Disruption of white matter structural integrity and connectivity in posttraumatic stress disorder: A TBSS and tractography study

Neuroimaging of posttraumatic stress disorder in adults and youth: progress over the last decade on three leading questions of the field

Almost three decades have passed since the first posttraumatic stress disorder (PTSD) neuroimaging study was published. Since then, the field of clinical neuroscience has made advancements in understanding the neural correlates of PTSD to create more efficacious treatment strategies. While gold-standard psychotherapy options are available, many patients do not respond to them, prematurely drop out, or never initiate treatment. Therefore, elucidating the neurobiological mechanisms that define the disorder can help guide clinician decision-making and develop individualized mechanisms-based treatment options. To this end, this narrative review highlights progress made in the last decade in adult and youth samples on three outstanding questions in PTSD research: (1) Which neural alterations serve as predisposing (pre-exposure) risk factors for PTSD development, and which are acquired (post-exposure) alterations? (2) Which neural alterations can predict treatment outcomes and define clinical improvement? and (3) Can neuroimaging measures be used to define brain-based biotypes of PTSD? While the studies highlighted in this review have made progress in answering the three questions, the field still has much to do before implementing these findings into clinical practice. Overall, to better answer these questions, we suggest that future neuroimaging studies of PTSD should (A) utilize prospective longitudinal designs, collecting brain measures before experiencing trauma and at multiple follow-up time points post-trauma, taking advantage of multi-site collaborations/consortiums; (B) collect two scans to explore changes in brain alterations from pre-to-post treatment and compare changes in neural activation between treatment groups, including longitudinal follow up assessments; and (C) replicate brain-based biotypes of PTSD. By synthesizing recent findings, this narrative review will pave the way for personalized treatment approaches grounded in neurobiological evidence.

Affective Visual Circuit Dysfunction in Trauma and Stress-Related Disorders

Posttraumatic stress disorder (PTSD) is widely recognized as involving disruption of core neurocircuitry that underlies processing, regulation, and response to threat. In particular, the prefrontal cortex-hippocampal-amygdala circuit is a major contributor to posttraumatic dysfunction. However, the functioning of core threat neurocircuitry is partially dependent on sensorial inputs, and previous research has demonstrated that dense, reciprocal connections exist between threat circuits and the ventral visual stream. Furthermore, emergent evidence suggests that trauma exposure and resultant PTSD symptoms are associated with altered structure and function of the ventral visual stream. In the current review, we discuss evidence that both threat and visual circuitry together are an integral part of PTSD pathogenesis. An overview of the relevance of visual processing to PTSD is discussed in the context of both basic and translational research, highlighting the impact of stress on affective visual circuitry. This review further synthesizes emergent literature to suggest potential timing-dependent effects of traumatic stress on threat and visual circuits that may contribute to PTSD development. We conclude with recommendations for future research to move the field toward a more complete understanding of PTSD neurobiology.

Persistence of post-traumatic stress disorder in Chinese Shidu parents is associated with combined gray and white matter abnormalities

Post-traumatic stress disorder (PTSD) is one of the most common mental health disorders among Shidu parents. Identification of gray and white matter differences between persistence of PTSD (P-PTSD) and remission of PTSD (R-PTSD) is crucial to determine their prognosis. A total of 37 Shidu parents with PTSD were followed for five years. Surface-based morphometry and diffusion tensor imaging were carried out to analyze the differences in gray and white matter between P-PTSD and R-PTSD. Finally, 30 patients with PTSD were enrolled, including 12 with P-PTSD and 18 with R-PTSD. Compared with patients with R-PTSD, patients with P-PTSD exhibited lower fractional anisotropy (FA) in Cluster 1 (including body of the corpus callosum, superior longitudinal fasciculus, corticospinal tract) and Cluster 2 (including inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, splenium of the corpus callosum) in the left cerebral hemisphere and higher cortical thickness in the right lateral occipital cortex (LOC). In patients with P-PTSD, FA values of Cluster 2 were negatively correlated with cortical thickness of the right LOC. These results suggest that among Shidu parents, differences were observed in gray and white matter between P-PTSD and R-PTSD. Moreover, some certain gray and white matter abnormalities were often present simultaneously in P-PTSD.

Impact of PTSD and Obstructive Sleep Apnea on Cognition in Older Adult Veterans

Background: Posttraumatic stress disorder (PTSD) and obstructive sleep apnea (OSA) are highly prevalent and comorbid among older adult male veterans. Both PTSD and OSA are independently associated with cognitive deficits in older adults, but little research regarding the impact of comorbid PTSD and OSA among older adults exists. Purpose: The current study aimed to examine the independent and interactive effects of PTSD and OSA on cognitive functioning in older adult veterans. Study Sample: Older adult male veterans with (n = 106) and without PTSD (n = 69), ranging in age from 55 to 89 (M = 63.35). Data Collection: Participants underwent polysomnography evaluation to assess severity of OSA symptoms and comprehensive neuropsychological evaluation to assess cognitive functioning in 3 domains: attention and processing speed, learning and memory, and executive functioning. Results: Multiple regression analyses showed that the interaction between PTSD and OSA did not predict cognitive performance. However, PTSD significantly predicted poorer attention and processing speed, and increased OSA severity predicted poorer learning and memory. Conclusions: While PTSD and OSA did not have a synergistic detrimental impact on cognition, each independently predicted poorer cognitive functioning within certain domains, suggesting that older adults with these comorbid conditions may experience a wider array of cognitive difficulties.

Hybrid Deep Learning Approach for Stress Detection Using Decomposed EEG Signals

Stress has an impact, not only on a person's physical health, but also on the ability to perform at the workplace in daily life. The well-established relation between psychological stress and its pathogeneses highlights the need for detecting psychological stress early, in order to prevent disease advancement and to save human lives. Electroencephalography (EEG) signal recording tools are widely used to collect these psychological signals/brain rhythms in the form of electric waves. The aim of the current research was to apply automatic feature extraction to decomposed multichannel EEG recordings, in order to efficiently detect psychological stress. The traditional deep learning techniques, namely the convolution neural network (CNN), long short-term memory (LSTM), bidirectional long short-term memory (BiLSTM), gated recurrent unit (GRU) and recurrent neural network (RNN) models, have been frequently used for stress detection. A hybrid combination of these techniques may provide improved performance, and can handle long-term dependencies in non-linear brain signals. Therefore, this study proposed an integration of deep learning models, called DWT-based CNN, BiLSTM, and two layers of a GRU network, to extract features and classify stress levels. Discrete wavelet transform (DWT) analysis was used to remove the non-linearity and non-stationarity from multi-channel (14 channel) EEG recordings, and to decompose them into different frequency bands. The decomposed signals were utilized for automatic feature extraction using the CNN, and the stress levels were classified using BiLSTM and two layers of GRU. This study compared five combinations of the CNN, LSTM, BiLSTM, GRU and RNN models with the proposed model. The proposed hybrid model performed better in classification accuracy compared to the other models. Therefore, hybrid combinations are appropriate for the clinical intervention and prevention of mental and physical problems.

