PTSD REMISSION AFTER PROLONGED EXPOSURE TREATMENT IS ASSOCIATED WITH ANTERIOR CINGULATE CORTEX THINNING AND VOLUME REDUCTION

Distinct saliva DNA methylation profiles in relation to treatment outcome in youth with posttraumatic stress disorder

In youth with posttraumatic stress disorder (PTSD) non-response rates after treatment are often high. Epigenetic mechanisms such as DNA methylation (DNAm) have previously been linked to PTSD pathogenesis, additionally DNAm may affect response to (psychological) therapies. Besides investigating the direct link between DNAm and treatment response, it might be helpful to investigate the link between DNAm and previously associated biological mechanisms with treatment outcome. Thereby gaining a deeper molecular understanding of how psychotherapy (reflecting a change in the environment) relates to epigenetic changes and the adaptability of individuals. To date, limited research is done in clinical samples and no studies have been conducted in youth. Therefore we conducted a study in a Dutch cohort of youth with and without PTSD (n = 87, age 8-18 years). We examined the cross-sectional and longitudinal changes of saliva-based genome-wide DNA methylation (DNAm) levels, and salivary cortisol secretion. The last might reflect possible abbreviations on the hypothalamic-pituitary- adrenal (HPA) axis. The HPA-axis is previously linked to DNAm and the development and recovery of PTSD. Youth were treated with 8 sessions of either Eye Movement Reprocessing Therapy (EMDR) or Trauma Focused Cognitive behavioral Therapy (TF-CBT). Our epigenome wide approach showed distinct methylation between treatment responders and non-responders on C18orf63 gene post-treatment. This genomic region is related to the PAX5 gene, involved in neurodevelopment and inflammation response. Additionally, our targeted approach indicated that there were longitudinal DNAm changes in successfully treated youth at the CRHR2 gene. Methylation at this gene was further correlated with cortisol secretion pre- and post-treatment. Awaiting replication, findings of this first study in youth point to molecular pathways involved in stress response and neuroplasticity to be associated with treatment response.

Findings of PTSD-specific deficits in default mode network strength following a mild experimental stressor

Reductions in default mode (DMN) connectivity strength have been reported in posttraumatic stress disorder (PTSD). However, the specificity of DMN connectivity deficits in PTSD compared to major depressive disorder (MDD), and the sensitivity of these alterations to acute stressors are not yet known. 52 participants with a primary diagnosis of PTSD (n = 28) or MDD (n = 24) completed resting-state functional magnetic resonance imaging immediately before and after a mild affective stressor. A 2 × 2 design was conducted to determine the effects of group, stress, and group*stress on DMN connectivity strength. Exploratory analyses were completed to identify the brain region(s) underlying the DMN alterations. There was significant group*stress interaction (p = 0.03), reflecting stress-induced reduction in DMN strength in PTSD (p = 0.02), but not MDD (p = 0.50). Nodal exploration of connectivity strength in the DMN identified regions of the ventromedial prefrontal cortex and the precuneus potentially contributing to DMN connectivity deficits. The findings indicate the possibility of distinct, disease-specific, patterns of connectivity strength reduction in the DMN in PTSD, especially following an experimental stressor. The identified dynamic shift in functional connectivity, which was perhaps induced by the stressor task, underscores the potential utility of the DMN connectivity and raises the question whether these disruptions may be inversely affected by antidepressants known to treat both MDD and PTSD psychopathology.

Gray matter differences in adults and children with posttraumatic stress disorder: A systematic review and meta-analysis of 113 studies and 11 meta-analyses

BACKGROUND

In this systematic review and meta-analysis, we aimed to provide a comprehensive overview of gray matter alterations of adult- and underage patients with posttraumatic stress disorder (PTSD) in comparison to healthy trauma-exposed (TC) and non-exposed (HC) individuals.

METHODS

We subdivided our groups into patients with PTSD after trauma exposure in adulthood (aa) or childhood (ac) as well as children with PTSD (cc). We identified 113 studies, including 6.800 participants in our review, which we divided into studies focusing on whole-brain and region-of-interest (ROI) analysis. We performed a coordinate-based meta-analysis on 14 studies in the group of aa-PTSD.

RESULTS

We and found lower gray matter volume in patients with PTSD (aa) in the medial frontal gyrus (PTSD<HC/TC) and Culmen/posterior cingulate cortex (PTSD<TC). Results from ROI-based studies mainly show alterations for patients with PTSD in the prefrontal cortex, hippocampus, anterior cingulate cortex, insula, corpus callosum, and amygdala.

LIMITATIONS

Due to a limited number of studies reporting whole-brain results, the meta-analyses could only be performed in one subgroup and within this subgroup for a limited number of studies.

CONCLUSIONS

Our results are in line with psychobiological models of PTSD that associate the identified regions with brain circuits involved in context processing, threat detection and emotion regulation.

