Peritraumatic Context and Long-Term Outcomes of Concussion.

Importance: There has been a great deal of interest in mild traumatic brain injury (mTBI) and posttraumatic stress disorder (PTSD) and their association with one another, yet their interaction and subsequent associations with long-term outcomes remain poorly understood. Objective: To compare the long-term outcomes of mTBI that occurred in the context of psychological trauma (peritraumatic context) with mTBI that did not (nonperitraumatic context). Design, Setting, and Participants: This cohort study of post-9/11 US veterans used data from the Translational Research Center for Traumatic Brain Injury and Stress Disorders (TRACTS) study at the Veterans Affairs Boston Healthcare System, which began in 2009; the current study utilized data from baseline TRACTS visits conducted between 2009 and 2024. Data analysis occurred from January to October 2024. Exposures: Peritraumatic mTBI, nonperitraumatic mTBI, or no TBI. Main Outcomes and Measures: The primary outcomes were PTSD severity (measured by the Clinician-Administered PTSD Scale-4th edition), postconcussive symptoms (measured by the Neurobehavioral Symptom Inventory), and self-reported disability status (measured by the World Health Organization Disability Assessment Schedule II). Differences between groups were compared using analyses of covariance with least significant difference comparisons. Results: This sample of 567 post-9/11 veterans (mean [SD] age, 33.72 [9.29] years; 507 men [89.4%]; mean [SD] years of education, 14.19 [2.16]) included 183 individuals with no TBI, 189 individuals with nonperitraumatic mTBI, and 195 individuals with peritraumatic mTBI. Veterans with a history of peritraumatic mTBI had greater PTSD severity (F2,552 = 8.45; P < .001), postconcussive symptoms (F2,533 = 11.09; P < .001), and disability (F2,527 = 11.13; P < .001) than the nonperitraumatic mTBI and no TBI groups. Importantly, no significant differences in any outcome measure between nonperitraumatic mTBI and no TBI groups were observed. Conclusions and Relevance: This cohort study found that mTBI was only associated with long-term consequences when it co-occurred with a traumatic event exposure. This finding raises a novel hypothesis of the association of mTBI with PTSD, in which the acute biological and physiological outcomes of mTBI may be associated with temporarily scaffolding the formation of PTSD symptoms, which could enhance the production of long-term postconcussive symptoms and disability.