Neural, psychophysiological, and behavioral markers of fear processing in PTSD: a review of the literature

Quantifying Posttraumatic Stress Disorder Symptoms During Traumatic Memories Using Interpretable Markers of Respiratory Variability

BACKGROUND

Posttraumatic stress disorder (PTSD) causes heightened fight-or-flight responses to traumatic memories (i.e., hyperarousal). Although hyperarousal is hypothesized to cause irregular breathing (i.e., respiratory variability), no quantitative markers of respiratory variability have been shown to correspond with PTSD symptoms in humans.

OBJECTIVE

In this study, we define interpretable markers of respiration pattern variability (RPV) and investigate whether these markers respond during traumatic memories, correlate with PTSD symptoms, and differ in patients with PTSD.

METHODS

We recruited 156 veterans from the Vietnam-Era Twin Registry to participate in a trauma recall protocol. From respiratory effort and electrocardiogram measurements, we extracted respiratory timings and rate using a robust quality assessment and fusion approach. We then quantified RPV using the interquartile range and compared RPV between baseline and trauma recall conditions, correlated PTSD symptoms to the difference between trauma recall and baseline RPV (i.e., ∆RPV), and compared ∆RPV between patients with PTSD and trauma-exposed controls. Leveraging a subset of 116 paired twins, we then uniquely controlled for factors shared by co-twins via within-pair analysis for further validation.

RESULTS

We found RPV was increased during traumatic memories (p .001), ∆ RPV was positively correlated with PTSD symptoms (p .05), and patients with PTSD exhibited higher ∆ RPV than trauma-exposed controls (p . 05).

CONCLUSIONS

This paper is the first to elucidate RPV markers that respond during traumatic memories, especially in patients with PTSD, and correlate with PTSD symptoms.

SIGNIFICANCE

These findings encourage future studies outside the clinic, where interpretable markers of respiratory variability are used to track hyperarousal.

Early traumatic experiences are linked to hypersexual behavior and erectile dysfunction in men through the mediation of body uneasiness and general psychopathology

BACKGROUND

Childhood traumatic experiences have been associated with hypersexuality and sexual dysfunctions. However, the mediators of the interactions between these variables should be clarified in men.

AIM

This study aimed to investigate the interaction of early traumatic experiences, psychopathology, and sexuality with respect to erectile dysfunction (ED) and hypersexual behavior. The hypothesized model expected that traumatic experiences would be associated with hypersexual behavior and reduced sexual functioning through the mediation of body uneasiness and psychological distress.

METHODS

The study was cross-sectional and observational. A total of 317 men were enrolled. Male patients with a primary complaint of ED and an indication for psychiatry referral represented the clinical sample (n = 116; mean ± SD age, 42.82 ± 16.89 years). Clinical classification was assessed with the Structured Interview on Erectile Dysfunction. The second sample (n = 201, 30.82 ± 11.94 years) was recruited from the general population. All participants were administered the following questionnaires: Brief Symptom Inventory, Childhood Trauma Questionnaire-Short Form, Hypersexual Behavior Inventory, Body Uneasiness Test-A, and 5-item International Index of Erectile Function.

OUTCOMES

Psychopathology and sexual functioning were assessed by a dimensional approach, and a multivariate model was computed by structural equation model analysis.

RESULTS

When compared with the sample from the general population, the clinical sample exhibited a higher prevalence of early traumatic experiences, as measured by scores on the Childhood Trauma Questionnaire-Short Form (45.08 ± 14.25 vs 39.03 ± 10.22, F = 17.63, P < .001), and a higher tendency to engage in hypersexual behaviors (34.63 ± 13.55 vs 30.79 ± 12.44, F = 6.97, P < .01). Structural equation model analysis showed excellent fit indices indicating that early traumatic experiences predicted hypersexual behaviors and ED through the exacerbating mediating effect of body uneasiness and psychopathology.

CLINICAL IMPLICATIONS

Clinicians should not limit their attention to the behavioral level when assessing sexual dysfunction in men; rather, they should also consider the complex psychopathologic consequences of childhood trauma. Integrated treatments that address the potential presence of childhood trauma with its wider psychological correlates (eg, emotion dysregulation, body uneasiness) might improve treatment response.

STRENGTHS AND LIMITATIONS

The study reports novel data on the relationship among childhood maltreatment, male sexuality, and psychopathologic mediators with a dimensional assessment. However, the assessment was cross-sectional, and causality was mainly derived from previous studies.

CONCLUSION

The present study enriches the current literature, strengthening the hypothesis that childhood traumatic experiences significantly shape development and sexuality. Body uneasiness and psychopathology can both tax sexual functioning, as assessed by erectile functioning or hypersexuality.

Neural correlates of context-dependent extinction recall in social anxiety disorder: relevance of intrusions in response to aversive social experiences

BACKGROUND

There are phenomenological similarities between social anxiety disorder (SAD) and posttraumatic stress disorder, such as a provoking aversive event, posttraumatic stress symptoms (e.g. intrusions) in response to these events and deficient (context-dependent) fear conditioning processes. This study investigated the neural correlates of context-dependent extinction recall and fear renewal in SAD, specifically in patients with intrusions in response to an etiologically relevant aversive social event.

METHODS

During functional magnetic resonance imaging a two-day context-dependent fear conditioning paradigm was conducted in 54 patients with SAD and 54 healthy controls (HC). This included fear acquisition (context A) and extinction learning (context B) on one day, and extinction recall (context B) as well as fear renewal (contexts C and A) one day later. The main outcome measures were blood oxygen level-dependent responses in regions of interest and skin conductance responses.

RESULTS

Patients with SAD showed reduced differential conditioned amygdala activation during extinction recall in the safe extinction context and during fear renewal in the acquisition context compared to HC. Patients with clinically relevant intrusions moreover exhibited hypoactivation of the ventromedial prefrontal cortex (vmPFC) during extinction learning, extinction recall, and fear renewal in a novel context, while amygdala activation more strongly decreased during extinction learning and increased during fear renewal in the acquisition context compared with patients without intrusions.

CONCLUSIONS

Our study provides first evidence that intrusions in SAD are associated with similar deficits in context-dependent regulation of conditioned fear via the vmPFC as previously demonstrated in posttraumatic stress disorder.

Predicting Fear Extinction in Posttraumatic Stress Disorder

Fear extinction is the basis of exposure therapies for posttraumatic stress disorder (PTSD), but half of patients do not improve. Predicting fear extinction in individuals with PTSD may inform personalized exposure therapy development. The participants were 125 trauma-exposed adults (96 female) with a range of PTSD symptoms. Electromyography, electrocardiogram, and skin conductance were recorded at baseline, during dark-enhanced startle, and during fear conditioning and extinction. Using a cross-validated, hold-out sample prediction approach, three penalized regressions and conventional ordinary least squares were trained to predict fear-potentiated startle during extinction using 50 predictor variables (5 clinical, 24 self-reported, and 21 physiological). The predictors, selected by penalized regression algorithms, were included in multivariable regression analyses, while univariate regressions assessed individual predictors. All the penalized regressions outperformed OLS in prediction accuracy and generalizability, as indexed by the lower mean squared error in the training and holdout subsamples. During early extinction, the consistent predictors across all the modeling approaches included dark-enhanced startle, the depersonalization and derealization subscale of the dissociative experiences scale, and the PTSD hyperarousal symptom score. These findings offer novel insights into the modeling approaches and patient characteristics that may reliably predict fear extinction in PTSD. Penalized regression shows promise for identifying symptom-related variables to enhance the predictive modeling accuracy in clinical research.

Modeling integrated stress, sleep, fear and neuroimmune responses: Relevance for understanding trauma and stress-related disorders

Sleep and stress have complex interactions that are implicated in both physical diseases and psychiatric disorders. These interactions can be modulated by learning and memory, and involve additional interactions with the neuroimmune system. In this paper, we propose that stressful challenges induce integrated responses across multiple systems that can vary depending on situational variables in which the initial stress was experienced, and with the ability of the individual to cope with stress- and fear-inducing challenges. Differences in coping may involve differences in resilience and vulnerability and/or whether the stressful context allows adaptive learning and responses. We provide data demonstrating both common (corticosterone, SIH and fear behaviors) and distinguishing (sleep and neuroimmune) responses that are associated with an individual's ability to respond and relative resilience and vulnerability. We discuss neurocircuitry regulating integrated stress, sleep, neuroimmune and fear responses, and show that responses can be modulated at the neural level. Finally, we discuss factors that need to be considered in models of integrated stress responses and their relevance for understanding stress-related disorders in humans.

