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Background: This study examined the impact of apolipoprotein ɛ4 (APOEɛ4) allele frequency and sex on the phenotype of Alzheimer’s disease (AD). Methods: This post hoc study evaluated the baseline characteristics, cerebrospinal fluid (CSF) and neuroimaging biomarkers, and cognition scores collected from 45 patients aged 50–74 years with CSF-biomarker-confirmed mild cognitive impairment or mild dementia due to AD from clinical trial NCT03186989. Results: A phenotypic spectrum was observed from a predominant amyloid and limbic–amnestic phenotype in male APOEɛ4 homozygotes to a predominantly tau, limbic-sparing, and multidomain cognitive impairment phenotype in female APOEɛ4 noncarriers. Amyloid pathology was inversely correlated with tau pathophysiology, glial activation, and synaptic injury, with the strongest associations observed in male APOEɛ4 carriers. Tau pathophysiology was correlated with glial activation, synaptic injury, and neuroaxonal damage, with the strongest correlation observed in female APOEɛ4 noncarriers. Conclusions: These data support the hypothesis that functional glial activation is influenced by apoE isoform and sex and might explain much of the biological and clinical heterogeneity in early clinical AD in those aged 50–74 years. Conclusions are limited because of the retrospective nature and small sample size. Trial Registration: Clinical Trial NCT03186989.

Abstract Background The authors sought to examine the impact of the K-variant of butyrylcholinesterase (BCHE-K) carrier status on age-at-diagnosis of Alzheimer disease (AD) in APOE4 carriers. Methods Patients aged 50–74 years with cerebrospinal fluid (CSF) biomarker-confirmed AD, were recruited to clinical trial (NCT03186989 since June 14, 2017). Baseline demographics, disease characteristics, and biomarkers were evaluated in 45 patients according to BCHE-K and APOE4 allelic status in this post-hoc study. Results In APOE4 carriers (N = 33), the mean age-at-diagnosis of AD in BCHE-K carriers (n = 11) was 6.4 years earlier than in BCHE-K noncarriers (n = 22, P

Extracellular amyloid plaques, intracellular neurofibrillary tangles, and loss of basal forebrain cholinergic neurons in the brains of Alzheimer's disease (AD) patients may be the end result of abnormalities in lipid metabolism and peroxidation that may be caused, or exacerbated, by β-amyloid peptide (Aβ). Apolipoprotein E (apoE) is a major apolipoprotein in the brain, mediating the transport and clearance of lipids and Aβ. ApoE-dependent dendritic and synaptic regeneration may be less efficient with apoE4, and this may result in, or unmask, age-related neurodegenerative changes. The increased risk of AD associated with apoE4 may be modulated by diet, vascular risk factors, and genetic polymorphisms that affect the function of other transporter proteins and enzymes involved in brain lipid homeostasis. Diet and apoE lipoproteins influence membrane lipid raft composition and the properties of enzymes, transporter proteins, and receptors mediating Aβ production and degradation, tau phosphorylation, glutamate and glucose uptake, and neuronal signal transduction. The level and isoform of apoE may influence whether Aβ is likely to be metabolized or deposited.This review examines the current evidence for diet, lipid homeostasis, and apoE in the pathogenesis of AD. Effects on the cholinergic system and response to cholinesterase inhibitors by APOE allele carrier status are discussed briefly.