MAPT and Alzheimer disease: These results along with our finding of correlations between NfL and CSF tau, but not CSF Aβ1–42 and CSF Aβ42/Aβ40 ratio reinforce the role of NfL as a marker for neuronal injury [2], although not in an AD specific fashion as, in line with previous work, NfL appears independent of amyloid pathology [24].