Early Brain Amyloid Accumulation at PET in Military Instructors Exposed to Subconcussive Blast Injuries.

Background Traumatic brain injury (TBI) is the leading cause of disability in young adults. Recurrent TBI is associated with a range of neurologic sequelae, but the contributing factors behind the development of such chronic encephalopathy are poorly understood. Purpose To quantify early amyloid ß deposition in the brain of otherwise healthy adult men exposed to repeated subconcussive blast injury using amyloid PET. Materials and Methods In this prospective study from January 2020 to December 2021, military instructors who were routinely exposed to repeated blast events were evaluated at two different points: baseline (before blast exposure from breacher or grenade) and approximately 5 months after baseline (after blast exposure). Age-matched healthy control participants not exposed to blasts and without a history of brain injury were evaluated at similar two points. Neurocognitive evaluation was performed with standard neuropsychologic testing in both groups. Analysis of PET data consisted of standardized uptake value measurements in six relevant brain regions and a whole-brain voxel-based statistical approach. Results Participants were men (nine control participants [median age, 33 years; IQR, 32-36 years] and nine blast-exposed participants [median age, 33 years; IQR, 30-34 years]; P = .82). In the blast-exposed participants, four brain regions showed significantly increased amyloid deposition after blast exposure: inferomedial frontal lobe (P = .004), precuneus (P = .02), anterior cingulum (P = .002), and superior parietal lobule (P = .003). No amyloid deposition was observed in the control participants. Discriminant analysis on the basis of regional changes of amyloid accumulation correctly classified the nine healthy control participants as healthy control participants (100%), and seven of the nine blast-exposed participants (78%) were correctly classified as blast exposed. Based on the voxel-based analysis, whole-brain parametric maps of early abnormal early amyloid uptake were obtained. Conclusion Early brain amyloid accumulation was identified and quantified at PET in otherwise healthy adult men exposed to repetitive subconcussive traumatic events. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Haller in this issue.

Close proximity to blast: No long-term or lasting effect on cognitive performance in service members with and without TBI during blast exposure.

OBJECTIVE: Blast related characteristics may contribute to the diversity of findings on whether mild traumatic brain injury sustained during war zone deployment has lasting cognitive effects. This study aims to evaluate whether a history of blast exposure at close proximity, defined as exposure within 30 feet, has long-term or lasting influences on cognitive outcomes among current and former military personnel. METHOD: One hundred participants were assigned to one of three groups based on a self-report history of blast exposure during combat deployments: 47 close blast, 14 non-close blast, and 39 comparison participants without blast exposure. Working memory, processing speed, verbal learning/memory, and cognitive flexibility were evaluated using standard neuropsychological tests. In addition, assessment of combat exposure and current post-concussive, posttraumatic stress, and depressive symptoms, and headache was performed via self-report measures. Variables that differed between groups were controlled as covariates. RESULTS: No group differences survived Bonferroni correction for family-wise error rate; the close blast group did not differ from non-close blast and comparison groups on measures of working memory, processing speed, verbal learning/memory, or cognitive flexibility. Controlling for covariates did not alter these results. CONCLUSION: No evidence emerged to suggest that a history of close blast exposure was associated with decreased cognitive performance when comparisons were made with the other groups. Limited characterization of blast contexts experienced, self-report of blast distance, and heterogeneity of injury severity within the groups are the main limitations of this study.

Remote blast-related mild traumatic brain injury is associated with differential expression of exosomal microRNAs identified in neurodegenerative and immunological processes.

BACKGROUND: Blast traumatic brain injury (TBI) and subconcussive blast exposure have been associated, pathologically, with chronic traumatic encephalopathy (CTE) and, clinically, with cognitive and affective symptoms, but the underlying pathomechanisms of these associations are not well understood. We hypothesized that exosomal microRNA (miRNA) expression, and their relation to neurobehavioral outcomes among Veterans with blunt or blast mild TBI (mTBI) may provide insight into possible mechanisms for these associations and therapeutic targets. METHODS: This is a subanalysis of a larger Chronic Effects of Neurotrauma Consortium Biomarker Discovery Project. Participants (n = 152) were divided into three groups: Controls (n = 35); Blunt mTBI only (n = 54); and Blast/blast+blunt mTBI (n = 63). Postconcussive and post-traumatic stress symptoms were evaluated using the NSI and PCL-5, respectively. Exosomal levels of 798 miRNA expression were measured. RESULTS: In the blast mTBI group, 23 differentially regulated miRNAs were observed compared to the blunt mTBI group and 23 compared to controls. From the pathway analysis, significantly dysregulated miRNAs in the blast exposure group correlated with inflammatory, neurodegenerative, and androgen receptor pathways. DISCUSSION: Our findings suggest that chronic neurobehavioral symptoms after blast TBI may pathomechanistically relate to dysregulated cellular pathways involved with neurodegeneration, inflammation, and central hormonal regulation.

