A case-control study examining whether neurological deficits and PTSD in combat veterans are related to episodes of mild TBI

The Co-Occurrence of Post-Traumatic Stress Disorder and Depression in Individuals with and without Traumatic Brain Injury: A Comprehensive Investigation

Post-traumatic stress disorder (PTSD) is a prevalent psychiatric disorder that often occurs following war trauma. Despite its high prevalence, there is still a lack of comprehensive understanding regarding the mechanisms underlying its progression and treatment resistance. Recent research has shed light on the biological basis of PTSD, with neuroimaging studies revealing altered brain connectivity patterns in affected individuals. In war contexts, traumatic brain injury (TBI) is a common occurrence and is associated with a high prevalence of PTSD. This study aimed to compare the severity of PTSD and depression in patients with and without a history of TBI to shed light on the impact of comorbid TBI on the presentation of PTSD symptoms. To achieve this goal, a cross-sectional study was conducted involving a sample of 60 outpatients who were diagnosed with both PTSD and Depressive Disorder. The inclusion criteria required participants to meet the diagnostic criteria for both disorders using validated tools. The severities of PTSD and depressive symptoms were assessed using scales that have been widely used and validated in previous research. By utilizing these standardized assessment tools, this study aimed to ensure the reliability and validity of the obtained data. The results of this study revealed that patients with comorbid PTSD and TBI exhibited a significantly higher severity of PTSD symptoms compared to those with PTSD only. Specifically, the comorbid group demonstrated higher ratings of symptom intensity across all symptom clusters. These findings are consistent with previous research that has highlighted the impact of comorbid TBI on the intensity and persistence of PTSD symptoms. When controlling for PTSD severity, no significant differences were observed in the severity of depressive symptoms between the two groups. This suggests that the increased depressive symptoms observed in the comorbid group may be primarily driven by the presence of more intense PTSD symptoms rather than TBI per se. The findings highlight the need for an accurate diagnosis of TBI in individuals with PTSD to guide appropriate treatment interventions. Further research is warranted to delve into the underlying mechanisms that contribute to the interaction between TBI and PTSD and to develop targeted interventions for individuals with comorbid PTSD and TBI.

A pilot study of olfactory function in veterans with a history of deployment-related mild traumatic brain injury

Olfactory impairment in military populations is highly prevalent and often attributed to the long-term effects of mild traumatic brain injury (mTBI) and chronic psychiatric disorders. The main goal of this investigation was to examine olfactory function in a cohort of combat veterans using a quantitative smell test.Participants underwent a neurological examination, completed performance validity testing (PVT), provided deployment history, and their medical records were reviewed.Participants were 38 veterans with a deployment-related mTBI who passed the PVT and did not have ongoing substance misuse issues. Olfactory examination revealed normosmia in 20 participants and various degrees of deficit in 18. The groups did not differ in demographics, post-injury interval, or current clinical (non-psychiatric) conditions. Participants with hyposmia frequently reported being exposed to a higher number of blasts and being positioned closer to the nearest primary blast, and more often endorsed a period of loss of consciousness after the most serious mTBI. In addition, they more often reported tympanic membrane perforation, extracranial injuries, and histories of both blast and blunt force mTBI. Comorbid diagnoses of posttraumatic stress disorder, depression, chronic headaches, and pain were more common among them as well.Several blast exposure and injury-related characteristics increase the likelihood of long-term olfactory impartments, comorbid psychiatric conditions, and chronic pain among veterans with history of deployment-related mTBI. Notably, none of the participants with hyposmia had a clinical diagnosis of olfactory dysfunction or were receiving service-connected disability for loss of sense of smell at the time of their assessment.

Relationship Between Headache Characteristics and a Remote History of TBI in Veterans: A 10-Year Retrospective Chart Review

BACKGROUND AND OBJECTIVES

The objective of this work was to examine the association between deployment-related traumatic brain injury (TBI) severity, frequency, and other injury characteristics with headache outcomes in veterans evaluated at a Veterans Administration (VA) polytrauma support clinic.

METHODS

We conducted a retrospective chart review of 594 comprehensive TBI evaluations between 2011 and 2021. Diagnostic criteria were based on the Department of Defense/VA Consensus-Based Classification of Closed TBI. Adjusted odds ratios (AORs) and 95% CIs were estimated for headache prevalence (logistic), headache severity (ordinal), and prevalence of migraine-like features (logistic) with multiple regression analysis. Regression models were adjusted for age, sex, race/ethnicity, time since injury, and mental health diagnoses.

RESULTS

TBI severity groups were classified as sub concussive exposure (n = 189) and mild (n = 377), moderate (n = 28), and severe TBI (n = 0). Increased headache severity was reported in veterans with mild TBI (AOR 1.72 [95% CI 1.15, 2.57]) and moderate TBI (AOR 3.89 [1.64, 9.15]) compared to those with subconcussive exposure. A history of multiple mild TBIs was associated with more severe headache (AOR 2.47 [1.34, 4.59]) and migraine-like features (AOR 5.95 [2.55, 13.77]). No differences were observed between blast and nonblast injuries; however, greater headache severity was reported in veterans with both primary and tertiary blast effects (AOR 2.56 [1.47, 4.49]). Alteration of consciousness (AOC) and posttraumatic amnesia (PTA) >30 minutes were associated with more severe headache (AOR 3.37 [1.26, 9.17] and 5.40 [2.21, 13.42], respectively). The length of time between the onset of last TBI and the TBI evaluation was associated with headache severity (AOR 1.09 [1.02, 1.17]) and prevalence of migraine-like features (AOR 1.27 [1.15, 1.40]). Last, helmet use was associated with less severe headache (AOR 0.42 [0.23, 0.75]) and lower odds of migraine-like features (AOR 0.45 [0.21, 0.98]).

