Flying After Concussion and Symptom Recovery in College Athletes and Military Cadets

Neurological Biomarker Profiles in Royal Canadian Air Force (RCAF) Pilots and Aircrew

BACKGROUND/OBJECTIVES

Military aviators can be exposed to extreme physiological stressors, including decompression stress, G-forces, as well as intermittent hypoxia and/or hyperoxia, which may contribute to neurobiological dysfunction/damage. This study aimed to investigate the levels of neurological biomarkers in military aviators to assess the potential risk of long-term brain injury and neurodegeneration.

METHODS

This cross-sectional study involved 48 Canadian Armed Forces (CAF) aviators and 48 non-aviator CAF controls. Plasma samples were analyzed for biomarkers of glial activation (GFAP), axonal damage (NF-L, pNF-H), oxidative stress (PRDX-6), and neurodegeneration (T-tau), along with S100b, NSE, and UCHL-1. The biomarker concentrations were quantified using multiplexed immunoassays.

RESULTS

The aviators exhibited significantly elevated levels of GFAP, NF-L, PRDX-6, and T-tau compared to the CAF controls (p < 0.001), indicating increased glial activation, axonal injury, and oxidative stress. Trends toward higher levels of S100b, NSE, and UCHL-1 were observed but were not statistically significant. The elevated biomarker levels suggest cumulative brain damage, raising concerns about potential long-term neurological impairments.

CONCLUSIONS

Military aviators are at increased risk for neurobiological injury, including glial and axonal damage, oxidative stress, and early neurodegeneration. These findings emphasize the importance of proactive monitoring and further research to understand the long-term impacts of high-altitude flight on brain health and to develop strategies for mitigating cognitive decline and neurodegenerative risks in this population.

An exploratory study into the relationship between playing at home or away and concussion

PRIMARY OBJECTIVE

To investigate the effect of home and away game travel on risk of concussion across different levels of rugby union.

RESEARCH DESIGN

Exploration study across school, university, and professional rugby teams.

METHODS AND PROCEDURES

Retrospective analysis of concussion incidence and symptomology of surveillance data and prospective data collection for potential concussions via surveys. Data was collected from school rugby teams (n = 344 matches, over 2 years), a university rugby (n = 6 matches), and a professional rugby team (n = 64 matches, over two seasons).

MAIN OUTCOMES AND RESULTS

School level rugby had an increased prevalence of concussions in away matches (p = 0.02). Likewise, there was a significant increase (p < 0.05) in concussions at away matches in university rugby. In addition, the professional rug by team had significant differences in recovery times and symptoms with away fixtures, including longer recovery times (p < 0.01), more initial symptoms (p < 0.01), as well as greater and more severe symptoms at 48 hours (p < 0.05).

CONCLUSIONS

This research highlights an increased prevalence of concussion in school and university-aged rugby players away from home, as well as increased symptoms, symptom severity, and recovery times in professional rugby players.

Combined traumatic brain injury and hemorrhagic shock in ferrets leads to structural, neurochemical, and functional impairments

Aeromedical evacuation-relevant hypobaria after traumatic brain injury (TBI) leads to increased neurologic injury and mortality in rats relative to those maintained under normobaria. However, applicability of rodent brain injury research to humans may be limited by differences in neuroanatomy. Therefore, we developed a model in which ferrets are exposed to polytrauma consisting of controlled cortical impact TBI and hemorrhagic shock subjected 24 h later to 6 h of hypobaria or normobaria. Our objective was to determine if the deleterious effects of hypobaria observed in rats, with lissencephalic brains, are also present in a species with a human-like gyrencephalic brain. While no mortality was observed, magnetic resonance spectroscopy (MRS) results obtained 2 days post-injury indicated reduced cortical creatine, N-acetylaspartate, GABA, myo-inositol, and glutamate which was not affected by hypobaria. T2-weighted magnetic resonance imaging (MRI) quantification revealed increased hyperintensity volume representing cortical edema at the site of impact following polytrauma. Hypobaria did not exacerbate this focal edema but did lead to overall reductions in total cortical volume. Both normobaric and hypobaric ferrets exhibited impaired spatial memory 6 days post-injury on the Object Location Test, but no differences were noted between groups. Finally, cortical lesion volume was not exacerbated by hypobaria exposure on day 7 post-injury. Results suggest that air travel 24 h after polytrauma is associated with structural changes in the ferret brain. Future studies should investigate secondary injury from hypobaria following polytrauma in greater detail including alternative outcome measures, timepoints, and exposure to multiple flights.

Prospective Evaluation of Health Outcomes in a Nationwide Sample of Aeromedical Evacuation Casualties: Methods From a Pilot Study

INTRODUCTION

Although retrospective analyses have found that combat-injured service members are at high risk for mental and physical health outcomes following injury, relatively little is known about the long-term health of injured service members. To better understand long-term health outcomes after combat injury, a large, prospective observational cohort collecting both subjective and objective health data is needed. Given that a study of this nature would be costly and face many logistical challenges, we first conducted a pilot to assess the feasibility of a larger, definitive study.

MATERIALS AND METHODS

We ran a prospective, observational pilot study of 119 combat-injured service members and veterans who completed (1) at least one set of laboratory measurements (blood and urine sample collection and vitals measurements) at Clinical Laboratory Improvement Amendment of 1988 compliant laboratory locations and (2) at least one online assessment for the Wounded Warrior Recovery Project (WWRP), a 15-year examination of patient-reported outcomes among service members injured on combat deployment. We recruited the pilot study cohort from WWRP participants who met eligibility criteria and indicated interest in additional research opportunities. We collected laboratory values and patient-reported outcomes at baseline and again 1 year later, and obtained demographic, injury, and military service data from the Expeditionary Medical Encounter Database. The David Grant USAF Medical Center Institution Review Board (IRB) and the Naval Health Research Center IRB reviewed and approved the study protocols.

RESULTS

During recruitment for the pilot study, 624 study candidates were identified from WWRP. Of the 397 candidates we contacted about the pilot study, 179 (45.1%) enrolled and 119 (66.4%) of those who enrolled completed the first year of participation. The second study year was suspended due to the coronavirus disease-2019 pandemic. At the time of suspension, 72 (60.5%) participants completed follow-up laboratory appointments, and 111 (93.3%) completed second-year WWRP assessments. Participants in the pilot study were predominately male (95.0%) and non-Hispanic White (55.5%), with a median (interquartile range) age of 38.3 (34.1-45.4) years.

CONCLUSIONS

Collection of patient-reported outcomes and laboratory samples in a geographically dispersed cohort of combat-injured service members is possible. While significant challenges exist, our pilot study results indicate that a larger, longitudinal, cohort study is feasible.