Facilitating Fear-Based Memory Extinction With Dexamethasone: A Randomized Controlled Trial in Male Veterans With Combat-Related PTSD

The role of cortisol in development and treatment of PTSD among service members: A narrative review

Posttraumatic stress disorder (PTSD) is a pervasive issue within military populations, with approximately 29 % of post-9/11 service members experience PTSD at some point in their lifetime. One potentially important factor in PTSD development and treatment response is dysregulation of the stress response system stemming from exposure to multiple traumas and sustained operational stress associated with military training and deployment. In particular, the end-product of the hypothalamic-pituitary-adrenal (HPA) axis, cortisol, is of particular interest to researchers examining physiological stress response in the context of mental health. Research exploring cortisol has been ongoing for decades, both to further understand its pathways and mechanisms, and to develop potential novel PTSD treatments. This paper provides a narrative review of some of the published literature examining cortisol's role in PTSD as a potential factor in development, maintenance, and treatment augmentation, with emphasis on military populations. The results of this review highlight the importance of exploring alterations to the stress response system, and cortisol in particular, for the evaluation and treatment of PTSD in the military, the need for more comprehensive work towards understanding development of these alterations through military training and service, and its impact on long-term PTSD outcomes.

Treatment Approaches for Posttraumatic Stress Disorder Derived From Basic Research on Fear Extinction

This brief review article will describe treatment approaches for posttraumatic stress disorder (PTSD) based on findings from basic research. The focus of this review will be fear conditioning and extinction models, which provide a translational model of PTSD that can help translate basic research in nonhuman animals through well-controlled trials confirming the efficacy of treatment approaches in humans with PTSD such as prolonged exposure therapy. Specific cognitive aspects of fear extinction processes, including consolidation and reconsolidation, are reviewed along with behavioral and pharmacological treatment strategies based on basic research in these areas including attempts to prevent the development of PTSD as well as the treatment of chronic PTSD. Pharmacological, behavioral, and device-based augmentation strategies of PTSD treatment based in basic science findings are reviewed, including those that disrupt noradrenergic receptor processes, medications that act on NMDA receptors, physical exercise, cannabinoids, estradiol, dexamethasone, yohimbine, losartan, dopamine, and MDMA, along with the evidence for their efficacy in human clinical samples. While fear extinction provides an exciting translational opportunity to improve PTSD based on basic science findings, we review limitations and challenges of the extant literature as well as future directions.

Adrenalectomy exacerbates stress-induced impairment in fear discrimination: A causal role for kynurenic acid?

Impaired activity of the hypothalamic-pituitary axis and reduced blood levels of glucocorticoids (GCs) are signature features of stress-related maladies. Recent evidence suggests a possible role of the tryptophan metabolite kynurenic acid (KYNA) in this context. Here we investigated possible causal relationships in adult male rats, using stress-induced fear discrimination as a translationally relevant behavioral outcome measure. One week following adrenalectomy (ADX) or sham surgery, animals were for 2 h either physically restrained or exposed to a predator odor, which caused a much milder stress response. Extracellular KYNA levels were determined before, during and after stress by in vivo microdialysis in the prefrontal cortex. Separate cohorts underwent a fear discrimination procedure starting immediately after stress termination. Different auditory conditioned stimuli (CS) were either paired with a foot shock (CS+) or non-reinforced (CS-). One week later, fear was assessed by re-exposing the animals to each CS. Separate groups of rats were treated with the KYNA synthesis inhibitor BFF-816 prior to stress initiation to test a causal role of KYNA in fear discrimination. Restraint stress raised extracellular KYNA levels by ∼85 % in ADX rats for several hours, and these animals were unable to discriminate between CS+ and CS-. Both effects were prevented by BFF-816 and were not observed after exposure to predator odor or in sham-operated rats. These findings suggest that a causal connection exists between adrenal function, stress-induced KYNA increases, and behavioral deficits. Pharmacological inhibition of KYNA synthesis may therefore be an attractive, novel option for the treatment of stress-related disorders.