Neuropsychiatric Outcomes in UK Military Veterans With Mild Traumatic Brain Injury and Vestibular Dysfunction.

OBJECTIVE: To estimate the frequency of vestibular dysfunction following blunt, blast, and combined blunt and blast mild traumatic brain injury (mTBI) and thereon assess the long-term impact of vestibular dysfunction on neurobehavioral function and disability independently of comorbid psychiatric symptoms. SETTING: Combat Stress residential and Veterans' Outreach drop-in centers for psychological support. PARTICIPANTS: One hundred sixty-two help-seeking UK military veterans. MAIN MEASURES: Self-reported frequency and severity of mTBI (using the Ohio State TBI Identification Method), Vertigo Symptom Scale, PTSD Checklist for DSM-5, Kessler Psychological Distress Scale (K10), Neurobehavioral Symptom Inventory, Headache Impact Test (HIT6), Memory Complaints Inventory, World Health Organization Disability Assessment Schedule II short version (WHODAS 2.0). RESULTS: Seventy-two percent of the sample reported 1 or more mTBIs over their lifetime. Chi-square analyses indicated that vestibular disturbance, which affected 69% of participants, was equally prevalent following blunt (59%) or blast (47%) injury and most prevalent following blunt and blast combined (83%). Mediation analysis indicated that when posttraumatic stress disorder, depression, and anxiety were taken into account, vestibular dysfunction in participants with mTBI was directly and independently associated with increased postconcussive symptoms and functional disability. CONCLUSION: Vestibular dysfunction is common after combined blunt and blast mTBI and singularly predictive of poor long-term mental health. From a treatment perspective, vestibular rehabilitation may provide relief from postconcussive symptoms other than dizziness and imbalance.

Multimorbidity and quality of life after blast-related injury among US military personnel: a cluster analysis of retrospective data.

BACKGROUND: Blast injury emerged as a primary source of morbidity among US military personnel during the recent conflicts in Iraq and Afghanistan, and led to an array of adverse health outcomes. Multimorbidity, or the presence of two or more medical conditions in an individual, can complicate treatment strategies. To date, there is minimal research on the impact of multimorbidity on long-term patient-reported outcomes. We aimed to define multimorbidity patterns in a population of blast-injured military personnel, and to examine these patterns in relation to long-term quality of life (QOL). METHODS: A total of 1972 US military personnel who sustained a blast-related injury during military operations in Iraq and Afghanistan were identified from clinical records. Electronic health databases were used to identify medical diagnoses within the first year postinjury, and QOL was measured with a web-based assessment. Hierarchical cluster analysis methods using Ward's minimum variance were employed to identify clusters with related medical diagnosis categories. Duncan's multiple range test was used to group clusters into domains by QOL. RESULTS: Five distinct clusters were identified and grouped into three QOL domains. The lowest QOL domain contained one cluster with a clinical triad reflecting musculoskeletal pain, concussion, and mental health morbidity. The middle QOL domain had two clusters, one with concussion/anxiety predominating and the other with polytrauma. The highest QOL domain had two clusters with little multimorbidity aside from musculoskeletal pain. CONCLUSIONS: The present study described blast-related injury profiles with varying QOL levels that may indicate the need for integrated health services. Implications exist for current multidisciplinary care of wounded active duty and veteran service members, and future research should determine whether multimorbidity denotes distinct post-blast injury syndromes.

A prediction model of military combat and training exposures on VA service-connected disability: a CENC study.

Background: Research has shown that number of and blast-related Traumatic Brain Injuries (TBI) are associated with higher levels of service-connected disability (SCD) among US veterans. This study builds and tests a prediction model of SCD based on combat and training exposures experienced during active military service.Methods: Based on 492 US service member and veteran data collected at four Department of Veterans Affairs (VA) sites, traditional and Machine Learning algorithms were used to identify a best set of predictors and model type for predicting %SCD ≥50, the cut-point that allows for veteran access to 0% co-pay for VA health-care services.Results: The final model of predicting %SCD ≥50 in veterans revealed that the best blast/injury exposure-related predictors while deployed or non-deployed were: 1) number of controlled detonations experienced, 2) total number of blast exposures (including controlled and uncontrolled), and 3) the total number of uncontrolled blast and impact exposures.Conclusions and Relevance: We found that the highest blast/injury exposure predictor of %SCD ≥50 was number of controlled detonations, followed by total blasts, controlled or uncontrolled, and occurring in deployment or non-deployment settings. Further research confirming repetitive controlled blast exposure as a mechanism of chronic brain insult should be considered.