Sleep Quality Disturbances Are Associated with White Matter Alterations in Veterans with Post-Traumatic Stress Disorder and Mild Traumatic Brain Injury

Sleep disturbances are strongly associated with mild traumatic brain injury (mTBI) and post-traumatic stress disorder (PTSD). PTSD and mTBI have been linked to alterations in white matter (WM) microstructure, but whether poor sleep quality has a compounding effect on WM remains largely unknown. We evaluated sleep and diffusion magnetic resonance imaging (dMRI) data from 180 male post-9/11 veterans diagnosed with (1) PTSD (n = 38), (2) mTBI (n = 25), (3) comorbid PTSD+mTBI (n = 94), and (4) a control group with neither PTSD nor mTBI (n = 23). We compared sleep quality (Pittsburgh Sleep Quality Index, PSQI) between groups using ANCOVAs and calculated regression and mediation models to assess associations between PTSD, mTBI, sleep quality, and WM. Veterans with PTSD and comorbid PTSD+mTBI reported poorer sleep quality than those with mTBI or no history of PTSD or mTBI (p = 0.012 to <0.001). Poor sleep quality was associated with abnormal WM microstructure in veterans with comorbid PTSD+mTBI (p < 0.001). Most importantly, poor sleep quality fully mediated the association between greater PTSD symptom severity and impaired WM microstructure (p < 0.001). Our findings highlight the significant impact of sleep disturbances on brain health in veterans with PTSD+mTBI, calling for sleep-targeted interventions.

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.

Hyperbaric oxygen therapy improves symptoms, brain's microstructure and functionality in veterans with treatment resistant post-traumatic stress disorder: A prospective, randomized, controlled trial

Introduction

Post-traumatic stress disorder (PTSD) is characterized by changes in both brain activity and microstructural integrity. Cumulative evidence demonstrates that hyperbaric oxygen therapy (HBOT) induces neuroplasticity and case-series studies indicate its potentially positive effects on PTSD. The aim of the study was to evaluate HBOT’s effect in veterans with treatment resistant PTSD.

Methods

Veterans with treatment resistant PTSD were 1:1 randomized to HBOT or control groups. All other brain pathologies served as exclusion criteria. Outcome measures included clinician-administered PTSD scale-V (CAPS-V) questionnaires, brief symptom inventory (BSI), BECK depression inventory (BDI), brain microstructural integrity evaluated by MRI diffuse tensor imaging sequence (DTI), and brain function was evaluated by an n-back task using functional MRI (fMRI). The treatment group underwent sixty daily hyperbaric sessions. No interventions were performed in the control group.

Results

Thirty-five veterans were randomized to HBOT (N = 18) or control (n = 17) and 29 completed the protocol. Following HBOT, there was a significant improvement in CAPS-V scores and no change in the control (F = 30.57, P<0.0001, Net effect size = 1.64). Significant improvements were also demonstrated in BSI and BDI scores (F = 5.72, P = 0.024 Net effect size = 0.89, and F = 7.65, P = 0.01, Net effect size = 1.03). Improved brain activity was seen in fMRI in the left dorsolateral prefrontal, middle temporal gyri, both thalami, left hippocampus and left insula. The DTI showed significant increases in fractional anisotropy in the fronto-limbic white-matter, genu of the corpus callosum and fornix.

Conclusions

HBOT improved symptoms, brain microstructure and functionality in veterans with treatment resistant PTSD.

White matter microstructure and volume correlates of premenstrual dysphoric disorder

BACKGROUND

Premenstrual dysphoric disorder (PMDD) is a mood disorder characterized by psychological and physical symptoms. Differences in white matter have been associated with affective and anxiety disorders, which share some symptoms with PMDD. However, whether white matter structure differs between the brains of individuals with PMDD and healthy controls is not known, nor is its relation to symptom severity.

METHODS

We performed tract-based spatial statistics and voxel-based morphometry analyses of diffusion tensor imaging metrics and white matter volume, using 2 neuroimaging data sets (n = 67 and n = 131) and a combined whole-brain and region-of-interest approach. We performed correlation analyses to investigate the relationship between regions with different white matter microstructure and volume and PMDD symptom severity.

RESULTS

We found greater fractional anisotropy in the left uncinate fasciculus (d = 0.69) in individuals with PMDD compared to controls. Moreover, the volume of the right uncinate fasciculus was higher in individuals with PMDD compared to controls (d = 0.40). As well, the severity of premenstrual depression was positively correlated with fractional anisotropy in the right superior longitudinal fasciculus (r = 0.35).

LIMITATIONS

It is challenging to interpret group differences in diffusion tensor imaging metrics in terms of their underlying biophysical properties. The small size of the control group in the diffusion tensor imaging study may have prevented effects of interest from being detected.

CONCLUSION

The findings of the present study provide evidence of differential cerebral white matter structure associated with PMDD and its symptoms.

Acute Posttraumatic Symptoms Are Associated With Multimodal Neuroimaging Structural Covariance Patterns: A Possible Role for the Neural Substrates of Visual Processing in Posttraumatic Stress Disorder

BACKGROUND

Although aspects of brain morphology have been associated with chronic posttraumatic stress disorder (PTSD), limited work has investigated multimodal patterns in brain morphology that are linked to acute posttraumatic stress severity. In the present study, we utilized multimodal magnetic resonance imaging to investigate if structural covariance networks (SCNs) assessed acutely following trauma were linked to acute posttraumatic stress severity.

METHODS

Structural magnetic resonance imaging data were collected around 1 month after civilian trauma exposure in 78 participants. Multimodal magnetic resonance imaging data fusion was completed to identify combinations of SCNs, termed structural covariance profiles (SCPs), related to acute posttraumatic stress severity collected at 1 month. Analyses assessed the relationship between participant SCP loadings, acute posttraumatic stress severity, the change in posttraumatic stress severity from 1 to 12 months, and depressive symptoms.

RESULTS

We identified an SCP that reflected greater gray matter properties of the anterior temporal lobe, fusiform face area, and visual cortex (i.e., the ventral visual stream) that varied curvilinearly with acute posttraumatic stress severity and the change in PTSD symptom severity from 1 to 12 months. The SCP was not associated with depressive symptoms.

CONCLUSIONS

We identified combinations of multimodal SCNs that are related to variability in PTSD symptoms in the early aftermath of trauma. The identified SCNs may reflect patterns of neuroanatomical organization that provide unique insight into acute posttraumatic stress. Furthermore, these multimodal SCNs may be potential candidates for neural markers of susceptibility to both acute posttraumatic stress and the future development of PTSD.

Synergistic Role of Quantitative Diffusion Magnetic Resonance Imaging and Structural Magnetic Resonance Imaging in Predicting Outcomes After Traumatic Brain Injury

OBJECTIVE

This study aimed to assess if quantitative diffusion magnetic resonance imaging analysis would improve prognostication of individual patients with severe traumatic brain injury.

METHODS

We analyzed images of 30 healthy controls to extract normal fractional anisotropy ranges along 18 white-matter tracts. Then, we analyzed images of 33 patients, compared their fractional anisotropy values with normal ranges extracted from controls, and computed severity of injury to white-matter tracts. We also asked 2 neuroradiologists to rate severity of injury to different brain regions on fluid-attenuated inversion recovery and susceptibility-weighted imaging. Finally, we built 3 models: (1) fed with neuroradiologists' ratings, (2) fed with white-matter injury measures, and (3) fed with both input types.

RESULTS

The 3 models respectively predicted survival at 1 year with accuracies of 70%, 73%, and 88%. The accuracy with both input types was significantly better (P < 0.05).

CONCLUSIONS

Quantifying severity of injury to white-matter tracts complements qualitative imaging findings and improves outcome prediction in severe traumatic brain injury.

