Although astrocyte activation is not specific to AD pathophysiology, plasma GFAP was found to be more sensitive for the early diagnosis of AD than Aβ-PET, CSF and plasma p-tau181, and CSF total tau (Guo et al., 2023), and it linearly increased with increasing Aβ-PET burden (Asken et al., 2020). Here, GFAP is linked to Alzheimer disease.