Adjunct treatment with ketamine enhances the therapeutic effects of extinction learning after chronic unpredictable stress

Post-traumatic stress disorder (PTSD) is a debilitating illness characterized by dysfunction in the medial prefrontal cortex (mPFC). Although both pharmacological and cognitive behavioral interventions have shown some promise at alleviating symptoms, high attrition and persistence of treatment-resistant symptoms pose significant challenges that remain unresolved. Specifically, prolonged exposure therapy, a gold standard intervention to treat PTSD, has high dropout rates resulting in many patients receiving less than a fully effective course of treatment. Administering pharmacological treatments together with behavioral psychotherapies like prolonged exposure may offer an important avenue for enhancing therapeutic efficacy sooner, thus reducing the duration of treatment and mitigating the impact of attrition. In this study, using extinction learning as a rat model of exposure therapy, we hypothesized that administering ketamine as an adjunct treatment together with extinction will enhance the efficacy of extinction in reversing stress-induced deficits in set shifting, a measure of cognitive flexibility. Results showed that combining a sub-effective dose of ketamine with a shortened, sub-effective extinction protocol fully reversed stress-induced cognitive set-shifting deficits in both male and female rats. These effects may be due to shared molecular mechanisms between extinction and ketamine, such as increased neuronal plasticity in common circuitry (e.g., hippocampus-mPFC), or increased BDNF signaling. This work suggests that fast-acting drugs, such as ketamine, can be effectively used in combination with behavioral interventions to reduce treatment duration and potentially mitigate the impact of attrition. Future work is needed to delineate other pharmacotherapies that may complement the effects of extinction via shared or independent mechanisms.

Mapping structural covariance networks in children and adolescents with post-traumatic stress disorder after earthquake

For children and adolescents, there is a high risk of developing post-traumatic stress disorder (PTSD) after suffering from catastrophic events. Previous studies have identified brain functionally and subcortical brain volumes structurally abnormalities in this population. However, up till now, researches exploring alterations of regional cortical thickness (CTh) and brain interregional structural covariance networks (SCNs) are scarce. In this cross-sectional study, CTh measures are derived from 3-Tesla Tl-weighted MRI imaging data in a well-characterized combined group of children and adolescents with PTSD after an earthquake (N = 35) and a traumatized healthy control group (N = 24). By using surface-based morphometry (SBM) techniques, the regional CTh analysis was conducted. To map interregional SCNs derived from CTh, twenty-five altered brain regions reported in the PTSD population were selected as seeds. Whole-brain SBM analysis discovered a significant thickness reduction in the left medial orbitofrontal cortex for the subjects with PTSD. Similarly, analysis of SCNs associated with "seed" regions primarily located in default mode network (DMN), midline cortex structures, motor cortex, auditory association cortex, limbic system, and visual cortex demonstrated that children and adolescents with PTSD are associated with altered structural covariance with six key regions. This study provides evidence for distinct CTh correlates of PTSD that are present across children and adolescents, suggesting that brain cortical abnormalities related to trauma exposure are present in this population, probably by driving specific symptom clusters associated with disrupted extinction recall mechanisms for fear, episodic memory network and visuospatial attention.

Structural brain features signaling trauma, PTSD, or resilience? A systematic exploration

BACKGROUND

Studies have searched for neurobiological markers of trauma exposure, posttraumatic stress disorder (PTSD) diagnosis, and resilience to trauma to identify therapeutic targets for PTSD. Despite some promising results, findings are inconsistent.

AIMS

The present study adopted a data-driven approach to systematically explore whether structural brain markers of trauma, PTSD, or resilience emerge when all are explored.

MATERIALS & METHODS

Differences between clusters in the proportion of PTSD, healthy controls (HC), and trauma-exposed healthy controls (TEHC) served to indicate the presence of PTSD, trauma, and resilience markers, respectively. A total of 129 individuals, including 46 with PTSD, 49 TEHCs, and 34 HCs not exposed to trauma were scanned. Volumes, cortical thickness, and surface areas of interest were obtained from T1 structural MRI and used to identify data-driven clusters.

RESULTS

Two clusters were identified, differing in the proportion of TEHCs but not of PTSDs or HCs. The cluster with the higher proportion of TEHCs, referred to as the resilience cluster, was characterized by higher volume in brain regions implicated in trauma exposure, especially the thalamus and rostral middle frontal gyrus. Cross-validation established the robustness and consistency of the identified clusters.

DISCUSSION & CONCLUSION

Findings support the existence of structural brain markers of resilience.