DISCUSSION

Our data support the notion of a dose-response relationship between TBI severity and headache outcomes. A history of multiple mild TBIs and longer duration of AOC and PTA are unique risk factors for poor headache outcomes in veterans. Furthermore, this study sheds light on the poor headache outcomes associated with subconcussive exposure. Past TBI characteristics should be considered when developing headache management plans for veterans.

The impact of cigarette smoking and nicotine on traumatic brain injury: a review

INTRODUCTION

Traumatic Brain Injury (TBI) and tobacco smoking are both serious public health problems. Many people with TBI also smoke. Nicotine, a component of tobacco smoke, has been identified as a premorbid neuroprotectant in other neurological disorders. This study aims to provide better understanding of relationships between tobacco smoking and nicotine use and effect on outcome/recovery from TBI.

METHODS

PubMed database, SCOPUS, and PTSDpub were searched for relevant English-language papers.

RESULTS

Twenty-nine human clinical studies and nine animal studies were included. No nicotine-replacement product use in human TBI clinical studies were identified. While smoking tobacco prior to injury can be harmful primarily due to systemic effects that can compromise brain function, animal studies suggest that nicotine as a pharmacological agent may augment recovery of cognitive deficits caused by TBI.

CONCLUSIONS

While tobacco smoking before or after TBI has been associated with potential harms, many clinical studies downplay correlations for most expected domains. On the other hand, nicotine could provide potential treatment for cognitive deficits following TBI by reversing impaired signaling pathways in the brain including those involving nAChRs, TH, and dopamine. Future studies regarding the impact of cigarette smoking and vaping on patients with TBI are needed .

Change in Learning and Memory Partially Mediates Effects of Compensatory Cognitive Training on Self-Reported Cognitive Symptoms

OBJECTIVE

To examine associations among compensatory cognitive training (CCT), objective cognitive functioning, and self-reported cognitive symptoms. We examined whether change in objective cognitive functioning associated with participation in CCT at 10-week follow-up mediates change in self-reported cognitive symptoms associated with CCT at 15-week follow-up.

SETTING

Three VA outpatient mental health clinics.

PARTICIPANTS

Veterans with a history of mild traumatic brain injury who reported cognitive deficits.

DESIGN

Randomized controlled trial post hoc causal mediation analysis.

MAIN MEASURES

Self-reported cognitive symptoms were measured by the Prospective-Retrospective Memory Questionnaire and the Multiple Sclerosis Neuropsychological Screening Questionnaire. Objective cognitive functioning was measured using a battery of neuropsychological tests.

RESULTS

Improvement on the Hopkins Verbal Learning Test-Revised (HVLT-R) Delayed Recall test mediated the association between participation in CCT and decrease in the Prospective-Retrospective Memory Questionnaire total score. Improvement on the HVLT-R Total Recall and HVLT-R Delayed Recall tests both meditated the association between participation in CCT and decrease in the Multiple Sclerosis Neuropsychological Screening Questionnaire total score. No other measures of objective cognitive functioning were significant mediators.

CONCLUSION

Patients' perceptions of cognitive symptom improvement due to CCT are partially mediated by learning and memory, though these subjective improvements occur regardless of other changes in objective cognitive functioning associated with CCT.

Screening for Poor Self-Reported Sleep Quality at 12 Weeks in Post-Mild Traumatic Brain Injury Patients Using the HF-Age-Gender (HAG) Index

To identify a screening tool for poor self-reported sleep quality at 12 weeks according to non-invasive measurements and patients' characteristics in the first week after mild traumatic brain injury (mTBI), data from 473 mTBI participants were collected and follow-ups were performed at 12 weeks. Patients with previous poor self-reported sleep quality prior to the injury were excluded. Patients were then divided into two groups at 12 weeks according to the Pittsburgh Sleep Quality Index based on whether or not they experienced poor sleep quality. The analysis was performed on personal profiles and heart rate variability (HRV) for 1 week. After analyzing the non-invasive measurements and characteristics of mTBI patients who did not complain of poor sleep quality, several factors were found to be relevant to the delayed onset of poor sleep quality, including age, gender, and HRV measurements. The HRV-age-gender (HAG) index was proposed and found to have 100% sensitivity (cut-off, 7; specificity, 0.537) to predicting whether the patient will experience poor sleep quality after mTBI at the 12-week follow-up. The HAG index helps us to identify patients with mTBI who have no sleep quality complaints but are prone to developing poor self-reported sleep quality. Additional interventions to improve sleep quality would be important for these particular patients in the future.

Investigation of the Relationship Between Frequency of Blast Exposure, mTBI History, and Post-traumatic Stress Symptoms

INTRODUCTION

Post-traumatic stress disorder (PTSD) and mild traumatic brain injury (mTBI) are common conditions among military personnel that frequently co-occur. This study investigated relationships between self-reported blast exposure, mTBI history, and current post-traumatic stress (PTS) symptoms in a population of active duty service members (n = 202) from the Intensive Outpatient Program at the National Intrepid Center of Excellence.

MATERIALS AND METHODS

Participants were divided into four mTBI groups (0, 1, 2, and 3+) and four blast exposure groups (0-10, 11-100, 101-1,000, and 1,000+). Self-reported lifetime mTBI and blast history were obtained via the Ohio State University TBI Identification Method. PTSS severity was obtained via the PTSD Checklist-Civilian version (PCL-C). Several secondary measures of depression, anxiety, chronic mTBI symptoms, and sleep were also assessed.

RESULTS

The total PCL-C scores differed significantly between mTBI groups, with significant differences detected between the 0/1 mTBI groups and the 3+ mTBI groups. Similar group differences were noted across the three PCL-C subgroup scores (avoidance, re-experiencing, and hyperarousal); however, when comparing the proportion of group participants meeting DSM-IV criteria for each symptom cluster, significant differences between mTBI groups were only noted for avoidance (P = .002). No group differences were noted in PTS symptom severity or distribution between blast groups.

