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Original Investigation
October 24, 2022

Estimating the Prevalence of Dementia and Mild Cognitive Impairment in the US: The 2016 Health and Retirement Study Harmonized Cognitive Assessment Protocol Project

Author Affiliations
  • 1Department of Neurology, Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York
  • 2Department of Psychiatry and Human Behavior, Brown University Warren Alpert Medical School, Providence, Rhode Island
  • 3Department of Neurology, Brown University Warren Alpert Medical School, Providence, Rhode Island
  • 4Institute for Social Research, University of Michigan, Ann Arbor
  • 5Cognitive Health Sciences Research Program and Department of Internal Medicine, University of Michigan Medical School, Ann Arbor
  • 6Veterans Affairs Center for Clinical Management Research, Ann Arbor, Michigan
  • 7Institute for Healthcare Policy and Innovation, University of Michigan, Ann Arbor
  • 8Department of Neurology and Stroke Program, University of Michigan, Ann Arbor
JAMA Neurol. 2022;79(12):1242-1249. doi:10.1001/jamaneurol.2022.3543
Key Points

Question  What was the prevalence of dementia and mild cognitive impairment (MCI) in the US in 2016?

Findings  This nationally representative cross-sectional study found that approximately one-third of 3496 individuals 65 years and older had dementia or MCI. Prevalence rates were similar by sex but varied by age, education, and race and ethnicity.

Meaning  The results suggest there may be disparities in dementia and MCI among Black and Hispanic older adults and people with lower educational attainment.


Importance  Nationally representative data are critical for understanding the causes, costs, and outcomes associated with dementia and mild cognitive impairment (MCI) in the US and can inform policies aimed at reducing the impact of these conditions on patients, families, and public programs. The nationally representative Health and Retirement Study (HRS) is an essential resource for such data, but the HRS substudy providing dementia diagnostic information was fielded more than 20 years ago and more recent data are needed.

Objective  The Harmonized Cognitive Assessment Protocol (HCAP) was developed to update national estimates of the prevalence of MCI and dementia in the US and examine differences by age, race, ethnicity, and sex.

Design, Setting, and Participants  HRS is an ongoing longitudinal nationally representative study of people 51 years and older with staggered entry dates from 1992 to 2022 and follow-up ranging from 4 to 30 years. HCAP is a cross-sectional random sample of individuals in HRS who were 65 years or older in 2016. Of 9972 age-eligible HRS participants, 4425 were randomly selected for HCAP, and 3496 completed a comprehensive neuropsychological test battery and informant interview, none of whom were excluded. Dementia and MCI were classified using an algorithm based on standard diagnostic criteria and comparing test performance to a robust normative sample.

Exposures  Groups were stratified by age, sex, education, race, and ethnicity.

Main Outcomes and Measures  National prevalence estimates using population weights.

Results  The mean (SD) age of the study population sample (N = 3496) was 76.4 (7.6) years, and 2095 participants (60%) were female. There were 551 participants who self-identified as Black and not Hispanic (16%), 382 who self-identified as Hispanic regardless of race (16%), 2483 who self-identified as White and not Hispanic (71%), and 80 who self-identified as another race (2%), including American Indian or Alaska Native, Asian, Native Hawaiian or Pacific Islander, or another self-described race. A total of 393 individuals (10%; 95% CI, 9-11) were classified as having dementia and 804 (22%; 95% CI, 20-24) as having MCI. Every 5-year increase in age was associated with higher risk of dementia (weighted odds ratio [OR], 1.95 per 5-year age difference; 95%, CI, 1.77-2.14) and MCI (OR, 1.17 per 5-year age difference, 95% CI, 1.09-1.26). Each additional year of education was associated with a decrease in risk of dementia (OR, 0.93 per year of school, 95% CI, 0.89-0.97) and MCI (OR, 0.94, 95% CI, 0.91-0.97). Dementia was more common among non-Hispanic Black individuals (OR, 1.81; 95% CI, 1.20-2.75) and MCI in Hispanic individuals (OR, 1.42; 95% CI, 1.03-1.96) compared with non-Hispanic White individuals. Other group comparisons by race and ethnicity were not possible owing to small numbers. No differences in prevalence were found between female individuals and male individuals.

Conclusions and Relevance  Using a comprehensive neuropsychological test battery and large sample, the national prevalence of dementia and MCI in 2016 found in this cross-sectional study was similar to that of other US-based studies, indicating a disproportionate burden of dementia and MCI among older Black and Hispanic adults and those with lower education.

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