GFAP and Alzheimer disease: As such, it is proposed that 11C‐DED binding may reflect a ‘first‐wave’ of reactive astrogliosis, potentially in response to pre‐plaque soluble amyloid, whereas GFAP measured in biofluids may reflect more advanced amyloid pathology in AD progression, and thus a later reactive astrogliosis process (Fontana et al., 2023).