Auditory event-related potentials show both auditory and non-auditory associations with chronic mild traumatic brain injury

Objective: Auditory event-related potentials (ERP) may reflect chronic effects of repetitive mild traumatic brain injury (mild TBI), but the influence of auditory impairment on these ERP changes is unclear. Methods: We compared hearing sensitivity, complex auditory processing, and auditory cortical ERPs in combat veterans (N = 270) with and without mild TBI, TBI in combat deployment setting, blast TBI, post-traumatic amnesia (PTA), loss of consciousness, and non-TBI blast exposures. Mediation analysis assessed the hearing, age, and psychological symptom-adjusted effect of number of TBI exposures on P50 and N100 amplitude and latency, and whether ERPs mediated between TBI and complex auditory processing. Results: After adjustment, higher exposures to combat and blast TBI predicted larger P50 amplitudes; mild TBI with PTA was associated with longer P50 latency, which mediated speech in noise perception; combat blast exposures (non-TBI) were associated with reduced N100 amplitude. Conclusion: Auditory cortical response changes observed for higher exposure to blast or combat mild TBI and blast exposures were not attributable to auditory dysfunction or current psychological distress. In contrast, mild TBI with PTA predicted auditory cortical responses with behavioral consequences for speech processing in noise. Significance: Auditory P50 and N100 are promising biomarkers for both the non-auditory and auditory chronic effects of mild TBI on brain function.