Study Background and Disease Burden
Dementia represents a growing global health challenge, with particularly profound implications in low- and middle-income countries (LMICs) like Brazil. The increasing aging population in Brazil amplifies the burden of dementia, straining both healthcare resources and family caregivers. The 2024 update of The Lancet Commission on dementia prevention, intervention, and care expanded the list of modifiable risk factors to 14, reflecting new evidence linking lifestyle and health interventions to dementia risk reduction. Prior estimates of preventable dementia in LMICs were limited, and this new study by Suemoto et al. provides the first population attributable fraction (PAF) specifically for Brazil, shedding light on how targeted public health strategies could reduce dementia incidence significantly in this context.
Study Design
This investigation utilized data from 9949 community-dwelling participants aged 50 years or older enrolled in the nationally representative second wave of the Brazilian Longitudinal Study of Aging (ELSI-Brazil) conducted between 2019 and 2021. The cohort selection ensured demographic diversity across sex, race, and regional macrosocial divisions within Brazil. Researchers assessed the prevalence of 14 modifiable dementia risk factors identified by the 2024 Lancet Commission. These factors included less education, untreated visual loss, midlife depression, and others encompassing lifestyle, cardiovascular, and psychosocial dimensions.
Principal component analysis was applied to evaluate communalities among risk factors, thus preventing double counting of overlapping risks. Subsequently, population attributable fractions for each risk factor—and collectively—were computed using relative risk estimates from the Lancet report, deploying stratified analyses by sex, race, and geographical macro regions to elucidate disparities in preventable dementia burden.
Key Findings
The overall combined population attributable fraction for the 14 modifiable risk factors was estimated at 59.5% (95% confidence interval [CI]: 58.5%–60.5%), indicating that nearly 6 out of 10 dementia cases in Brazil could theoretically be prevented by eliminating these risks.
Among individual factors, the largest contributors to preventable dementia cases were:
– Less education: 9.5% (95% CI: 8.9%–10.1%)
– Untreated visual loss: 9.2% (95% CI: 8.6%–9.8%)
– Midlife depression: 6.3% (95% CI: 5.8%–6.8%)
These findings underscore the significance of socio-educational and mental health interventions alongside sensory health care in dementia prevention. The data revealed no substantial variation in overall PAF across different races or Brazilian macro regions, suggesting a broadly uniform distribution of preventable risk. However, the estimated PAF was higher in women (61.1%, 95% CI: 59.9%–62.4%) than men (58.2%, 95% CI: 56.7%–59.8%), potentially reflecting gender differences in risk factor prevalence or vulnerability.
Expert Commentary
This robust study leverages a nationally representative dataset enabling the first precise LMIC estimate of preventable dementia fractions. By applying updated relative risks and accounting for overlapping factors through principal component analysis, it offers a methodologically sound and clinically relevant quantification of dementia prevention potential in Brazil.
It is notable that education remains the highest attributable risk factor, reaffirming lifelong education’s critical role in brain health and cognitive reserve. Untreated visual loss as a leading preventable contributor highlights the underappreciated role of sensory impairments in dementia etiology and their amenability to relatively straightforward interventions like cataract surgery or corrective lenses.
The finding that nearly 60% of dementia could be averted aligns with global estimates but emphasizes the disproportionately high impact in an LMIC context, where social determinants of health and access disparities are marked. The observed sex differences warrant tailored prevention strategies.
Limitations include the cross-sectional nature of risk factor prevalence data and reliance on relative risks derived from global meta-analyses rather than Brazilian-specific etiological studies. Future work integrating longitudinal data and exploring mechanistic pathways in LMIC populations will enhance precision.
Conclusion
Suemoto and colleagues’ study provides compelling evidence that addressing 14 modifiable risk factors could prevent almost 60% of dementia cases in Brazil. Integrative public health policies targeting educational access, visual impairment treatment, mental health, and other risk factors are urgently needed to reduce Brazil’s dementia burden. These findings offer a clear roadmap for both prevention and prioritization of healthcare resources, with implications for other LMICs with similar demographic and epidemiological profiles. Continued investment in dementia prevention, early intervention, and health equity will be essential to mitigate the expected rise in dementia-related disability and costs in Brazil and beyond.
References
1. Suemoto CK, Borelli WV, Calandri IL, Bertola L, Castilhos RM, Caramelli P, et al. The potential for dementia prevention in Brazil: a population attributable fraction calculation for 14 modifiable risk factors. Lancet Reg Health Am. 2025 Aug 7;49:101209. doi:10.1016/j.lana.2025.101209. PMID: 40823285; PMCID: PMC12355584.
2. Livingston G, Huntley J, Sommerlad A, Ames D, Ballard C, Banerjee S, et al. Dementia prevention, intervention, and care: 2020 report of the Lancet Commission. Lancet. 2020 Aug 8;396(10248):413-446.
3. World Health Organization. Risk reduction of cognitive decline and dementia: WHO guidelines. 2019.
