Neural correlates of emotional reactivity and regulation associated with treatment response in a randomized clinical trial for posttraumatic stress disorder

Neural correlates and plasticity of explicit emotion regulation following the experience of trauma

Experiencing trauma or other adverse life events is highly prevalent and poses a significant risk for the development of mental disorders. Understanding the underlying mechanisms and neural processes involved in trauma processing is crucial for both prevention and targeting symptoms. Especially, difficulties in emotion regulation emerge as one key mechanism implicated in the development of conditions such as post-traumatic stress disorder (PTSD) following traumatic experiences. However, neural correlates of explicit emotion regulation among individuals who have undergone trauma have not received much attention. Understanding the neural basis of dysregulated emotion following trauma could reveal important details about how trauma interferes with emotional regulation systems, informing the development of more specific intervention approaches. Therefore, this mini review summarizes current research, and identifies relevant gaps in the literature and challenges for future studies. Specifically, it provides an overview of the neural dysregulation associated with explicit emotion regulation strategies such as reappraisal or suppression. Finally, it highlights promising findings from intervention studies targeting emotion regulation, such as trauma-focused exposure therapy and neurofeedback, indicating neural plasticity in individuals with traumatic experiences. Hereby, this review aims to bridge the gap between fundamental and intervention research and highlights future directions for translational research.

Fears Worth Testing Out: A Systematic Review of the Neural Mechanisms of Treatment Outcome for Anxiety-Related Disorders

With the advent of human neuroimaging, researchers were drawn to the idea that by better understanding the human brain, more effective mental health interventions could be developed. It has been more than 20 years since the first functional magnetic resonance imaging (fMRI) studies were conducted to examine changes in brain activation with anxiety-related treatments and more than 60 studies have since been published in this vein. For the current review, we conduct a systematic review of this literature, focusing on adult studies using task-based fMRI to measure brain activation changes with pharmacologic or psychotherapy interventions for phobia, social anxiety disorder, panic disorder, generalized anxiety disorder, posttraumatic stress disorder, and obsessive-compulsive disorder. Neuroscientific theories of anxiety-related disorders and their treatment have focused on prefrontal-insula-amygdala networks. Treatment-related decreases in amygdala and/or anterior insula activation were identified as the most consistent finding across disorders, with the most consistent results reported for specific phobia. Directionality of change and specific regions implicated in the prefrontal cortex were inconsistent across studies. The potential importance for probing other networks and processes as mechanisms of anxiety treatment was recognized, such as striatal regions underlying inhibitory learning or reward responsivity. Future treatment-fMRI research related to anxiety disorders would benefit from larger sample sizes, use of more nuanced computational approaches, and increased focus on replication. There is continued promise that fMRI research will enhance our understanding of how treatments work and inform the evolution of more effective or personalized mental health treatment.

A framework for a brain-derived nosology of psychiatric disorders

Current psychiatric diagnoses are not defined by neurobiological measures which hinders the development of therapies targeting mechanisms underlying mental illness 1,2 . Research confined to diagnostic boundaries yields heterogeneous biological results, whereas transdiagnostic studies often investigate individual symptoms in isolation. There is currently no paradigm available to comprehensively investigate the relationship between different clinical symptoms, individual disorders, and the underlying neurobiological mechanisms. Here, we propose a framework that groups clinical symptoms derived from ICD-10/DSM-V according to shared brain mechanisms defined by brain structure, function, and connectivity. The reassembly of existing ICD-10/DSM-5 symptoms reveal six cross-diagnostic psychopathology scores related to mania symptoms, depressive symptoms, anxiety symptoms, stress symptoms, eating pathology, and fear symptoms. They were consistently associated with multimodal neuroimaging components in the training sample of young adults aged 23, the independent test sample aged 23, participants aged 14 and 19 years, and in psychiatric patients. The identification of symptom groups of mental illness robustly defined by precisely characterized brain mechanisms enables the development of a psychiatric nosology based upon quantifiable neurobiological measures. As the identified symptom groups align well with existing diagnostic categories, our framework is directly applicable to clinical research and patient care.

Greater Early Posttrauma Activation in the Right Inferior Frontal Gyrus Predicts Recovery From Posttraumatic Stress Disorder Symptoms

BACKGROUND

Posttraumatic stress disorder (PTSD) has been associated with altered emotion processing and modulation in specific brain regions, i.e., the amygdala, insula, and medial prefrontal and anterior cingulate cortices. Functional alterations in these regions, recorded shortly after trauma exposure, may predict changes in PTSD symptoms.