Neural changes following equine-assisted therapy for posttraumatic stress disorder: A longitudinal multimodal imaging study

Background

While effective treatments for posttraumatic stress disorder (PTSD) exist, many individuals, including military personnel and veterans fail to respond to them. Equine‐assisted therapy (EAT), a novel PTSD treatment, may complement existing PTSD interventions. This study employs longitudinal neuro‐imaging, including structural magnetic resonance imaging (sMRI), resting state‐fMRI (rs‐fMRI), and diffusion tensor imaging (DTI), to determine mechanisms and predictors of EAT outcomes for PTSD.

Method

Nineteen veterans with PTSD completed eight weekly group sessions of EAT undergoing multimodal MRI assessments before and after treatment. Clinical assessments were conducted at baseline, post‐treatment and at 3‐month follow‐up.

Results

At post‐treatment patients showed a significant increase in caudate functional connectivity (FC) and reduction in the gray matter density of the thalamus and the caudate. The increase of caudate FC was positively associated with clinical improvement seen immediately at post‐treatment and at 3‐month follow‐up. In addition, higher baseline caudate FC was associated with greater PTSD symptom reduction post‐treatment.

Conclusions

This exploratory study is the first to demonstrate that EAT can affect functional and structural changes in the brains of patients with PTSD. The findings suggest that EAT may target reward circuitry responsiveness and produce a caudate pruning effect from pre‐ to post‐treatment.

Trauma-focused psychotherapy response in youth with posttraumatic stress disorder is associated with changes in insula volume

Randomized controlled trials have shown efficacy of trauma-focused psychotherapies in youth with posttraumatic stress disorder (PTSD), but little is known about the relationship between treatment response and alternations in brain structures associated with PTSD. In this study, we longitudinally examined the association between treatment response and pre-to posttreatment changes in structural magnetic resonance imaging (MRI) scans using a voxel-based morphometry approach. We analyzed MRI scans of 35 patients (ages 8-18 years, 21 female) with PTSD (80%) or partial PTSD (20%) before and after eight weekly sessions of trauma-focused psychotherapy. PTSD severity was assessed longitudinally using the Clinician-Administered PTSD scale for Children and Adolescents to divide participants into responders and non-responders. Group by time interaction analysis showed significant differences in grey-matter volume in the bilateral insula due to volume reductions over time in non-responders compared to responders. Despite the significant group by time interaction, there were no significant group differences at baseline or follow-up. As typical development is associated with insula volume increase, these longitudinal MRI findings suggest that treatment non-response is associated with atypical neurodevelopment of the insula, which may underlie persistence of PTSD in youth. The absence of structural MRI changes in treatment responders, while in need of replication, suggest that successful trauma-focused psychotherapy may not directly normalize brain abnormalities associated with PTSD.

Does trauma-focused psychotherapy change the brain? A systematic review of neural correlates of therapeutic gains in PTSD

BACKGROUND

Meta-analytic results indicate that posttraumatic stress disorder (PTSD) is associated with hypoactivation of the medial prefrontal cortex (mPFC), hyperactivation of the amygdala, and volume reductions of the hippocampus. Effective psychotherapeutic treatments were hypothesized to normalize these neural patterns via upregulation of prefrontal structures, which in turn downregulate limbic regions.

OBJECTIVE

To gain a sound understanding of the effects of successful psychotherapy on the brain, neural changes from pre- to post-treatment in PTSD patients will be aggregated.

METHOD

A systematic literature search identified 24 original studies employing structural or functional MRI measurements both before and after treatment of patients diagnosed with PTSD.

RESULTS

In conjunction, the review returned little evidence of an activation increase in the mPFC/rostral anterior cingulate cortex (rACC) following successful treatment. Five out of 12 studies observed such an increase (especially during emotion processing tasks), albeit in partially non-overlapping brain regions. Conversely, neither the putative related activation decrease in the amygdala nor volumetric changes or altered activation during the resting state could be convincingly established.

CONCLUSION

Successful psychological treatments might potentially work via upregulation of the mPFC, which thus may be involved in symptom reduction. However, the role of the amygdala in recovery from PTSD remains unclear. There is currently no indication that the various PTSD treatment approaches employed by the reviewed studies differ regarding their action mechanisms, but further research on this topic is needed.

EMDR Versus Treatment-as-Usual in Patients With Chronic Non-Malignant Pain: A Randomized Controlled Pilot Study

In recent years, different studies have observed a strong association between chronic pain (CP) and psychological trauma. Therefore, a trauma-focused psychotherapy, such as eye movement desensitization and reprocessing (EMDR), could be an innovative treatment option. The aim of this pilot study was to assess whether a specific EMDR protocol for CP leads to (a) a reduction in pain intensity, (b) an improvement in anxiety and depressive symptoms, and (c) an improvement in quality of life. 28 CP patients were randomly assigned to EMDR + treatment as usual (TAU; n = 14) or to TAU alone (n = 14). Patients in the EMDR group received 12 psychotherapeutic sessions of 90 minutes over 3 months. Pain intensity was measured using the Visual Analog Scale and the Pain Disability index, quality of life using the EQ-5D-5L, and anxiety and depressive symptoms using the Hamilton Anxiety and Depression Scale. Measures were taken for both conditions at pre- and post-treatment, and a follow-up in the EMDR condition was taken at 3 months post-treatment. Patients in the EMDR group showed significantly reduced pain intensity and improved quality of life and anxiety and depressive symptoms compared to TAU alone at post-treatment. Improvements were largely maintained at 3-month follow-up. This study suggests that EMDR may be an effective and safe psychological intervention to be used within the multidisciplinary treatment plan of patients with CP.

