Enhancing exposure therapy for anxiety disorders with glucocorticoids: from basic mechanisms of emotional learning to clinical applications

CBT reduces CBF: cognitive-behavioral therapy reduces cerebral blood flow in fear-relevant brain regions in spider phobia

BACKGROUND

Imaging studies have provided evidence that cognitive-behavioral therapy (CBT) is able to change brain activation in phobic patients in response to threatening stimuli. The changes occurred in both emotion-generating and modulatory regions. In this study, we use a data-driven approach to explore resting state cerebral blood flow (CBF) measured by arterial spin labeling (ASL), before and after CBT.

METHODS

Eight female patients with spider phobia were scanned before and 1 month after an exposure-based group therapy for spider phobia. Each MRI session consisted of an ASL resting state measurement acquired before and after a symptom provocation task involving the showing of spider pictures in the scanner. The first ASL acquisition measured anticipatory anxiety and the second measured postprocessing of phobia-relevant stimuli.

RESULTS

Cognitive-behavioral therapy significantly reduced spider phobic symptoms in all patients. Symptom reduction during anticipatory anxiety was accompanied by reduced bilateral CBF in the parahippocampal gyrus, ventral anterior thalamus, Brodmann area 8, and the anterior cingulate cortex. During postprocessing of phobia-relevant stimuli, patients showed reduced CBF in the bilateral insula, components of the motor cortex, and areas associated with language functions.

CONCLUSIONS

Longitudinal CBF dynamics following CBT were in concordance with results from several studies using BOLD fMRI to investigate the effects of psychotherapy on brain activity. CBF can be quantified by ASL, with the principal advantage of sensitivity to slow variations in neural activity and task independence. Therefore, ASL may be a suitable method for monitoring and evaluating the efficacy of psychotherapy or pharmacotherapy approaches.

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.

Stress: perspectives on its impact on cognition and pharmacological treatment

Stress in life is unavoidable, affecting everyone on a daily basis. Psychological stress in mammals triggers a rapidly organized response for survival, but it may also cause a variety of behavioral disorders and damage cognitive function. Stress is associated with biases in cognitive processing; some of the most enduring memories are formed by traumatic events. Our understanding of how cognition is shaped by stress is still relatively primitive; however, evidence is rapidly accumulating that the 'mature' brain has a great capacity for plasticity and that there are numerous ways through which pharmacological therapeutics could rescue cognitive function and regain cognitive balance. In this review, we discuss recent advances in our understanding of the interplay between stress and cognitive processes and potential therapeutic approaches to stress-related behavioral and cognitive disorders.

Biological and symptom changes in posttraumatic stress disorder treatment: a randomized clinical trial

BACKGROUND

Understanding cognitive and biological mechanisms of PTSD treatment can help refine treatments and increase rates of response.

METHODS

Thirty-six veterans with PTSD were randomly assigned to receive Prolonged exposure therapy (PE) or Present-Centered therapy (PCT). We examined symptoms, trauma-related cognitions, and two indices of HPA axis function (cortisol awakening response and cortisol response to a script-driven imagery task).

RESULTS

Thirty veterans started treatment and 26 completed. PE resulted in significantly more symptom reduction than PCT (P = .008). High treatment responders collapsed across treatments showed nominally higher cortisol levels measured at pretreatment 30 min after trauma script exposure compared to low responders (P = .08). At midtreatment, high treatment responders showed higher cortisol levels throughout the imagery task (Ps = .03-.04). There were no differences between high and low treatment responders at posttreatment. Thoughts of incompetence (F (1.6, 35.8) = 16.8, P = .000) and a dangerous world (F (1.3, 29.9) = 8.2, P = .004) significantly improved over time in high treatment responders but showed no change in low responders. Script-associated cortisol response prior to treatment and reductions in thoughts of incompetence accounted for 83% of the variance in reductions in PTSD severity with PE.

CONCLUSIONS

Both increased cortisol response to personal trauma script prior to PTSD therapy and reductions in cognitive symptoms of PTSD were significantly and uniquely related to reductions in the core symptoms of PTSD in PE. However, contrary to our hypotheses, cortisol measures were not related to cognitive changes.

Fear reactivation prior to exposure therapy: does it facilitate the effects of VR exposure in a randomized clinical sample?

BACKGROUND AND OBJECTIVES

The current study is the first to examine whether reactivation of fear memory prior to exposure therapy reduces relapse in a randomized clinical sample.

