A study of dementia in a rural population

Dementia, in particular Alzheimer's disease, has been widely investigated in clinical settings. Moreover, many epidemiological studies have been carried out to estimate the prevalence and incidence of dementia and, less frequently, Alzheimer's disease. There have also been studies of ageing cohorts to examine mental changes associated with ageing. There has, however, been little research on unselected elderly populations which has been detailed enough to examine the relationship between normal and abnormal mental ageing. The aim of this study was to investigate the distribution of the indices of dementia in a rural population. This allowed investigation of the hypothesis that variables associated with dementia, in particular Alzheimer's disease, are distributed bimodally in the population and allowed investigation of possible associations with these distributions. It also provided prevalence estimates of dementia in a rural population. A population sample of women aged 70 to 79 was selected from a rural Cambridgeshire health centre. Using the Cambridge Examination for Mental Disorders in the Elderly all aspects required for the diagnosis of dementia and tentative differential diagnosis were collected on 365 women. There was no evidence of bimodality in any of the derived scales, whether cognitive, behavioural or ischaemic. The prevalence of dementia of all types and levels, including mild, was 4.3% in the 70 to 74 age group and 11.7% in the 75 to 79 age group. For more severe dementia a prevalence of 2.8% was found in the 75 to 79 age group, and 0% in the 70 to 74 age group. The rates for more severe dementia were lower than other recent prevalence studies in the UK, whereas the rates for all levels of severity were higher. The tentative diagnosis of Alzheimer's disease accounted for 52% of the diagnoses of dementia and multi-infarct dementia for 31%. Age, social class and education were all significantly and independently associated with scores on the longer cognitive scales (Mini-Mental State Examination and the CAMCOG scale of CAMDEX). Risk factors suggested in the literature for dementia, Alzheimer's disease and cognitive impairment was also investigated. Few factors were associated with either cognitive function or dementia. Age was the only variable associated with both cognitive function and the diagnosis of dementia. Only small proportions of the population were exposed to postulated risk factors and these risk factors, if proven, would account for little population excess risk. In this study no significant separation of performance on cognitive or behavioural scales between the demented and the non-demented was found. This could have been due to the small numbers in the tails of the frequency distributions but, if true, it is suggested that this observation might be related to the continuous distribution of underlying neuropathological lesions, such as plaques and tangles, noted in autopsy series of unselected populations. If so, current research into the mechanisms of the dementias may have implications for the understanding of cognitive decline noted in the non-demented elderly over time

Population-based neuropathological studies of dementia: design, methods and areas of investigation--a systematic review.

BACKGROUND: Prospective population-based neuropathological studies have a special place in dementia research which is under emphasised. METHODS: A systematic review of the methods of population-based neuropathological studies of dementia was carried out. These studies were assessed in relation to their representativeness of underlying populations and the clinical, neuropsychological and neuropathological approaches adopted. RESULTS: Six studies were found to be true population-based neuropathological studies of dementia in the older people: the Hisayama study (Japan); Vantaa 85+ study (Finland); CC75C study (Cambridge, UK); CFAS (multicentre, UK); Cache County study (Utah, USA); HAAS (Hawaï, USA). These differ in the core characteristics of their populations. The studies used standardised neuropathological methods which facilitate analyses on: clinicopathological associations and confirmation of diagnosis, assessing the validity of hierarchical models of neuropathological lesion burden; investigating the associations between neuropathological burden and risk factors including genetic factors. Examples of findings are given although there is too little overlap in the areas investigated amongst these studies to form the basis of a systematic review of the results. CONCLUSION: Clinicopathological studies based on true population samples can provide unique insights in dementia. Individually they are limited in power and scope; together they represent a powerful source to translate findings from laboratory to populations

A comparison of parametric models for the investigation of the shape of cognitive change in the older population.

BACKGROUND: Cognitive decline is a major threat to well being in later life. Change scores and regression based models have often been used for its investigation. Most methods used to describe cognitive decline assume individuals lose their cognitive abilities at a constant rate with time. The investigation of the parametric curve that best describes the process has been prevented by restrictions imposed by study design limitations and methodological considerations. We propose a comparison of parametric shapes that could be considered to describe the process of cognitive decline in late life. Attrition plays a key role in the generation of missing observations in longitudinal studies of older persons. As ignoring missing observations will produce biased results and previous studies point to the important effect of the last observed cognitive score on the probability of dropout, we propose modelling both mechanisms jointly to account for these two considerations in the model likelihood. METHODS: Data from four interview waves of a population based longitudinal study of the older population, the Cambridge City over 75 Cohort Study were used. Within a selection model process, latent growth models combined with a logistic regression model for the missing data mechanism were fitted. To illustrate advantages of the model proposed, a sensitivity analysis of the missing data assumptions was conducted. RESULTS: Results showed that a quadratic curve describes cognitive decline best. Significant heterogeneity between individuals about mean curve parameters was identified. At all interviews, MMSE scores before dropout were significantly lower than those who remained in the study. Individuals with good functional ability were found to be less likely to dropout, as were women and younger persons in later stages of the study. CONCLUSION: The combination of a latent growth model with a model for the missing data has permitted to make use of all available data and quantify the effect of significant predictors of dropout on the dropout and observational processes. Cognitive decline over time in older persons is often modelled as a linear process, though we have presented other parametric curves that may be considered.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Is Dementia Screening of Apparently Healthy Individuals Justified?