METHODS

Survivors (N = 104) of a traumatic event, predominantly a motor vehicle accident, were included. Functional magnetic resonance imaging was used to assess brain activation 1, 6, and 14 months after trauma exposure (T1, T2, and T3, respectively). Participants performed the Shifted-attention Emotional Appraisal Task, which probes 3 affective processes: implicit emotional processing (of emotional faces), emotion modulation by attention shifting (away from these faces), and emotion modulation by appraisal (of the participants' own emotional response to these faces). We defined regions of interest based on task-related activations, extracted beta weights from these regions of interest, and submitted them to a series of analyses to examine relationships between neural activation and PTSD severity over the 3 time points.

RESULTS

At T1, a regression model containing activations in the left dorsolateral prefrontal cortex, bilateral inferior frontal gyrus (IFG), and medial prefrontal cortex during emotion modulation by appraisal significantly predicted change in PTSD symptoms. More specifically, greater right IFG activation at T1 was associated with greater reduction in symptom severity (T1-T3). Exploratory analysis also found that activation of the right IFG increased from T1 to T3.

CONCLUSIONS

The results suggest that greater early posttrauma activation during emotion appraisal in the right IFG, a region previously linked to cognitive control in PTSD, predicts recovery from PTSD symptoms.

Towards assessing subcortical "deep brain" biomarkers of PTSD with functional near-infrared spectroscopy

Assessment of brain function with functional near-infrared spectroscopy (fNIRS) is limited to the outer regions of the cortex. Previously, we demonstrated the feasibility of inferring activity in subcortical "deep brain" regions using cortical functional magnetic resonance imaging (fMRI) and fNIRS activity in healthy adults. Access to subcortical regions subserving emotion and arousal using affordable and portable fNIRS is likely to be transformative for clinical diagnostic and treatment planning. Here, we validate the feasibility of inferring activity in subcortical regions that are central to the pathophysiology of posttraumatic stress disorder (PTSD; i.e. amygdala and hippocampus) using cortical fMRI and simulated fNIRS activity in a sample of adolescents diagnosed with PTSD (N = 20, mean age = 15.3 ± 1.9 years) and age-matched healthy controls (N = 20, mean age = 14.5 ± 2.0 years) as they performed a facial expression task. We tested different prediction models, including linear regression, a multilayer perceptron neural network, and a k-nearest neighbors model. Inference of subcortical fMRI activity with cortical fMRI showed high prediction performance for the amygdala (r > 0.91) and hippocampus (r > 0.95) in both groups. Using fNIRS simulated data, relatively high prediction performance for deep brain regions was maintained in healthy controls (r > 0.79), as well as in youths with PTSD (r > 0.75). The linear regression and neural network models provided the best predictions.

Change in posttraumatic stress disorder-related thoughts during treatment: Do thoughts drive change when pills are involved?

Posttraumatic negative thoughts about one's self and the world are related to posttraumatic stress disorder (PTSD) symptom severity and change in cognitive behavioral treatment (CBT), but little is known about this association when CBT is delivered with medication. The current study presents a planned comparison of changes in negative posttraumatic thoughts during (a) prolonged exposure (PE) plus pill placebo (PE+PLB), (b) sertraline plus enhanced medication management (SERT+EMM), and (c) PE plus sertraline (PE+SERT) as part of a randomized clinical trial in a sample of 176 veterans. Lagged regression modeling revealed that change in posttraumatic negative thoughts was associated with PTSD symptom change in the conditions in which participants received sertraline, ds = 0.14-0.25, ps = 0.04-.001). However, contrary to previous research, the models that started with symptom change were also statistically significant, d = 0.23, p < .001, for the lagged effect of symptoms on negative thoughts about self in the SERT+EMM condition, indicating a bidirectional association between such thoughts and PTSD symptoms. In the PE+PLB condition, no significant association between posttraumatic thoughts and PTSD symptoms emerged in either direction. These results suggest that the previously demonstrated role of change in posttraumatic thoughts leading to PTSD symptom reduction in PE may be altered when combined with pill administration, either active or placebo.