METHODS

In a standardized treatment protocol combining virtual reality and in-vivo exposure, patients underwent a fear reactivation procedure using a virtual spider 10 min prior to a virtual reality (VR) exposure (reactivation group: RG, n = 15). A control group (CG, n = 17) was exposed to a virtual plant 10 min prior to the VR exposure. Outcome measures were a VR spontaneous recovery test (SRT) and in-vivo a behavioral avoidance test assessed 24 h after VR exposure. One week later an in-vivo exposure session followed. Additionally, a follow-up using psychometric assessment was conducted six months after the first session.

RESULTS

Both groups benefitted significantly and equally from the combined treatment, and importantly, the SRT revealed no return of fear in both groups. Furthermore, follow-up tests showed long-term treatment effects with no group differences.

LIMITATIONS

Due to different study components (VR treatment and in-vivo), we were not able to determine which treatment module was mainly responsible for the long-term treatment effect. Furthermore, no direct measure of memory destabilization was possible in this study.

CONCLUSIONS

Our treatment package was highly effective in reducing phobic fear up to 6 months following treatment. Explicit fear reactivation prior to exposure was not beneficial in VR exposure treatment, possibly due to a failure to induce a memory destabilization or due to an implicit fear reactivation prior to treatment in both groups.

High cortisol awakening response and cortisol levels moderate exposure-based psychotherapy success

BACKGROUND

Research suggests that elevated stress hormones during exposure can facilitate fear extinction in laboratory settings. However, prospective studies on the clinical benefits of endogenous cortisol on clinical improvements in naturalistic exposures are lacking.

METHODS

Twenty-six patients with panic disorder and agoraphobia completed three weekly in-vivo exposure sessions and a fourth session 2 months following therapy completion, resulting in a total of 94 in-vivo exposure sessions. Salivary cortisol was collected at multiple times during the first exposure day (cortisol morning response, prior, -during, -after exposure) and at subsequent exposure sessions (prior, -during, -after exposure). Cortisol collection on a non-exposure comparison day followed the same time schedule as session 1.

RESULTS

Exposure day anxiety and cortisol levels were significantly higher than control day levels. Higher absolute cortisol levels during exposures moderated clinical improvement (avoidance behavior, threat appraisal, perceived control). Therapeutic gains were not just related to exposure day cortisol levels, but were also linked to non-exposure day levels. Greater morning rises in cortisol on exposure day predicted greater treatment gains, but greater rises on the control day were associated with poorer outcomes.

CONCLUSIONS

The study provides first evidence for a moderating effect of cortisol awakening response and absolute cortisol levels on fear extinction processes during naturalistic, prospective exposure-therapy. Additionally, we replicated and extended prior findings on the therapeutic benefits of high exposure cortisol levels. Together, the findings suggest that cortisol may act as a general moderator of facilitated learning during exposure therapy.

Suicide history and mortality: a follow-up of a national cohort in the United States

Little is known about the cause-specific deaths among young suicide attempters from the general population, and the time window for intervention to reduce the elevated rate of death was unclear. We analyzed a nationally representative sample of young adults (17-39 years old) who participated in the third National Health and Nutrition Examination Survey (NHANES III, 1988-1994) and were followed up with vital status through December 31, 2006. The history of attempted suicide was associated with an increased rate for all-cause death (HR = 1.52 [95% CI = 0.92-2.52]) with borderline statistical significance. Previous suicide attempters experienced a 3-fold (HR = 2.68[=1.01-7.09]) increased rate for cardiovascular diseases (CVD), and a 7-fold (HR = 7.10 [95% CI = 1.37-36.9]) increased rate of death due to completed suicide compared with non-attempters. The survival curves of the attempters declined rapidly for the first 3 years of follow-up, and the distance between curves remained consistent starting from the third year to the end of the follow-up. Prevention services should be tailored not only for suicide, but also for cardiovascular diseases among populations with suicidal tendency, and the service should be intensified within first 3 years after suicidal behaviors occur.