CONCLUSIONS

This study demonstrates an association between lifetime mTBI history and PTS symptom severity and distribution but failed to identify the significant group in self-reported symptoms between the blast exposure groups. Results suggest that additional research is needed to understand the neurobiological mechanism behind these associations and the need for the development of precise assessment tools that are able to more accurately quantify significant lifetime sub-concussive and blast exposures experienced by service members in training and combat operations.

A Decade of mTBI Experience: What Have We Learned? A Summary of Proceedings From a NATO Lecture Series on Military mTBI

Mild traumatic brain injury (mTBI, also known as a concussion) as a consequence of battlefield blast exposure or blunt force trauma has been of increasing concern to militaries during recent conflicts. This concern is due to the frequency of exposure to improvised explosive devices for forces engaged in operations both in Iraq and Afghanistan coupled with the recognition that mTBI may go unreported or undetected. Blasts can lead to mTBI through a variety of mechanisms. Debate continues as to whether exposure to a primary blast wave alone is sufficient to create brain injury in humans, and if so, exactly how this occurs with an intact skull. Resources dedicated to research in this area have also varied substantially among contributing NATO countries. Most of the research has been conducted in the US, focused on addressing uncertainties in management practices. Development of objective diagnostic tests should be a top priority to facilitate both diagnosis and prognosis, thereby improving management. It is expected that blast exposure and blunt force trauma to the head will continue to be a potential source of injury during future conflicts. An improved understanding of the effects of blast exposure will better enable military medical providers to manage mTBI cases and develop optimal protective measures. Without the immediate pressures that come with a high operational tempo, the time is right to look back at lessons learned, make full use of available data, and modify mitigation strategies with both available evidence and new evidence as it comes to light. Toward that end, leveraging our cooperation with the civilian medical community is critical because the military experience over the past 10 years has led to a renewed interest in many similar issues pertaining to mTBI in the civilian world. Such cross-fertilization of knowledge will undoubtedly benefit all. This paper highlights similarities and differences in approach to mTBI patient care in NATO and partner countries and provides a summary of and lessons learned from a NATO lecture series on the topic of mTBI, demonstrating utility of having patients present their experiences to a medical audience, linking practical clinical care to policy approaches.

(-)-Phenserine and the prevention of pre-programmed cell death and neuroinflammation in mild traumatic brain injury and Alzheimer's disease challenged mice

Mild traumatic brain injury (mTBI) is a risk factor for neurodegenerative disorders, such as Alzheimer's disease (AD) and Parkinson's disease (PD). TBI-derived neuropathologies are promoted by inflammatory processes: chronic microgliosis and release of pro-inflammatory cytokines that further promote neuronal dysfunction and loss. Herein, we evaluated the effect on pre-programmed cell death/neuroinflammation/synaptic integrity and function of (-)-Phenserine tartrate (Phen), an agent originally developed for AD. This was studied at two clinically translatable doses (2.5 and 5.0 mg/kg, BID), in a weight drop (concussive) mTBI model in wild type (WT) and AD APP/PSEN1 transgenic mice. Phen mitigated mTBI-induced cognitive impairment, assessed by Novel Object Recognition and Y-maze behavioral paradigms, in WT mice. Phen fully abated mTBI-induced neurodegeneration, evaluated by counting Fluoro-Jade C-positive (FJC+) cells, in hippocampus and cortex of WT mice. In APP/PSEN1 mice, degenerating cell counts were consistently greater across all experimental groups vs. WT mice. mTBI elevated FJC+ cell counts vs. the APP/PSEN1 control (sham) group, and Phen similarly mitigated this. Anti-inflammatory effects on microglial activation (IBA1-immunoreactivity (IR)) and the pro-inflammatory cytokine TNF-α were evaluated. mTBI increased IBA1-IR and TNF-α/IBA1 colocalization vs. sham, both in WT and APP/PSEN1 mice. Phen decreased IBA1-IR throughout hippocampi and cortices of WT mice, and in cortices of AD mice. Phen, likewise, reduced levels of IBA1/TNF-α-IR colocalization volume across all areas in WT animals, with a similar trend in APP/PSEN1 mice. Actions on astrocyte activation by mTBI were followed by evaluating GFAP, and were similarly mitigated by Phen. Synaptic density was evaluated by quantifying PSD-95+ dendritic spines and Synaptophysin (Syn)-IR. Both were significantly reduced in mTBI vs. sham in both WT and APP/PSEN1 mice. Phen fully reversed the PSD-95+ spine loss in WT and Syn-IR decrease in both WT and APP/PSEN1 mice. To associate immunohistochemical changes in synaptic markers with function, hippocampal long term potentiation (LTP) was induced in WT mice. LTP was impaired by mTBI, and this impairment was mitigated by Phen. In synopsis, clinically translatable doses of Phen ameliorated mTBI-mediated pre-programmed cell death/neuroinflammation/synaptic dysfunction in WT mice, consistent with fully mitigating mTBI-induced cognitive impairments. Phen additionally demonstrated positive actions in the more pathologic brain microenvironment of AD mice, further supporting consideration of its repurposing as a treatment for mTBI.

Structural and Functional Brain Alterations in Post-traumatic Headache Attributed to Mild Traumatic Brain Injury: A Narrative Review

Introduction: By definition, post-traumatic headache (PTH) attributed to mild traumatic brain injury (mTBI) is not associated with brain structural abnormalities that are seen on routine clinical inspection of brain images. However, subtle brain structural abnormalities, as well as functional abnormalities, detected via research imaging techniques yield insights into the pathophysiology of PTH. The objective of this manuscript is to summarize published findings regarding research imaging of the brain in PTH attributed to mTBI.

Methods:For this narrative review, PubMed was searched using the terms “post-traumatic headache” or “post-concussion headache” and “imaging” or “magnetic resonance imaging” or “research imaging” or “positron emission tomography”. Articles were chosen for inclusion based on their relevance to the topic.

