Health Outcomes Associated With Military Deployment: Mild Traumatic Brain Injury, Blast, Trauma, and Combat Associations in the Florida National Guard

Early Clinical Predictors of 5-Year Outcome After Concussive Blast Traumatic Brain Injury

Importance

The long-term clinical effects of wartime traumatic brain injuries (TBIs), most of which are mild, remain incompletely described. Current medical disability cost estimates from world conflicts continually surpass projections. Additional information regarding long-term functional trajectory is needed to reduce this extensive public health burden.

Objectives

To examine 5-year clinical outcomes leveraging existing clinical data collected at 1 year after injury in the same patients and to identify early risk factors for long-term disability.

Design, Setting, and Participants

This prospective, longitudinal study enrolled active-duty US military after concussive blast injury (n = 50) in the acute to subacute stage and combat-deployed control individuals (n = 44) in Afghanistan or after medical evacuation to Germany from November 1, 2008, through July 1, 2013. One- and 5-year clinical evaluations were completed in the United States. All concussive blast injuries met the Department of Defense definition of mild, uncomplicated TBI. In-person clinical evaluations included standardized evaluations for neurobehavior, neuropsychological performance, and mental health burden that were essentially identical to the evaluations completed at 1-year follow-up. Data were analyzed from October 1 through November 30, 2016.

Main Outcomes and Measures

Changes in the in-person standardized evaluations for neurobehavior, neuropsychological performance, and mental health burden from the 1- to 5-year follow-up. Predictive modeling was used to identify early risk factors for long-term disability.

Results

Among the 94 participants (87 men [93%] and 7 women [7%]; mean [SD] age, 34 [8] years), global disability, satisfaction with life, neurobehavioral symptom severity, psychiatric symptom severity, and sleep impairment were significantly worse in patients with concussive blast TBI compared with combat-deployed controls, whereas performance on cognitive measures was no different between groups at the 5-year evaluation. Logistic regression on the dichotomized Extended Glasgow Outcome Scale (GOS-E) at 5 years as a measure of overall disability identified brain injury diagnosis, preinjury intelligence, motor strength, verbal fluency, and neurobehavioral symptom severity at 1 year as risk factors for a poor outcome at 5 years, with an area under the curve of 0.92 indicating excellent prediction strength. Thirty-six of 50 patients with concussive blast TBI (72%) had a decline in the GOS-E from the 1- to 5-year evaluations, in contrast with only 5 of 44 combat-deployed controls (11%). Worsening of symptoms in concussive blast TBI was also observed on measures of posttraumatic stress disorder and depression. Service members with concussive blast TBI experienced evolution, not resolution, of symptoms from the 1- to 5-year outcomes.

Conclusions and Relevance

Considerable decline was observed in military service members with concussive blast TBI when comparing 1- and 5-year clinical outcomes. These results advocate for new treatment strategies to combat the long-term and extremely costly effect of these wartime injuries.

The Effects of Blast Exposure on Protein Deimination in the Brain

Oxidative stress and calcium excitotoxicity are hallmarks of traumatic brain injury (TBI). While these early disruptions may be corrected over a relatively short period of time, long-lasting consequences of TBI including impaired cognition and mood imbalances can persist for years, even in the absence of any evidence of overt injury based on neuroimaging. This investigation examined the possibility that disordered protein deimination occurs as a result of TBI and may thus contribute to the long-term pathologies of TBI. Protein deimination is a calcium-activated, posttranslational modification implicated in the autoimmune diseases rheumatoid arthritis and multiple sclerosis, where aberrant deimination creates antigenic epitopes that elicit an autoimmune attack. The present study utilized proteomic analyses to show that blast TBI alters the deimination status of proteins in the porcine cerebral cortex. The affected proteins represent a small subset of the entire brain proteome and include glial fibrillary acidic protein and vimentin, proteins reported to be involved in autoimmune-based pathologies. The data also indicate that blast injury is associated with an increase in immunoglobulins in the brain, possibly representing autoantibodies directed against novel protein epitopes. These findings indicate that aberrant protein deimination is a biomarker for blast TBI and may therefore underlie chronic neuropathologies of head injury.

A Systems Science Approach to Understanding Polytrauma and Blast-Related Injury: Bayesian Network Model of Data From a Survey of the Florida National Guard

We sought to further define the epidemiology of the complex, multiple injuries collectively known as polytrauma/blast-related injury (PT/BRI). Using a systems science approach, we performed Bayesian network modeling to find the most accurate representation of the complex system of PT/BRI and identify key variables for understanding the subsequent effects of blast exposure in a sample of Florida National Guard members (1,443 deployed to Operation Enduring Freedom/Operation Iraqi Freedom and 1,655 not deployed) who completed an online survey during the period from 2009 to 2010. We found that postdeployment symptoms reported as present at the time of the survey were largely independent of deployment per se. Blast exposure, not mild traumatic brain injury (TBI), acted as the primary military deployment-related driver of PT/BRI symptoms. Blast exposure was indirectly linked to mild TBI via other deployment-related traumas and was a significant risk for a high level of posttraumatic stress disorder (PTSD) arousal symptoms. PTSD arousal symptoms and tinnitus were directly dependent upon blast exposure, with both acting as bridge symptoms to other postdeployment mental health and physical symptoms, respectively. Neurobehavioral or postconcussion-like symptoms had no significant dependence relationship with mild TBI, but they were synergistic with blast exposure in influencing PTSD arousal symptoms. A replication of this analysis using a larger PT/BRI database is warranted.

Resilience and Traumatic Brain Injury Among Iraq/Afghanistan War Veterans: Differential Patterns of Adjustment and Quality of Life

OBJECTIVE

We examined the degree to which a resilient personality prototype predicted adjustment among war Veterans with and without a traumatic brain injury (TBI) while covarying the level of combat exposure.

METHOD

A total of 127 war Veterans (107 men, 20 women; average age = 37 years) participated. Personality prototypes were derived from the Multidimensional Personality Questionnaire (Patrick, Curtain, & Tellegen, 2002). Measures were administered at baseline, and a subset was administered at 4- and 8-month follow-ups.

