Convergent and Discriminant Validity of the Blast Exposure Threshold Survey in United States Military Service Members and Veterans.

The Blast Exposure Threshold Survey (BETS) is a recently developed and promising new self-report measure of lifetime blast exposure (LBE). However, there are no studies that have examined the psychometric properties of the BETS, which currently limits its clinical utility. The purpose of this study was to examine the convergent and discriminant validity of the BETS by comparing the BETS Generalized Blast Exposure Value (GBEV) to six variables hypothesized to be associated with LBE (i.e., single-item LBE, combat exposure, years in the military, number of combat deployments, and military occupation specialty [MOS]) and three variables hypothesized not to be associated with LBE (i.e., age at the time of injury, estimated pre-morbid Full-Scale Intelligence Quotient [FSIQ], and resilience). Participants were 202 United States service members and veterans prospectively enrolled from three military medical treatment facilities (68.7%) and via community recruitment initiatives (31.3%). Participants completed the BETS, Combat Exposure Scale (CES), Deployment Risk and Resiliency Inventory-2 Combat Experiences (DRRI-2 CE), Traumatic Brain Injury-Quality of Life Resilience scale, and a brief structured interview. For some analyses, participants were classified into two blast risk MOS groups: high (n = 89) and low (n = 94). The BETS GBEV was not significantly correlated with all three non-blast related variables (rs = 0.01 to rs = -0.12). In contrast, GBEV was significantly (p < 0.001) associated with all blast-related variables; single-item LBE (rs = 0.76), CES (rs = 0.58), number of combat deployments (rs = 0.53), DRRI-2 CE (rs = 0.48), and high blast risk MOS (r = 0.36, medium effect size). However, a stronger relationship was found between the blast-related variables and three modified GBEV scores when excluding some small weapons categories; single-item LBE (rs = 0.80-0.82), CES (rs = 0.64-0.67), number of combat deployments (rs = 0.56), DRRI-2 CE (rs = 0.51-0.53), and high blast risk MOS (r = 0.42-0.49, medium-large effect size). This is the first study to examine the psychometric properties of the BETS. Overall, these results offer support for the convergent and discriminant validity of the BETS. In order to ensure that the BETS can be confidently used as a valid and reliable measure of LBE, more research is needed to further examine the psychometric properties of the test, particularly with regard to the establishment of test-retest reliability.

White Matter Organization and Cortical Thickness Differ Among Active Duty Service Members With Chronic Mild, Moderate, and Severe Traumatic Brain Injury.

Abstract This study compared findings from whole-brain diffusion tensor imaging (DTI) and volumetric magnetic resonance imaging (MRI) among 90 Active Duty Service Members with chronic mild traumatic brain injury (TBI; n = 52), chronic moderate-to-severe TBI (n = 17), and TBI-negative controls (n = 21). Data were collected on a Philips Ingenia 3T MRI with DTI in 32 directions. Results demonstrated that history of TBI was associated with differences in white matter microstructure, white matter volume, and cortical thickness in both mild TBI and moderate-to-severe TBI groups relative to controls. However, the presence, pattern, and distribution of these findings varied substantially depending on the injury severity. Spatially-defined forms of DTI fractional anisotropy (FA) analyses identified altered white matter organization within the chronic moderate-to-severe TBI group, but they did not provide clear evidence of abnormalities within the chronic mild TBI group. In contrast, DTI FA "pothole" analyses identified widely distributed areas of decreased FA throughout the white matter in both the chronic mild TBI and chronic moderate-to-severe TBI groups. Additionally, decreased white matter volume was found in several brain regions for the chronic moderate-to-severe TBI group compared with the other groups. Greater number of DTI FA potholes and reduced cortical thickness were also related to greater severity of self-reported symptoms. In sum, this study expands upon a growing body of literature using advanced imaging techniques to identify potential effects of brain injury in military Service Members. These findings may differ from work in other TBI populations due to varying mechanisms and frequency of injury, as well as a potentially higher level of functioning in the current sample related to the ability to maintain continued Active Duty status after injury. In conclusion, this study provides DTI and volumetric MRI findings across the spectrum of TBI severity. These results provide support for the use of DTI and volumetric MRI to identify differences in white matter microstructure and volume related to TBI. In particular, DTI FA pothole analysis may provide greater sensitivity for detecting subtle forms of white matter injury than conventional DTI FA analyses.

The Impact of Lifetime Traumatic Brain Injury (TBI) on Mental Health Symptoms among Service Members in Interdisciplinary TBI Programs.