Results: Ten articles were ultimately included within this review. The studies investigated white matter tract integrity and functional connectivity in acute PTH, structural measures, white matter tract integrity, cerebral blood flow, and functional connectivity in persistent PTH (PPTH), and proton spectroscopy in both acute and persistent PTH. The articles demonstrate that acute and persistent PTH are associated with abnormalities in brain structure, that acute and persistent PTH are also associated with abnormalities in brain function, that it might be possible to predict the persistence of PTH using brain imaging findings, and that there are differences in imaging findings when comparing PTH to healthy controls and when comparing PTH to migraine. Although it is not entirely clear if the imaging findings are directly attributable to PTH as opposed to the underlying TBI or other post-TBI symptoms, correlations between the imaging findings with headache frequency and headache resolution suggest a true relationship between the imaging findings and PTH.

Conclusions: PTH attributed to mTBI is associated with abnormalities in brain structure and function that can be detected via research imaging. Additional studies are needed to determine the specificity of the findings for PTH, to differentiate findings attributed to PTH from those attributed to the underlying TBI and coexistent post-TBI symptoms, and to determine the accuracy of imaging findings for predicting the development of PPTH.

(-)-Phenserine Ameliorates Contusion Volume, Neuroinflammation, and Behavioral Impairments Induced by Traumatic Brain Injury in Mice

Traumatic brain injury (TBI), a major cause of mortality and morbidity, affects 10 million people worldwide, with limited treatment options. We have previously shown that (-)-phenserine (Phen), an acetylcholinesterase inhibitor originally designed and tested in clinical phase III trials for Alzheimer's disease, can reduce neurodegeneration after TBI and reduce cognitive impairments induced by mild TBI. In this study, we used a mouse model of moderate to severe TBI by controlled cortical impact to assess the effects of Phen on post-trauma histochemical and behavioral changes. Animals were treated with Phen (2.5 mg/kg, IP, BID) for 5 days started on the day of injury and the effects were evaluated by behavioral and histological examinations at 1 and 2 weeks after injury. Phen significantly attenuated TBI-induced contusion volume, enlargement of the lateral ventricle, and behavioral impairments in motor asymmetry, sensorimotor functions, motor coordination, and balance functions. The morphology of microglia was shifted to an active from a resting form after TBI, and Phen dramatically reduced the ratio of activated to resting microglia, suggesting that Phen also mitigates neuroinflammation after TBI. While Phen has potent anti-acetylcholinesterase activity, its (+) isomer Posiphen shares many neuroprotective properties but is almost completely devoid of anti-acetylcholinesterase activity. We evaluated Posiphen at a similar dose to Phen and found similar mitigation in lateral ventricular size increase, motor asymmetry, motor coordination, and balance function, suggesting the improvement of these histological and behavioral tests by Phen treatment occur via pathways other than anti-acetylcholinesterase inhibition. However, the reduction of lesion size and improvement of sensorimotor function by Posiphen were much smaller than with equivalent doses of Phen. Taken together, these results show that post-injury treatment with Phen over 5 days significantly ameliorates severity of TBI. These data suggest a potential development of this compound for clinical use in TBI therapy.

Pharmacokinetics and efficacy of PT302, a sustained-release Exenatide formulation, in a murine model of mild traumatic brain injury

Traumatic brain injury (TBI) is a neurodegenerative disorder for which no effective pharmacological treatment is available. Glucagon-like peptide 1 (GLP-1) analogues such as Exenatide have previously demonstrated neurotrophic and neuroprotective effects in cellular and animal models of TBI. However, chronic or repeated administration was needed for efficacy. In this study, the pharmacokinetics and efficacy of PT302, a clinically available sustained-release Exenatide formulation (SR-Exenatide) were evaluated in a concussive mild (m)TBI mouse model. A single subcutaneous (s.c.) injection of PT302 (0.6, 0.12, and 0.024 mg/kg) was administered and plasma Exenatide concentrations were time-dependently measured over 3 weeks. An initial rapid regulated release of Exenatide in plasma was followed by a secondary phase of sustained-release in a dose-dependent manner. Short- and longer-term (7 and 30 day) cognitive impairments (visual and spatial deficits) induced by weight drop mTBI were mitigated by a single post-injury treatment with Exenatide delivered by s.c. injection of PT302 in clinically translatable doses. Immunohistochemical evaluation of neuronal cell death and inflammatory markers, likewise, cross-validated the neurotrophic and neuroprotective effects of SR-Exenatide in this mouse mTBI model. Exenatide central nervous system concentrations were 1.5% to 2.0% of concomitant plasma levels under steady-state conditions. These data demonstrate a positive beneficial action of PT302 in mTBI. This convenient single, sustained-release dosing regimen also has application for other neurological disorders, such as Alzheimer's disease, Parkinson's disease, multiple system atrophy and multiple sclerosis where prior preclinical studies, likewise, have demonstrated positive Exenatide actions.

Using Next-Generation Sequencing Transcriptomics To Determine Markers of Post-traumatic Symptoms: Preliminary Findings from a Post-deployment Cohort of Soldiers

Post-traumatic stress disorder is a concerning psychobehavioral disorder thought to emerge from the complex interaction between genetic and environmental factors. For soldiers exposed to combat, the risk of developing this disorder is twofold and diagnosis is often late, when much sequela has set in. To be able to identify and diagnose in advance those at “risk” of developing post-traumatic stress disorder, would greatly taper the gap between late sequelae and treatment. Therefore, this study sought to determine whether the transcriptome can be used to track the development of post-traumatic stress disorder in this unique and susceptible cohort of individuals. Gene expression levels in peripheral blood samples from 85 Canadian infantry soldiers (n = 58 participants negative for symptoms of post-traumatic stress disorder and n = 27 participants with symptoms of post-traumatic stress disorder) following return from deployment to Afghanistan were determined using RNA sequencing technology. Count-based gene expression quantification, normalization and differential analysis (with thorough correction for confounders) revealed genes associated to PTSD; LRP8 and GOLM1. These preliminary results provide a proof-of-principle for the diagnostic utility of blood-based gene expression profiles for tracking symptoms of post-traumatic stress disorder in soldiers returning from tour. It is also the first to report transcriptome-wide expression profiles alongside a post-traumatic symptom checklist.

