Combat exposure, posttraumatic stress disorder, and head injuries differentially relate to alterations in cortical thickness in military Veterans

Psychosocial experiences are associated with human brain mitochondrial biology

Psychosocial experiences affect brain health and aging trajectories, but the molecular pathways underlying these associations remain unclear. Normal brain function relies on energy transformation by mitochondria oxidative phosphorylation (OxPhos). Two main lines of evidence position mitochondria both as targets and drivers of psychosocial experiences. On the one hand, chronic stress exposure and mood states may alter multiple aspects of mitochondrial biology; on the other hand, functional variations in mitochondrial OxPhos capacity may alter social behavior, stress reactivity, and mood. But are psychosocial exposures and subjective experiences linked to mitochondrial biology in the human brain? By combining longitudinal antemortem assessments of psychosocial factors with postmortem brain (dorsolateral prefrontal cortex) proteomics in older adults, we find that higher well-being is linked to greater abundance of the mitochondrial OxPhos machinery, whereas higher negative mood is linked to lower OxPhos protein content. Combined, positive and negative psychosocial factors explained 18 to 25% of the variance in the abundance of OxPhos complex I, the primary biochemical entry point that energizes brain mitochondria. Moreover, interrogating mitochondrial psychobiological associations in specific neuronal and nonneuronal brain cells with single-nucleus RNA sequencing (RNA-seq) revealed strong cell-type-specific associations for positive psychosocial experiences and mitochondria in glia but opposite associations in neurons. As a result, these "mind-mitochondria" associations were masked in bulk RNA-seq, highlighting the likely underestimation of true psychobiological effect sizes in bulk brain tissues. Thus, self-reported psychosocial experiences are linked to human brain mitochondrial phenotypes.

Optimising Combat Readiness: Practical Strategies for Integrating Physiological and Psychological Resilience in Soldier Training

This narrative review examines the intricate psychophysiological interplay between cognitive functions and physical responses within military personnel engaged in combat. It elucidates the spectrum of responses elicited by symmetric and asymmetric warfare alongside specialised combat scenarios, including close-quarters and subterranean warfare. Central to this discourse is the emphasis on integrating training programs beyond physical conditioning to encompass psychological resilience and decision-making efficacy under duress. The exploration further ventures into applying advanced technologies such as virtual reality and wearable devices, highlighting their pivotal role in augmenting training outcomes and supporting soldier health. Through a detailed analysis of psychophysiological variations across different military branches of service, the narrative review advocates for bespoke training regimens and support frameworks tailored to address the unique exigencies of each service branch. Concluding observations stress the importance of evolving military training paradigms, advocating for adopting realistic, immersive training simulations that mirror the complexities of the contemporary battlefield. This synthesis aims to contribute to the ongoing discourse on optimising military training protocols and enhancing the operational readiness and well-being of armed forces personnel. This narrative review is essential for military psychologists, trainers, and policymakers, aiming to bridge the gap between theoretical knowledge and practical implementation in military training programs.

Analysis of Palliative Care Knowledge and Symptom Burden Among Female Veterans With Serious Illness: A Cross-Sectional Study

Background: The female Veteran population is rapidly growing, as is their use of Veterans Affairs (VA) medical centers (VAMCs). Additionally, 90% of female Veterans are under 65 years old, meaning healthcare providers at VAMCs must be ready to manage the complex serious illnesses that affect female Veterans as they age. These serious illnesses require proper medical management, which can include palliative care. However, little palliative care research includes female Veterans. Aims: The aims of this cross-sectional study were to examine palliative care knowledge and symptom burden among female Veterans' and examine factors associated a symptom burden scale. Methods: Consenting participants completed online questionnaires, including the Palliative Care Knowledge Scale (PaCKS), Condensed Memorial Symptom Assessment Scale (CMSAS), and demographics. Descriptive statistics characterized the sample, bivariate association were carried out with a Chi-square and t test. A generalized linear model explored associations between CMSAS and its subscales with sociodemographic, number of serious illnesses, and facility type (VAMC vs civilian facility). Results: 152 female Veterans completed the survey. PaCKS scores were consistent across our sample. Physical symptoms were rated higher for those receiving care at VAMCs compared to civilian facilities (P = .02) in the bivariate analysis. The factors associated with CMSAS were age, employment status and number of serious illnesses (all P < .05). Conclusions: Palliative care can assist female Veterans with serious illness. More research is needed to further explore variables associated with symptom burden among female Veterans such as age, employment status, and number of serious illnesses.

