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Longitudinal trajectories and risk factors for persistent postconcussion symptom reporting following uncomplicated mild traumatic brain injury in U.S. Military service members

Abstract Objective The purpose of this study was to examine individual postconcussion symptom [PCSx] trajectories following mild traumatic brain injury (MTBI), and to examine risk factors for persistent PCSx reporting. Method Participants were 138 U.S. military service members and veterans (SMVs) prospectively enrolled in the Defense and Veterans Brain Injury Center, 15-Year Longitudinal TBI study. Participants were classified into three groups: uncomplicated MTBI (n = 54), injured controls (IC, n = 26), and non-injured controls (NIC, n = 58). Participants completed the Neurobehavioral Symptom Inventory, PTSD Checklist, and Traumatic Brain Injury Quality of Life at baseline (<8 months post-injury) and at follow-up (2–4 years post-injury). Results The prevalence of those who met DSM-IV-TR symptom criteria for Postconcussional Disorder (PCD) was high in all three groups (e.g., 44.8–63.0%) and did not significantly change from baseline to follow-up (all ps>.05). However, there was substantial variability in individual symptom trajectories over time. The majority of participants had symptom trajectories classified as either ‘persistent’ (∼32–55%) or ‘asymptomatic’ (∼30–36%), with a substantial minority classified as ‘improved’ (∼7–12%) or ‘developed’ (∼7–19%). Factors associated with ‘persistent’ PCD trajectories included cognitive complaints, PTSD, depression, anxiety, pain, and headaches at baseline; but not the presence/absence of MTBI. Factors associated with ‘developed’ PCD trajectories included PTSD and the number of lifetime exposures to blast. Conclusions: Reporting of ‘new’ PCSx over time was common in individuals with and without MTBI. It would be erroneous to assume uncritically that PCSx reported many years post-injury reflect only persistent symptomatology, or can be solely attributable to the direct consequences of a brain injury.