RESULTS

Veterans with resilient personalities reported less sleep disturbance, more health-promoting behaviors, psychological flexibility, and emotional distress tolerance than Veterans with undercontrolled or overcontrolled prototypes. Path models revealed that resilience significantly predicted posttraumatic stress disorder (PTSD), depression, quality of life, and social support over time. TBI had unique and consistent effects only on PTSD.

CONCLUSION

Personality characteristics influence distress and quality of life among war Veterans with and without TBI. Implications for assessment, interventions, and research are discussed.

Clinical Utility and Psychometric Properties of the Traumatic Brain Injury Quality of Life Scale (TBI-QOL) in US Military Service Members

OBJECTIVE

To examine the clinical utility and psychometric properties of the Traumatic Brain Injury Quality of Life (TBI-QOL) scale in a US military population.

PARTICIPANTS

One hundred fifty-two US military service members (age: M = 34.3, SD = 9.4; 89.5% men) prospectively enrolled from the Walter Reed National Military Medical Center and other nationwide community outreach initiatives. Participants included 99 service members who had sustained a mild traumatic brain injury (TBI) and 53 injured or noninjured controls without TBI (n = 29 and n = 24, respectively).

PROCEDURE

Participants completed the TBI-QOL scale and 5 other behavioral measures, on average, 33.8 months postinjury (SD = 37.9).

MAIN OUTCOME MEASURES

Fourteen TBI-QOL subscales; Neurobehavioral Symptom Inventory; Posttraumatic Stress Disorder Checklist-Civilian version; Alcohol Use Disorders Identification Test; Combat Exposure Scale.

RESULTS

The internal consistency reliability of the TBI-QOL scales ranged from α = .91 to α = .98. The convergent and discriminant validity of the 14 TBI-QOL subscales was high. The mild TBI group had significantly worse scores on 10 of the 14 TBI-QOL subscales than the control group (range, P < .001 to P = .043). Effect sizes ranged from medium to very large (d = 0.35 to d = 1.13). The largest differences were found on the Cognition-General Concerns (d = 1.13), Executive Function (d = 0.94), Grief-Loss (d = 0.88), Pain Interference (d = 0.83), and Headache Pain (d = 0.83) subscales.

CONCLUSION

These results support the use of the TBI-QOL scale as a measure of health-related quality of life in a mild TBI military sample. Additional research is recommended to further evaluate the clinical utility of the TBI-QOL scale in both military and civilian settings.

Volumetric and shape analyses of subcortical structures in United States service members with mild traumatic brain injury

Mild traumatic brain injury (mTBI) is a significant health concern. The majority who sustain mTBI recover, although ~20 % continue to experience symptoms that can interfere with quality of life. Accordingly, there is a critical need to improve diagnosis, prognostic accuracy, and monitoring (recovery trajectory over time) of mTBI. Volumetric magnetic resonance imaging (MRI) has been successfully utilized to examine TBI. One promising improvement over standard volumetric approaches is to analyze high-dimensional shape characteristics of brain structures. In this study, subcortical shape and volume in 76 Service Members with mTBI was compared to 59 Service Members with orthopedic injury (OI) and 17 with post-traumatic stress disorder (PTSD) only. FreeSurfer was used to quantify structures from T1-weighted 3 T MRI data. Radial distance (RD) and Jacobian determinant (JD) were defined vertex-wise on parametric mesh-representations of subcortical structures. Linear regression was used to model associations between morphometry (volume and shape), TBI status, and time since injury (TSI) correcting for age, sex, intracranial volume, and level of education. Volumetric data was not significantly different between the groups. JD was significantly increased in the accumbens and caudate and significantly reduced in the thalamus of mTBI participants. Additional significant associations were noted between RD of the amygdala and TSI. Positive trend-level associations between TSI and the amygdala and accumbens were observed, while a negative association was observed for third ventricle. Our findings may aid in the initial diagnosis of mTBI, provide biological targets for functional examination, and elucidate regions that may continue remodeling after injury.

Tailoring the Blast Exposure Conditions in the Shock Tube for Generating Pure, Primary Shock Waves: The End Plate Facilitates Elimination of Secondary Loading of the Specimen

The end plate mounted at the mouth of the shock tube is a versatile and effective implement to control and mitigate the end effects. We have performed a series of measurements of incident shock wave velocities and overpressures followed by quantification of impulse values (integral of pressure in time domain) for four different end plate configurations (0.625, 2, 4 inches, and an open end). Shock wave characteristics were monitored by high response rate pressure sensors allocated in six positions along the length of 6 meters long 229 mm square cross section shock tube. Tests were performed at three shock wave intensities, which was controlled by varying the Mylar membrane thickness (0.02, 0.04 and 0.06 inch). The end reflector plate installed at the exit of the shock tube allows precise control over the intensity of reflected waves penetrating into the shock tube. At the optimized distance of the tube to end plate gap the secondary waves were entirely eliminated from the test section, which was confirmed by pressure sensor at T4 location. This is pronounced finding for implementation of pure primary blast wave animal model. These data also suggest only deep in the shock tube experimental conditions allow exposure to a single shock wave free of artifacts. Our results provide detailed insight into spatiotemporal dynamics of shock waves with Friedlander waveform generated using helium as a driver gas and propagating in the air inside medium sized tube. Diffusion of driver gas (helium) inside the shock tube was responsible for velocity increase of reflected shock waves. Numerical simulations combined with experimental data suggest the shock wave attenuation mechanism is simply the expansion of the internal pressure. In the absence of any other postulated shock wave decay mechanisms, which were not implemented in the model the agreement between theory and experimental data is excellent.

