Risk assessment and its role in prevention of dementia: lessons learned from other non-communicable diseases

Continuing our series of science commentaries Barbora Silarova and  Rachel Collins from the Universities of Exeter, UK and UNSW, Australia, consider whether lessons can be learned from other non-communicable diseases…

Dementia represents one of the biggest challenges for health and social care this century [1]. Since the development of a cure for dementia by 2025 is unlikely, prevention of dementia is now a key public health priority [2]. Currently, our efforts regarding  prevention of dementia and other non-communicable diseases are driven by the idea that once we know the risk factors associated with the disease, we can intervene and potentially prevent it [3]. As such, several reviews have been published in recent years quantifying the associations between risk factors and onset of dementia [4-6]. These risk factors are then usually combined into calculated risk scores [7, 8] enabling us to identify people who are at increased risk of disease and thus target finite preventative measures more effectively.

Risk scores

Risk scores have been well established for decades in e.g. cardiovascular disease [9] and type 2 diabetes [10] and are used as a fundamental part of most primary prevention strategies. In the UK, for example, they are used routinely within the National Health Service (NHS) Health Check [11] and NHS Diabetes Prevention Programmes [12], and their use is strongly advocated by both professional bodies [13, 14] and the National Institute for Health and Care Excellence (NICE) [15]. Public heath campaigns also encourage people to identify their risk of developing conditions such as diabetes [16] and the use of online risk score tools enables people worldwide to identify  their potential risk of developing different non-communicable diseases [17].

The use of risk scores aims to achieve several inter-related goals, including identifying those at greatest risk, improving risk perception for both physicians and patients, contributing to shared decision-making, targeting interventions and pharmacological treatments more efficiently and motivating individuals to improve their lifestyle with the ultimate goal of potentially preventing disease [15, 18]. With the shift in the field of dementia from cure to prevention, and the widespread use of risk scores in other fields of medicine and their popularity among health policy makers, the use of risk scores could be seen as an ‘easy solution’ to prevent a ‘dementia epidemic’. Before more research on dementia risk scores is conducted, however, and before these are implemented into clinical settings, we should be cautious and make use of emerging evidence regarding the utility of risk scores in primary prevention of other non-communicable diseases rather than starting our research efforts from scratch.

Lessons to learn

There are a few lessons that we can learn on this topic from studies conducted in other fields of medicine. Firstly, instead of spending large amounts of research funding on the development of new dementia risk scores, we should focus on validating the existing models and tailor these models to local settings or populations [9]. In cardiovascular research, for example, whilst there was an overwhelming number (363) of different prediction models in 2013, there was a paucity of external validation studies for most of these models [9], making it difficult for policymakers and health professionals to decide which cardiovascular disease risk score to use. A similar trend is also observed within the field of dementia. A systematic review published in 2010 identified over 50 different dementia risk scores but none of them were externally validated [7]. Since then many new dementia risk scores have been developed [8], the majority of which lack external validation.

Secondly, if the provision of dementia risk information becomes part of dementia preventive strategies, research is needed to identify the best and most appropriate methods of presenting dementia risk for both clinicians and patients. In the context of cardiovascular disease and cancer it has been shown that providing people with risk information does not alter risk perception among all participants equally [19, 20]. Presently, we understand that risk perception is not as simple as recalling a number. There are several suggestions as to why people sustain their own risk perception despite being provided with risk information, including personal understanding of disease and risk [21, 22], differences between laypersons’ understanding of risk information and clinical risk information [22, 23] and past experiences, expectations and beliefs [22, 24]. Similarly, evidence suggests healthcare professionals may find the communication of risk challenging [25, 26].

Lastly, policy makers, clinicians and some academics believe that once people are informed about their increased risk of developing a disease, they will adopt a recommended action in line with a theory of behaviour change [27-29]. There is no evidence, however, that simply providing patients with a number leads to statistically significant or clinically important changes in possibly environmentally-cued habitual behaviours such as diet, smoking, physical activity or alcohol intake [19, 30]. While there is no current evidence that risk provision translates into changes in lifestyle, small reductions in measurable factors such as cholesterol and blood pressure were seen consistently, possibly mediated through changes in prescribing [19].

What can we conclude?

To conclude, there are several challenges related to risk assessment and risk communication in the field of dementia; however, a lot can be learned from other non-communicable diseases. The most important lessons are related to the fact that risk scores do not provide a single, easy solution when it comes to prevention. Risk perception and health-related behaviours are complex and dynamic and unlikely to be changed by simple risk information. On the other hand, risk scores are useful tools to guide e.g. medication prescription and shared decision-making, so studies focusing on improving understanding of risk among both clinicians and patients should be a research priority. Naturally, if dementia risk scores become part of preventive strategies, it is fundamental that such risk scores must have good discriminative accuracy, predictive value and external validity.

References

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Author affiliations

Centre for Research in Ageing and Cognitive Health, School of Psychology, College of Life and Environmental Sciences, University of Exeter, EX4 4QG, UK

Centre of Research Excellence in Cognitive Health, University of New South Wales, Sydney, Australia

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