👤 Renaud La Joie

Sex and racial or ancestral disparities in Alzheimer disease remain incompletely understood; autopsy studies that examine amyloid, tau, and genetic factors are scarce. To test whether neuritic plaque burden and cognitive outcomes differ by sex and whether sex modifies the effects of apolipoprotein E ε4 (APOEε4), informant-reported race, and African ancestry. This was a cross-sectional study using postmortem neuropathological data from the Biobank for Aging Studies, University of São Paulo, São Paulo, Brazil. A total of 2268 autopsies from a population-based, diverse clinicopathological sample were collected between April 2004 and March 2025. Sex, informant-reported race (Black, White), African ancestry proportion, and APOEε4 carrier status. Neuritic plaque burden (Consortium to Establish a Registry for Alzheimer's Disease [CERAD] score), and cognitive function (Clinical Dementia Rating-Sum of Boxes [CDR-SB]). Ordinal logistic regression examined association of sex with CERAD scores and 2- and 3-way interactions among sex, race, ancestry, and APOEε4; adjusting for age, education, vascular factors, and Braak stages. Linear models related pathology to CDR-SB, adding copathologies. The analysis included 2268 autopsies (median [IQR] age, 74.8 [63.8-83.3] years; 1152 [51% male] and 1116 [49%] female; 802 [35%] Black and 1466 [65%] White; other race groups not included owing to small numbers); female individuals were older than male individuals and more likely to exhibit cognitive impairment (CDR global score ≥0.5). Female individuals had higher plaque burden than male individuals (unadjusted odds ratio [OR], 1.97; 95% CI, 1.67-2.29; P < .001), and this association remained significant in adjusted models for sociodemographic and vascular factors and APOEε4 status (adjusted OR, 1.65; 95% CI, 1.33-2.20; P < .001). APOEε4 carriers of both sexes had an approximately 4-fold greater odds of plaques. Significant 2-way interactions were found between sex, APOEε4 status, race, and ancestry on CERAD scores. Black noncarriers (OR, 0.47; 95% CI, 0.34-0.67) and noncarriers of African ancestry (OR, 0.57; 95% CI, 0.43-0.76) were least likely to have high plaque burden, whereas this protection was weakened in ε4 carriers. No significant 3-way interaction was detected. Among individuals with a CERAD score of 2 or higher, female individuals were more likely than male individuals to reach Braak stage V-VI than male individuals (probability ratio, 1.25; 95% CI, 1.13-1.38; P = .002). Adding Braak stage to multivariable models attenuated the female-male difference in plaques and interaction of sex and plaque on CDR-SB was no longer significant. The findings indicate that female sex, APOEε4, and both race and African ancestry were jointly associated with amyloid in this study population. Excess amyloid among women may partly explain their greater tau burden and steeper cognitive decline. These findings highlight the importance of incorporating sex, race, and ancestry into biomarker thresholds, risk stratification, and the design of preventive or disease-modifying trials for Alzheimer disease. Show less

The genetic basis of sporadic early-onset Alzheimer's disease (EOAD) remains largely unknown, prompting evaluation of late-onset Alzheimer's disease (LOAD) polygenic risk in EOAD. A LOAD polygenic score (PGS) was calculated in the Longitudinal Early-onset Alzheimer's Disease Study (LEADS) and Alzheimer's Disease Neuroimaging Initiative (ADNI) study and tested for associations with AD risk, cognitive performance, and imaging and fluid biomarkers. Though PGS was elevated in LOAD and EOAD, it was not a significant predictor of EOAD adjusting for APOE ε4 carrier status and was not associated with age of EOAD onset (p = 0.106) or with cognitive performance (p = 0.417). In LEADS, greater LOAD PGS was associated with differences in neuroimaging and fluid biomarkers, including elevated synaptosomal-associated protein 25 (SNAP-25) (p = 2.3 × 10 While LOAD polygenic risk contributed minimally to EOAD onset and cognitive dysfunction, PGS association with fluid biomarkers in LEADS suggests a role for LOAD polygenic risk in EOAD pathophysiology. LOAD PGSs were elevated in both LOAD and EOAD compared to controls; however, LOAD PGS did not significantly predict EOAD risk, age at onset, or cognitive performance independent of APOE ε4 in the LEADS. Higher LOAD PGS was associated with lower amyloid PET Centiloids (less brain amyloid deposition) as well as lower CSF biomarker Aβ42 in LEADS (proxy marker suggesting higher brain amyloid deposition) in LEADS; these contradictory findings support the need for larger studies to further investigate whether LOAD PGS is associated with increased amyloid deposition in EOAD. Higher LOAD PGS was also associated with higher levels of CSF synaptosomal-associated protein 25 (SNAP-25), a key component of the SNARE complex, suggesting that LOAD genetic factors may contribute to dysregulation of synaptic transmission and/or pathological protein aggregation in EOAD. Show less

The spatial progression of longitudinal tau pathology has been inferred using cross-sectional data, but longitudinal voxel-wise analyses allow these patterns to be established without inference. We pooled 1426 flortaucipir (FTP) positron emission tomography (PET) scans from 583 participants across the aging and Alzheimer's disease (AD) spectrum from four studies. Using longitudinal tau-PET slope maps, we examined tau accumulation by clinical group and its associations with participant characteristics, baseline beta-amyloid (Aβ), and tau. Tau accumulation was limited to temporoparietal cortices in unimpaired participants but widespread in patients. Baseline Aβ, entorhinal, and inferior temporal tau predicted progressively more severe tau accumulation patterns. Age, sex, and apolipoprotein E (APOE) ε4 had modest moderating effects. Aβ and early tau interactions showed synergistic effects. Greater tau accumulation was linked to worse follow-up cognition than baseline. While Aβ influences early tau progression, baseline tau drives later progression. These results may guide future trials targeting tau accumulation at different disease stages. Faster tau spread from temporal to frontal lobes was linked to clinical impairment. Global beta-amyloid (Aβ), entorhinal, and inferior temporal gyrus (ITG) tau predicted progressively worse tau accumulation. Age, sex, and apolipoprotein E (APOE) had minimal effects on tau accumulation. Aβ and early tau burden interact synergistically to drive tau accumulation. More severe tau accumulation was linked to worse cognition at follow-up than baseline. Show less