors withhold this knowledge from patients? Should you?
Nature Human Behavior 2018. DOI: 10.1038 / s41562-018-0483-4 (About DOIs).