Treatment of persistent post-concussive symptoms after mild traumatic brain injury: a systematic review of cognitive rehabilitation and behavioral health interventions in military service members and veterans

Increased prevalence of traumatic brain injury (TBI) has been associated with service members and veterans who completed combat deployments in support of Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF). Management of persistent post-concussive symptoms (PCS) has been a challenge to healthcare providers throughout the Military and Veterans Healthcare Systems, as well as civilian healthcare providers, due in part to the chronic nature of symptoms, co-occurrence of behavioral health disorders such as depression, Posttraumatic Stress Disorder (PTSD), and substance use disorders, and fear of a potential stigma associated with psychiatric diagnoses and behavioral health treatment(s). This systematic review examined non-pharmacologic behavioral health interventions and cognitive rehabilitation interventions for PCS in military service members and veterans with a history of mild TBI (mTBI). Six electronic databases were searched with specific term limitations, identifying 121 citations. Ultimately, 19 articles met criteria for inclusion in this systematic review. Studies were broadly categorized into four subtypes: psychoeducational interventions, cognitive rehabilitation, psychotherapeutic approaches, and integrated behavioral health interventions for PCS and PTSD. The review provides an update of the empirical evidence for these four types of interventions for PCS in active duty service members and veterans. Recommendations for future research are discussed, including the need to expand and improve the limited evidence basis on how to manage persistent post-concussive symptoms in this population.

Subgroups of US IRAQ and Afghanistan veterans: associations with traumatic brain injury and mental health conditions

U. S. veterans of Iraq and Afghanistan are known to have a high prevalence of traumatic brain injury (TBI), posttraumatic stress disorder (PTSD), and depression, which are often comorbid and share many symptoms. Attempts to describe this cohort by single diagnoses have limited our understanding of the complex nature of this population. The objective of this study was to identify subgroups of Iraq and Afghanistan veterans (IAVs) with distinct compositions of symptoms associated with TBI, PTSD, and depression. Our cross-sectional, observational study included 303,716 IAVs who received care in the Veterans Health Administration in 2010-2011. Symptoms and conditions were defined using International Classification of Diseases, Ninth Revision codes and symptom-clusters were identified using latent class analysis. We identified seven classes with distinct symptom compositions. One class had low probability of any condition and low health care utilization (HCU) (48 %). Other classes were characterized by high probabilities of mental health comorbidities (14 %); chronic pain and sleep disturbance (20 %); headaches and memory problems (6 %); and auditory problems (2.5 %). Another class had mental health comorbidities and chronic pain (7 %), and the last had high probabilities of most symptoms examined (3 %). These last two classes had the highest likelihood of TBI, PTSD, and depression and were identified as high healthcare utilizers. There are subgroups of IAVs with distinct clusters of symptom that are meaningfully associated with TBI, PTSD, depression, and HCU. Additional studies examining these veteran subgroups could improve our understanding of this complex comorbid patient population.

[Formula: see text]Interpreting change on the neurobehavioral symptom inventory and the PTSD checklist in military personnel

OBJECTIVE

The purpose of this study was to examine the prevalence and stability of symptom reporting in a healthy military sample and to develop reliable change indices for two commonly used self-report measures in the military health care system.

PARTICIPANTS AND METHOD

Participants were 215 U.S. active duty service members recruited from Fort Bragg, NC as normal controls as part of a larger study. Participants completed the Neurobehavioral Symptom Inventory (NSI) and Posttraumatic Checklist (PCL) twice, separated by approximately 30 days.

RESULTS

Depending on the endorsement level used (i.e. ratings of 'mild' or greater vs. ratings of 'moderate' or greater), approximately 2-15% of this sample met DSM-IV symptom criteria for Postconcussional Disorder across time points, while 1-6% met DSM-IV symptom criteria for Posttraumatic Stress Disorder. Effect sizes for change from Time 1 to Time 2 on individual symptoms were small (Cohen's d = .01 to .13). The test-retest reliability for the NSI total score was r = .78 and the PCL score was r = .70. An eight-point change in symptom reporting represented reliable change on the NSI total score, with a seven-point change needed on the PCL.

CONCLUSIONS

Postconcussion-like symptoms are not unique to mild TBI and are commonly reported in a healthy soldier sample. It is important for clinicians to use normative data when evaluating a service member or veteran and when evaluating the likelihood that a change in symptom reporting is reliable and clinically meaningful.

Primary blast causes mild, moderate, severe and lethal TBI with increasing blast overpressures: Experimental rat injury model

Injury severity in blast induced Traumatic Brain Injury (bTBI) increases with blast overpressure (BOP) and impulse in dose-dependent manner. Pure primary blast waves were simulated in compressed gas shock-tubes in discrete increments. Present work demonstrates 24 hour survival of rats in 0–450 kPa (0–800 Pa∙s impulse) range at 10 discrete levels (60, 100, 130, 160, 190, 230, 250, 290, 350 and 420 kPa) and determines the mortality rate as a non-linear function of BOP. Using logistic regression model, predicted mortality rate (PMR) function was calculated, and used to establish TBI severities. We determined a BOP of 145 kPa as upper mild TBI threshold (5% PMR). Also we determined 146–220 kPa and 221–290 kPa levels as moderate and severe TBI based on 35%, and 70% PMR, respectively, while BOP above 290 kPa is lethal. Since there are no standards for animal bTBI injury severity, these thresholds need further refinements using histopathology, immunohistochemistry and behavior. Further, we specifically investigated mild TBI range (0–145 kPa) using physiological (heart rate), pathological (lung injury), immuno-histochemical (oxidative/nitrosative and blood-brain barrier markers) as well as blood borne biomarkers. With these additional data, we conclude that mild bTBI occurs in rats when the BOP is in the range of 85–145 kPa.

Choosing appropriate comparison group participants in studies of veterans: Characteristics of orthopedically injured and uninjured Operation Enduring Freedom/Operation Iraqi Freedom/Operation New Dawn veterans

INTRODUCTION

Research addressing deployment-related traumatic brain injury (TBI) is fairly complex due to a high prevalence of comorbid conditions, multiple exposures, and the lack of acute medical records. Therefore, there is a need for a well-defined, matching comparison group. This study compared deployment-related characteristics, everyday functioning, and cognitive performance in recently deployed veterans who had not sustained any injuries with those who had orthopedic injuries during deployment, but who were without a history of TBI.