Sex differences in contextual pattern separation, neurogenesis, and functional connectivity within the limbic system

Background

Females are more likely to present with anxiety disorders such as post-traumatic stress disorder (PTSD) compared to males, which are associated with disrupted hippocampal integrity. Sex differences in the structure and function of hippocampus exist. Here, we examined sex differences in contextual pattern separation, functional connectivity, and activation of new neurons during fear memory.

Methods

Two-month-old male and female Sprague-Dawley rats were injected with the DNA synthesis markers, iododeoxyuridine (IdU) and chlorodeoxyuridine (CldU) 3 weeks and 4 weeks before perfusion, respectively. One week after CldU injection, the rats underwent a context discrimination task in which rats were placed in context A (shock) and context A’ (no shock) every day for 12 days. On the test day, rats were placed in the shock context (context A) to measure fear memory and expression of zif268, an immediate early gene across 16 different limbic and reward regions. Repeated-measures or factorial analysis of variance was conducted on our variables of interest. Pearson product-moment calculations and principal component analyses on zif268 expression across regions were also performed.

Results

We found that females, but not males, showed contextual discrimination during the last days of training. On the test day, both sexes displayed similar levels of freezing, indicating equivalent fear memory for context A. Despite similar fear memory, males showed more positive correlations of zif268 activation between the limbic regions and the striatum, whereas females showed more negative correlations among these regions. Females showed greater activation of the frontal cortex, dorsal CA1, and 3-week-old adult-born dentate granular cells compared to males.

Conclusions

These results highlight the importance of studying sex differences in fear memory and the contribution of adult neurogenesis to the neuronal network and may contribute to differences in susceptibility to fear-related disorders such as post-traumatic stress disorder.

Highlights

Female rats, but not male rats, show faster discrimination during a contextual pattern separation task.

Three-week-old adult-born neurons are more active in response to fear memory in females compared to males.

Females had greater neural activation compared to males in the frontal cortex and dorsal CA1 region of the hippocampus in response to fear memory.

Males and females show distinct patterns in functional connectivity for fear memory across limbic regions.

Males have many positive correlations between activated new neurons of different ages between the dorsal and ventral hippocampus, while females show more correlations between activated new neurons and other limbic regions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13293-022-00450-2.

Resting-state EEG functional connectivity predicts post-traumatic stress disorder subtypes in veterans

Objective. Post-traumatic stress disorder (PTSD) is highly heterogeneous, and identification of quantifiable biomarkers that could pave the way for targeted treatment remains a challenge. Most previous electroencephalography (EEG) studies on PTSD have been limited to specific handpicked features, and their findings have been highly variable and inconsistent. Therefore, to disentangle the role of promising EEG biomarkers, we developed a machine learning framework to investigate a wide range of commonly used EEG biomarkers in order to identify which features or combinations of features are capable of characterizing PTSD and potential subtypes.Approach. We recorded 5 min of eyes-closed and 5 min of eyes-open resting-state EEG from 202 combat-exposed veterans (53% with probable PTSD and 47% combat-exposed controls). Multiple spectral, temporal, and connectivity features were computed and logistic regression, random forest, and support vector machines with feature selection methods were employed to classify PTSD. To obtain robust results, we performed repeated two-layer cross-validation to test on an entirely unseen test set.Main results. Our classifiers obtained a balanced test accuracy of up to 62.9% for predicting PTSD patients. In addition, we identified two subtypes within PTSD: one where EEG patterns were similar to those of the combat-exposed controls, and another that were characterized by increased global functional connectivity. Our classifier obtained a balanced test accuracy of 79.4% when classifying this PTSD subtype from controls, a clear improvement compared to predicting the whole PTSD group. Interestingly, alpha connectivity in the dorsal and ventral attention network was particularly important for the prediction, and these connections were positively correlated with arousal symptom scores, a central symptom cluster of PTSD.Significance. Taken together, the novel framework presented here demonstrates how unsupervised subtyping can delineate heterogeneity and improve machine learning prediction of PTSD, and may pave the way for better identification of quantifiable biomarkers.

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

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

Trauma exposure among cannabis use disorder individuals was associated with a craving-correlated non-habituating amygdala response to aversive cues

The relationship of cannabis-use disorder and trauma exposure at the level of the brain is not well-understood. Cue-reactivity paradigms have largely focused on characterizing aberrant subcortical function by averaging across the entire task. However, changes across the task, including a non-habituating amygdala response (NHAR), may be a useful biomarker for relapse vulnerability and other pathology. This secondary analysis utilized existing fMRI data from a CUD population with (TR-Y, n = 18) or without trauma (TR-N, n = 15). Amygdala reactivity to novel and repeated aversive cues was examined between TR-Y vs. TR-N groups, using a repeated measures ANOVA. Analysis revealed a significant interaction between TR-Y vs. TR-N and amygdala response to novel vs. repeated cues in the amygdala (right: F (1,31) = 5.31, p = 0.028; left: F (1,31) = 7.42, p = 0.011). In the TR-Y group, a NHAR was evident, while the TR-N group exhibited amygdala habituation, resulting in a significant difference between groups of amygdala reactivity to repeated cues (right: p = 0.002; left: p < 0.001). The NHAR in the TR-Y (but not TR-N) group was significantly correlated with higher cannabis craving scores, yielding a significant group difference (z = 2.1, p = 0.018). Results suggest trauma interacts with the brain's sensitivity to aversive cues, offering a neural explanation for the relationship between trauma and CUD vulnerability. These findings suggest the importance of considering the temporal dynamics of cue reactivity and trauma history in future studies and treatment planning, as this distinction may help decrease relapse vulnerability.

Life threat during assaultive trauma: Critical posttraumatic stress disorder risk factors for injured patients

BACKGROUND

Rates of posttraumatic stress disorder (PTSD) among injury survivors are higher relative to the general population, supporting the need to identify those most at risk for PTSD following injury given negative impact of PTSD on recovery. Perceived life threat and assaultive trauma are consistent risk factors for subsequent PTSD development, although less work has explored them in combination. The current study evaluated whether trauma type (assaultive vs. nonassaultive) and perceived life threat, together, led to greater PTSD symptoms 1 month and 6 months postinjury.

METHODS

Participants included adult injured trauma survivors admitted to a level 1 trauma center. While hospitalized, perceived life threat during trauma was assessed and mechanism of injury was collected via record review and was collapsed into two categories: assaultive and nonassaultive. The Clinician-Administered PTSD Scale (Diagnostic and Statistical Manual of Mental Disorders [Fifth Edition]) was administered at 1 month (N = 137) and 6 months (N = 220) after injury.

RESULTS

The four symptoms clusters of PTSD (intrusions, avoidance, hyperarousal, and negative mood/cognitions) were examined using four 2 (time) × 2 (life threat) × 2 (trauma type) mixed methods analyses of variance to assess differences based on risk factors and time. Results showed significant interaction effects of life threat, trauma type, and time for intrusive symptoms and avoidance symptoms. Individuals with life threat during assaultive traumas maintained heightened intrusive symptoms across time and increased avoidance at 6 months. On the other hand, participants with either life threat or assaultive traumas had decreased symptoms at 6 months.

CONCLUSION

Experiencing assaultive trauma and life threat led to greater symptoms of PTSD. Individuals with assaultive traumas who experienced life threat may represent a specific at-risk group following injury. Avoidance can protract functional impairment and impede access to care, negatively impacting recovery. This study highlights a need to assess for these peritrauma factors during hospitalization and supports early intervention targeting avoidance and intrusive symptoms in this group.

LEVEL OF EVIDENCE

Prognostic/Epidemiologic, Level IV.