Basal forebrain cholinergic systems as circuits through which traumatic stress disrupts emotional memory regulation

Contextual and spatial systems facilitate changes in emotional memory regulation brought on by traumatic stress. Cholinergic basal forebrain (chBF) neurons provide input to contextual/spatial systems and although chBF neurons are important for emotional memory, it is unknown how they contribute to the traumatic stress effects on emotional memory. Clusters of chBF neurons that project to the prefrontal cortex (PFC) modulate fear conditioned suppression and passive avoidance, while clusters of chBF neurons that project to the hippocampus (Hipp) and PFC (i.e. cholinergic medial septum and diagonal bands of Broca (chMS/DBB neurons) are critical for fear extinction. Interestingly, neither Hipp nor PFC projecting chMS/DBB neurons are critical for fear extinction. The retrosplenial cortex (RSC) is a contextual/spatial memory system that receives input from chMS/DBB neurons, but whether this chMS/DBB-RSC circuit facilitates traumatic stress effects on emotional memory remain unexplored. Traumatic stress leads to neuroinflammation and the buildup of reactive oxygen species. These two molecular processes may converge to disrupt chBF circuits enhancing the impact of traumatic stress on emotional memory.

Examining the association between posttraumatic stress disorder and disruptions in cortical networks identified using data-driven methods

Posttraumatic stress disorder (PTSD) is associated with lower cortical thickness (CT) in prefrontal, cingulate, and insular cortices in diverse trauma-affected samples. However, some studies have failed to detect differences between PTSD patients and healthy controls or reported that PTSD is associated with greater CT. Using data-driven dimensionality reduction, we sought to conduct a well-powered study to identify vulnerable networks without regard to neuroanatomic boundaries. Moreover, this approach enabled us to avoid the excessive burden of multiple comparison correction that plagues vertex-wise methods. We derived structural covariance networks (SCNs) by applying non-negative matrix factorization (NMF) to CT data from 961 PTSD patients and 1124 trauma-exposed controls without PTSD. We used regression analyses to investigate associations between CT within SCNs and PTSD diagnosis (with and without accounting for the potential confounding effect of trauma type) and symptom severity in the full sample. We performed additional regression analyses in subsets of the data to examine associations between SCNs and comorbid depression, childhood trauma severity, and alcohol abuse. NMF identified 20 unbiased SCNs, which aligned closely with functionally defined brain networks. PTSD diagnosis was most strongly associated with diminished CT in SCNs that encompassed the bilateral superior frontal cortex, motor cortex, insular cortex, orbitofrontal cortex, medial occipital cortex, anterior cingulate cortex, and posterior cingulate cortex. CT in these networks was significantly negatively correlated with PTSD symptom severity. Collectively, these findings suggest that PTSD diagnosis is associated with widespread reductions in CT, particularly within prefrontal regulatory regions and broader emotion and sensory processing cortical regions.

Impact of alcohol use, combat exposure, and posttraumatic stress on verbal and visual working memory performance in post-9/11 veterans

OBJECTIVE

Posttraumatic stress disorder (PTSD) and alcohol use (AU) are highly prevalent and comorbid among post-9/11 U.S. military veterans. Both issues are associated with working memory (WM) deficits, but have rarely been studied concurrently in cognitive studies of post-9/11 veterans. They also have been measured inconsistently, with variable outcomes, in prior veteran studies despite their relevance to new intervention paradigms involving WM.

METHOD

The present study evaluated 52 post-9/11 veterans [predominantly male (94.2%); White (44.2%) or Black (36.5%); 50% being diagnosed with PTSD based on CAPS-5 results] with objectively verified valid neuropsychological test performance on measures of PTSD, AU, combat exposure, and verbal and visual WM.

RESULTS

PTSD was not associated with verbal or visual WM performances, whereas AU and combat exposure were significantly associated with poorer visual WM performances.

