BACKGROUND:
Dementia is a major global public health challenge. Although typically associated with older age, recent studies show an increase in early-onset cases (before age 65). While 14 risk factors are well-established for dementia, their association in middle-aged populations remains poorly explored. Therefore, this study aimed to investigate the association between dementia and known risk factors in adults aged 50-64 from the ELSI-Brazil study.

METHODS:
A cross-sectional population-based study using data from the Brazilian Longitudinal Study of Aging (ELSI-Brazil, 2015-2016), a population-based sample of urban and rural residents from the five macro-regions of Brazil. The study included 4,815 participants aged 50-64. Twelve of the fourteen known risk factors were analyzed based on the ELSI database. Bivariate analyses were performed using simple Poisson regression to calculate Prevalence Ratios (PR) with 95% confidence intervals and a 5% significance level. Analyses were conducted in Stata software.

RESULTS:
Among the 4.815 participants, the prevalence of early-onset dementia was 2.19% (n=87). Six risk factors showed statistically significant associations with early-onset dementia: low education (illiteracy: PR: 9.18; 95%CI: 4.97-16.96, p=0.000), physical inactivity (PR: 4.21; 95%CI: 2.53-7.01, p=0.000), social isolation (PR: 1.77; 95%CI: 1.15-2.73, p=0.008), depression (PR: 6.39; 95%CI: 3.44-11.87, p=0.000), hearing loss (PR: 3.55; 95%CI: 2.33-5.41, p=0.000), and vision loss (PR: 3.12; 95%CI: 1.90-5.02, p=0.000). No significant associations were found for smoking, alcohol consumption, diabetes, hypertension, obesity, or high cholesterol.

CONCLUSIONS:
Among the risk factors analyzed, low education/illiteracy, depression, social isolation, physical inactivity, hearing loss, and vision loss were associated with early-onset dementia in adults aged 50-64.