Risk Factors for Postconcussion Symptom Reporting after Traumatic Brain Injury in U.S. Military Service Members

Identifying and Predicting Subgroups of Veterans With Mild Traumatic Brain Injury Based on Distinct Configurations of Postconcussive Symptom Endorsement: A Latent Class Analysis

OBJECTIVE

To identify distinct subgroups of veterans with mild traumatic brain injury (mTBI) based on configurations of postconcussive symptom (PCS) endorsement, and to examine predictors of subgroup membership.

SETTING

Outpatient Veterans Health Administration (VHA).

PARTICIPANTS

Veterans with clinician-confirmed mTBI who completed the Neurobehavioral Symptom Inventory (NSI), determined using the Comprehensive Traumatic Brain Injury Evaluation database. Individuals who tended to overreport symptoms were excluded via an embedded symptom validity scale.

DESIGN

Retrospective cohort study leveraging national VHA clinical data from 2012 to 2020. Latent class analysis (LCA) with a split-sample cross-validation procedure was used to identify subgroups of veterans. Multinomial logistic regression was used to examine predictors of subgroup membership.

MAIN MEASURES

Latent classes identified using NSI items.

RESULTS

The study included 72 252 eligible veterans, who were primarily White (73%) and male (94%). The LCA supported 7 distinct subgroups of veterans with mTBI, characterized by diverging patterns of risk for specific PCS across vestibular (eg, dizziness), somatosensory (eg, headache), cognitive (eg, forgetfulness), and mood domains (eg, anxiety). The most prevalent subgroup was Global (20.7%), followed by Cognitive-Mood (16.3%), Headache-Cognitive-Mood (H-C-M; 16.3%), Headache-Mood (14.2%), Anxiety (13.8%), Headache-Sleep (10.3%), and Minimal (8.5%). The Global class was used as the reference class for multinomial logistic regression because it was distinguished from others based on elevated risk for PCS across all domains. Female (vs male), Black (vs White), and Hispanic veterans (vs non-Hispanic) were less likely to be members of most subgroups characterized by lesser PCS endorsement relative to the Global class (excluding Headache-Mood).

CONCLUSION

The 7 distinct groups identified in this study distill heterogenous patterns of PCS endorsement into clinically actionable phenotypes that can be used to tailor clinical management of veterans with mTBI. Findings reveal empirical support for potential racial, ethnic, and sex-based disparities in PCS among veterans, informing efforts aimed at promoting equitable recovery from mTBI in this population.

Validity and Responsiveness of the Portable Warrior Test of Tactical Agility After Rehabilitation in Service Members With Mild Traumatic Brain Injury

OBJECTIVE

The Portable Warrior Test of Tactical Agility (POWAR-TOTAL) is a performance-based test designed to assess active-duty service members diagnosed with mild traumatic brain injuries (mTBIs) and could potentially inform return to duty decisions. To examine the validity and responsiveness of the POWAR-TOTAL measure, this study collected self-reported and performance measures by active-duty service members before and after an episode of physical therapist care.

METHODS

Seventy-four individuals, enrolled in care for mTBI symptoms at 1 of 2 concussion specialty Intrepid Spirit Centers, were examined the week that they initiated physical therapy with the intention to return to active duty. Self-reported measures of concussion symptoms, pain, posttraumatic stress, headache, dizziness, and sleep quality were used, as were concurrent measures of mobility and balance. The POWAR-TOTAL task (motor and cognitive skills in single and dual-task conditions) was administered. Forty-nine active-duty service members returned for posttherapy testing using the same test battery. Effect sizes for change in measures were calculated. Construct validity was assessed by correlating change scores on POWAR with concurrent self-report and mobility measures. Responsiveness was evaluated using an anchor-based approach.

RESULTS

Significant improvements in self-reported and performance-based measures, including POWAR, were observed after therapy with moderate to large effect sizes. Improvement in POWAR performance correlated with improvement in both performance and self-reported measures. After therapy, individuals who registered improvement on the Patient Global Impression of Change scale demonstrated significantly faster POWAR motor performance than those who rated little or no improvement in their condition.

CONCLUSION

The POWAR-TOTAL captured improvement on a military-specific task after completing physical therapy for mTBI and could serve as an indicator of physical recovery and readiness for return to duty.

IMPACT

Challenging cognitive and motor measures for service members may aid in the assessment of recovery and the ability to successfully return to duty after concussion as part of a comprehensive examination approach.

An Examination of Racial/Ethnic Differences on the Neurobehavioral Symptom Inventory Among Veterans Completing the Comprehensive Traumatic Brain Injury Evaluation: A Veterans Affairs Million Veteran Program Study

OBJECTIVE

The purpose of this study was to explore racial/ethnic differences in neurobehavioral symptom reporting and symptom validity testing among military veterans with a history of traumatic brain injury (TBI).

METHOD

Participants of this observational cross-sectional study (N = 9,646) were post-deployed Iraq-/Afghanistan-era veterans enrolled in the VA's Million Veteran Program with a clinician-confirmed history of TBI on the Comprehensive TBI Evaluation (CTBIE). Racial/ethnic groups included White, Black, Hispanic, Asian, Multiracial, Another Race, American Indian or Alaska Native, and Native Hawaiian or Other Pacific Islander. Dependent variables included neurobehavioral symptom domains and symptom validity assessed via the Neurobehavioral Symptom Inventory (NSI) and Validity-10, respectively.