CONCLUSIONS

AU and prior combat exposure may influence visual WM performances in post-9/11 veterans, which is relevant to novel PTSD treatment paradigms. This sample was limited to mostly male and White or Black participants, and future studies should focus on sampling more heterogeneous groups of veterans with regard to sex and ethnicity. Improvements in specification/multimodal WM assessment are important for future research, as these may directly impact developing intervention efforts. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Supporting the Frontlines: A Scoping Review Addressing the Health Challenges of Military Personnel and Veterans

(1) Background: Military personnel and veterans meet unique health challenges that stem from the complex interplay of their service experiences, the nature of warfare, and their interactions with both military and civilian healthcare systems. This study aims to examine the myriad of injuries and medical conditions specific to this population, encompassing physical and psychological traumas. (2) Methods: A scoping review (systematic search and non-systematic review) was performed to evaluate the current landscape of military healthcare. (3) Results: A significant change in the injury profile over time is identified, linked to shifts in combat strategies and the integration of advanced technologies in warfare. Environmental exposures to diverse chemical or natural agents further complicate the health of service members. Additionally, the stressors they face, ranging from routine stress to traumatic experiences, lead to various mental health challenges. A major concern is the gap in healthcare accessibility and quality, worsened by challenges in the civilian healthcare system's capacity to address these unique needs and the military healthcare system's limitations. (4) Conclusions: This review underscores the need for holistic, integrated approaches to care, rigorous research, and targeted interventions to better serve the health needs of military personnel and veterans.

Neurobiological and genetic correlates of the dissociative subtype of posttraumatic stress disorder

Approximately 10%-30% of individuals with posttraumatic stress disorder (PTSD) exhibit a dissociative subtype of the condition defined by symptoms of depersonalization and derealization. This study examined the psychometric evidence for the dissociative subtype of PTSD in a sample of young, primarily male post-9/11-era Veterans (n = 374 at baseline and n = 163 at follow-up) and evaluated its biological correlates with respect to resting state functional connectivity (default mode network [DMN]; n = 275), brain morphology (hippocampal subfield volume and cortical thickness; n = 280), neurocognitive functioning (n = 337), and genetic variation (n = 193). Multivariate analyses of PTSD and dissociation items suggested a class structure was superior to dimensional and hybrid ones, with 7.5% of the sample comprising the dissociative class; this group showed stability over 1.5 years. Covarying for age, sex, and PTSD severity, linear regression models revealed that derealization/depersonalization severity was associated with: decreased DMN connectivity between bilateral posterior cingulate cortex and right isthmus (p = .015; adjusted-p [padj] = .097); increased bilateral whole hippocampal, hippocampal head, and molecular layer head volume (p = .010-.034; padj = .032-.053); worse self-monitoring (p = .018; padj = .079); and a candidate genetic variant (rs263232) in the adenylyl cyclase 8 gene (p = .026), previously associated with dissociation. Results converged on biological structures and systems implicated in sensory integration, the neural representation of spatial awareness, and stress-related spatial learning and memory, suggesting possible mechanisms underlying the dissociative subtype of PTSD. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Blast-Induced Neurotrauma Results in Spatially Distinct Gray Matter Alteration Alongside Hormonal Alteration: A Preliminary Investigation

Blast-induced neurotrauma (BINT) frequently occurs during military training and deployment and has been linked to long-term neuropsychological and neurocognitive changes, and changes in brain structure. As military personnel experience frequent exposures to stress, BINT may negatively influence stress coping abilities. This study aimed to determine the effects of BINT on gray matter volume and hormonal alteration. Participants were Canadian Armed Forces personnel and veterans with a history of BINT (n = 12), and first responder controls (n = 8), recruited due to their characteristic occupational stress professions. Whole saliva was collected via passive drool on the morning of testing and analyzed for testosterone (pg/mL), cortisol (μg/dL), and testosterone/cortisol (T/C) ratio. Voxel-based morphometry was performed to compare gray matter (GM) volume, alongside measurement of cortical thickness and subcortical volumes. Saliva analyses revealed distinct alterations following BINT, with significantly elevated testosterone and T/C ratio. Widespread and largely symmetric loci of reduced GM were found specific to BINT, particularly in the temporal gyrus, precuneus, and thalamus. These findings suggest that BINT affects hypothalamic-pituitary-adrenal and -gonadal axis function, and causes anatomically-specific GM loss, which were not observed in a comparator group with similar occupational stressors. These findings support BINT as a unique injury with distinct structural and endocrine consequences.

