Pathophysiological Bases of Comorbidity: Traumatic Brain Injury and Post-Traumatic Stress Disorder

Traumatic brain injury and sleep in military and veteran populations: A literature review

BACKGROUND

Traumatic brain injury (TBI) is a hallmark of wartime injury and is related to numerous sleep wake disorders (SWD), which persist long term in veterans. Current knowledge gaps in pathophysiology have hindered advances in diagnosis and treatment.

OBJECTIVE

We reviewed TBI SWD pathophysiology, comorbidities, diagnosis and treatment that have emerged over the past two decades.

METHODS

We conducted a literature review of English language publications evaluating sleep disorders (obstructive sleep apnea, insomnia, hypersomnia, parasomnias, restless legs syndrome and periodic limb movement disorder) and TBI published since 2000. We excluded studies that were not specifically evaluating TBI populations.

RESULTS

Highlighted areas of interest and knowledge gaps were identified in TBI pathophysiology and mechanisms of sleep disruption, a comparison of TBI SWD and post-traumatic stress disorder SWD. The role of TBI and glymphatic biomarkers and management strategies for TBI SWD will also be discussed.

CONCLUSION

Our understanding of the pathophysiologic underpinnings of TBI and sleep health, particularly at the basic science level, is limited. Developing an understanding of biomarkers, neuroimaging, and mixed-methods research in comorbid TBI SWD holds the greatest promise to advance our ability to diagnose and monitor response to therapy in this vulnerable population.

Sociodemographic and Health Characteristics of Hispanic Veteran Patients With Traumatic Brain Injury and Its Association to Mortality: A Pilot Study

INTRODUCTION

Traumatic brain injury (TBI) is among the most common conditions in the military. VA Caribbean Healthcare System (VACHS) patients with Traumatic Brain Injury (TBI) have a higher mortality rate than Veterans in other VA health care systems in the United States. The main goal of this study was to develop sociodemographic profiles and outline health characteristics of Hispanic patients with TBI treated at the VA Caribbean Healthcare System in a search for potential explanations to account for the higher mortality rate. This study advocates for equity in health services provided for minorities inside the militia.

MATERIALS AND METHODS

Data collected from electronic medical records and VA databases were used to create sociodemographic and health characteristics profiles, in addition to survival models. The population of the study were post 911 Veteran soldiers who had been diagnosed with TBI. Adjusted models were created to provide hazard ratios (HR) for mortality risk.

RESULTS

Out of the 16,549 files available from all 10 selected VA sites, 526 individuals were identified as treated at the VACHS. Of 526 subjects screened, 39 complied with the inclusion/exclusion criteria. Results include: 94.4% male, 48.7% between the ages of 21 and 41 years, 89.7% have depression, 66.7% have post-traumatic stress disorder (PTSD), 82.1% receive occupational therapy, 94.9% have severe headaches, 100% suffer from pain, 94.9% have memory problems, and 10.3% have had suicidal thoughts. Over 60% had a first-hand explosion experience, be it just the explosion or with another type of injury. Data showed that 33% of our patients had a Magnetic Resonance Imaging (MRI), 31% had a CT, 15.4% had a SPECT, and 2.6% had PET scan. Significant associations were found between MRIs and speech therapies, and MRIs and total comorbidities. The Cox proportional-hazards model for survival adjusted for age, gender, race/ethnicity, and comorbidities shows that VACHS Veterans diagnosed with a TBI had a higher mortality risk rate (HR 1.23 [95% CI 1.10, 1.37]) when compared to the other 9 health centers with the highest percentage of Hispanic Veterans.

CONCLUSIONS

Since explosions were the most common mechanism of injury, further research is needed into the experiences of Veterans in connection with this specific variable. A high percentage of the patients suffered from depression and PTSD. Additionally, over half of the patients had an unmeasured TBI severity. The effects these aspects have on symptomatology and how they hinder the recovery process in Hispanic patients should be examined in further detail. It is also important to highlight that family and friends' support could be key for injury treatment. This study highlights the use of the 4 types of scans (MRI, CT, PET/CT, and SPECT/CT) as ideal diagnosis tools. The alarming number of patients with suicidal thoughts should be a focus in upcoming studies. Future studies should aim to determine whether increased death rates in TBI Veterans can be linked to other United States islander territories. Concepts, such as language barriers, equal resource allocation, and the experiences of Veterans with TBIs should be further explored in this Veteran population.

ZL006 mitigates anxiety-like behaviors induced by closed head injury through modulation of the neural circuit from the medial prefrontal cortex to amygdala

Closed head injury is a prevalent form of traumatic brain injury with poorly understood effects on cortical neural circuits. Given the emotional and behavioral impairments linked to closed head injury, it is vital to uncover brain functional deficits and their driving mechanisms. In this study, we employed a robust viral tracing technique to identify the alteration of the neural pathway connecting the medial prefrontal cortex to the basolateral amygdala, and we observed the disruptions in neuronal projections between the medial prefrontal cortex and the basolateral amygdala following closed head injury. Remarkably, our results highlight that ZL006, an inhibitor targeting PSD-95/nNOS interaction, stands out for its ability to selectively reverse these aberrations. Specifically, ZL006 effectively mitigates the disruptions in neuronal projections from the medial prefrontal cortex to basolateral amygdala induced by closed head injury. Furthermore, using chemogenetic approaches, we elucidate that activating the medial prefrontal cortex projections to the basolateral amygdala circuit produces anxiolytic effects, aligning with the therapeutic potential of ZL006. Additionally, ZL006 administration effectively mitigates astrocyte activation, leading to the restoration of medial prefrontal cortex glutamatergic neuron activity. Moreover, in the context of attenuating anxiety-like behaviors through ZL006 treatment, we observe a reduction in closed head injury-induced astrocyte engulfment, which may correlate with the observed decrease in dendritic spine density of medial prefrontal cortex glutamatergic neurons.

To Calm and to Commend: Veterans' Musical Preferences Anticipating End of Life

INTRODUCTION

Since World War 1, physicians have noted the calming effects of music for military personnel experiencing "shell shock," Post Traumatic Stress Disorder (PTSD), or stress. Researchers have documented that stress or PTSD-like symptoms re-emerge for veterans at the end of life, triggered by hospital-like settings, co-occurring conditions, and debilitation. Dying veterans also face integration of their service and combat experiences into summations of their lives. In response, there has been a national movement for bedside ceremonies, often with music, to honor veterans.

MATERIALS AND METHODS

The project elicited veterans' musical preferences for calming and for music for honor services, using non-hospitalized veterans as surrogates for veterans in hospice. Respondent-driven sampling protected confidentiality and likely resulted in participants being representative of US veterans in terms of ethnicity, gender, and military branch. Recruitment materials contained all elements of informed consent, with consent collected in the introduction to the online survey. The survey had embedded links to musical performances, as well as write-in musical choices, and allowed US veterans from the Army, Air Force, Marines, and Navy to note their preferences both for music that was calming and music to be used in honor ceremonies. Online queries also asked about stress during service, usual coping strategies for stress, and current or past symptoms of PTSD. Links to hot lines were provided. The study was approved by the University of Arizona Institutional Review Board.

RESULTS

Listening to music was the most prevalent of the 20 coping mechanisms for stress in this sample of 30 veterans. Musical preferences were stable across age groups. For calming, music at resting heartbeat rhythms was chosen. Music from early adulthood or from the timelessness of the classics was selected most often. Modern music with lyrics has themes of duty, affirmation, gratitude, and relief. The nearly universal soothing effects of lullabies were recognized. For music for honor ceremonies, desires were often independent of the military branch. Patriotic songs, or songs recognizing multiple service branches, or with themes of peace and affirmation were more often chosen than music from a particular service branch.

CONCLUSION

Listening to music is a frequent coping strategy for veterans. While themes representing classical music choices are readily available in anthologies, other music chosen by this sample is not; the veterans' preferred music is rarely found in compilations of popular, movie, and TV music. Hospice and hospital intakes that document and communicate veterans' musical preferences to music therapists and therapeutic musicians may better support service men and women. Further research may examine veterans' preference for live or recorded music at end of life given the importance of meaning-making and the presence of others documented in the literature.

The Successful Use of Bilateral 2-Level Ultrasound-Guided Stellate Ganglion Block to Improve Traumatic Brain Injury Symptoms: A Retrospective Analysis of 23 Patients

PURPOSE

The purpose of the study was to determine whether performing ultrasound-guided, bilateral stellate ganglion blocks (SGBs; performed on subsequent days) improved traumatic brain injury (TBI) symptoms.

METHODS

A retrospective chart review was conducted for the time period between August 2022 and February 2023 to identify patients who received bilateral, 2-level (C6 and C4) SGBs for PTSD symptoms but who also had a history of TBI. Neurobehavioral Symptoms Inventory (NSI) scores were collected at baseline, 1 week, and 1 month post-treatment in 14 males and 9 females.

RESULTS

Out of 23 patients, 22 showed improvement in their NSI scores. NSI baseline average score was 42.7; the average score at 1 week post-treatment was 18.8; 1 month post-treatment was 20.1. This represents a 53% improvement in the NSI score between baseline and 1 month.

