GFAP and Alzheimer disease: Plasma‐based measures of Aβ,1 phosphorylated tau (p‐tau),2 glial fibrillary acidic protein (GFAP),3 and neurofilament light chain (NfL)4 predict key AD‐related clinical outcomes, However, there are challenges to interpreting biomarker levels in the blood, as some chronic medical conditions can affect the clearance of circulating proteins, and most studies thus far have been in relatively healthy cohorts and have not considered medical comorbidities that are common in older adults that may affect blood protein levels.5