Neuronal Enriched Extracellular Vesicle Proteins as Biomarkers for Traumatic Brain Injury

Traumatic brain injury (TBI) is a major cause of injury-related death throughout the world and lacks effective treatment. Surviving TBI patients often develop neuropsychiatric symptoms, and the molecular mechanisms underlying the neuronal damage and recovery following TBI are not well understood. Extracellular vesicles (EVs) are membranous nanoparticles that are divided into exosomes (originating in the endosomal/multi-vesicular body [MVB] system) and microvesicles (larger EVs produced through budding of the plasma membrane). Both types of EVs are generated by all cells and are secreted into the extracellular environment, and participate in cell-to-cell communication and protein and RNA delivery. EVs enriched for neuronal origin can be harvested from peripheral blood samples and their contents quantitatively examined as a window to follow potential changes occurring in brain. Recent studies suggest that the levels of exosomal proteins and microRNAs (miRNAs) may represent novel biomarkers to support the clinical diagnosis and potential response to treatment for neurological disorders. In this review, we focus on the biogenesis of EVs, their molecular composition, and recent advances in research of their contents as potential diagnostic tools for TBI.

Premorbid IQ Predicts Postconcussive Symptoms in OEF/OIF/OND Veterans with mTBI

Objective

Extant literature has demonstrated that symptoms of postconcussive syndrome (PCS) persist well beyond the expected 3-month post-injury recovery period in a minority of individuals with mild traumatic brain injury (mTBI). Suboptimal performance on validity measures and pre- and post-injury psychosocial stressors - rather than actual mTBI or current cognitive functioning - have been identified as predictors of chronic PCS. Whether premorbid IQ has any influence on chronic PCS has been understudied, in the context of established psychogenic etiologies.

Method

The sample included 31 veterans, who underwent mTBI neuropsychological evaluations six or more months post-injury in a VA outpatient neuropsychology clinic. A two-step multiple linear regression was conducted to examine the effects on the outcome variable, PCS (Neurobehavioral Symptom Inventory), of the following predictors: cognitive functioning (Repeatable Battery for the Assessment of Neuropsychological Status; Attention, Immediate Memory, and Delayed Memory Indices), performance validity, depression (Beck Depression Inventory-Second Edition), posttraumatic stress disorder (PTSD Checklist, Civilian Version), quality of sleep (Pittsburgh Sleep Quality Index), pain (Brief Pain Inventory), education, and Premorbid IQ (Wechsler Test of Adult Reading).

Results

The overall regression model containing all nine predictor variables was statistically significant. Depression (p < .05) and premorbid IQ (p < .05) were the most salient predictors of chronic PCS; in that lower premorbid IQ and greater endorsed symptoms of depression were associated with higher PCS scores. In Step 2 of the multiple linear regression, the WTAR explained an additional 6.7% of the variance in PCS after controlling for psychosocial stressors and current cognitive ability.

Conclusion

The findings support premorbid IQ as a unique and relevant predictor of chronic PCS, with significance variance accounted for beyond education, cognitive functioning, and psychosocial variables. Given the predictive relationship between premorbid IQ and PCS, adapting postconcussive interventions to meet the specific needs of individuals with varying levels of intellect may be important in minimizing ongoing symptomatology.

Interactive effects of cumulative lifetime traumatic brain injuries and combat exposure on posttraumatic stress among deployed military personnel

Growing research links Traumatic Brain Injury (TBI) with greater posttraumatic stress disorder (PTSD) symptoms. Much of this research has focused on the influence of the presence or severity of a single TBI while neglecting the potential cumulative effects of multiple TBIs incurred across an individual's lifetime on combat-related PTSD. The present study addressed this gap using a sample of 157 military service members and 4 civilian contractors who underwent structured TBI interviews at a military hospital in Iraq and completed the Combat Experiences Scale (CES) and Posttraumatic Checklist - Military (PCL-M). Results indicated that a greater number of lifetime TBIs were associated with greater PTSD symptoms when accounting for the presence and severity of a recent, deployment-related TBI. Additionally, a significant interaction of number of lifetime TBIs and combat exposure emerged, indicating that exposure to combat yielded greater PTSD symptoms among those with multiple lifetime TBIs compared to those with one or zero lifetime TBIs. These data suggest that incurring multiple TBIs may amplify the link between combat exposure and PTSD and underscore the need to screen for lifetime TBI history.

Neurobehavioral Characteristics of Older Veterans With Remote Traumatic Brain Injury

OBJECTIVE

While traumatic brain injury (TBI) is common across the life span, the detailed neurobehavioral characteristics of older adults with prior TBI remain unclear. Our goal was to compare the clinical profile of older independently living veterans with and without prior TBI.

SETTING

Two veterans' retirement communities.

PARTICIPANTS

Seventy-five participants with TBI and 71 without (mean age = 78 years).

DESIGN

Cross-sectional.

MAIN MEASURES

TBI history was determined by the Ohio State University TBI Questionnaire. We assessed psychiatric and medical history via interviews and chart review and conducted measures assessing functional/lifestyle, psychiatric, and cognitive outcomes. Regression analyses (adjusted for demographics, diabetes, prior depression, substance abuse, and site) were performed to compare between TBI and non-TBI participants.

RESULTS

Compared with veterans without TBI, those with TBI had greater functional impairment (adjusted P = .05), endorsed more current depressive (adjusted P = .04) and posttraumatic stress disorder symptoms (adjusted P = .01), and had higher rates of prior depression and substance abuse (both adjusted Ps < .01). While composite memory and language scores did not differ between groups, participants with TBI performed worse on tests of executive functioning/processing speed (adjusted P = .01).

