In US military investigations, NfL and, to a lesser extent, tau were linked to chronic PCS symptoms and poor sleep quality.84 The Chronic Effects of Neurotrauma Consortium (CENC) study, which focused on war fighters with mTBI, observed a significant elevation of plasma NfL and a trend towards elevated plasma tau in the mTBI cohort with poor sleep quality.85 This evidence concerns the gene MAPT and concussion.