Verbal Memory Deficits in OEF/OIF/OND Veterans Exposed to Blasts at Close Range.

OBJECTIVES: This study investigated the relationship between close proximity to detonated blast munitions and cognitive functioning in OEF/OIF/OND Veterans. METHODS: A total of 333 participants completed a comprehensive evaluation that included assessment of neuropsychological functions, psychiatric diagnoses and history of military and non-military brain injury. Participants were assigned to a Close-Range Blast Exposure (CBE) or Non-Close-Range Blast Exposure (nonCBE) group based on whether they had reported being exposed to at least one blast within 10 meters. RESULTS: Groups were compared on principal component scores representing the domains of memory, verbal fluency, and complex attention (empirically derived from a battery of standardized cognitive tests), after adjusting for age, education, PTSD diagnosis, sleep quality, substance abuse disorder, and pain. The CBE group showed poorer performance on the memory component. Rates of clinical impairment were significantly higher in the CBE group on select CVLT-II indices. Exploratory analyses examined the effects of concussion and multiple blasts on test performance and revealed that number of lifetime concussions did not contribute to memory performance. However, accumulating blast exposures at distances greater than 10 meters did contribute to poorer performance. CONCLUSIONS: Close proximity to detonated blast munitions may impact memory, and Veterans exposed to close-range blast are more likely to demonstrate clinically meaningful deficits. These findings were observed after statistically adjusting for comorbid factors. Results suggest that proximity to blast should be considered when assessing for memory deficits in returning Veterans. Comorbid psychiatric factors may not entirely account for cognitive difficulties. (JINS, 2018, 24, 466-475).

Outcomes Associated With Blast Versus Nonblast-Related Traumatic Brain Injury in US Military Service Members and Veterans: A Systematic Review.

OBJECTIVES: To systematically review the literature on comparative clinical and functional outcomes following blast-related versus nonblast-related traumatic brain injury (TBI) among US service members and Veterans. DESIGN: MEDLINE search (January 2001 to June 2016) supplemented with hand search of reference lists and input from peer reviewers. RESULTS: Thirty-one studies (in 33 articles) reported on health outcomes; only 2 were rated low risk of bias. There was variation in outcomes reported and methods of assessment. Blast and nonblast TBI groups had similar rates of depression, sleep disorders, alcohol misuse, vision loss, vestibular dysfunction, and functional status. Comparative outcomes were inconsistent with regard to posttraumatic stress disorder diagnosis or symptoms, headache, hearing loss, and neurocognitive function. Mortality, burn, limb loss, and quality of life were each reported in few studies, most with small sample sizes. Only 4 studies reported outcomes by blast injury mechanism. CONCLUSIONS: Most clinical and functional outcomes appeared comparable in military service members and Veterans with TBI, regardless of blast exposure. Inconsistent findings and limited outcomes reporting indicate that more research is needed to determine whether there is a distinct pattern of impairments and comorbidities associated with blast-related TBI.

Blast-related disinhibition and risk seeking in mice and combat Veterans: Potential role for dysfunctional phasic dopamine release.

Mild traumatic brain injury (mTBI) caused by exposure to high explosives has been called the "signature injury" of the wars in Iraq and Afghanistan. There is a wide array of chronic neurological and behavioral symptoms associated with blast-induced mTBI. However, the underlying mechanisms are not well understood. Here we used a battlefield-relevant mouse model of blast-induced mTBI and in vivo fast-scan cyclic voltammetry (FSCV) to investigate whether the mesolimbic dopamine system contributes to the mechanisms underlying blast-induced behavioral dysfunction. In mice, blast exposure increased novelty seeking, a behavior closely associated with disinhibition and risk for subsequent maladaptive behaviors. In keeping with this, we found that veterans with blast-related mTBI reported greater disinhibition and risk taking on the Frontal Systems Behavior Scale (FrSBe). In addition, in mice we report that blast exposure causes potentiation of evoked phasic dopamine release in the nucleus accumbens. Taken together these findings suggest that blast-induced changes in the dopaminergic system may mediate aspects of the complex array of behavioral dysfunctions reported in blast-exposed veterans.

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.