Psychoradiological abnormalities in treatment-naive noncomorbid patients with posttraumatic stress disorder

BACKGROUND

Neuroimaging studies in posttraumatic stress disorder (PTSD) have identified various alterations in white matter (WM) microstructural organization. However, it remains unclear whether these are localized to specific regions of fiber tracts, and what diagnostic value they might have. This study set out to explore the spatial profile of WM abnormalities along defined fiber tracts in PTSD.

METHODS

Diffusion tensor images were obtained from 77 treatment-naive noncomorbid patients with PTSD and 76 demographically matched trauma-exposed non-PTSD (TENP) controls. Using automated fiber quantification, tract profiles of fractional anisotropy, axial diffusivity, mean diffusivity, and radial diffusivity were calculated to evaluate WM microstructural organization. Results were analyzed by pointwise comparisons, by correlation with symptom severity, and for diagnosis-by-sex interactions. Support vector machine analyses assessed the ability of tract profiles to discriminate PTSD from TENP.

RESULTS

Compared to TENP, PTSD showed lower fractional anisotropy accompanied by higher radial diffusivity and mean diffusivity in the left uncinate fasciculus, and lower fractional anisotropy accompanied by higher radial diffusivity in the right anterior thalamic radiation. Tract profile alterations were correlated with symptom severity, suggesting a pathophysiological relevance. There were no significant differences in diagnosis-by-sex interaction. Tract profiles allowed individual classification of PTSD versus TENP with significant accuracy, of potential diagnostic utility.

CONCLUSIONS

These findings add to the knowledge of the neuropathological basis of PTSD. WM alterations based on a tract-profile quantification approach are a potential biomarker for PTSD.

DTI Connectometry Analysis Reveals White Matter Changes in Cognitively Impaired World Trade Center Responders at Midlife

BACKGROUND

More than 8% of responders who participated in the search and rescue efforts at the World Trade Center (WTC) following 9/11 developed early-onset cognitive impairment (CI). Approximately 23% were also diagnosed with chronic post-traumatic stress disorder (PTSD).

OBJECTIVE

To shed light on the pathophysiology of these WTC-related conditions, we examined diffusion connectometry to identify altered white matter tracts in WTC responders with CI and/or PTSD compared to unaffected responders.

METHODS

99 WTC responders (mean age 56 years) consisting of CI-/PTSD- (n = 27), CI+/PTSD- (n = 25), CI-/PTSD+ (n = 24), and CI+/PTSD+ (n = 23) were matched on age, sex, occupation, race, and education. Cognitive status was determined using the Montreal Cognitive Assessment and PTSD status was determined using the DSM-IV SCID. Diffusion tensor imaging was acquired on a 3T Siemens Biograph mMR scanner. Connectometry analysis was used to examine whole-brain tract-level differences in white matter integrity as reflected by fractional anisotropy (FA) values after adjusting for confounders.

RESULTS

Analyses identified that FA was negatively correlated with CI and PTSD status in the fornix, cingulum, forceps minor of the corpus callosum and the right uncinate fasciculus. Furthermore, FA was negatively correlated with PTSD status, regardless of CI status in the superior thalamic radiation and the cerebellum.

CONCLUSION

This is the first connectometry study to examine altered white matter tracts in a sample of WTC responders with CI and/or PTSD. Results from this study suggest that WTC responders with early-onset CI may be experiencing an early neurodegenerative process characterized by decreased FA in white matter tracts.

Pediatric PTSD is characterized by age- and sex-related abnormalities in structural connectivity

Pediatric post-traumatic stress disorder (pPTSD) is a prevalent and pervasive form of mental illness comprising a disparate constellation of psychiatric symptoms. Emerging evidence suggests that pPTSD may be characterized by alterations in functional networks traversing the brain. Yet, little is known about pathological changes in the structural tracts underlying functional connectivity. In adults, PTSD is linked to widespread change in white matter integrity throughout the brain, yet similar studies with youth populations have yet to be conducted. Current understanding of the nature and treatment of pPTSD may be enhanced by examining alterations in white matter, while further untangling effects of age and sex. Here, we assess the microstructure of 12 major white matter tracts in a sample of well-phenotyped youth with PTSD. Measures of fractional anisotropy were derived from diffusion tensor images acquired from 82 unmediated youth (ages 8-18), of whom 39 met criteria for pPTSD. Diagnosis of pPTSD was linked to remarkable age- and sex-linked differences in the microstructure of major white matter tracts including the uncinate fasciculus, cingulum bundle, and inferior longitudinal fasciculus. In each case, youth with PTSD show an absence of increased white matter integrity with age, suggesting an altered pattern of neurodevelopment that may contribute to persistence or worsening of illness. Broadly, our results suggest abnormal white matter development in pediatric PTSD, a finding which may contribute to illness persistence, comorbidity with other disorders, and poorer prognosis across time. Critically, these findings further speak to the nature of pPTSD as a 'whole-brain' disorder.

Altered white matter microstructural organization in posttraumatic stress disorder across 3047 adults: results from the PGC-ENIGMA PTSD consortium

A growing number of studies have examined alterations in white matter organization in people with posttraumatic stress disorder (PTSD) using diffusion MRI (dMRI), but the results have been mixed which may be partially due to relatively small sample sizes among studies. Altered structural connectivity may be both a neurobiological vulnerability for, and a result of, PTSD. In an effort to find reliable effects, we present a multi-cohort analysis of dMRI metrics across 3047 individuals from 28 cohorts currently participating in the PGC-ENIGMA PTSD working group (a joint partnership between the Psychiatric Genomics Consortium and the Enhancing NeuroImaging Genetics through Meta-Analysis consortium). Comparing regional white matter metrics across the full brain in 1426 individuals with PTSD and 1621 controls (2174 males/873 females) between ages 18-83, 92% of whom were trauma-exposed, we report associations between PTSD and disrupted white matter organization measured by lower fractional anisotropy (FA) in the tapetum region of the corpus callosum (Cohen's d = -0.11, p = 0.0055). The tapetum connects the left and right hippocampus, for which structure and function have been consistently implicated in PTSD. Results were consistent even after accounting for the effects of multiple potentially confounding variables: childhood trauma exposure, comorbid depression, history of traumatic brain injury, current alcohol abuse or dependence, and current use of psychotropic medications. Our results show that PTSD may be associated with alterations in the broader hippocampal network.

A unifying translational framework to advance treatment research for comorbid PTSD and substance use disorders

We provide a unifying translational framework that can be used to synthesize extant lines of human laboratory research in four neurofunctional domains that underlie the co-occurrence of posttraumatic stress and substance use disorders (PTSD+SUD). We draw upon the Alcohol and Addiction Research Domain Criteria (AARDOC) to include executive functioning, negative emotionality, reward, and added social cognition from the National Institute of Mental Health (NIMH) Research Domain Criteria into our framework. We review research findings across each of the four domains, emphasizing human experimental studies in PTSD, SUD, and PTSD+SUD for each domain. We also discuss the implications of research findings for treatment development by considering new ways of conceptualizing risk factors and outcomes at the level of the individual patient, which will enhance treatment matching and advance innovations in intervention.

White Matter Alterations Are Associated With Cognitive Dysfunction Decades After Moderate-to-Severe Traumatic Brain Injury and/or Posttraumatic Stress Disorder

BACKGROUND

Possible white matter (WM) alterations following moderate-to-severe traumatic brain injury (TBI) and posttraumatic stress disorder (PTSD) and their relationship to clinical outcome have yet to be investigated decades after trauma. We utilized structural magnetic resonance imaging and diffusion tensor images to investigate brain volume and WM alterations in Vietnam War veterans with moderate-to-severe TBI and/or PTSD examined 5 decades after trauma.

