Prevalence of Dementia and Mild Cognitive Impairment in the United States: Findings from the Health and Retirement Study (HRS) Harmonized Cognitive Assessment Protocol (HCAP) Project

Abstract

BackgroundNationally representative data are critical for understanding the causes, costs and consequences of dementia and MCI in the US and can better inform policies aimed at reducing their impact on patients, families, and public programs. Because research on dementia is often based on highly selected samples of older adults who are disproportionately White, college-educated, and high-income, the nationally representative Health and Retirement Study (HRS) has become an essential resource for US population-level information on dementia prevalence and incidence. However, the original HRS substudy providing dementia diagnostic information was fielded more than 20 years ago. We developed the Harmonized Cognitive Assessment Protocol (HCAP) to provide national estimates of the prevalence of MCI and dementia in the US and to examine differences by age, race and ethnicity, and gender.MethodA random sample of 3,496 HRS participants age 65+ completed a comprehensive neuropsychological test battery and a standard informant interview. Dementia and MCI were classified using an algorithm based on standard diagnostic criteria and comparing test performance to a robust normative sample. National prevalence was estimated using population weights.ResultA total of 393 (9.8%) individuals [mean (SD) age, 82.3 (7.4); 243 women (62%) and 150 men (38%)] were classified as having dementia, and 804 (22%) individuals were classified as having MCI [mean (SD) age, 76.8 (7.8) years, 243 women (62%) and 150 men (38%)]. People with dementia and MCI were more likely to be older, had fewer years of school, and were more likely to be non-Hispanic Black or Hispanic than non-Hispanic White. No differences in prevalence were found between women and men.ConclusionUsing a comprehensive, harmonized neuropsychological test battery and large substudy sample to derive national estimates, we found the prevalence of dementia and MCI among people age 65 and older was similar to that of other Western countries. Cognitive impairment is common among older adults, and shows significant patterning along racial, ethnic, and socioeconomic lines. Updated dementia prevalence estimates for the United States from 2016 show that the disproportionate burden of dementia and MCI among Black and Hispanic older adults and people with lower educational attainment persists.