RESULTS

Chi-square analyses showed significant racial/ethnic group differences for vestibular, somatic/sensory, and affective symptoms as well as for all Validity-10 cutoff scores examined (≥33, ≥27, ≥26, >22, ≥22, ≥13, and ≥7). Follow-up analyses compared all racial/ethnic groups to one another, adjusting for sociodemographic- and injury-related characteristics. These analyses revealed that the affective symptom domain and the Validity-10 cutoff of ≥13 revealed the greatest number of racial/ethnic differences.

CONCLUSIONS

Results showed significant racial/ethnic group differences on neurobehavioral symptom domains and symptom validity testing among veterans who completed the CTBIE. An enhanced understanding of how symptoms vary by race/ethnicity is vital so that clinical care can be appropriately tailored to the unique needs of all veterans. Results highlight the importance of establishing measurement invariance of the NSI across race/ethnicity and underscore the need for ongoing research to determine the most appropriate Validity-10 cutoff score(s) to use across racially/ethnically diverse veterans.

Exploring the Association between Personality Traits, Symptom Burden, and Return to Work after Mild-to-Moderate Traumatic Brain Injury

Approximately 30% of individuals with mild traumatic brain injury (mTBI) experience persistent post-concussion symptoms (PPCS). Personality factors have been linked to PPCS, yet, the association between personality traits and outcomes after mTBI is poorly understood. The aim of this study was to evaluate the association between personality traits, PPCS, and return to work (RTW) in patients with mild-to-moderate traumatic brain injury (TBI). Data from eighty-seven participants with mild-to-moderate TBI were analyzed. Sociodemographic, injury, and work characteristics and depressive symptoms were recorded 2-3 months post-injury. Personality traits were measured using the NEO Five-Factor Inventory-3. PPCS and RTW were assessed 15 months post-injury. Multiple linear regression models were performed. The factors associated with more severe PPCS were female sex, higher levels of neuroticism, openness to experience and conscientiousness, extra-cranial injuries, and depressive symptoms. The factors associated with lower RTW were female sex, higher levels of neuroticism, and conscientiousness. However, after controlling for PPCS, personality traits were no longer significantly associated with RTW. In conclusion, specific personality traits were associated with more severe PPCS and may be indirectly associated with RTW via PPCS. Hence, personality traits may be important to assess to identify patients at risk of less favorable outcomes after mild-to-moderate TBI.

Characteristics of Responders and Nonresponders in a Military Postconcussion Rehabilitation Program

OBJECTIVE

To characterize treatment responders and nonresponders as measured by the Neurobehavioral Symptom Inventory (NSI) in order to understand whether certain traits in our patient population would characterize favorable response.

SETTING

Brain Injury Rehabilitation Service at Brooke Army Medical Center, Fort Sam Houston, San Antonio, Texas.

PATIENTS

In total, 655 active duty military patients with a diagnosis of mild traumatic brain injury (mTBI) who received treatment between 2007 and 2020 and completed self-report measures as part of routine care.

DESIGN

Observational retrospective analysis of outpatient clinical outcomes data.

MAIN MEASURES

The primary outcome measure was the NSI, divided into the responder and nonresponder groups. Responders were defined by reliable change in NSI total score (decrease of ≥8 points from intake to discharge).

FINDINGS

Responders (n = 395) reported a higher level of symptom burden at intake on the NSI. Women responded proportionally more (70%) than men (58%). After treatment, responders reported improvements on all measures evaluated while nonresponders reported no change or slightly worse symptoms. Logistic regression analysis showed that posttraumatic stress symptoms at intake decreased odds of favorable treatment response while satisfaction with social relationships increased odds of favorable treatment response.

CONCLUSION

The results from this process improvement project suggested that posttraumatic symptoms warrant programmatic attention in TBI clinics while social relationships may be a protective factor that can be capitalized to enhance troop readiness. Systematic examination of these characteristics should be conducted on a larger population within the military health system.

Personality Characteristics and Acute Symptom Response Predict Chronic Symptoms After Mild Traumatic Brain Injury

OBJECTIVE

Despite consensus that personality influences mild traumatic brain injury (mTBI) recovery, it has been underexamined. We evaluated the extent to which diverse personality and psychiatric symptom dimensions predict mTBI recovery.

METHODS

This prospective cohort study involved psychological assessments of hospital patients with mTBI (n = 75; median = 2 days post-injury, range = 0-12 days) and orthopedic trauma controls (OTC; n = 79) who were used for comparison in mediation modeling. Chronic symptoms were evaluated at 3 months after mTBI (n = 50) using the Sport Concussion Assessment Tool (SCAT) symptom checklist. Linear regression analyses were used to identify the predominant predictors of chronic symptoms in mTBI. Modern mediation analyses tested the hypothesis that personality traits predict chronic symptoms through acute psychological response to injury.

RESULTS

In mTBI, trait psychoticism directly predicted chronic mTBI symptoms and was the strongest personality predictor overall. Furthermore, an internalizing personality dimension emphasizing negative affect/emotionality and detachment predicted chronic mTBI symptoms indirectly through enhancement of acute somatic complaints. In OTC, internalizing personality acted through the same mediator as in mTBI, whereas the effect of psychoticism was also mediated through acute somatic complaints. There was varying support for a moderated direct effect of personality traits at low levels of positive emotionality across models.

CONCLUSION

These causal models provide novel insights about the role of personality in mTBI symptom recovery, highlighting the complexity of how psychological processes may interact to affect recovery and revealing that some of these processes may be non-specific to brain injury.

