Prevalence of Dementia in the United States: The Aging, Demographics, and Memory Study

TLDR

The study estimates the national prevalence of Alzheimer’s disease and other dementias among adults aged 71 and older using a representative sample from the Health and Retirement Study. An expert consensus panel classified participants into normal cognition, mild cognitive impairment, or dementia, and sampling weights from the HRS were applied to estimate prevalence by age and gender. The weighted analysis found a 13.9 % dementia prevalence (≈3.4 million people) and 9.7 % Alzheimer’s prevalence (≈2.4 million people) among those 71+, with rates rising from 5.0 % at ages 71–79 to 37.4 % at 90+.

Abstract

To estimate the prevalence of Alzheimer's disease (AD) and other dementias in the USA using a nationally representative sample.The Aging, Demographics, and Memory Study sample was composed of 856 individuals aged 71 years and older from the nationally representative Health and Retirement Study (HRS) who were evaluated for dementia using a comprehensive in-home assessment. An expert consensus panel used this information to assign a diagnosis of normal cognition, cognitive impairment but not demented, or dementia (and dementia subtype). Using sampling weights derived from the HRS, we estimated the national prevalence of dementia, AD and vascular dementia by age and gender.The prevalence of dementia among individuals aged 71 and older was 13.9%, comprising about 3.4 million individuals in the USA in 2002. The corresponding values for AD were 9.7% and 2.4 million individuals. Dementia prevalence increased with age, from 5.0% of those aged 71-79 years to 37.4% of those aged 90 and older.Dementia prevalence estimates from this first nationally representative population-based study of dementia in the USA to include subjects from all regions of the country can provide essential information for effective planning for the impending healthcare needs of the large and increasing number of individuals at risk for dementia as our population ages.