Public Health.

Background: Dementia prevalence in Latin America is higher in rural than urban areas. This discrepancy may be explained by inequities over the lifespan in access to health and educational services. However, there is no evidence of potential adverse long-standing effects of living in rural areas during childhood in current urban adults. This work investigates whether being born in rural areas (Rurality) increases exposure to dementia risk factors in adulthood among individuals who have emigrated to urban centers early in life.

Method: 130 individuals aged 40+ years were screened across 11 schools offering a late-life educational program in Belo Horizonte. Participants underwent a comprehensive neuropsychological evaluation, sociodemographic interviews, literacy assessment, and serum neurofilament light chain (sNfL) exam. Participants were classified as originally from the metropolitan region (BH), or born in countryside regions (CS). The groups were compared in terms of sociodemographic features, cognitive performance, Dementia risk factors, and neurodegeneration.

Result: 108 met the inclusion criteria. Mean age was 58 (9.7) years, 71% women, and 90% non-whites. CS (80% of the sample) and BH had similar sociodemographic characteristics. Cognitive performance was not significantly different. Concerning dementia risk factors, there was no difference in the frequency of sedentarism and depression (X², p = 0.38, for both), and for self-reported hypertension, diabetes, dyslipidemia, smoking, alcohol consumption, hearing impairment, and severe head trauma. (X², p > 0.3 for all). Participants in the BH group were 4 times more likely to attend formal school during life, (p = 0.017), and had more years of schooling (p = 0.001). Education in childhood was positively associated with literacy level in adulthood (p = 0.024). Literacy level, but not education, was associated with global cognition, Executive functioning, and sNfL levels (p-value = 0.003, 0.001, and 0.032).

Conclusion: Decreased educational attainment in childhood was the main difference between the groups. This difference might be perpetuated over their lifespan in urban areas by a persistent disparity in basic literacy level. Our study suggests that low literacy/illiteracy might be an underlying mechanism linking rural origins to increased dementia risk, even among Brazilians currently in urban areas.