Trends in inequalities in the prevalence of dementia in the United States

Abstract

This paper presents estimates of the prevalence of dementia in the United States from 2000 to 2016 by age, sex, race and ethnicity, education, and a measure of lifetime earnings, using data on 21,442 individuals aged 65 y and older and 97,629 person-year observations from a nationally representative survey, the Health and Retirement Study (HRS). The survey includes a range of cognitive tests, and a subsample underwent clinical assessment for dementia. We developed a longitudinal, latent-variable model of cognitive status, which we estimated using the Markov Chain Monte Carlo method. This model provides more accurate estimates of dementia prevalence in population subgroups than do previously used methods on the HRS. The age-adjusted prevalence of dementia decreased from 12.2% in 2000 (95% CI, 11.7 to 12.7%) to 8.5% in 2016 (7.9 to 9.1%) in the 65+ population, a statistically significant decline of 3.7 percentage points or 30.1%. Females are more likely to live with dementia, but the sex difference has narrowed. In the male subsample, we found a reduction in inequalities across education, earnings, and racial and ethnic groups; among females, those inequalities also declined, but less strongly. We observed a substantial increase in the level of education between 2000 and 2016 in the sample. This compositional change can explain, in a statistical sense, about 40% of the reduction in dementia prevalence among men and 20% among women, whereas compositional changes in the older population by age, race and ethnicity, and cardiovascular risk factors mattered less.

Keywords: Alzheimer’s disease; Markov Chain Monte Carlo; longitudinal analysis; racial and ethnic inequalities.

Fig. 1.

Trends in the age-adjusted prevalence of dementia from 2000 to 2016 by sex and age. Sample: HRS, 2000 to 2016, Age 65+. The sample includes 21,442 individuals and 97,629 person-year observations. The dashed lines show 95% confidence intervals. (A) Average prevalence. (B) Prevalence by sex. (C) Prevalence by age for men. (D) Prevalence by age for women.

Fig. 2.

Trends in the age-adjusted prevalence of dementia from 2000 to 2016 by sex, education, Social Security income, race and ethnicity. Sample: HRS, 2000 to 2016, Age 65+. The sample includes 21,442 individuals and 97,629 person-year observations. Non-Hispanic other race not shown due to small sample size, statistics reported in SI Appendix, Table S6. (A) Prevalence by education, men. (B) Prevalence by education, women. (C) Prevalence by Social Security income quartile, men. (D) Prevalence by Social Security income quartile, women. (E) Prevalence by race and ethnicity, men. (F) Prevalence by race and ethnicity, women.