Dementia Prevalence in the United States in 2000 and 2012: Estimates Based on a Nationally Representative Study

Abstract

Objectives: Age- and sex-specific rates of dementia are estimated in the U.S. population aged 65 or older in 2000 and 2012 using a large nationally representative dataset, the Health and Retirement Study (HRS), and accounting for mortality selection and specificities of the interview protocol.

Method: A latent cognitive ability model is estimated by maximum simulated likelihood. Prevalence of dementia is identified using HRS cognition measures and the Aging, Demographics and Memory Study (ADAMS), a subset of the HRS (n = 856) with clinical assessment for dementia. Different cognitive measures are collected in self and proxy interviews. From 2006 onward, the HRS collected fewer interviews by proxy. Selection into proxy interviews is modeled as well as survival into the ADAMS sample from the previous HRS interview.

Results: The prevalence of dementia decreased from 12.0% (SE = 0.48%) in 2000 to 10.5% (SE = 0.49%) in 2012 in the 65+ population, a statistically significant decline of 12.6% (p < .01). The percentage change in prevalence was larger among males (16.6% vs 9.5%), and younger individuals.

Discussion: The prevalence of dementia among those 65 or older decreased between 2000 and 2012, although less rapidly than reported in other studies. The difference is primarily due to our modeling selection into proxy interviews.

Figure 1.

5-Year mortality rates by imputed dementia status, HRS 1998–2008, age 65–95, weighted. The publicly available HRS includes the years and months (but not the days) of the interviews and of deaths. 5-Year mortality rates are estimated by investigating if individuals are alive 5 years and 0 months after their HRS interviews. Dementia status is imputed using the cutoff approach of Langa and colleagues (2017), in which individuals represented by a proxy are imputed to have dementia if they scored 6 or higher on an 11-point scale of cognitive problems, and self respondents are imputed to have dementia if they scored 6 or lower on a 27-point scale of working and episodic memory.