NEFL and Mental deterioration: Low levels of CSF p-tau181 and a higher NfL/p-tau ratio predict progression on the PSPRS at 52-week follow-up.64 Low SCP volume correlates with higher CSF NfL levels64 and higher plasma NfL levels (>37.3 ng/mL) predicted increased severity on the PSPRS, SEADL and RBANS at follow-up.64 Higher plasma NfL levels are also predictive of greater whole-brain and SCP volume loss.65 However, no association between baseline plasma NfL levels and longitudinal cognitive decline measured by the ACE-R has been found.66