BackgroundMild cognitive impairment (MCI) confers an increased risk of Alzheimer's disease (AD). The apolipoprotein E (APOE) ε4 allele is a major genetic risk factor for late-onset AD and is strongly associated with amyloid-β (Aβ) pathology. However, whether Aβ burden is associated with APOE ε4-related longitudinal changes in tau pathology, neurodegeneration, and cognitive decline in MCI remains incompletely understood.ObjectiveTo examine whether Aβ burden is associated with APOE ε4-related long...