CONCLUSION

The use of bilateral, 2-level SGBs may be indicated in treating patients with PTSD symptoms with concomitant diagnoses of mild-to-moderate TBI.

Dizziness Directly Influences Postconcussion Symptoms and Is Predictive of Poorer Mental Health in UK Military Personnel: A Retrospective Analysis

OBJECTIVE

To investigate the contribution of dizziness to postconcussion symptoms, depression, and anxiety symptoms.

SETTING

Mild traumatic brain injury (mTBI) service, Defence Medical Rehabilitation Centre, Stanford Hall.

PARTICIPANTS

Two hundred eighty-three UK military personnel from the Royal Navy, Royal Airforce, Royal Marines, and British Army.

DESIGN

A retrospective analysis of data from the Ministry of Defence medical records database.

MAIN MEASURES

Sixteen-item Rivermead Post Concussion Symptoms Questionnaire, Generalized Anxiety Disorder 7-item scale, Patient Health Questionnaire-9, The Dizziness Handicap Inventory.

RESULTS

Injuries from sports or falls were the most common mechanism of mTBI, accounting for 23%, respectively. Chi-square analysis indicated that individuals with dizziness and postconcussion symptoms (PCS) had greater severity of PCS, depression, and anxiety than those with PCS alone. Mediation analysis showed dizziness directly and independently influenced the severity of PCS, despite the indirect effects of mediating depression and anxiety symptoms.

CONCLUSION

Comorbid dizziness and PCS were predictive of poorer mental health compared with PCS alone. In addition, dizziness directly influenced the severity of PCS irrespective of the indirect effects of mental health symptoms. These observations suggest that treating dizziness with vestibular rehabilitation may improve PCS and mental health.

An insight into crosstalk among multiple signalling pathways contributing to the pathophysiology of PTSD and depressive disorders

Post-traumatic stress disorder (PTSD) and depressive disorders represent two significant mental health challenges with substantial global prevalence. These are debilitating conditions characterized by persistent, often comorbid, symptoms that severely impact an individual's quality of life. Both PTSD and depressive disorders are often precipitated by exposure to traumatic events or chronic stress. The profound impact of PTSD and depressive disorders on individuals and society necessitates a comprehensive exploration of their shared and distinct pathophysiological features. Although the activation of the stress system is essential for maintaining homeostasis, the ability to recover from it after diminishing the threat stimulus is also equally important. However, little is known about the main reasons for individuals' differential susceptibility to external stressful stimuli. The solution to this question can be found by delving into the interplay of stress with the cognitive and emotional processing of traumatic incidents at the molecular level. Evidence suggests that dysregulation in these signalling cascades may contribute to the persistence and severity of PTSD and depressive symptoms. The treatment strategies available for this disorder are antidepressants, which have shown good efficiency in normalizing symptom severity; however, their efficacy is limited in most individuals. This calls for the exploration and development of innovative medications to address the treatment of PTSD. This review delves into the intricate crosstalk among multiple signalling pathways implicated in the development and manifestation of these mental health conditions. By unravelling the complexities of crosstalk among multiple signalling pathways, this review aims to contribute to the broader knowledge base, providing insights that could inform the development of targeted interventions for individuals grappling with the challenges of PTSD and depressive disorders.

Effects of Mild Closed-Head Injury and Subanesthetic Ketamine Infusion on Microglia, Axonal Injury, and Synaptic Density in Sprague-Dawley Rats

Mild traumatic brain injury (mTBI) affects millions of people in the U.S. Approximately 20-30% of those individuals develop adverse symptoms lasting at least 3 months. In a rat mTBI study, the closed-head impact model of engineered rotational acceleration (CHIMERA) produced significant axonal injury in the optic tract (OT), indicating white-matter damage. Because retinal ganglion cells project to the lateral geniculate nucleus (LGN) in the thalamus through the OT, we hypothesized that synaptic density may be reduced in the LGN of rats following CHIMERA injury. A modified SEQUIN (synaptic evaluation and quantification by imaging nanostructure) method, combined with immunofluorescent double-labeling of pre-synaptic (synapsin) and post-synaptic (PSD-95) markers, was used to quantify synaptic density in the LGN. Microglial activation at the CHIMERA injury site was determined using Iba-1 immunohistochemistry. Additionally, the effects of ketamine, a potential neuroprotective drug, were evaluated in CHIMERA-induced mTBI. A single-session repetitive (ssr-) CHIMERA (3 impacts, 1.5 joule/impact) produced mild effects on microglial activation at the injury site, which was significantly enhanced by post-injury intravenous ketamine (10 mg/kg) infusion. However, ssr-CHIMERA did not alter synaptic density in the LGN, although ketamine produced a trend of reduction in synaptic density at post-injury day 4. Further research is necessary to characterize the effects of ssr-CHIMERA and subanesthetic doses of intravenous ketamine on different brain regions and multiple time points post-injury. The current study demonstrates the utility of the ssr-CHIMERA as a rodent model of mTBI, which researchers can use to identify biological mechanisms of mTBI and to develop improved treatment strategies for individuals suffering from head trauma.

Effectiveness of rTMS and tDCS treatment for chronic TBI symptoms: A systematic review and meta-analysis

INTRODUCTION

Traumatic brain injury (TBI) is a major cause of long-term disability with conventional treatments frequently falling short to restore a good quality-of-life. Non-invasive brain stimulation (NIBS) techniques have shown potential as therapeutic options for neuropsychiatric conditions, including TBI sequelae. This study aims at providing a systematic review and meta-analysis on the effectiveness of repetitive transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) on post-TBI symptoms.

METHODS

Fifteen randomized controlled trials (RCTs) on adult TBI patients that examined the effects of multiple treatment sessions of NIBS techniques were selected from five databases. Symptoms were clustered into four categories: depression, anxiety, headache and cognitive dysfunctions. Meta-analysis was performed using correlated and hierarchical effects models.

RESULTS

There were only few and heterogeneous studies with generally small sample sizes. Most studies targeted the dorsolateral prefrontal cortex (dlPFC). Overall, the effects of NIBS were small. However, there was a significant effect for overall symptoms (0.404, p = 0.031). Moreover, subgroup analyses revealed significant overall effects for anxiety (0.195, p = 0.020) and headache (0.354, p = 0.040).

CONCLUSIONS

To date, there is limited evidence supporting the effectiveness of NIBS concerning treatment for TBI sequelae. The observed effect sizes were modest, suggesting subtle improvements rather than drastic changes. While NIBS techniques remain promising for treating neuropsychiatric conditions, larger RCT studies with longer follow-ups, optimized stimulation parameters and standardized methodology are required to establish their efficacy in addressing TBI sequelae.

Regional associations of white matter integrity and neurological, post-traumatic stress disorder and autonomic symptoms in Veterans with and without history of loss of consciousness in mild TBI

Background

Posttraumatic stress disorder (PTSD) and mild traumatic brain injury (mTBI) share overlapping symptom presentations and are highly comorbid conditions among Veteran populations. Despite elevated presentations of PTSD after mTBI, mechanisms linking the two are unclear, although both have been associated with alterations in white matter and disruptions in autonomic regulation. The present study aimed to determine if there is regional variability in white matter correlates of symptom severity and autonomic functioning in a mixed sample of Veterans with and without PTSD and/or mTBI (N = 77).

Methods

Diffusion-weighted images were processed to extract fractional anisotropy (FA) values for major white matter structures. The PTSD Checklist-Military version (PCL-M) and Neurobehavioral Symptom Inventory (NSI) were used to determine symptom domains within PTSD and mTBI. Autonomic function was assessed using continuous blood pressure and respiratory sinus arrythmia during a static, standing angle positional test. Mixed-effect models were used to assess the regional specificity of associations between symptom severity and white matter, with FA, global symptom severity (score), and white matter tract (tract) as predictors. Additional interaction terms of symptom domain (i.e., NSI and PCL-M subscales) and loss of consciousness (LoC) were added to evaluate potential moderating effects. A parallel analysis was conducted to explore concordance with autonomic functioning.

Results

Results from the two-way Score × Tract interaction suggested that global symptom severity was associated with FA in the cingulum angular bundle (positive) and uncinate fasciculus (negative) only, without variability by symptom domain. We also found regional specificity in the relationship between FA and autonomic function, such that FA was positively associated with autonomic function in all tracts except the cingulum angular bundle. History of LoC moderated the association for both global symptom severity and autonomic function.

Conclusions

Our findings are consistent with previous literature suggesting that there is significant overlap in the symptom presentation in TBI and PTSD, and white matter variability associated with LoC in mTBI may be associated with increased PTSD-spectra symptoms. Further research on treatment response in patients with both mTBI history and PTSD incorporating imaging and autonomic assessment may be valuable in understanding the role of brain injury in treatment outcomes and inform treatment design.

