GFAP and Alzheimer disease: Although dynamics of CSF GFAP have been somewhat inconsistent in AD,47,48,49,50 recent studies show plasma GFAP levels to reliably increase in early stage sAD and DIAD,51,52 predict PiB-PET positivity49,53 and correlate with longitudinal amyloid PET54 and cognitive decline.49 Plasma GFAP levels in carriers of DIAD gene variants seem to diverge from noncarriers around 16 years before expected symptom onset, corroborating findings of early changes in sAD.55 Interestingly, we found no relevant treatment-related differences in CSF GFAP levels for either drug.