Prevalence of Dementia and Cognitive Impairment No Dementia in a Large and Diverse Nationally Representative Sample: The ELSI-Brazil Study

Background Approximately 77% of older adults with dementia in Brazil have not been diagnosed, indicating a major public health issue. Previous epidemiological dementia studies in Brazil were based on data from 1 geopolitical region. Methods We aimed to estimate the general and subgroup-specific (age, education, and sex) prevalence of dementia and cognitive impairment no dementia (CIND) classification using data from 5 249 participants aged 60 years and older from the ELSI-Brazil, a large nationally representative sample. Participants were classified as having normal cognitive function, CIND, or dementia based on a combination of the individual's cognitive and functional status. Results We found a general prevalence of 5.8% (95% CI = 4.7-7.2) for dementia and 8.1% (95% CI = 6.8-9.5) for CIND. Dementia prevalence ranged from 3.2% (60-64 years old) to 42.8% (>= 90 years old) by age, and from 2.1% (college level or higher) to 16.5% (illiterates) by education. Females had a higher dementia prevalence (6.8%) than males (4.6%). CIND prevalence was similar across age, sex, and education. Conclusions The estimated dementia prevalence is lower than that in previous Brazilian epidemiological studies, but is in line with other Latin American studies. Only 1.2% of the ELSI-Brazil participants reported having a previous diagnosis of dementia, revealing that underdiagnosis is rampant and a common reality. Based on our results and national statistics projections, we estimate that in 2019, there were 1 757 480 people aged 60 years and older living with dementia in Brazil and, at least, another 2 271 314 having to deal with some form of cognitive impairment.