INTRODUCTION: Traumatic brain injury (TBI) is highly prevalent among active duty service members (ADSMs) and imposes a significant health burden, particularly on mental health (e.g., post-traumatic stress disorder [PTSD] and depressive symptoms). Little is known about how TBI setting characteristics impact PTSD and depressive symptom expression in service members undergoing interdisciplinary TBI care. MATERIALS AND METHODS: The study included 455 patients enrolled in interdisciplinary, outpatient TBI programs within the military health system. Using Poisson regression with robust error variance, TBI injury setting characteristics (i.e., before military service, during military training, and during noncombat/combat deployment) were evaluated against clinically-elevated PTSD (PTSD Checklist, DSM-5 score ≥ 33) and depressive (Patient Health Questionnaire-8 score ≥ 15) symptoms. RESULTS: In adjusted models, TBI sustained before military service was associated with less likelihood for clinically-elevated PTSD symptoms at pretreatment (prevalence ratio [PR] = 0.76, confidence interval [CI] = 0.60-0.96) and post-treatment (PR = 0.67, CI = 0.52-0.87). TBI sustained during combat deployment, however, resulted in the greatest impact on clinically-elevated pretreatment PTSD (PR = 1.49, CI = 1.16-1.91) and depressive (PR = 1.47, CI = 1.06-2.03) symptoms. Null results were found between military training/noncombat deployment and mental health symptoms. Regardless of the TBI setting, following TBI treatment, there remained 37.5% (n = 180) and 24.8% (n = 108) with clinically-elevated PTSD and depressive symptoms, respectively. CONCLUSIONS: There was a differential impact of TBI settings, particularly between TBI sustained before military service and that from combat deployment among ADSMs enrolled in outpatient TBI programs. This may be indicative of differences in the characteristics of these environments (e.g., injury severity) or the impact of such an event during recovery from current TBIs. The large percentage of ADSMs who present with clinically-elevated mental health symptoms after treatment may suggest the need for additional resources to address mental health needs before, during, and after treatment in TBI programs.

Identifying Unique Symptom Groups Following Mild Traumatic Brain Injury Using the Neurobehavioral Symptom Inventory and PTSD Checklist-5 in Military Personnel: A Bifactor Analysis.

OBJECTIVE: To identify both shared and unique groups of posttraumatic stress and postconcussive symptoms using bifactor analysis. SETTING: Two large military outpatient traumatic brain injury (TBI) rehabilitation clinics in the Southwestern United States. PARTICIPANTS: A sample of 1476 Active Duty Service Members seeking treatment for a mild TBI sustained more than 30 days previously, without history of moderate or severe TBI, who completed measures of postconcussive and posttraumatic stress symptoms assessed at clinic intake. DESIGN: Observational, correlational study with data taken from an institutional review board-approved clinical registry study. MAIN MEASURES: Neurobehavioral Symptom Inventory (NSI) and Posttraumatic Stress Disorder (PTSD) Checklist for Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) ( DSM-V ) (PCL-5). Concurrent measures were Patient Health Questionnaire (PHQ-8), Pittsburgh Sleep Quality Index (PSQI), and Headache Impact Test (HIT-6). RESULTS: Results identified a bifactor model demonstrating unique posttraumatic stress, depressive, cognitive, and neurological/somatic symptom groups that were still evident after accounting for a universal factor representing general distress. These symptom groups were differentially related to concurrently measured clinical outcomes. CONCLUSION: Use of a bifactor structure may help derive clinically useful signals from self-reported symptoms among Active Duty Service Members seeking outpatient treatment for mild TBI.

Clinical utility of PTSD, resilience, sleep, and blast as risk factors to predict poor neurobehavioral functioning following traumatic brain injury: A longitudinal study in U.S. military service members.

PURPOSE: This study examined the clinical utility of post-traumatic stress disorder (PTSD), low resilience, poor sleep, and lifetime blast exposure as risk factors for predicting future neurobehavioral outcome following traumatic brain injury (TBI). METHODS: Participants were 591 U.S. military service members and veterans who had sustained a TBI (n = 419) or orthopedic injury without TBI (n = 172). Participants completed the Neurobehavioral Symptom Inventory, PTSD Checklist, and the TBI-Quality of Life (TBI-QOL) scale at baseline and follow-up. RESULTS: Using the four risk factors at baseline, 15 risk factor combinations were examined by calculating odds ratios to predict poor neurobehavioral outcome at follow-up (i.e., number of abnormal scores across five TBI-QOL scales [e.g., Fatigue, Depression]). The vast majority of risk factor combinations resulted in odds ratios that were considered to be clinically meaningful (i.e., ≥ 2.5) for predicting poor outcome. The risk factor combinations with the highest odds ratios included PTSD singularly, or in combination with poor sleep and/or low resilience (odds ratios = 4.3-72.4). However, poor sleep and low resilience were also strong predictors in the absence of PTSD (odds ratios = 3.1-29.8). CONCLUSION: PTSD, poor sleep, and low resilience, singularly or in combination, may be valuable risk factors that can be used clinically for targeted early interventions.