Diagnostic and Predictive Neuroimaging Biomarkers for Posttraumatic Stress Disorder

BACKGROUND

Comorbidity between posttraumatic stress disorder (PTSD) and major depressive disorder (MDD) has been commonly overlooked by studies examining resting-state functional connectivity patterns in PTSD. The current study used a data-driven approach to identify resting-state functional connectivity biomarkers to 1) differentiate individuals with PTSD (with or without MDD) from trauma-exposed healthy control subjects (TEHCs), 2) compare individuals with PTSD alone with those with comorbid PTSD+MDD, and 3) explore the clinical utility of the identified biomarkers by testing their associations with clinical symptoms and treatment response.

METHODS

Resting-state magnetic resonance images were obtained from 51 individuals with PTSD alone, 52 individuals with PTSD+MDD, and 76 TEHCs. Of the 103 individuals with PTSD, 55 were enrolled in prolonged exposure treatment. A support vector machine model was used to identify resting-state functional connectivity biomarkers differentiating individuals with PTSD (with or without MDD) from TEHCs and differentiating individuals with PTSD alone from those with PTSD+MDD. The associations between the identified features and symptomatology were tested with Pearson correlations.

RESULTS

The support vector machine model achieved 70.6% accuracy in discriminating between individuals with PTSD and TEHCs and achieved 76.7% accuracy in discriminating between individuals with PTSD alone and those with PTSD+MDD for out-of-sample prediction. Within-network connectivity in the executive control network, prefrontal network, and salience network discriminated individuals with PTSD from TEHCs. The basal ganglia network played an important role in differentiating individuals with PTSD alone from those with PTSD+MDD. PTSD scores were inversely correlated with within-executive control network connectivity (p < .001), and executive control network connectivity was positively correlated with treatment response (p < .001).

CONCLUSIONS

Results suggest that unique brain-based abnormalities differentiate individuals with PTSD from TEHCs, differentiate individuals with PTSD from those with PTSD+MDD, and demonstrate clinical utility in predicting levels of symptomatology and treatment response.

Individual prediction of psychotherapy outcome in posttraumatic stress disorder using neuroimaging data

Trauma-focused psychotherapy is the first-line treatment for posttraumatic stress disorder (PTSD) but 30-50% of patients do not benefit sufficiently. We investigated whether structural and resting-state functional magnetic resonance imaging (MRI/rs-fMRI) data could distinguish between treatment responders and non-responders on the group and individual level. Forty-four male veterans with PTSD underwent baseline scanning followed by trauma-focused psychotherapy. Voxel-wise gray matter volumes were extracted from the structural MRI data and resting-state networks (RSNs) were calculated from rs-fMRI data using independent component analysis. Data were used to detect differences between responders and non-responders on the group level using permutation testing, and the single-subject level using Gaussian process classification with cross-validation. A RSN centered on the bilateral superior frontal gyrus differed between responders and non-responder groups (P_FWE < 0.05) while a RSN centered on the pre-supplementary motor area distinguished between responders and non-responders on an individual-level with 81.4% accuracy (P < 0.001, 84.8% sensitivity, 78% specificity and AUC of 0.93). No significant single-subject classification or group differences were observed for gray matter volume. This proof-of-concept study demonstrates the feasibility of using rs-fMRI to develop neuroimaging biomarkers for treatment response, which could enable personalized treatment of patients with PTSD.

Theoretical Background and Clinical Aspects of the Use of EMDR in Patients With Bipolar Disorder

Bipolar disorder (BD) is associated with a lifelong episodic course of severe mood and behavioral disturbance. In last decades treatment improved with numerous pharmacological and psychosocial treatments; however, subsequent mood episode rates are still high and possible risk factors for subsequent mood episodes are not sufficiently addressed. Of note, childhood trauma and stressful life events represent significant, under-recognized, and often neglected environmental risk factors in the etiology and course of BD. Here, we summarize the evidence of eye movement desensitization and reprocessing (EMDR) therapy in BD with posttraumatic stress disorder (PTSD) or life traumatic events. So far, one case report study and one pilot randomized controlled trial (RCT) have been published suggesting positive effect of EMDR therapy in BD. Currently, two larger further RCTs are ongoing to increase scientific evidence of the use of EMDR therapy in this indication, especially with a focus on its effect on relapse prevention. In addition, a functional neuroimaging case report of a bipolar subject versus 30 healthy controls showed first evidence that EMDR might modulate the default mode network. These preliminary results suggest that EMDR could be a promising and safe psychotherapeutic approach for the add-on treatment of bipolar subjects, but confirmative large RCT are needed, with two currently being conducted.