Network Analysis of Research on Mild Traumatic Brain Injury in US Military Service Members and Veterans During the Past Decade (2010-2019)

OBJECTIVE

To evaluate trends in the extant literature on mild traumatic brain injury (mTBI) in military service members and veterans using network analysis based on a comprehensive search of original, peer-reviewed research articles involving human participants published between January 1, 2010, and December 31, 2019. Specifically, we employed network analysis to evaluate associations in the following areas: (1) peer-reviewed journals, (2) authors, (3) organizations/institutions, and (4) relevant key words.

PARTICIPANTS

Included studies were published in peer-reviewed journals available on Web of Science database, using US military service members or veterans.

DESIGN

Bibliometric network analytical review.

MAIN MEASURES

Outcomes for each analysis included number of articles, citations, total link strength, and clusters.

RESULTS

The top publishing journals were (1) Journal of Head Trauma and Rehabilitation, (2) Military Medicine, (3) Brain Injury, (4) Journal of Neurotrauma, and (5) Journal of Rehabilitation Research and Development. The top publishing authors were (1) French, (2) Lange, (3) Cooper, (4) Vanderploeg, and (5) Brickell. The top research institutions were (1) Defense and Veterans Brain Injury Center, (2) Uniformed Services University of the Health Sciences, (3) University of California San Diego, (4) Walter Reed National Military Medical Center, and (5) Boston University. The top co-occurring key words in this analysis were (1) posttraumatic stress disorder (PTSD), (2) persistent postconcussion symptoms (PPCS), (3) blast injury, (4) postconcussion syndrome (PCS), and (5) Alzheimer's disease.

CONCLUSIONS

The results of this network analysis indicate a clear focus on veteran health, as well as investigations on chronic effects of mTBI. Research in civilian mTBI indicates that delaying treatment for symptoms and impairments related to mTBI may not be the most precise treatment strategy. Increasing the number of early, active, and targeted treatment trials in military personnel could translate to meaningful improvements in clinical practices for managing mTBI in this population.

Patient Attribution of Posttraumatic Symptoms to Brain Injury Versus PTSD in Military-Related Mild TBI

OBJECTIVE

Persistent cognitive, somatic, and neuropsychiatric symptoms following mild traumatic brain injury (TBI) are influenced by posttraumatic stress disorder (PTSD), particularly in military patients. The authors evaluated the degree to which military service members with a history of mild TBI attributed posttraumatic symptoms to TBI versus PTSD.

METHODS

Service members (N=372) with mild TBI were surveyed about the severity of posttraumatic symptoms across four symptom clusters (cognitive, affective, somatosensory, and vestibular) with the Neurobehavioral Symptom Inventory (NSI). Participants rated the degree to which they believed TBI, PTSD, or other conditions contributed to their symptoms. Differences in cognitive, affective, somatosensory, and vestibular symptom severity were evaluated across participants with TBI, PTSD, or combined TBI-PTSD attribution. Logistic regression was used to evaluate the association between symptom profiles and attribution.

RESULTS

Participants attributed symptoms mostly to TBI, followed by insufficient sleep, PTSD, chronic pain, depression, and deployment-readjustment stress. PTSD and combined TBI-PTSD attribution were associated with higher total NSI scores (39.5 and 51.6, respectively), compared with TBI attribution only (31.4) (F=29.08, df=3, 358, p<0.01), as well as higher scores in every symptom category. More severe affective symptoms were associated with decreased odds of TBI attribution (odds ratio=0.90, 95% CI=0.83-0.97) and increased odds of PTSD attribution (odds ratio=1.14, 95% CI=1.03-1.26). A PTSD diagnosis was highly associated with PTSD attribution (odds ratio=2.44, 95% CI=1.07-5.58).

CONCLUSIONS

The nature and severity of posttraumatic symptoms appear to play a role in patient beliefs about the causes of symptoms, whether from TBI or PTSD.

Smartphone Application for Measuring Community Participation in Veterans With Traumatic Brain Injury

The goal in the rehabilitation of veterans with mild traumatic brain injury (mTBI) is to improve community participation. A tool that can objectively measure community participation is lacking. The aims of this study are to evaluate the feasibility of a smartphone application (app) called MOVES to objectively measure community participation; and compare MOVES with a self-report questionnaire, and differences between veterans with mTBI and civilians without TBI. It is a 6-week parallel observational study, which included seven veterans with blast-related mTBI and five civilians without TBI. The measures include MOVES, Participation Assessment with Recombined Tools-Objective (self-report participation measure), Satisfaction Questionnaire, and Perceived Accuracy Daily Logs. Participants were mostly satisfied using the MOVES app with 75% retention rate. Perceived accuracy of the MOVES app was 90%, while the two groups showed similar discrepancies between the PART-O and the MOVES (52% vs. 53%). The MOVES app is a feasible option to objectively measure community participation. Self-report was discrepant from the MOVES app for both groups.

