NEFL and Alzheimer disease: The emergence of sensitive plasma biomarkers for AD pathology (e.g. Aβ42/40, p-tau181/p-tau217) and neurodegenerative processes (e.g. neurofilament light chain [NfL, a measure of axonal degeneration] and glial fibrillar acidic protein [GFAP, a measure of activated astrocytes]) has considerable implications for future diagnostic pathways, potentially allowing for cheaper and more widely available access to molecular biomarkers.