Pharmacology of cognitive enhancers for exposure-based therapy of fear, anxiety and trauma-related disorders

Pathological fear and anxiety are highly debilitating and, despite considerable advances in psychotherapy and pharmacotherapy they remain insufficiently treated in many patients with PTSD, phobias, panic and other anxiety disorders. Increasing preclinical and clinical evidence indicates that pharmacological treatments including cognitive enhancers, when given as adjuncts to psychotherapeutic approaches [cognitive behavioral therapy including extinction-based exposure therapy] enhance treatment efficacy, while using anxiolytics such as benzodiazepines as adjuncts can undermine long-term treatment success. The purpose of this review is to outline the literature showing how pharmacological interventions targeting neurotransmitter systems including serotonin, dopamine, noradrenaline, histamine, glutamate, GABA, cannabinoids, neuropeptides (oxytocin, neuropeptides Y and S, opioids) and other targets (neurotrophins BDNF and FGF2, glucocorticoids, L-type-calcium channels, epigenetic modifications) as well as their downstream signaling pathways, can augment fear extinction and strengthen extinction memory persistently in preclinical models. Particularly promising approaches are discussed in regard to their effects on specific aspects of fear extinction namely, acquisition, consolidation and retrieval, including long-term protection from return of fear (relapse) phenomena like spontaneous recovery, reinstatement and renewal of fear. We also highlight the promising translational value of the preclinial research and the clinical potential of targeting certain neurochemical systems with, for example d-cycloserine, yohimbine, cortisol, and L-DOPA. The current body of research reveals important new insights into the neurobiology and neurochemistry of fear extinction and holds significant promise for pharmacologically-augmented psychotherapy as an improved approach to treat trauma and anxiety-related disorders in a more efficient and persistent way promoting enhanced symptom remission and recovery.

Who is stressed? A pilot study of salivary cortisol and alpha-amylase concentrations in agoraphobic patients and their novice therapists undergoing in vivo exposure

In cognitive behavioural therapy of phobic anxiety, in vivo exposure is considered as an effective treatment strategy. Apparently, it involves the experience of stress and anxiety in patients. Given the therapist's role during exposure sessions, it is conceivable that the performance is also accompanied with the experience of stress in therapists, especially when unversed in conducting psychotherapy. Studies confirmed that cognitive behavioural therapists tend to avoid therapist-guided in vivo exposure. The objective of this study was the simultaneous investigation of therapist's and patient's stress response during in vivo exposure. Therefore, 23 agoraphobic patients and their 23 treating therapists in training provided five saliva samples during an in vivo exposure and five samples during an ordinary therapy session. Before and during exposure session, subjective evaluations of stress and anxiety were assessed. Results suggested that therapists reported similar levels of perceived stress as patients before exposure. Both groups displayed significantly elevated salivary cortisol (sC) levels during exposure compared to the control session and a trend for alterations in salivary alpha-amylase (sAA) activity was found. Therapists reached peak concentrations of sC before start of the intervention followed by a decline during exposure, while patients displayed peak levels of cortisol secretion after 60 min of exposure. In vivo exposure seems to be a demanding intervention not only for the patient, but also for therapists in training. However, it was also demonstrated that physiological and subjective stress rather decrease during the intervention and that both groups rated exposure to be substantially successful. Based on the presented results, another potential factor contributing to the under-usage of exposure treatment is conceivable and needs to be addressed in future research.

Remembering the object you fear: brain potentials during recognition of spiders in spider-fearful individuals

In the present study we investigated long-term memory for unpleasant, neutral and spider pictures in 15 spider-fearful and 15 non-fearful control individuals using behavioral and electrophysiological measures. During the initial (incidental) encoding, pictures were passively viewed in three separate blocks and were subsequently rated for valence and arousal. A recognition memory task was performed one week later in which old and new unpleasant, neutral and spider pictures were presented. Replicating previous results, we found enhanced memory performance and higher confidence ratings for unpleasant when compared to neutral materials in both animal fearful individuals and controls. When compared to controls high animal fearful individuals also showed a tendency towards better memory accuracy and significantly higher confidence during recognition of spider pictures, suggesting that memory of objects prompting specific fear is also facilitated in fearful individuals. In line, spider-fearful but not control participants responded with larger ERP positivity for correctly recognized old when compared to correctly rejected new spider pictures, thus showing the same effects in the neural signature of emotional memory for feared objects that were already discovered for other emotional materials. The increased fear memory for phobic materials observed in the present study in spider-fearful individuals might result in an enhanced fear response and reinforce negative beliefs aggravating anxiety symptomatology and hindering recovery.