Evaluating the implementation of robotic thoracic surgery on a Veterans Administration Hospital

Robotic thoracic surgery has demonstrated benefits. We aimed to evaluate implementation of a robotic thoracic surgery program on postoperative outcomes at our Veteran’s Administration Medical Center (VAMC). We retrospectively reviewed our VAMC database from 2015 to 2021. Patients who underwent surgery with intention to treat lung nodules were included. Primary outcome was patient length of stay (LOS). Patients were grouped by surgical approach and stratified to before and after adoption of robotic surgery. Univariate comparison of postoperative outcomes was performed using Wilcoxon rank sums and chi-squared tests. Multivariate regression was performed to control for ASA class. P values < 0.05 were considered significant. Outcomes of 108 patients were assessed. 63 operations (58%) occurred before and 45 (42%) after robotic surgery implementation. There were no differences in patient preoperative characteristics. More patients underwent minimally invasive surgery (MIS) in the post-implementation era than pre-implementation (85% vs. 42%, p < 0.001). Robotic operations comprised 53% of operations post-implementation. On univariate analysis, patients in the post-implementation era had a shorter LOS vs. pre-implementation, regardless of surgical approach (mean 4.7 vs. 6.0 days, p = 0.04). On multivariate analysis, patients who underwent MIS had a shorter LOS [median 4 days (IQR 2–6 days) vs. 7 days (6–9 days), p < 0.001] and were more likely to be discharged home than to inpatient facilities [OR (95% CI) 13.00 (1.61–104.70), p = 0.02]. Robotic thoracic surgery program implementation at a VAMC decreased patient LOS and increased the likelihood of discharging home. Implementation at other VAMCs may be associated with improvement in some patient outcomes.

Accelerated longitudinal cortical atrophy in OEF / OIF / OND veterans with severe PTSD and the impact of comorbid TBI

Veterans who deployed in support of Operation Enduring Freedom (OEF), Iraqi Freedom (OIF), and New Dawn (OND) commonly experience severe psychological trauma, often accompanied by physical brain trauma resulting in mild traumatic brain injury (mTBI). Prior studies of individuals with posttraumatic stress disorder (PTSD) have revealed alterations in brain structure, accelerated cellular aging, and impacts on cognition following exposure to severe psychological trauma and potential interactive effects of military‐related mTBI. To date, however, little is known how such deployment‐related trauma changes with time and age of injury of the affected veteran. In this study, we explored changes in cortical thickness, volume, and surface area after an average interval of approximately 2 years in a cohort of 254 OEF/OIF/OND Veterans ranging in age from 19 to 67 years. Whole‐brain vertex‐wise analyses revealed that veterans who met criteria for severe PTSD (Clinician‐Administered PTSD Scale ≥60) at baseline showed greater negative longitudinal changes in cortical thickness, volume, and area over time. Analyses also revealed a significant severe‐PTSD by age interaction on cortical measures with severe‐PTSD individuals exhibiting accelerated cortical degeneration with increasing age. Interaction effects of comorbid military‐related mTBI within the severe‐PTSD group were also observed in several cortical regions. These results suggest that those exhibiting severe PTSD symptomatology have accelerated atrophy that is exacerbated with increasing age and history of mTBI.

Life Event Stress and Reduced Cortical Thickness in Youth at Clinical High Risk for Psychosis and Healthy Control Subjects

BACKGROUND

A decline in cortical thickness during early life appears to be a normal neuromaturational process. Accelerated cortical thinning has been linked with conversion to psychosis among individuals at clinical high risk for psychosis (CHR-P). Previous research indicates that exposure to life event stress (LES) is associated with exaggerated cortical thinning in both healthy and clinical populations, and LES is also linked with conversion to psychosis in CHR-P. To date, there are no reports on the relationship of LES with cortical thickness in CHR-P. This study examines this relationship and whether LES is linked with cortical thinning to a greater degree in individuals at CHR-P who convert to psychosis compared with individuals at CHR-P who do not convert and healthy control subjects.