METHOD

Participants included 45 individuals who had been deployed and who were without injuries and a group of 27 individuals who reported at least one orthopedic injury during deployment. The Mayo-Portland Adaptability Inventory-4, Community Integration Questionnaire, Veterans RAND 36 Item Health Survey, Brief Pain Inventory, Barratt Impulsiveness Scale-11, and posttraumatic stress disorder (PTSD) Checklist-Civilian (PCL-C) were used to assess daily functioning. Cognitive performance was measured using the Controlled Oral Word Association Test, Trail Making Test, Color-Word Interference Test, and Verbal Selective Reminding Test. The two groups were compared using t tests based on equal variances. The effect size was calculated.

RESULTS

There were no between-group differences, with all variables having p-values >.1 and small to medium effect sizes.

DISCUSSION

Orthopedic injuries sustained during deployment that did not require evacuation or hospitalization did not have any lasting effect on participants' health, cognition, and daily functioning relative to other deployed individuals with no history of injury. These results indicate the two groups are comparable and that their data could be potentially combined to create a single comparison group. Due to the small sample available for this study, the current results are considered preliminary, and further investigation is needed.

Deficits in Visual System Functional Connectivity after Blast-Related Mild TBI are Associated with Injury Severity and Executive Dysfunction

INTRODUCTION

Approximately, 275,000 American service members deployed to Iraq or Afghanistan have sustained a mild traumatic brain injury (mTBI), with 75% of these incidents involving an explosive blast. Visual processing problems and cognitive dysfunction are common complaints following blast-related mTBI.

METHODS

In 127 veterans, we examined resting fMRI functional connectivity (FC) of four key nodes within the visual system: lateral geniculate nucleus (LGN), primary visual cortex (V1), lateral occipital gyrus (LO), and fusiform gyrus (FG). Regression analyses were performed (i) to obtain correlations between time-series from each seed and all voxels in the brain, and (ii) to identify brain regions in which FC variability was related to blast mTBI severity. Blast-related mTBI severity was quantified as the sum of the severity scores assigned to each of the three most significant blast-related injuries self-reported by subjects. Correlations between FC and performance on executive functioning tasks were performed across participants with available behavioral data (n = 94).

RESULTS

Greater blast mTBI severity scores were associated with lower FC between: (A) LGN seed and (i) medial frontal gyrus, (ii) lingual gyrus, and (iii) right ventral anterior nucleus of thalamus; (B) V1 seed and precuneus; (C) LO seed and middle and superior frontal gyri; (D) FG seed and (i) superior and medial frontal gyrus, and (ii) left middle frontal gyrus. Finally, lower FC between visual network regions and frontal cortical regions predicted worse performance on the WAIS digit-symbol coding task.

CONCLUSION

These are the first published results that directly illustrate the relationship between blast-related mTBI severity, visual pathway neural networks, and executive dysfunction - results that highlight the detrimental relationship between blast-related brain injury and the integration of visual sensory input and executive processes.

Subacute Oxidative Stress and Glial Reactivity in the Amygdala are Associated with Increased Anxiety Following Blast Neurotrauma

Behavioral symptoms, such as anxiety, are widely reported after blast overpressure (BOP) exposure. Amygdalar vulnerability to increasing magnitudes of BOP has not been investigated, and single exposures to blast have been limited to acute (<72 h) assessment. Rats were exposed to a single low, moderate, or high BOP (10, 14, or 24 psi) with an advanced blast simulator to test the susceptibility of the amygdala. Anxiety-like behavior was observed in the low- and moderate-pressure groups when subjected to the light/dark box assessment 7 days after the blast but not in high-pressure group. Immunohistochemistry was performed to measure apoptosis (cleaved caspase-3), neuronal loss (NeuN), reactive astrocytes (glial fibrillary acidic protein), microglia (Iba-1), and oxidative stress (CuZn superoxide dismutase). Slower progression of injury cascades was associated with a significant increase in anxiety, apoptosis, and astrogliosis in the low pressure group compared with others. A significant increase of CuZn superoxide dismutase in the low pressure group could be associated with neuroprotection from cell death caused by oxidative stress because neuronal loss was significant in the moderate- and high- but not the low-pressure group. Overall, this study demonstrated that overpressure as low as 10 psi can induce subacute anxiety, in addition to neuropathologic changes in the amygdala.

Preenlistment and Early Service Risk Factors for Traumatic Brain Injury in the Army and Marine Corps: FY 2002-2010

OBJECTIVE

To determine the preenlistment and early service risk factors for traumatic brain injury (TBI)-related disability in Army and Marine Corps service members.

DESIGN

Matched case-control design.

MAIN OUTCOME

TBI disability discharges.

SUBJECTS

Army and Marine Corps service members with an enlistment record and disability discharge for TBI were included as cases. Controls were selected from the enlisted population with no disability evaluation record and were matched on fiscal year of enlistment, sex, and service at a ratio of 5:1.

RESULTS

Older age at enlistment resulted in a significantly increased risk for TBI disability in the crude and adjusted models (adjusted odds ratio [aOR] = 1.49; 95% confidence interval [CI], 1.16-1.91). An enlistment military occupational specialty (MOS) with a combat arms designation resulted in an almost 3-fold increased odds of TBI disability compared with other MOS categories (aOR = 2.75; 95% CI, 2.46-3.09). This remained a significant risk factor for TBI disability in the multivariate model (aOR = 2.74; 95% CI, 2.45-3.08).

CONCLUSION

Results from this study help inform the existing body of military TBI research by highlighting the preenlistment demographic and early service risk factors for TBI disability. Further research into the role of age on TBI disability in the military is merited.

How Do Aftermath of Battle Experiences Affect Returning OEF/OIF Veterans?

Aftermath of battle experiences (ABE) may contribute to adverse mental and physical health outcomes. This study examined ABE and their effect on health functioning and posttraumatic stress disorder (PTSD) in 66 OEF/OIF/OND Veterans. Bivariate correlations were conducted to investigate the contribution of ABE to PTSD and health functioning, after controlling for combat experiences. Additionally, a mediation analyses was conducted on Role Limitations due to Emotional Problems. Results suggested that the association between ABE and Role Limitations due to Emotional Problems was mediated by PTSD. These initials findings suggest the need for more research on differences in deployment experiences.