Emotions and cognitions: a critique of the dichotomous view of mental function

Many approaches to the psyche, models of therapy, and neuroscience tend to view emotional and cognitive brain functions as separate entities. Such a focus on one of these two aspects of mental function, at times comes at the expense of ignoring the other. In this paper emotions and cognitions, along with perceptions and other elements of the internal and external contexts, are viewed as relevant vectors in a matrix of information. Through the processes of pattern completion and noise reduction, information in each of these vectors may evoke memories in the same or other vectors that are used in the formation of a subjective understanding of each experience. The important roles of the external (physical, temporal, relevant events, etc.) and internal (emotional, affective, hormonal, medications, etc.) contexts in the formation of such subjective experiences will be discussed. The use of this view in broader and more comprehensive psychotherapeutic approaches and combined pharmacological and psychological treatment is explored.

Melatonin facilitates extinction, but not acquisition or expression, of conditional cued fear in rats

Background

Previous studies have shown that melatonin is involved in the processes that contribute to learning and memory. At present study, we tested the effects of exogenous melatonin (2.5 mg/kg) on the acquisition, expression and extinction of cued fear in rats.

Results

Results showed that a single afternoon administration 30 min before conditioning has no effect on the acquisition of cued fear. Compared to rats injected with vehicle, rats injected with melatonin 30 min before extinction training presented a significant lower freezing during both extinction training and extinction test phases, however, freezing response did not differ for the initial four trials during extinction training. Melatonin injected immediately after extinction training was ineffective on extinction learning.

Conclusions

These results suggest that melatonin, at the dose applied in this study, facilitates the extinction of conditional cued fear without affecting its acquisition or expression, and melatonin facilitates cued fear extinction only when it is present during extinction training. These findings extend previous research on the melatonin effects on learning and memory and suggest that melatonin may serve as an agent for the treatment of anxiety disorders such as posttraumatic stress disorder (PTSD).

Endogenous cortisol levels influence exposure therapy in spider phobia

Previous research in patients with phobia showed that the administration of glucocorticoids reduces fear in phobic situations and enhances exposure therapy. Glucocorticoids underlie a daily cycle with a peak in the morning and low levels during the evening and night. The aim of the present study was to investigate whether exposure is more effective when conducted in the morning when endogenous cortisol levels are high. Sixty patients meeting DSM IV criteria for specific phobia (animal type) were randomly assigned to one-session exposure treatment either at 08.00 a.m. (high cortisol group) or at 06.00 p.m. (low cortisol group). Participants returned for a posttreatment assessment one week after therapy and a follow-up assessment three months after therapy. Both groups showed good outcome, but patients treated in the morning exhibited significantly less fear of spiders in the behavioral approach test (BAT) and a trend for lower scores on the Fear of Spiders Questionnaire (FSQ) than patients treated in the evening. This effect was present at posttreatment and follow-up. Our findings indicate that exposure therapy is more effective in the morning than in the evening. We suggest that this may be due to higher endogenous cortisol levels in the morning group that enhance extinction memory.

Corticosteroid-endocannabinoid loop supports decrease of fear-conditioned response in rats

The endocannabinoid (eCB) and glucocorticoid systems contribute to the modulation of emotional states. Noteworthy, glucocorticoid hormones are released by adrenal glands during stressful events and endocannabinoids are released in the brain during fear-conditioned responses. Since it was already suggested that glucocorticoids may trigger the release of endocannabinoids in the brain, our objective was to investigate whether the interaction between these neuromodulatory systems contributes to the decrease of conditioned freezing behavior over successive 9-min exposures to the conditioning context. Present results suggest a bidirectional interdependence between glucocorticoid and endocannabinoid systems. CB1 receptors blockade prevents glucocorticoid-induced facilitation of conditioned freezing decrease and inhibition of glucocorticoid synthesis renders boosting of endocannabinoid signaling innocuous, while preserving the efficacy of direct CB1 receptors activation by an exogenous cannabinoid agonist. This suggests that CB1 receptors are somehow "downstream" to glucocorticoid release, which in its turn, is reduced by CB1 activation, contributing to the persistent reduction of conditioned freezing responses.