CONCLUSIONS

Our results suggest that TBI may have adverse long-term neurobehavioral consequences and that TBI-exposed adults may require careful screening and follow-up.

Suicidal Ideation After Mild Traumatic Brain Injury: A Consecutive Canadian Sample

This study aims to elucidate psychosocial and injury features contributing to SI following concussion or mild traumatic brain injury (mTBI) and the time course for its development. Between 1998 and 2012, a sample of 871 patients referred to a follow-up clinic after concussion treatment in an urban tertiary care ED were consecutively offered enrollment at 3 months post injury. Data from psychiatric and social-demographic assessments were consecutively collected at 2 visits (3 and 6 months after injury) respectively. Chi-square and t-tests were performed to identify associations between variables related with SI. Logistic regression analysis was performed to identify factors independently associated. During the enrolment period, 2,296 patients with mTBI presented to the ED. 871 adults completed psychiatric and social demographic clinic assessments at 3 months, and 500 returned at 6 months. Suicidal ideation was expressed by 6.3% at 3 months and 8.2% at 6 months. Regression models showed SI independently associated with: speaking English as a second language (ESL) and injury mechanism (MVC passenger) at 3 and 6 months; and history of depression and marital status at 3 months only. SI is common 3 months after mTBI, and appears more at 6 month follow up. These findings suggest earlier screening for predisposing factors and closer monitoring of those at risk for suicidality.

Olfaction as a soldier-- a review of the physiology and its present and future use in the military

Olfaction is one of our 5 main qualitative sensory abilities. In this review, we have examined the physiology of olfaction from the olfactory receptor to the brain. Through analyzing the physiology of olfaction, we have found that the biochemistry of olfactory nerve stimulation is unique from that of other similar pathways. Upon receiving large amounts of input from the olfactory nerve, the olfactory bulb, followed by several layers of centrifugal and centripetal processing in the brain, has to sort the information from the input as well as integrate it with other inputs from the brain to develop a coherent understanding of the input. We then examined the implications of olfaction in the military, the practical applications of electronic noses and problems associated with injury to olfaction that could affect compensation and combat worthiness of a soldier following injury. In the military, olfaction can allow the army to perform at its best through 4 main methods, namely ensuring olfaction is consistent with other dimensions of perception (ensuring optimal olfaction ability in all soldiers in combat), understanding the impact of different common combat environments on the sense of smell, utilizing odor as a defense mechanism and using olfactory aids when necessary. Electronic noses are olfactory aids that have a large potential in the military ranging from saving lives through the detection of explosives to potential methods for improving combustion efficiency. There are several problems associated with injury to olfaction that should be considered when deciding on compensation and combat worthiness of the soldier following an injury.

Pathophysiological links between traumatic brain injury and post-traumatic headaches

This article reviews possible ways that traumatic brain injury (TBI) can induce migraine-type post-traumatic headaches (PTHs) in children, adults, civilians, and military personnel. Several cerebral alterations resulting from TBI can foster the development of PTH, including neuroinflammation that can activate neural systems associated with migraine. TBI can also compromise the intrinsic pain modulation system and this would increase the level of perceived pain associated with PTH. Depression and anxiety disorders, especially post-traumatic stress disorder (PTSD), are associated with TBI and these psychological conditions can directly intensify PTH. Additionally, depression and PTSD alter sleep and this will increase headache severity and foster the genesis of PTH. This article also reviews the anatomic loci of injury associated with TBI and notes the overlap between areas of injury associated with TBI and PTSD.

Post-traumatic headaches

Chronic pain, especially headache, is an exceedingly common complication of traumatic brain injury (TBI). In fact, paradoxically, the milder the TBI, the more likely one is to develop headaches. The environment of injury and the associated comorbidities can have a significant impact on the frequency and severity of headaches and commonly serve to direct management of the headaches. Trauma likely contributes to the development of headaches via alterations in neuronal signaling, inflammation, and musculoskeletal changes. The clinical picture of the patient with post-traumatic headaches is often that of a mixed headache disorder with features of tension-type headaches as well as migrainous headaches. Treatment of these headaches is thus often guided by the predominant characteristics of the headaches and can include pharmacologic and nonpharmacologic strategies. Pharmacologic therapies include both abortive and prophylactic agents with prophylaxis targeting comorbidities, primarily impaired sleep. Nonpharmacologic interventions for post-traumatic headaches include thermal and physical modalities as well as cognitive behavioral approaches. As with many postconcussive symptoms, headaches can lessen with time but in up to 25% of patients, chronic headaches are long-term residua.

Olfactory Function and Associated Clinical Correlates in Former National Football League Players

Professional American football players incur thousands of repetitive head impacts (RHIs) throughout their lifetime. The long-term consequences of RHI are not well characterized, but may include olfactory dysfunction. RHI has been associated with changes to brain regions involved in olfaction, and olfactory impairment is common after traumatic brain injury. Olfactory dysfunction is a frequent early sequelae of neurodegenerative diseases (e.g., Alzheimer's disease), and RHI is associated with the neurodegenerative disease, chronic traumatic encephalopathy (CTE). We examined olfaction, and its association with clinical measures, in former National Football League (NFL) players. Ninety-five former NFL players (ages 40-69) and 28 same-age controls completed a neuropsychological and neuropsychiatric evaluation as part of a National Institutes of Health-funded study. The Brief Smell Identification Test (B-SIT) assessed olfaction. Principal component analysis generated a four-factor structure of the clinical measures: behavioral/mood, psychomotor speed/executive function, and verbal and visual memory. Former NFL players had worse B-SIT scores relative to controls (p = 0.0096). A B-SIT cutoff of 11 had the greatest accuracy (c-statistic = 0.61) and specificity (79%) for discriminating former NFL players from controls. In the former NFL players, lower B-SIT scores correlated with greater behavioral/mood impairment (p = 0.0254) and worse psychomotor speed/executive functioning (p = 0.0464) after controlling for age and education. Former NFL players exhibited lower olfactory test scores relative to controls, and poorer olfactory test performance was associated with worse neuropsychological and neuropsychiatric functioning. Future work that uses more-comprehensive tests of olfaction and structural and functioning neuroimaging may improve understanding on the association between RHI and olfaction.