Pharmacological memory modulation to augment trauma-focused psychotherapy for PTSD: a systematic review of randomised controlled trials

Trauma-focused psychotherapy (tf-PT) is the first-line treatment for posttraumatic stress disorder (PTSD). Tf-PT focuses on processing and modulating trauma memories. Not all patients benefit, however, and there is room for improvement of efficacy. Pharmacologically augmenting trauma memory modulation in the context of tf-PT may help optimise treatment outcome. To systematically review effects of pharmacologically augmented memory modulation in the context of tf-PT for PTSD (PROSPERO preregistration ID: CRD42021230623). We conducted a systematic review of randomised controlled trials of psychotherapy treatment for PTSD. We included placebo-controlled studies that augmented at least one treatment session pharmacologically targeting memory extinction or reconsolidation. We calculated post-treatment between group (pharmacological augmentation vs placebo control) effect sizes of PTSD symptom severity. We included 13 RCTs. There was large heterogeneity in augmentation procedure and methodological quality. Four studies showed significantly greater PTSD symptom reduction in the pharmacological augmentation group (propranolol, hydrocortisone, dexamethasone, D-cycloserine) compared to placebo. Seven studies showed no significant effect of pharmacological augmentation compared to placebo (D-cycloserine, rapamycin, mifepristone, propranolol, mifepristone combined with D-cycloserine, methylene blue). Two studies showed significantly smaller PTSD symptom reduction in the pharmacological augmentation group (D-cycloserine, dexamethasone) compared to placebo. Results of pharmacological augmentation were mixed overall and heterogenous for the pharmacological agents tested in more than one study. Additional studies and replications are needed to identify which pharmacological agents work, in which combination and to identify patient groups that benefit most to tailor PTSD treatment.

Pharmacological Implications of Adjusting Abnormal Fear Memory: Towards the Treatment of Post-Traumatic Stress Disorder

Post-traumatic stress disorder (PTSD) is a unique clinical mental abnormality presenting a cluster of symptoms in which patients primarily experience flashbacks, nightmares and uncontrollable thoughts about the event that triggered their PTSD. Patients with PTSD may also have comorbid depression and anxiety in an intractable and long-term course, which makes establishing a comprehensive treatment plan difficult and complicated. The present article reviews current pharmacological manipulations for adjusting abnormal fear memory. The roles of the central monoaminergic systems (including serotonin, norepinephrine and dopamine) within the fear circuit areas and the involvement of the hypothalamic-pituitary-adrenal (HPA) axis and glucocorticoid receptor (GR) are explored based on attempts to integrate current clinical and preclinical basic studies. In this review, we explain how these therapeutic paradigms function based on their connections to stages of the abnormal fear memory process from condition to extinction. This may provide useful translational interpretations for clinicians to manage PTSD.

Effects of RU486 in Treatment of Traumatic Stress-Induced Glucocorticoid Dysregulation and Fear-Related Abnormalities: Early versus Late Intervention

Central glucocorticoid receptor (GR) activity is enhanced following traumatic events, playing a key role in the stress-related cognitive abnormalities of posttraumatic stress disorder (PTSD). GR antagonists are expected to have potential as pharmacological agents to treat PTSD-related symptoms such as anxiety and fear memory disruption. However, an incubation period is usually required and stress-induced abnormalities do not develop immediately following the trauma; thus, the optimal intervention timing should be considered. Single prolonged stress (SPS) was employed as a rodent PTSD model to examine the effects of early or late (1–7 versus 8–14 days after the SPS) sub-chronic RU486 (a GR antagonist) administration. Behaviorally, fear conditioning and anxiety behavior were assessed using the fear-conditioning test and elevated T-maze (ETM), respectively. Neurochemically, the expressions of GR, FK506-binding proteins 4 and 5 (FKBP4 and FKBP5), and early growth response-1 (Egr-1) were assessed in the hippocampus, medial prefrontal cortex (mPFC), amygdala, and hypothalamus, together with the level of plasma corticosterone. Early RU486 administration could inhibit SPS-induced behavioral abnormalities and glucocorticoid system dysregulation by reversing the SPS-induced fear extinction deficit, and preventing SPS-reduced plasma corticosterone levels and SPS-induced Egr-1 overexpression in the hippocampus. Early RU486 administration following SPS also increased the FKBP5 level in the hippocampus and hypothalamus. Finally, both early and late RU486 administration inhibited the elevated hippocampal FKBP4 level and hypothalamus GR level in the SPS rats. Early intervention with a GR antagonist aids in the correction of traumatic stress-induced fear and anxiety dysregulation.

