APOE and Alzheimer disease: In our initial analyses, we used linear mixed effects models, co-varying for baseline age, sex, presence ("carriers") or absence ("non-carriers") of at least one ε4 allele of apolipoprotein E (APOE ε4), diagnostic status (AD vs mild cognitive impairment (MCI) vs healthy elderly controls (HC)), and disease severity (CDR-Sum of Boxes score at baseline) to examine whether CSF HFABP levels are associated with longitudinal atrophy of the entorhinal cortex and other AD-vulnerable regions of interest ('AD vulnerable ROI’ – for additional details see Methods) (Figure 1).