METHODS

Controlling for age and gender (364 male, 262 female), this study examined associations between LES and baseline cortical thickness in 436 individuals at CHR-P (375 nonconverters and 61 converters) and 190 comparison subjects in the North American Prodrome Longitudinal Study.

RESULTS

Findings indicate that prebaseline cumulative LES is associated with reduced baseline cortical thickness in several regions among the CHR-P and control groups. Evidence suggests that LES is a risk factor for thinner cortex to the same extent across diagnostic groups, while CHR-P status is linked with thinner cortex in select regions after accounting for LES.

CONCLUSIONS

This research provides additional evidence to support the role of LES in cortical thinning in both healthy youth and those at CHR-P. Potential underlying mechanisms of the findings and implications for future research are discussed.

Prefrontal cortex, amygdala, and threat processing: implications for PTSD

Posttraumatic stress disorder can be viewed as a disorder of fear dysregulation. An abundance of research suggests that the prefrontal cortex is central to fear processing-that is, how fears are acquired and strategies to regulate or diminish fear responses. The current review covers foundational research on threat or fear acquisition and extinction in nonhuman animals, healthy humans, and patients with posttraumatic stress disorder, through the lens of the involvement of the prefrontal cortex in these processes. Research harnessing advances in technology to further probe the role of the prefrontal cortex in these processes, such as the use of optogenetics in rodents and brain stimulation in humans, will be highlighted, as well other fear regulation approaches that are relevant to the treatment of posttraumatic stress disorder and involve the prefrontal cortex, namely cognitive regulation and avoidance/active coping. Despite the large body of translational research, many questions remain unanswered and posttraumatic stress disorder remains difficult to treat. We conclude by outlining future research directions related to the role of the prefrontal cortex in fear processing and implications for the treatment of posttraumatic stress disorder.

Assessment of brain age in posttraumatic stress disorder: Findings from the ENIGMA PTSD and brain age working groups

BACKGROUND

Posttraumatic stress disorder (PTSD) is associated with markers of accelerated aging. Estimates of brain age, compared to chronological age, may clarify the effects of PTSD on the brain and may inform treatment approaches targeting the neurobiology of aging in the context of PTSD.

METHOD

Adult subjects (N = 2229; 56.2% male) aged 18-69 years (mean = 35.6, SD = 11.0) from 21 ENIGMA-PGC PTSD sites underwent T1-weighted brain structural magnetic resonance imaging, and PTSD assessment (PTSD+, n = 884). Previously trained voxel-wise (brainageR) and region-of-interest (BARACUS and PHOTON) machine learning pipelines were compared in a subset of control subjects (n = 386). Linear mixed effects models were conducted in the full sample (those with and without PTSD) to examine the effect of PTSD on brain predicted age difference (brain PAD; brain age - chronological age) controlling for chronological age, sex, and scan site.

RESULTS

BrainageR most accurately predicted brain age in a subset (n = 386) of controls (brainageR: ICC = 0.71, R = 0.72, MAE = 5.68; PHOTON: ICC = 0.61, R = 0.62, MAE = 6.37; BARACUS: ICC = 0.47, R = 0.64, MAE = 8.80). Using brainageR, a three-way interaction revealed that young males with PTSD exhibited higher brain PAD relative to male controls in young and old age groups; old males with PTSD exhibited lower brain PAD compared to male controls of all ages.

DISCUSSION

Differential impact of PTSD on brain PAD in younger versus older males may indicate a critical window when PTSD impacts brain aging, followed by age-related brain changes that are consonant with individuals without PTSD. Future longitudinal research is warranted to understand how PTSD impacts brain aging across the lifespan.