Pharmacotherapy for post traumatic stress disorder (PTSD)

BACKGROUND

Posttraumatic stress disorder (PTSD) is a prevalent and disabling disorder. Evidence that PTSD is characterised by specific psychobiological dysfunctions has contributed to a growing interest in the use of medication in its treatment.

OBJECTIVES

To assess the effects of medication for reducing PTSD symptoms in adults with PTSD.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; Issue 11, November 2020); MEDLINE (1946-), Embase (1974-), PsycINFO (1967-) and PTSDPubs (all available years) either directly or via the Cochrane Common Mental Disorders Controlled Trials Register (CCMDCTR). We also searched international trial registers. The date of the latest search was 13 November 2020.

SELECTION CRITERIA

All randomised controlled trials (RCTs) of pharmacotherapy for adults with PTSD.

DATA COLLECTION AND ANALYSIS

Three review authors (TW, JI, and NP) independently assessed RCTs for inclusion in the review, collated trial data, and assessed trial quality. We contacted investigators to obtain missing data. We stratified summary statistics by medication class, and by medication agent for all medications. We calculated dichotomous and continuous measures using a random-effects model, and assessed heterogeneity.

MAIN RESULTS

We include 66 RCTs in the review (range: 13 days to 28 weeks; 7442 participants; age range 18 to 85 years) and 54 in the meta-analysis.  For the primary outcome of treatment response, we found evidence of beneficial effect for selective serotonin reuptake inhibitors (SSRIs) compared with placebo (risk ratio (RR) 0.66, 95% confidence interval (CI) 0.59 to 0.74; 8 studies, 1078 participants), which improved PTSD symptoms in 58% of SSRI participants compared with 35% of placebo participants, based on moderate-certainty evidence.  For this outcome we also found evidence of beneficial effect for the noradrenergic and specific serotonergic antidepressant (NaSSA) mirtazapine: (RR 0.45, 95% CI 0.22 to 0.94; 1 study, 26 participants) in 65% of people on mirtazapine compared with 22% of placebo participants, and for the tricyclic antidepressant (TCA) amitriptyline (RR 0.60, 95% CI 0.38 to 0.96; 1 study, 40 participants) in 50% of amitriptyline participants compared with 17% of placebo participants, which improved PTSD symptoms. These outcomes are based on low-certainty evidence. There was however no evidence of beneficial effect for the number of participants who improved with the antipsychotics (RR 0.51, 95% CI 0.16 to 1.67; 2 studies, 43 participants) compared to placebo, based on very low-certainty evidence. For the outcome of treatment withdrawal, we found evidence of a harm for the individual SSRI agents compared with placebo (RR 1.41, 95% CI 1.07 to 1.87; 14 studies, 2399 participants). Withdrawals were also higher for the separate SSRI paroxetine group compared to the placebo group (RR 1.55, 95% CI 1.05 to 2.29; 5 studies, 1101 participants). Nonetheless, the absolute proportion of individuals dropping out from treatment due to adverse events in the SSRI groups was low (9%), based on moderate-certainty evidence. For the rest of the medications compared to placebo, we did not find evidence of harm for individuals dropping out from treatment due to adverse events.

