NfL correlated with post-concussion symptoms (rs = − 0.38, p = 0.04) in the mTBI group, and with PTSD symptoms in mTBI (rs = − 0.43, p = 0.021) and smcTBI groups (rs = − 0.40, p = 0.024) within one year after injury, which was not confirmed in regression models. This evidence concerns the gene NEFL and post-traumatic stress disorder.