Prospective Analysis of Premilitary Mental Health, Somatic Symptoms, and Postdeployment Postconcussive Symptoms

OBJECTIVES

Many recent studies of service members returning from deployment have focused on the health impacts of mild traumatic brain injury (mTBI), including persistent postconcussive symptoms (PCS). However, cross-sectional study designs have made it difficult to understand the role of mental health in the etiology of persistent PCS.

METHODS

Participants were 3319 military personnel (primarily men [90%] of 25-34 years [54%]) who had completed health surveys at basic training and after deployment, on average, 4.6 years later. Negative binomial regression was used to assess the association of PCS with demographic covariates, premilitary mental health and somatic symptoms, combat experiences and mTBI during deployment, in addition to postdeployment mental health and non-PCS somatic symptoms.

RESULTS

Premilitary mental health and somatic symptoms predicted PCS even when adjusting for other variables, yielding an elevated incidence rate ratio (IRR) for posttraumatic stress disorder (PTSD; IRR = 1.23, 95% confidence interval [CI] = 1.06-1.41) and somatic symptoms (mild versus minimal somatic symptoms: IRR = 1.43, 95% CI = 1.31-1.55; moderate/severe versus minimal somatic symptoms: IRR = 1.69, 95% CI = 1.43-2.06), but not for depressive symptoms. When postdeployment mental health and somatic symptom measures were added to the model, the effect of premilitary somatic symptoms remained significant.

CONCLUSIONS

Findings point to potential etiological contributions of premilitary characteristics, particularly a tendency to experience somatic symptoms and PTSD, as well as mTBI and combat experiences, to the development of PCS. PCS were also strongly related to concurrent postdeployment mental health.

Static and dynamic postural stability in veterans with combat-related mild traumatic brain injury

Persistent post-concussive symptoms are reported by 10-15% of individuals who suffer mild traumatic brain injury (mTBI), but their basis is often uncertain. One such symptom is disequilibrium, a sensation of impaired balance during standing and walking. The hypothesis for this study was that this subjective symptom is associated with objective and measurable deficits in static and dynamic postural stability. An infrared motion tracking system was used to record body motion during quiet standing and in response to waist perturbations in fourteen veterans (age 22-40 years, 13 male) of the Operations Enduring Freedom (OEF) and Iraqi Freedom (OIF), who had a history of mTBI that occurred 7 months to 7 years prior to testing. We compared body sway between veterans with mTBI reporting persistent disequilibrium (TD, n=8) and those with no vestibular symptoms (n=6), as well as to a group of non-veterans with no balance symptoms (n=10). Static postural stability was reduced in TD veterans in comparison to each of the other two groups (p<0.0002), most notably on a compliant surface with eyes closed. The TD group also had decreased dynamic stability of the upper trunk (p<0.05) and enhanced postural oscillations (p<0.02) following waist perturbations. Our findings support a physiological basis for persistent disequilibrium after mTBI and are consistent with impaired vestibular processing. Disruption of semicircular canal inputs is unlikely to be the cause, as head impulse responses were normal in all groups. The unexpected finding of dynamic postural oscillations requires further study but may indicate enhanced instability in sensorimotor networks responsible for postural control.

The Temporal Pattern of Changes in Serum Biomarker Levels Reveals Complex and Dynamically Changing Pathologies after Exposure to a Single Low-Intensity Blast in Mice

Time-dependent changes in blood-based protein biomarkers can help identify the ­pathological processes in blast-induced traumatic brain injury (bTBI), assess injury severity, and monitor disease progression. We obtained blood from control and injured mice (exposed to a single, low-intensity blast) at 2-h, 1-day, 1–week, and 1-month post-injury. We then determined the serum levels of biomarkers related to metabolism (4-HNE, HIF-1α, ceruloplasmin), vascular function (AQP1, AQP4, VEGF, vWF, Flk-1), inflammation (OPN, CINC1, fibrinogen, MIP-1a, OX-44, p38, MMP-8, MCP-1 CCR5, CRP, galectin-1), cell adhesion and the extracellular matrix (integrin α6, TIMP1, TIMP4, Ncad, connexin-43), and axonal (NF-H, Tau), neuronal (NSE, CK-BB) and glial damage (GFAP, S100β, MBP) at various post-injury time points. Our findings indicate that the exposure to a single, low-intensity blast results in metabolic and vascular changes, altered cell adhesion, and axonal and neuronal injury in the mouse model of bTBI. Interestingly, serum levels of several inflammatory and astroglial markers were either unchanged or elevated only during the acute and subacute phases of injury. Conversely, serum levels of the majority of biomarkers related to metabolic and vascular functions, cell adhesion, as well as neuronal and axonal damage remained elevated at the termination of the experiment (1 month), indicating long-term systemic and cerebral alterations due to blast. Our findings show that the exposure to a single, low-intensity blast induces complex pathological processes with distinct temporal profiles. Hence, monitoring serum biomarker levels at various post-injury time points may provide enhanced diagnostics in blast-related neurological and multi-system deficits.

Indirect associations of combat exposure with post-deployment physical symptoms in U.S. soldiers: roles of post-traumatic stress disorder, depression and insomnia

OBJECTIVE

To characterize the indirect associations of combat exposure with post-deployment physical symptoms through shared associations with post-traumatic stress disorder (PTSD), depression and insomnia symptoms.

METHODS

Surveys were administered to a sample of U.S. soldiers (N = 587) three months after a 15-month deployment to Iraq. A multiple indirect effects model was used to characterize direct and indirect associations between combat exposure and physical symptoms.

RESULTS

Despite a zero-order correlation between combat exposure and physical symptoms, the multiple indirect effects analysis did not provide evidence of a direct association between these variables. Evidence for a significant indirect association of combat exposure and physical symptoms was observed through PTSD, depression, and insomnia symptoms. In fact, 92% of the total effect of combat exposure on physical symptoms scores was indirect. These findings were evident even after adjusting for the physical injury and relevant demographics.

CONCLUSION

This is the first empirical study to suggest that PTSD, depression and insomnia collectively and independently contribute to the association between combat exposure and post-deployment physical symptoms. Limitations, future research directions, and potential policy implications are discussed.