Magnetic resonance imaging predictors of psychotherapy treatment response in post-traumatic stress disorder: A role for the salience network

The earliest neuroimaging studies in post-traumatic stress disorder (PTSD) utilized positron emission tomography (PET) to examine the brain's response to glucocorticoid administration given predominant neurobiological models of the stress response focusing on that neuroendocrine system. This work revealed that the anterior cingulate cortex and amygdala, which is now considered part of the salience network, play a role in treatment response, and set the stage for subsequent magnetic resonance (MR) imaging studies focused on understanding the role of the salience network in the neurobiology of treatment response in PTSD. This selective review discusses magnetic resonance (MR) imaging studies that have been used to predict treatment response to cognitive-behavioral therapy (CBT) or prolonged exposure (PE) in PTSD, which have demonstrated abnormalities in processing involving the salience network, including the amygdala, anterior cingulate cortex and insula. Increased attention to environmental cues may signal alarm resulting in hypervigilance and overactive action-monitoring for the detection of threatening stimuli and an inability to integrate concomitant emotional and sensory functions in PTSD. Successful psychotherapy treatment response in PTSD appears to involve the ability to downregulate amygdala activity to trauma-related stimuli through improved regulation of attention by the anterior cingulate cortex and concomitant internal emotional states mediated by the insula. In addition, the ability to better modulate (normalize) the salience network following psychotherapy in PTSD may be associated with better crosstalk between untargeted inner thought (i.e., task-negative network) and the ability to focus attention on stimulus-dependent demands (i.e., task positive network).

A Rodent Model of Exposure Therapy: The Use of Fear Extinction as a Therapeutic Intervention for PTSD

The symptoms of post-traumatic stress disorder (PTSD) include cognitive impairment related to medial prefrontal cortical dysfunction. Indeed, a deficit of cognitive flexibility, i.e., an inability to modify previously learned thoughts and behaviors based on changes in the environment, may underlie many of the other symptoms of PTSD, such as changes in mood, hyper-arousal, intrusive thoughts, exaggerated and over-generalized fear, and avoidance behavior. Cognitive-behavioral therapies target the cognitive dysfunction observed in PTSD patients, training them to recalibrate stress-related perceptions, interpretations and responses. Preclinically, the extinction of conditioned fear bears resemblance to one form of cognitive therapy, exposure therapy, whereby an individual learns, through repeated exposure to a fear-provoking stimulus in a safe environment, that the stimulus no longer signals imminent threat, and their fear response is suppressed. In this review article, we highlight recent findings from our lab using fear extinction as a preclinical model of exposure therapy in rodents exposed to chronic unpredictable stress (CUS). We specifically focus on the therapeutic effects of extinction on stress-compromised set-shifting as a measure of cognitive flexibility, and active vs. passive coping behavior as a measure of avoidance. Finally, we discuss mechanisms involving activity and plasticity in the medial prefrontal cortex (mPFC) necessary for the therapeutic effects of extinction on cognitive flexibility and active coping.

Neuroscience Informed Prolonged Exposure Practice: Increasing Efficiency and Efficacy Through Mechanisms

Prolonged exposure (PE) is an empirically supported efficacious treatment for posttraumatic stress disorder (PTSD). In this focused review, we briefly review the neurobiological networks in PTSD relevant to PE, discuss the theoretical basis of PE, review the neurobiological mechanisms underlying the effectiveness of PE and identify the enhancements that can be applied to increase treatment response and retention. Based on the reviewed studies, it is clear that PTSD results in disrupted network of interconnected regions, and PE has been shown to increase the connectivity within and between these regions. Successful extinction recall in PE is related to increased functional coherence between the ventromedial prefrontal cortex (vmPFC), amygdala and the hippocampus. Increased connectivity within the dorsolateral PFC (dlPFC) following PE is associated with more effective downregulation of emotional responses in stressful situations. Pre-existing neural connectivity also in some cases predicts response to exposure treatment. We consider various enhancements that have been used with PE, including serotonin reuptake inhibitors (SSRIs), D-cycloserine (DCS), allopregnanolone (ALLO) and propranolol, repetitive transcranial magnetic stimulation (rTMS), oxytocin and MDMA. Given that neural connectivity appears to be crucial in mechanisms of action of PE, rTMS is a logical target for further research as an enhancement of PE. Additionally, exploring the effectiveness and mechanisms of action of oxytocin and MDMA in conjunction with PE may lead to improvement in treatment engagement and retention.

