Are cognitively impaired individuals adequately represented in community surveys? Recruitment challenges and strategies to facilitate participation in community surveys of older adults. A review

Background: Dementia is the most important age-related disorder and subject to a substantial body of epidemiological research. However, field work in elderly populations faces special challenges which may reduce response rates and invalidate survey results. Therefore, this paper will review more recent prevalence studies of dementia to examine how recruitment issues and their influence on the study outcome have been addressed. Methods: Field studies of the elderly with the main focus on prevalence of dementia published over the last 10 years will be systematically reviewed. The review concerns sampling frames, ways to include institutionalised individuals, response rates and strategies to deal with special challenges of field work in elderly populations such as mortality, fragility and sensory impairment. Furthermore, papers were evaluated regarding the extent to which recruitment outcomes were discussed. Results: The literature is characterised by a disregard of recruitment issues to a varying extent. Mortality, functional dependency and sensory impairment (all positively related to dementia) are barely taken into account in the study design and rarely discussed. As a consequence, cognitively impaired individuals are likely to be underrepresented in most community studies. Conclusion: Strategies to deal with special challenges of field work in the elderly in a systematic manner and to facilitate participation in population surveys of the elderly are crucial and will be outlined. Communication on recruitment issues is essential to improve the validity of study outcomes.     

Predictive factors of hospitalizations in Alzheimer’s disease: A two-year prospective study in 686 patients of the REAL.FR study

Background  

During the course of the Alzheimer’s disease (AD), many patients need to be hospitalized either due to the direct consequences of the disease itself, or due to associated diseases or life event. The objective of the present study was to determine predictive factors for hospitalisation in AD patients.     

Frailty in relation to the risk of Alzheimer’s disease,dementia, and death in older Chinese adults: A seven-year prospective study

Objectives

To explore the relationship of general health decline assessed by frailty and risk of dementia and Alzheimer’s disease (AD).

Design

A seven-year prospective cohort study.

Setting

Secondary analysis of data from the Beijing Longitudinal Study on Aging.

Participants

Urban and rural communitydwelling people aged 60 and older at baseline.

Measurements

Frailty was quantified using the deficit accumulation-based frailty index (FI), constructed from 40 health deficits at baseline. Dementia was diagnosed by DSM-IIIR. AD and vascular dementia (VaD) were diagnosed by NINCDS-ADRDA and NINDS-AIREN. The relationships between frailty and the risk of dementia, AD and death were evaluated through multivariable models.

Results

Of 2788 participants at baseline (1997), 171 (11.1%) reported a history of dementia. In seven years, 351 people developed dementia (13%: 223 AD and 128 other types of dementia) and 813 died (29%). After adjustment for age, sex, education, and baseline cognition, baseline frailty status significantly associated with Alzheimer’s disease and dementia and death. For each deficit accumulated, the odds ratio of death increased by 5.7%, and the odds ratio of dementia increased by 2.9% (p < 0.001).

Conclusion

Frailty was associated with Alzheimer’s disease and dementia over a seven years period. Frailty index might facilitate the identification of older adults at high risk of dementia for the application of the most effective, targeted prevention strategies.