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White matter hyperintensities and their impact in brain structure and function in alzheimer’s disease and behavioral variant frontotemporal dementia across Latin America and the United States: a cross-sectional study
(Springer Science and Business Media LLC, 2025-08-12)
Florencia Altschuler
;
Verónica Canziani
;
Matías Fraile-Vázquez
;
Raul Gonzalez-Gomez
;
Hernán Hernández
<jats:title>Abstract</jats:title> <jats:sec> <jats:title>Background</jats:title> <jats:p>White matter hyperintensities (WMHs) are a core manifestation of normal and pathological aging and are potentially linked to geographical differences in social and physical exposomes. Previous studies have not examined the impact of WMHs burden on neurodegeneration and cognition in healthy controls (HCs) and patients with Alzheimer’s disease (AD) and behavioral variant frontotemporal dementia (bvFTD) across geographic regions. This study addressed this gap by assessing the impact of WMHs burden on participants with and without dementia from Latin America (LA) and the United States (US).</jats:p> </jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>The study comprised 994 participants, including HCs (<jats:italic>n</jats:italic> = 402), AD (<jats:italic>n</jats:italic> = 359), and bvFTD subjects (<jats:italic>n</jats:italic> = 233) from LA and the US. WMHs and their association with grey matter (GM) atrophy, assessed through GM volume and cortical thickness, were evaluated and compared among groups (HCs, AD, and bvFTD) in LA and the US using a voxel-wise brain imaging approach (<jats:italic>p</jats:italic> < 0.05 family-wise error-corrected for multiple comparisons, minimum cluster size = 50 voxels). Multiple regressions analysis were employed to examine geographic differences in WMHs burden, WMHs-GM associations, and the effect of WMHs on cognitive performance, as assessed by the Mini-Mental State examination.</jats:p> </jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>In the LA cohort only, higher WMHs load was associated with greater GM atrophy across all groups (HCs, AD, bvFTD), with a specific neurodegenerative pattern involving orbitofrontal, cingulate, and temporal areas. HCs from LA showed a greater WMHs load than their US counterparts, and this effect was dependent on GM atrophy. Finally, WMHs burden negatively impacted cognitive performance in dementia subjects, with a greater effect observed in bvFTD subjects from the US.</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusion</jats:title> <jats:p>WMHs have a more pronounced impact on neurodegeneration across the LA cohort, with a worse impact on HCs, which also show higher WMHs burden than their US counterparts. This could increase the risk of developing dementia. Moreover, WMHs burden differentially impacts cognition, with a greater negative effect observed in bvFTD subjects from the US. These findings highlight geographic variations in WMHs-related conditions, offering valuable insights for tailored future research.</jats:p> </jats:sec>
2Scopus© Citations 5
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Comprehensive Analysis of Genetic Contributions to Alzheimer’s Disease and Frontotemporal Dementia in Admixed Latin American Populations
(Wiley, 2024-12)
Juliana Acosta‐Uribe
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Stefanie Danielle Pina Escudero
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J. Nicholas Cochran
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Jared W Taylor
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Caroline Warly Solsberg
<jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>Most research initiatives have emerged from high‐income countries (HIC), leaving a gap in understanding the disease’s genetic basis in diverse populations like those in Latin American countries (LAC). ReDLat tackles this gap, focusing on LAC’s unique genetics and socioeconomic factors to identify specific Alzheimer’s Disease (AD) and Frontotemporal Dementia (FTD) risk factors in Mexico, Colombia, Peru, Chile, Argentina, and Brazil.</jats:p></jats:sec><jats:sec><jats:title>Method</jats:title><jats:p>We employed a comprehensive genetic analysis approach, integrating Whole Genome Sequencing (WGS), Exome Sequencing, and SNP arrays to understand the cohort’s unique genetic architecture. We conducted ancestry analysis and searched for disease‐causing variants with mendelian inheritance, genome‐wide association studies (GWAS), rare variant enrichment, and evaluation of Polygenic Risk Scores (PRS).</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>We recruited and genotyped an initial cohort of 1046 participants with AD, 423 with FTD, and 855 healthy controls (HC) between 2020 and 2023. Analysis is ongoing, and we expect to sequence ∼600 additional samples in the coming months. Ancestry analysis revealed tri‐continental admixture, except for Brazil, which showed an additional Asian component (Figure 1). Top candidate gene rare variant enrichment associations (SKAT p < 0.05) were <jats:italic>TREM2</jats:italic> for FTD and <jats:italic>ABCA7</jats:italic> and <jats:italic>ABCA1</jats:italic> for AD. GWAS identified a robust association with the <jats:italic>APOE</jats:italic> locus on chromosome 19 in AD vs. HC.. We tested an AD PRS developed in European populations by Bellenguez et al (2020). on our cohort using 83 single‐nucleotide polymorphisms.. The PRS modestly distinguishes between all patients and HC (p = 2.4 × 10^‐12), AD vs. HC (p = 2.2 × 10^‐12), and even FTD vs. HC (p = 4.3 × 10^‐5), albeit with modest separation between groups, as expected for its application in a genetically admixed population.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>Our findings represent a pivotal step in understanding the genetic landscape of AD and FTD in admixed populations. They underscore the importance of including diverse populations in genetic research, paving the way for future studies. These findings have the potential to inform more personalized approaches to the diagnosis and treatment of neurodegenerative diseases in diverse global populations, as well as identify novel targets for therapeutic development.</jats:p></jats:sec>