AUTHORS' CONCLUSIONS

The findings of this review support the conclusion that SSRIs improve PTSD symptoms; they are first-line agents for the pharmacotherapy of PTSD, based on moderate-certainty evidence. The NaSSA mirtazapine and the TCA amitriptyline may also improve PTSD symptoms, but this is based on low-certainty evidence. In addition, we found no evidence of benefit for the number of participants who improved following treatment with the antipsychotic group compared to placebo, based on very low-certainty evidence. There remain important gaps in the evidence base, and a continued need for more effective agents in the management of PTSD.

Effectiveness, Acceptability and Safety of Pharmaceutical Management for Combat-Related PTSD in Adults Based on Systematic Review of Twenty-Two Randomized Controlled Trials

Objective: This study assessed the efficacy, acceptability, and safety of pharmaceutical management for combat-related post-traumatic stress disorder (PTSD) to provide a clinical decision-making basis for clinicians.

Method: A comprehensive search was conducted using Ovid MEDLINE, Ovid EMBASE, Cochrane Library, Scopus, ScienceDirect, and Web of Science for randomized controlled trails (RCTs), which reported pharmaceutical management and placobo for adults with combat-related PTSD, that were published until April 21, 2021. The effectiveness, acceptability, and adverse events (AEs), were designed as interested outcomes. The change in total symptoms of combat-related PTSD according to the clinician rating scale was defined as primary outcome, and the others were defined as secondary outcomes.

Results: Twenty-two RCTs with 1,221 patients were involved. Compared with placebo, overall active comparators had statistical differences for all outcomes, including the change in total symptoms of combat-related PTSD [SMD = −0.36, 95%CI (−0.62,−0.09)], depression [SMD = −0.28, 95%CI (−0.45,−0.10)], anxiety [SMD = −0.44, 95%CI (−0.64,−0.23)], re-experience [SMD = −0.33, 95%CI (−0.52,−0.13)], avoidance [SMD = −0.24, 95%CI (−0.43,−0.05)], and hyper-arousal [SMD = −0.26, 95%CI (−0.48,−0.03)]. Compared with the placebo, in terms of acceptability, overall active comparators did not significantly decrease all-cause discontinuance rates [RR = 0.97, 95%CI (0.78,1.20)], and the significance decreased due to AEs [RR = 2.42, 95%CI (1.41,4.13)]. Nevertheless, overall there was no statistically significant difference for overall AEs, including somnolence, sedation, dizziness, paresthesia, anxiety, blurred vision, generalized anxiety disorder, and sleep disturbance. All funnel plots were symmetrical and no publication bias was found.

Conclusion: Active drugs, especially amitriptyline, imipramine, and quetiapine, had a positive effect on the improvement of combat-related PTSD symptoms. Despite there being no significant increase in the AEs of the active drugs, the fact that the discontinuation rates of these drugs, including risperidone, imipramine, and topiramate, were increased deserves attention. Furthermore, as active drugs were effective across ethnic groups and battlefields, active drug regimens were revealed to be more appropriate for treating people with symptoms of extreme severe PTSD (≥80) or PTSD that is at least 8 weeks old. In addition, current evidence was from adults under 60 years of age and male combat-related PTSD. Whether this evidence can be extended to other populations of combat-related PTSD needs to be confirmed by subsequent high-quality, large-sample studies.

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

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

Key Clinical Interest Outcomes of Pharmaceutical Administration for Veterans With Post-Traumatic Stress Disorder Based on Pooled Evidences of 36 Randomised Controlled Trials With 2,331 Adults

