👤 Charles DeCarli

Apolipoprotein E (APOE) alleles are well-established genetic risk factors for Alzheimer's disease (AD), but their effects on AD biomarkers (amyloid beta [Aβ]42/40, phosphorylated tau [p-tau]181, neurofilament light chain [NfL], and glial fibrillary acidic protein [GFAP]) may vary across populations due to ancestry-, age-, and sex-related differences. We hypothesized that these effects vary across Hispanic/Latino background groups with distinct ancestral admixture. We analyzed ε2 and ε4 allele associations with AD biomarkers using survey-weighted linear regression models, adjusting for demographic covariates. Secondary analyses examined genetic analysis group- and ancestry-specific effects. ε4 was associated with lower Aβ42/40 and higher p-tau181and GFAP levels, but not with NfL, suggesting its role in Aβ and tau deposition and neuroinflammation. ε4 associations were stronger in those with higher European and lower African ancestry. These findings expand on prior studies suggesting that genetic ancestry modifies APOE-associated AD risk in Hispanic/Latino populations and highlight the importance of capturing ancestry-based heterogeneity in AD biomarker research. Show less

Machine learning enables scalable quantification of neuropathology, offering deeper phenotyping of Alzheimer's disease (AD). In this validation study, we quantified amyloid-beta (Aβ) deposits, evaluating multiple brain regions across institutions, and evaluated associations with clinical, demographic, and genetic factors in persons pathologically diagnosed with AD. All linear models were adjusted for sex, age of death, ethnicity, and center. We analyzed densities (#/mm2) of cored plaques, diffuse plaques, and cerebral amyloid angiopathy (CAA) in 273 individuals from 3 Alzheimer's Disease Research Centers. Formalin-fixed paraffin-embedded sections of frontal, temporal, and parietal cortices were immunostained and digitized, generating 799 whole-slide images (WSIs). Following log transformation, mixed-effects modeling revealed the parietal cortex had the highest cored plaque densities (P < .001); the temporal cortex had the highest diffuse plaque (P < .001); CAA showed no regional differences. Wilcoxon rank-sum test, and covariates adjusted linear models showed ApoE ε4- status was associated with higher cored plaque densities in the temporal lobe (P = .04). ApoE ε4+ status was associated with diffuse plaques in the temporal lobe (P = .001), and CAA in the frontal lobe (P = .004). These findings provide further validation and provide exploratory associations advancing deeper phenotyping of AD. Show less

The purpose of this study was to estimate the prevalence and number of cerebral microbleeds (CMBs) in a Hispanic and Latino cohort from various self-identified backgrounds and test associations with age, vascular risk factors, APOE (apolipoprotein E), and cognitive function. The 3T brain magnetic resonance imaging exams were obtained on SOL-INCA-MRI (Study of Latinos-Investigation of Neurocognitive Aging-MRI) magnetic resonance imaging study participants, a community-based study. CMB number was counted and categorized as: (1) any CMB, (2) lobar only, (3) deep only, (4) mixed, (5) deep+mixed, and (6) lobar+mixed. We examined whether prevalence of CMBs varied by age, sex, education, Hispanic background, cardiovascular risk factors (hypertension, diabetes, Framingham Risk Score), APOE genotype, and cognition. A total of 2455 participants were included who were 63.0±8.4 years of age, 67.9% women, and 62.2% high school education or higher. CMBs prevalence was 11.7% (8.3% lobar only, 2.0% deep only, 1.4% mixed locations). After adjusting for age, sex, and education, a high Framingham Risk Score was associated with the presence of CMBs of all types, except lobar only. Prevalent stroke/transient ischemic attack was associated with higher likelihood of deep-only CMBs. For participants with cognitive impairment, the adjusted prevalence of mixed CMBs (2.2% versus 1.1%, High vascular risk scores, self-reported history of stroke/transient ischemic attack, and cognitive status were associated with a higher likelihood of CMBs, especially in deep regions. Show less

Blood-based biomarkers hold promise as a minimally invasive tool for identifying early signs of Alzheimer's disease pathology and neurodegeneration. We investigated associations between plasma biomarkers of amyloid-beta, tau, neuroaxonal injury, and glial activation with cognitive performance among community-dwelling Hispanic/Latino adults in the United States. We analyzed cross-sectional data from 5730 adults aged 50 years and older (unweighted; mean [SD], 63.5 [8.2] years) in the Study of Latinos-Investigation of Neurocognitive Aging (SOL-INCA; 2016-2018). Plasma concentrations of amyloid-beta (Aβ Here we show higher ln(pTau-181) and ln(NfL) are associated with lower global cognitive performance (b Plasma biomarkers related to Alzheimer's disease pathophysiology and broader neurodegenerative processes are associated with cognitive performance among Hispanic/Latino adults. These findings highlight the potential utility of blood-based biomarkers for identifying early cognitive vulnerability in this population. Show less