3 December 2018
Saskia C Sanderson PhD is a Senior Research Fellow at the Institute of Health Informatics at University College London. Currently her research focuses on the value of personal genomics for mental and physical health. Watch Saskia's TEDx talk 'Would you have your genome sequenced?'
When we talk about psychological and behavioural effects of disease risk information based on genetics, we are talking about questions of ‘utility’ or value. In other words, will having this information prompt behaviours or actions that improve health outcomes for any given person?
Many factors influence a person’s risk of developing diseases such as cancer and heart disease, of which our genes are but one. But understanding of the complex interplay between genes and other risk factors is improving. Over the coming years it is likely people are going to get more – and more personalised – information about their disease risks based on genetic factors combined with other biomarkers, lifestyle factors, and demographic factors. But what is the value of telling people their future risk of developing, for example, breast cancer or type 2 diabetes, based on their genes? Does it cause more good than harm, or more harm than good?
These are questions that I and other psychologists exploring the impact of genetic risk information on individuals are asking. Research is continuing but a picture is gradually emerging based on the evidence so far.
Physical diseases such as breast cancer, colon cancer, heart disease, and type 2 diabetes develop from early stage to late stage disease over time. Offering people in the general population personal disease risk information based on tests for rare variants in their DNA and polygenic risk scores could potentially identify people at very high genetic risk of these types of diseases. This in turn might enable risk-reducing strategies to be targeted to these individuals early in life, before they or their relatives have developed late-stage disease.
Research is underway to understand whether and how risk-stratified approaches to disease prediction and early detection can best be delivered in healthcare systems, including their acceptability across society. Such acceptability will depend in part on whether it turns out that this type of knowledge of personal genetic risk does actually empower people to engage in behaviour changes that reduce their risk, or whether instead it simply increases anxiety and fatalism without leading to any benefits.
There is some preliminary evidence to suggest that genetic risk information might encourage people to take medications, make clinical appointments or discuss their results with clinicians, go for screening such as imaging (e.g. mammogram) that they wouldn’t otherwise have engaged in, or even have surgery. The hope of course is that high-risk results will prompt risk-reducing clinical actions. More research is needed though to know whether these actions do actually reduce disease risk over time for these individuals, and whether any benefits outweigh harms such as ‘overdiagnosis’ of early stage disease.
So far, it seems not. The early evidence on genetic testing and lifestyle change suggested people generally don’t change their lifestyle behaviours based on genetic risk information. The reasons behind what and how much people eat, how much alcohol they drink, whether they smoke, and how physically active they are, are very complex: given genetic information is just one piece of a many-pieced jigsaw, we are unlikely to be able to change people’s lifestyle behaviours with genetic ‘fear appeals’ alone. If presented as part of a whole picture along with other personalised health information and support, genetic risk information might bolster recommendations to change certain health related behaviours in the future. But on its own, evidence to date suggests genetic information is unlikely to have a powerful effect on lifestyle behaviours.
In the long term, probably not. Receiving genetic risk information about diseases such as breast cancer can, understandably, temporarily raise concern in an individual – but these negative emotional effects are usually minimal and short-lived. As long as people have made informed decisions, have adequate psychosocial support, and/or have the means to reduce or manage their disease risk, evidence to date suggests that emotional distress tends to subside.
People rarely if ever respond to genetic information by being falsely reassured! There is no evidence to suggest people respond to low risk genetic information by thinking it’s safe for them to eat and drink whatever they want because a disease is ‘not in their genes’. Nonetheless, it remains incumbent on providers to communicate genetic risk information in ways that ensure recipients understand the meaning of the risk information, whether it indicates high, average or low risk.
Compared to research on the impact of genetic risk information about physical diseases on individuals, research on the impact of genetic information about mental health is in its infancy. However, the field of psychiatric genetics is advancing rapidly. As more is revealed about the role of genetics in mental health, will people respond differently to genetic risk information about predisposition to, for example, depression or bipolar disorder, than they do to physical disease? And will genetic predisposition increase socio-economic stigma and bias? The truth is we simply don’t know yet. But this is why it is vital that research is conducted to inform policy regarding using genetic information about mental health and wellbeing, as well as physical health.
Evidence to date suggests that there are neither significant benefits nor harms of giving people personal genetic risk information about complex multifactorial diseases – seemingly leaving us unclear as to the medical value of giving this information to patients. However, the first human genome was only sequenced fifteen years ago, and most of the psychological and behavioural research conducted to date in this space over the last decade has been based on very early types of genetic risk information. As genomics research is increasingly based on hundreds of thousands and soon millions of genomes, the landscape is rapidly changing. Over the next ten years we are likely to see significant progress in understanding how genetic factors contribute to health and wellbeing. Concerted effort is needed now to generate evidence on the value of giving people genetic information about themselves, and how this information can best be communicated and delivered equitably for the benefit of patients and society.