Whole-brain morphometry in Canadian soldiers with posttraumatic stress disorder

Patients with posttraumatic stress disorder (PTSD) display several structural brain differences when compared with healthy individuals. However, findings are particularly inconsistent for soldiers with PTSD. Here, we characterized the brain morphometry of 37 soldiers from the Canadian Armed Forces with adulthood war-related PTSD using structural magnetic resonance imaging. We assessed time since trauma, as well as PTSD, depressive, and anxiety symptoms with the Modified PTSD Symptoms Scale, Beck Depression Inventory, and Beck Anxiety Inventory, respectively. Whole-brain morphometry was extracted with FreeSurfer and compared with a validated normative database of more than 2700 healthy individuals. Volume and thickness from several regions differed from the norms. Frontal regions were smaller and thinner, particularly the superior and rostral middle frontal gyri. Furthermore, smaller left rostral middle frontal gyrus, left pericalcarine cortex, and right fusiform gyrus were associated with more recent trauma. All subcortical structures were bigger, except the hippocampus. These findings suggest a particular brain morphometric signature of PTSD in soldiers. Smaller and thinner frontal and larger subcortical regions support impaired top-down and/or downregulation of emotional response in PTSD. Finally, the correlation of smaller frontal, temporal, and occipital regions with more recent trauma might inform future therapeutic approaches.

Nanodelivery of oxiracetam enhances memory, functional recovery and induces neuroprotection following concussive head injury

Military personnel are the most susceptible to concussive head injury (CHI) caused by explosion, blast or missile or blunt head trauma. Mild to moderate CHI could induce lifetime functional and cognitive disturbances causing significant decrease in quality of life. Severe CHI leads to instant death and lifetime paralysis. Thus, further exploration of novel therapeutic agents or new features of known pharmacological agents are needed to enhance quality of life of CHI victims. Previous reports from our laboratory showed that mild CHI induced by weight drop technique causing an impact of 0.224N results in profound progressive functional deficit, memory impairment and brain pathology from 5h after trauma that continued over several weeks of injury. In this investigation we report that TiO2 nanowired delivery of oxiracetam (50mg/kg, i.p.) daily for 5 days after CHI resulted in significant improvement of functional deficit on the 8th day. This was observed using Rota Rod treadmill, memory improvement assessed by the time spent in finding hidden platform under water. The motor function improvement is seen in oxiracetam treated CHI group by placing forepaw on an inclined mesh walking and foot print analysis for stride length and distance between hind feet. TiO2-nanowired oxiracetam also induced marked improvements in the cerebral blood flow, reduction in the BBB breakdown and edema formation as well as neuroprotection of neuronal, glial and myelin damages caused by CHI at light and electron microscopy on the 7th day after 5 days TiO2 oxiracetam treatment. Adverse biochemical events such as upregulation of CSF nitrite and nitrate, IL-6, TNF-a and p-Tau are also reduced significantly in oxiracetam treated CHI group. On the other hand post treatment of 100mg/kg dose of normal oxiracetam in identical conditions after CHI is needed to show slight but significant neuroprotection together with mild recovery of memory function and functional deficits on the 8th day. These observations are the first to point out that nanowired delivery of oxiracetam has superior neuroprotective ability in CHI. These results indicate a promising clinical future of TiO2 oxiracetam in treating CHI patients for better quality of life and neurorehabilitation, not reported earlier.

αCaMKII in the lateral amygdala mediates PTSD-Like behaviors and NMDAR-Dependent LTD

Post-traumatic stress disorder (PTSD) is a psychiatric disorder that afflicts many individuals. However, its molecular and cellular mechanisms remain largely unexplored. Here, we found PTSD susceptible mice exhibited significant up-regulation of alpha-Ca²⁺/calmodulin-dependent kinase II (αCaMKII) in the lateral amygdala (LA). Consistently, increasing αCaMKII in the LA not only caused PTSD-like behaviors such as impaired fear extinction and anxiety-like behaviors, but also attenuated N-methyl-D-aspartate receptor (NMDAR)-dependent long-term depression (LTD) at thalamo-lateral amygdala (T-LA) synapses, and reduced GluA1-Ser845/Ser831 dephosphorylation and a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) internalization. Suppressing the elevated αCaMKII to normal levels completely rescued both PTSD-like behaviors and the impairments in LTD, GluA1-Ser845/Ser831 dephosphorylation, and AMPAR internalization. Intriguingly, deficits in GluA1-Ser845/Ser831 dephosphorylation and AMPAR internalization were detected not only after impaired fear extinction, but also after attenuated LTD. Our results suggest that αCaMKII in the LA may be a potential molecular determinant of PTSD. We further demonstrate for the first time that GluA1-Ser845/Ser831 dephosphorylation and AMPAR internalization are molecular links between fear extinction and LTD.