METHODS

Data from 160 veterans-history of moderate-to-severe TBI (n = 23), history of TBI+PTSD (n = 36), history of PTSD (n = 53), and control veterans (n = 48)-were obtained from the Department of Defense Alzheimer's Disease Neuroimaging Initiative database. Voxel-based morphometry and tract-based spatial statistics were used to investigate ongoing brain morphometry and WM abnormalities. The fractional anisotropy (FA) and mean diffusivity were then correlated with neuropsychological scores and amyloid deposition in the trauma groups.

RESULTS

Compared with control subjects, the three trauma groups showed gray matter atrophy, lower FA, and distinctly higher diffusivity in the major WM tracts, including the corpus callosum, external and internal capsules, cingulum, and inferior and superior longitudinal fasciculi. The FA and mean diffusivity correlated with cognitive deficits in the trauma groups. Furthermore, the FA in the cingulum correlated negatively with amyloid deposition in the posterior cingulate cortex of all three trauma groups.

CONCLUSIONS

Diffusion tensor imaging detected WM abnormalities that correlated with the severity of present cognitive dysfunction and the degree of cortical amyloid deposition decades after moderate-to-severe TBI and/or PTSD. These results may hint that PTSD secondary to TBI may incur late cognitive sequalae and persistence of brain microstructure alterations.

White matter microstructure varies with post-traumatic stress severity following medical trauma

The prefrontal cortex, amygdala, hippocampus, and hypothalamus are important components of the neural network that mediates the healthy learning, expression, and regulation of emotion. These brain regions are connected by white matter pathways that include the cingulum bundle, uncinate fasciculus, and fornix/stria terminalis. Individuals with trauma and stress-related disorders show dysfunction of the cognitive-affective processes supported by the brain regions these white matter tracts connect. Therefore, variability in the microstructure of these white matter pathways may play an important role in the cognitive-affective dysfunction related to post-traumatic stress disorder. Thus, the current study used diffusion weighted imaging to assess the white matter microstructure of the cingulum bundle, uncinate fasciculus, and fornix/stria terminalis acutely (< 1 month) following trauma. Further, we assessed both acute (i.e., < 1 month) and subacute (i.e., 3 months post-trauma) post-traumatic stress symptom severity. White matter microstructure (assessed < 1 month post-trauma) of the uncinate fasciculus and fornix/stria terminalis varied with acute post-traumatic stress severity (assessed < 1 month post-trauma). Further, white matter microstructure (assessed < 1 month post-trauma) of the cingulum bundle and fornix/stria terminalis varied with subacute post-traumatic stress severity (assessed 3 months post-trauma). The current results suggest white matter architecture of the prefrontal cortex - amygdala network plays an important role in the development of trauma and stress-related disorders.

Diffusion Tensor Imaging Reveals White Matter Differences in Military Personnel Exposed to Trauma with and without Post-traumatic Stress Disorder

BACKGROUND

Post-traumatic stress disorder (PTSD) is a debilitating mental health condition that develops in response to exposure to a traumatic event. The purpose of this study was to investigate white matter differences using diffusion tensor imaging (DTI) in trauma exposed military personnel with and without PTSD.

METHODS

Data were acquired in compliance with the Hospital for Sick Children and Canadian Armed Forces Research Ethics Boards for the following groups: military personnel with PTSD (PTSD, n = 23), trauma exposed military personnel with no PTSD diagnosis (TE, n = 25) and civilian controls (CC, n =13) . All participants were male. DTI was acquired on a Siemens Trio 3T MRI. Maps of Fractional Anisotropy (FA), Mean Diffusivity (MD), Axial Diffusivity (AD), and Radial Diffusivity (RD) were analyzed using Tract-Based Spatial Statistics (TBSS).

RESULTS

In the PTSD and TE groups, FA was significantly greater within the hippocampus, corpus callosum, cingulum, and several associated white matter tracts. Elevated FA was shown to be largely due to reduced RD suggesting a possible structural substrate that underscores neurophysiological connectivity.

CONCLUSIONS

This study reinforces previous findings showing differences in DTI metrics within the limbic system in military personnel exposed to trauma with and without PTSD.

Race, Socioeconomic Status, and Cerebellum Cortex Fractional Anisotropy in Pre-Adolescents

Introduction

Cerebellum cortex fractional anisotropy is a proxy of the integrity of the cerebellum cortex. However, less is known about how it is shaped by race and socioeconomic status (SES) indicators such as parental education and household income.

Purpose

In a national sample of American pre-adolescents, this study had two aims: to test the effects of two SES indicators, namely parental education and household income, on cerebellum cortex fractional anisotropy, and to explore racial differences in these effects.

Methods

Using data from the Adolescent Brain Cognitive Development (ABCD) study, we analyzed the diffusion Magnetic Resonance Imaging (dMRI) data of 9565, 9-10-year-old pre-adolescents. The main outcomes were cerebellum cortex fractional anisotropy separately calculated for right and left hemispheres using dMRI. The independent variables were parental education and household income; both treated as categorical variables. Age, sex, ethnicity, and family marital status were the covariates. Race was the moderator. To analyze the data, we used mixed-effects regression models without and with interaction terms. We controlled for propensity score and MRI device.

Results

High parental education and household income were associated with lower right and left cerebellum cortex fractional anisotropy. In the pooled sample, we found significant interactions between race and parental education and household income, suggesting that the effects of parental education and household income on the right and left cerebellum cortex fractional anisotropy are all significantly larger for White than for Black pre-adolescents.

Conclusions

The effects of SES indicators, namely parental education and household income, on pre-adolescents' cerebellum cortex microstructure and integrity are weaker in Black than in White families. This finding is in line with the Marginalization-related Diminished Returns (MDRs), defined as weaker effects of SES indicators for Blacks and other racial and minority groups than for Whites.

Chemotherapy-Induced Brain Effects in Small-Cell Lung Cancer Patients: A Multimodal MRI Study

The golden standard of treating Small Cell Lung Cancer (SCLC) entails application of platinum-based chemotherapy, is often accompanied by Prophylactic Cranial Irradiation (PCI), which have been linked to neurotoxic side-effects in cognitive functions. The related existing neuroimaging research mainly focuses on the effect of PCI treatment in life quality and expectancy, while little is known regarding the distinct adverse effects of chemotherapy. In this context, a multimodal MRI analysis based on structural and functional brain data is proposed in order to evaluate chemotherapy-specific effects on SCLC patients. Data from 20 patients (after chemotherapy and before PCI) and 14 healthy controls who underwent structural MRI, DTI and resting state fMRI were selected in this study. From a structural aspect, the proposed analysis included volumetry and thickness measurements on structural MRI data for assessing gray matter dissimilarities, as well as deterministic tractography and Tract-Based Spatial Statistics (TBSS) on DTI data, aiming to investigate potential white matter abnormalities. Functional data were also processed on the basis of connectivity analysis, evaluating brain network parameters to identify potential manifestation of functional inconsistencies. By comparing patients to healthy controls, the obtained results revealed statistically significant differences, with the patients' brains presenting reduced volumetry/thickness and fractional anisotropy values, accompanied by prominent differences in functional connectivity measurements. All above mentioned findings were observed in patients that underwent chemotherapy.

