Dementia in Latin America: Paving the way toward a regional action plan.

Across Latin American and Caribbean countries (LACs), the fight against dementia faces pressing challenges, such as heterogeneity, diversity, political instability, and socioeconomic disparities. These can be addressed more effectively in a collaborative setting that fosters open exchange of knowledge. In this work, the Latin American and Caribbean Consortium on Dementia (LAC-CD) proposes an agenda for integration to deliver a Knowledge to Action Framework (KtAF). First, we summarize evidence-based strategies (epidemiology, genetics, biomarkers, clinical trials, nonpharmacological interventions, networking, and translational research) and align them to current global strategies to translate regional knowledge into transformative actions. Then we characterize key sources of complexity (genetic isolates, admixture in populations, environmental factors, and barriers to effective interventions), map them to the above challenges, and provide the basic mosaics of knowledge toward a KtAF. Finally, we describe strategies supporting the knowledge creation stage that underpins the translational impact of KtAF.

Definition of Late Onset Alzheimer's Disease and Anticipation Effect of Genome-Wide Significant Risk Variants: Pilot Study of the APOE e4 Allele.

BACKGROUND/OBJECTIVES: This study aims to investigate the role of apolipoprotein E (APOE) e4 influencing the age at onset (AAO) of Alzheimer's disease (AD). In AD, the AAO of dementia varies from 40 to 90 years. Usually, AD patients who develop symptoms before the age of 65 are considered as early-onset AD (EOAD). However, considering the heterogeneity of the AD onset, the definition of late-onset AD (LOAD) cannot rely on an arbitrary cut-off. Thus, we aim to validate the anticipation effect of the APOE e4 allele in LOAD. Methods/Overview: Firstly, the optimal number of AAO subgroups was determined using MCLUST for 3 AD samples from Italy, Brazil, and from the ADNI consortium. MCLUST selects the best-fitting model based on the Bayesian information criterion (BIC), and the ideal cut-off for separating early onset from late onset in each sample. Then, when the AAO was modeled for each sample, the finite mixture model (FMM) analysis was used to analyze the effect of the APOE e4 in determining the risk for anticipated onset in LOAD. For the Brazilian sample, the ancestry was incorporated as a covariate. The FMM results from the 3 samples were meta-analyzed using METAL. RESULTS: We performed the AAO analysis on the APOE e4 in 474 Italian patients enrolled at the IRCCS Santa Lucia Foundation in Italy, 135 AD from the Outpatients Reference Center for Geriatrics from the Federal University of Minas Gerais in Brazil, and 376 from the ADNI consortium. Using this distribution model, we found that the specific LOAD cut-off was ≥64 for the Italian sample, ≥67 for the ADNI sample, and ≥74 for the Brazilian sample. The APOE e4 showed a significant anticipatory effect specific for LOAD in all 3 samples. The METAL analysis for the anticipatory e4 effect was genome-wide significant when analyzing the LOAD effect size under the fixed model (beta = -8.1; p < 0.0001). However, when analyzing EOAD there was no genome-wide significant anticipation effect (beta = 1.9244; p = 0.0219). CONCLUSIONS: This study showed that the mixture analysis can refine the ideal cut-off for defining LOAD as a homogeneous genetic entity. We also validated the e4 allele anticipatory effect only in LOAD. In summary, the tool developed in this study is a sophisticated statistical pipeline to analyze the AAO in genome-wide association studies of AD, to find new molecular targets as a new line of translational research to foster drug discovery.