Population attributable fractions of modifiable dementia risk factors for cognitive impairment—the ELSA-Brasil cohort studyResearch in context

Summary: Background: Population attributable fractions (PAF) of modifiable dementia risk factors are rarely estimated in low- and middle-income countries. We aim to estimate the relative risk (RR) for cognitive impairment and calculate the PAF in the Estudo Longitudinal da Saúde do Adulto (ELSA-Bra...

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Main Authors: Raphael Machado Castilhos, Vanessa Bielefeldt Leotti, Natan Feter, Alessandra C. Goulart, André Russowsky Brunoni, Claudia Kimie Suemoto, Luana Giatti, Maria Carmen Viana, Sandhi Maria Barreto, Sheila Alvim, Bruce B. Duncan, Maria Inês Schmidt
Format: Article
Language:English
Published: Elsevier 2025-09-01
Series:The Lancet Regional Health. Americas
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Online Access:http://www.sciencedirect.com/science/article/pii/S2667193X25001942
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Summary:Summary: Background: Population attributable fractions (PAF) of modifiable dementia risk factors are rarely estimated in low- and middle-income countries. We aim to estimate the relative risk (RR) for cognitive impairment and calculate the PAF in the Estudo Longitudinal da Saúde do Adulto (ELSA-Brasil). Methods: We analyzed adults aged 35–74 at the baseline (2008–2010) and wave 3 (2017–2019). We estimated the prevalence of eight modifiable dementia risk factors at baseline: hypertension, physical inactivity, diabetes, depression, obesity, low education, smoking, and excessive alcohol consumption. Cognition was evaluated at baseline and wave 3 using six standardized tests for the Brazilian Portuguese. A global cognitive score from the individual cognitive tests was created using calculated z-scores each test. A global z-score below −1.5 was considered indicative of cognitive impairment. We calculated the RR and PAF for cognitive impairment at wave 3. Findings: We followed 10,058 adults (56.7% women, median age of 50 [IQR: 44–56] years) for 8.1 (0.6) years. The eight-year incidence of cognitive impairment in wave 3 was 5.5% (n = 549). Low education had the largest RR (4.32) followed by hypertension (1.43), diabetes (1.27), and smoking (1.35). Low education had the largest PAF (95% CI), 14.2% (11.2–17.3), followed by hypertension 13% (7–19), diabetes 4.2% (0.7–7.7), and smoking 3.2% (0.45–6). The total PAF for significant risk factors was 34.7% (28.2–41.3). Interpretation: The findings highlight the importance of early-life and midlife prevention strategies in low- and middle-income countries, with a focus on addressing educational and cardiovascular risk factors. Funding: RMC received Alzheimer's Association grant (AARGD-21-846545).
ISSN:2667-193X