Despite efforts to raise awareness and develop guidelines for care of individuals with dementia, reports of poor detection and inadequate management persist. This has led to a call for more identification of people with dementia, that is, screening individuals who may or may not complain of symptoms of dementia in both acute settings and primary care. The following should be considered before recommending screening for dementia among individuals in the general population. Dementia Tests. Low prevalence reduces positive predictive value of tests and screening tests will miss people who have dementia and identify people who do not have dementia in substantial numbers. Clinical Issues. The clinical course of dementia has not yet been shown to be amenable to intervention. Misdiagnosis and overdiagnosis can have significant long-term effects including stigmatization, loss of employment, and autonomy. Economic Issues. Health systems do not have the capacity to respond to increased demand resulting from screening. In conclusion, at present attention to life-course risk reduction and support in the community for frail and cognitively impaired older adults is a better use of limited healthcare resources than introduction of unevaluated dementia screening programs.Peer Reviewe

Community environment, cognitive impairment and dementia in later life: results from the Cognitive Function and Ageing Study

Background: Few studies have investigated the impact of the community environment, as distinct from area deprivation, on cognition in later life. This study explores cross-sectional associations between cognitive impairment and dementia and environmental features at the community level in older people. Method: The postcodes of the 2424 participants in the year-10 interview of the Cognitive Function and Ageing Study in England were mapped into small area level geographical units (Lower-layer Super Output Areas) and linked to environmental data in government statistics. Multilevel logistic regression was conducted to investigate associations between cognitive impairment (defined as MMSE3 in GMS-AGECAT) and community level measurements including area deprivation, natural environment, land use mix and crime. Sensitivity analyses tested the impact of people moving residence within the last two years. Results: Higher levels of area deprivation and crime were not significantly associated with cognitive impairment and dementia after accounting for individual level factors. Living in areas with high land use mix was significantly associated with a nearly 60% reduced odds of dementia (OR: 0.4; 95% CI: 0.2, 0.8) after adjusting for individual level factors and area deprivation, but there was no linear trend for cognitive impairment. Increased odds of dementia (OR: 2.2, 95% CI: 1.2, 4.2) and cognitive impairment (OR: 1.4, 95% CI: 1.0, 2.0) were found in the highest quartile of natural environment availability. Findings were robust to exclusion of the recently relocated. Conclusion: Features of land use have complex associations with cognitive impairment and dementia. Further investigations should focus on environmental influences on cognition to inform health and social policies

Public health research in the UK to understand and mitigate the impact of COVID-19 and COVID-19 response measures

This paper reflects concerns that funding and attention should be expanded from the important focus on those suffering and dying from COVID-19, and the safety and resources of healthcare professionals, to address wider questions on the (unequal) health and well-being impacts of COVID-19 and associated response measures. While immediate priorities such as those outlined in the WHO research agenda are undoubtedly important, additional urgent questions must be addressed. These include questions focused on (1) the non-virus impacts of preparing health and social care systems to cope with COVID-19 and (2) the health effects mediated by the educational, economic and social injuries sustained during the pandemic. Long-term, sustained and co-ordinated interdisciplinary research funding will be needed to address the long-lasting impacts of COVID-19 and its response measures

Dementia: time trends and policy responses.

In recent years, dementia has been considered a public health priority and become a topic of major political interest. Recent reviews and studies have reported with varying degrees of alarm an impending and existing "dementia epidemic" with increasing predicted trends in prevalence and enormous numbers of people with dementia particularly in low- and middle-income countries (LMICs). However, robust evidence from dementia research in high-income countries suggests stable or decreased prevalence over the last decades. Current evidence is not sufficient to suggest increasing trends of prevalence in LMICs once variation in methodological factors and study populations are taken into account. Changes in diagnostic methods over the last decades substantially influence the identification of dementia cases with systematic difference between the resulting individual prevalence studies. Potential geographical variations at the country level might indicate potential risk factors at population levels or systematic difference in clinical application of dementia diagnosis. Although it is important and necessary to use information from dementia research for evidence-based policymaking, over-interpretation of results without carefully considering underlying factors could exaggerate the findings and influence policy planning in ways which do not serve current and future population best. Planning of dementia policy needs to take full cognisance of the provenance of the data being used and be integrated with policies which optimise health across the lifecourse.Yu-Tzu Wu received a PhD scholarship from the Cambridge Trust, University of Cambridge. Fiona E. Matthews was supported by the Medical Research Council [grant number U105292687].This is the accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.maturitas.2014.06.02

Transient neurological symptoms in the older population:report of a prospective cohort study--the Medical Research Council Cognitive Function and Ageing Study (CFAS)

Transient ischaemic attack (TIA) is a recognised risk factor for stroke in the older population requiring timely assessment and treatment by a specialist. The need for such TIA services is driven by the epidemiology of transient neurological symptoms, which may not be caused by TIA. We report prevalence and incidence of transient neurological symptoms in a large UK cohort study of older people