Hypnotizability and the Natural Human Ability to Alter Experience

There seems to be a natural, human ability to alter one's experience that already exists - prior to and apart from any hypnotic induction. Individual differences in this ability range from low to high and are largely commensurate with the person's assessed hypnotizability. More importantly, these preexisting, individual differences in the ability to alter experience seem to be the "substrate" that enables each individual's response to hypnotic suggestions. It is proposed that, with some notable exceptions, the hypnosis field's understanding of hypnotizability has been hindered by theorists' (and clinicians') tendency to consider the instruments that reveal hypnotic phenomena (i.e., hypnosis and suggestions) to be explanatory concepts.

Multimodal structural neuroimaging markers of risk and recovery from posttrauma anhedonia: A prospective investigation

BACKGROUND

Anhedonic symptoms of posttraumatic stress disorder (PTSD) reflect deficits in reward processing that have significant functional consequences. Although recent evidence suggests that disrupted integrity of fronto-limbic circuitry is related to PTSD development, including anhedonic PTSD symptoms (posttrauma anhedonia [PTA]), little is known about potential structural biomarkers of long-term PTA as well as structural changes in fronto-limbic pathways associated with recovery from PTA over time.

METHODS

We investigated associations between white matter microstructure, gray matter volume, and PTA in 75 recently traumatized individuals, with a subset of participants (n = 35) completing follow-up assessment 12 months after trauma exposure. Deterministic tractography and voxel-based morphometry were used to assess changes in white and gray matter structure associated with changes in PTA.

RESULTS

Reduced fractional anisotropy (FA) of the uncinate fasciculus at around the time of trauma predicted greater PTA at 12-months posttrauma. Further, increased FA of the fornix over time was associated with lower PTA between 1 and 12-months posttrauma. Increased gray matter volume of the ventromedial prefrontal cortex and precuneus over time was also associated with reduced PTA.

CONCLUSIONS

The microstructure of the uncinate fasciculus, an amygdala-prefrontal white matter connection, may represent a biomarker of vulnerability for later PTA. Conversely, development and recovery from PTA appear to be facilitated by white and gray matter structural changes in a major hippocampal pathway, the fornix. The present findings shed new light on neuroanatomical substrates of recovery from PTA and characterize white matter biomarkers of risk for posttraumatic dysfunction.

Magnetic resonance diffusion tensor imaging in psychiatry: a narrative review of its potential role in diagnosis

Diffusion tensor imaging (DTI) is an imaging technique that uses magnetic resonance. It measures the diffusion of water molecules in tissues, which can occur either without restriction (i.e., in an isotropic manner) or limited by some obstacles, such as cell membranes (i.e., in an anisotropic manner). Diffusion is most often measured in terms of, inter alia, fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD). DTI allows us to reconstruct, visualize, and evaluate certain qualities of white matter. To date, many studies have sought to associate various changes in the distribution of diffusion within the brain with mental diseases and disorders. A better understanding of white matter integrity disorders can help us recognize the causes of diseases, as well as help create objective methods of psychiatric diagnosis, identify biomarkers of mental illness, and improve pharmacotherapy. The aim of this work is to present the characteristics of DTI as well as current research on its use in schizophrenia, affective disorders, and other mental disorders.

Structural white and gray matter differences in a large sample of patients with Posttraumatic Stress Disorder and a healthy and trauma-exposed control group: Diffusion tensor imaging and region-based morphometry

Differences in structural white and gray matter in survivors of traumatic experiences have been related to the development and maintenance of Posttraumatic Stress Disorder (PTSD). However, there are very few studies on diffusion tensor imaging and region based morphometry comparing patients with PTSD to two control groups, namely healthy individuals with or without trauma experience. It is also unknown if differences in white and gray matter are associated. In this cross-sectional study, we examined white- and gray matter differences between 44 patients with PTSD, 49 trauma control and 61 healthy control subjects. We compared the groups applying Tract-Based Spatial Statistics (TBSS) for a whole brain white matter analysis as well as region of interest analyses for white and gray matter. First, trauma control subjects in comparison to patients with PTSD and healthy control subjects showed significantly a) higher fractional anisotropy (FA) in the left corticospinal tract and inferior fronto-occipital fasciculus than patients with PTSD, b) higher FA in the left inferior fronto-occipital-, right inferior- and right superior longitudinal fasciculi, c) higher FA in the forceps minor and d) higher volume of the left and right anterior insulae. Second, we show significant correlations between the FA in the forceps minor and the gray matter volume in the left and right anterior insulae. Third, the mean FA value in the forceps minor correlated negatively with symptom severity of PTSD and depression as well as trait anxiety, whereas the gray matter volume in the left anterior insula correlated negatively with symptom severity in PTSD. Our findings underline the importance of brain structures critically involved in emotion regulation and salience mapping. While previous studies associated these processes primarily to functional and task-based differences in brain activity, we argue that morphometrical white and gray matter differences could serve as targets in neuroscientifically-informed prevention and treatment interventions for PTSD.

PTSD-related neuroimaging abnormalities in brain function, structure, and biochemistry

Although approximately 90% of the U.S. population will experience a traumatic event within their lifetime, only a fraction of those traumatized individuals will develop posttraumatic stress disorder (PTSD). In fact, approximately 7 out of 100 people in the U.S. will be afflicted by this debilitating condition, which suggests there is substantial inter-individual variability in susceptibility to PTSD. This uncertainty regarding who is susceptible to PTSD necessitates a thorough understanding of the neurobiological processes that underlie PTSD development in order to build effective predictive models for the disorder. In turn, these predictive models may lead to the development of improved diagnostic markers, early intervention techniques, and targeted treatment approaches for PTSD. Prior research has characterized a fear learning and memory network, centered on the prefrontal cortex, hippocampus, and amygdala, that plays a key role in the pathology of PTSD. Importantly, changes in the function, structure, and biochemistry of this network appear to underlie the cognitive-affective dysfunction observed in PTSD. The current review discusses prior research that has demonstrated alterations in brain function, structure, and biochemistry associated with PTSD. Further, the potential for future research to address current gaps in our understanding of the neural processes that underlie the development of PTSD is discussed. Specifically, this review emphasizes the need for multimodal neuroimaging research and investigations into the acute effects of posttraumatic stress. The present review provides a framework to move the field towards a comprehensive neurobiological model of PTSD.

Effects of Recreational GHB Use and Multiple GHB-Induced Comas on Brain Structure and Impulsivity

BACKGROUND AND AIMS

The regular use of gamma-hydroxybutyrate acid (GHB) can induce GHB-induced comas. Other substance use disorders are associated with alterations in brain structure and impulsivity. Here we aim to investigate if these are also modulated by either regular GHB use or GHB-induced comas.

METHODS

In a sample of human males, structural and diffusion neuroimaging data were collected for 27 GHB users with ≥4 GHB-induced comas (GHB-Coma), 27 GHB users without GHB-induced comas (GHB-NoComa), and 27 polydrug users who never used GHB (No-GHB). The structural brain parameters were analyzed macroscopically using voxel-based morphometry and microscopically using tract-based spatial statistics (TBSS) and tractography. Impulsivity was assessed with the Barrat Impulsivity Scale.

RESULTS

In comparison to the other two groups, the GHB-Coma group showed a higher fractional anisotropy in the body of the corpus callosum and a lower mean diffusivity in the forceps minor (i.e., whole-brain TBSS analysis). No macrostructural differences nor microstructural differences, as assessed with tractography, were observed. The GHB-Coma group also reported higher impulsivity, which was more strongly associated with white matter volume and fractional anisotropy in tracts involved in impulse control (post-hoc analysis). GHB use per se was associated neither with differences in brain structure nor with impulsivity.