Potential oxidative stress related targets of mitochondria-focused therapy of PTSD

Post-traumatic stress disorder (PTSD) remains a highly prevalent, under-diagnosed, and under-treated psychiatric disorder that often deteriorates over time, and is highly comorbid with major depressive disorder, suicidality, and substance use disorder. Several biomarkers have been proposed but have yet to be implemented into clinical practice. Treatments, including selective serotonin reuptake inhibitors, are efficacious in only a small number of patients, which underscores the need to develop novel, efficient treatments. Mitochondrial dysfunction resulting from chronic oxidative stress has been linked with both altered neurotransmitter signaling and the inflammatory response. Hereinafter, we discuss mechanisms by which mitochondrial dysfunction may contribute to the development of PTSD symptoms, and how these may even increase PTSD susceptibility. We also highlight possible therapeutic targets to reduce oxidative stress to prevent or treat PTSD symptoms.

The impact of early life stress and schizophrenia on motor and cognitive functioning: an experimental study

Background

Early life stress (ELS) and parental psychopathology, such as schizophrenia (SZ), have been associated with altered neurobiological and behavioral outcomes later in life. Previous studies have investigated the effects of ELS and parental SZ on various aspects of behavior, however, we have studied the combined effects of these stressors and how they interact, as individuals in real-life situations may experience multiple stressors simultaneously.

Objective

The aim of this study was to investigate the impact of ELS and schizophrenia on locomotor activity, anxiety-like behavior, exploratory tendencies, and spatial memory in Sprague Dawley (SD) rats.

Methods

Male and female SD pups were randomly assigned to eight groups: control, ELS, schizophrenia, and ELS + schizophrenia. ELS was induced by prenatal stress (maternal stress) and maternal separation (MS) during the first 2 weeks of life, while SZ was induced by subcutaneous administration of ketamine. Behavioral tests included an open field test (OFT) for motor abilities and a Morris water maze (MWM) for cognitive abilities. ANOVA and post hoc Tukey tests were utilized to analyze the data.

Results

Our results show that ELS and parental psychopathology had enduring effects on SZ symptoms, particularly psychomotor retardation (p < 0.05). The OFT revealed increased anxiety-like behavior in the ELS group (p = 0.023) and the parental psychopathology group (p = 0.017) compared to controls. The combined ELS and parental psychopathology group exhibited the highest anxiety-like behavior (p = 0.006). The MWM analysis indicated impaired spatial memory in the ELS group (p = 0.012) and the combined ELS and parental psychopathology group (p = 0.003) compared to controls. Significantly, the exposure to ELS resulted in a decrease in the population of glial fibrillary acidic protein-positive (GFAP+) astrocytes. However, this effect was reversed by positive parental mental health.

Conclusion

Our findings highlight the interactive effects of ELS and parental psychopathology on anxiety-like behavior and spatial memory in rats. ELS was linked to increased anxiety-like behavior, while SZ was associated with anhedonia-like behavior. Positive parenting augments neuroplasticity, synaptic function, and overall cognitive capacities.

Neurologic Injury-Related Predisposing Factors of Post-Traumatic Stress Disorder: A Critical Examination

The present review aimed to identify the means through which neurologic injury can predispose individuals to Post-Traumatic Stress Disorder (PTSD). In recent years, comprehensive studies have helped to clarify which structures in the central nervous system can lead to distinct PTSD symptoms-namely, dissociative reactions or flashbacks-when damaged. Our review narrowed its focus to three common neurologic injuries, traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), and stroke. We found that in each of the three cases, individuals may be at an increased risk of developing PTSD symptoms. Beyond discussing the potential mechanisms by which neurotrauma may lead to PTSD, we summarized our current understanding of the pathophysiology of the disorder and discussed predicted associations between the limbic system and PTSD. In particular, the effect of noradrenergic neuromodulatory signaling on the hypothalamic pituitary adrenal (HPA) axis as it pertains to fear memory recall needs to be further explored to better understand its effects on limbic structures in PTSD patients. At present, altered limbic activity can be found in both neurotrauma and PTSD patients, suggesting a potential causative link. Particularly, changes in the function of the limbic system may be associated with characteristic symptoms of PTSD such as intrusive memories and acute psychological distress. Despite evidence demonstrating the correlation between neurotrauma and PTSD, a lack of PTSD prognosis exists in TBI, SAH, and stroke patients who could benefit from early treatment. It should be noted that PTSD symptoms often compound with pre-existing issues, further deteriorating health outcomes for these patients. It is ultimately our goal to clarify the relationship between neurotrauma and PTSD so that earlier diagnoses and appropriate treatment are observed in clinic.

Bedside to bench: the outlook for psychedelic research

There has recently been a resurgence of interest in psychedelic compounds based on studies demonstrating their potential therapeutic applications in treating post-traumatic stress disorder, substance abuse disorders, and treatment-resistant depression. Despite promising efficacy observed in some clinical trials, the full range of biological effects and mechanism(s) of action of these compounds have yet to be fully established. Indeed, most studies to date have focused on assessing the psychological mechanisms of psychedelics, often neglecting the non-psychological modes of action. However, it is important to understand that psychedelics may mediate their therapeutic effects through multi-faceted mechanisms, such as the modulation of brain network activity, neuronal plasticity, neuroendocrine function, glial cell regulation, epigenetic processes, and the gut-brain axis. This review provides a framework supporting the implementation of a multi-faceted approach, incorporating in silico, in vitro and in vivo modeling, to aid in the comprehensive understanding of the physiological effects of psychedelics and their potential for clinical application beyond the treatment of psychiatric disorders. We also provide an overview of the literature supporting the potential utility of psychedelics for the treatment of brain injury (e.g., stroke and traumatic brain injury), neurodegenerative diseases (e.g., Parkinson's and Alzheimer's diseases), and gut-brain axis dysfunction associated with psychiatric disorders (e.g., generalized anxiety disorder and major depressive disorder). To move the field forward, we outline advantageous experimental frameworks to explore these and other novel applications for psychedelics.

An Understated Comorbidity: The Impact of Homelessness on Traumatic Brain Injury

Traumatic brain injury (TBI), a neurovascular injury caused by external force, is a common diagnosis among veterans and those experiencing homelessness (HL). There is a significant overlap in the veteran and homeless population, possibly accounting for the two to seven times greater incidence of TBI among those experiencing HL than the general population. Despite these statistics, individuals experiencing HL are often underdiagnosed and ineffectively treated for TBI. We introduced a novel model of HL. Over 5 weeks, adult Sprague-Dawley rats were randomly assigned to one of the following conditions: TBI only, HL only, TBI + HL, or control (n = 9 per group). To emulate HL, animals (2 animals per cage) were exposed to soiled beddings for 5 weeks. Subsequently, animals were introduced to TBI by using the moderate controlled cortical impact model, then underwent 4 consecutive days of behavioral testing (beam walk (BW), elevated body swing test (EBST), forelimb akinesia (FA), paw grasp (PG), Rotorod, and elevated T-maze). Nissl staining was performed to determine the peri-impact cell survival and the integrity of corpus callosum area. Motor function was significantly impaired by TBI, regardless of housing (beam walk or BW 85.0%, forelimb akinesia or FA 104.7%, and paw grasp or PG 100% greater deficit compared to control). Deficits were worsened by HL in TBI rats (BW 93.3%, FA 40.5%, and PG 50% greater deficit). Two-way ANOVA revealed BW (F(4, 160) = 31.69, p < 0.0001), FA (F(4, 160) = 13.71, p < 0.0001), PG (F(4, 160) = 3.873, p = 0.005), Rotorod (F(4, 160), p = 1.116), and EBST (F(4, 160) = 6.929, p < 0.0001) showed significant differences between groups. The Rotorod and EBST tests showed TBI-induced functional deficits when analyzed by day, but these deficits were not exacerbated by HL. TBI only and TBI + HL rats exhibited typical cortical impact damage (F(3,95) = 51.75, p < 0.0001) and peri-impact cell loss compared to control group (F(3,238) = 47.34, p < 0.0001). Most notably, TBI + HL rats showed significant alterations in WM area measured via the corpus callosum (F(3, 95) = 3.764, p = 0.0133). Worsened behavioral outcomes displayed by TBI + HL rats compared to TBI alone suggest HL contributes to TBI functional deficits. While an intact white matter, such as the corpus callosum, may lessen the consequent functional deficits associated with TBI by enhancing hemispheric communications, there are likely alternative cellular and molecular pathways mitigating TBI-associated inflammatory or oxidative stress responses. Here, we showed that the environmental condition of the patient, i.e., HL, participates in white matter integrity and behavioral outcomes, suggesting its key role in the disease diagnosis to aptly treat TBI patients.