Preclinical modelling of militarily relevant traumatic brain injuries: Challenges and recommendations for future directions.

As a follow-up to the 2008 state-of-the-art (SOTA) conference on traumatic brain injuries (TBIs), the 2015 event organized by the United States Department of Veterans Affairs (VA) Office of Research and Development (ORD) analysed the knowledge gained over the last 7 years as it relates to basic scientific methods, experimental findings, diagnosis, therapy, and rehabilitation of TBIs and blast-induced neurotraumas (BINTs). The current article summarizes the discussions and recommendations of the scientific panel attending the Preclinical Modeling and Therapeutic Development Workshop of the conference, with special emphasis on factors slowing research progress and recommendations for ways of addressing the most significant pitfalls.

Media Use and Exposure to Graphic Content in the Week Following the Boston Marathon Bombings.

Traditional and new media inform and expose the public to potentially distressing graphic content following disasters, but predictors of media use have received limited attention. We examine media-use patterns after the Boston Marathon bombings (BMB) in a representative national U.S. sample (n = 2888), with representative oversamples from metropolitan Boston (n = 845) and New York City (n = 941). Respondents completed an Internet-based survey 2-4 weeks post-BMB. Use of traditional media was correlated with older age, prior indirect media-based exposure to collective traumas, and direct BMB exposure. New media use was correlated with younger age and prior direct exposure to collective traumas. Increased television and online news viewing were associated with exposure to more graphic content. The relationship between traditional and new media was stronger for young adults than all other age groups. We offer insights about the relationship between prior collective trauma exposures and media use following subsequent disasters and identify media sources likely to expose people to graphic content.

Characterization of acute stress reaction following an IED blast-related mild traumatic brain injury.

PRIMARY OBJECTIVE: To characterize an acute stress reaction (ASR) following an improvised explosive device (IED) blast-related mild traumatic brain injury (mTBI). RESEARCH DESIGN: Participants were male, US military personnel treated in Afghanistan within 4 days following an IED-related mTBI event (n = 239). METHODS AND PROCEDURES: Demographics, diagnosis of ASR, injury history and self-reported mTBIs, blast exposures and psychological health histories were recorded. MAIN OUTCOMES AND RESULTS: In total, 12.5% of patients met ASR criteria. Patients with ASR were significantly younger and junior in rank (p < 0.05). Patients with ASR were more likely to experience the IED-blast while dismounted, report a loss of consciousness (LOC) and higher pain levels (p < 0.05). Adjusting for age and rank, multivariate logistic regression showed an association between mTBI history and ASR (AOR = 1.405; 95% CI = 1.105-1.786, p < 0.01). Adjusting for mechanism of injury (dismounted vs. mounted), LOC and pain, multivariate logistic regression showed an association between mTBI history and ASR (AOR = 1.453; 95% CI = 1.132-1.864, p < 0.01). Prior blast exposure and past psychological health issues were not associated with ASR. CONCLUSIONS: A history of multiple mTBIs is associated with increased risk of ASR. Future research is warranted.

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.

Prevalence of mental health conditions after military blast exposure, their co-occurrence, and their relation to mild traumatic brain injury.

PRIMARY OBJECTIVES: To measure common psychiatric conditions after military deployment with blast exposure and test relationships to post-concussion syndrome (PCS) symptoms and mild traumatic brain injury (mTBI) history. RESEARCH DESIGN: Cross-sectional. METHODS AND PROCEDURES: Service members or Veterans (n = 107) within 2 years of blast exposure underwent structured interviews for mTBI, post-traumatic stress disorder (PTSD) and multiple mood and anxiety diagnoses. MAIN OUTCOMES AND RESULTS: MTBI history and active PTSD were both common, additionally 61% had at least one post-deployment mood or anxiety disorder episode. Psychiatric diagnoses had a high degree of comorbidity. Most dramatically, depression was 43-times (95% CI = 11-165) more likely if an individual had PTSD. PCS symptoms were greater in those with post-deployment PTSD or mood diagnosis. However, neither mTBI nor blast exposure history had an effect on the odds of having PTSD, mood or anxiety condition. CONCLUSIONS: These findings support that psychiatric conditions beyond PTSD are common after military combat deployment with blast exposure. They also highlight the non-specificity of post-concussion type symptoms. While some researchers have implicated mTBI history as a contributor to post-deployment mental health conditions, no clear association was found. This may partly be due to the more rigorous method of retrospective mTBI diagnosis determination.

Chapter 3 animal models of traumatic brain injury: is there an optimal model that parallels human brain injury?