Assessment of Neuropsychological Function in Veterans With Blast-Related Mild Traumatic Brain Injury and Subconcussive Blast Exposure

Objective: The majority of combat-related head injuries are associated with blast exposure. While Veterans with mild traumatic brain injury (mTBI) report cognitive complaints and exhibit poorer neuropsychological performance, there is little evidence examining the effects of subconcussive blast exposure, which does not meet clinical symptom criteria for mTBI during the acute period following exposure. We compared chronic effects of combat-related blast mTBI and combat-related subconcussive blast exposure on neuropsychological performance in Veterans. Methods: Post-9/11 Veterans with combat-related subconcussive blast exposure (n = 33), combat-related blast mTBI (n = 26), and controls (n = 33) without combat-related blast exposure, completed neuropsychological assessments of intellectual and executive functioning, processing speed, and working memory via NIH toolbox, assessment of clinical psychopathology, a retrospective account of blast exposures and non-blast-related head injuries, and self-reported current medication. Huber Robust Regressions were employed to compare neuropsychological performance across groups. Results: Veterans with combat-related blast mTBI and subconcussive blast exposure displayed significantly slower processing speed compared with controls. After adjusting for post-traumatic stress disorder and depressive symptoms, those with combat-related mTBI exhibited slower processing speed than controls. Conclusion: Veterans in the combat-related blast mTBI group exhibited slower processing speed relative to controls even when controlling for PTSD and depression. Cognition did not significantly differ between subconcussive and control groups or subconcussive and combat-related blast mTBI groups. Results suggest neurocognitive assessment may not be sensitive enough to detect long-term effects of subconcussive blast exposure, or that psychiatric symptoms may better account for cognitive sequelae following combat-related subconcussive blast exposure or combat-related blast mTBI.

Neuroimaging markers of adolescent depression in the National Consortium on Alcohol and Neurodevelopment in Adolescence (NCANDA) study

BACKGROUND

Adolescents are at increased risk of developing major depressive disorder (MDD) than many other age groups. Although the neural correlates of MDD in adults have been studied prospectively, such adolescent depression studies are mainly cross-sectional. We extracted data regarding the relationship between cortical thickness and later development of adolescent MDD from a national community study that uses an accelerated longitudinal design to examine the psychological, environmental, and neural differences related to drinking and brain development.

METHODS

692 subjects (age 12-21 years; 50% female) without a history of MDD were assessed with structural neuroimaging at baseline. We compared those 101 subjects who transitioned to MDD by 1-year follow-up to those who remained non-depressed over the same time period. FreeSurfer's autosegmentation process estimated vertex-wide cortical thicknesses and its Query, Design, Estimate, Contrast (Qdec) application investigated cortical thickness between those who later developed MDD and those who remained without MDD (Monte Carlo corrected for multiple comparisons, vertex-wise cluster threshold of 1.3, p < 0.01).

RESULTS

Those who transitioned in the next year to MDD had, at baseline, thinner cortices in the superior frontal cortex, precentral and postcentral regions, and superior temporal cortex, above and beyond effects attributable to age and sex. No cortical thickness sex differences or sex-by-depression interactions were observed.

LIMITATIONS

A larger sample size could improve statistical power and future investigations will be needed to confirm our results.

CONCLUSIONS

Thinner cortices over frontal and temporal regions may be linked to enhanced vulnerability for future depression during the adolescent-young adulthood transition.

Regional Cerebral Cortical Atrophy is Related to Urinary Tract Symptoms in Parkinson's Disease

BACKGROUND AND PURPOSE

Lower urinary tract symptoms (LUTS) are the most common nonmotor symptoms usually occurring mid-stage of Parkinson's disease (PD); however, its underlying mechanisms are unknown. We aimed to assess whether corticometry or volumetry can identify a pattern of cerebral cortical changes in PD patients with LUTS.

