NEFL and Cognitive impairment: Repeated mTBI rats had acute cognitive deficits and prolonged sensorimotor impairments. Serum NfL was elevated at 7 days post-injury, correlating with sensorimotor deficits. Several hippocampal proteins were altered by repeated mTBI, including those associated with energy metabolism, neuroinflammation, and impaired neurogenic capacity. Diffusion MRI analysis at 3.5 months found widespread reductions in white matter integrity.