Levels of Arachidonic Acid-Derived Oxylipins and Anandamide Are Elevated Among Military APOE ɛ4 Carriers With a History of Mild Traumatic Brain Injury and Post-Traumatic Stress Disorder Symptoms

Currently approved blood biomarkers detect intracranial lesions in adult patients with mild to moderate traumatic brain injury (TBI) acutely post-injury. However, blood biomarkers are still needed to help with a differential diagnosis of mild TBI (mTBI) and post-traumatic stress disorder (PTSD) at chronic post-injury time points. Owing to the association between phospholipid (PL) dysfunction and chronic consequences of TBI, we hypothesized that examining bioactive PL metabolites (oxylipins and ethanolamides) would help identify long-term lipid changes associated with mTBI and PTSD. Lipid extracts of plasma from active-duty soldiers deployed to the Iraq/Afghanistan wars (control = 52, mTBI = 21, PTSD = 34, and TBI + PTSD = 13) were subjected to liquid chromatography/mass spectrometry analysis to examine oxylipins and ethanolamides. Linear regression analyses followed by post hoc comparisons were performed to assess the association of these lipids with diagnostic classifications. Significant differences were found in oxylipins derived from arachidonic acid (AA) between controls and mTBI, PTSD, and mTBI + PTSD groups. Levels of AA-derived oxylipins through the cytochrome P450 pathways and anandamide were significantly elevated among mTBI + PTSD patients who were carriers of the apolipoprotein E E4 allele. These studies demonstrate that AA-derived oxylipins and anandamide may be unique blood biomarkers of PTSD and mTBI + PTSD. Further, these AA metabolites may be indicative of an underlying inflammatory process that warrants further investigation. Future validation studies in larger cohorts are required to determine a potential application of this approach in providing a differential diagnosis of mTBI and PTSD in a clinical setting.

Open-label study of consecutive ibogaine and 5-MeO-DMT assisted-therapy for trauma-exposed male Special Operations Forces Veterans: prospective data from a clinical program in Mexico

Background: Research in psychedelic medicine has focused primarily on civilian populations. Further study is needed to understand whether these treatments are effective for Veteran populations.Objectives: Here, we examine the effectiveness of psychedelic-assisted therapy among trauma-exposed Special Operations Forces Veterans (SOFV) seeking treatment for cognitive and mental health problems in Mexico.Methods: Data were collected from an ibogaine and 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) clinical treatment program for SOFV with a history of trauma exposure. This clinical program collects prospective clinical program evaluation data, such as background characteristics, symptom severity, functioning (e.g., satisfaction with life, posttraumatic stress disorder symptoms, depression symptoms, anxiety symptoms, sleep disturbance, psychological flexibility, disability in functioning, cognitive functioning, neurobehavioral symptoms, anger, suicidal ideation), and substance persisting/enduring effects through online surveys at four timepoints (baseline/pre-treatment, one-, three-, and six-months after treatment).Results: The majority of the sample (n = 86; Mean Age = 42.88, SD = 7.88) were Caucasian (87.2%), non-Hispanic (89.5%), and males (100%). There were significant and large improvements in self-reported PTSD symptoms (p < .001, d = .414), depression (p < .001, d = .275), anxiety (p < .001, d = .276), insomnia severity (p < .001, d = .351), and post-concussive symptoms (p < .001, d = .389) as well as self-reported satisfaction with life (p < .001, d = .371), psychological flexibility (p < .001, d = .313) and cognitive functioning (p < .001, d = .265) from baseline to one-month follow-up.Conclusions: Data suggest combined ibogaine and 5-MeO-DMT assisted therapy has potential to provide rapid and robust changes in mental health functioning with a signal of durable therapeutic effects up to 6-months. Future research in controlled settings is warranted.

The Intestinal Microbiome after Traumatic Injury

The intestinal microbiome plays a critical role in host immune function and homeostasis. Patients suffering from-as well as models representing-multiple traumatic injuries, isolated organ system trauma, and various severities of traumatic injury have been studied as an area of interest in the dysregulation of immune function and systemic inflammation which occur after trauma. These studies also demonstrate changes in gut microbiome diversity and even microbial composition, with a transition to a pathobiome state. In addition, sex has been identified as a biological variable influencing alterations in the microbiome after trauma. Therapeutics such as fecal transplantation have been utilized to ameliorate not only these microbiome changes but may also play a role in recovery postinjury. This review summarizes the alterations in the gut microbiome that occur postinjury, either in isolated injury or multiple injuries, along with proposed mechanisms for these changes and future directions for the field.

Self-Reported Symptoms in U.S. Marines Following Blast- and Impact-Related Concussion

INTRODUCTION

Recent research on traumatic brain injury (TBI) has suggested that the mechanism of injury (i.e., whether the TBI was caused by high-level blast [HLB] vs. direct physical impact to the head) may be an important factor in injury severity, symptomology, and recovery because of differences in physiological effects of each type of injury on the brain. However, differences in self-reported symptomology resulting from HLB- vs. impact-related TBIs have not been thoroughly examined. This study tested the hypothesis that HLB- and impact-related concussions result in different self-reported symptoms in an enlisted Marine Corps population.

MATERIALS AND METHODS

All records of 2008 and 2012 Post-Deployment Health Assessment (PDHA) forms completed by enlisted active duty Marines between January 2008 and January 2017 were examined for self-reported concussion, mechanism of injury, and self-reported symptoms experienced during deployment. Concussion events were categorized as either blast- or impact-related; individual symptoms were categorized as neurological, musculoskeletal, or immunological. A series of logistic regressions were performed to examine associations between self-reported symptoms experienced by healthy controls and Marines who endorsed (1) any concussion (mTBI), (2) a probable blast-related concussion (mbTBI), and (3) a probable impact-related concussion (miTBI); analyses were also stratified by PTSD. To determine if there were significant differences between odds ratios (ORs) for mbTBIs vs. miTBIs, 95% CIs were examined for overlap.

RESULTS

Marines with a probable concussion, regardless of the mechanism of injury, were significantly more likely to report all symptoms (OR range: 1.7-19.3). Overall, mbTBIs, compared with miTBIs, resulted in higher odds of symptom reporting for eight symptoms on the 2008 PDHA (tinnitus, trouble hearing, headache, memory problems, dizziness, dim vision, trouble concentrating, and vomiting) and six symptoms on the 2012 PDHA (tinnitus, trouble hearing, headaches, memory problems, balance problems, and increased irritability), all of which were in the neurological symptom category. Conversely, odds of symptom reporting were higher for Marines experiencing miTBIs (vs. mbTBIs) for seven symptoms on the 2008 PDHA (skin diseases or rashes, chest pain, trouble breathing, persistent cough, red eyes, fever, and other) and one symptom on the 2012 PDHA (skin rash and/or lesion), all of which were in the immunological symptoms category. mbTBI (vs. miTBI) was consistently associated with greater odds of reporting tinnitus, trouble hearing, and memory problems, regardless of PTSD status.

CONCLUSIONS

These findings support recent research suggesting that the mechanism of injury may play an important role in symptom reporting and/or physiological changes to the brain after concussion. The results of this epidemiological investigation should be used to guide further research on the physiological effects of concussion, diagnostic criteria for neurological injuries, and treatment modalities for various concussion-related symptoms.

Executive function improvement in response to meta-cognitive training in chronic mTBI / PTSD

Objective

We tested Goal Management Training (GMT), which has been recommended as an executive training protocol that may improve the deficits in the complex tasks inherent in life role participation experienced by those with chronic mild traumatic brain injury and post-traumatic stress disease (mTBI/PTSD). We assessed, not only cognitive function, but also life role participation (quality of life).

Methods

We enrolled and treated 14 individuals and administered 10 GMT sessions in-person and provided the use of the Veterans Task Manager (VTM), a Smartphone App, which was designed to serve as a "practice-buddy" device to ensure translation of in-person learning to independent home and community practice of complex tasks. Pre-/post-treatment primary measure was the NIH Examiner, Unstructured Task. Secondary measures were as follows: Tower of London time to complete (cTOL), Community Reintegration of Service Members (CRIS) three subdomains [Extent of Participation; Limitations; Satisfaction of Life Role Participation (Satisfaction)]. We analyzed pre-post-treatment, t-test models to explore change, and generated descriptive statistics to inspect given individual patterns of change across measures.

Results

There was statistically significant improvement for the NIH EXAMINER Unstructured Task (p < .02; effect size = .67) and cTOL (p < .01; effect size = .52. There was a statistically significant improvement for two CRIS subdomains: Extent of Participation (p < .01; effect size = .75; Limitations (p < .05; effect size = .59). Individuals varied in their treatment response, across measures.

Conclusions and Clinical Significance

In Veterans with mTBI/PTSD in response to GMT and the VTM learning support buddy, there was significant improvement in executive cognition processes, sufficiently robust to produce significant improvement in community life role participation. The individual variations support need for precision neurorehabilitation. The positive results occurred in response to treatment advantages afforded by the content of the combined GMT and the employment of the VTM learning support buddy, with advantages including the following: manualized content of the GMT; incremental complex task difficulty; GMT structure and flexibility to incorporate individualized functional goals; and the VTM capability of ensuring translation of in-person instruction to home and community practice, solidifying newly learned executive cognitive processes. Study results support future study, including a potential randomized controlled trial, the manualized GMT and availability of the VTM to ensure future clinical deployment of treatment, as warranted.