The role of FKBP5 genotype in moderating long-term effectiveness of exposure-based psychotherapy for posttraumatic stress disorder

Exposure-based therapies are considered the state-of-the-art treatment for Posttraumatic Stress Disorder (PTSD). Yet, a substantial number of PTSD patients do not recover after therapy. In the light of the well-known gene × environment interactions on the risk for PTSD, research on individual genetic factors that influence treatment success is warranted. The gene encoding FK506-binding protein 51 (FKBP5), a co-chaperone of the glucocorticoid receptor (GR), has been associated with stress reactivity and PTSD risk. As FKBP5 single-nucleotide polymorphism rs1360780 has a putative functional role in the regulation of FKBP5 expression and GR sensitivity, we hypothesized that this polymorphism influences PTSD treatment success. We investigated the effects of FKBP5 rs1360780 genotype on Narrative Exposure Therapy (NET) outcome, an exposure-based short-term therapy, in a sample of 43 survivors of the rebel war in Northern Uganda. PTSD symptom severity was assessed before and 4 and 10 months after treatment completion. At the 4-month follow-up, there were no genotype-dependent differences in therapy outcome. However, the FKBP5 genotype significantly moderated the long-term effectiveness of exposure-based psychotherapy. At the 10-month follow-up, carriers of the rs1360780 risk (T) allele were at increased risk of symptom relapse, whereas non-carriers showed continuous symptom reduction. This effect was reflected in a weaker treatment effect size (Cohen's D=1.23) in risk allele carriers compared with non-carriers (Cohen's D=3.72). Genetic factors involved in stress response regulation seem to not only influence PTSD risk but also responsiveness to psychotherapy and could hence represent valuable targets for accompanying medication.

Maternal separation enhances conditioned fear and decreases the mRNA levels of the neurotensin receptor 1 gene with hypermethylation of this gene in the rat amygdala

Stress during postnatal development is associated with an increased risk for depression, anxiety disorders, and substance abuse later in life, almost as if mental illness is able to be programed by early life stressors. Recent studies suggest that such “programmed” effects can be caused by epigenetic regulation. With respect to conditioned fear, previous studies have indicated that early life stress influences its development in adulthood, whereas no potential role of epigenetic regulation has been reported. Neurotensin (NTS) is an endogenous neuropeptide that has receptors densely located in the amygdala and hippocampus. Recently, NTS systems have constituted an emerging target for the treatment of anxiety. The aim of the present work is to clarify whether the NTS system is involved in the disturbance of conditioned fear in rats stressed by maternal separation (MS). The results showed that MS enhanced freezing behaviors in fear-conditioned stress and reduced the gene expression of NTS receptor (NTSR) 1 but not of NTS or NTSR2 in the amygdalas of adult rats. The microinjection of a NTSR1 antagonist into the amygdala increased the percentage of freezing in conditioned fear, whereas the microinjection of NTSR1 agonist decreased freezing. These results suggest that NTSR1 in the amygdala may play a role in the effects of MS on conditioned fear stress in adult rats. Moreover, MS increased DNA methylation in the promoter region of NTSR1 in the amygdala. Taken together, MS may leave epigenetic marks in the NTSR1 gene in the amygdala, which may enhance conditioned fear in adulthood. The MS-induced alternations of DNA methylation in the promoter region of NTSR1 in the amygdala may be associated with vulnerability to the development of anxiety disorders and depression in adulthood.

Glucocorticoids enhance in vivo exposure-based therapy of spider phobia

BACKGROUND

Preclinical and clinical studies indicate that the administration of glucocorticoids may promote fear extinction processes. In particular, it has been shown that glucocorticoids enhance virtual reality based exposure therapy of fear of heights. Here, we investigate whether glucocorticoids enhance the outcome of in vivo exposure-based group therapy of spider phobia.

METHODS

In a double blind, block-randomized, placebo-controlled, between-subject study design, 22 patients with specific phobia of spiders were treated with two sessions of in vivo exposure-based group therapy. Cortisol (20 mg) or placebo was orally administered 1 hr before each therapy session. Patients returned for a follow-up assessment one month after therapy.

RESULTS

Exposure-based group therapy led to a significant decrease in phobic symptoms as assessed with the Fear of Spiders Questionnaire (FSQ) from pretreatment to immediate posttreatment and to follow-up. The administration of cortisol to exposure therapy resulted in increased salivary cortisol concentrations and a significantly greater reduction in fear of spiders (FSQ) as compared to placebo at follow-up, but not immediately posttreatment. Furthermore, cortisol-treated patients reported significantly less anxiety during standardized exposure to living spiders at follow-up than placebo-treated subjects. Notably, groups did not differ in phobia-unrelated state-anxiety before and after the exposure sessions and at follow-up.