The suppression of brain activation in post-deployment military personnel with posttraumatic stress symptoms

Previous research using cognitive paradigms has found task-related activation that includes prefrontal brain structures and that is attenuated in association with posttraumatic stress symptoms (PTSS). The present investigation used a cognitive control paradigm, the Arrows Task, to study subjects who had not sustained a traumatic brain injury during deployment and who had a wide range of scores on the Posttraumatic Stress Disorder Checklist (PCL). During the Arrows Task there was no significant activation within the full sample of 15 subjects, but deactivation was found within areas that are likely to be involved in cognitive control, including the dorsal anterior cingulate gyrus and parietal cortex. Exploratory analyses were also conducted to compare subjects with relatively high PTSS (HIGH PTSS, n = 7) to those with lower severity or no symptoms (LOW PTSS, n = 8). LOW PTSS subjects exhibited activation in nonfrontal brain areas and their activation was greater relative to the HIGH PTSS subjects. In contrast, the HIGH PTSS group had extensive deactivation and there was a negative relationship between activation and PCL scores within subcortical structures, the cerebellum, and higher-order cortical association areas. For the HIGH PTSS group there was also a positive relationship between PCL scores and activation within basic sensory and motor areas, as well as structures thought to have a role in emotion and the regulation of internal bodily states. These findings are consistent with widespread neural dysfunction in subjects with greater PTSS, including changes similar to those reported to occur with acute stress and elevated noradrenergic activity.

Cognitive changes and dementia risk after traumatic brain injury: implications for aging military personnel

Traumatic brain injury (TBI) is recognized as an important risk factor for the long-term cognitive health of military personnel, particularly in light of growing evidence that TBI increases risk for Alzheimer's disease and other dementias. In this article, we review the neurocognitive and neuropathologic changes after TBI with particular focus on the potential risk for cognitive decline across the life span in military service members. Implications for monitoring and surveillance of cognition in the aging military population are discussed. Additional studies are needed to clarify the factors that increase risk for later life cognitive decline, define the mechanistic link between these factors and dementia, and provide empirically supported interventions to mitigate the impact of TBI on cognition across the life span.

Acute post-traumatic stress symptoms and age predict outcome in military blast concussion

High rates of adverse outcomes have been reported following blast-related concussive traumatic brain injury in US military personnel, but the extent to which such adverse outcomes can be predicted acutely after injury is unknown. We performed a prospective, observational study of US military personnel with blast-related concussive traumatic brain injury (n = 38) and controls (n = 34) enrolled between March and September 2012. Importantly all subjects returned to duty and did not require evacuation. Subjects were evaluated acutely 0-7 days after injury at two sites in Afghanistan and again 6-12 months later in the United States. Acute assessments revealed heightened post-concussive, post-traumatic stress, and depressive symptoms along with worse cognitive performance in subjects with traumatic brain injury. At 6-12 months follow-up, 63% of subjects with traumatic brain injury and 20% of controls had moderate overall disability. Subjects with traumatic brain injury showed more severe neurobehavioural, post-traumatic stress and depression symptoms along with more frequent cognitive performance deficits and more substantial headache impairment than control subjects. Logistic regression modelling using only acute measures identified that a diagnosis of traumatic brain injury, older age, and more severe post-traumatic stress symptoms provided a good prediction of later adverse global outcomes (area under the receiver-operating characteristic curve = 0.84). Thus, US military personnel with concussive blast-related traumatic brain injury in Afghanistan who returned to duty still fared quite poorly on many clinical outcome measures 6-12 months after injury. Poor global outcome seems to be largely driven by psychological health measures, age, and traumatic brain injury status. The effects of early interventions and longer term implications of these findings are unknown.

Suicidal Ideation among Florida National Guard Members: Combat Deployment and Non-Deployment Risk and Protective Factors

This study examined relationships among risk/protective factors and suicidal ideation (SI) in deployed and non-deployed National Guard members, particularly examining for possible differential effects of deployment on SI. A total of 3,098 Florida National Guard members completed an anonymous online survey that assessed variables associated with SI including demographics, current psychiatric diagnoses, and pre-, during, and post-deployment experiences. Those deployed had significantly higher rates of SI (5.5%) than those not deployed (3.0%; p < .001). In multivariate analyses, among those not deployed, SI was significantly associated with major depressive disorder (p < .001), posttraumatic stress disorder (PTSD) (p < .001), prior psychological trauma (p < .01), and heavy/hazardous alcohol consumption (p < .05). In contrast, in the deployed, only PTSD (p < .001) and deployment-related mild traumatic brain injury (p < .05) were independently associated with SI. Risk and protective factors differed by deployment status in National Guard members suggesting the possible need for cohort-specific treatment targets to minimize SI.

Using information from the electronic health record to improve measurement of unemployment in service members and veterans with mTBI and post-deployment stress

OBJECTIVE

The purpose of this pilot study is 1) to develop an annotation schema and a training set of annotated notes to support the future development of a natural language processing (NLP) system to automatically extract employment information, and 2) to determine if information about employment status, goals and work-related challenges reported by service members and Veterans with mild traumatic brain injury (mTBI) and post-deployment stress can be identified in the Electronic Health Record (EHR).

DESIGN

Retrospective cohort study using data from selected progress notes stored in the EHR.

SETTING

Post-deployment Rehabilitation and Evaluation Program (PREP), an in-patient rehabilitation program for Veterans with TBI at the James A. Haley Veterans' Hospital in Tampa, Florida.

PARTICIPANTS

Service members and Veterans with TBI who participated in the PREP program (N = 60).

MAIN OUTCOME MEASURES

Documentation of employment status, goals, and work-related challenges reported by service members and recorded in the EHR.

RESULTS

Two hundred notes were examined and unique vocational information was found indicating a variety of self-reported employment challenges. Current employment status and future vocational goals along with information about cognitive, physical, and behavioral symptoms that may affect return-to-work were extracted from the EHR. The annotation schema developed for this study provides an excellent tool upon which NLP studies can be developed.

CONCLUSIONS

Information related to employment status and vocational history is stored in text notes in the EHR system. Information stored in text does not lend itself to easy extraction or summarization for research and rehabilitation planning purposes. Development of NLP systems to automatically extract text-based employment information provides data that may improve the understanding and measurement of employment in this important cohort.