Relationship of parent-rated and objectively evaluated executive function to symptoms of posttraumatic stress and attention-deficit/hyperactivity disorder in homeless youth

Compared to their stably housed peers, homeless, and highly mobile (HHM) youth experience disproportionately greater adversity and risk leading to a wide variety of poor developmental outcomes, and targeted interventions have the potential to mitigate such outcomes. A growing literature highlights the need for accurate diagnosis in high-risk populations given the considerable overlap between posttraumatic symptomology and behaviorally based disorders such as ADHD. Objective testing inferring neurobiological and circuit-based abnormalities in posttraumatic stress disorder (PTSD) and ADHD may provide a useful clinical tool to aid accurate diagnosis and treatment recommendations. This novel, exploratory study examined the relation between executive function (EF) as measured by objective testing and parent ratings with symptoms of posttraumatic stress and ADHD in 86 children (age 9 to 11) living in emergency homeless shelters. Parent-rated EF problems suggested broad impairment associated with ADHD symptoms but specific impairment in emotional/behavioral function associated with posttraumatic stress symptoms. While measures of inhibition and shifting EF were strongly associated with symptomology in bivariate correlations, they explained minimal variance in regression models. Internalizing behavior problems were associated with posttraumatic stress symptoms, while externalizing behavior problems were associated with ADHD symptoms. Implications for clinical practice and future research are discussed.

EEG Neurofeedback for Anxiety Disorders and Post-Traumatic Stress Disorders: A Blueprint for a Promising Brain-Based Therapy

PURPOSE OF REVIEW

This review provides an overview of current knowledge and understanding of EEG neurofeedback for anxiety disorders and post-traumatic stress disorders.

RECENT FINDINGS

The manifestations of anxiety disorders and post-traumatic stress disorders (PTSD) are associated with dysfunctions of neurophysiological stress axes and brain arousal circuits, which are important dimensions of the research domain criteria (RDoC). Even if the pathophysiology of these disorders is complex, one of its defining signatures is behavioral and physiological over-arousal. Interestingly, arousal-related brain activity can be modulated by electroencephalogram-based neurofeedback (EEG NF), a non-pharmacological and non-invasive method that involves neurocognitive training through a brain-computer interface (BCI). EEG NF is characterized by a simultaneous learning process where both patient and computer are involved in modifying neuronal activity or connectivity, thereby improving associated symptoms of anxiety and/or over-arousal. Positive effects of EEG NF have been described for both anxiety disorders and PTSD, yet due to a number of methodological issues, it remains unclear whether symptom improvement is the direct result of neurophysiological changes targeted by EEG NF. Thus, in this work we sought to bridge current knowledge on brain mechanisms of arousal with past and present EEG NF therapies for anxiety and PTSD. In a nutshell, we discuss the neurophysiological mechanisms underlying the effects of EEG NF in anxiety disorder and PTSD, the methodological strengths/weaknesses of existing EEG NF randomized controlled trials for these disorders, and the neuropsychological factors that may impact NF training success.

Efficacy of exposure in group settings for youth with posttraumatic stress symptoms

BACKGROUND

Exposure to traumatic experiences is a fundamental part of evidence-based trauma-focused cognitive behavioral treatment (CBT) but in group settings it is discussed controversially among researchers and practitioners. This study aims to examine the individual participants' stress level during group sessions with exposure and disclosure of traumatic events.

METHOD

N = 47 traumatized youth (M_age = 17.00, 94% male) participated in a group intervention comprising six 90-min group sessions (exposure in sessions 2-5). It is based on trauma-focused CBT principles. The individual stress level was assessed by the participants and group facilitators at the beginning, during, and at the end of every session.

RESULTS

During the sessions including exposure, the stress level of the participants was higher than during sessions without exposure (Z = - 3.79; p ≤ .001). During the exposure sessions, the participants showed significant changes in stress level (d = 0.34-0.87) following an inverse U-shaped trend.

CONCLUSION

The results show that exposure is feasible within the scope of a trauma-focused group intervention for youth. The further dissemination of trauma-focused group treatments is an important component in the mental health care of children and youth who are traumatized.

Altered resting-state functional connectivity of the default mode and central executive networks following cognitive processing therapy for PTSD

Psychotherapy research is increasingly targeting both psychological and neurobiological mechanisms of therapeutic change. This trend is evident in and applicable to post-traumatic stress disorder (PTSD) treatment research given the high nonresponse rate of individuals with PTSD who undergo cognitive-behavioral therapy (CBT). Functional connectivity analyses investigating disrupted brain networks across mental disorders have been employed to understand both mental disorder symptoms and therapeutic mechanisms. However, few studies have examined pre-post CBT brain changes in PTSD using functional connectivity analyses. The current study investigated a) whether brain networks commonly implicated in psychopathology (e.g., default mode network [DMN], central executive network [CEN], and salience network [SN]) changed following Cognitive Processing Therapy (CPT) for PTSD and b) whether change in these networks was associated with PTSD and/or transdiagnostic symptom change. Independent components analysis was implemented to investigate resting-state functional connectivity in DMN, CEN, and SN in 42 women with PTSD and 18 trauma-exposed controls (TEC). Results indicated decreased CEN-cerebellum connectivity in PTSD participants versus TEC prior to CPT and decreased DMN connectivity in PTSD participants after CPT. Additionally, DMN and SN connectivity was related to change in positive and negative affectivity, while exploratory analyses at a cluster threshold of pFDR < .10 indicated DMN and SN connectivity was also related to change in PTSD symptoms and rumination. These findings provide evidence for normalization of CEN connectivity with treatment and implicate the DMN and SN in clinical symptom change following CPT.

Impulsivity as a multifactorial construct and its relationship to PTSD severity and threat sensitivity

Changes to the DSM-5's conceptualization of posttraumatic stress disorder (PTSD) highlight the importance of impulsivity within the context of PTSD-related arousal dysregulation. While the relationship between PTSD and threat sensitivity is well defined, how they relate to impulsivity remains understudied. We examined the relationship between PTSD symptom severity, threat sensitivity, and impulsivity. 124 participants completed the PTSD Checklist (PCL-C) and the Barratt Impulsiveness Scale 11th ed (BIS-11). BIS-11 items were separated to define cognitive and behavioral impulsivity subdomains. A trauma-exposed subsample of 39 participants were also exposed to no, ambiguous, and high threat conditions in a threat-enhanced acoustic startle paradigm with psychophysiological response as the outcome variable. PTSD severity was significantly associated with greater overall impulsivity and behavioral impulsivity. Greater overall impulsivity and both cognitive and behavioral impulsivity subdomains were significantly associated with psychophysiological magnitudes across threat conditions in the traumatized subsample. Our results suggest PTSD severity may linked to behavioral impulsivity and both cognitive and behavioral impulsivity are associated with threat sensitivity and hyperarousal. Assessing impulsivity within the context of PTSD, particularly in terms of its cognitive and behavioral subdomains, may provide important, clinically relevant information.

Adverse caregiving in early life: The trauma and deprivation distinction in young children

Knowledge and understanding about the impact of cumulative adverse experiences on the health and wellbeing of children, adolescents, and adults has rapidly expanded over the past 30 years. Despite the invaluable attention and support this proliferation has drawn to the importance of early childhood experiences, we believe that it is time to move beyond broad indices of risk and toward more specific and individualized understanding of how risk exposures are linked to clinical outcomes in young children. Within infant and early childhood mental health, there is a need for greater specificity in linking adverse caregiving experiences in early life to psychopathology in children. We highlight a framework distinguishing experiences of trauma from experiences of deprivation and use the examples of posttraumatic stress disorder and reactive attachment disorder to demonstrate how greater specificity in our understanding of early adverse caregiving can lead to more accurate and targeted diagnosis and treatment for young children. Both researchers and clinicians benefit from an approach to gain a greater appreciation of the links between specific types of experiences and outcomes in the children that we serve.

Neural signatures of conditioning, extinction learning, and extinction recall in posttraumatic stress disorder: a meta-analysis of functional magnetic resonance imaging studies

BACKGROUND

Establishing neurobiological markers of posttraumatic stress disorder (PTSD) is essential to aid in diagnosis and treatment development. Fear processing deficits are central to PTSD, and their neural signatures may be used as such markers.