CONCLUSIONS

These findings indicate that adding cortisol to in vivo exposure-based group therapy of spider phobia enhances treatment outcome.

Exposure to stress attenuates fear retrieval in healthy men

The stress hormone cortisol reduces retrieval of emotional memories, which has been suggested to support the treatment of psychiatric disorders characterized by exaggerated fear-related memories. Indeed, studies in patients with anxiety disorders have indicated that the success of exposure therapy can be enhanced with accompanying cortisol administration. Fear renewal refers to the clinically relevant phenomenon that successfully extinguished fear can return after a context change. It remains to be investigated whether the effects of stress hormones on fear retrieval also generalize across different contexts. Healthy men were exposed to a fear renewal design with fear acquisition in context A and extinction in context B. Pictures of rooms served as contexts, coloured lights were introduced as conditioned stimuli (CS), and an electrical stimulation served as the unconditioned stimulus (UCS). On the next day, participants were randomly assigned to a stress (Socially Evaluated Cold Pressor Test) or a control condition (n=20 each). We tested for fear retrieval in contexts A and B during peak cortisol concentrations after stress induction. Overall, a context×stress interaction occurred, revealing that stress attenuated skin conductance responses in the extinction context B. Stress also reduced UCS expectancy in context B. Additionally, stress abolished the renewal effect (differentiation between CS in context A) at the electrodermal level. These results demonstrate a decreased return of fear after acute exposure to stress. Stress interferes with the retrieval of the original fear memory which in turn affects extinction responding. Thus, acute stress reduces rather than promotes the return of fear.

Prospects for the pharmacological prevention of post-traumatic stress in vulnerable individuals

Biological studies of posttraumatic stress disorder (PTSD) have found alterations of physiological stress pathways [sympathetic nervous system (SNS) and the hypothalamic-pituitary-adrenal (HPA) axis] soon after trauma in individuals who have subsequently developed PTSD, leading researchers to hypothesize that pharmacological manipulation of stress hormone levels may aid in preventing the development of post-traumatic distress. The present paper first reviews the current understanding of the neurobiology of PTSD development and then provides the rationale and evidence for early pharmacological strategies to prevent/reduce post-traumatic distress in at-risk trauma victims. Emphasis is placed on those interventions targeting the SNS and the HPA axis. Furthermore, in light of recent calls to move away from categorical diagnostic outcomes, we discuss how examining post-traumatic distress from a transdiagnostic viewpoint may inform novel chemoprophylactic approaches (intervening pharmacologically after trauma to prevent post-traumatic distress). Current evidence is suggestive for medications, such as propranolol, hydrocortisone, morphine, and oxytocin, impacting early stress hormone levels and subsequent risk for post-traumatic distress; however, future research is needed prior to adapting recommendations for widespread use of any chemoprophylactic treatments.

The Future of D-Cycloserine and Other Cognitive Modifiers in Obsessive-Compulsive and Related Disorders

Variants of exposure therapy are effective for treating obsessive-compulsive and related disorders (OCRDs). However, significant numbers of patients do not respond adequately to exposure therapy resulting in continued distress and functional impairment. Therefore, novel approaches to augmenting exposure therapy are needed to adequately treat non- and partial-responders. Emerging research suggests that interventions that augment learning and memory processes associated with exposure therapy (i.e., extinction training) may display promise in enhancing treatment response in OCRDs. As the most studied example, d-cycloserine (DCS) is a relatively safe cognitive enhancer that appears to accelerate treatment gains associated with exposure therapy. This article reviews research on the use of DCS and other putative cognitive modifiers as they relate to the treatment (or prospective treatment) of obsessive-compulsive disorder and other OCRDs.

