Cognitive Resilience in Apolipoprotein ε4 Carrier Women Predicted by Neuron-Derived Extracellular Vesicles.

OBJECTIVE: The Apolipoprotein (APOE) ε4 allele is the strongest genetic risk factor for late-onset Alzheimer's disease (AD); however, many ε4 carriers remain cognitively intact into old age. Leveraging plasma neuron-derived extracellular vesicles (NDEVs), we sought to identify biomarkers of cognitive resilience and their interplay with APOE genotype. METHODS: In this case-control study nested within the Women's Health Initiative (WHI), we analyzed 1130 plasma samples from 676 women in the WHI Memory Study (WHIMS)/Long Life Study (LLS), with APOE ε4 or ε3/ε3 genotypes. At baseline, all participants were cognitively intact and at LLS visit, 13-17 years later, were classified as still cognitively intact (resilient) or having become impaired at age > 80 or ≤ 80 years. We isolated NDEVs using immunoaffinity capture for the neuronal marker L1CAM and quantified AD pathogenic proteins (Aβ(42), total Tau, p181-Tau), insulin signaling (pSer312-IRS-1), TNFR1/NFκB pathway mediators and targets, and mitochondrial Complex V. Linear mixed models assessed group differences, adjusting for NDEV yield, age, and education, with FDR correction. RESULTS: No group differences were found for Aβ(42), Tau proteins, or pS312-IRS-1. Resilient ε4 carriers had higher baseline levels of phosphorylated TNFR1, NFκB, c-Myc, and FADD than ε4 carriers who eventually developed impairment at > 80 or ≤ 80 years. Additionally, resilient ε4 carriers had higher baseline Complex V levels than ε4 carriers impaired at age > 80. INTERPRETATION: Augmented neuronal TNFR1/NFκB signaling and Complex V levels may promote cognitive resilience in ε4 carrier women. Boosting these mechanisms may have preventive and therapeutic potential against cognitive decline in this high-risk population.