METHODS

Here, we conducted a meta-analysis of seven Pavlovian fear conditioning fMRI studies comparing 156 patients with PTSD and 148 trauma-exposed healthy controls (TEHC) using seed-based d-mapping, to contrast neural correlates of experimental phases, namely conditioning, extinction learning, and extinction recall.

RESULTS

Patients with PTSD, as compared to TEHCs, exhibited increased activation in the anterior hippocampus (extending to the amygdala) and medial prefrontal cortex during conditioning; in the anterior hippocampus-amygdala regions during extinction learning; and in the anterior hippocampus-amygdala and medial prefrontal areas during extinction recall. Yet, patients with PTSD have shown an overall decreased activation in the thalamus during all phases in this meta-analysis.

CONCLUSION

Findings from this metanalysis suggest that PTSD is characterized by increased activation in areas related to salience and threat, and lower activation in the thalamus, a key relay hub between subcortical areas. If replicated, these fear network alterations may serve as objective diagnostic markers for PTSD, and potential targets for novel treatment development, including pharmacological and brain stimulation interventions. Future longitudinal studies are needed to examine whether these observed network alteration in PTSD are the cause or the consequence of PTSD.

Neural function during emotion processing and modulation associated with treatment response in a randomized clinical trial for posttraumatic stress disorder

BACKGROUND

Posttraumatic stress disorder (PTSD) has been associated with exaggerated threat processing and deficits in emotion modulation circuitry. It remains unknown how neural circuits are associated with response to evidence-based treatments for PTSD.

METHOD

We examined associations between PTSD symptoms and indicators of neural response in key emotion processing and modulation regions. Fifty-six military Veterans with PTSD were randomly assigned to one of three evidence-based treatments (prolonged exposure, sertraline, and PE plus sertraline) in a randomized clinical trial ("PROGrESS"; 2018, Contemp Clin Trials, 64, 128-138). Twenty-seven combat-exposed controls (CCs) served as a comparison group at pretreatment. Before and after PTSD treatment, functional magnetic resonance imaging was used to assess brain activation and connectivity during the validated Shifted Attention Emotion Appraisal Task (2003, J Neurosci, 23, 5627-5633; 2013, Biol Psychiatry, 73, 1045-1053).

RESULTS

Greater activation in emotion processing (anterior insula) and modulation (prefrontal cortex) regions and increased connectivity between attentional control (dorsolateral prefrontal cortex and superior parietal cortex) and emotion processing (amygdala) regions, at pretreatment, were associated with subsequent PTSD symptom improvement.

CONCLUSIONS

This study is one of the first to examine task-based activation and functional connectivity in a PTSD treatment trial, and provides evidence to suggest that activation in and connectivity between emotion processing and modulation regions are important predictors of treatment response.

Shame Proneness, Negative Cognitions, and Posttraumatic Stress Among Women with a History Sexual Trauma

While fear and anger have been extensively studied as emotions involved in posttraumatic stress disorder, shame is an important emotion to examine in those who have experienced a traumatic event, as it is often associated with treatment avoidance and treatment resistance. Compared to guilt, which is associated with having participated in something that violates social/cultural norms or expectations, shame is associated with a negative perception of the self. The current paper sought to examine the role of shame proneness and guilt proneness, as it relates to posttraumatic cognitions and posttraumatic stress symptoms (PTSS) among women reporting a history of sexual trauma. Seventy-two community-recruited women with a history of sexual trauma completed self-report measures of shame and guilt proneness and negative posttraumatic cognitions as well as a semi-structured interview assessing PTSS. There was an indirect effect of shame proneness on PTSS, through its positive association with negative cognitions about the self but not others or the world. Guilt proneness was not significantly related to PTSS or negative posttraumatic cognitions. The current paper outlines the importance of these findings and future directions for continuing to better understand the relations between shame and posttraumatic stress disorder symptoms and treatment.

Stathmin Regulates Spatiotemporal Variation in the Memory Loop in Single-Prolonged Stress Rats

Posttraumatic stress disorder (PTSD) is closely related to brain structures of the memory loop such as the hippocampus, amygdala, and medial prefrontal cortex (mPFC). The fear gene stathmin plays an important role in regulating fear memory. However, whether the fear gene stathmin is related to fear memory loop anomalies caused by PTSD is unclear. A single-prolonged stress (SPS) rat model of PTSD was constructed. Wistar rats were randomly divided into 5 groups: the control group, SPS 1-day group, SPS 4-day group, SPS 7-day group, and SPS 14-day group. Then, we measured the protein and mRNA expression of stathmin, p-stathmin (Ser16, Ser25, Ser38, and Ser63), β-tubulin, and MAP-1B in the hippocampus, amygdala, and mPFC in the 5 groups by immunohistochemistry, Western blotting, and qRT-PCR. The expression of the stathmin protein in the hippocampus, mPFC, and amygdala of the rat memory loop decreased gradually in the SPS 1-day group, the SPS 4-day group, and the SPS 7-day group, in which it was the lowest, and then increased. The trend of the expression of stathmin mRNA in the three areas of the memory loop was consistent with the trend of the expression of the stathmin protein. The trend of the protein expression of p-stathmin (Ser25 and Ser38) was opposite of that of stathmin; it reached a peak on the 7th day, and then decreased in the hippocampus. The protein expression of p-stathmin (Ser63) showed the same trend in the mPFC. The protein and mRNA expression of β-tubulin and MAP-1B was consistent with that of p-stathmin; it reached a peak on the 7th day, and then decreased in the rat hippocampus, mPFC, and amygdala. Stathmin in the memory loop, especially in the hippocampus, regulates microtubule structure through its phosphorylation at Ser25 and Ser38 and thereby participates in the mediation of fear memory abnormalities in PTSD.

Animal models of liability to post-traumatic stress disorder: going beyond fear memory

In this review, we advocate a dimensional approach on the basis of candidate endophenotypes to the development of animal models of post-traumatic stress disorder (PTSD) capable of including genetic liability factors, variations in symptoms profile and underlying neurobiological mechanisms, and specific comorbidities. Results from the clinical literature pointed to two candidate endophenotypes of PTSD: low sensory gating and high waiting impulsivity. Findings of comparative studies in mice of two inbred strains characterized by different expressions of the two candidate endophenotypes showed different strain-specific neural and behavioral effects of stress experiences. Thus, mice of the standard C57BL/6J strain show stress-induced helplessness, stress-learned helplessness, and stress-extinction-resistant conditioned freezing. Instead, mice of the genetically unrelated DBA/2J strain, expressing both candidate endophenotypes, show stress-induced extinction-resistant avoidance and neural and behavioral phenotypes promoted by prolonged exposure to addictive drugs. These strain differences are in line with evidence of associations between genetic variants and specific stress-promoted pathological profiles in PTSD, support a role of genotype in determining different PTSD comorbidities, and offer the means to investigate specific pathogenic processes.

Processing of affective words in adolescent PTSD-Attentional bias toward social threat

Post-traumatic stress disorder (PTSD) is associated with a hypersensitivity to potential threat. This hypersensitivity manifests through differential patterns of emotional information processing and has been demonstrated in behavioral and neurophysiological experimental paradigms. However, the majority of research has been focused on adult patients with PTSD. To examine possible differences in underlying neurophysiological patterns for adolescent patients with PTSD after childhood sexual and/or physical abuse (CSA/CPA), ERP correlates of emotional word processing in 38 healthy participants and 40 adolescent participants with PTSD after experiencing CSA/CPA were studied. The experimental paradigm consisted of a passive reading task with neutral, positive (e.g., paradise), physically threatening (e.g., torment), and socially threatening (i.e., swearing, e.g., son of a bitch) words. A modulation of P3 amplitudes by emotional valence was found, with positive words inducing less elevated amplitudes over both groups. Interestingly, in later processing, the PTSD group showed augmented early late positive potential (LPP) amplitudes for socially threatening stimuli, while there were no modulations within the healthy control group. Also, region-specific emotional modulations for anterior and posterior electrode clusters were found. For the anterior LPP, highest activations have been found for positive words, while socially and physically threatening words led to strongest modulations in the posterior LPP cluster. There were no modulations by group or emotional valence at the P1 and EPN stage. The findings suggest an enhanced conscious processing of socially threatening words in adolescent patients with PTSD after CSA/CPA, pointing to the importance of a disjoined examination of threat words in emotional processing research.