Extinction of conditioned fear is better learned and recalled in the morning than in the evening

Sleep helps emotional memories consolidate and may promote generalization of fear extinction memory. We examined whether extinction learning and memory might differ in the morning and evening due, potentially, to circadian and/or sleep-homeostatic factors. Healthy men (N = 109) in 6 groups completed a 2-session protocol. In Session 1, fear conditioning was followed by extinction learning. Partial reinforcement with mild electric shock produced conditioned skin conductance responses (SCRs) to 2 differently colored lamps (CS+), but not a third color (CS-), within the computer image of a room (conditioning context). One CS+ (CS + E) but not the other (CS + U) was immediately extinguished by un-reinforced presentations in a different room (extinction context). Delay durations of 3 h (within AM or PM), 12 h (morning-to-evening or evening-to-morning) or 24 h (morning-to-morning or evening-to-evening) followed. In Session 2, extinction recall and contextual fear renewal were tested. We observed no significant effects of the delay interval on extinction memory but did observe an effect of time-of-day. Fear extinction was significantly better if learned in the morning (p = .002). Collapsing across CS + type, there was smaller morning differential SCR at both extinction recall (p = .003) and fear renewal (p = .005). Morning extinction recall showed better generalization from the CS + E to CS + U with the response to the CS + U significantly larger than to the CS + E only in the evening (p = .028). Thus, extinction is learned faster and its memory is better generalized in the morning. Cortisol and testosterone showed the expected greater salivary levels in the morning when higher testosterone/cortisol ratio also predicted better extinction learning. Circadian factors may promote morning extinction. Alternatively, evening homeostatic sleep pressure may impede extinction and favor recall of conditioned fear.

Stress and glucocorticoid receptor-dependent mechanisms in long-term memory: from adaptive responses to psychopathologies

A proper response against stressors is critical for survival. In mammals, the stress response is primarily mediated by secretion of glucocorticoids via the hypothalamic-pituitary-adrenocortical (HPA) axis and release of catecholamines through adrenergic neurotransmission. Activation of these pathways results in a quick physical response to the stress and, in adaptive conditions, mediates long-term changes in the brain that lead to the formation of long-term memories of the experience. These long-term memories are an essential adaptive mechanism that allows an animal to effectively face similar demands again. Indeed, a moderate stress level has a strong positive effect on memory and cognition, as a single arousing or moderately stressful event can be remembered for up to a lifetime. Conversely, exposure to extreme, traumatic, or chronic stress can have the opposite effect and cause memory loss, cognitive impairments, and stress-related psychopathologies such as anxiety disorders, depression and post-traumatic stress disorder (PTSD). While more effort has been devoted to the understanding of the negative effects of chronic stress, much less has been done thus far on the identification of the mechanisms engaged in the brain when stress promotes long-term memory formation. Understanding these mechanisms will provide critical information for use in ameliorating memory processes in both normal and pathological conditions. Here, we will review the role of glucocorticoids and glucocorticoid receptors (GRs) in memory formation and modulation. Furthermore, we will discuss recent findings on the molecular cascade of events underlying the effect of GR activation in adaptive levels of stress that leads to strong, long-lasting memories. Our recent data indicate that the positive effects of GR activation on memory consolidation critically engage the brain-derived neurotrophic factor (BDNF) pathway. We propose and will discuss the hypothesis that stress promotes the formation of strong long-term memories because the activation of hippocampal GRs after learning is coupled to the recruitment of the growth and pro-survival BDNF/cAMP response element-binding protein (CREB) pathway, which is well-know to be a general mechanism required for long-term memory formation. We will then speculate about how these results may explain the negative effects of traumatic or chronic stress on memory and cognitive functions.

Cannabinoids and traumatic stress modulation of contextual fear extinction and GR expression in the amygdala-hippocampal-prefrontal circuit

Considerable evidence suggests that cannabinoids modulate the behavioral and physiological response to stressful events. We have recently shown that activating the cannabinoid system using the CB1/CB2 receptor agonist WIN55,212-2 (WIN) in proximity to exposure to single-prolonged stress (SPS), a rat model of emotional trauma, prevented the stress-induced enhancement of acoustic startle response, the impairment in avoidance extinction and the enhanced negative feedback on the hypothalamic-pituitary-adrenal (HPA) axis (Ganon-Elazar and Akirav, 2012). Some of the effects were found to be mediated by CB1 receptors in the basolateral amygdala (BLA). Here we examined whether cannabinoid receptor activation in a putative brain circuit that includes the BLA, hippocampus and prefrontal cortex (PFC), could prevent the effects of traumatic stress on contextual fear extinction and alterations in glucocorticoid receptor (GR) protein levels. We found that: (i) SPS impaired contextual fear extinction tested one week after trauma exposure and that WIN prevented the stress-induced impairment of extinction when microinjected immediately after trauma exposure into the BLA or hippocampus (5 μg), but not when microinjected into the PFC, (ii) the ameliorating effects of WIN on contextual extinction were prevented by blocking GRs in the BLA and hippocampus, and (iii) SPS up regulated GRs in the BLA, PFC and hippocampus and systemic WIN administration (0.5 mg/kg) after trauma exposure normalized GR levels in the BLA and hippocampus, but not in the PFC. Cannabinoid receptor activation in the aftermath of trauma exposure may regulate the emotional response to the trauma and prevent stress-induced impairment of extinction and GR up regulation through the mediation of CB1 receptors in the BLA and hippocampus. Taken together, the findings suggest that the interaction between the cannabinoid and glucocorticoid systems is crucial in the modulation of emotional trauma.