CONCLUSIONS

The results suggest that multiple GHB-induced comas, but not GHB use per se, are associated with microstructural alterations in white matter and with higher self-reported impulsivity, which in turn was associated with white matter tracts involved in impulse control.

Nervous and Endocrine System Dysfunction in Posttraumatic Stress Disorder: An Overview and Consideration of Sex as a Biological Variable

Decades of research into the biological mechanisms of posttraumatic stress disorder (PTSD) suggests that chronic activation of the stress response leads to long-lasting changes in the structure and function of the nervous and endocrine systems. While the prevalence of PTSD is twice as high in females as males, little is known about how sex differences in neuroendocrine systems may contribute to PTSD. In response to the paucity of research on sex-related mechanisms, the National Institutes of Health created a policy that asks researchers to consider sex as a biological variable. This review provides an overview of the current understanding of nervous and endocrine dysfunction in PTSD (e.g., neural circuitry, autonomic arousal, hormonal response), highlighting areas where the influence of sex has been characterized and where further research is needed. We also provide recommendations for using the sex-as-a-biological-variable policy to address specific gaps in PTSD neuroscience research.

White matter microstructural alterations in posttraumatic stress disorder: An ROI and whole-brain based meta-analysis

BACKGROUND

Posttraumatic stress disorder (PTSD) is a debilitating mental illness that is thought to be associated with brain white matter (WM) alterations. Individual diffusion tensor imaging (DTI) studies to date have reported inconsistent alterations in FA across different brain regions in patients with PTSD. Here, we aimed to investigate FA in PTSD using both region-of-interest (ROI)-based and whole-brain-based meta-analytic approaches.

OBJECTIVES

Individual ROI-based meta-analysis was carried out in each eligible white matter tract and seed-based D mapping (SDM) meta-analysis was conducted in the whole brain to identify the convergence of FA alterations in PTSD relative to controls.

RESULTS

Seventeen studies were included in ROI-based meta-analysis (≥ 3 studies were included for each ROI, N_PTSD ≥ 80 and N_control ≥ 103 per ROI). Fourteen studies with a total of 322 PTSD and 335 controls were included in whole-brain based meta-analysis. Both ROI and whole-brain meta-analyses showed that patients with PTSD have significantly higher FA in the inferior fronto-occipital fasciculus and lower FA in the genu of corpus callosum. Whole-brain meta-analyses also identified higher FA in the left inferior temporal gyrus and lower FA in the anterior cingulum and left corticospinal tract.

LIMITATIONS

A small number of studies were included in some ROI tracts. Thus the results should be interpreted with caution.

CONCLUSIONS

Our results suggest that PTSD patients have increased FA in areas related to visual processing, but decreased FA in anterior brain regions critical to cognition association and fear regulation.

Childhood maltreatment experiences are associated with altered diffusion in occipito-temporal white matter pathways

BACKGROUND

Childhood maltreatment may contribute to brain alterations in posttraumatic stress disorder (PTSD). We previously found that PTSD was associated with white matter compromise, or lower fractional anisotropy (FA), in the left inferior longitudinal fasciculus (ILF). In this study, including non-PTSD controls, we examined whether ILF FA was associated with maltreatment exposures, including those that meet DSM-IV criterion A (physical abuse, sexual abuse) and those that typically do not (emotional abuse, emotional neglect, physical neglect). We hypothesized that lower FA would be associated with PTSD diagnosis and with both categories of maltreatment.

METHODS

Ninety-three participants (51 female), ages 20-50, were enrolled, including 32 with lifetime DSM-IV PTSD, 27 trauma-exposed non-PTSD controls, and 34 healthy controls. Participants completed structured interviews, the Childhood Trauma Questionnaire (CTQ), and diffusion-weighted imaging (36 directions). Probabilistic tractography (using FreeSurfer's TRACULA) was used to assess diffusion metrics in the ILF.

RESULTS

Contrary to our hypothesis, there was no significant effect of diagnostic group on FA. In contrast, higher CTQ scores were significantly associated with lower FA in the ILF bilaterally. This association of maltreatment with lower FA remained statistically significant after controlling for diagnostic group, and it was significant for both criterion-A-type and noncriterion-A-type maltreatment categories.

CONCLUSIONS

This work contributes to a growing body of literature indicating that different forms of childhood maltreatment are associated with altered white matter microstructure in the ILF, an association pathway involved in integrating visual information from occipital regions with emotion processing functions of the anterior temporal lobe.

White matter integrity and functional predictors of response to repetitive transcranial magnetic stimulation for posttraumatic stress disorder and major depression

BACKGROUND

Recent evidence suggests that therapeutic repetitive transcranial magnetic stimulation (TMS) is an effective treatment for pharmacoresistant posttraumatic stress disorder (PTSD) and comorbid major depressive disorder (MDD). We recently demonstrated that response to 5 Hz TMS administered to the dorsolateral prefrontal cortex was predicted by functional connectivity of the medial prefrontal (MPFC) and subgenual anterior cingulate cortex (sgACC). This functionally-defined circuit is a novel target for treatment optimization research, however, our limited knowledge of the structural pathways that underlie this functional predisposition is a barrier to target engagement research.

METHODS

To investigate underlying structural elements of our previous functional connectivity findings, we submitted pre-TMS diffusion-weighted imaging data from 20 patients with PTSD and MDD to anatomically constrained tract-based probabilistic tractography (FreeSurfer's TRActs Constrained by UnderLying Anatomy). Averaged pathway fractional anisotropy (FA) was extracted from four frontal white matter tracts: the forceps minor, cingulum, anterior thalamic radiations (ATRs), and uncinate fasciculi. Tract FA statistics were treated as explanatory variables in backward regressions testing the relationship between tract integrity and functional connectivity coefficients from MPFC and sgACC predictors of symptom improvement after TMS.

RESULTS

FA in the ATRs was consistently associated with symptom improvement in PTSD and MDD (Bonferroni-corrected p < .05).

CONCLUSION

We found that structural characteristics of the ATR account for significant variance in individual-level functional predictors of post-TMS improvement. TMS optimization studies should target this circuit either in stand-alone or successive TMS stimulation protocols.

Improved gray matter surface based spatial statistics in neuroimaging studies

Neuroimaging often involves acquiring high-resolution anatomical images along with other low-resolution image modalities, like diffusion and functional magnetic resonance imaging. Performing gray matter statistics with low-resolution image modalities is a challenge due to registration artifacts and partial volume effects. Gray matter surface based spatial statistics (GS-BSS) has been shown to provide higher sensitivity using gray matter surfaces compared to that of skeletonization approach of gray matter based spatial statistics which is adapted from tract based spatial statistics in diffusion studies. In this study, we improve upon GS-BSS incorporating neurite orientation dispersion and density imaging (NODDI) based search (denoted N-GSBSS) by 1) enhancing metrics mapping from native space, 2) incorporating maximum orientation dispersion index (ODI) search along surface normal, and 3) proposing applicability to other modalities, such as functional MRI (fMRI). We evaluated the performance of N-GSBSS against three baseline pipelines: volume-based registration, FreeSurfer's surface registration and ciftify pipeline for fMRI and simulation studies. First, qualitative mean ODI results are shown for N-GSBSS with and without NODDI based search in comparison with ciftify pipeline. Second, we conducted one-sample t-tests on working memory activations in fMRI to show that the proposed method can aid in the analysis of low resolution fMRI data. Finally we performed a sensitivity test in a simulation study by varying percentage change of intensity values within a region of interest in gray matter probability maps. N-GSBSS showed higher sensitivity in the simulation test compared to the other methods capturing difference between the groups starting at 10% change in the intensity values. The computational time of N-GSBSS is 68 times faster than that of traditional surface-based or 86 times faster than that of ciftify pipeline analysis.