In Trauma-Exposed Individuals, Self-reported Hyperarousal and Sleep Architecture Predict Resting-State Functional Connectivity in Frontocortical and Paralimbic Regions

BACKGROUND

Symptoms of posttraumatic stress disorder (PTSD) reflect abnormalities in large-scale brain networks. In individuals with recent trauma exposure, we examined associations of seed-based resting-state functional connectivity (rs-FC) with posttraumatic symptoms and sleep. We hypothesized that more severe PTSD symptoms and poorer sleep quality would predict 1) greater rs-FC between fear-related seeds and other fear-related regions and 2) lesser rs-FC between fear-related seeds and emotion-regulatory regions.

METHODS

Seventy-four participants who had experienced a DSM-5 criterion A stressor within the past 2 years and ranged from asymptomatic to fully meeting criteria for PTSD diagnosis underwent 14 days of actigraphy and sleep diaries, a night of ambulatory polysomnography, and a functional magnetic resonance imaging resting-state scan at 3T. rs-FC measures of 5 fear-related seeds and 1 emotion regulatory seed with regions of the anterior cerebrum were correlated with PTSD symptoms, objective and subjective habitual sleep quality, and sleep architecture.

RESULTS

Longer objective habitual sleep onset latency was associated with greater connectivity between fear-related seeds and other regions of the salience network. Greater PTSD symptoms were associated with less connectivity between fear-related seeds and anterior emotion regulatory regions, whereas greater percent slow wave sleep was associated with more connectivity between these regions. However, other objective and subjective measures reflecting better habitual sleep quality were associated with less rs-FC between these regions.

CONCLUSIONS

Longer sleep onset latency predicted greater rs-FC among fear-related areas. More severe PTSD symptoms predicted less rs-FC between fear and fear regulatory regions reflecting putatively reduced top-down fear regulation. Some (e.g., percent slow wave sleep), but not all sleep indices predicted greater top-down fear regulation.

Attention to threat in posttraumatic stress disorder as indexed by eye-tracking indices: a systematic review

BACKGROUND

Cognitive models of posttraumatic stress disorder (PTSD) implicate threat-related attentional biases in the etiology and phenomenology of the disorder. However, extant attentional research using reaction time (RT)-based paradigms and measures has yielded mixed results. Eye-tracking methodology has emerged in recent years to overcome several inherent drawbacks of RT-based tasks, striving to better delineate attentional processes.

METHODS

A systematic review of experimental studies examining threat-related attention biases in PTSD, using eye-tracking methodology and group-comparison designs, was conducted conforming to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Studies were selected following a systematic search for publications between 1980 and December 2017 in PsycINFO, MEDLINE and the National Center for PTSD Research's Published International Literature on Traumatic Stress (PILOTS) database. Additional records were identified by employing the Similar Articles feature in PubMed, and the Cited Reference Search in ISI Web of Science. Reference sections of review articles, book chapters and studies selected for inclusion were searched for further studies. Ongoing studies were also sought through Clinicaltrials.gov.

RESULTS

A total of 11 studies (n = 456 participants in total) were included in the final review. Results indicated little support for enhanced threat detection, hypervigilance and attentional avoidance. However, consistent evidence emerged for sustained attention on threat (i.e. attention maintenance) in PTSD.

CONCLUSIONS

This review is the first to systematically evaluate extant findings in PTSD emanating from eye-tracking studies employing group-comparison designs. Results suggest that sustained attention on threat might serve as a potential target for therapeutic intervention.

The Sound and Face of Others: Vocal Priming Effects on Facial Emotion Processing in Posttraumatic Stress Disorder

INTRODUCTION

Facial expressions and vocal intonation are key signals in the communication of emotions. Individuals with posttraumatic stress disorder (PTSD) are known to show an impaired perception of facial emotions. So far, research on multimodal emotional stimuli or the priming effects on emotion processing has been absent in PTSD. Therefore, we conducted a study to investigate the influence of vocal priming on facial emotion processing and classification in PTSD using electroencephalography.

METHODS

Twenty-one women with PTSD compared to 28 healthy women were asked to classify emotion-morphed faces with predominantly angry, ambiguous, or predominantly happy expressions primed by either an angry or a happy voice. Responses and reaction times as well as the N170, a component reflecting configural face processing, were analyzed.

RESULTS

Patients with PTSD were slower in classifying emotional faces that were primed by either an angry or happy voice compared to the healthy controls (HCs; η2 = 0.14). Additionally, patients with PTSD were faster in classifying facial expressions after angry compared to happy vocal primes (η2 = 0.14). HCs did not show this effect. Correlation analyses revealed positive associations between emotion (dys-)regulation and reaction times in patients with PTSD but not in HCs (r = 0.64-0.76). Furthermore, patients with PTSD showed greater N170 amplitudes for predominantly angry and ambiguous faces than HCs (η2 = 0.07).

CONCLUSION

Data suggest that patients with PTSD experience more difficulties when processing complex social stimuli than HCs. The altered processing of complex social-emotional signals could amplify PTSD symptoms, thus qualifying as an explicit therapy target.

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.

Acute Stress-Induced Epigenetic Modulations and Their Potential Protective Role Toward Depression

Psychiatric disorders entail maladaptive processes impairing individuals’ ability to appropriately interface with environment. Among them, depression is characterized by diverse debilitating symptoms including hopelessness and anhedonia, dramatically impacting the propensity to live a social and active life and seriously affecting working capability. Relevantly, besides genetic predisposition, foremost risk factors are stress-related, such as experiencing chronic psychosocial stress—including bullying, mobbing and abuse—, and undergoing economic crisis or chronic illnesses. In the last few years the field of epigenetics promised to understand core mechanisms of gene-environment crosstalk, contributing to get into pathogenic processes of many disorders highly influenced by stressful life conditions. However, still very little is known about mechanisms that tune gene expression to adapt to the external milieu. In this Perspective article, we discuss a set of protective, functionally convergent epigenetic processes induced by acute stress in the rodent hippocampus and devoted to the negative modulation of stress-induced immediate early genes (IEGs) transcription, hindering stress-driven morphostructural modifications of corticolimbic circuitry. We also suggest that chronic stress damaging protective epigenetic mechanisms, could bias the functional trajectory of stress-induced neuronal morphostructural modification from adaptive to maladaptive, contributing to the onset of depression in vulnerable individuals. A better understanding of the epigenetic response to stress will be pivotal to new avenues of therapeutic intervention to treat depression, especially in light of limited efficacy of available antidepressant drugs.

Antagonism of corticotropin releasing factor in the basolateral amygdala of resilient and vulnerable rats: Effects on fear-conditioned sleep, temperature and freezing

The basolateral nucleus of the amygdala (BLA) plays a significant role in mediating individual differences in the effects of fear memory on sleep. Here, we assessed the effects of antagonizing corticotropin releasing factor receptor 1 (CRFR1) after shock training (ST) on fear-conditioned behaviors and sleep. Outbred Wistar rats were surgically implanted with electrodes for recording EEG and EMG and with bilateral guide cannulae directed at BLA. Data loggers were placed intraperitoneally to record core body temperature. The CRFR1 antagonist, antalarmin (ANT; 4.82 mM) was microinjected into BLA after shock training (ST: 20 footshocks, 0.8 mA, 0.5 s duration, 60 s interstimulus interval), and the effects on sleep, freezing and the stress response (stress-induced hyperthermia, SIH) were examined after ST and fearful context re-exposure alone at 7 days (CTX1) and 21 days (CTX2) post-ST. EEG and EMG recordings were scored for non-rapid eye movement sleep (NREM), rapid eye movement sleep (REM) and wakefulness. The rats were separated into 4 groups: Vehicle-vulnerable (Veh-Vul; n = 10), Veh-resilient (Veh-Res; n = 11), ANT-vulnerable (ANT-Vul; n = 8) and ANT-resilient (ANT-Res; n = 8) based on whether, compared to baseline, the rats showed a decrease or no change/increase in REM during the first 4 h following ST. Post-ST ANT microinjected into BLA attenuated the fear-conditioned reduction in REM in ANT-Vul rats on CTX1, but did not significantly alter REM in ANT-Res rats. However, compared to Veh treated rats, REM was reduced in ANT treated rats on CTX2. There were no group differences in freezing or SIH across conditions. Therefore, CRFR1 in BLA plays a role in mediating individual differences in sleep responses to stress and in the extinction of fear conditioned changes in sleep.