Post-concussive symptom endorsement and symptom attribution following remote mild traumatic brain injury in combat-exposed Veterans: An exploratory study

The purpose of this study was to examine rates of and relationships between "post-concussive" symptom endorsement and symptom attribution in Veterans with a history of mild traumatic brain injury (mTBI). This cross-sectional, exploratory study included 48 combat-exposed Iraq/Afghanistan Veterans with remote history of mTBI. All Veterans completed clinical interviews and self-report questionnaires assessing sociodemographic factors, injury and combat-related variables, psychiatric distress, self-efficacy, and coping style. To assess symptom endorsement and symptom attribution, a modified version of the Neurobehavioral Symptom Inventory was administered. Results showed that the most commonly endorsed "post-concussive" symptoms were several non-specific symptoms, while the symptoms most frequently attributed to mTBI included forgetfulness, poor concentration, and headaches. Furthermore, although there were some overlapping correlates of both symptom endorsement and symptom attribution, unique variables were associated with each domain. Specifically, symptom endorsement was uniquely associated with measures of psychiatric distress, while symptom attribution was uniquely associated with having a history of loss of consciousness and a greater degree of combat exposure. Taken together, results suggest that endorsement of symptoms may be significantly impacted by the presence of mental health comorbidities, but that perceptions or beliefs as to why symptoms are occurring are related more to mTBI and combat-related characteristics. Findings offer potential avenues for therapeutic intervention, emphasize the importance of psychoeducation, and highlight the need to consider using alternate terminology for these symptoms that promotes recovery and minimizes misattribution of symptoms.

Psychological predictors of functional outcomes in service members with traumatic brain injury

PRIMARY OBJECTIVE

Research is increasingly demonstrating the significant impact that non-medical factors can have on outcomes of service members (SMs) with mild traumatic brain injury (mTBI). Thus, the current study examined which demographic, TBI-related factors, and psychological variables are most predictive of functional outcomes.

RESEARCH DESIGN

Retrospective database analysis from medical chart review.

METHODS AND PROCEDURES

One hundred forty-one patients who received rehabilitation services at an outpatient TBI military treatment facility between 2013 and 2018. Data collected included demographic variables, time since injury, neuropsychological measures, psychological diagnoses, Personality Assessment Inventory (PAI) scores, and Walter Reed Functional Impairment Scale (FIS). Hierarchical linear regression models were used to predict functional outcomes (measured by FIS total, work, social functioning scales).

MAIN OUTCOMES AND RESULTS

Results indicated that comorbid PTSD diagnosis and PAI Negative Impression Management (NIM) score were predictive of total functional, work, and social outcomes, over and above demographic and TBI-related factors.

CONCLUSIONS

Current findings confirmed the importance of evaluating and treating psychological factors, as well as exploring one's responding style (NIM), when managing chronic mTBI in SMs. Given ongoing findings of psychological underpinnings to mTBI outcome, there is further need to focus on early interventions to optimize psychological and functional outcomes for SMs.

Dissociation of BDNF Val66Met polymorphism on neurocognitive functioning in military veterans with and without a history of remote mild traumatic brain injury

OBJECTIVE

Since neurocognitive functioning following mild traumatic brain injury (mTBI) may be influenced by genetic factors that mediate synaptic survival and repair, we examined the influence of a common brain-derived neurotrophic factor (BDNF) polymorphism (Val66Met) on cognition using a well-defined sample of military Veterans with and without a history of mTBI.

METHOD

Participants included 138 Veterans (mTBI = 75; military controls [MCs] = 63) who underwent neuropsychological testing, including completion of self-report measures assessing psychiatric distress, and BDNF genotyping. The mTBI group was tested roughly 66.7 months following their most recent mTBI. Veterans were divided into two groups-Met+ (Met/Met and Met/Val; n = 49) and Met- (Val/Val; n = 89) and compared on domain-specific cognitive composite scores representing memory, executive functioning, and visuospatial speed.

RESULTS

ANCOVAs adjusting for psychiatric distress, sex, years of education, and ethnicity/race revealed a significant group (mTBI vs. MC) by BDNF genotype (Met + vs. Met-) interaction for the memory (p = .024; η_p ² = .039) and executive functioning (p = .010; η_p ² = .050) composites, such that Met+ mTBI Veterans demonstrated better performance than Met- mTBI Veterans on the cognitive measures, whereas Met+ MCs demonstrated worse performance relative to Met- MCs on the cognitive measures. No significant interaction was observed for the visuospatial speed composite (p = .938; η_p ² < .001).

CONCLUSIONS

These findings offer preliminary evidence to suggest that the Met allele may be protective in the context of remote mTBI. Findings need to be replicated using larger samples, and future studies are necessary to elucidate the precise mechanisms and neural underpinnings of this interaction.

Differences in Posttraumatic Stress Disorder, Depression, and Attribution of Symptoms in Service Members With Combat Versus Noncombat Mild Traumatic Brain Injury

OBJECTIVE

This study compares combat-related mild traumatic brain injury (mTBI) to non-combat-related mTBI in rates of posttraumatic stress disorder (PTSD) and depression after injury, severity of postconcussive symptoms (PCSs), and attribution of those symptoms to mTBI versus PTSD.

PARTICIPANTS

A total of 371 active duty service members (SMs) with documented history of mTBI, divided into combat and non-combat-related cohorts.

DESIGN

Retrospective cohort study.

MAIN MEASURES

Diagnoses of PTSD and depression based on medical record review and self-report. PCSs measured using Neurobehavioral Symptom Index. Attribution of symptoms based on a rating scale asking how much mTBI, PTSD, depression, deployment, or readjustment stress contributed to current symptoms.

RESULTS

Prevalence of PTSD was significantly higher after a combat-related mTBI, compared with a noncombat mTBI (P = .001). Prevalence of depression did not differ between the 2 groups. PCSs were high in both combat and noncombat mTBIs, with no statistical difference between groups. SMs with PTSD reported higher PCS, regardless of combat status. SMs without PTSD attributed symptoms mainly to mTBI, whereas SMs with PTSD, regardless of combat status, were much more likely to attribute symptoms to PTSD, depression, and deployment/readjustment stress.