Traumatic Brain Injury as a Disorder of Brain Connectivity

OBJECTIVES

Recent advances in neuroimaging methodologies sensitive to axonal injury have made it possible to assess in vivo the extent of traumatic brain injury (TBI) -related disruption in neural structures and their connections. The objective of this paper is to review studies examining connectivity in TBI with an emphasis on structural and functional MRI methods that have proven to be valuable in uncovering neural abnormalities associated with this condition.

METHODS

We review studies that have examined white matter integrity in TBI of varying etiology and levels of severity, and consider how findings at different times post-injury may inform underlying mechanisms of post-injury progression and recovery. Moreover, in light of recent advances in neuroimaging methods to study the functional connectivity among brain regions that form integrated networks, we review TBI studies that use resting-state functional connectivity MRI methodology to examine neural networks disrupted by putative axonal injury.

RESULTS

The findings suggest that TBI is associated with altered structural and functional connectivity, characterized by decreased integrity of white matter pathways and imbalance and inefficiency of functional networks. These structural and functional alterations are often associated with neurocognitive dysfunction and poor functional outcomes.

CONCLUSIONS

TBI has a negative impact on distributed brain networks that lead to behavioral disturbance.

Olfactory impairment and traumatic brain injury in blast-injured combat troops: a cohort study

OBJECTIVE

To determine whether a structured and quantitative assessment of differential olfactory performance-recognized between a blast-injured traumatic brain injury (TBI) group and a demographically comparable blast-injured control group-can serve as a reliable antecedent marker for preclinical detection of intracranial neurotrauma.

METHODS

We prospectively and consecutively enrolled 231 polytrauma inpatients, acutely injured from explosions during combat operations in either Afghanistan or Iraq and requiring immediate stateside evacuation and sequential admission to our tertiary care medical center over a 2½-year period. This study correlates olfactometric scores with both contemporaneous neuroimaging findings as well as the clinical diagnosis of TBI, tabulates population-specific incidence data, and investigates return of olfactory function.

RESULTS

Olfactometric score predicted abnormal neuroimaging significantly better than chance alone (area under the curve = 0.78, 95% confidence interval [CI] 0.70-0.87). Normosmia was present in all troops with mild TBI (i.e., concussion) and all control subjects. Troops with radiographic evidence of frontal lobe injuries were 3 times more likely to have olfactory impairment than troops with injuries to other brain regions (relative risk 3.0, 95% CI 0.98-9.14). Normalization of scores occurred in all anosmic troops available for follow-up testing.

CONCLUSION

Quantitative identification olfactometry has limited sensitivity but high specificity as a marker for detecting acute structural neuropathology from trauma. When considering whether to order advanced neuroimaging, a functional disturbance with central olfactory impairment should be regarded as an important tool to inform the decision process.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that central olfactory dysfunction identifies patients with TBI who have intracranial radiographic abnormalities with a sensitivity of 35% (95% CI 20.6%-51.7%) and specificity of 100% (95% CI 97.7%-100.0%).

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

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

Effects of low-level blast exposure on the nervous system: is there really a controversy?

High-pressure blast waves can cause extensive CNS injury in human beings. However, in combat settings, such as Iraq and Afghanistan, lower level exposures associated with mild traumatic brain injury (mTBI) or subclinical exposure have been much more common. Yet controversy exists concerning what traits can be attributed to low-level blast, in large part due to the difficulty of distinguishing blast-related mTBI from post-traumatic stress disorder (PTSD). We describe how TBI is defined in human beings and the problems posed in using current definitions to recognize blast-related mTBI. We next consider the problem of applying definitions of human mTBI to animal models, in particular that TBI severity in human beings is defined in relation to alteration of consciousness at the time of injury, which typically cannot be assessed in animals. However, based on outcome assessments, a condition of "low-level" blast exposure can be defined in animals that likely approximates human mTBI or subclinical exposure. We review blast injury modeling in animals noting that inconsistencies in experimental approach have contributed to uncertainty over the effects of low-level blast. Yet, animal studies show that low-level blast pressure waves are transmitted to the brain. In brain, low-level blast exposures cause behavioral, biochemical, pathological, and physiological effects on the nervous system including the induction of PTSD-related behavioral traits in the absence of a psychological stressor. We review the relationship of blast exposure to chronic neurodegenerative diseases noting the paradoxical lowering of Abeta by blast, which along with other observations suggest that blast-related TBI is pathophysiologically distinct from non-blast TBI. Human neuroimaging studies show that blast-related mTBI is associated with a variety of chronic effects that are unlikely to be explained by co-morbid PTSD. We conclude that abundant evidence supports low-level blast as having long-term effects on the nervous system.

Post-traumatic headaches in civilians and military personnel: a comparative, clinical review

Post-traumatic headache (PTH) is the most frequent symptom after traumatic brain injury (TBI). We review the epidemiology and characterization of PTH in military and civilian settings. PTH appears to be more likely to develop following mild TBI (concussion) compared with moderate or severe TBI. PTH often clinically resembles primary headache disorders, usually migraine. For migraine-like PTH, individuals who had the most severe headache pain had the highest headache frequencies. Based on studies to date in both civilian and military settings, we recommend changes to the current definition of PTH. Anxiety disorders such as post-traumatic stress disorder (PTSD) are frequently associated with TBI, especially in military populations and in combat settings. PTSD can complicate treatment of PTH as a comorbid condition of post-concussion syndrome. PTH should not be treated as an isolated condition. Comorbid conditions such as PTSD and sleep disturbances also need to be treated. Double-blind placebo-controlled trials in PTH population are necessary to see whether similar phenotypes in the primary headache disorders and PTH will respond similarly to treatment. Until blinded treatment trials are completed, we suggest that, when possible, PTH be treated as one would treat the primary headache disorder(s) that the PTH most closely resembles.