Impulsive responding in threat and reward contexts as a function of PTSD symptoms and trait disinhibition

We examined current posttraumatic stress disorder (PTSD) symptoms, trait disinhibition, and affective context as contributors to impulsive and self-destructive behavior in 94 trauma-exposed Veterans. Participants completed an affective Go/No-Go task (GNG) with different emotional contexts (threat, reward, and a multidimensional threat/reward condition) and current PTSD, trait disinhibition, and risky/self-destructive behavior measures. PTSD interacted with trait disinhibition to explain recent engagement in risky/self-destructive behavior, with Veterans scoring high on trait disinhibition and current PTSD symptoms reporting the highest levels of these behaviors. On the GNG task, commission errors were also associated with the interaction of PTSD symptoms and trait disinhibition. Specifically, PTSD symptoms were associated with greater commission errors in threat vs. reward contexts for individuals who were low on trait disinhibition. In contrast, veterans high on PTSD and trait disinhibition exhibited the greatest number of commission errors in the multidimensional affective context that involved both threat and reward processing. Results highlight the interactive effects of PTSD and disinhibited personality traits, as well as threat and reward systems, as risk factors for impulsive and self-destructive behavior in trauma-exposed groups. Findings have clinical implications for understanding heterogeneity in the expression of PTSD and its association with disinhibited behavior.

Functional Neuroanatomy of Emotion and Its Regulation in PTSD

Posttraumatic stress disorder (PTSD) is a devastating disorder, linked to profound mental, physical, occupational, and functional impairment. In addition, it is a highly complex disorder, characterized by symptom heterogeneity across multiple domains. Nevertheless, emotion dysregulation arising from the exaggerated response to threat or from the inability to regulate negative emotional states plays a defining role in the pathophysiology of PTSD. In order to improve our understanding of how emotion dysregulation manifests in this illness, functional neuroimaging research over the past 20 years provides great insight into underlying neuroanatomy of each component of emotion dysregulation in the context of PTSD. While prior reviews exist on the topic of neuroimaging findings in PTSD, the present review synthesizes that work through the lens of emotion and its regulation. Studies that employed tasks of emotional responding and symptom provocation, implicit regulation (e.g., emotional Stroop and interference), explicit regulation (e.g., cognitive reappraisal), and fear conditioning/extinction were reviewed. Findings demonstrate that emotion dysregulation in PTSD arises from complications within a large neurocircuitry involving the amygdala, insula, hippocampus, anterior cingulate cortex, and prefrontal cortex. Although an exaggerated response in the amygdala and insula to negative emotional triggers is pervasive, PTSD is also marked by deficient appraisal, resolution, and management of negative emotional states subserved by the anterior cingulate cortex and prefrontal cortex during regulation. These findings further support the importance of studying emotion-regulation deficits in tandem with exaggerated symptom provocation in order to better understand the constellation of symptoms present in those with PTSD.

Single-Prolonged Stress: A Review of Two Decades of Progress in a Rodent Model of Post-traumatic Stress Disorder

Post-traumatic stress disorder (PTSD) is a common, costly, and often debilitating psychiatric condition. However, the biological mechanisms underlying this disease are still largely unknown or poorly understood. Considerable evidence indicates that PTSD results from dysfunction in highly-conserved brain systems involved in stress, anxiety, fear, and reward. Pre-clinical models of traumatic stress exposure are critical in defining the neurobiological mechanisms of PTSD, which will ultimately aid in the development of new treatments for PTSD. Single prolonged stress (SPS) is a pre-clinical model that displays behavioral, molecular, and physiological alterations that recapitulate many of the same alterations observed in PTSD, illustrating its validity and giving it utility as a model for investigating post-traumatic adaptations and pre-trauma risk and protective factors. In this manuscript, we review the present state of research using the SPS model, with the goals of (1) describing the utility of the SPS model as a tool for investigating post-trauma adaptations, (2) relating findings using the SPS model to findings in patients with PTSD, and (3) indicating research gaps and strategies to address them in order to improve our understanding of the pathophysiology of PTSD.

Age As Moderator of Emotional Stroop Task Performance in Posttraumatic Stress Disorder (PTSD)

Emotional Stroop task (EST) has been extensively used to investigate attentional processes in posttraumatic stress disorder (PTSD). Even though aging significantly changes the dynamics of emotion-cognition interactions, very little is known about its role in shaping EST performance in PTSD patients. In the present study we tested a uniquely large sample of motor vehicle accident victims. Data of 194 participants (75.3% female; mean age = 36.64 years, SD = 12.3) were included in the analysis, out of which 136 (70.1%) were diagnosed with PTSD. Prior to the psychiatric assessment, participants completed the pictorial version of EST (neutral, positive, negative, and accidents photos were presented). Comparison of the PTSD and control groups revealed a specific increase in reaction times (RTs) related to the exposure of trauma-related material. At the same time, previously unreported, moderating effects of age were also discovered. Older participants, in contrast to the younger group, showed no increase in RTs and interference scores in trials where accident photos were presented. Our study points to the key role of age as a previously understudied factor modifying EST performance in PTSD patients.

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.

Performance in a blocked versus randomized emotional Stroop task in an aged, early traumatized group with and without posttraumatic stress symptoms

BACKGROUND AND OBJECTIVES

Attentional biases (AB) for trauma-related stimuli have been examined in many studies assessing different trauma samples. In emotional Stroop tasks (EST), blocked and single-trial formats are used almost interchangeably in clinical research. There is reason to believe that different designs yield different results and assess different processes, which, however, has been hardly examined in studies. Furthermore, there is a dearth of information about AB in older trauma survivors with posttraumatic stress symptoms.

METHODS

Older adults with (n = 20) and without PTSD symptoms (n = 26) as well as non-traumatized controls (n = 21) completed an EST, in which words were presented both blocked and randomized.

RESULTS

Analyses revealed that individuals with PTSD symptoms showed AB for trauma- and depression-related words; however, mode of administration did not significantly influence reaction times.

LIMITATIONS

The emotional Stroop task cannot disentangle the underlying cognitive mechanism (i.e., facilitation, interference, avoidance).

CONCLUSIONS

PTSD symptoms in older trauma survivors are associated with AB. Overall, participants with PTSD symptoms did not show greater impairment of cognitive control in comparison to both control groups. Results also illustrate that methodological differences between task versions need to be considered more thoroughly.

Circuit dysregulation and circuit-based treatments in posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is a psychiatric disorder that develops in some individuals in the aftermath of exposure to traumatic events, such as actual or threatened death, serious injury or sexual assault. It has been hypothesized that dysregulations in a number of specific neurocircuits, characterized by heightened responsivity of amygdala, dACC and insula, diminished responsivity of mPFC, impaired hippocampal function and deficits in cortical regions, underlie the development and expression of key PTSD symptoms. Here, we concisely describe three functional neural circuits implicated in PTSD pathophysiology and briefly review selected treatment strategies in the context of these neural circuits. We start with the commonly implicated neurocircuit model, namely, the fear learning and threat detection circuits, and then discuss the context processing circuitry, which plays an important role among others, in fear regulation. We then discuss the emotion regulation circuitry, which can further contribute to PTSD pathophysiology, and conclude with a discussion of the therapeutic approaches that might be targeting dysregulation in these circuits in PTSD patients. Specifically, we discuss how exposure-based treatments might be targeting fear learning circuits, and the pharmacological and brain-stimulation interventions aimed to augment these therapies. Finally, we discuss other pharmacological and cognitive therapeutic approaches that can augment or restore the function of the context processing and emotional regulation circuits.