Cumulative childhood interpersonal trauma is associated with reduced cortical differentiation between threat and non-threat faces in posttraumatic stress disorder adults

OBJECTIVE

Posttraumatic stress disorder and childhood trauma frequently co-occur. Both are associated with abnormal neural responses to salient emotion stimuli. As childhood trauma is a risk factor for posttraumatic stress disorder, differentiating between their neurophysiological effects is necessary to elucidate the neural pathways by which childhood trauma exposure contributes to increased posttraumatic stress disorder risks.

METHODS

Face-specific N170 evoked response potentials for backward-masked (non-conscious) and conscious threat (fear, angry) and non-threat (happy) faces were measured in 77 adults (18-64 years old, 64% women, 78% right-handed) symptomatic for posttraumatic stress disorder. Differences in N170 peak amplitudes for fear-versus-happy and angry-versus-happy faces at bilateral temporo-occipital (T5, T6) sites were computed. The effect of cumulative exposure to childhood interpersonal trauma, other childhood trauma, adult trauma, depression and posttraumatic stress disorder symptom severity on the N170 response was assessed using hierarchical multiple regression analyses.

RESULTS

T5 N170 peak amplitudes for non-conscious fear-versus-happy faces were inversely related to cumulative childhood interpersonal trauma after accounting for socio-demographic, clinical symptom and other trauma factors. Posttraumatic stress disorder Avoidance was positively associated with N170 peak amplitudes for non-conscious fear-versus-happy faces, primarily due to reduced N170 responsivity to happy faces.

CONCLUSION

Childhood interpersonal trauma exposure is associated with reduced discrimination between fear and happy faces, while avoidance symptom severity is associated with dampened responsivity to automatically processed happy faces in posttraumatic stress disorder adults. Results are discussed in terms of the likely contributions of impaired threat discrimination and deficient reward processing during neural processing of salient emotion stimuli, to increased risks of posttraumatic stress disorder onset and chronicity in childhood interpersonal trauma-exposed adults.

White Matter Microstructure in Adolescents and Young Adults With Non-Suicidal Self-Injury

BACKGROUND

Non-suicidal self-injury (NSSI) is a growing public health concern that commonly begins in adolescence, and can persist into young adulthood. A promising approach for advancing our understanding of NSSI in youth is to examine white matter microstructure using diffusion magnetic resonance imaging (dMRI).

METHOD

The present study examined whole-brain group differences in structural connectivity (as measured by generalized fractional anisotropy [GFA]) between 28 female adolescents and young adults ages 13-21 years with NSSI and 22 age-matched healthy controls (HC). We also explored the association between clinical characteristics including NSSI severity and duration, impulsivity, emotion regulation and personality traits within the NSSI group and GFA of the uncinate fasciculus and cingulum.

RESULTS

Compared to the HC group, participants with NSSI had lower GFA in several white matter tracts, including the uncinate fasciculus, cingulum, bilateral superior and inferior longitudinal fasciculi, anterior thalamic radiation, callosal body, and corticospinal tract. When controlling for depressive symptoms, the NSSI group showed an association between NSSI duration (time since initiating NSSI behavior) and lower GFA in the left cingulum. Higher levels of attentional impulsivity were related to lower GFA in the left uncinate fasciculus within the NSSI group.

CONCLUSIONS

We found evidence suggesting widespread white matter microstructure deficits in adolescents and young adults with NSSI versus HC. We also report inverse associations between white matter integrity and clinical characteristics (duration of NSSI and attentional impulsivity). These white matter microstructural deficits may represent a possible neurobiologically-based vulnerability to developing maladaptive coping mechanisms, such as NSSI. Additionally, results suggest that this white matter disorganization may either worsen with prolonged engagement in NSSI or predict persistent NSSI; thereby highlighting the importance of early intervention targeting this behavior.

Repetitive transcranial magnetic stimulation in trauma-related conditions

Some of trauma-exposed individuals develop posttraumatic stress disorder (PTSD), an incapacitating psychiatric disorder that is characterized by intrusion, avoidance, negative changes in mood and cognition, and hyperarousal. A number of other trauma-related conditions are very frequently found in individuals with PTSD. Traumatic brain injury (TBI) is one of the most frequently observed trauma-related conditions that trauma-exposed individuals with PTSD may experience. TBI refers to transient or permanent brain dysfunction that results in a wide range of neurological, cognitive, and psychiatric symptoms. These trauma-related conditions significantly affect one's quality of life, leading to substantial disability and socioeconomic burden. As the prevalence of PTSD with comorbid TBI is increasing in the general population along with the rates of crimes and accidents, effective prevention and intervention strategies are necessitated. However, a definitive treatment for PTSD with comorbid TBI is still lacking, resulting in high rates of treatment resistance and chronicity. It is essential to investigate the neurobiological mechanisms and potential therapeutics of PTSD with comorbid TBI. Yet, a few repetitive transcranial magnetic stimulation (rTMS) studies have recently investigated therapeutic efficacy in treatment-resistant patients with PTSD and/or TBI. Thus, this article reviews rTMS studies in trauma-related conditions, mainly focusing on PTSD and PTSD with TBI as one of the comorbidities. The review focuses on the applications of rTMS in reducing PTSD symptoms with and without comorbidities based on differential parameters and effects of rTMS as well as concomitant clinical conditions. The section on PTSD with comorbidities focuses on TBI with neurological, cognitive, and psychiatric symptoms. Although there were some inconsistencies in the clinical outcomes and optimized parameters of rTMS applied in PTSD and TBI, low frequency stimulation over the hyperactive frontal regions and/or high frequency stimulation over the hypoactive frontal regions generally improved the clinical symptoms of PTSD and TBI. Lastly, the limitations of the rTMS studies in PTSD and TBI as well as potential directions for future research are discussed.

Diffusion Tensor Imaging Analysis of Mild Traumatic Brain Injury and Posttraumatic Stress Disorder

BACKGROUND

Debate exists over the extent to which dysfunctions arising from mild traumatic brain injury (mTBI) are distinct from posttraumatic stress disorder (PTSD).

METHODS

This study investigated 1) the white matter integrity of participants with either mTBI or PTSD, and 2) the relationship between white matter integrity and postconcussive syndrome. The sample comprised 110 civilians (mTBI group = 40; PTSD group = 32; age- and sex-matched trauma-exposed control subjects = 38) recruited from community advertising. Indicators of white matter abnormalities were fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity. PTSD symptoms were indexed by the Clinician-Administered PTSD Scale, and postconcussive symptoms were assessed using the Somatic and Psychological Health Report measure.

RESULTS

Fractional anisotropy was reduced in mTBI participants in the corpus callosum, tracts of the brainstem, projection fibers, association fibers, and limbic fibers compared with both PTSD and trauma-exposed control subjects. This decrease in fractional anisotropy was observed in the context of concurrent changes in radial diffusivity, axial diffusivity, and mean diffusivity. Postconcussive symptoms were largely explained by PTSD severity rather than by changes in brain white matter. mTBI appears to be characterized by distinct reductions in white matter integrity, and this cannot be attributed to PTSD.