CONCLUSIONS

This research contributes to our understanding of the complex interplay between mTBI and PTSD in both combat and noncombat injuries within the military population and the importance of addressing both simultaneously.

Injury Severity and Depressive Symptoms in a Post-acute Brain Injury Rehabilitation Sample

This study explored the relationship between injury severity and depressive symptoms for treatment-seeking individuals with traumatic brain injury (TBI). The Mayo Classification System was used to classify TBI severity in 72 participants who completed the Patient Health Questionnaire at admission and at dismissal from rehabilitation. Patients with mild TBI reported more depressive symptoms than those with moderate or severe TBI at admission and at dismissal. Although injury severity groups differed by gender composition, gender had no effect on severity of depressive symptoms. All participants reported fewer depressive symptoms at dismissal from rehabilitation, including lower endorsement of dysphoria by discharge. Participants with mild TBI, however, continued to report depressive symptoms of a mild severity at dismissal, with residual problems with anhedonia. These findings underscore the benefit of interdisciplinary post-acute rehabilitation services for persons with TBI of any severity, including those with mild injury.

White Matter Associations With Performance Validity Testing in Veterans With Mild Traumatic Brain Injury: The Utility of Biomarkers in Complicated Assessment

OBJECTIVE

Failure on performance validity tests (PVTs) is common in Veterans with histories of mild traumatic brain injury (mTBI), leading to questionable validity of clinical presentations.

PARTICIPANTS

Using diffusion tensor imaging, we investigated white matter (WM) integrity and cognition in 79 Veterans with history of mTBI who passed PVTs (n = 43; traumatic brain injury [TBI]-passed), history of mTBI who failed at least 1 PVT (n = 13; TBI-failed), and military controls (n = 23; MCs) with no history of TBI.

RESULTS

The TBI-failed group demonstrated significantly lower cognitive scores relative to MCs and the TBI-passed group; however, no such differences were observed between MCs and the TBI-passed group. On a global measure of WM integrity (ie, WM burden), the TBI-failed group showed more overall WM abnormalities than the other groups. However, no differences were observed between the MCs and TBI-passed group on WM burden. Interestingly, regional WM analyses revealed abnormalities in the anterior internal capsule and cingulum of both TBI subgroups relative to MCs. Moreover, compared with the TBI-passed group, the TBI-failed group demonstrated significantly decreased WM integrity in the corpus callosum.

CONCLUSIONS

Findings revealed that, within our sample, WM abnormalities are evident in those who fail PVTs. This study adds to the burgeoning PVT literature by suggesting that poor PVT performance does not negate the possibility of underlying WM abnormalities in military personnel with history of mTBI.

Staying in service with posttraumatic headache

Objective:

To predict the probability of a military outcome (medical discharge/retirement) in patients with mild traumatic brain injury from a clinical analysis of predetermined patient and headache characteristics.

Methods:

This retrospective cohort study sampled all new patients referred for headache evaluation at the Brain Injury Clinic of the Womack Army Medical Center, Ft. Bragg, NC (August 2008–January 2010). Headache characteristics were extracted and analyzed. Multivariable binary logistic regressions were conducted to predict probability of medical discharge/retirement.

Results:

Ninety-five soldiers (age 31.3 ± 7.4 years, male 93.7%) reported 166 headaches. The most common injury cited was a blast (53.7%). Patients with a continuous headache have almost 4 times the odds of a medically related discharge/retirement compared to patients without such a headache (continuous headache regression coefficient estimate: p < 0.042, odds ratio 3.98, 95% Wald confidence interval 1.05–15.07). Results suggest that, compared to service members who did not have a continuous headache, patients with headache histories with severe holocephalic pain who medicate to keep functioning had the highest probability of medical discharge/retirement.

Conclusions:

Certain headache characteristics may be predictive of military outcomes after mild traumatic brain injury, and we propose a profile that may be useful in that prediction. These data could be useful in future attempts to assess and treat patients with posttraumatic headache and to advise longer-term planning for return to duty or discharge.

Development of a Prediction Model for Post-Concussive Symptoms following Mild Traumatic Brain Injury: A TRACK-TBI Pilot Study

Post-concussive symptoms occur frequently after mild traumatic brain injury (mTBI) and may be categorized as cognitive, somatic, or emotional. We aimed to: 1) assess whether patient demographics and clinical variables predict development of each of these three symptom categories, and 2) develop a prediction model for 6-month post-concussive symptoms. Patients with mTBI (Glasgow Coma Scale score 13-15) from the prospective multi-center Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) Pilot study (2010-2012) who completed the Rivermead Post Concussion Symptoms Questionnaire (RPQ) at 6 months post-injury were included. Linear regression was utilized to determine the predictive value of candidate predictors for cognitive, somatic, and emotional subscales individually, as well as the overall RPQ. The final prediction model was developed using least absolute shrinkage and selection operator shrinkage and bootstrap validation. We included 277 mTBI patients (70% male; median age 42 years). No major differences in the predictive value of our set of predictors existed for the cognitive, somatic, and emotional subscales, and therefore one prediction model for the RPQ total scale was developed. Years of education, pre-injury psychiatric disorders, and prior TBI were the strongest predictors of 6-month post-concussive symptoms. The total set of predictors explained 21% of the variance, which decreased to 14% after bootstrap validation. Demographic and clinical variables at baseline are predictive of 6-month post-concussive symptoms following mTBI; however, these variables explain less than one-fifth of the total variance in outcome. Model refinement with larger datasets, more granular variables, and objective biomarkers are needed before implementation in clinical practice.

