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Article Type: Guest editorial From: Journal of Public Mental Health, Volume 14, Issue 1.
Uy Hoang, Sarah E.M. Crouch, Lee Knifton and Carol Brayne
Dr Uy Hoang is Clinical Research Fellow at the Nuffield Department of Population Health, University of Oxford, Oxford, UK.
Sarah E.M. Crouch is based at Faculty of Public Health - Mental Health Committee, London, UK.
Lee Knifton is Reader and Co-Director at the Centre for Health Policy, Faculty of Humanities & Social Sciences, Strathclyde University, Glasgow, UK.
Carol Brayne is based at Cambridge Institute of Public Health, University of Cambridge, Cambridge, UK.
Dementia - the challenge of putting the horse before the cart
Dementia is "a global challenge and a public health priority" accordingly to Dr Margaret Chan, director general of the World Health Organization in a speech she delivered to a recent G8 summit on the condition. Her sentiments are shared by many current political leaders including Barack Obama and David Cameron, the UK prime minister who hosted the summit in London last year. He described it as "the biggest challenge we face today" (UK Department of Health, 2012). In addition to organising international initiatives, many countries including Australia, Japan, Korea, Netherlands, Norway, France and the UK have also recently published national dementia plans setting out their own strategies to tackle this challenge (Alzheimer's Disease International). The plan outlined by the Obama administration is possibly the most ambitious and has called for an effective treatment by 2025 (US Department of Health and Human Services, 2011).
The focus and widespread political consensus on dementia is surprising given that it is a condition where the aetiological mechanisms are not clearly delineated, and there is currently no treatment to reverse its effects. However, dementia, especially research into the condition has been drawn into the spotlight, thus it is helpful to remind ourselves of the challenge and reflect on the research that still needs to be done.
Dementia is a term used to describe a set of symptoms that can include loss of memory, mood changes and problems with communication and reasoning. The most common reasons for these symptoms are Alzheimer's disease, a condition characterised by changes in chemistry and brain structure; and vascular dementia, characterised by problems with blood supply to the brain. In "usual" dementia, occurring in the ninth decade and beyond forming the majority of cases in the UK, the pathology found in the brain after death is almost always a mixture of these two with or without additional ones. However, there is a substantial minority of people that die with these pathologies in their brains but who have not become clinically demented during their lifetimes.
There are an estimated 35 million people with dementia worldwide, with approximately 800,000 in the UK, and 58 per cent living in low- or middle-income countries. Initial estimates suggested that this figure would double in the next 20 years to 65 million by 2030 (UK Department of Health, 2012; Prince et al., 2013), although more recent evidence from both North America and Europe, including the UK suggests that there may be a stabilisation of the numbers estimated to reach particular diagnostic criteria (Matthews et al., 2013). It seems unlikely that these changes can expect to be the same across cultures and cohorts experiencing vastly different influences across the lifecourse.
The impact of the condition on an individual is variable depending on their personality, severity of symptoms and level of social support. However, the cost of formal and informal care, including health and social care services are substantial, with current financial costs estimated at £23 billion a year in the UK (Alzheimer's Society, 2012) and 1 per cent of global GDP or $600 billion (Alzheimer's Disease International, 2010). These figures are also set to rise in the following decades.
Disease-specific primary prevention strategies for dementia currently remain elusive (Haan et al., 2004; Perissinotto et al., 2011; Richard et al., 2010). Given the mixed nature of most dementia, prevention strategies for tackling single diseases, if effective, are unlikely to tackle all of any one individual's underlying "causes" of dementia. Across the lifecourse many factors have been proposed as being protective or increasing risk. Studies looking at the role of antioxidants and other vascular risk factors in primary prevention (e.g. hypertension: McGuinness et al., 2009, statin therapy: McGuinness et al., 2009) have proved inconclusive. Some of the most promising data relate to encouraging physical activity (Jedrziewski et al., 2010; Rockwood et al., 2007), tackling depression, encouraging participation in cognitively stimulating exercises and facilitating social engagement (Middleton et al., 2009; Wilson et al., 2002). Trials have been rather limited. In addition the extent to which future projections of numbers of people with dementia may be modified by implementing these primary preventative measures is unknown. Models outlining the effects of primary prevention have been attempted but are complicated and not entirely helpful (Brayne et al., 2001).