The basolateral amygdala can mediate the effects of fear memory on sleep independently of fear behavior and the peripheral stress response

Fear conditioning associated with inescapable shock training (ST) and fearful context re-exposure (CR) alone can produce significant behavioral fear, a stress response and alterations in subsequent REM sleep. These alterations may vary among animals and are mediated by the basolateral nucleus of the amygdala (BLA). Here, we used the GABA_A agonist, muscimol (Mus), to inactivate BLA prior to CR and examined the effects on sleep, freezing and stress-induced hyperthermia (SIH). Wistar rats (n=28) were implanted with electrodes for recording sleep, data loggers for recording core body temperature, and with cannulae aimed bilaterally into BLA. After recovery, the animals were habituated to the injection procedure and baseline sleep was recorded. On experimental day 1, rats received ST (20 footshocks, 0.8mA, 0.5s duration, 60s interstimulus interval). On experimental day 7, the rats received microinjections (0.5μl) into BLA of either Mus (1.0μM; n=13) or vehicle (Veh; n=15) prior to CR (CR1). On experimental day 21, the animals experienced a second CR (CR2) without Mus. For analysis, the rats were separated into 4 groups: (Veh-vulnerable (Veh-Vul; n=8), Veh-resilient (Veh-Res; n=7), Mus-vulnerable (Mus-Vul; n=7), and Mus-resilient (Mus-Res; n=6)) based on whether or not REM was decreased, compared to baseline, during the first 4h following ST. Pre-CR1 inactivation of BLA did not alter freezing or SIH, but did block the reduction in REM in the Mus-Vul group compared to the Veh-Vul group. These data indicate that BLA is an important region for mediating the effects of fearful memories on sleep.

Individual Differences in Animal Stress Models: Considering Resilience, Vulnerability, and the Amygdala in Mediating the Effects of Stress and Conditioned Fear on Sleep

STUDY OBJECTIVES

To examine the REM sleep response to stress and fearful memories as a potential marker of stress resilience and vulnerability and to assess the role of the basolateral amygdala (BLA) in mediating the effects of fear memory on sleep.

METHODS

Outbred Wistar rats were surgically implanted with electrodes for recording EEG and EMG and with bilateral guide cannulae directed at the BLA. Data loggers were placed intraperitoneally to record core body temperature. After recovery from surgery, the rats received shock training (ST: 20 footshocks, 0.8 mA, 0.5-s duration, 60-s interstimulus interval) and afterwards received microinjections of the GABAA agonist muscimol (MUS; 1.0 μM) to inactivate BLA or microinjections of vehicle (VEH) alone. Subsequently, the rats were separated into 4 groups (VEH-vulnerable (VEH-Vul; n = 14), VEH-resilient (VEH-Res; n = 13), MUS-vulnerable (MUS-Vul; n = 8), and MUS-resilient (MUS-Res; n = 11) based on whether or not REM was decreased, compared to baseline, during the first 4 h following ST. We then compared sleep, freezing, and the stress response (stress-induced hyperthermia, SIH) across groups to determine the effects of ST and fearful context re-exposure alone (CTX).

RESULTS

REM was significantly reduced on the ST day in both VEH-Vul and MUS-Vul rats; however, post-ST MUS blocked the reduction in REM on the CTX day in the MUS-Vul group. The VEH-Res and MUS-Res rats showed similar levels of REM on both ST and CTX days. The effects of post-ST inactivation of BLA on freezing and SIH were minimal.

CONCLUSIONS

Outbred Wistar rats can show significant individual differences in the effects of stress on REM that are mediated by BLA. These differences in REM can be independent of behavioral fear and the peripheral stress response, and may be an important biomarker of stress resilience and vulnerability.

Distinction in EEG slow oscillations between chronic mild traumatic brain injury and PTSD

Spectral information from resting state EEG is altered in acute mild traumatic brain injury (mTBI) and in disorders of consciousness, but there is disagreement about whether mTBI can elicit long term changes in the spectral profile. Even when identified, any long-term changes attributed to TBI can be confounded by psychiatric comorbidities such as PTSD, particularly for combat-related mTBI where postdeployment distress is commonplace. To address this question, we measured spectral power during the resting state in a large sample of service members and Veterans varying in mTBI history and active PTSD diagnosis but matched for having had combat blast exposure. We found that PTSD was associated with decreases in low frequency power, especially in the right temporoparietal region, while conversely, blast-related mTBI was associated with increases in low frequency power, especially in prefrontal and right temporal areas. Results support the idea that long-term neurophysiological effects of mTBI share some features with states of reduced arousal and cognitive dysfunction, suggesting a role for EEG in tracking the trajectory of recovery and persisting vulnerabilities to injury. Additionally, results suggest that EEG power reflects distinct pathophysiologies for current PTSD and chronic mTBI.

Altered gene expression of the innate immune, neuroendocrine, and nuclear factor-kappa B (NF-κB) systems is associated with posttraumatic stress disorder in military personnel

Whole transcriptome analysis provides an unbiased examination of biological activity, and likely, unique insight into the mechanisms underlying posttraumatic stress disorder (PTSD) and comorbid depression and traumatic brain injury. This study compared gene-expression profiles in military personnel with PTSD (n=28) and matched controls without PTSD (n=27) using HG-U133 Plus 2.0 microarrays (Affymetrix), which contain 54,675 probe sets representing more than 38,500 genes. Analysis of expression profiles revealed 203 differentially expressed genes in PTSD, of which 72% were upregulated. Using Partek Genomics Suite 6.6, differentially expressed transcription clusters were filtered based on a selection criterion of ≥1.5 relative fold change at a false discovery rate of ≤5%. Ingenuity Pathway Analysis (Qiagen) of the differentially expressed genes indicated a dysregulation of genes associated with the innate immune, neuroendocrine, and NF-κB systems. These findings provide novel insights that may lead to new pharmaceutical agents for PTSD treatments and help mitigate mental and physical comorbidity risk.

Conditional and indirect effects of age of first exposure on PTSD symptoms

Childhood violence exposure (CVE) in formative developmental years may have potent effects on severity and complexity of post-traumatic stress symptoms (PTSS) in adulthood, yet little research has examined the role of age of first exposure in the context of polyvictimization or gone beyond an examination of direct effects. The current study examines the specific associations between age of first exposure, total CVE, and posttraumatic stress symptoms in adulthood. Further, the conditional and indirect effects of age of first exposure on posttraumatic stress symptoms were examined. We hypothesized that age of first exposure to violence would be associated with higher total violence exposure across childhood, thereby predicting current posttraumatic stress symptom severity (i.e., indirect effect). We also postulated that age of first exposure would affect the relationship between total violence exposure and posttraumatic stress symptoms such that earlier exposure would exacerbate the effects of violence exposure (i.e., conditional effect). Participants included 269 violence-exposed adults recruited through MTurk; the mean age of first CVE was 6 years (SD=3.29). Conditional process models indicated that age of first exposure was significantly associated with higher total childhood violence exposure, which in turn, was significantly associated with current posttraumatic stress symptoms in all domains. Further, a conditional effect of age of first exposure was present such that the relationship between total exposure to violence and symptoms of hyperarousal was stronger for those first exposed at earlier ages. Findings provide support suggesting the particular potency of early trauma on regulatory response systems.

Magnetic Resonance Therapy Improves Clinical Phenotype and EEG Alpha Power in Posttraumatic Stress Disorder

Background:

Posttraumatic stress disorder (PTSD) is a disabling and prevalent psychiatric disorder with limited effective treatment options. In addition to the clinical features of the disease, pathologic changes in the electroencephalogram (EEG), including decreased alpha power, have been reported.

Objectives:

To determine if magnetic brain stimulation can induce normalization of EEG abnormalities and improve clinical symptoms in PTSD in a preliminary, open-label evaluation.

Materials and Methods:

We reviewed prospectively-collected data on 21 veterans that were consecutively-treated for PTSD. Magnetic resonance therapy (MRT) was administered for two weeks at treatment frequencies based on frequency-domain analysis of each patient’s dominant alpha-band EEG frequencies and resting heart rate. Patients were evaluated on the PTSD checklist (PCL-M) and pre- and post-treatment EEGs before and after MRT.

Results:

Of the 21 patients who initiated therapy, 16 completed treatment. Clinical improvements on the PCL-M were seen in these 16 patients, with an average pre-treatment score of 54.9 and post-treatment score of 31.8 (P < 0.001). In addition, relative global EEG alpha-band (8 - 13 Hz) power increased from 32.0 to 38.5 percent (P = 0.013), and EEG delta-band (1 - 4 Hz) power decreased from 32.3 percent to 26.8 percent (P = 0.028).