Elevated rates of memory impairment in military service-members and veterans with posttraumatic stress disorder

INTRODUCTION

Studies investigating the neurocognitive effects of posttraumatic stress disorder (PTSD) routinely find "deficits" in various cognitive domains. However, the rate of cognitive impairment in individuals with PTSD remains unclear, as studies have focused on null hypothesis testing (NHT) and inferring patterns of impairment rather than empirically determining the rate of cognitive impairment in this sample.

METHOD

This study examined rates of cognitive impairment using a domain-specific approach in non-treatment-seeking Operation Enduring Freedom/Operation Iraqi Freedom/Operation New Dawn service members and veterans with (n = 92) and without (n = 79) PTSD and without substance abuse/dependence who passed a performance validity measure and were matched on age, education, estimated IQ, and ethnicity. Chi-square analyses were used to compare the rate of cognitive impairment across groups based on normative scores using three cutoffs (-1, -1.5, and -2 SDs). NHT was also used to compare performances across groups.

RESULTS

Individuals with PTSD showed higher rates of impairment in memory (-1-SD cutoff) than controls, but equivalent rates of impairment in attention, processing speed, and executive functioning; no significant differences were found on NHT. Impairment in any domain was also more prevalent in PTSD (-1-, -1.5-, and -2-SD cutoffs). No differences were found on NHT or rates of impairment in individuals with PTSD with (n = 34) and without (n = 58) depression.

CONCLUSIONS

Patients with PTSD were more likely to meet criteria for memory impairment and to show impairment in any domain than controls. Patients with PTSD and comorbid depression were no more likely to be impaired in any cognitive domain or to have lower scores on individual cognitive tasks than patients with PTSD alone. Clinicians noting cognitive impairment in individuals with PTSD should exercise caution before ascribing that impairment to another etiology if deficits are limited to memory.

Cross-Phenotype Polygenic Risk Score Analysis of Persistent Post-Concussive Symptoms in U.S. Army Soldiers with Deployment-Acquired Traumatic Brain Injury

Traumatic brain injury (TBI) contributes to the increased rates of suicide and post-traumatic stress disorder in military personnel and veterans, and it is also associated with the risk for neurodegenerative and psychiatric disorders. A cross-phenotype high-resolution polygenic risk score (PRS) analysis of persistent post-concussive symptoms (PCS) was conducted in 845 U.S. Army soldiers who sustained TBI during their deployment. We used a prospective longitudinal survey of three brigade combat teams to assess deployment-acquired TBI and persistent physical, cognitive, and emotional PCS. PRS was derived from summary statistics of large genome-wide association studies of Alzheimer's disease, Parkinson's disease, schizophrenia, bipolar disorder, and major depressive disorder (MDD); and for years of schooling, college completion, childhood intelligence, infant head circumference (IHC), and adult intracranial volume. Although our study had more than 95% of statistical power to detect moderate-to-large effect sizes, no association was observed with neurodegenerative and psychiatric disorders, suggesting that persistent PCS does not share genetic components with these traits to a moderate-to-large degree. We observed a significant finding: subjects with high IHC PRS recovered better from cognitive/emotional persistent PCS than the other individuals (R² = 1.11%; p = 3.37 × 10^-3). Enrichment analysis identified two significant Gene Ontology (GO) terms related to this result: GO:0050839∼Cell adhesion molecule binding (p = 8.9 × 10^-6) and GO:0050905∼Neuromuscular process (p = 9.8 × 10^-5). In summary, our study indicated that the genetic predisposition to persistent PCS after TBI does not have substantial overlap with neurodegenerative and psychiatric diseases, but mechanisms related to early brain growth may be involved.

Auditory difficulties in blast-exposed Veterans with clinically normal hearing

Vast numbers of blast-injured Operation Iraqi Freedom/Operation Enduring Freedom/Operation New Dawn personnel report postconcussive symptoms that include headache, dizziness, poor memory, and difficulty concentrating. In addition, many report hearing problems, such as difficulty understanding speech in noise, yet have no measureable peripheral auditory deficits. In this article, self-report and performance-based measures were used to assess 99 blast-exposed Veterans. All participants reported auditory problems in difficult listening situations but had clinically normal hearing. Participants' scores on self-report questionnaires of auditory difficulties were more similar to scores of older individuals with hearing impairment than to those of younger individuals with normal hearing. Participants showed deficits relative to published normative data on a number of performance-based tests that have demonstrated sensitivity to auditory processing deficits. There were several measures on which more than the expected number of participants (15.9%) performed one or more standard deviations below the mean. These were assessments of speech understanding in noise, binaural processing, temporal resolution, and speech segregation. Performance was not universally poor, with approximately 53% of participants performing abnormally on between 3 and 6 of the 10 measures. We concluded that participants exhibited task-specific deficits that add to the evidence suggesting that blast injury results in damage to the central auditory system.

CLINICAL TRIALS REGISTRATION

ClinicalTrials.gov; Approaches to Auditory Rehabilitation for Mild Traumatic Brain Injury (mTBI); NCT00930774; https://clinicaltrials.gov/ct2/show/NCT00930774?term=NCT00930774&rank=1.

