While the biological reasons for elevations of NT1- and MR-detected forms of tau are unclear, measurement of these analytes in CSF allow for a perfect or near-perfect separation of CJD patients from controls (AUC = 1 for both NT1-tau and MR-tau) and AD subjects (AUC = 1 for NT1-tau, and 0.98 for MR-tau, Supplemental Figure S2), and is slightly better than that obtained with NfL (Supplemental Figure S2). Here, NEFL is linked to Alzheimer disease.