Deployment-related mild traumatic brain injury, mental health problems, and post-concussive symptoms in Canadian Armed Forces personnel

BACKGROUND

Up to 20% of US military personnel deployed to Iraq or Afghanistan experience mild traumatic brain injury (mTBI) while deployed; up to one-third will experience persistent post-concussive symptoms (PCS). The objective of this study was to examine the epidemiology of deployment-related mTBI and its relationship to PCS and mental health problems (MHPs) in Canadian Armed Forces (CAF) personnel.

METHODS

Participants were 16153 personnel who underwent post-deployment screening (median =136 days after return) following deployment in support of the mission in Afghanistan from 2009 - 2012. The screening questionnaire assessed mTBI and other injuries while deployed, using the Brief Traumatic Brain Injury Screening Tool. Current MHPs and PCS were assessed using items from the Patient Health Questionnaire, the Patient Checklist for PTSD, and the Cognitive Failures Questionnaire. Log-binomial regression explored the association of mTBI, other injuries, and MHPs with PCS, using the presence of 3 or more of 7 PCS as the outcome. Results are expressed as adjusted prevalence ratios (PR).

RESULTS

mTBI while deployed was reported in 843 respondents (5.2%). Less severe forms of mTBI (associated only with having been dazed or confused or having "seen stars") predominated. Blast was reported as a mechanism of injury in half of those with mTBI. Multiple PCS were present in 21% of those with less severe forms of mTBI and in 27% of those with more severe forms of mTBI (i.e., mTBI associated with loss of consciousness or post-traumatic amnesia). After adjustment for confounding, mTBI had no statistically significant association with PCS relative to non-TBI injury. In contrast, MHPs had a strong association with reporting 3 or more PCS (adjusted prevalence ratio (PR) =7.77).

CONCLUSION

Deployment-related mTBI prevalence was lower than in many US reports; most of those who had had mTBI were free of multiple PCS. PCS was strongly associated with MHPs but not with mTBI. Careful assessment of MHPs is essential in personnel with a history of combat-related mTBI and PCS.

A multisite study of the relationships between blast exposures and symptom reporting in a post-deployment active duty military population with mild traumatic brain injury

Explosive devices have been the most frequent cause of traumatic brain injury (TBI) among deployed contemporary U.S. service members. The purpose of this study was to examine the influence of previous cumulative blast exposures (that did or did not result in TBI) on later post-concussion and post-traumatic symptom reporting after sustaining a mild TBI (MTBI). Participants were 573 service members who sustained MTBI divided into four groups by number of blast exposures (1, 2, 3, and 4-10) and a nonblast control group. Post-concussion symptoms were measured using the Neurobehavioral Symptom Inventory (NSI) and post-traumatic stress disorder (PTSD) symptoms using the Post-traumatic Checklist-Civilian version (PCL-C). Results show groups significantly differed on total NSI scores (p<0.001), where symptom endorsement increased as number of reported blast exposures increased. Total NSI scores were significantly higher for the 3- and 4-10 blast groups compared with the 1- and 2-blast groups with effect sizes ranging from small to moderate (d=0.31 to 0.63). After controlling for PTSD symptoms using the PCL-C total score, NSI total score differences remained between the 4-10-blast group and the 1- and 2-blast groups, but were less pronounced (d=0.35 and d=0.24, respectively). Analyses of NSI subscale scores using PCL-C scores as a covariate revealed significant between-blast group differences on cognitive, sensory, and somatic, but not affective symptoms. Regression analyses revealed that cumulative blast exposures accounted for a small but significant amount of the variance in total NSI scores (4.8%; p=0.009) and total PCL-C scores (2.3%; p<0.001). Among service members exposed to blast, post-concussion symptom reporting increased as a function of cumulative blast exposures. Future research will need to determine the relationship between cumulative blast exposures, symptom reporting, and neuropathological changes.

Neurobehavioral, neuropathological and biochemical profiles in a novel mouse model of co-morbid post-traumatic stress disorder and mild traumatic brain injury

Co-morbid mild traumatic brain injury (mTBI) and post-traumatic stress disorder (PTSD) has become the signature disorder for returning combat veterans. The clinical heterogeneity and overlapping symptomatology of mTBI and PTSD underscore the need to develop a preclinical model that will enable the characterization of unique and overlapping features and allow discrimination between both disorders. This study details the development and implementation of a novel experimental paradigm for PTSD and combined PTSD-mTBI. The PTSD paradigm involved exposure to a danger-related predator odor under repeated restraint over a 21 day period and a physical trauma (inescapable footshock). We administered this paradigm alone, or in combination with a previously established mTBI model. We report outcomes of behavioral, pathological and biochemical profiles at an acute timepoint. PTSD animals demonstrated recall of traumatic memories, anxiety and an impaired social behavior. In both mTBI and combination groups there was a pattern of disinhibitory like behavior. mTBI abrogated both contextual fear and impairments in social behavior seen in PTSD animals. No major impairment in spatial memory was observed in any group. Examination of neuroendocrine and neuroimmune responses in plasma revealed a trend toward increase in corticosterone in PTSD and combination groups, and an apparent increase in Th1 and Th17 proinflammatory cytokine(s) in the PTSD only and mTBI only groups respectively. In the brain there were no gross neuropathological changes in any groups. We observed that mTBI on a background of repeated trauma exposure resulted in an augmentation of axonal injury and inflammatory markers, neurofilament L and ICAM-1 respectively. Our observations thus far suggest that this novel stress-trauma-related paradigm may be a useful model for investigating further the overlapping and distinct spatio-temporal and behavioral/biochemical relationship between mTBI and PTSD experienced by combat veterans.

Diffusion tensor imaging reveals acute subcortical changes after mild blast-induced traumatic brain injury

Mild blast-induced traumatic brain injury (mbTBI) poses special diagnostic challenges due to its overlapping symptomatology with other neuropsychiatric conditions and the lack of objective outcome measures. Diffusion tensor imaging (DTI) can potentially provide clinically relevant information toward a differential diagnosis. In this study, we aimed to determine if single and repeated (5 total; administered on consecutive days) mild blast overpressure exposure results in detectable structural changes in the brain, especially in the hippocampus. Fixed rat brains were analyzed by ex vivo DTI at 2 h and 42 days after blast (or sham) exposure(s). An anatomy-based region of interest analysis revealed significant interactions in axial and radial diffusivity in a number of subcortical structures at 2 h only. Differences between single- and multiple-injured rats were largely in the thalamus but not the hippocampus. Our findings demonstrate the value and the limitations of DTI in providing a better understanding of mbTBI pathobiology.