Apolipoprotein E (APOE) ϵ4 Allele Is Associated with Increased Symptom Reporting Following Sports Concussion

Exploring the relationship between genetic factors and outcome following brain injury has received increased attention in recent years. However, few studies have evaluated the influence of genes on specific sequelae of concussion. The purpose of this study was to determine how the ϵ4 allele of the apolipoprotein E (APOE) gene influences symptom expression following sports-related concussion. Participants included 42 collegiate athletes who underwent neuropsychological testing, including completion of the Post-Concussion Symptom Scale (PCSS), within 3 months after sustaining a concussion (73.8% were evaluated within 1 week). Athletes provided buccal samples that were analyzed to determine the make-up of their APOE genotype. Dependent variables included a total symptom score and four symptom clusters derived from the PCSS. Mann-Whitney U tests showed higher scores reported by athletes with the ϵ4 allele compared to those without it on the total symptom score and the physical and cognitive symptom clusters. Furthermore, logistic regression showed that the ϵ4 allele independently predicted those athletes who reported physical and cognitive symptoms following concussion. These findings illustrate that ϵ4+ athletes report greater symptomatology post-concussion than ϵ4- athletes, suggesting that the ϵ4 genotype may confer risk for poorer post-concussion outcome. (JINS, 2016, 22, 89-94).

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.

Resilience and symptom reporting following mild traumatic brain injury in military service members

PRIMARY OBJECTIVE

The purpose of this study was to examine the relationship between resilience and symptom reporting following mild traumatic brain injury (mTBI). It was hypothesized that, as resilience increases, self-reported symptoms would decrease.

RESEARCH DESIGN

Cross-sectional design.

METHODS AND PROCEDURES

Participants were 142 US military service members who sustained a mTBI, divided into three resilience groups based on participants' responses on the Response to Stressful Experiences Scale: Moderate (n = 42); High (n = 51); and Very High (n = 49). Participants completed the Neurobehavioral Symptom Inventory (NSI) and PTSD Checklist-Civilian Version (PCL-C) within 12 months following injury.

MAIN OUTCOMES AND RESULTS

There were significant main effects for the NSI total score, cognitive cluster and affective cluster, as well as for the PCL-C total score, avoidance cluster and hyperarousal cluster. Pairwise comparisons revealed that there was a negative relationship between resilience and self-reported symptoms overall. Specifically, participants with higher resilience reported fewer post-concussion and PTSD-related symptoms than participants with lower levels of resilience.

CONCLUSIONS

These findings underscore the important role that resilience plays in symptom expression in military service members with mTBI and suggest that research on targeted interventions to increase resilience in the acute phase following injury is indicated.

Racial/Ethnic Differences in Combat- and Non-Combat-Associated Traumatic Brain Injury Severity in the Veterans Health Administration: 2004-2010

OBJECTIVES

We examined the association between traumatic brain injury (TBI) severity and combat exposure by race/ethnicity.

METHODS

We estimated logit models of the fully adjusted association of combat exposure with TBI severity in separate race/ethnicity models for a national cohort of 132 995 veterans with TBI between 2004 and 2010.

RESULTS

Of veterans with TBI, 25.8% had served in a combat zone. Mild TBI increased from 11.5% to 40.3%, whereas moderate or severe TBI decreased from 88.5% to 59.7%. Moderate or severe TBI was higher in non-Hispanic Blacks (80.0%) and Hispanics (89.4%) than in non-Hispanic Whites (71.9%). In the fully adjusted all-race/ethnicity model, non-Hispanic Blacks (1.44; 95% confidence interval [CI] = 1.37, 1.52) and Hispanics (1.47; 95% CI = 1.26, 1.72) had higher odds of moderate or severe TBI than did non-Hispanic Whites. However, combat exposure was associated with higher odds of mild TBI in non-Hispanic Blacks (2.48; 95% CI = 2.22, 2.76) and Hispanics (3.42; 95% CI = 1.84, 6.35) than in non-Hispanic Whites (2.17; 95% CI = 2.09, 2.26).

CONCLUSIONS

Research is needed to understand racial differences in the effect of combat exposure on mild TBI and on interventions to prevent TBI across severity levels.

Diffusion tensor imaging findings and postconcussion symptom reporting six weeks following mild traumatic brain injury

The purpose of this study is to examine the relation between the microstructural architecture of white matter, as measured by diffusion tensor imaging (DTI), and postconcussion symptom reporting 6-8 weeks following mild traumatic brain injury (MTBI). Participants were 108 patients prospectively recruited from a Level 1 Trauma Center (Vancouver, BC, Canada) following an orthopedic injury [i.e., 36 trauma controls (TCs)] or MTBI (n = 72). DTI of the whole brain was undertaken using a Phillips 3T scanner at 6-8 weeks postinjury. Participants also completed a 5 h neurocognitive test battery and a brief battery of self-report measures (e.g., depression, anxiety, and postconcussion symptoms). The MTBI sample was divided into two groups based on ICD-10 criteria for postconcussional syndrome (PCS): first, PCS-present (n = 20) and second, PCS-absent (n = 52). There were no significant differences across the three groups (i.e., TC, PCS-present, and PCS-absent) for any of the neurocognitive measures (p = .138-.810). For the self-report measures, the PCS-present group reported significantly more anxiety and depression symptoms compared with the PCS-absent and TC groups (p < .001, d = 1.63-1.89, very large effect sizes). For the DTI measures, there were no significant differences in fractional anisotropy, axial diffusivity, radial diffusivity, or mean diffusivity when comparing the PCS-present and PCS-absent groups. However, there were significant differences (p < .05) in MD and RD when comparing the PCS-present and TC groups. There were significant differences in white matter between TC subjects and the PCS-present MTBI group, but not the PCS-absent MTBI group. Within the MTBI group, white-matter changes were not a significant predictor of ICD-10 PCS.

