Abstract
There is a growing evidence base linking modifiable health and lifestyle factors to risk of dementia. Susan Mitchell, Claire Lucas, Matthew Norton and Laura Phipps of Alzheimer’s Research UK suggest it may never be too early or late to start reducing the risk.
There are 850,000 people living with dementia in the United Kingdom today, and there is currently no disease-modifying intervention available for any form of the condition. Costs from dementia to the UK economy are currently estimated to be over £24 billion a year and approximately 700,000 people are informal carers for people who have dementia. While age is the biggest risk factor for developing dementia, the condition is not an inevitable part of ageing. Other factors such as medical history, lifestyle and genetics may also contribute to the risk of developing dementia. Although the evidence base is not complete, on the basis of current understanding, up to 30% of Alzheimer’s cases may be preventable through modifiable health and lifestyle factors. 1 While progress is being made to find a treatment or cure, there is an immediate need to focus on this potential to reduce the number of people developing dementia.
A recent analysis of the research on protective and modifiable factors for dementia 2 concluded that there is strong evidence to show that stroke, midlife high blood pressure and diabetes increase the likelihood of developing dementia. In many cases, risk of these conditions can be minimised through lifestyle choices – cutting out smoking, eating a healthy diet with low alcohol consumption, keeping physically active and maintaining a healthy weight. There is also evidence of a direct link between smoking and an increased risk of dementia, with much of the research to date focusing on Alzheimer’s disease. 2 It is important to note that the evidence applies to populations rather than individuals so there is no guarantee that by following all the advice, an individual will avoid developing dementia.
The evidence suggests that some factors will have more influence on the risk of developing dementia at different times in life. It is thought that damage caused by risk factors, or the lack of protective factors, can accumulate over a lifespan, potentially resulting in the clinical onset of dementia. 2 For example, education in early life is found to have a protective effect, 3 whereas managing hypertension may be particularly important in midlife. 2 There is also evidence that ex-smokers have a lower risk of dementia than current smokers: early indications suggest it may never be too early or too late to start reducing your risk of dementia.
While a recent study 4 suggested that the incidence of dementia in the United Kingdom has fallen, potentially in response to changing health and lifestyle habits, there is concern that rising diabetes and obesity rates could buck this trend in future years. Given that there is very limited public understanding of the potential impact risk factors can have for dementia, 5 there is a need for action from public health professionals and policy-makers.
There has been ongoing debate within the scientific community about whether the current evidence base is robust enough to draw recommendations for the general public. It is very difficult to prove causation as most of the evidence is based on observational research, and the differences in the design of studies make comparison and pooling of results difficult. Furthermore, studies often follow small groups of people or are conducted over short periods of time. Encouragingly, policy-makers have engaged with the developing evidence base and the Blackfriars Consensus 6 was published in 2014. This statement, signed by 59 organisations and experts from across the UK dementia and public health community, concluded that there is sufficient scientific evidence to enable people to begin to act to reduce their risk of developing dementia. Since then, Public Health England has made dementia risk reduction one of their seven priorities, the National Institute for Health and Care Excellence (NICE) has published public health guidance on midlife interventions to reduce dementia in later life and risk reduction is a key aspiration of the Prime Minister’s challenge on dementia 2020 for England. Dementia risk reduction is now part of the National Health Service (NHS) Health Check for 40- to 74-year-olds, although it only offers information to those over 65.
There are two major challenges ahead. First, while there has been considerable high-level engagement with dementia risk reduction, the task now is to ensure that messaging reaches and influences the public. There remains considerable stigma and misunderstanding around dementia; it is the most feared health condition among people aged 55 and over in the United Kingdom (36%), 7 and many people think that it is simply an inevitable part of getting older. Getting people to think about a condition that they might not develop for another 40 years is not easy. However, given that the messages are broadly the same as for good cardiovascular health, we need to ensure that dementia is incorporated into wider non-communicable disease messaging. To support progress in this area, Alzheimer’s Research UK and Public Health England have produced a dementia risk reduction booklet for the public. 8
Second, there remain many gaps in the evidence base and there is limited understanding of which health interventions are most effective for the identified risk factors. The risk reduction research community has faced numerous challenges due to a lack of funding, problems in sharing data, disincentives for collaboration and methodological difficulties. Overall, there has been a lack of strategic leadership to focus priorities and overcome these challenges. With the greater political and policy focus now afforded this field, we are working with colleagues across the United Kingdom to capitalise on this momentum to address these issues, solidify the evidence base and ensure that high-quality research evidence is informing strategic approaches to risk reduction on a population level.