Background: The effects of drug treatment on veterans, who have a high risk of post-traumatic stress disorder (PTSD), are not clear, and the guidelines are different from the recommendations of the recent meta-analysis. Our goal was to find the efficacy and frequencies of complications of drugs that can treat PTSD in veterans. Method: We searched Ovid MEDLINE, Ovid Embase, The Cochrane Library and Web of Science until January 1, 2020. The outcomes were designed as the change of PTSD total scale, subsymptom score, response rate, frequencies of complications outcomes, and acceptability. Results: We included a total of 36 randomised controlled trials with a total of 2,331 adults. In terms of overall effect, drug treatment is more effective than placebo in change in total PTSD symptoms scale (SMD = -0.24, 95% CI [-0.42, -0.06]) and response (RR = 1.66, 95% CI [1.01, 2.72]). However, in terms of frequencies of complications, drugs generally had a higher withdrawal rate (RR = 1.02, 95% CI [0.86, 1.20]) and a higher frequencies of complications (RR = 1.72, 95% CI [1.20, 2.47]) than placebo. Risperidone showed a good curative effect in change in total PTSD symptoms scale (SMD = -0.22, 95% CI [-0.43, 0.00]) and acceptability (RR = 1.31, 95% CI [0.82, 2.59]). The drugs acting on 5-HT receptors, our results showed that symptoms of hyper-arousal (SMD = -0.54, 95% CI [-0.86, -0.21]), symptoms of re-experiencing (SMD = -0.62, 95% CI [-0.86, -0.39]) and symptoms of avoidance (SMD = -0.53, 95% CI [- 0.77,-0.3]), The drugs acting on dopamine receptors, our results showed that symptoms of re-experiencing (SMD = -0.35, 95% CI [-0.55, -0.16]) and the drugs acting on α2 receptor has a significant effect on reducing total PTSD symptoms scale (SMD = -0.34, 95% CI [-0.62, -0.06]). Conclusion: Drug therapy can effectively treat PTSD, but its frequencies of complications should be considered. Different from the guidelines for adult PTSD, this study supports atypical antipsychotics, selective serotonin reuptake inhibitors and receptors that act on 5-HT and dopamine for the treatment of PTSD in veterans. Based on evidence among these drugs, the risperidone is the most effective for veterans, otherwise, sertraline is used as an alternative.

Comparative Efficacy and Acceptability of Pharmaceutical Management for Adults With Post-Traumatic Stress Disorder: A Systematic Review and Meta-Analysis

The current clinical guidelines on post-traumatic stress disorder (PTSD) recommend selective serotonin reuptake inhibitors (SSRIs) and serotonin and norepinephrine reuptake inhibitors (SNRIs) of drugs. However, there is uncertainty about the efficacy of other drugs and selecting which treatments work best for which patients. This meta-analysis evaluated efficacy and acceptability of pharmaceutical management for adults with PTSD. Randomized-controlled trials, which reported active comparators and placebo-controlled trials of pharmaceutical management for adults with PTSD, from the Ovid Medline, EMBase, CENTRAL, PsycINFO, Ovid Health and Psychosocial Instruments, and ISIWeb of Science, were searched until June 21, 2019. In terms of efficacy, all active drugs demonstrated superior effect than placebo (SMD = -0.33; 95% CI, -0.43 to -0.23). The medications were superior to placebo in reducing the symptom of re-experiencing, avoidance, hyperarousal, depression, and anxiety. For acceptability, medicine interventions for PTSD showed no increase in all-cause discontinuation compared with placebo. Nevertheless, in terms of safety, medicine interventions indicated a higher risk of adverse effect compared with placebo (RR = 1.47, 95% CI: 1.24 to 1.75). Compared with placebo, the SSRIs and atypical antipsychotics drugs had significant efficacy whether in patients with severe or extremely severe PTSD status. However, only atypical antipsychotics (SMD = -0.29, 95% CI: -0.48 to -0.10) showed superior efficacy than placebo in veterans. Medication management could be effective in intervention of PTSD, which demonstrated a sufficient improvement in the core symptoms. This meta-analysis supports the status of SSRIs and SNRIs as recommended pharmacotherapy. However, patients with different clinical characteristics of PTSD should consider individualized drug management.