Conclusions:

These open-label data show trends toward normalization of EEG and concomitant clinical improvement using magnetic stimulation for PTSD.

Epigenetics and memory: causes, consequences and treatments for post-traumatic stress disorder and addiction

Understanding the interaction between fear and reward at the circuit and molecular levels has implications for basic scientific approaches to memory and for understanding the etiology of psychiatric disorders. Both stress and exposure to drugs of abuse induce epigenetic changes that result in persistent behavioral changes, some of which may contribute to the formation of a drug addiction or a stress-related psychiatric disorder. Converging evidence suggests that similar behavioral, neurobiological and molecular mechanisms control the extinction of learned fear and drug-seeking responses. This may, in part, account for the fact that individuals with post-traumatic stress disorder have a significantly elevated risk of developing a substance use disorder and have high rates of relapse to drugs of abuse, even after long periods of abstinence. At the behavioral level, a major challenge in treatments is that extinguished behavior is often not persistent, returning with changes in context, the passage of time or exposure to mild stressors. A common goal of treatments is therefore to weaken the ability of stressors to induce relapse. With the discovery of epigenetic mechanisms that create persistent molecular signals, recent work on extinction has focused on how modulating these epigenetic targets can create lasting extinction of fear or drug-seeking behavior. Here, we review recent evidence pointing to common behavioral, systems and epigenetic mechanisms in the regulation of fear and drug seeking. We suggest that targeting these mechanisms in combination with behavioral therapy may promote treatment and weaken stress-induced relapse.

IRE1α-XBP1 Pathway Is Activated Upon Induction of Single-Prolonged Stress in Rat Neurons of the Medial Prefrontal Cortex

Endoplasmic reticulum stress (ERS) is associated with many nervous system diseases. IRElα is considered as ERS sensor that, upon activation, initiates the nonconventional splicing of the precursor unspliced form of X-box binding protein 1 (XBP1u) messenger RNA (mRNA) to yield an active transcription factor-XBP1s. The goal of this study is to detect whether there is activation of IRE1α-XBP1 pathway in the medial prefrontal cortex (mPFC) of posttraumatic stress disorder (PTSD) model rats. This study adopted single-prolonged stress (SPS) model. Behavioral functions including anxiety-like behavior, exploration behavior, and spatial memory were assessed by open field test and Morris water maze test. We detected the IRE1α and XBP1 by using methods of double-labeling immunofluorescence, Western blot, and quantitative real-time reverse transcription-PCR (qRT-PCR). We also observed neuronal apoptosis by transferase-mediated dUTP Nick-end-labeling (TUNEL) staining and the expression of caspase-12 by qRT-PCR. Our results showed that the expression of IRE1α, XBP1u, and total XBP1 significantly increased at 1 day after SPS and then decreased gradually. At the same time, XBP1s appeared and peaked at 4 days after SPS, which indicated that IRE1α-XBP1 pathway was activated upon induction of SPS stimulation. We also noted that the mRNA of caspase-12 was upregulated after SPS. Our study preliminarily showed that ERS mediated by IRE1α-XBP1 pathway was closely related to PTSD and it might be a pathogenesis of PTSD.

A neurobehavioral account for individual differences in resilience to chronic military stress

BACKGROUND

Military training is a chronic stressful period that often induces stress-related psychopathology. Stress vulnerability and resilience depend on personality trait anxiety, attentional threat bias and prefrontal-limbic dysfunction. However, how these neurobehavioral elements interact with regard to the development of symptoms following stress remains unclear.

METHOD

Fifty-five healthy combat soldiers undergoing intensive military training completed functional magnetic resonance imaging (fMRI) testing while performing the dot-probe task (DPT) composed of angry (threat) and neutral faces. Participants were then stratified according to their bias tendency to avoidance (n = 25) or vigilance (n = 30) groups, categorized as high or low trait anxiety and assessed for post-stress symptom severity.

RESULTS

Avoidance compared to vigilance tendency was associated with fewer post-trauma symptoms and increased hippocampal response to threat among high anxious but not low anxious individuals. Importantly, mediation analysis revealed that only among high anxious individuals did hippocampal activity lead to lower levels of symptoms through avoidance bias tendency. However, in the whole group, avoidance bias was modulated by the interplay between the hippocampus and the dorsal anterior cingulate cortex (dACC).

CONCLUSIONS

Our results provide a neurobehavioral model to explain the resilience to post-trauma symptoms following chronic exposure. The model points to the importance of considering threat bias tendency in addition to personality traits when investigating the brain response and symptoms of trauma. Such a multi-parametric approach that accounts for individual behavioral sensitivities may also improve brain-driven treatments of anxiety, possibly by targeting the interplay between the hippocampus and the dACC.

Neural circuits in anxiety and stress disorders: a focused review

Anxiety and stress disorders are among the most prevalent neuropsychiatric disorders. In recent years, multiple studies have examined brain regions and networks involved in anxiety symptomatology in an effort to better understand the mechanisms involved and to develop more effective treatments. However, much remains unknown regarding the specific abnormalities and interactions between networks of regions underlying anxiety disorder presentations. We examined recent neuroimaging literature that aims to identify neural mechanisms underlying anxiety, searching for patterns of neural dysfunction that might be specific to different anxiety disorder categories. Across different anxiety and stress disorders, patterns of hyperactivation in emotion-generating regions and hypoactivation in prefrontal/regulatory regions are common in the literature. Interestingly, evidence of differential patterns is also emerging, such that within a spectrum of disorders ranging from more fear-based to more anxiety-based, greater involvement of emotion-generating regions is reported in panic disorder and specific phobia, and greater involvement of prefrontal regions is reported in generalized anxiety disorder and posttraumatic stress disorder. We summarize the pertinent literature and suggest areas for continued investigation.

On the Road to Translation for PTSD Treatment: Theoretical and Practical Considerations of the Use of Human Models of Conditioned Fear for Drug Development

The use of quantitative, laboratory-based measures of threat in humans for proof-of-concept studies and target development for novel drug discovery has grown tremendously in the last 2 decades. In particular, in the field of posttraumatic stress disorder (PTSD), human models of fear conditioning have been critical in shaping our theoretical understanding of fear processes and importantly, validating findings from animal models of the neural substrates and signaling pathways required for these complex processes. Here, we will review the use of laboratory-based measures of fear processes in humans including cued and contextual conditioning, generalization, extinction, reconsolidation, and reinstatement to develop novel drug treatments for PTSD. We will primarily focus on recent advances in using behavioral and physiological measures of fear, discussing their sensitivity as biobehavioral markers of PTSD symptoms, their response to known and novel PTSD treatments, and in the case of d-cycloserine, how well these findings have translated to outcomes in clinical trials. We will highlight some gaps in the literature and needs for future research, discuss benefits and limitations of these outcome measures in designing proof-of-concept trials, and offer practical guidelines on design and interpretation when using these fear models for drug discovery.

Sex differences in extinction recall in posttraumatic stress disorder: a pilot fMRI study

Recent research has found that individuals with posttraumatic stress disorder (PTSD) exhibit an impaired memory of fear extinction compounded by deficient functional activation of key nodes of the fear network including the amygdala, hippocampus, ventromedial prefrontal cortex (vmPFC) and dorsal anterior cingulate cortex (dACC). Research has shown these regions are sexually dimorphic and activate differentially in healthy men and women during fear learning tasks. To explore biological markers of sex differences following exposure to psychological trauma, we used a fear learning and extinction paradigm together with functional magnetic resonance imaging (fMRI) and skin conductance response (SCR) to assess 31 individuals with PTSD (18 women; 13 men) and 25 matched trauma-exposed healthy control subjects (13 women; 12 men). Whereas no sex differences appeared within the trauma-exposed healthy control group, both psychophysiological and neural activation patterns within the PTSD group indicated deficient recall of extinction memory among men and not among women. Men with PTSD exhibited increased activation in the left rostral dACC during extinction recall compared with women with PTSD. These findings highlight the importance of tracking sex differences in fear extinction when characterizing the underlying neurobiological mechanisms of PTSD psychopathology.