Presenting symptoms as prognostic measures of mental health recovery among service members with concussion.

Background: Comorbid mental illness may negatively impact recovery from concussion. This study evaluated whether the level of symptom clusters at clinic intake contribute to poor mental health recovery in concussed patients during treatment, which may in turn serve as a target intervention. Objective: The objective of this study is to examine the association between the level of initial symptoms and mental health symptoms among service members with concussion. Methods: Data were obtained from 483 active duty service members treated in interdisciplinary treatment programs for traumatic brain injury, all of which were concussions. Pre-treatment symptom clusters included self-reported hyperarousal, dissociation/depression, cognitive dysfunction/headache and neurological symptoms. The outcomes, clinically-relevant decreases in depressive symptoms (assessed by the 8-item Patient Health Questionnaire, PHQ-8) and PTSD symptoms (assessed by the PTSD Checklist for DSM-5, PCL-5), were defined as a decrease in PHQ-8 > 5 and PCL-5 > 7, respectively. Poisson regression with robust error variance was used to evaluate the relationship between the level of each symptom cluster and clinically-relevant decrease in outcomes. Results: Participants with higher (vs. lower) levels of pre-treatment hyperarousal and dissociation/depression symptom cluster were less likely to improve in depressive and PTSD symptoms during treatment. The level of cognitive/headache and neurological symptom clusters were not significantly associated with any symptom changes. Conclusion: These findings support the need for individualized treatment for symptoms identified and treated after determining concussion history, with particular attention to high levels of hyperarousal and dissociation/depression prior to treatment.

Disparities in mental health symptoms recovery across race/ethnicity and education level following mild traumatic brain injury.

Purpose: The purpose of this study was to investigate the relationship between race/ethnicity and post-concussive mental health (i.e., depressive, post-traumatic stress disorder [PTSD]) and neurobehavioral symptoms among service members, and whether this association differed by education level. Methods: The study sample consisted of 524 patients from a multidisciplinary US military outpatient treatment facility for post-concussive symptoms. Poisson regression with robust error variance was utilized to investigate outcome (i.e., clinically-elevated depressive [Patient Health Questionnaire-8 ≥15], PTSD [PTSD Checklist, DSM 5 ≥38] and neurobehavioral [Neurobehavioral Symptom Inventory >75th percentile] symptoms at admission and last follow-up in this cohort study. Modification by education level (low [no college degree] vs. high [associate's degree or higher]) was additionally evaluated. Results: The relationship between race/ethnicity and mental health/neurobehavioral symptoms varied by education level (p-interaction: depressive symptoms = 0.002, PTSD symptoms = 0.035, neurobehavioral symptoms = 0.040). Specifically, non-Whites were at a significantly higher prevalence for clinically-elevated depressive symptoms post-treatment than Whites, but only among those with higher education level (PR = 2.22, CI = 1.37-3.59). A similar trend was demonstrated for PTSD and neurobehavioral symptoms. Conclusion: Military healthcare may need to increase depression-focused treatment options that are acceptable for racial/ethnic minority patients, particularly those with higher education, while they are recovering from comorbid traumatic brain injury.

Multimodal Neurocognitive Screening of Military Personnel With a History of Mild Traumatic Brain Injury Using the Bethesda Eye & Attention Measure.

OBJECTIVE: To evaluate a neurocognitive eye tracking task, the Bethesda Eye & Attention Measure (BEAM), for use in cognitive screening of patients with a history of mild traumatic brain injury (TBI). SETTING: US military TBI rehabilitation clinic. DESIGN/PARTICIPANTS: Cross-sectional study of 191 military personnel receiving outpatient services related to history of mild TBI. Main measures: BEAM; neuropsychological screening measures of attention, processing speed, executive function, and memory. RESULTS: Medium effect sizes were found for partial correlations (controlling for age) between key BEAM metrics and neuropsychological screening tests. Linear regression analyses demonstrated that BEAM saccadic eye movements and manual (button press) metrics each provided complementary value in measurement of cognitive performance, above and beyond effects of demographic factors and clinical characteristics. CONCLUSION: This study provides initial support for the use of BEAM neurocognitive eye tracking in cognitive screening of adults with a history of mild TBI. BEAM saccadic metrics appear to be particularly well-suited for the assessment of visual attention. Study findings also highlight opportunities for greater cognitive sensitivity or testing efficiency that may be missed by tests measuring only one response modality at a time.