Recent advances in the role of miRNAs in post-traumatic stress disorder and traumatic brain injury

Post-traumatic stress disorder (PTSD) is usually considered a psychiatric disorder upon emotional trauma. However, with the rising number of conflicts and traffic accidents around the world, the incidence of PTSD has skyrocketed along with traumatic brain injury (TBI), a complex neuropathological disease due to external physical force and is also the most common concurrent disease of PTSD. Recently, the overlap between PTSD and TBI is increasingly attracting attention, as it has the potential to stimulate the emergence of novel treatments for both conditions. Of note, treatments exploiting the microRNAs (miRNAs), a well-known class of small non-coding RNAs (ncRNAs), have rapidly gained momentum in many nervous system disorders, given the miRNAs' multitudinous and key regulatory role in various biological processes, including neural development and normal functioning of the nervous system. Currently, a wealth of studies has elucidated the similarities of PTSD and TBI in pathophysiology and symptoms; however, there is a dearth of discussion with respect to miRNAs in both PTSD and TBI. In this review, we summarize the recent available studies of miRNAs in PTSD and TBI and discuss and highlight promising miRNAs therapeutics for both conditions in the future.

Knockdown of adenosine A2A receptors in hippocampal neurons prevents post-TBI fear memory retrieval

The formation of fear memory is crucial in emotional disorders such as PTSD and anxiety. Traumatic brain injury (TBI) can cause emotional disorders with dysregulated fear memory formation; however, their cross-interaction remains unclear and hurdled the treatment against TBI-related emotional disorders. While adenosine A2A receptor(A2AR) contributes to the physiological regulation of fear memory, this study aimed to evaluate the A2AR role and possible mechanisms in post-TBI fear memory formation using a craniocerebral trauma model, genetically modified A2AR mutant mice, and pharmacological A2AR agonist CGS21680 and antagonist ZM241385. Our finding showed (i) TBI enhanced mice freezing levels (fear memory) at seven days post-TBI; (ii) The A2AR agonist CGS21680 enhanced the post-TBI freezing levels; conversely, the A2AR antagonist ZM241385 reduced mice freezing level; further (iii) Genetic knockdown of neuronal A2AR in the hippocampal CA1, CA3, and DG regions reduced post-TBI freezing levels, while A2AR knockout in DG region yielded the most reduction in fear memory; finally, (iv) AAV-CaMKII-Cre virus-mediated DG deletion of A2AR on excitatory neurons led to a significant decreased freezing levels post-TBI. These findings indicate that brain trauma increases fear memory retrieval post-TBI, and A2AR on DG excitatory neurons plays a crucial role in this process. Importantly, inhibition of A2AR attenuates fear memory enhancement, which provides a new strategy to prevent fear memory formation/enhancement after TBI.

Stress and traumatic brain injury: An inherent bi-directional relationship with temporal and synergistic complexities

Traumatic brain injury (TBI) and stress are prevalent worldwide and can both result in life-altering health problems. While stress often occurs in the absence of TBI, TBI inherently involves some element of stress. Furthermore, because there is pathophysiological overlap between stress and TBI, it is likely that stress influences TBI outcomes. However, there are temporal complexities in this relationship (e.g., when the stress occurs) that have been understudied despite their potential importance. This paper begins by introducing TBI and stress and highlighting some of their possible synergistic mechanisms including inflammation, excitotoxicity, oxidative stress, hypothalamic-pituitary-adrenal axis dysregulation, and autonomic nervous system dysfunction. We next describe different temporal scenarios involving TBI and stress and review the available literature on this topic. In doing so we find initial evidence that in some contexts stress is a highly influential factor in TBI pathophysiology and recovery, and vice versa. We also identify important knowledge gaps and suggest future research avenues that will increase our understanding of this inherent bidirectional relationship and could one day result in improved patient care.

Disturbances in fear extinction learning after mild traumatic brain injury in mice are accompanied by alterations in dendritic plasticity in the medial prefrontal cortex and basolateral nucleus of the amygdala

Mild traumatic brain injury (mTBI) and post-traumatic stress disorder (PTSD) have emerged as the signature injuries of the U.S. veterans who served in Iraq and Afghanistan, and frequently co-occur in both military and civilian and populations. To better understand how fear learning and underlying neural systems might be altered after mTBI we examined the acquisition of cued fear conditioning and its extinction along with brain morphology and dendritic plasticity in a mouse model of mTBI. To induce mTBI in adult male C57BL/6J mice, a lateral fluid percussive injury (LFP 1.7) was produced using a fluid pulse of 1.7 atmosphere force to the right parietal lobe. Behavior in LFP 1.7 mice was compared to behavior in mice from two separate control groups: mice subjected to craniotomy without LFP injury (Sham) and mice that did not undergo surgery (Unoperated). Following behavioral testing, neural endpoints (dendritic structural plasticity and neuronal volume) were assessed in the basolateral nucleus of the amygdala (BLA), which plays a critical sensory role in fear learning, and medial prefrontal cortex (mPFC), responsible for executive functions and inhibition of fear behaviors. No gross motor abnormalities or increased anxiety-like behaviors were observed in LFP or Sham mice after surgery compared to Unoperated mice. We found that all mice acquired fear behavior, assessed as conditioned freezing to auditory cue in a single session of 6 trials, and acquisition was similar across treatment groups. Using a linear mixed effects analysis, we showed that fear behavior decreased overall over 6 days of extinction training with no effect of treatment group across extinction days. However, a significant interaction was demonstrated between the treatment groups during within-session freezing behavior (5 trials per day) during extinction training. Specifically, freezing behavior increased across within-session extinction trials in LFP 1.7 mice, whereas freezing behavior in control groups did not change on extinction test days, reflecting a dissociation between within-trial and between-trial fear extinction. Additionally, LFP mice demonstrated bilateral increases in dendritic spine density in the BLA and decreases in dendritic complexity in the PFC. The translational implications are that individuals with TBI undergoing fear extinction therapy may demonstrate within-session aberrant learning that could be targeted for more effective treatment interventions.

White Matter Microstructure Is Associated with Serum Neuroactive Steroids and Psychological Functioning

Military service members are at increased risk for mental health issues, and comorbidity with mild traumatic brain injury (mTBI) is common. Largely overlapping symptoms between conditions suggest a shared pathophysiology. The present work investigates the associations among white matter microstructure, psychological functioning, and serum neuroactive steroids that are part of the stress-response system. Diffusion-weighted brain imaging was acquired from 163 participants (with and without military affiliation) and free-water-corrected fractional anisotropy (FAT) was extracted. Associations between serum neurosteroid levels of allopregnanolone (ALLO) and pregnenolone (PREGNE), psychological functioning, and whole-brain white matter microstructure were assessed using regression models. Moderation models tested the effect of mTBI and comorbid post-traumatic stress disorder (PTSD) and mTBI on these associations. ALLO is associated with whole-brain white matter FAT (β = 0.24, t = 3.05, p = 0.006). This association is significantly modulated by PTSD+mTBI comorbidity (β = 0.00, t = 2.50, p = 0.027), although an mTBI diagnosis alone did not significantly impact this association (p = 0.088). There was no significant association between PREGNE and FAT (p = 0.380). Importantly, lower FAT is associated with poor psychological functioning (β = -0.19, t = -2.35, p = 0.020). This study provides novel insight into a potential common pathophysiological mechanism of neurosteroid dysregulation underlying the high risk for mental health issues in military service members. Further, comorbidity of PTSD and mTBI may bring the compensatory effects of the brain's stress response to their limit. Future research is needed to investigate whether neurosteroid regulation may be a promising tool for restoring brain health and improving psychological functioning.

Epigenetic and epitranscriptomic regulation of axon regeneration

Effective axonal regeneration in the adult mammalian nervous system requires coordination of elevated intrinsic growth capacity and decreased responses to the inhibitory environment. Intrinsic regenerative capacity largely depends on the gene regulatory network and protein translation machinery. A failure to activate these pathways upon injury is underlying a lack of robust axon regeneration in the mature mammalian central nervous system. Epigenetics and epitranscriptomics are key regulatory mechanisms that shape gene expression and protein translation. Here, we provide an overview of different types of modifications on DNA, histones, and RNA, underpinning the regenerative competence of axons in the mature mammalian peripheral and central nervous systems. We highlight other non-neuronal cells and their epigenetic changes in determining the microenvironment for tissue repair and axon regeneration. We also address advancements of single-cell technology in charting transcriptomic and epigenetic landscapes that may further facilitate the mechanistic understanding of differential regenerative capacity in neuronal subtypes. Finally, as epigenetic and epitranscriptomic processes are commonly affected by brain injuries and psychiatric disorders, understanding their alterations upon brain injury would provide unprecedented mechanistic insights into etiology of injury-associated-psychiatric disorders and facilitate the development of therapeutic interventions to restore brain function.

