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Has the prevalence of dementia among older adults in the United States changed between 2000 and 2012?
In this observational cohort study of more than 21 000 US adults 65 years or older from the nationally representative Health and Retirement Study, dementia prevalence declined significantly, from 11.6% in 2000 to 8.8% in 2012.
Population brain health seemed to improve between 2000 and 2012; increasing educational attainment and better control of cardiovascular risk factors may have contributed to the improvement, but the full set of social, behavioral, and medical factors contributing to the improvement is still uncertain.
The aging of the US population is expected to lead to a large increase in the number of adults with dementia, but some recent studies in the United States and other high-income countries suggest that the age-specific risk of dementia may have declined over the past 25 years. Clarifying current and future population trends in dementia prevalence and risk has important implications for patients, families, and government programs.
To compare the prevalence of dementia in the United States in 2000 and 2012.
Design, Setting, and Participants
We used data from the Health and Retirement Study (HRS), a nationally representative, population-based longitudinal survey of individuals in the United States 65 years or older from the 2000 (n = 10 546) and 2012 (n = 10 511) waves of the HRS.
Main Outcomes and Measures
Dementia was identified in each year using HRS cognitive measures and validated methods for classifying self-respondents, as well as those represented by a proxy. Logistic regression was used to identify socioeconomic and health variables associated with change in dementia prevalence between 2000 and 2012.
The study cohorts had an average age of 75.0 years (95% CI, 74.8-75.2 years) in 2000 and 74.8 years (95% CI, 74.5-75.1 years) in 2012 (P = .24); 58.4% (95% CI, 57.3%-59.4%) of the 2000 cohort was female compared with 56.3% (95% CI, 55.5%-57.0%) of the 2012 cohort (P < .001). Dementia prevalence among those 65 years or older decreased from 11.6% (95% CI, 10.7%-12.7%) in 2000 to 8.8% (95% CI, 8.2%-9.4%) (8.6% with age- and sex-standardization) in 2012 (P < .001). More years of education was associated with a lower risk for dementia, and average years of education increased significantly (from 11.8 years [95% CI, 11.6-11.9 years] to 12.7 years [95% CI, 12.6-12.9 years]; P < .001) between 2000 and 2012. The decline in dementia prevalence occurred even though there was a significant age- and sex-adjusted increase between years in the cardiovascular risk profile (eg, prevalence of hypertension, diabetes, and obesity) among older US adults.
Conclusions and Relevance
The prevalence of dementia in the United States declined significantly between 2000 and 2012. An increase in educational attainment was associated with some of the decline in dementia prevalence, but the full set of social, behavioral, and medical factors contributing to the decline is still uncertain. Continued monitoring of trends in dementia incidence and prevalence will be important for better gauging the full future societal impact of dementia as the number of older adults increases in the decades ahead.
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Corresponding Author: Kenneth M. Langa, MD, PhD, Division of General Medicine, University of Michigan, 2800 Plymouth Rd, Building 16, Room 430W, Ann Arbor, MI 48109-2800 (firstname.lastname@example.org).
Accepted for Publication: September 6, 2016.
Published Online: November 21, 2016. doi:10.1001/jamainternmed.2016.6807
Author Contributions: Dr Langa and Mr Kabeto had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Concept and design: Langa, Larson, Faul, Levine, Kabeto, Weir.
Acquisition, analysis, or interpretation of data: Langa, Larson, Crimmins, Faul, Kabeto, Weir.
Drafting of the manuscript: Langa, Kabeto.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Langa, Crimmins, Faul, Kabeto, Weir.
Administrative, technical, or material support: Larson, Faul, Levine, Weir.
Study supervision: Langa, Faul.
Conflict of Interest Disclosures: None reported.
Funding/Support: This work was supported by cooperative agreement U01 AG009740 (Dr Weir) from the National Institute on Aging (NIA), National Institutes of Health. Additional support was provided by grants K23 AG040278 (Dr Levine), P30 AG053760 (Dr Langa), and P30 AG024824 (Dr Langa) from the NIA. The Health and Retirement Study is performed at the Institute for Social Research, University of Michigan, Ann Arbor.
Role of the Funder/Sponsor: Representatives of the NIA reviewed the manuscript but were not directly involved in the collection, management, analysis, or interpretation of the data, or the decision to submit the manuscript for publication.
Disclaimer: The content of this article is solely the responsibility of the authors and does not necessarily represent the official views of the NIA or the Department of Veterans Affairs.
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