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

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

Factors Associated with Mild Traumatic Brain Injury in Veterans and Military Personnel: A Systematic Review

A history of mild traumatic brain injury (mTBI) is common among military members who served in Operations Enduring Freedom, Iraqi Freedom, and New Dawn (OEF/OIF/OND). We completed a systematic review to describe the cognitive, mental health, physical health, functional, social, and cost consequences of mTBI in Veteran and military personnel. Of 2668 reviewed abstracts, the 31 included studies provided very low strength evidence for the questions of interest. Cognitive, physical, and mental health symptoms were commonly reported by Veterans/military members with a history of mTBI. On average, these symptoms were not significantly more common in those with a history of mTBI than in those without, although a lack of significant mean differences does not preclude the possibility that some individuals could experience substantial effects related to mTBI history. Evidence of potential risk or protective factors moderating mTBI outcomes was unclear. Although the overall strength of evidence is very low due to methodological limitations of included studies, our findings are consistent with civilian studies. Appropriate re-integration services are needed to address common comorbid conditions, such as treatment for post-traumatic stress disorder, substance use disorders, headaches, and other difficulties that Veterans and members of the military may experience after deployment regardless of mTBI history. (JINS, 2014, 20, 1-13).

Pituitary dysfunction after blast traumatic brain injury: The UK BIOSAP study

OBJECTIVE

Pituitary dysfunction is a recognized consequence of traumatic brain injury (TBI) that causes cognitive, psychological, and metabolic impairment. Hormone replacement offers a therapeutic opportunity. Blast TBI (bTBI) from improvised explosive devices is commonly seen in soldiers returning from recent conflicts. We investigated: (1) the prevalence and consequences of pituitary dysfunction following moderate to severe bTBI and (2) whether it is associated with particular patterns of brain injury.

METHODS

Nineteen male soldiers with moderate to severe bTBI (median age = 28.3 years) and 39 male controls with moderate to severe nonblast TBI (nbTBI; median age = 32.3 years) underwent full dynamic endocrine assessment between 2 and 48 months after injury. In addition, soldiers had structural brain magnetic resonance imaging, including diffusion tensor imaging (DTI), and cognitive assessment.

RESULTS

Six of 19 (32.0%) soldiers with bTBI, but only 1 of 39 (2.6%) nbTBI controls, had anterior pituitary dysfunction (p = 0.004). Two soldiers had hyperprolactinemia, 2 had growth hormone (GH) deficiency, 1 had adrenocorticotropic hormone (ACTH) deficiency, and 1 had combined GH/ACTH/gonadotrophin deficiency. DTI measures of white matter structure showed greater traumatic axonal injury in the cerebellum and corpus callosum in those soldiers with pituitary dysfunction than in those without. Soldiers with pituitary dysfunction after bTBI also had a higher prevalence of skull/facial fractures and worse cognitive function. Four soldiers (21.1%) commenced hormone replacement(s) for hypopituitarism.

INTERPRETATION

We reveal a high prevalence of anterior pituitary dysfunction in soldiers suffering moderate to severe bTBI, which was more frequent than in a matched group of civilian moderate to severe nbTBI subjects. We recommend that all patients with moderate to severe bTBI should routinely have comprehensive assessment of endocrine function.

Gender differences of postdeployment post-traumatic stress disorder among service members and veterans of the Iraq and Afghanistan conflicts

Despite the marked expansion of roles for women in the US military over the last decade, whether differences by gender exist in regard to the development of mental health conditions postdeployment is unclear. This comprehensive review of the literature (2001-2012) examined whether US servicewomen were more likely than men to experience post-traumatic stress disorder (PTSD) after returning from deployments to the Iraq and Afghanistan conflicts. Findings from 18 studies from 8 unique study populations were reviewed. Seven studies found that women had a higher risk for screening positive for PTSD compared with men, including prospectively designed studies that evaluated new-onset PTSD among members from all service branches. Although results from studies with Veterans Affairs samples found women at decreased risk in 4 analyses, these studies used the same source databases, were conducted in treatment-seeking populations, and were mostly unable to account for combat experience. Seven studies detected no differences by gender. In summary, women appeared to have a moderately higher risk for postdeployment PTSD, although there was a lack of consensus among the studies, and even those with the most rigorous methods were not designed specifically to evaluate potential gender differences. Given the limitations of the published literature, further research should use longitudinal study designs and comprehensive evaluations of deployment experiences while adjusting for predeployment factors to confirm that gender differences exist with regard to postdeployment PTSD.

Acute and chronic traumatic encephalopathies: pathogenesis and biomarkers

Over the past decade, public awareness of the long-term pathological consequences of traumatic brain injury (TBI) has increased. Such awareness has been stimulated mainly by reports of progressive neurological dysfunction in athletes exposed to repetitive concussions in high-impact sports such as boxing and American football, and by the rising number of TBIs in war veterans who are now more likely to survive explosive blasts owing to improved treatment. Moreover, the entity of chronic traumatic encephalopathy (CTE)--which is marked by prominent neuropsychiatric features including dementia, parkinsonism, depression, agitation, psychosis, and aggression--has become increasingly recognized as a potential late outcome of repetitive TBI. Annually, about 1% of the population in developed countries experiences a clinically relevant TBI. The goal of this Review is to provide an overview of the latest understanding of CTE pathophysiology, and to delineate the key issues that are challenging clinical and research communities, such as accurate quantification of the risk of CTE, and development of reliable biomarkers for single-incident TBI and CTE.

Military- and sports-related mild traumatic brain injury: clinical presentation, management, and long-term consequences

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This educational activity is eligible for AMA PRA Category 1 Credit ™ through February 29, 2016. The latest review of this material was January 2013.