Nurses' knowledge of pain management for patients with combat-related traumatic brain injuries on rehabilitation units

PURPOSE

The purpose of this project was to survey nurses' knowledge of pain management for patients with combat-related traumatic brain injuries (TBI).

DESIGN/METHODS

A survey was used to collect data regarding nurses' knowledge of pain assessment and management for patients with combat-related TBI. Nurses were invited to participate in the study via email and provided with a link to the electronic survey.

FINDINGS

Twenty-five surveys were returned (52% response rate). A total of 76% of nurse respondents perceived that TBI patients over report pain intensity. Only 40% of nurses were able to correctly identify the appropriate medication to treat migraine-type headache pain in TBI patients.

CONCLUSION

This study identified gaps in knowledge regarding pain management for patients with combat related TBIs.

CLINICAL RELEVANCE

Nurses need additional education regarding common pain syndromes, available treatments, and a better understanding of addiction in order to provide optimal care to these patients.

Hyperbaric oxygen for blast-related postconcussion syndrome: three-month outcomes

OBJECTIVE

Mild traumatic brain injury (mTBI) and postconcussion syndrome (PCS) are common among military combatants. Hyperbaric oxygen (HBO2 ) is a proposed treatment for these conditions, but it has not been rigorously studied. The objective of this study was to determine the effects of HBO2 by 3 months post compression at 2 commonly employed dosing levels to treat PCS; whether specific subgroups may have benefited; and if no overall effect was found, whether benefit is masked by other conditions.

METHODS

This randomized, double-blind, sham-controlled study was conducted at the Naval Air Station in Pensacola, Florida on 61 male Marines with a history of mTBI and PCS. Intervention consisted of 40 once daily 60-minute hyperbaric chamber compressions at 2.0 atmospheres absolute (ATA) at 1 of 3 randomly preassigned oxygen fractions, resulting in respective blinded groups with an oxygen-breathing exposure equivalent to (1) surface air (sham), (2) 100% oxygen at 1.5ATA, or (3) 100% oxygen at 2.0ATA. The main outcome measure was the Rivermead Post-Concussion Questionnaire-16 (RPQ-16) collected before compressions and at 2 later points.

RESULTS

The interaction of time by intervention group was not significant for improvement on the RPQ-16. Nor was there evidence of efficacy on the RPQ-16 for any subgroup. No significant time by intervention interaction was found for any functional, cognitive, or psychomotor secondary outcome measure at an unadjusted 0.05 significance level.

INTERPRETATION

Using a randomized control trial design and analysis including a sham, results showed no evidence of efficacy by 3 months post-compression to treat the symptomatic, cognitive, or behavioral sequelae of PCS after combat-related mTBI.

Blast neurotrauma impairs working memory and disrupts prefrontal myo-inositol levels in rats

Working memory, which is dependent on higher-order executive function in the prefrontal cortex, is often disrupted in patients exposed to blast overpressure. In this study, we evaluated working memory and medial prefrontal neurochemical status in a rat model of blast neurotrauma. Adult male Sprague-Dawley rats were anesthetized with 3% isoflurane and exposed to calibrated blast overpressure (17 psi, 117 kPa) while sham animals received only anesthesia. Early neurochemical effects in the prefrontal cortex included a significant decrease in betaine (trimethylglycine) and an increase in GABA at 24 h, and significant increases in glycerophosphorylcholine, phosphorylethanolamine, as well as glutamate/creatine and lactate/creatine ratios at 48 h. Seven days after blast, only myo-inositol levels were altered showing a 15% increase. Compared to controls, short-term memory in the novel object recognition task was significantly impaired in animals exposed to blast overpressure. Working memory in control animals was negatively correlated with myo-inositol levels (r=-.759, p<0.05), an association that was absent in blast exposed animals. Increased myo-inositol may represent tardive glial scarring in the prefrontal cortex, a notion supported by GFAP changes in this region after blast overexposure as well as clinical reports of increased myo-inositol in disorders of memory.

Functional status after blast-plus-impact complex concussive traumatic brain injury in evacuated United States military personnel

Fundamental questions remain unanswered about the longitudinal impact of blast-plus-impact complex traumatic brain injuries (TBI) from wars in Iraq and Afghanistan. This prospective, observational study investigated measures of clinical outcome in US military personnel evacuated to Landstuhl Regional Medical Center (LRMC) in Germany after such "blast-plus" concussive TBIs. Glasgow Outcome Scale-Extended assessments completed 6-12 months after injury indicated a moderate overall disability in 41/47 (87%) blast-plus TBI subjects and a substantial but smaller number (11/18, 61%, p=0.018) of demographically similar US military controls without TBI evacuated for other medical reasons. Cognitive function assessed with a neuropsychological test battery was not different between blast-plus TBI subjects and controls; performance of both groups was generally in the normal range. No subject was found to have focal neurological deficits. However, 29/47 (57%) of blast-plus subjects with TBI met all criteria for post-traumatic stress disorder (PTSD) versus 5/18 (28%) of controls (p=0.014). PTSD was highly associated with overall disability; 31/34 patients with PTSD versus 19/31 patients who did not meet full PTSD criteria had moderate to severe disability (p=0.0003). Symptoms of depression were also more severe in the TBI group (p=0.05), and highly correlated with PTSD severity (r=0.86, p<0.0001). Thus, in summary, high rates of PTSD and depression but not cognitive impairment or focal neurological deficits were observed 6-12 months after concussive blast-plus-impact complex TBI. Overall disability was substantially greater than typically reported in civilian non-blast concussive ("mild") patients with TBI, even with polytrauma. The relationship between these clinical outcomes and specific blast-related aspects of brain injuries versus other combat-related factors remains unknown.