NEFL and brain injury: However, tau has less central nervous system (CNS) specificity than NfL as tau is also released after polytrauma.114 CSF NfL levels show high sensitivity for acute neuronal injury, including in boxers with mTBI.115 NfL levels in serum correlate with their CSF levels (r = 0.71),116 and recent reports show elevation in acute TBI across the spectrum of severity.116,117 Higher plasma tau levels collected within the first 6 h after injury may be prognostic of prolonged recovery from acute sports concussion.