Exposure-based therapy changes amygdala and hippocampus resting-state functional connectivity in patients with posttraumatic stress disorder

BACKGROUND

Recent research suggests that posttraumatic stress disorder (PTSD) is associated with altered amygdala and hippocampal resting-state functional connectivity (rsFC). However, less research has examined whether Prolonged Exposure (PE), a first line exposure-based treatment for PTSD, has the potential to alter resting state neural networks.

METHODS

A total of 24 patients with PTSD and 26 matched trauma-exposed healthy controls (TEHCs) underwent resting-state functional magnetic resonance imaging (fMRI) at baseline. PTSD patients were scanned a second time after completing 10-session PE in which patients narrated a detailed trauma account (imaginal exposure) and confronted trauma reminders (in vivo exposure) to extinguish trauma-related fear responses. TEHC were scanned again following a 10-week waiting period. Seed regions of interest (ROIs) included centromedial amygdala (CMA), basolateral amygdala (BLA), and the hippocampus.

RESULTS

Post- versus pretreatment comparisons indicated increased rsFC of the BLA and CMA with the orbitofrontal cortex (OFC), and hippocampus-medial prefrontal cortex (mPFC) among patients with PTSD, but not among TEHC participants.

CONCLUSIONS

Enhanced amygdala and hippocampus rsFC with prefrontal cortical regions following PE could underlie improved capacity for inhibition and re-evaluation of threat, and heightened memory encoding and retrieval ability, respectively. These findings encourage further investigation of this circuitry as a therapeutic target in PTSD.

Brain Structural Covariance Network Topology in Remitted Posttraumatic Stress Disorder

Posttraumatic stress disorder (PTSD) is a prevalent, chronic disorder with high psychiatric morbidity; however, a substantial portion of affected individuals experience remission after onset. Alterations in brain network topology derived from cortical thickness correlations are associated with PTSD, but the effects of remitted symptoms on network topology remain essentially unexplored. In this cross-sectional study, US military veterans (N = 317) were partitioned into three diagnostic groups, current PTSD (CURR-PTSD, N = 101), remitted PTSD with lifetime but no current PTSD (REMIT-PTSD, N = 35), and trauma-exposed controls (CONTROL, n = 181). Cortical thickness was assessed for 148 cortical regions (nodes) and suprathreshold interregional partial correlations across subjects constituted connections (edges) in each group. Four centrality measures were compared with characterize between-group differences. The REMIT-PTSD and CONTROL groups showed greater centrality in left frontal pole than the CURR-PTSD group. The REMIT-PTSD group showed greater centrality in right subcallosal gyrus than the other two groups. Both REMIT-PTSD and CURR-PTSD groups showed greater centrality in right superior frontal sulcus than CONTROL group. The centrality in right subcallosal gyrus, left frontal pole, and right superior frontal sulcus may play a role in remission, current symptoms, and PTSD history, respectively. The network centrality changes in critical brain regions and structural networks are associated with remitted PTSD, which typically coincides with enhanced functional behaviors, better emotion regulation, and improved cognitive processing. These brain regions and associated networks may be candidates for developing novel therapies for PTSD. Longitudinal work is needed to characterize vulnerability to chronic PTSD, and resilience to unremitting PTSD.

Sex Differences in Trauma-Related Psychopathology: a Critical Review of Neuroimaging Literature (2014-2017)

PURPOSE OF REVIEW

Sex differences in the epidemiology and clinical presentation of trauma-related psychopathology have long been documented. Multiple underlying mechanisms have been examined, both psychosocial and biological. Among the most promising biological mechanisms are neural substrates of trauma-related psychopathology that have been uncovered in recent years.

RECENT FINDINGS

Neuroimaging studies of sex-related heterogeneity published over the past 3 years (2014-2017) demonstrate an interaction between sex and type, timing, and load of trauma exposure. These studies suggest that, for males, early trauma exposure may involve a loss of gray matter in the limbic system, including the prefrontal cortex (PFC), amygdala, and hippocampus, and an over-activity and increased connectivity of salience hubs, and particularly dorsal anterior cingulate cortex (dACC). For females, however, early trauma exposure may involve overactive and possibly an enlarged amygdala, as well as decreased connectivity of salience hubs such as the dACC. Underlying mechanisms may include interaction with several endocrine systems and result in differential neural response to naturally occurring and added endocrine ligands, as well as sex-specific genetic and epigenetic risk and resilience factors. This complex interaction between multiple biological systems may be associated with sex-specific behavioral patterns, in turn associated with trauma-related psychopathology. While substantial number of published studies present preliminary evidence for neural mechanisms of sex-specific posttraumatic responses, there is a paucity of research directly designed to examine sex as a biological factor in trauma-related psychopathology. Specific foci for future studies aiming to bridge current gaps in the literature are discussed.

