Peltz CB, Kenney K, Gill J, et al. - This study was undertaken to determine if blood-based biomarkers may differentiate older veterans with and without traumatic brain injury (TBI) and cognitive impairment (CogI). The sample consisted of 155 veterans (90 without TBI and 65 with TBI history) from 2 veterans' retirement homes. Study participants were further separated into CogI groups: controls (no TBI, no CogI), n = 60; no TBI with CogI, n = 30; TBI without CogI, n = 30; and TBI with CogI, n = 35. Using ultrasensitive immunoassays, proteins (neurofilament light [NfL], total tau, glial fibrillary acidic protein, α-synuclein, β-amyloid 42 [Aβ42], and phosphorylated tau [p-tau]) and cytokines (tumor necrosis factor–α [TNF-α], interleukin-6, and interleukin-10) have been measured. Even decades after TBI, increased levels of blood-based, CNS-enriched exosomal biomarkers associated with TBI and CogI may be detected.