Investigating pupillometry to detect emotional regulation difficulties in post-traumatic stress disorder

OBJECTIVE

Individuals with posttraumatic stress disorder (PTSD) have been found to exhibit emotional regulation difficulties. However, the specific neural mechanisms that underlie these difficulties remain understudied. This study aimed to use pupillometry as an index function of parasympathetic nervous system activation, to investigate the mechanisms underlying emotional regulation difficulties in individuals with PTSD.

METHOD

A total of 87 trauma-exposed mothers (34 with PTSD and 53 non-PTSD controls) completed an eye tracking assessment in which pupillary dilation in response to emotionally valenced stimuli was measured. The participants also completed two self-report measures of emotional regulation, namely the Difficulties in Emotional Regulation Scale and the Emotional Regulations Questionnaire. Linear mixed-effect modelling was used to assess potential group differences.

RESULTS

The PTSD group exhibited increased pupillary dilation to positively valenced stimuli compared to the non-PTSD group. However, no significant associations between the self-report measures and pupillary response to emotionally valenced stimuli were found.

CONCLUSION

Increased pupillary dilation in PTSD may reflect impaired parasympathetic nervous system processes. The lack of association of these measures with self-reported emotion regulation may suggest reporting biases. Larger studies with more generalised populations are required to consolidate these preliminary findings.

Effects of intranasal oxytocin on threat- and reward-related functional connectivity in men and women with and without childhood abuse-related PTSD

Novel treatments that target neurobiological alterations associated with childhood trauma, particularly among those with posttraumatic stress disorder (PTSD), could mitigate negative outcomes for these at-risk individuals. PTSD is characterized by abnormalities within the brain's salience network and reward circuitry, which are modulated by intranasal oxytocin. Using a double-blind, randomized, placebo-controlled crossover design, we tested whether intranasal oxytocin (24 international units) influenced functional coupling of the amygdala with the anterior insula (AI), dorsal anterior cingulate cortex, and nucleus accumbens in response to implicitly presented fearful, angry, and happy faces among childhood trauma-exposed individuals with (n = 16, 9 women) and without PTSD (n = 18, 12 women). Psychophysiological interaction analyses revealed that oxytocin effects were limited to amygdala-AI connectivity in the fear condition, distinct for men and women, and not impacted by PTSD diagnosis. In response to fear faces, oxytocin reduced left amygdala-left AI connectivity for women but not men; reduced left amygdala-right AI connectivity among women, but increased this connectivity in men; and reduced right amygdala-right anterior insula connectivity for men, but increased it for women. Results suggest that intranasal oxytocin modulates threat salience among childhood trauma-exposed individuals and that these effects vary as a function of gender and hemisphere.

Association of Brain-Derived Neurotrophic Factor rs6265 G>A polymorphism and Post-traumatic Stress Disorder susceptibility: A systematic review and meta-analysis

BACKGROUND

Previous studies have shown that the brain-derived neurotrophic factor (BDNF) rs6265 G > A polymorphism is closely related post-traumatic stress disorder (PTSD) risk. However, the results were not consistent. We therefore conducted a meta-analysis to explore the underlying relationships between BDNF rs6265 G > A polymorphism and PTSD risk.

MATERIALS AND METHODS

Five online databases were searched, and all related studies were reviewed up to July 1, 2020. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were calculated to examine the statistical power of each genetic model. In addition, heterogeneity, sensitivity accumulative analysis, and publication bias were examined to check the statistical power.

RESULT

Overall, 16 publications involving 5,369 subjects were included in this systematic review and 11 case-control studies were analyses in meta-analysis. The pooled results indicated an increasing risk of A allele mutations with PTSD risk. Moreover, the sequential subgroup analysis also demonstrated some similar situations in Asian populations and other groups.

CONCLUSION

Current meta-analysis suggests that the BDNF rs6265 G > A polymorphism might be involved in PTSD susceptibility.

Defining focal brain stimulation targets for PTSD using neuroimaging

INTRODUCTION

Focal brain stimulation has potential as a treatment for posttraumatic stress disorder (PTSD). In this review, we aim to inform selection of focal brain stimulation targets for treating PTSD by examining studies of the functional neuroanatomy of PTSD and treatment response. We first briefly review data on brain stimulation interventions for PTSD. Although published data suggest good efficacy overall, the neurobiological rationale for each stimulation target is not always clear.