Posttraumatic stress symptom severity predicts cognitive decline beyond the effect of Alzheimer's disease biomarkers in Veterans

Chronic stress is a risk factor for dementia but whether it explains unique variance in cognitive decline in older adults above Alzheimer's disease (AD) biomarkers is unknown. In a preclinical cohort of Vietnam Veterans, we examined the relationship between posttraumatic stress disorder (PTSD) symptom severity, AD biomarkers of beta-amyloid (Aβ) and tau, and change in cognitive performance on two widely-used screeners, the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA). Analyses indicated that PTSD symptom severity was associated with a greater decline on the MMSE (p < 0.04) and MoCA (p < 0.024) after adjusting for biomarkers of AD, notably on the attention scale of the MoCA and the memory index of the MMSE. These analyses survived multiple comparison corrections. Taken together, PTSD symptom severity is associated with accelerated cognitive decline. Treating PTSD should be considered instrumental to maintaining cognitive function as adults age.

Efficacy of combined subanesthetic ketamine infusion and cervical sympathetic blockade as a symptomatic treatment of PTSD/TBI in a special forces patient with a 1-year follow-up: A case report

Co-occurrence of posttraumatic stress disorder (PTSD) and traumatic brain injury (TBI) symptoms are particularly prevalent in the special operations forces' community, along with other related conditions (e.g., endocrine dysregulation, sleep disorders, chronic pain). Ketamine infusion (KI) has been shown to increase neuroplasticity as well as memory improvement and cervical sympathetic block (CSB) has been shown to improve cognitive function, reduce sympathetic overactivity, and improve other symptoms of PTSD. We want to report the efficacious use of a single intervention consisting of bilateral CSB technique with subanesthetic KI X5 in a Special Operations Forces patient, diagnosed with PTSD with comorbid TBI, evaluated during treatment and at 1-year follow-up. We postulated KI and CSB would have a synergistic effect. Our patient received KI starting at 0.5 mg/kg, which was escalated daily. KI was combined with right-sided ultrasound-guided CSB (C6 and C4 levels). This was followed the next day by left-sided CSB and KI. Patient's PTSD symptoms were evaluated using the Posttraumatic Stress Disorder Checklist (PCL-5), Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), suicidal ideation and other related factors by Concise Health Risk Tracking Self Report (CHRTSR). All measures were assessed prior to treatment, during treatment, and 394 days after. KI combined with CSB showed immediate and prolonged benefits 394 days later regarding the symptoms of PTSD, anxiety, depression, suicidal ideation, and cognitive deterioration (patient report). KI combined with CSB can markedly reduce symptoms of PTSD, psychiatric comorbidities, and cognitive dysfunction.

Immune-metabolic mechanisms of post-traumatic stress disorder and atherosclerosis

The interaction of post-traumatic stress disorder (PTSD) and atherosclerosis (AS) increase the risk of mortality. Metabolism and immunity play important roles in the comorbidity associated with PTSD and AS. The adenosine monophosphate-activated protein kinase/mammalian target of rapamycin and phosphatidylinositol 3-kinase/Akt pathways are attractive research topics in the fields of metabolism, immunity, and autophagy. They may be effective intervention targets in the prevention and treatment of PTSD comorbidity with AS. Herein, we comprehensively review metabolic factors, including glutamate and lipid alterations, in PTSD comorbidity with AS and discuss the possible implications in the pathophysiology of the diseases.

Polygenic risk for mental disorders as predictors of posttraumatic stress disorder after mild traumatic brain injury

Many patients with mild traumatic brain injury (mTBI) are at risk for mental health problems such as posttraumatic stress disorder (PTSD). The objective of this study was to determine whether the polygenic risk for PTSD (or for related mental health disorders or traits including major depressive disorder [MDD] and neuroticism [NEU]) was associated with an increased likelihood of PTSD in the aftermath of mTBI. We used data from individuals of European ancestry with mTBI enrolled in TRACK-TBI (n = 714), a prospective longitudinal study of level 1 trauma center patients. One hundred and sixteen mTBI patients (16.3%) had probable PTSD (PCL-5 score ≥33) at 6 months post-injury. We used summary statistics from recent GWAS studies of PTSD, MDD, and NEU to generate polygenic risk scores (PRS) for individuals in our sample. A multivariable model that included age, sex, pre-injury history of mental disorder, and cause of injury explained 7% of the variance in the PTSD outcome; the addition of the PTSD-PRS (and five ancestral principal components) significantly increased the variance explained to 11%. The adjusted odds of PTSD in the uppermost PTSD-PRS quintile was nearly four times higher (aOR = 3.71, 95% CI 1.80-7.65) than in the lowest PTSD-PRS quintile. There was no evidence of a statistically significant interaction between PTSD-PRS and prior history of mental disorder, indicating that PTSD-PRS had similar predictive utility among those with and without pre-injury psychiatric illness. When added to the model, neither MDD-PRS nor NEU-PRS were significantly associated with the PTSD outcome. These findings show that the risk for PTSD in the context of mTBI is, in part, genetically influenced. They also raise the possibility that an individual's PRS could be clinically actionable if used-possibly with other non-genetic predictors-to signal the need for enhanced follow-up and early intervention; this precision medicine approach needs to be prospectively studied.

Posttraumatic Stress and Traumatic Brain Injury: Cognition, Behavior, and Neuroimaging Markers in Vietnam Veterans

BACKGROUND

Posttraumatic stress disorder (PTSD) and traumatic brain injury (TBI) are common in Veterans and linked to behavioral disturbances, increased risk of cognitive decline, and Alzheimer's disease.

OBJECTIVE

We studied the synergistic effects of PTSD and TBI on behavioral, cognitive, and neuroimaging measures in Vietnam war Veterans.

METHODS

Data were acquired at baseline and after about one-year from male Veterans categorized into: PTSD, TBI, PTSD+TBI, and Veteran controls without PTSD or TBI. We applied manual tractography to examine white matter microstructure of three fiber tracts: uncinate fasciculus (N = 91), cingulum (N = 87), and inferior longitudinal fasciculus (N = 95). ANCOVAs were used to compare Veterans' baseline behavioral and cognitive functioning (N = 285), white matter microstructure, amyloid-β (N = 230), and tau PET (N = 120). Additional ANCOVAs examined scores' differences from baseline to follow-up.

RESULTS

Veterans with PTSD and PTSD+TBI, but not Veterans with TBI only, exhibited poorer behavioral and cognitive functioning at baseline than controls. The groups did not differ in baseline white matter, amyloid-β, or tau, nor in behavioral and cognitive functioning, and tau accumulation change. Progression of white matter abnormalities of the uncinate fasciculus in Veterans with PTSD compared to controls was observed; analyses in TBI and PTSD+TBI were not run due to insufficient sample size.

CONCLUSIONS

PTSD and PTSD+TBI negatively affect behavioral and cognitive functioning, while TBI does not contribute independently. Whether progressive decline in uncinate fasciculus microstructure in Veterans with PTSD might account for cognitive decline should be further studied. Findings did not support an association between PTSD, TBI, and Alzheimer's disease pathology based on amyloid and tau PET.

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.

An examination of volumetric and cortical thickness correlates of posttraumatic nightmares in male active duty service members

Posttraumatic nightmares commonly occur after a traumatic experience. Despite significant deleterious effects on well-being and their role in posttraumatic stress disorder, posttraumatic nightmares remain understudied. The neuroanatomical structures of the amygdala, medial prefrontal cortex, hippocampus, and anterior cingulate cortex constitute the AMPHAC model (Levin and Nielsen, 2007), which is implicated in the neurophysiology of disturbing dreams of which posttraumatic nightmares is a part. However, this model has not been investigated using neuroimaging data. The present study sought to determine whether there are structural differences in the AMPHAC regions in relation to the occurrence of posttraumatic nightmares. Data were obtained from treatment-seeking male active duty service members (N = 351). Posttraumatic nightmares were not significantly related to gray matter volume, cortical surface area, or cortical thickness of any the AMPHAC regions when controlling for age and history of mild traumatic brain injury. Although the present analyses do not support an association between structural measures of AMPHAC regions and posttraumatic nightmares, we suggest that functional differences within and/or between these brain regions may be related to the occurrence of posttraumatic nightmares because functional and structural associations are distinct. Future research should examine whether functional differences may be associated with posttraumatic nightmares.

Association of day-of-injury plasma glial fibrillary acidic protein concentration and six-month posttraumatic stress disorder in patients with mild traumatic brain injury

Several proteins have proven useful as blood-based biomarkers to assist in evaluation and management of traumatic brain injury (TBI). The objective of this study was to determine whether two day-of-injury blood-based biomarkers are predictive of posttraumatic stress disorder (PTSD). We used data from 1143 individuals with mild TBI (mTBI; defined as admission Glasgow Coma Scale [GCS] score 13-15) enrolled in TRACK-TBI, a prospective longitudinal study of level 1 trauma center patients. Plasma glial fibrillary acidic protein (GFAP) and serum high sensitivity C-reactive protein (hsCRP) were measured from blood collected within 24 h of injury. Two hundred and twenty-seven (19.9% of) patients had probable PTSD (PCL-5 score ≥ 33) at 6 months post-injury. GFAP levels were positively associated (Spearman's rho = 0.35, p < 0.001) with duration of posttraumatic amnesia (PTA). There was an inverse association between PTSD and (log)GFAP (adjusted OR = 0.85, 95% CI 0.77-0.95 per log unit increase) levels, but no significant association with (log)hsCRP (adjusted OR = 1.11, 95% CI 0.98-1.25 per log unit increase) levels. Elevated day-of-injury plasma GFAP, a biomarker of glial reactivity, is associated with reduced risk of PTSD after mTBI. This finding merits replication and additional studies to determine a possible neurocognitive basis for this relationship.

