The finding of early astrocytosis in the AD continuum is strengthened by recent findings of YKL-40, a potential astrocyte-derived biomarker measured in CSF, being strongly related to Aβ in AD patients and with tau pathology as a marker for neurodegeneration, most pronounced at early pre-dementia stages of AD42, 43, 44, 45. Here, MAPT is linked to Alzheimer disease.