METHODS

We recruited 85 idiopathic PD patients and performed corticometry and volumetry on various cortical regions using each patient's magnetic resonance imaging. To identify a correlation between the cortical thickness/volume and nonmotor symptoms scale domain 7 scores, which represent the severity of LUTS, we performed general linear model and region of interest analyses.

RESULTS

Significant regional thinning of the left precuneus, left temporal pole, left precentral, right precuneus, and right pars opercularis was correlated with nonmotor symptoms scale domain 7 scores. We also found that cortical volumes of left precuneus and left frontal pole were inversely correlated with the severity of urinary symptoms.

CONCLUSIONS

This study showed that the thicknesses and volumes of several cortical regions were significantly correlated with the severity of LUTS in PD patients. The findings of regional atrophy and thinning of specific cortical regions in this study provide additional evidence that multiple cortical regions, especially the precuneus cortex, not only may be involved in urinary dysfunctions of PD patients but also may help to elucidate the exact underlying mechanisms for LUTS in PD patients.

Mechanisms Underlying Unconscious Processing and Their Alterations in Post-traumatic Stress Disorder: Neuroimaging of Zero Monetary Outcomes Contextually Framed as "No Losses" vs. "No Gains"

Although unconscious processing is a key element of mental operation, its neural correlates have not been established. Also, clinical observations suggest that unconscious processing may be involved in the pathophysiology of post-traumatic stress disorder (PTSD), but the neurobiological mechanisms underlying such impairments remain unknown. The purpose of the present study was to examine putative mechanisms underlying unconscious processing by healthy participants and to determine whether these mechanisms may be altered in PTSD patients. Twenty patients with PTSD and 27 healthy individuals were administered a validated wheel of fortune-type gambling task during functional magnetic resonance imaging (fMRI). Unconscious processing was elicited using unconscious contextual framing of the zero monetary outcomes as "no loss," "no gain" or as "neutral." Brief passive visual processing of the "no loss" vs. "no gain" contrast by healthy participants yielded bilateral frontal-, temporal- and insular cortices and striatal activations. Between-group comparison revealed smaller activity in the left anterior prefrontal-, left dorsolateral prefrontal-, right temporal- and right insular cortices and in bilateral striatum in PTSD patients with the left dorsolateral prefrontal cortex activity been more pronounced in those with greater PTSD severity. These observations implicate frontal-, temporal-, and insular cortices along with the striatum in the putative mechanisms underlying unconscious processing of the monetary outcomes. Additionally, our results support the hypothesis that PTSD is associated with primary cortical and subcortical alterations involved in the above processes and that these alterations may be related to some aspects of PTSD symptomatology.

Functional and Structural Neuroimaging Correlates of Repetitive Low-Level Blast Exposure in Career Breachers

Combat military and civilian law enforcement personnel may be exposed to repetitive low-intensity blast events during training and operations. Persons who use explosives to gain entry (i.e., breach) into buildings are known as “breachers” or dynamic entry personnel. Breachers operate under the guidance of established safety protocols, but despite these precautions, breachers who are exposed to low-level blast throughout their careers frequently report performance deficits and symptoms to healthcare providers. Although little is known about the etiology linking blast exposure to clinical symptoms in humans, animal studies demonstrate network-level changes in brain function, alterations in brain morphology, vascular and inflammatory changes, hearing loss, and even alterations in gene expression after repeated blast exposure. To explore whether similar effects occur in humans, we collected a comprehensive data battery from 20 experienced breachers exposed to blast throughout their careers and 14 military and law enforcement controls. This battery included neuropsychological assessments, blood biomarkers, and magnetic resonance imaging measures, including cortical thickness, diffusion tensor imaging of white matter, functional connectivity, and perfusion. To better understand the relationship between repetitive low-level blast exposure and behavioral and imaging differences in humans, we analyzed the data using similarity-driven multi-view linear reconstruction (SiMLR). SiMLR is specifically designed for multiple modality statistical integration using dimensionality-reduction techniques for studies with high-dimensional, yet sparse, data (i.e., low number of subjects and many data per subject). We identify significant group effects in these data spanning brain structure, function, and blood biomarkers.