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

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' (similar to 32-55%) or 'asymptomatic' (similar to 30-36%), with a substantial minority classified as 'improved' (similar to 7-12%) or 'developed' (similar to 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.