Accelerated long-term forgetting (ALF) refers to a rapid loss of information over days or weeks despite normal acquisition/encoding. Notwithstanding its potential relevance as a presymptomatic marker of cognitive dysfunction, no study has addressed the relationship between ALF and Alzheimer’s disease (AD) biomarkers. We examined ALF in APOE ɛ4 carriers versus noncarriers, and its relationships with AD cerebrospinal fluid (CSF) biomarkers. We found ALF over three months in APOE ɛ4 carriers (F(1,19) = 5.60; P < 0.05; Cohen’s d = 1.08), and this performance was associated with abnormal levels of the CSF Aβ₄₂ /ptau ratio (r = -.614; P < 0.01). Our findings indicate that ALF is detectable in at-risk individuals, and that there is a relationship between ALF and the pathophysiological processes underlying AD.