Inequities in Dementia Diagnosis: Evidence From the ELSI-Brazil Study

To estimate the national proportion of undiagnosed dementia cases in Brazil, examine its distribution across Brazilian regions sociodemographic subgroups, and identify factors associated with receiving a diagnosis.

We conducted a cross-sectional, population-based analysis using baseline data (2015-2016) from the Brazilian Longitudinal Study of Aging (ELSI-Brazil), a nationally representative survey of community-dwelling adults. Dementia was identified through an established algorithm incorporating cognitive testing and functional impairment, combined with self-reported medical diagnosis of Alzheimer's disease. Underdiagnosis was defined as meeting dementia criteria without a prior medical diagnosis. Sociodemographic, clinical, cognitive, and functional variables were assessed. Survey-weighted logistic regression models estimated factors associated with underdiagnosis.

Among 5249 participants aged ≥ 60 years, 392 met criteria for dementia. Overall, 83.1% (95% CI: 76.5-88.1) had no previous diagnosis. Underdiagnosis was more frequent in poorer regions (90.2%) than in richer regions (76.0%), and higher among illiterate individuals (93.9%). In fully adjusted models, older age (OR = 0.91; 95% CI: 0.85-0.97), more years of education (OR = 0.86; 95% CI: 0.76-0.96), a higher number of chronic conditions (OR = 0.72; 95% CI: 0.54-0.97), and better memory performance (OR = 0.68; 95% CI: 0.56-0.84) were associated with a lower likelihood of underdiagnosis, while living alone was associated with a higher likelihood of underdiagnosis (OR = 3.65 [1.05-12.6]).

About four in five older Brazilians meeting dementia criteria had no prior clinical diagnosis, with marked sociodemographic and regional disparities. Both individual factors-such as age, education, and multimorbidity-and structural inequities across regions influenced diagnostic likelihood. Strengthening early-detection strategies, improved health professional training, and regionally tailored approaches may improve recognition of dementia in Brazil's public health system.