NEURAL PROCESSING FUNCTION FOLLOWING CONCUSSION: A NARRATIVE REVIEW OF THE P300 EVENT-RELATED POTENTIAL COMPONENT

Abstract

Background: Mild traumatic brain injury (mTBI), or concussion, represents a significant public health concern. Current diagnostic practice relies on clinical tests and symptom reporting, as standard neuroimaging is unable to detect the microstructural changes of injury. This diagnostic gap creates challenging decision making for clinicians regarding diagnosis and medical clearance. The P300 event-related potential (ERP) measured via electroencephalography, is the most extensively studied neurophysiological measure in current concussion literature. Previous studies demonstrate changes in amplitude and latency reflecting functional deficits in the patient population. Objective: To summarize the evidence for how the P300 ERP component differs following concussion. We also summarized how the P300 changes throughout concussion recovery, and investigated whether or not differences exist between populations and mechanism of injury. Methods: A systematic literature search was conducted across Medline, PsychInfo, and Embase databases. Following title and abstract screening and full text review, 19 original studies were included, published between 1988 and 2025, across pediatric and adult cohorts. Studies were eligible if they assessed the auditory P300 ERP in a concussion population compared to baseline measurements or healthy controls. Results: P300 amplitude reduction was the most common finding, reported as significant across 10 of the 19 studies. This reduction was most consistently detected in sport-related concussion populations. P300 latency was less consistently altered, with 9 studies showing no significant change compared to controls. Prolonged latency was most reliably seen across the acute civilian concussion population, and chronically in blast-injured military cohorts. Two studies showed amplitude increases. Substantial variability in concussion definition, study design, ERP methodology, and population traits limited cross study comparison. Conclusion: The P300 ERP demonstrates potential as an objective, portable, and more accessible tool to supplement current clinical protocols. P300 abnormalities frequently persisted beyond symptom recovery and clinical clearance, which challenges the adequacy of symptom based return to activity protocols. The P300 shows promise as a prognostic marker of recovery trajectory and treatment monitoring tool rather than a standalone diagnostic marker. Future research should prioritize standardization of ERP evaluation tools, longitudinal studies with preinjury assessments in the non-sport population, and investigation of P300 within a broader multimodal biomarker framework.