Curculigoside facilitates fear extinction and prevents depression-like behaviors in a mouse learned helplessness model through increasing hippocampal BDNF

Curculigoside (CUR) is the main active component of traditional Chinese medicine Curculigoorchioides Gaertn (Xianmao in Chinese), which exhibits a variety of pharmacological activities. In this study we investigated the effects of CUR on fear extinction and related depression-like behaviors in mice. In fear conditioning task, we found that administration of CUR (1.6, 8, 40 mg·kg-1·d-1, ip, for 7 days) did not affect memory consolidation, but CUR at higher doses (8, 40 mg·kg-1·d-1) significantly facilitated fear extinction, especially on D3 and D4. Moreover, CUR administration significantly ameliorated the fear conditioning-induced depression-like behaviors, likely through promoting fear extinction. We showed that CUR increased the expression of brain-derived neurotrophic factor (BDNF) and phosphorylation of tropomyosin receptor kinase B (TrkB) in the hippocampus, and activated protein kinase B (Akt)-mammalian target of the rapamycin (mTOR) signaling pathway. Administration of the selective TrkB agonist 7,8-dihydroxyflavone (7,8-DHF, 5 mg·kg-1·d-1, ip) also facilitated fear extinction, ameliorated depression-like behaviors. We established a mouse learned helplessness (LH) model to evaluate the antidepressant activity of CUR. The spatial memory was assessed in Morris water maze. We showed that LH-induced depression-like behaviors, including prolonged immobility times in forced swim and tail suspension tests as well as spatial memory impairments; LH also downregulated BDNF expression and the Akt-mTOR signaling pathway in the hippocampus. Administration of CUR (1.6, 8, 40 mg·kg-1·d-1, ip, for 14 days) or 7,8-DHF (5 mg·kg-1·d-1, ip, for 3 days) prevented LH-induced depression-like behaviors and promoted BDNF expression and the Akt-mTOR signaling pathway. In conclusion, CUR can accelerate the fear memory extinction and ameliorate depression-like behaviors in mice via promoting BDNF expression and activating the Akt-mTOR signaling pathway in the hippocampus.

The hypothalamic-pituitary-adrenal axis in PTSD: Pathophysiology and treatment interventions

Questions of how altered functioning of the hypothalamic pituitary adrenal (HPA) axis contribute to the development and maintenance of posttraumatic stress disorder (PTSD) have been the focus of extensive animal and human research. As a rule, results have been inconsistent across studies, likely due to a variety of confounding variables that have received inadequate attention. Important confounding factors include the effects of early life stress, biological sex, and the glucocorticoid used for interventions. In this manuscript we review: 1) the literature on identified abnormalities of HPA axis function in PTSD, both in terms of basal functioning and as part of challenge paradigms; 2) the role of HPA axis function pre- and immediately post-trauma as a risk factor for PTSD development; 3) the impact of HPA axis genes' allelic variants and epigenetic modifications on PTSD risk; 4) the contributions of HPA axis components to fear learning and extinction; and 5) therapeutic manipulations of the HPA axis to both prevent and treat PTSD, including the role of glucocorticoids as part of medication enhanced psychotherapy.

Theranostic pharmacology in PTSD: Neurobiology and timing

Recent reviews and treatment guidelines regard trauma-focused cognitive-behavior therapies as the treatments of choice for chronic post-traumatic stress disorder (PTSD). However, many patients do not engage in this treatment when it is available, drop out before completion, or do not respond. Medications remain widely used, alone and in conjunction with psychotherapy, although the limitations of traditional monoamine-based pharmacotherapy are increasingly recognized. This article will review recent developments in psychopharmacology for PTSD, with a focus on current clinical data that apply putative neurobiologic mechanisms to medication use-i.e., a theranostic approach. A theranostic approach however, also requires consideration of timing, pre, peri or post trauma in conjunction with underlying dynamic processes affecting synaptic plasticity, the HPA axis, hippocampal activation, PFC-amygdala circuitry and fear memory.