The influence of sleep on fear extinction in trauma-related disorders

In Posttraumatic Stress Disorder (PTSD), fear and anxiety become dysregulated following psychologically traumatic events. Regulation of fear and anxiety involves both high-level cognitive processes such as cognitive reattribution and low-level, partially automatic memory processes such as fear extinction, safety learning and habituation. These latter processes are believed to be deficient in PTSD. While insomnia and nightmares are characteristic symptoms of existing PTSD, abundant recent evidence suggests that sleep disruption prior to and acute sleep disturbance following traumatic events both can predispose an individual to develop PTSD. Sleep promotes consolidation in multiple memory systems and is believed to also do so for low-level emotion-regulatory memory processes. Consequently sleep disruption may contribute to the etiology of PTSD by interfering with consolidation in low-level emotion-regulatory memory systems. During the first weeks following a traumatic event, when in the course of everyday life resilient individuals begin to acquire and consolidate these low-level emotion-regulatory memories, those who will develop PTSD symptoms may fail to do so. This deficit may, in part, result from alterations of sleep that interfere with their consolidation, such as REM fragmentation, that have also been found to presage later PTSD symptoms. Here, sleep disruption in PTSD as well as fear extinction, safety learning and habituation and their known alterations in PTSD are first briefly reviewed. Then neural processes that occur during the early post-trauma period that might impede low-level emotion regulatory processes through alterations of sleep quality and physiology will be considered. Lastly, recent neuroimaging evidence from a fear conditioning and extinction paradigm in patient groups and their controls will be considered along with one possible neural process that may contribute to a vulnerability to PTSD following trauma.

The impact of neurotoxicant exposures on posttraumatic stress disorder trajectories: The Ft. Devens Gulf War Veterans Cohort

Gulf War veterans (GWVs) were exposed to neurotoxicants, including sarin nerve gas, anti-nerve agent pills, pesticides, oil well fires, and fumes from unvented tent heaters, all of which have been associated with subsequent adverse health. Posttraumatic stress disorder (PTSD) symptoms have also been associated with GW deployment; however, associations between exposures and PTSD symptoms have not been investigated. We assessed PTSD symptom trajectories and associations with neurotoxicant exposures in Ft. Devens Cohort (FDC) veterans (N = 259) who endorsed trauma exposure during deployment and completed the PTSD Checklist at three follow-ups (1992-1993, 1997-1998, 2013-2017). Results indicate that among veterans with more severe initial PTSD symptoms, symptoms remained significantly higher across follow-ups, Bs = -1.489-1.028, whereas among those with low initial PTSD symptoms, symptom severity increased significantly over time, Bs = 1.043-10.304. Additionally, neurotoxicant exposure was associated with a significant increase in PTSD symptoms, Bs = -1.870-9.003. Significant interactions between time and exposures were observed for PTSD symptom clusters, suggesting that among participants with high initial PTSD symptom, unexposed veterans experienced symptom alleviation, whereas exposed veterans' PTSD symptoms remained high. In GWVs with low initial PTSD symptoms, both unexposed and exposed veterans experienced PTSD symptom exacerbations over time; however, this occurred at a faster rate among exposed veterans. These findings suggest that in the years following deployment, GWVs who were exposed to both traumatic events and neurotoxicants may experience more severe and chronic PTSD symptoms than those without neurotoxicant exposures.

Sleep-Wake and Arousal Dysfunctions in Post-Traumatic Stress Disorder:Role of Orexin Systems

Post-traumatic stress disorder (PTSD) is a trauma-related condition that produces distressing fear memory intrusions, avoidance behaviors, hyperarousal/startle, stress responses and insomnia. This review focuses on the importance of the orexin neural system as a novel mechanism related to the pathophysiology of PTSD. Orexinergic neurons originate in the lateral hypothalamus and project widely to key neurotransmitter system neurons, autonomic neurons, the hypothalamic-pituitaryadrenal (HPA) axis, and fear-related neural circuits. After trauma or stress, the basolateral amygdala (BLA) transmits sensory information to the central nucleus of the amygdala (CeA) and in turn to the hypothalamus and other subcortical and brainstem regions to promote fear and threat. Orexin receptors have a prominent role in this circuit as fear conditioned orexin receptor knockout mice show decreased fear expression while dual orexin receptor antagonists (DORAs) inhibit fear acquisition and expression. Orexin activation of an infralimbic-amygdala circuit impedes fear extinction while DORA treatments enhance it. Increased orexin signaling to the amygdalocortical- hippocampal circuit promotes avoidance behaviors. Orexin has an important role in activating sympathetic nervous system (SNS) activity and the HPA axis stress responses. Blockade of orexin receptors reduces fear-conditioned startle responses. In PTSD models, individuals demonstrate sleep disturbances such as increased sleep latency and more transitions to wakefulness. Increased orexin activity impairs sleep by promoting wakefulness and reducing total sleep time while DORA treatments enhance sleep onset and maintenance. The orexinergic neural system provides important mechanisms for understanding multiple PTSD behaviors and provides new medication targets to treat this often persistent and debilitating illness.

The role of IL-6 in TBI and PTSD, a potential therapeutic target?

This literature review focuses on the role of IL-6 in TBI or PTSD-induced neuroinflammation. While TBI and PTSD are widely prevalent, these diagnoses are particularly common amongst veterans. Given the role of IL-6 in neuroprotection acutely, compared to detrimental chronically, targeting this cytokine at specific time points may be beneficial in modulating neuroinflammation. Current treatments for TBI or PTSD are variably affective. By reviewing the role of IL-6 in these two diagnoses, future studies can focus on therapeutics to treat neuroinflammation and ultimately reduce the devastating impacts of neuroinflammation on cognition in PTSD and TBI.

Neurobehavioral Symptoms and Heart Rate Variability: Feasibility of Remote Collection Using Mobile Health Technology

OBJECTIVES

To determine the covariance of heart rate variability (HRV) and self-reported neurobehavioral symptoms after traumatic brain injury (TBI) collected using mobile health (mHealth) technology.

SETTING

Community.

PARTICIPANTS

Adults with lifetime history of TBI (n = 52) and adults with no history of brain injury (n = 12).

DESIGN

Two-week prospective ecological momentary assessment study.

MAIN MEASURES

Behavioral Assessment Screening Tool (BASTmHealth) subscales (Negative Affect, Fatigue, Executive Dysfunction, Substance Abuse, and Impulsivity) measured frequency of neurobehavioral symptoms via a RedCap link sent by text message. Resting HRV (root mean square of successive R-R interval differences) was measured for 5 minutes every morning upon waking using a commercially available heart rate monitor (Polar H10, paired with Elite HRV app).

RESULTS

Data for n = 48 (n = 38 with TBI; n = 10 without TBI) participants were included in covariance analyses, with average cross-correlation coefficients (0-day lag) varying greatly across participants. We found that the presence and direction of the relationship between HRV and neurobehavioral symptoms varied from person to person. Cross-correlation coefficients r ≤ -0.30, observed in 27.1% to 29.2% of participants for Negative Affect, Executive Dysfunction, and Fatigue, 22.9% of participants for Impulsivity, and only 10.4% of participants for Substance Abuse, supported our hypothesis that lower HRV would covary with more frequent symptoms. However, we also found 2.0% to 20.8% of participants had positive cross-correlations (r ≥ 0.30) across all subscales, indicating that higher HRV may sometimes correlate with more neurobehavioral symptoms, and 54.2% to 87.5% had no significant cross-correlations.

CONCLUSIONS

It is generally feasible for community-dwelling adults with and without TBI to use a commercially available wearable device to capture daily HRV measures and to complete a short, electronic self-reported neurobehavioral symptom measure for a 2-week period. The covariance of HRV and neurobehavioral symptoms over time suggests that HRV could be used as a relevant physiological biomarker of neurobehavioral symptoms, though how it would be interpreted and used in practice would vary on a person-by-person and symptom domain basis and requires further study.

Detection of Chronic Blast-Related Mild Traumatic Brain Injury with Diffusion Tensor Imaging and Support Vector Machines

Blast-related mild traumatic brain injury (bmTBI) often leads to long-term sequalae, but diagnostic approaches are lacking due to insufficient knowledge about the predominant pathophysiology. This study aimed to build a diagnostic model for future verification by applying machine-learning based support vector machine (SVM) modeling to diffusion tensor imaging (DTI) datasets to elucidate white-matter features that distinguish bmTBI from healthy controls (HC). Twenty subacute/chronic bmTBI and 19 HC combat-deployed personnel underwent DTI. Clinically relevant features for modeling were selected using tract-based analyses that identified group differences throughout white-matter tracts in five DTI metrics to elucidate the pathogenesis of injury. These features were then analyzed using SVM modeling with cross validation. Tract-based analyses revealed abnormally decreased radial diffusivity (RD), increased fractional anisotropy (FA) and axial/radial diffusivity ratio (AD/RD) in the bmTBI group, mostly in anterior tracts (29 features). SVM models showed that FA of the anterior/superior corona radiata and AD/RD of the corpus callosum and anterior limbs of the internal capsule (5 features) best distinguished bmTBI from HCs with 89% accuracy. This is the first application of SVM to identify prominent features of bmTBI solely based on DTI metrics in well-defined tracts, which if successfully validated could promote targeted treatment interventions.

