‘Personalized’ healthcare aims to offer specific, targeted advice for disease prevention based on genetic risk status, [1, 2]. Addition of information about genetic risk markers to standard care has been put forward as a way of empowering individuals to take responsibility for health maintenance, thereby maintaining quality of life and lowering healthcare costs . To date, the clinical utility of most genetic risk markers is assumed to be low because of the small effect sizes of genes identified for ‘common’ conditions. However, genetic testing can already be purchased over the internet without involvement of healthcare providers (for example, http://www.23andme.com; http://www.deCODEme.com), suggesting that consumers are interested in this kind of information. The idea that genetic test feedback could promote behavior change is consistent with psychological theories (such as protection motivation theory ) that identify perceptions of risk as important for motivating risk-reducing actions. Within this model, however, a lower-risk genetic test result might reduce motivation. An alternative perspective is that ‘genetic determinism’ (the idea that genetic effects cannot be modified) could lead to a fatalistic attitude towards health maintenance for example,  in the case of a higher-risk result, whereas a lower-risk result could induce a false sense of immunity and complacency for example, . Furthermore, there are concerns that individuals may discount their genetic result if it does not match their preconceived ideas about illness development . To date, few studies have investigated the consequences of genetic test feedback for common conditions. One approach uses ‘vignettes’ in which people imagine receiving a genetic test result and anticipate their reactions. Results for smoking cessation and prevention of weight gain suggest that higher-risk feedback increases motivation to change behavior and does not appear to induce fatalism [8–10], while lower-risk feedback does not appear to induce complacency, and may even have a mildly motivating effect . However, the gap between expressed intentions in the vignette context and actual behavior may be wide, so at best, these results only give an indication of the effects of actual test feedback.
‘Real’ genetic test feedback has received most attention in the smoking cessation field following the early discovery of genes coding for enzymes that reduce risk for lung cancer (GSTM1 and CYP2D6). There has been evidence of increased motivation to quit following genetic test feedback [11, 12], although a recent Cochrane review of five clinical studies failed to show any statistically significant effects on quitting when incorporating genetic feedback results into smoking cessation programs, either in the short term (two weeks), or in the longer term (six months) although study heterogeneity limited the interpretation of the results . However, the physiological and psychological drivers of nicotine addiction make smoking cessation particularly difficult to achieve, and quit attempts are marked by frequent relapse . Adding genetic test feedback in this context might be less influential than for other health promoting behaviors. The positive feature of these results was that there was no evidence that smokers receiving lower-risk results thought of themselves as immune to lung cancer for example, [12, 15]. This corresponds with findings from vignette studies, and indicates that complacency may not be a major concern. There is some evidence that inclusion of genetic test feedback for risk of obesity into clinical care may be beneficial. Feedback on a gene implicated in weight gain (bA3R) resulted in increased motivation to lose weight in a small sample of obese individuals . Another small qualitative study giving feedback on the FTO gene (also linked with weight gain), found that feedback increased motivation to lose weight (SFM and JW, unpublished). This study also found that the ‘scientific’ nature of the gene test result helped overweight participants feel less sense of personal failure and more confidence in managing their ‘condition’. A similar finding was reported in a community sample of overweight and obese adults, where genetic feedback reduced guilt and self-blame . Raising awareness of the genetic etiology of obesity also helps minimize negative stereotyping by healthcare professionals .
Thus far, most research has centered on the reactions of already affected individuals, but a key proposed application for genetic feedback is prevention of ill health. The one study in this area analyzed responses to receiving results from a direct-to-consumer genetic test for a panel of diseases in over 2000 people who volunteered to be followed up in return for purchasing their test at a reduced rate . Neither higher nor lower genetic risk for the panel of diseases was associated with changes in anxiety or health behaviors, nor were there changes in the number of health screening tests although intended use of health screening increased in the whole group. However, the participants in the study are likely to have been ‘early adopters’ of genetic testing who may be more health conscious than average and have less scope to change, supported by the fact that most of them were already following a low-fat diet. It is also possible that receiving results for a whole panel of diseases has a different effect from receiving results for a single condition because, inevitably, any high risk results are likely to be balanced by lower risk for others diseases, which may generate an overall null effect on risk perception. The present study will therefore investigate the impact of giving genetic risk feedback for a single condition, overweight, in conjunction with weight control advice, in a healthy, young adult sample entering a life stage where risk of weight gain is raised, to discover whether genetic feedback provides a ‘nudge’ toward unhealthy weight gain prevention. We will test the effect of adding feedback for the FTO gene, which has modest effects on weight gain and risk of obesity , to simple weight control advice. We use the university context because of evidence that first-year students have a high risk of weight gain (sometimes termed the ‘Freshman 15’ or ‘Freshman 5’) and low intentions to implement healthy behaviors [21, 22].
Study objectives and hypotheses
Primary research objective
The primary aim of the study is to test the hypothesis that adding genetic test feedback to weight gain prevention advice will result in higher motivation to prevent weight gain one month after receiving test feedback compared with receiving weight gain prevention advice alone.
Secondary research objectives
The secondary objectives are to assess differences in adherence to the advice and weight change from baseline to eight month follow-up in those receiving genetic test feedback and weight gain prevention advice compared with advice alone. We hypothesize that participants receiving genetic test feedback, regardless of risk status, will be more adherent to the advice and gain less weight over the study period than those receiving weight gain prevention advice alone. Within the group of participants receiving feedback and advice, we will also explore psychological reactions immediately after receiving genetic test feedback, and interactions between weight status and gene test status. We hypothesize that those receiving a higher-risk genetic test result will show higher negative affect but not higher fatalism in response to their genetic test result compared to those receiving an ‘average-risk’ genetic test result. We also predict that overweight participants receiving a ‘higher-risk’ result will value having an explanation for their weight more than normal weight participants, and that overweight participants will be more motivated to prevent further weight gain in response to a higher-risk genetic test result than those receiving an ‘average-risk’ result. All secondary objectives are exploratory, because of limited power.