Personal genetic information can create a powerful filter that could produce harmful changes in perception and behavior, according to two studies from a research team at Yale University.
People who were told their genes predisposed them to depression reported higher levels of depressive symptoms than people without this knowledge, reported Matthew Lebowitz, PhD, now at Columbia University, and Yale psychology professor Woo-kyoung Ahn, PhD, in the Journal of Consulting and Clinical Psychology. And people who were told they genetically were not predisposed to obesity were much more likely to choose unhealthy foods than people without this information, they wrote in the journal Appetite.
“While potential benefits of making genetic information available seem to be well understood, there may be a downside that needs to be grappled with,” Lebowitz told MedPage Today. “Now is a good time for the field to be thinking about these issues, before personalized genetic testing becomes widespread in more areas of healthcare.”
In both studies, Lebowitz and Ahn used a saliva test disguised as genetic screening. The researchers debriefed all participants after they completed the studies, explaining no actual genetic testing had been conducted.
In the study about depression, they set out to determine whether past experiences of psychiatric symptoms could be distorted by misunderstandings about genetics.
“Mental health disorders are diagnosed on the basis of subjective self-report; we diagnose people based on them telling us what they remember about the symptoms they experienced,” Lebowitz explained. “Anything that could distort or alter people’s memories of their symptoms potentially could interfere with the accuracy of diagnoses.”
Lebowitz and Ahn recruited participants for two experiments in this study through Amazon’s online Mechanical Turk (MTurk) platform, a service that lets individuals complete tasks in exchange for pay. In the first experiment (n=429), participants had an average age of 32.5, and 47.3% had a bachelor’s or postgraduate degree. In the second experiment (n=741), the average was 34.8 and 54.6% of participants held a bachelor’s or postgraduate degree. In both groups, slightly more than half of the participants — about 53% — were female.
The researchers mailed saliva testing kits to participants, leading them to believe the test was a way to gauge genetic susceptibility to depression. They assigned participants randomly to one of several conditions, including:
• Gene-absent, in which participants were told they did not carry a gene predisposing them to depression;
• Gene-present, in which participants were told they did carry the gene; and
• Gene-present/intervention, in which participants were told they carried the gene, but also reviewed an intervention video that explained that genes alone do not deterministically cause major depression and discussed actions people can take to decrease their risk of depression if they are predisposed genetically. In previous work by Lebowitz and Ahn, this video successfully restored feelings of agency over depression, even among people who attributed depression to biological causes.
The researchers asked participants whether they ever had experienced major depression — at least one episode of a low mood that lasted most of the day, almost every day for at least two weeks — and had them complete the Beck Depression Inventory II (BDI-II) to measure depressive symptoms over the past 2 weeks. Possible BDI-II scores ranged from 0 to 60, with higher scores indicating more symptomology.
They found that a larger proportion of patients in both the gene-present and gene-present/intervention groups had greater reporting of having experienced a major depressive episode. Both groups also had significantly higher BDI-II scores than those in the gene-absent group. This suggests that the intervention video didn’t affects respondents’ recall of depression symptoms, the researchers noted.
In the study published in Appetite, the researchers used similar methodology to see what food choices people would make if they thought they were not genetically predisposed to obesity. Participants were asked to pretend they were preordering lunch for a daylong meeting and to select a meal from a list that contained healthy (chicken Caesar salad wrap, salad with grilled chicken, and roasted turkey and avocado sandwich) and unhealthy choices (cheeseburger, meatloaf with mashed potatoes, and baked ziti with three cheeses). The researchers also asked six questions about the importance of diet and exercise on a scale of 1 (not important) to 7 (very important).
This test group was mostly women (60.2%) between 18 and 39 years old (76%). Most considered themselves to be normal weight (45.6%), though 38.9% said they were overweight and 13.7% said they were obese.
After controlling for current weight status, Lebowitz and Ahn saw that 15.7% of the people in the gene-present condition selected an unhealthy option, compared to 28.8% in the gene-absent condition. The only independent variable that emerged as significant was the one representing gene-absent feedback, indicating that this information significantly increased participants’ likelihood of selecting unhealthy choices, not their weight.
The importance of diet and exercise also was significantly lower among people in the gene-absent condition than those in the gene-present condition, they reported.
“Test results we tend to think of as good news can have potentially harmful side effects,” Lebowitz said. “When we told people they didn’t have a genetic predisposition to obesity, they underrated the importance of healthy diet and exercise.”
The findings of both studies have clinical importance, Lebowitz noted. Previous research has shown that the more people attribute their depressive symptoms to genetics and other biological factors, the more pessimistic they are about the future. And in depression and other mental health disorders, he added, subjective experiences may lay the groundwork for future health.
“If subjective experiences are being altered, it could create a negative feedback loop,” Lebowitz explained. “Thinking of yourself as a depressed person can potentially lead to you being more depressed.”
Both studies were limited in that they examined only short-term effects of personalized genetic feedback, since ethically, deception about the saliva test could not be extended. The authors noted that the effects they saw might be more pronounced in disorders that are viewed as more genetically based, and less pronounced in cases in which genes are seen as less determinative.
The studies were funded by the National Institutes of Health. The authors reported no conflicts of interest.
F. Perry Wilson, MD, MSCE Assistant Professor, Section of Nephrology, Yale School of Medicine and Dorothy Caputo, MA, BSN, RN, Nurse Planner