The effect of APOEƐ4 on neurocognitive decline is accentuated by female sex and menopause: Identification of mitigating interventions

Abstract

AbstractBackgroundTwo thirds of those living with AD are female. Age‐standardised AD prevalence is consistently higher at all ages over 70 years in women versus men. The aetiology of the accelerated neurophysiological decline in females is poorly understood. Here we investigate the independent and interactive impact of APOE4 carrier status and menopause.MethodTargeted replacement (APOE3‐TR and APOE4‐TR) rodent models and human cohort studies (European Prevention of Alzheimer’s Dementia (EPAD) and UK Biobank (UKB)) were used to investigate the impact of APOE4, menopause and hormone replacement therapy (HRT) on cognition, brain volumes (assessed by MRI), omega‐3 fatty acid status and synaptic function. In rodents, menopause is elicited by the administration of 4‐vinylcyclohexene diepoxide (VCD), which induces a human‐like “perimenopausal” phenotype, whilst maintaining ovarian tissue integrity.ResultsIn EPAD, using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) test battery, HRT use in APOE4 only was associated with higher overall cognition and (delayed) memory scores and larger entorhinal and amygdala volumes in APOE4 only. Earlier HRT introduction was associated with larger hippocampal volumes. In UKB, HRT use was associated with improved memory in APOE4/E4. In mice, VCD administration reduced recognition memory, brain docosahexaenoic acid (DHA, omega‐3 fatty acid) levels, and altered synaptic plasticity biomarkers in APOE4‐TR animals, which was mitigated by DHA supplementation (1).ConclusionAn increased penetrance of the APOE4 genotype during the menopausal transition is likely to contribute to the higher incident AD in females, and in APOE4 females versus non‐carriers. HRT and DHA intervention during the menopausal transition, as a critical window of opportunity, may represent effective strategies to support cognitive health into older age in this ‘at‐risk’ (APOE4 female) group, which typically represent 12% of Caucasian populations compared and 33‐50% of AD.1. Pontifex MG et al., FASEB J. 2021 May;35(5):e21583