Does personalized genetic information help people adopt healthier behaviour?

Giving people information about their individual risk of developing type 2 diabetes does not influence them to change their health-related behaviours, according to a study led by researchers from the MRC Epidemiology Unit, University of Cambridge and published today in PLOS Medicine.

Being more physically active and having a healthy diet can reduce the chance of developing type 2 diabetes, including for those who are at higher risk of developing the disease because of their genetic predisposition. Because genetic tests aimed at predicting the risk of type 2 diabetes are now widely available, there has been optimism that personalised genetic information will encourage people at risk to adopt healthier behaviours.

To investigate whether this is the case, researchers calculated the risk of developing type 2 diabetes for 569 healthy middle-aged adults the Cambridgeshire UK based Fenland study. These risk estimates were based either on the presence of 23 genetic markers known to be associated with type 2 diabetes, or on ‘phenotypic’ (i.e. physical) characteristics, such as sex, age and body mass index.

Participants were randomly assigned to different groups. Each group received standard lifestyle advice, which included general information about type 2 diabetes as well as information about how to reduce the risk of developing the disease. In addition to this information, one group of participants received a genetic risk estimate, while another received a phenotypic risk estimate. The remaining group of participants (the ‘control group’) received only lifestyle advice and did not receive either of the risk estimates until the end of the study.

After eight weeks, participants’ physical activity, self-reported diet and weight, anxiety, worry, and beliefs about their risk were measured. The researchers found that receiving genetic or phenotypic risk estimate did not in fact affect participants’ physical activity or other relevant behaviours, in comparison with those receiving only standard lifestyle advice. And whilst individuals’ perception and understanding of their own risk became more accurate, receiving this information did not seem to cause them worry or anxiety.

“This is one of the largest studies undertaken in this area, and unlike previous studies included precise, objective measures of behaviour,” said lead author Dr Job Godino, previously at the MRC Epidemiology Unit and now Assistant Professor in the Department of Family Medicine and Public Health at University of California San Diego.

It is notable that the information about risk was received and understood by participants, and that it did not cause anxiety. This is potentially reassuring for those concerned about negative psychological impacts of people receiving genetic risk information – something that is likely to increase in the future. In fact volunteers tended to overestimate their risk before receiving information, so there is the possibility that they were somewhat reassured by the information. This may be part of the reason it did not influence their behaviours, although it certainly did not make them adopt new unhealthy behaviours.”

This research follows meta-analysis by University of Cambridge researchers published earlier this year that found no evidence that genetic tests for a range of diseases change people’s behaviour.

“These new results give further weight to the argument that approaches that target individual behaviour change, such as communicating genetic risk, are unlikely to be successful without efforts to remove barriers to healthier behaviours in the wider environment and society,” said Prof Simon Griffin, Professor of General Practice at the University of Cambridge, and leader of the Prevention of Diabetes and Related Metabolic Disorders Programme at the MRC Epidemiology Unit.

“This is particularly relevant in light of the recent launch in England of the National Diabetes Prevention Programme. This programme is intended to work alongside NHS Health Checks which is providing people with information about their phenotypic risk of type 2 diabetes in the hope that this will motivate behaviour change and reduce diabetes risk. These new findings suggest that this provision is unlikely to have the desired effect on its own, and that it is important to develop policies that create a world that is more conducive to healthy behaviours.”

• Read the full paper: Personalized estimate of genetic or phenotypic risk of type 2 diabetes with lifestyle advice and objectively measured physical activity: a randomized controlled trial. Job G Godino et al, PLOS Medicine, 29/11/16 http://dx.doi.org/10.1371/journal.pmed.1002185