Decoding health status transitions of over 200 000 patients with traumatic brain injury from preceding injury to the injury event

For centuries, the study of traumatic brain injury (TBI) has been centred on historical observation and analyses of personal, social, and environmental processes, which have been examined separately. Today, computation implementation and vast patient data repositories can enable a concurrent analysis of personal, social, and environmental processes, providing insight into changes in health status transitions over time. We applied computational and data visualization techniques to categorize decade-long health records of 235,003 patients with TBI in Canada, from preceding injury to the injury event itself. Our results highlighted that health status transition patterns in TBI emerged along with the projection of comorbidity where many disorders, social and environmental adversities preceding injury are reflected in external causes of injury and injury severity. The strongest associations between health status preceding TBI and health status at the injury event were between multiple body system pathology and advanced age-related brain pathology networks. The interwoven aspects of health status on a time continuum can influence post-injury trajectories and should be considered in TBI risk analysis to improve prevention, diagnosis, and care.

A Scoping Review of Cognitive Assessment in Adults With Acute Traumatic Brain Injury

PURPOSE

The purpose of this study was to describe and synthesize the current research regarding the prevailing cognitive domains impacted by acute traumatic brain injury (TBI) in adults. Standardized and nonstandardized assessments of cognitive function and comorbidities influencing cognitive function during the initial stages of recovery are presented to help guide clinical assessment.

METHOD

A scoping review, guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses framework, was used to explore four electronic databases. Searches identified peer-reviewed empirical literature addressing aspects of cognitive domains impacted after TBI, cognitive assessment, and comorbidities impacting assessment in adults after acute TBI.

RESULTS

A total of 1,072 records were identified and reduced to 75 studies based on inclusion criteria. The cognitive domains most impacted in acute TBI were memory and executive function. The Glasgow Coma Scale (GCS) was the most frequently used tool to assess cognitive abilities, despite it being a measurement of consciousness, not of cognition. Psychological changes were the most commonly noted comorbidity impacting cognitive assessment.

CONCLUSIONS

Assessment of cognition after acute TBI requires a multifaceted approach that considers the typical profile of cognitive impairment, as well as patient-specific factors influencing cognitive abilities following initial brain injury. The present results support the generally held view that memory and executive function deficits are common cognitive difficulties associated with acute TBI in adults. The GCS remains the most widely used tool to assess function, though numerous tools are available that specifically address cognitive domains. Acute medical comorbidities common within this stage of injury are highlighted, as well as gaps of clinical knowledge that remain.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.18372086.

Neuroimaging Biomarkers of New-Onset Psychiatric Disorders Following Traumatic Brain Injury

Traumatic brain injury (TBI) has traditionally been associated with cognitive and behavioral changes during both the acute and chronic phases of injury. Because of its noninvasive nature, neuroimaging has the potential to provide unique information on underlying macroscopic and microscopic biological mechanisms that may serve as causative agents for these neuropsychiatric sequelae. This broad scoping review identifies at least 4 common macroscopic pathways that exist between TBI and new-onset psychiatric disorders, as well as several examples of how neuroimaging is currently being utilized in clinical research. The review then critically examines the strengths and limitations of neuroimaging for elucidating TBI-related microscopic pathology, such as microstructural changes, neuroinflammation, proteinopathies, blood-brain barrier damage, and disruptions in cellular signaling. A summary is then provided for how neuroimaging is currently being used to investigate TBI-related pathology in new-onset neurocognitive disorders, depression, and posttraumatic stress disorder. Identified gaps in the literature include a lack of prospective studies to definitively associate imaging findings with the development of new-onset psychiatric disorders, as well as antemortem imaging studies subsequently confirmed with postmortem correlates in the same study cohort. Although the spatial resolution and specificity of imaging biomarkers has greatly improved over the last 2 decades, we conclude that neuroimaging biomarkers do not yet exist for the definitive in vivo diagnosis of cellular pathology. This represents a necessary next step for further elucidating causal relationships between TBI and new-onset psychiatric disorders.

Emotion Dysregulation Following Trauma: Shared Neurocircuitry of Traumatic Brain Injury and Trauma-Related Psychiatric Disorders

The psychological trauma associated with events resulting in traumatic brain injury (TBI) is an important and frequently overlooked factor that may impede brain recovery and worsen mental health following TBI. Indeed, individuals with comorbid posttraumatic stress disorder (PTSD) and TBI have significantly poorer clinical outcomes than individuals with a sole diagnosis. Emotion dysregulation is a common factor leading to poor cognitive and affective outcomes following TBI. Here, we synthesize how acute postinjury molecular processes stemming from either physical or emotional trauma may adversely impact circuitry subserving emotion regulation and ultimately yield long-term system-level functional and structural changes that are common to TBI and PTSD. In the immediate aftermath of traumatic injury, glucocorticoids stimulate excess glutamatergic activity, particularly in prefrontal cortex-subcortical circuitry implicated in emotion regulation. In human neuroimaging work, assessing this same circuitry well after the acute injury, TBI and PTSD show similar impacts on prefrontal and subcortical connectivity and activation. These neural profiles indicate that emotion regulation may be a useful target for treatment and early intervention to prevent the adverse sequelae of TBI. Ultimately, the success of future TBI and PTSD early interventions depends on the fields' ability to address both the physical and emotional impact of physical injury.

Role of Inflammation in Traumatic Brain Injury-Associated Risk for Neuropsychiatric Disorders: State of the Evidence and Where Do We Go From Here

In the past decade, there has been an increasing awareness that traumatic brain injury (TBI) and concussion substantially increase the risk for developing psychiatric disorders. Even mild TBI increases the risk for depression and anxiety disorders such as posttraumatic stress disorder by two- to threefold, predisposing patients to further functional impairment. This strong epidemiological link supports examination of potential mechanisms driving neuropsychiatric symptom development after TBI. One potential mechanism for increased neuropsychiatric symptoms after TBI is via inflammatory processes, as central nervous system inflammation can last years after initial injury. There is emerging preliminary evidence that TBI patients with posttraumatic stress disorder or depression exhibit increased central and peripheral inflammatory markers compared with TBI patients without these comorbidities. Growing evidence has demonstrated that immune signaling in animals plays an integral role in depressive- and anxiety-like behaviors after severe stress or brain injury. In this review, we will 1) discuss current evidence for chronic inflammation after TBI in the development of neuropsychiatric symptoms, 2) highlight potential microglial activation and cytokine signaling contributions, and 3) discuss potential promise and pitfalls for immune-targeted interventions and biomarker strategies to identify and treat TBI patients with immune-related neuropsychiatric symptoms.

A review of the pathology and treatment of TBI and PTSD

This literature review focuses on the underlying pathophysiology of TBI and PTSD symptoms, while also examining the plethora of stem cell treatment options to ameliorate these neuronal and functional changes. As more veterans return suffering from TBI and/or PTSD, it is vital that researchers discover novel therapies to mitigate the detrimental symptoms of both diagnoses. A variety of stem cell treatments have been studied and offer hopeful options for TBI and PTSD recovery.

The prevalence, characteristics, and psychiatric correlates of traumatic brain injury in incarcerated individuals: an examination in two independent samples

PRIMARY OBJECTIVE

Identify the prevalence, characteristics, and psychological correlates of traumatic brain injury (TBI) among incarcerated individuals.

RESEARCH DESIGN

Three aims: (1) Determine the prevalence and characteristics of TBI in 1469 adults incarcerated in Wisconsin state prisons (1064 men, 405 women); (2) Characterize the relationship between mild TBI and mental illness in a sub-sample of men and women; (3) Reproduce the findings from Aim 1 and Aim 2 in an independent sample of 1015 adults incarcerated in New Mexico state prisons (600 men, 415 women).

METHODS AND PROCEDURES

Standardized TBI assessment with structured clinical interviews and self-report questionnaires.

MAIN OUTCOMES AND RESULTS

Rates of TBI were approximately five times greater than the general population, with a substantially higher rate of TBI caused by assault. In the Wisconsin sample, mild TBI was associated with greater levels of post-traumatic stress disorder (PTSD) among women (but not among men). In the New Mexico sample, TBI of any severity was associated with greater levels of major depressive disorder (MDD) among women (but not among men).

CONCLUSIONS

This study thus provides novel data on TBI and its correlates among individuals incarcerated in state prisons, and highlights a specific treatment need within the prison population.