Secular Trends in Dementia and Cognitive Impairment of U.S. Rural and Urban Older Adults

Published in: American Journal of Preventive Medicine [Epub December 2017]. doi: 10.1016/j.amepre.2017.10.021

Posted on RAND.org on December 20, 2017

by Margaret Weden, Regina A. Shih, Mohammed U. Kabeto, Kenneth M Langa

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Research Questions

  1. What is the prevalence of dementia (expressed in terms of relative risk) and cognitive impairment without dementia (CIND) in rural vs. urban U.S. populations?
  2. How did the prevalence change between 2000 and 2010?

Introduction

This is a nationally representative study of rural-urban disparities in the prevalence of probable dementia and cognitive impairment without dementia (CIND).

Methods

Data on non-institutionalized U.S. adults from the 2000 (n=16,386) and 2010 (n=16,311) cross-sections of the Health and Retirement Study were linked to respective Census assessments of the urban composition of residential census tracts. Relative risk ratios (RRR) for rural-urban differentials in dementia and CIND respective to normal cognitive status were assessed using multinomial logistic regression. Analyses were conducted in 2016.

Results

Unadjusted prevalence of dementia and CIND in rural and urban tracts converged so that rural disadvantages in the relative risk of dementia (RRR=1.42, 95% CI=1.10, 1.83) and CIND (RRR=1.35, 95% CI=1.13, 1.61) in 2000 no longer reached statistical significance in 2010. Adjustment for the strong protective role of educational attainment reduced rural disadvantages in 2000 to statistical nonsignificance, whereas adjustment for race/ethnicity resulted in a statistically significant increase in RRRs in 2010. Full adjustment for sociodemographic and health factors revealed persisting rural disadvantages for dementia and CIND in both periods with RRR in 2010 for dementia of 1.79 (95% CI=1.31, 2.43) and for CIND of 1.38 (95% CI=1.14, 1.68).

Conclusions

Larger gains in rural adults' cognitive functioning between 2000 and 2010 that are linked with increased educational attainment demonstrate long-term public health benefits of investment in secondary education. Persistent disadvantages in cognitive functioning among rural adults compared with sociodemographically similar urban peers highlight the importance of public health planning for more rapidly aging rural communities.

Key Findings

  • In 2010, prevalence rates for both conditions were higher in rural areas (80 percent higher relative risk for dementia, and 40 percent higher for CIND), after adjusting for sociodemographic and health factors.
  • From 2000 to 2010, the rural-urban disparity narrowed for both conditions.
  • The most important factor in reducing the rural-urban disparities over the decade was educational attainment.

Recommendations

  • Persistent disadvantages in cognitive functioning among rural adults highlight the importance of public health planning for more rapidly aging rural communities.
  • Gains in rural adults' cognitive functioning between 2000 and 2010 that are linked with educational attainment show the long-term public health benefits of investing in secondary education.

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