The apolipoprotein E (APOE) gene represents the strongest genetic determinant of sporadic Alzheimer's disease (AD), yet its interaction with sex-specific endocrine factors remains poorly understood. L Show more
The apolipoprotein E (APOE) gene represents the strongest genetic determinant of sporadic Alzheimer's disease (AD), yet its interaction with sex-specific endocrine factors remains poorly understood. Lifetime estrogen exposure, estimated through reproductive lifespan, may modulate neurodegenerative risk, but findings are inconsistent. Previous studies have examined reproductive factors and APOE interactions in relation to cognitive outcomes, but dose-dependent effects across all APOE alleles (ε2, ε3, ε4) in clinically diagnosed AD patients remain underexplored. This study investigates the joint effects of reproductive lifespan, age at natural menopause (ANM), and APOE genotype on AD risk in females. A total of 396 female participants (103 with AD, 293 cognitively healthy controls) were retrospectively analyzed. Demographic, clinical, and reproductive data were extracted from medical records. APOE genotyping was performed by sequencing rs429358 and rs7412 polymorphisms. Logistic regression models tested associations between ANM, reproductive lifespan, and AD diagnosis, adjusting for education, body mass index (BMI), smoking, diabetes, hypertension, and number of children. Moderation analyses assessed the interaction between reproductive variables and APOE ε2, ε3, and ε4 alleles, and were followed by simple slope analyses to clarify the direction of significant effects. AD females exhibited later ANM (50.3 ± 4.4 vs. 48.3 ± 6.2 years; This work provides novel evidence that extended ovarian function is associated with increased AD vulnerability in females, particularly among APOE ε4 carriers. These findings highlight a dose-dependent, genotype-specific interaction between reproductive aging and neurodegeneration, suggesting APOE as a molecular bridge linking estrogenic exposure and AD risk. Show less