Social determinants of health but not global genetic ancestry predict dementia prevalence in Latin America

Abstract

Introduction: Leveraging the nonmonolithic structure of Latin America, which represents a large variability in social determinants of health (SDoH) and high levels of genetic admixture, we aim to evaluate the relative contributions of SDoH and genetic ancestry in predicting dementia prevalence in Latin American populations.

Methods: Community-dwelling participants aged 65 and older (N = 3808) from Cuba, Dominican Republic, Mexico, and Peru completed the 10/66 protocol assessments. Dementia was diagnosed using the cross-culturally validated 10/66 algorithm. Multivariate linear regression models adjusted for SDoH were used in the main analysis. This study used cross-sectional data from the 1066 population-based study.

Results: Individuals with higher proportions of Native American (>70%) and African American (>70%) ancestry were more likely to exhibit factors contributing to worse SDoH, such as lower educational levels (p < 0.001), lower socioeconomic status (p < 0.001), and higher frequency of vascular risk factors (p < 0.001). After adjusting for measures of SDoH, there was no association between ancestry proportion and dementia probability, and ancestry proportions no longer significantly accounted for the variance in cognitive performance (African predominant p = 0.31 [-0.19, 0.59] and Native predominant p = 0.74 [-0.24, 0.33]).

Discussion: The findings suggest that social and environmental factors play a more crucial role than genetic ancestry in predicting dementia prevalence in Latin American populations. This underscores the need for public health strategies and policies that address these social determinants to effectively reduce dementia risk in these communities.

Highlights: Countries in Latin America express a large variability in social determinants of health and levels of admixture. After adjustment for downstream societal factors linked to SDoH, genetic ancestry shows no link to dementia. Population ancestry profiles alone do not influence cognitive performance. SDoH are key drivers of racial disparities in dementia and cognitive performance.

Keywords: Latinos; ancestry; dementia; prevalence; risk factors; social determinants of health.

FIGURE 1

Genetic ancestry in Latin American populations. Legend: The figure depicts ancestry contributions of putative ancestral source populations in four admixed Latin American populations. (A) Admixture plots showing the fractions of African, Native American and European ancestry for all countries combined. (B) Admixture plots showing the fractions of African, Native American, and European ancestry among admixed individuals for each country. Each individual is represented as a column with the admixture fractions color‐coded as shown in the legend. (C) Triangle plots showing the relative ancestry contributions – African, European, Native American – to admixed individuals from four Latin American populations. (D) Pie charts showing the average ancestry values for each population next to their geographic location

FIGURE 2

Dementia probability by age according to genetic ancestry. Legend: Model 1 (nonadjusted base model). Model 2 (adjusted by gender and CDR). Model 3 (adjusted by gender, CDR, education level, social‐economic status (assets)). Model 4 (adjusted by gender, CDR, education level, socioeconomic status (assets), country, rural area, and multimorbidity). CDR, Clinical Dementia Rating® scale. Others: refer to the Admixed Ancestry group, which includes participants for whom no single genetic ancestry (African, European, or Native American) exceeds 70%.