Long-term neurobehavioural symptom reporting following mild, moderate, severe, and penetrating traumatic brain injury in U.S. military service members.

The purpose of this study was to examine long-term neurobehavioural symptom reporting following mild, moderate, severe, or penetrating TBI in U.S. military service members and veterans (SMV). Participants were 445 SMVs divided into four groups: 158 uncomplicated mild TBI ("unMTBI" group), 105 penetrating, severe, moderate, or complicated mild TBI ("smcTBI" group), 101 injured controls (IC), and 81 non-injured controls (NIC). Two independent cohorts were examined that included participants 5-years or 10-year post-injury. Participants completed the TBI-Quality of Life, Neurobehavioural Symptom Inventory, and Post-traumatic Stress Disorder Checklist. At 5-years and 10-years post-injury, there were significant main effects for the majority of measures (all p's < .005). At 10-years post-injury, the NIC group had consistently better scores compared to the IC, unMTBI, and smcTBI groups. At 5-years post-injury, either (a) the IC and NIC group had better scores compared to both TBI groups, or (b) the NIC group had better scores compared to the IC, unMTBI, and smcTBI groups. A high proportion of SMVs reported poor long-term neurobehavioural symptoms following TBI or bodily injury without TBI. Injured SMVs (regardless of injury type) can have long-term symptoms that impact mental health and overall quality of life requiring long-term follow-up and care.

High Lifetime Blast Exposure Using the Blast Exposure Threshold Survey Is Associated With Worse Warfighter Brain Health Following Mild Traumatic Brain Injury.

The purpose of this study was to extend previous research by examining the relationship between lifetime blast exposure and neurobehavioral functioning after mild TBI (MTBI) by (a) using a comprehensive measure of lifetime blast exposure, and (b) controlling for the influence of post-traumatic stress disorder (PTSD). Participants were 103 United States service members and veterans (SMVs) with a medically documented diagnosis of MTBI, recruited from three military treatment facilities (74.8%) and community-based recruitment initiatives (25.2%, e.g., social media, flyers). Participants completed a battery of neurobehavioral measures 12 or more months post-injury (Neurobehavioral Symptom Inventory, PTSD-Checklist PCLC, TBI-Quality of Life), including the Blast Exposure Threshold Survey (BETS). The sample was classified into two lifetime blast exposure (LBE) groups: High (n = 57) and Low (n = 46) LBE. In addition, the sample was classified into four LBE/PTSD subgroups: High PTSD/High LBE (n = 38); High PTSD/Low LBE (n = 19); Low PTSD/High LBE (n = 19); and Low PTSD/Low LBE (n = 27). The High LBE group had consistently worse scores on all neurobehavioral measures compared with the Low LBE group. When controlling for the influence of PTSD (using ANCOVA), however, only a handful of group differences remained. When comparing measures across the four LBE/PTSD subgroups, in the absence of clinically meaningful PTSD symptoms (i.e., Low PTSD), participants with High LBE had worse scores on the majority of neurobehavioral measures (e.g., post-concussion symptoms, sleep, fatigue). When examining the total number of clinically elevated measures, the High LBE subgroup consistently had a greater number of clinically elevated scores compared with the Low LBE subgroup for the majority of comparisons (i.e., four to 15 or more elevated symptoms). In contrast, in the presence of clinically meaningful PTSD symptoms (i.e., High PTSD), there were no differences between High versus Low LBE subgroups for all measures. When examining the total number of clinically elevated measures, however, there were meaningful differences between High versus Low LBE subgroups for those comparisons that included a high number of clinically elevated scores (i.e., six to 10 or more), but not for a low number of clinically elevated scores (i.e., one to five or more). High LBE, as quantified using a more comprehensive measure than utilized in past research (i.e., BETS), was associated with worse overall neurobehavioral functioning after MTBI. This study extends existing literature showing that lifetime blast exposure, that is largely subconcussive, may negatively impact warfighter brain health and readiness beyond diagnosable brain injury.