Neuroendocrinological treatment targets for posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is prevalent, disabling, and frequently becomes chronic. Despite this, only two selective serotonergic reuptake inhibitors have been approved to date for its treatment by the United States Food and Drug Administration, and treatment results are often disappointing, with a remission rate of <30%. Certain neuroendocrinological systems are currently gaining attention with respect to their use for PTSD prevention and treatment as standalone options or medication-enhanced psychotherapy due to their involvement in physiological stress reactions, memory consolidation and extinction, cognitive appraisal to stress, and attachment and resilient coping strategies, which are important in the pathogenesis of PTSD. The hypothalamic-pituitary-adrenal axis system takes the most important role in stress reactions. Hydrocortisone has been studied for the prevention of PTSD, and some meta-analyses have suggested its possible efficacy; furthermore, it has been considered both as monotherapy and as an augmentation to psychotherapy in PTSD patients, with some positive results. Glucocorticoid receptor antagonists and corticotropin-releasing factor type 1 antagonists have also been considered for clinical use in PTSD treatment. Additionally, other neuroendocrinological systems have been studied in PTSD including the use of oxytocin for PTSD prevention and augmentation to psychotherapy, allopregnanolone, and neuropeptide Y (NPY) for PTSD treatment. For now, however, these studies offer only limited evidence of efficacy, thus it is prudent to study this issue more vigorously.

When translational neuroscience fails in the clinic: Dexamethasone prior to virtual reality exposure therapy increases drop-out rates

Posttraumatic stress disorder (PTSD) is characterized by exaggerated expression of fear responses to danger and safety cues. Translational research suggests that dexamethasone facilitates fear extinction in animal and human fear conditioning models. For this randomized, placebo-controlled trial (N = 27), we aimed to translate these findings to the clinic by using virtual reality exposure (VRE) therapy for OEF/OIF/OND veterans with PTSD to determine whether dexamethasone will increase the efficacy of exposure therapy for VRE relative to placebo. VRE sessions involved imaginal exposure to the most traumatic war memories while viewing a computer-generated view of virtual Iraq or Afghanistan with multisensory stimulus options used to match patient's description of the trauma. VRE was effective in reducing PTSD symptoms but there was no interaction with dexamethasone. Drop-out rate was significantly higher in the dexamethasone group, with 10 of 13 (76.9%) participants in this group discontinuing, compared to only 4 of 14 (28.5%) in the placebo group, χ² = 6.31, p = 0.02. Results indicate that the dexamethasone group may have experienced an increase in PTSD symptoms, particularly re-experiencing, at session 2 following first drug administration. Contrary to study hypotheses, dexamethasone did not enhance exposure therapy outcomes and was associated with increased drop-out. This demonstrates potential pitfalls in translating neuroscience models to the clinic; future research carefully examining glucocorticoid mechanisms involved in therapy augmentation is warranted.

Characterizing changes in glucocorticoid receptor internalization in the fear circuit in an animal model of post traumatic stress disorder

Glucocorticoid receptors (GRs) shuttle from the cytoplasm (cy) to the nucleus (nu) when bound with glucocorticoids (i.e. GR internalization) and alter transcriptional activity. GR activation within the fear circuit has been implicated in fear memory and post traumatic stress disorder (PTSD). However, no study to date has characterized GR internalization within the fear circuit during fear memory formation or examined how traumatic stress impacts this process. To address this, we assayed cy and nu GR levels at baseline and after auditory fear conditioning (FC) in the single prolonged stress (SPS) model of PTSD. Cy and nu GRs within the medial prefrontal cortex (mPFC), dorsal hippocampus (dHipp), ventral hippocampus (vHipp), and amygdala (AMY) were assayed using western blot. The distribution of GR in the cy and nu (at baseline and after FC) was varied across individual nodes of the fear circuit. At baseline, SPS enhanced cyGRs in the dHipp, but decreased cyGRs in the AMY. FC only enhanced GR internalization in the AMY and this effect was attenuated by SPS exposure. SPS also decreased cyGRs in the dHipp after FC. The results of this study suggests that GR internalization is varied across the fear circuit, which in turn suggests GR activation is selectively regulated within individual nodes of the fear circuit. The findings also suggest that changes in GR dynamics in the dHipp and AMY modulate the enhancing effect SPS has on fear memory persistence.