Prevalence of dementia and cognitive impairment no dementia in a large nationally representative sample: The ELSI‐Brazil study

Abstract

AbstractBackgroundApproximately 77% of older adults in Brazil with dementia have not been diagnosed, indicating a major public health issue. Previous dementia epidemiologic studies from Brazil were based on data from one geopolitical region. We aimed to estimate the general and subgroup‐specific (age, education, and sex) prevalence of dementia diagnosis and cognitive impairment no dementia (CIND) using data from 5,249 participants aged 60 years and older from the Brazilian Longitudinal Study of Aging (ELSI‐Brazil), a large nationally representative sample of older adults.MethodParticipants were classified as either: having normal cognitive function, CIND, or dementia based on a combination of the individuals’ cognitive and functional status. A normative subsample provided adjusted regression‐based norms for the cognitive assessment, and a z‐score of ‐1.5 or lower for global cognition was considered to indicate cognitive impairment. We considered functional impairment if the participant reported one or more difficulties in four gender‐independent daily living activities. Participants were classified as having normal cognitive function if there was no cognitive and functional impairment, as CIND if there was only cognitive impairment, and as dementia if there were both cognitive and functional deficits or if the informant scored above 3.4 points in the Informant Questionnaire on Cognitive Decline in the Elderly.ResultWe found a general prevalence of 6.1% (95% CI = 5.1‐7.3) for dementia and 8.6% (95% CI = 7.1‐10.3) for CIND (Table 1). Dementia prevalence ranged from 3.3% (60‐64 years) to 43.0% (≥ 90 years) by age, and from 2.0% (College level or higher) to 17.5% (illiterates) by educational level. Females had a higher prevalence (7.4%) than males (4.4%). CIND prevalence was similar across the age, sex, and education groups.ConclusionThe estimated dementia prevalence is in line with previous epidemiologic studies. Only 0.8% of the ELSI participants self‐reported having a previous diagnosis of dementia, revealing that underdiagnosis is rampant and a common reality. Based on our results, we expect that nearly 1.7 million of the 2015 population, and 2 million of the 2019 population, might have dementia in Brazil.