Intracranial Abnormalities Are Associated With Fewer Self-Reported Symptoms in Military Service Members Following Moderate-to-Severe Traumatic Brain Injury.

OBJECTIVE: This study examined the relationship between intracranial abnormalities (ICAs) and self-reported neurobehavioral and posttraumatic stress (PTS) symptoms in members of the military with moderate-to-severe traumatic brain injury (msTBI). METHOD: Participants included 539 members of the US military with nonpenetrating msTBI. Self-reported neurobehavioral and PTS symptoms were assessed using the Neurobehavioral Symptom Inventory and the PTSD Checklist-Civilian Version. ICAs were categorized as present/absent (by subtype) based upon medical record review. Spearman rank-order correlations and stepwise multiple regression analyses examined univariate and combined predictive relationships between ICAs and self-reported symptoms. RESULTS: The presence of any ICA was associated with reduced self-reported neurobehavioral and PTS symptoms. ICA-associated reductions were largest for PTS, followed by affective and cognitive neurobehavioral symptoms, and relatively weak for somatic/sensory and vestibular symptoms. Effects of different types of ICAs were comparable. Greater time since injury was related to greater symptom report, whereas duration of loss of consciousness and posttraumatic amnesia were not consistently related to self-reported symptoms. CONCLUSIONS: Results suggest that ICAs are associated with suppression of reported PTS and neurobehavioral symptoms-potentially via reduction in self-awareness. These findings support comprehensive, objective evaluation to identify impairments in self-awareness and functioning in msTBI patients.

Saccadic impairment in chronic traumatic brain injury: examining the influence of cognitive load and injury severity.

OBJECTIVE: Previous research suggests that saccadic eye movements can be uniquely sensitive to impairment in chronic traumatic brain injury (TBI). This study was conducted to examine saccadic eye movements across varying levels of cognitive load and TBI history/severity. We hypothesized that saccadic impairment in chronic mild and moderate-severe TBI would be most pronounced under conditions of high cognitive load. METHODS: In total, 61 participants (including n = 20 with chronic mild TBI, n = 15 with chronic moderate-severe TBI, and 26 uninjured controls) completed a battery of conventional neuropsychological tests and the Fusion n-Back Test, which measures manual and saccadic response time (RT) across varying cognitive load and cueing conditions. RESULTS: Consistent with our hypotheses, chronic mild and moderate-severe TBI were associated with substantial saccadic impairment under conditions of high cognitive load. Participants with moderate-severe TBI also demonstrated saccadic impairment at low levels of cognitive load. TBI groups and uninjured controls did not differ significantly on manual metrics or conventional neuropsychological measures. CONCLUSIONS: This study provides additional support for the value of eye tracking for enhanced assessment of TBI. Additionally, findings suggest that TBI is associated with greatest susceptibility to oculomotor interference under high levels of cognitive load.

An Examination of the Word Memory Test as a Measure of Memory.

This study examined the utility of the Word Memory Test (WMT) as a measure of verbal episodic memory by comparing select WMT subtests to the California Verbal Learning Test (CVLT) First and Second Editions (CVLT-II) across two samples. Correlations between the WMT and CVLT/CVLT-II subtests were statistically significant in the expected direction. Effect sizes were examined to assess the degree to which the WMT memory subtests and the CVLT First Edition subtests discriminated between groups of people who would be expected to differ from each other in verbal memory abilities. Comparison groups included cases of mild, moderate, and severe traumatic brain injury, mixed neurological patients, healthy adult controls, and patients with possible early dementia. Once invalid data were removed by studying only those who passed performance validity testing, it was found that the effect sizes between these groups were comparable. The WMT, CVLT, and CVLT-II were found to discriminate to about the same degree between people differing from each other in age, intelligence levels, and gender. Based on these data from a total sample of more than 3,000 cases, it is concluded that select WMT subtests are commensurate with the CVLT subtests as measures of memory within primarily disability-seeking samples.