Greater physiological and behavioral effects of interrupted stress pattern compared to daily restraint stress in rats

Repeated stress can trigger a range of psychiatric disorders, including anxiety. The propensity to develop abnormal behaviors after repeated stress is related to the severity, frequency and number of stressors. However, the pattern of stress exposure may contribute to the impact of stress. In addition, the anxiogenic nature of repeated stress exposure can be moderated by the degree of coping that occurs, and can be reflected in homotypic habituation to the repeated stress. However, expectations are not clear when a pattern of stress presentation is utilized that diminishes habituation. The purpose of these experiments is to test whether interrupted stress exposure decreases homotypic habituation and leads to greater effects on anxiety-like behavior in adult male rats. We found that repeated interrupted restraint stress resulted in less overall homotypic habituation compared to repeated daily restraint stress. This was demonstrated by greater production of fecal boli and greater corticosterone response to restraint. Furthermore, interrupted restraint stress resulted in a lower body weight and greater adrenal gland weight than daily restraint stress, and greater anxiety-like behavior in the elevated plus maze. Control experiments demonstrated that these effects of the interrupted pattern could not be explained by differences in the total number of stress exposures, differences in the total number of days that the stress periods encompased, nor could it be explained as a result of only the stress exposures after an interruption from stress. These experiments demonstrate that the pattern of stress exposure is a significant determinant of the effects of repeated stress, and that interrupted stress exposure that decreases habituation can have larger effects than a greater number of daily stress exposures. Differences in the pattern of stress exposure are therefore an important factor to consider when predicting the severity of the effects of repeated stress on psychiatric disorders.

Factors influencing postconcussion and posttraumatic stress symptom reporting following military-related concurrent polytrauma and traumatic brain injury

The purpose of this study was to identify factors that are predictive of, or associated with, high endorsement of postconcussion and posttraumatic stress symptoms following military-related traumatic brain injury (TBI). Participants were 1,600 U.S. service members (age: M = 27.1, SD = 7.1; 95.4% male) who had sustained a mild-to-moderate TBI and who had been evaluated by the Defense and Veterans Brain Injury Center at one of six military medical centers. Twenty-two factors were examined that included demographic, injury circumstances/severity, treatment/evaluation, and psychological/physical variables. Four factors were statistically and meaningfully associated with clinically elevated postconcussion symptoms: (i) low bodily injury severity, (ii) posttraumatic stress, (iii) depression, and (iv) military operation where wounded (p < .001, 43.2% variance). The combination of depression and posttraumatic stress symptoms accounted for the vast majority of unique variance (41.5%) and were strongly associated with, and predictive of, clinically elevated postconcussion symptoms [range: odds ratios (OR) = 4.24-7.75; relative risk (RR) = 2.28-2.51]. Five factors were statistically and meaningfully associated with clinically elevated posttraumatic stress symptoms: (i) low bodily injury severity, (ii) depression, (iii) a longer time from injury to evaluation, (iv) military operation where wounded, and (v) current auditory deficits (p < .001; 65.6% variance accounted for). Depression alone accounted for the vast majority of unique variance (60.0%) and was strongly associated with, and predictive of, clinically elevated posttraumatic stress symptoms (OR = 38.78; RR = 4.63). There was a very clear, strong, and clinically meaningful association between depression, posttraumatic stress, and postconcussion symptoms in this sample. Brain injury severity, however, was not associated with symptom reporting following TBI.

A comparison of insufficient effort rates, neuropsychological functioning, and neuropsychiatric symptom reporting in military veterans and civilians with chronic traumatic brain injury

Neuropsychological evaluation of persons with chronic traumatic brain injury (TBI) symptoms is complicated by multiple factors. The authors explored the impact of mechanism of injury, effort testing performance, and neuropsychiatric status in a sample of military veterans (V-TBI) and civilians (C-TBI) with chronic TBI. V-TBI (n = 74), C-TBI (n = 67), and healthy civilian control (C-HC) participants (n = 66), completed a battery of neuropsychological, effort, and self-report neuropsychiatric measures. Results indicated that C-HC and C-TBI participants exhibited comparably low failure rates on effort tests (6% and 3%, respectively). V-TBI participants exhibited significantly higher rates of failure (18%). Subgroups (n = 20) of effort-screened participants matched for demographics and disability level were compared regarding neuropsychological performance and neuropsychiatric self-report. Both TBI groups exhibited limited neuropsychological impairment, relative to the C-HC participants. The V-TBI group exhibited pronounced neuropsychiatric symptomology compared with the other participant groups. The implications of these findings are discussed for evaluation in the context of disability and litigation.

Mental Health is Central to Good Neurorehabilitation after TBI

Those after traumatic brain injury (TBI) who suffer mental health problems, by which I mean problems that a psychiatrist might understand as falling within their remit, suffer a double whammy. Not only do they suffer the stigma of the disabled, but even within this group they may be stigmatised. It has often been my experience that while families will allow for their injured loved one to be under the care of rehabilitation services, including a psychologist, they baulk at the possibility that their loved one may need psychiatric care. This comes to a head when it comes to detaining a patient, in England and Wales, under the Mental Health Act; this may be vigorously resisted by family because of what they infer this says about their loved one's sanity.