Select Committee on Science and Technology Minutes of Evidence

Memorandum by Professor Carol Brayne


  This written contribution draws on experience as a lead principle investigator in longitudinal studies of older people over nearly two decades, as well as medical and public health training. I have consulted colleagues from the main study for which I am responsible, the MRC funded Cognitive Function and Ageing Study (MRC CFAS).


  We have reported from this multicentre study in England and Wales that:

    —  prevalence and incidence of disability, cognitive impairment and dementia rise exponentially after the age of 65;

    —  there is no down turn at the oldest age groups;

    —  there is variation across the centres in disability but not in dementia;

    —  pathology found in the brain after death at advanced age is found in both those who are cognitively impaired during life and those who are not and is mostly a mixture of vascular and Alzheimer's type;

    —  substantial proportions at each age, including the oldest age groups, report good health despite increasing health problems;

    —  very high proportions are demented in the period before death, particularly in the oldest age groups;

    —  potential genetic risk for Alzheimer's disease appears attenuated by the time most people reach old age probably because of the high background risk to the whole population.

  The bibliography and design of CFAS are described in more detail at


  It can be helpful to see research findings as fitting into a prevention framework. Each of these types of prevention has a different impact at the population level (from highly effective to minimal) but all are important.

  Primary prevention (reducing "risk" exposure so that pathology does not develop). This type of prevention has the greatest potential yield if applied to populations. There are a great deal of observational data from epidemiological studies which suggest that certain types of lifestyle/opportunity (at all lifestages) are associated with less chronic disease and health active life expectancy. Bringing such results into feasible trials of intervention at appropriate level (individual, social network, community, high level policy) which generate sound data are far less common—and tend to be done at individual rather than community levels, lowering population impact.

  The Wanless report has identified such public health research as an area for active development and this needs to be carefully encouraged—with a build up of the expertise necessary and an environment that facilitates research. Such research has to be built on firm disciplinary research, but then brought together into the complex intervention framework (well work up by the MRC). This type of research tends to take a long time and not result in multiple publications in high ranking journals—so needs positive nurturing. Current assessment and funding systems do not encourage such long term high risk investment for researchers, research groups, universities and funders. Some areas potentially important to health, but not traditionally researched as such, have been identified in the imminent ESRC call, but with limited funding and include the role of built environment (housing, transport, the way the built environment makes us active or inactive), intergenerational aspects, civic society, crime and disorder, accessibility and financial security. The new clinical networks being set up within the NHS for individual and groups of disorders have the potential to include only traditional therapeutic trials—it is important not to miss other types of intervention. Research which aims to investigate population behaviour at any age could have knock on effects for each cohort as future health is a function of current and past health.

  Secondary prevention (early detection and alteration of natural history through early intervention). This has the potential to modify population health to some extent, if all the criteria necessary for screening are met. Not many interventions have been tested on older age groups, and this will continue to be an area of important research. The MRC has funded research into a trial of screening in the older population, which is now yielding results (which, importantly, can have negative findings as well as positive). Such trials have the same problems as interventions in primary prevention but their feasibility on a very large scale is proven, provided that populations can continue to be recruited through the primary care setting. The UK can provide amongst the best evidence internationally because of this ability to recruit from clearly defined populations.

  Tertiary prevention (prevention of the consequences of disease once established). This type of research has the least potential impact on population health. There is insufficient follow-up on new and costly introductions of interventions, once short term trial evidence is released, such as the dementia treatment drugs, to see what real impact they have on the natural history of morbidity and ultimately mortality.


  In the understandable concentration on healthy ageing and reduction of morbidity at given ages there has been less attention to the consequences of prevention earlier in life, and its impact on future populations reaching the oldest age groups. The relationship of changing health and wellbeing to survival, with quality of life and death has been less researched but is bound to receive increasing attention as the whole population ages. Dementia or severe cognitive impairment is very common in the period before death in the oldest age groups. This is unlikely to be prevented in the near future, if ever and we need to understand this stage of life too. A firmer foundation of research is needed to prepare for this societal change, including the frail stages of ageing not just "healthy active" life.


  Work on modelling population health profiles including more detail in older age groups given changes in younger age cohorts is not highly developed and is an area of potential value. Although many are sceptical about the value of modelling it is valuable for policy assessment, particularly if carried out with sensitivity analyses and explicit discussion of uncertainty. This has been identified as an area by the Wanless report, and the MRC has asked HEIs to bid for dedicated doctoral studentships. Continuing support is needed to build up this area of expertise in the UK.


  Encouragement of a diversity of approaches to ageing research is sensible as each can reveal valuable insights which can be tested from a different angle in another (disease, system, lifestage, holistic, discipline based approaches, single and multidisciplinary), not least to provide sound evidence for modelling. Major gaps for which there are currently no large-scale research efforts are epidemiological studies examining variation in health across ethnic groups and cohorts in the oldest age groups. Such studies are most valuable if they have a robust population base and if they can have a set of more detailed biomedical and qualitative studies bolted on. MRC CFAS, amongst others, can provide a model for this type of approach, which can then be used to address biological questions (such as why rates of dementia might vary across populations) as well as policy questions (do we expect different patterns of ageing as our ethnic populations move into the older age groups, are future older people likely to be more healthy or less than now). These questions can only be explored with stable methodology and population sampling. The opportunity does exist but has not been taken up.


  There are now major barriers to research beyond achieving funding including the many levels of permission and engagement required to work with populations, from research governance structures (multiple within the NHS), ethical review and the legislative framework such that more time is spent in these processes than in the research itself.

September 2004

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