Secondary prevention by screening for early symptoms or else encouraging early diagnosis is controversial despite its recommendations in the NICE dementia care pathway, as there is no clear evidence that diagnosis before the usual point of clinical presentation can be readily and reliably performed or that it leads to long-term improvements for people with dementia and their families and reduces health care cost (Brunet et al., 2012). A number of systematic reviews into the evidence base for population screening of dementia have been found to have no evidence, no clinical benefits and the US Prevention Task Force recently renewed their statement that screening for dementia in primary care settings does not have sufficient evidence to support its introduction (Lafortune et al., 2013; Lin et al., 2013; Moyer, 2014).
Interventions for people who already exhibit symptoms of dementia to arrest the progression to the disease, prolong survival and improve quality of life are somewhat better evidenced and have been outlined in the NICE dementia guidelines (NICE, 2006). These include interventions to alleviate cognitive symptoms and maintain function, such as acetylcholinesterase inhibitors (limited in their general impact although effective for some) and structured group cognitive stimulation programmes, as well as interventions to tackle co-morbid anxiety and depression.
Thus there remain major gaps in the evidence base for a public health and prevention-focused approach to dementia, as highlighted by a number of groups including the Dementia Priority Setting Partnership (a consortium initiated by the Cambridgeshire and Peterborough Collaborative Leadership in Applied Health Research and Care and the Alzheimer's Society, working in collaboration with the James Lind Alliance), the MRC's Ministerial Group in Dementia Research (MAGDR) which is now the Dementia Challenge Research Committee (chaired by Dame Sally Davies), and the NIHR dementia research workshop which identified priorities for research related to the cause, cure and care of people with dementia, including research on health service development and community engagement. Specific areas where further research is required are in ethnic minority groups which are typically under-represented (Cooper et al., 2010; Lampley-Dallas, 2002; Mukadam et al., 2011), as well as studies that in low and middle incomes countries which bear the burden of prevalent cases (Prince, 2000).
However, there are considerable barriers to undertaking research in this field not least the difficulty of recruiting suitable patients and following them over many years in longitudinal studies. The EU Joint Programme in Neurodegenerative Disease Research (JPND) and the MRC through the UK dementias research platform are currently exploring the value of existing longitudinal studies for studying the aetiology and progression of dementia (JPND Research, 2013; Medical Research Council, 2014). In addition the MRC have put forward the possibilities of linking to emerging networks of NHS memory clinics to create a national register of patients (Medical Research Council, 2011).
Thus an evidence-based public health approach to dementia is currently limited, despite the clear need for prevention in the face of a growing epidemic of dementia. The temptation from policy makers has been to rush to formulate public health policies and introduce interventions, with little evidence of effectiveness and little in the way of evaluation (Le Couteur et al., 2013).
This piecemeal approach to public health policy implementation is at odds with the usual approach where such preventative interventions have not been introduced until the weight of evidence on effectiveness, cost benefit, social and health service training implications and system and societal readiness is fully worked through. It risks creating adverse effects and limits the possibility of gaining valuable knowledge about what works (Raffle et al., 2007; Sackett et al., 1975).
One such example in the UK and USA is the introduction of an annual cognitive screen in primary care to tackle the perceived under-diagnosis of dementia (Alzheimer's Society, 2011), and to facilitate early referral to specialist services, prevent avoidable admission to hospital and prevent longer hospital stays. In the UK, this is referred to in the NICE clinical guideline on dementia which states that a basic dementia screen should be performed at the time of presentation, usually within primary care (NICE, 2006). The QOF also rewards GPs who undertake a battery of tests for patients they suspect of having dementia. Neither of these interventions are evidenced based and diagnostic creep, namely shifting diagnostic boundaries until normal sorts of mental functions and the vicissitudes of life are defined as abnormal, essentially pathologising human behaviour is a real risk for such a non-evidenced policies (BMJ, 2012; Rosen et al., 2008). As pointed out by Professor Clare Gerada, President of the Royal College of General Practitioners, screening for minor memory loss in an elderly population risks medicalising normal ageing.
Brayne and colleagues have called for a more coordinated approach between governments, charities, the academic community and others to be ensure that the research gaps are plugged and that there is a closer alignment between health care policy in dementia and the scientific base for health services or clinical intervention (BMJ, 2013; Le Couteur et al., 2013).
Political will has created an opportunity to tackle this public health issue, and the expansion of investment in research aimed at reducing the impact of dementia is welcomed. For example research aimed at reducing health inequalities and improving the experience of living with dementia will have an effect on quality of life for people with dementia and may have a lasting impact on prevalence.
However, the added sense of urgency that political leadership also risks subverting the usual process of generating health policy and advocating public health interventions arising from robust scientific evidence. We must be careful not to let the policy cart come before the research horse, otherwise we risk squandering the opportunity that we have to really make a step change in dementia research and care for dementia patients.
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