A Network-Based Neurobiological Model of PTSD: Evidence From Structural and Functional Neuroimaging Studies

PURPOSE OF REVIEW

Although a fine-grained understanding of the neurobiology of posttraumatic stress disorder (PTSD) is yet to be elucidated, the last two decades have seen a rapid growth in the study of PTSD using neuroimaging techniques. The current review summarizes important findings from functional and structural neuroimaging studies of PTSD, by primarily focusing on their relevance towards an emerging network-based neurobiological model of the disorder.

RECENT FINDINGS

PTSD may be characterized by a weakly connected and hypoactive default mode network (DMN) and central executive network (CEN) that are putatively destabilized by an overactive and hyperconnected salience network (SN), which appears to have a low threshold for perceived saliency, and inefficient DMN-CEN modulation. There is considerable evidence for large-scale functional and structural network dysfunction in PTSD. Nevertheless, several limitations and gaps in the literature need to be addressed in future research.

The Association of PTSD Symptom Severity with Localized Hippocampus and Amygdala Abnormalities

Background

The hippocampus and amygdala have been repeatedly implicated in the psychopathology of posttraumatic stress disorder (PTSD). While numerous structural neuroimaging studies examined these two structures in PTSD, these analyses have largely been limited to volumetric measures. Recent advances in vertex-based neuroimaging methods have made it possible to identify specific locations of subtle morphometric changes within a structure of interest.

Methods

In this cross-sectional study, we used high-resolution magnetic resonance imaging to examine the relationship between PTSD symptomatology, as measured using the Clinician Administered PTSD Scale for the DSM-IV, and structural shape of the hippocampus and amygdala using vertex-wise shape analyses in a group of combat-exposed U.S. Veterans (N = 69).

Results

Following correction for multiple comparisons and controlling for age and cranial volume, we found that participants with more severe PTSD symptoms showed an indentation in the anterior half of the right hippocampus and an indentation in the dorsal region of the right amygdala (corresponding to the centromedial amygdala). Post hoc analysis using stepwise regression suggest that among PTSD symptom clusters, arousal symptoms explain most of the variance in the hippocampal abnormality, whereas reexperiencing symptoms explain most of the variance in the amygdala abnormality.

Conclusion

The results provide evidence of localized abnormalities in the anterior hippocampus and centromedial amygdala in combat-exposed U.S. Veterans suffering from PTSD symptoms. This novel finding provides a more fine-grained analysis of structural abnormalities in PTSD and may be informative for understanding the neurobiology of the disorder.

Altered resting state functional connectivity of fear and reward circuitry in comorbid PTSD and major depression

BACKGROUND

Individuals with comorbid posttraumatic stress disorder and major depressive disorder (PTSD-MDD) often exhibit greater functional impairment and poorer treatment response than individuals with PTSD alone. Research has not determined whether PTSD-MDD is associated with different network connectivity abnormalities than PTSD alone.

METHODS

We used functional magnetic resonance imaging (fMRI) to measure resting state functional connectivity (rs-FC) patterns of brain regions involved in fear and reward processing in three groups: patients with PTSD-alone (n = 27), PTSD-MDD (n = 21), and trauma-exposed healthy controls (TEHCs, n = 34). Based on previous research, seeds included basolateral amygdala (BLA), centromedial amygdala (CMA), and nucleus accumbens (NAcc).

RESULTS

Regardless of MDD comorbidity, PTSD was associated with decreased connectivity of BLA-orbitalfrontal cortex (OFC) and CMA-thalamus pathways, key to fear processing, and fear expression, respectively. PTSD-MDD, compared to PTSD-alone and TEHC, was associated with decreased connectivity across multiple amygdala and striatal-subcortical pathways: BLA-OFC, NAcc-thalamus, and NAcc-hippocampus. Further, while both the BLA-OFC and the NAcc-thalamus pathways were correlated with MDD symptoms, PTSD symptoms correlated with the amygdala pathways (BLA-OFC; CMA-thalamus) only.

CONCLUSIONS

Comorbid PTSD-MDD may be associated with multifaceted functional connectivity alterations in both fear and reward systems. Clinical implications are discussed.