3
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The first genome‐wide association study in the Argentinian and Chilean populations identifies shared genetics with Europeans in Alzheimer's disease
(2023)
Maria Carolina Dalmasso
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Itziar de Rojas
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Natividad Olivar
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Carolina Muchnik
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Bárbara Angel
<jats:title>Abstract</jats:title><jats:sec><jats:title>INTRODUCTION</jats:title><jats:p>Genome‐wide association studies (GWAS) are fundamental for identifying loci associated with diseases. However, they require replication in other ethnicities.</jats:p></jats:sec><jats:sec><jats:title>METHODS</jats:title><jats:p>We performed GWAS on sporadic Alzheimer's disease (AD) including 539 patients and 854 controls from Argentina and Chile. We combined our results with those from the European Alzheimer and Dementia Biobank (EADB) in a meta‐analysis and tested their genetic risk score (GRS) performance in this admixed population.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>We detected apolipoprotein E ε4 as the single genome‐wide significant signal (odds ratio = 2.93 [2.37–3.63], <jats:italic>P</jats:italic> = 2.6 × 10<jats:sup>−23</jats:sup>). The meta‐analysis with EADB summary statistics revealed four new loci reaching GWAS significance. Functional annotations of these loci implicated endosome/lysosomal function. Finally, the AD‐GRS presented a similar performance in these populations, despite the score diminished when the Native American ancestry rose.</jats:p></jats:sec><jats:sec><jats:title>DISCUSSION</jats:title><jats:p>We report the first GWAS on AD in a population from South America. It shows shared genetics modulating AD risk between the European and these admixed populations.</jats:p></jats:sec><jats:sec><jats:title>Highlights</jats:title><jats:p><jats:list list-type="bullet"> <jats:list-item><jats:p>This is the first genome‐wide association study on Alzheimer's disease (AD) in a population sample from Argentina and Chile.</jats:p></jats:list-item> <jats:list-item><jats:p>Trans‐ethnic meta‐analysis reveals four new loci involving lysosomal function in AD.</jats:p></jats:list-item> <jats:list-item><jats:p>This is the first independent replication for <jats:italic>TREM2L</jats:italic>, <jats:italic>IGH‐gene‐cluster</jats:italic>, and <jats:italic>ADAM17</jats:italic> loci.</jats:p></jats:list-item> <jats:list-item><jats:p>A genetic risk score (GRS) developed in Europeans performed well in this population.</jats:p></jats:list-item> <jats:list-item><jats:p>The higher the Native American ancestry the lower the GRS values.</jats:p></jats:list-item> </jats:list></jats:p></jats:sec>
Scopus© Citations 3 1
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The Multi-Partner Consortium to Expand Dementia Research in Latin America (ReDLat): Driving Multicentric Research and Implementation Science
(2021)
Agustin Ibanez
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Jennifer S. Yokoyama
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Katherine L. Possin
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Diana Matallana
;
Francisco Lopera
<jats:p>Dementia is becoming increasingly prevalent in Latin America, contrasting with stable or declining rates in North America and Europe. This scenario places unprecedented clinical, social, and economic burden upon patients, families, and health systems. The challenges prove particularly pressing for conditions with highly specific diagnostic and management demands, such as frontotemporal dementia. Here we introduce a research and networking initiative designed to tackle these ensuing hurdles, the Multi-partner consortium to expand dementia research in Latin America (ReDLat). First, we present ReDLat's regional research framework, aimed at identifying the unique genetic, social, and economic factors driving the presentation of frontotemporal dementia and Alzheimer's disease in Latin America relative to the US. We describe ongoing ReDLat studies in various fields and ongoing research extensions. Then, we introduce actions coordinated by ReDLat and the Latin America and Caribbean Consortium on Dementia (LAC-CD) to develop culturally appropriate diagnostic tools, regional visibility and capacity building, diplomatic coordination in local priority areas, and a knowledge-to-action framework toward a regional action plan. Together, these research and networking initiatives will help to establish strong cross-national bonds, support the implementation of regional dementia plans, enhance health systems' infrastructure, and increase translational research collaborations across the continent.</jats:p>
Scopus© Citations 53 9

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