Traumatic brain injury (TBI) is the leading cause of mortality and morbidity in the younger population worldwide. Survivors of TBI often experience long-term disability in the form of cognitive, sensorimotor, and affective impairments. Despite the high prevalence in, and cost of TBI to, both individuals and society, some of its underlying pathophysiology is not completely understood. Animal models have been developed over the past few decades to closely replicate the different facets of TBI in humans to better understand the underlying pathophysiology and behavioral impairments and assess potential therapies that can promote neuroprotection. However, no effective treatment for TBI has been established to date in the clinical setting, despite promising results generated in preclinical studies in the use of neuroprotective strategies. The failure to translate results from preclinical studies to the clinical setting underscores a compelling need to revisit the current state of knowledge in the use of animal models in TBI.

Moderate-to-severe traumatic brain injury.

Managing patients with moderate-to-severe traumatic brain injury (TBI), particularly those with combat-related blast injury, is exceptionally challenging. Optimal care requires the coordinated efforts of numerous providers, contributing to an interdisciplinary team. Given the complexities of TBI and the variety of physiologic, physical, cognitive, behavioral, and emotional manifestations of the injury, a holistic approach to patient care is needed throughout the entire continuum of care. In this article, the authors provide an overview of how interdisciplinary care is provided from the acute to the chronic settings, and illustrate the important role that rehabilitation plays throughout the continuum of care in facilitating maximizing recovery, functional independence, and quality of life. Common conditions associated with TBI are illustrated through a case presentation of an individual with blast-related polytrauma and help to frame a more detailed discussion of subtopics including neurointensive care, posttraumatic seizures, venous thromboembolic disease prevention, spasticity management, vestibular disorders, endocrine dysfunction, and psychological trauma.

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.

Head and facial injuries due to cluster munitions.

Cluster munitions are weapons that scatter smaller sub-munitions intended to kill or mutilate on impact. They have been used by the Israeli army in the south of Lebanon and are now scattered over wide rural areas affecting its inhabitants. Because of their easily "pickable" nature, sub-munitions can inflict injuries to the head and face regions. In this study, we aimed to explore the head and face injuries along with their clinical features in a group of Lebanese patients who suffered from such injuries due to a sub-munition's detonation. The study included all the cases reported between 14 August 2006 and 15 February 2013, with head and face injuries related to cluster bombs. Injuries were classified into brain, eye, otologic and auditory impairments, oral and maxillofacial, and skin and soft-tissue injuries. Psychological effects of these patients were also examined as for post-traumatic stress disorder, major depressive disorder, generalized anxiety disorder and acute stress syndrome. During the study period, there were 417 casualties as a result of cluster munitions' blasts. Out of the total number of victims, 29 (7 %) were injured in the head and the face region. The convention on cluster munitions of 2008 should be adhered to, as these inhumane weapons indiscriminately and disproportionately harm innocent civilians, thereby violating the well-established international principles governing conflict and war today.

The Boston Assessment of Traumatic Brain Injury-Lifetime (BAT-L) semistructured interview: evidence of research utility and validity.

OBJECTIVE: Report the prevalence of lifetime and military-related traumatic brain injuries (TBIs) in Operation Enduring Freedom and Operation Iraqi Freedom (OEF/OIF) veterans and validate the Boston Assessment of TBI-Lifetime (BAT-L). SETTING: The BAT-L is the first validated, postcombat, semistructured clinical interview to characterize head injuries and diagnose TBIs throughout the life span. PARTICIPANTS: Community-dwelling convenience sample of 131 OEF/OIF veterans. DESIGN: TBI criteria (alteration of mental status, posttraumatic amnesia, and loss of consciousness) were evaluated for all possible TBIs, including a novel evaluation of blast exposure. MAIN MEASURES: BAT-L, Ohio State University TBI Identification Method (OSU-TBI-ID). RESULTS: About 67% of veterans incurred a TBI in their lifetime. Almost 35% of veterans experienced at least 1 military-related TBI; all were mild in severity, 40% of them were due to blast, 50% were due to some other (ie, blunt) mechanism, and 10% were due to both types of injuries. Predeployment TBIs were frequent (45% of veterans). There was strong correspondence between the BAT-L and the OSU-TBI-ID (Cohen κ = 0.89; Kendall τ-b = 0.95). Interrater reliability of the BAT-L was strong (κs >0.80). CONCLUSIONS: The BAT-L is a valid instrument with which to assess TBI across a service member's lifetime and captures the varied and complex nature of brain injuries across OEF/OIF veterans' life span.