NEFL and Alzheimer disease: Biomarkers of AD currently used in research and clinical settings include those for Aβ and tau pathology (e.g., CSF and plasma Aβ42/Aβ40 ratio and phosphorylated-tau, as well as amyloid and tau positron emission tomography (PET)), synaptic loss (e.g., CSF neurogranin and fluorodeoxyglucose (FDG) PET), neurodegeneration (e.g., volumetric magnetic resonance imaging (MRI), and neurofilament light (NfL) concentration in CSF and blood), and inflammation (e.g., CSF YKL-40 and CSF soluble triggering receptor expressed on myeloid cells 2 (sTREM2) and translocator protein (TSPO)) [102, 103].