CONCLUSIONS

PTSD symptoms appear to be more strongly associated with postconcussive syndrome than with white matter compromise. These findings extend epidemiological evidence of the relative associations of PTSD and mTBI with postconcussive syndrome.

Structural Connectivity of the Posterior Cingulum Is Related to Reexperiencing Symptoms in Posttraumatic Stress Disorder

Posttraumatic stress disorder is a heterogeneous disorder with disturbances in hyperarousal or avoidance behaviors and intrusive or reexperiencing thoughts. The uncinate fasciculus and cingulum bundle are white matter pathways implicated in stress and trauma pathophysiology, yet their structural integrity related to posttraumatic stress disorder symptom domains is yet to be understood. Forty-four trauma-exposed young adults underwent structural and diffusion-weighted magnetic resonance imaging. Stress and trauma exposure indices and severity of posttraumatic stress disorder symptoms were collected and used to predict current integrity of the uncinate fasciculus and cingulum bundle. Severity of reexperiencing posttraumatic stress disorder symptoms was significantly related to increased fractional anisotropy (r = .469 p < .001) and decreased mean diffusivity (r =  −.373, p = .013) of the right posterior cingulum bundle. No other findings emerged with respect to stress exposure or of hyperarousal (p’s > 0.05) or avoidance (p’s > 0.2) posttraumatic stress disorder symptoms. The posterior cingulum connects medial temporal lobe structures with visual areas in the occipital lobe and has been implicated in visual memory and self-referential thought. Increased structural connectivity along this pathway may therefore explain the emergence of reexperiencing posttraumatic stress disorder symptoms. This along with the lack of results with respect to stress exposure suggests that structural aberrations in white matter pathways are more strongly linked with the actual experience of stress-related psychological symptoms than just exposure to stress.

The cingulum bundle: Anatomy, function, and dysfunction

The cingulum bundle is a prominent white matter tract that interconnects frontal, parietal, and medial temporal sites, while also linking subcortical nuclei to the cingulate gyrus. Despite its apparent continuity, the cingulum's composition continually changes as fibres join and leave the bundle. To help understand its complex structure, this review begins with detailed, comparative descriptions of the multiple connections comprising the cingulum bundle. Next, the impact of cingulum bundle damage in rats, monkeys, and humans is analysed. Despite causing extensive anatomical disconnections, cingulum bundle lesions typically produce only mild deficits, highlighting the importance of parallel pathways and the distributed nature of its various functions. Meanwhile, non-invasive imaging implicates the cingulum bundle in executive control, emotion, pain (dorsal cingulum), and episodic memory (parahippocampal cingulum), while clinical studies reveal cingulum abnormalities in numerous conditions, including schizophrenia, depression, post-traumatic stress disorder, obsessive compulsive disorder, autism spectrum disorder, Mild Cognitive Impairment, and Alzheimer's disease. Understanding the seemingly diverse contributions of the cingulum will require better ways of isolating pathways within this highly complex tract.

Cerebral White Matter Changes in Young Healthy Individuals With High Trait Anxiety: A Tract-Based Spatial Statistics Study

Background: Abnormalities in prespecified and empirical white matter tracts in young patients with anxiety-related disorders have been reported in some diffusion tensor imaging (DTI) studies. However, with few literatures examining the association between the integrity of whole brain white matter and trait anxiety levels in the non-clinical populations, whether white matter changes arise in young healthy individuals with high trait anxiety remains unknown.

Methods: We examined whole brain white matter alterations in young healthy individuals with high anxiety but without history of neurological or psychiatric disorders via DTI technology. Group comparison of tract-based spatial statistics (TBSS) was performed to investigate the microstructural diffusion alterations in 38 high anxious subjects in comparison with 34 low anxious subjects matched with age, gender, and degree of education. These analyses controlled for depression to establish specificity to trait anxiety.

Results: Young healthy subjects with high trait anxiety had significantly decreased fractional anisotropy (FA) values in multiple clusters, including corona radiate (CR), anterior thalamic radiation (ATR), inferior fronto-occipital fasciculus (IFOF), bilaterally, body, genu, and splenium of corpus callosum (CC) and forceps minor, compared with low trait anxious subjects. For the abnormal FA regions, the other diffusion metrics were also altered slightly.

Conclusions: Non-clinical individuals with high anxiety already have white matter alterations in the thalamus-cortical circuit and some emotion-related areas that were widely reported in anxiety-related disorders. The altered white matter may be a vulnerability marker in individuals at high risk of clinical anxiety. These findings can deepen our understanding of the pathological mechanism of anxiety and further support the need for preventive interventions in high anxiety individuals.

Altered White Matter Diffusivity of the Cingulum Angular Bundle in Posttraumatic Stress Disorder

Purpose of the Study

Prior studies showed posttraumatic stress disorder (PTSD)-related alterations in white matter integrity, but most of these studies have used region-based approaches. We address this limitation by investigating the relationship between PTSD severity and fractional anisotropy (FA) using a tract-based approach.

Procedures

Structural and diffusion magnetic resonance imaging were acquired from 67 combat-exposed US Veterans and processed using FSL/FreeSurfer TRActs Constrained by UnderLying Anatomy. Partial correlations were conducted between PTSD severity and FA of the cingulum and uncinate fasciculi covarying for age, sex, and head motion.

Results

Only FA of the left cingulum angular bundle (CAB) was positively correlated with PTSD symptom severity (r = 0.433, p = 0.001, df = 57) and remained significant after Bonferroni correction.

Conclusions

This finding may imply greater organization of the CAB with increasing PTSD severity. The CAB connects directly to the cingulate cortex and the hippocampal subiculum, critical nodes of the default mode network, as well as being implicated in neurodegeneration pathology, decision-making, and executive functions, which may help explain previously shown alterations in this network in PTSD.

Message of the Paper

Further study of white matter tract integrity in PTSD is warranted, particularly to investigate whether the CAB connections with both higher-order cognitive functioning and emotion processing regions contribute to the pathophysiology and comorbidity of PTSD.

Structural white matter changes in adults and children with posttraumatic stress disorder: A systematic review and meta-analysis

White matter plasticity occurs throughout life due to learning and can be a protective factor against as well as a vulnerability factor for the development of mental disorders. In this systematic review we summarize findings on structural white matter changes in children and adults with posttraumatic stress disorder (PTSD) and relate them to theoretical accounts of the pathophysiology of PTSD with a focus on the disturbed processing of contexts and associated problems in emotional and cognitive processing and PTSD symptomatology. We particularly examine studies reporting fractional anisotropy (FA) measured with diffusion tensor imaging (DTI). We further subdivided the studies in adult-onset PTSD with traumatic experience in adulthood, adult-onset PTSD with traumatic experience in childhood and children with PTSD. We included 30 studies comprising almost 1700 participants with 450 adults and 300 children suffering from PTSD. Our systematic review showed that for children with PTSD and adult-onset PTSD with childhood trauma, a decrease in FA in the corpus collosum, most prominently in the anterior and posterior midbody, the isthmus and splenium were reported. For adult-onset PTSD with traumatic experience in adulthood, changes in FA in the anterior and posterior part of the cingulum, the superior longitudinal fasciculus and frontal regions were found. Using GingerAle, we also performed a coordinate-based meta-analysis of 14 studies of adult-onset PTSD with traumatic experience in adulthood and did not find any significant clusters. Our results suggest that changes in white matter microstructure vary depending on traumatic experience and are associated with changes in brain circuits related to the processing of contexts. Finally, we present methodological considerations for future studies.