GenomeWeb – In a randomized controlled trial, people who learned their genetic risk of developing type 2 diabetes did not appear to have increased motivation to make lifestyle changes, University of Cambridge researchers reported.
Some researchers and genetic testing companies have posited that people who learn their genetic risk of disease might be better swayed to make lifestyle changes such as increasing their physical activity. However, that does not appear to be the case, researchers led by Cambridge's Simon Griffin reported in PLOS Medicine today.
Griffin and his colleagues conducted a trial of more than 550 healthy adults in which they randomly assigned the participants to receive their genetic risk estimate for type 2 diabetes, their phenotypic risk estimate for type 2 diabetes, or standard lifestyle advice. As the researchers reported, learning their genetic risk of disease did not influence participants' level of physical activity or self-reported diet and weight. At the same time, the researchers noted no increase in worry or anxiety among participants who were told their genetic risk of disease.
"This is an important observation, given the expectations that such communications might facilitate behavior change and the concerns about the potential adverse psychological consequences of predictive genetic testing," the researchers wrote in their paper.
The researchers invited participants from the population-based observational Fenland Study to take part in their trial. They randomized 569 participants to receive standard lifestyle advice alone or in combination with their genetic or phenotypic diabetes risk estimates. They gauged participants' genetic risk of diabetes using 23 SNPs identified through genome-wide association studies whose links to disease had been replicated in at least one other study, and their phenotypic risk using the Cambridge Diabetes Risk Score.
For both genetic- and phenotypic-based scores, the participants were told their risk of developing diabetes as a percentage and an estimation, such as below average, average, or above average, in comparison with their age and sex-specific group. They were also told what portion of the study sample had a risk estimate that was higher, lower, or equal to their own. This information was also provided visually, the researchers noted.
After eight weeks, the researchers found no differences in physical activity level, as determined by the Actiheart device — which is both an accelerometer and heart rate monitor — the participants wore, between the groups that received genetic risk information, phenotypic risk information, or only standard lifestyle advice.
When they broke the groups down further by age, and whether subjects received a high or low disease risk estimate, the researchers still observed no difference between the groups. They did find, however, that receiving a genetic risk estimate was associated with an increase in physical activity among women, though not among men.
Griffin and his colleagues also asked participants whether they altered their diet or lost weight and gauged their levels of anxiety or worry changed, but again found no difference between the groups.
The researchers did, though, find that participants who received a risk estimate had a better understanding of such information. At baseline, participants typically overestimated their risk, but those who received risk estimates had a more accurate perception of their risk afterwards.
"The findings of this study suggest that the provision of genetic risk information, which reduced perceived risk in the majority of participants, did not motivate healthy changes in behavior over and above phenotypic risk information or standard lifestyle advice alone," Griffin and his colleagues wrote.
They noted that the participants might not have been motivated to make changes as most overestimated their risk of disease and might have been reassured by their results.