Dementia Incidence Continues to Increase with Age in the Oldest Old The 90+Study

Department of Neurology, University of California, Irvine, CA 92697-1400, USA.
Annals of Neurology (Impact Factor: 9.98). 01/2010; 67(1):114-21. DOI: 10.1002/ana.21915
Source: PubMed

ABSTRACT The oldest old are the fastest growing segment of the US population, and accurate estimates of dementia incidence in this group are crucial for healthcare planning. Although dementia incidence doubles every 5 years from ages 65 to 90 years, it is unknown if this exponential increase continues past age 90 years. Here, we estimate age- and sex-specific incidence rates of all-cause dementia in people aged 90 years and older, including estimates for centenarians.
Participants are from The 90+ Study, a population-based longitudinal study of aging and dementia. Three hundred thirty nondemented participants aged 90 years and older at baseline were followed between January 2003 and December 2007. Age- and sex-specific incidence rates of all-cause dementia were estimated by person-years analysis.
The overall incidence rate of all-cause dementia was 18.2% (95% confidence interval [CI], 15.3-21.5) per year and was similar for men and women (risk ratio, 0.94; 95% CI, 0.65-1.37). Rates increased exponentially with age from 12.7% per year in the 90-94-year age group, to 21.2% per year in the 95-99-year age group, to 40.7% per year in the 100+-year age group. The doubling time based on a Poisson regression was 5.5 years.
Incidence of all-cause dementia is very high in people aged 90 years and older and continues to increase exponentially with age in both men and women. Projections of the number of people with dementia should incorporate this continuing increase of dementia incidence after age 90 years. Our results foretell the growing public health burden of dementia in an increasingly aging population.

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Available from: María M Corrada, Jun 20, 2014
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    • "A lzheimer's disease (AD) is the pathological cause of the most common dementia in the world, and as many as 50% of people older than age 85 may be afflicted (Corrada et al., 2010; Evans et al., 1989; Fitzpatrick et al., 2004). The diagnostic hallmarks of AD are neurofibrillary tangles and amyloid plaques that are easily identified in postmortem examination (Braak and Braak, 1991), and more recently with in vivo brain imaging techniques (Frisoni et al., 2013). "
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    Brain Connectivity 03/2014; 4(5). DOI:10.1089/brain.2013.0208
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    • "The Eurodem collaboration provided the first large prevalence study as they pooled multiple studies across Europe, and reported that dementia prevalence and incidence continue to increase dramatically with age, even beyond age 90 [29]. More recently, the 90+ Study confirmed that dementia prevalence and incidence continue to increase after age 90, but only for women [6,30]. The prevalence of dementia was found to double roughly every 5 years such that 27% of women aged 90 to 91 were diagnosed with dementia compared with 71% of women aged 98 to 99. "
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    • "Some studies have reported that incidence levels slow down after an age of 90 years (Miech et al., 2002), but these findings remain controversial. A recent analysis indicated that dementia incidence may continue to increase and that previous observations of a plateau may be due to sparse data for the oldest-old (Corrada et al., 2010). The economic impact of dementia is already enormous with total costs of more than s177 billion in Europe solely in 2008 (Wimo et al., 2011). "
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