GFAP and frontotemporal dementia: Non‐core BBMs neurofilament light (NfL) and glial fibrillary acidic protein (GFAP) reflect neurodegeneration and astrocyte reactivity, which are important pathogenic processes that play a role in AD,2 as well as in other neurological diseases (e.g., frontotemporal dementia, multiple sclerosis).6, 7