METHODS

Therefore, we assess pre- and post-treatment (predominantly psychotherapy) functional neuroimaging studies in PTSD to determine which brain changes seem critical to treatment response. Results of these studies are presented within a previously proposed functional neural systems model of PTSD.

RESULTS

While not completely consistent, research suggests that downregulating the fear learning and threat and salience detection circuits (i.e., amygdala, dorsal anterior cingulate cortex and insula) and upregulating the emotion regulation and executive function and contextual processing circuits (i.e., prefrontal cortical regions and hippocampus) may mediate PTSD treatment response.

CONCLUSION

This literature review provides some justification for current focal brain stimulation targets. However, the examination of treatment effects on neural networks is limited, and studies that include the stimulation targets are lacking. Further, additional targets, such as the cingulate, medial prefrontal cortex, and inferior parietal lobe, may also be worth investigation, especially when considering how to achieve network level changes. Additional research combining PTSD treatment with functional neuroimaging will help move the field forward by identifying and validating novel targets, providing better rationale for specific treatment parameters and personalizing treatment for PTSD.

Neural affective mechanisms associated with treatment responsiveness in veterans with PTSD and comorbid alcohol use disorder

Post-traumatic stress disorder (PTSD) is associated with neuro-physiological abnormalities reflecting increased anticipatory anxiety and reactivity to traumatic cues. It remains unclear whether neural mechanisms associated with PTSD treatment responsiveness, i.e. hyperactivation of the affective salience network in the brain, extend to a comorbid PTSD and substance use disorder population. Thirty-one Veterans with PTSD and co-occurring alcohol use disorder (AUD) were randomly assigned to either prolonged exposure or a non-exposure based treatment. They completed an affective anticipation task while undergoing fMRI, immediately prior and after completing treatment. After controlling for type and length of treatment, larger reduction of PTSD symptoms was associated with decreased anticipatory activation to negative trauma-related cues in the right pre-Supplementary Motor Area (pre-SMA), a region associated with emotion regulation. Smaller reduction in PTSD severity was associated with enhanced anticipatory activation to those cues within the right para-hippocampal region, an affective processing region. Our findings suggest that post-treatment reductions in anticipatory reactivity to trauma-related cues in the pre-SMA and para-hippocampal area are associated with larger PTSD symptom reduction in individuals with co-occurring PTSD and AUD. These results may offer neurofeedback training targets as an alternative to or enhancement of other PTSD treatment modalities in this population.

Associations between resting-state functional connectivity and treatment response in a randomized clinical trial for posttraumatic stress disorder

BACKGROUND

Alterations in resting-state functional connectivity (rsFC) have been reported in posttraumatic stress disorder (PTSD). Here, we examined pre- and post-treatment rsFC during a randomized clinical trial to characterize alterations and examine predictors of treatment response.

METHODS

Sixty-four combat veterans with PTSD were randomly assigned to prolonged exposure (PE) plus placebo, sertraline plus enhanced medication management, or PE plus sertraline. Symptom assessment and resting-state functional magnetic resonance imaging (fMRI) scans occurred before and after treatment. Twenty-nine trauma-exposed combat veterans without PTSD served as a control group at intake. Seed-based and region of interest (ROI)-to-ROI connectivities, as well as an exploratory connectome-based approach were used to analyze rsFC patterns. Based on previously reported findings, analyses focused on Salience Network (SN) and Default-Mode Network (DMN).

RESULTS

At intake, patients with PTSD showed greater DMN-dorsal attention network (DAN) connectivity (between ventromedial prefrontal cortex and superior parietal lobule; family-wise error corrected p = .011), greater SN-DAN connectivity (between insula and middle frontal gyrus; corrected p = .003), and a negative correlation between re-experiencing symptoms and within-DMN connectivity (between posterior cingulate cortex (PCC) and middle temporal gyrus; corrected p < .001). We also found preliminary evidence for associations between rsFC and treatment response. Specifically, high responders (≥50% PTSD symptom improvement), compared with low responders, had greater SN-DMN segregation (i.e., less pre-treatment amygdala-PCC connectivity; p = .011) and lower pre-treatment global centrality (p = .042).

CONCLUSIONS

Our findings suggest neural abnormalities in PTSD and may inform future research examining neural biomarkers of PTSD treatment response.

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.