Cortical thickness reduction in combat exposed U.S. veterans with and without PTSD

We investigated the extent of cortical thinning in U.S. Veterans exposed to combat who varied in the severity of their posttraumatic stress disorder (PTSD) symptoms. In addition, we explored the neural correlates of PTSD symptom dimensions and the interactive effects of combat exposure and PTSD upon cortical thickness. Sixty-nine combat exposed Veterans completed high-resolution magnetic resonance imaging (MRI) scans to estimate cortical thickness. The Clinician Administered PTSD Scale (CAPS) and Combat Exposure Scale (CES) assessments were completed to measure current PTSD and historical combat severity, respectively. PTSD symptom dimensions (numbing, avoidance, reexperiencing, anxious arousal, and dysphoric arousal) were studied. Vertex-wise whole cerebrum analyses were conducted. We found widespread negative correlations between CAPS severity and cortical thickness, particularly within the prefrontal cortex. This prefrontal correlation remained significant after controlling for depression severity, medication status, and other potential confounds. PTSD dimensions, except anxious arousal, negatively correlated with cortical thickness in various unique brain regions. CES negatively correlated with cortical thickness in the left lateral prefrontal, regardless of PTSD diagnosis. A significant interaction between CES and PTSD diagnosis was found, such that CES negatively correlated with cortical thickness in the non-PTSD, but not in the PTSD, participants. The results underscore the severity of cortical thinning in U.S. Veterans suffering from high level of PTSD symptoms, as well as in Veterans with no PTSD diagnosis but severe combat exposure. The latter finding raises considerable concerns about a concealed injury potentially related to combat exposure in the post-9/11 era.

Fear extinction and memory reconsolidation as critical components in behavioral treatment for posttraumatic stress disorder and potential augmentation of these processes

Posttraumatic stress disorder (PTSD) is associated with alterations in critical brain regions such as the amygdala, hippocampus, and prefrontal cortex. This brief review has two objectives: (1) to discuss research examining extinction and reconsolidation processes as mechanisms in PTSD psychotherapy, and (2) present possibilities for augmenting extinction and reconsolidation within treatment through alterations to therapeutic interventions and novel approaches. A key component of many effective PTSD therapies is exposure, which involves intentional confrontation and processing of the traumatic memory. Our review suggests that extinction and reconsolidation processes underlie effective exposure-based treatment, but the neurobiological mechanisms of these processes in behavioral treatments for PTSD remains unclear. We argue that enhancing extinction and/or disrupting reconsolidation of a feared memory may improve the efficacy of existing treatments (e.g., increased change for limited/non-responders, faster/greater changes for responders), which can be done through multiple channels. Potential avenues for augmentation of the processes of extinction and reconsolidation in PTSD psychotherapies are reviewed, including behavioral modifications, pharmacotherapy agents, and the use of devices during therapy. We further suggest that investigations towards understanding the extent to which extinction and reconsolidation processes are necessary in effective PTSD psychotherapy is an important future direction for enhancing clinical care among PTSD populations.

Neural changes in extinction recall following prolonged exposure treatment for PTSD: A longitudinal fMRI study

Background

Neurobiological models of posttraumatic stress disorder (PTSD) implicate fear processing impairments in the maintenance of the disorder. Specific deficits in extinction recall, the retention of learned extinction, have been demonstrated. While deficient extinction recall, and the associated activation pattern of prefrontal and hippocampal regions, distinguishes individuals with PTSD from controls, research has not yet examined changes following treatment. We examined the behavioral and neural correlates of extinction recall before and after cognitive behavioral treatment of PTSD.

Methods

Fifty-eight participants (30 with PTSD, 28 trauma-exposed matched controls) underwent a 2-day behavioral fear conditioning, extinction, and recall paradigm during functional magnetic resonance imaging (fMRI). The same procedures were repeated 10 weeks later, after PTSD patients had completed prolonged exposure treatment. We analyzed fMRI data from 32 subjects (16 PTSD; 16 controls) and skin conductance response (SCR) data from 33 subjects (16 PTSD; 17 controls). Neural activity during extinction recall, SCR, and PTSD symptoms were compared across groups and over time.

Results

PTSD patients exhibited pre- to post-treatment reduction in rostral anterior cingulate cortex (rACC) activation during extinction recall, and increase in functional coherence between the rACC and the ventromedial prefrontal cortex (vmPFC) and subgenual anterior cingulate cortex (sgACC). Reduced PTSD symptom severity from pre- to post-treatment was significantly associated with reduced subgenual ACC and parahippocampal activation during this task. SCR during the extinction recall phase did not significantly change with treatment in the PTSD group, but change in SCR was associated with reduction in PTSD symptom severity.

Conclusions

Prolonged exposure treatment appears to alter neural activation in PTSD patients during recall of fear extinction, and change in extinction recall (measured by SCR) is associated with symptom reduction. We discuss results in the context of neural systems involved in response to affective stimuli.

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Deficient recall of extinguished fear (extinction recall; ER) has been associated with PTSD.

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Prolonged exposure (PE) is a first line treatment for PTSD which relies on extinction.

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Changes in prefrontal activation and functional connectivity during ER appeared following PE.

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Changes in ER following PE corresponded to changes in PTSD severity.

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Taken together, these findings suggest normalization of ER deficits in PTSD following PE.