Stress enhances the consolidation of extinction memory in a predictive learning task

Extinction is not always permanent, as indicated by several types of recovery effects, such as the renewal effect, which may occur after a context change and points towards the importance of contextual cues. Strengthening the retrieval of extinction memory is a crucial aim of extinction-based psychotherapeutic treatments of anxiety disorders to prevent relapse. Stress is known to modulate learning and memory, with mostly enhancing effects on memory consolidation. However, whether such a consolidation-enhancing effect of acute stress can also be found for extinction memory has not yet been examined in humans. In this study, we investigated the effect of stress after extinction learning on the retrieval of extinction memory in a predictive learning renewal paradigm. Participants took the part of being the doctor of a fictitious patient and learned to predict whether certain food stimuli were associated with "stomach trouble" in two different restaurants (contexts). On the first day, critical stimuli were associated with stomach trouble in context A (acquisition phase). On the second day, these associations were extinguished in context B. Directly after extinction, participants were either exposed to a stressor (socially evaluated cold pressor test; n = 22) or a control condition (n = 24). On the third day, we tested retrieval of critical associations in contexts A and B. Participants exposed to stress after extinction exhibited a reduced recovery of responding at test in context B, suggesting that stress may context-dependently enhance the consolidation of extinction memory. Furthermore, the increase in cortisol in response to the stressor was negatively correlated with the recovery of responding in context A. Our findings suggest that in parallel to the known effects of stress on the consolidation of episodic memory, stress also enhances the consolidation of extinction memory, which might be relevant for potential applications in extinction-based psychotherapy.

Cortisol modifies extinction learning of recently acquired fear in men

Exposure therapy builds on the mechanism of fear extinction leading to decreased fear responses. How the stress hormone cortisol affects brain regions involved in fear extinction in humans is unknown. For this reason, we tested 32 men randomly assigned to receive either 30 mg hydrocortisone or placebo 45 min before fear extinction. In fear acquisition, a picture of a geometrical figure was either partially paired (conditioned stimulus; CS+) or not paired (CS-) with an electrical stimulation (unconditioned stimulus; UCS). In fear extinction, each CS was presented again, but no UCS occurred. Cortisol increased conditioned skin conductance responses in early and late extinction. In early extinction, higher activation towards the CS- than to the CS+ was found in the amygdala, hippocampus and posterior parahippocampal gyrus. This pattern might be associated with the establishment of a new memory trace. In late extinction, the placebo compared with the cortisol group displayed enhanced CS+/CS- differentiation in the amygdala, medial frontal cortex and nucleus accumbens. A change from early deactivation to late activation of the extinction circuit as seen in the placebo group seems to be needed to enhance extinction and to reduce fear. Cortisol appears to interfere with this process thereby impairing extinction of recently acquired conditioned fear.

Influence of stress on fear memory processes in an aversive differential conditioning paradigm in humans

It is widely assumed that learning and memory processes play an important role in the pathogenesis, expression, maintenance and therapy of anxiety disorders, such as phobias or post-traumatic stress disorder (PTSD). Memory retrieval is involved in symptom expression and maintenance of these disorders, while memory extinction is believed to be the underlying mechanism of behavioral exposure therapy of anxiety disorders. There is abundant evidence that stress and stress hormones can reduce memory retrieval of emotional information, whereas they enhance memory consolidation of extinction training. In this study we aimed at investigating if stress affects these memory processes in a fear conditioning paradigm in healthy human subjects. On day 1, fear memory was acquired through a standard differential fear conditioning procedure. On day 2 (24h after fear acquisition), participants either underwent a stressful cold pressor test (CPT) or a control condition, 20 min before memory retrieval testing and extinction training. Possible prolonged effects of the stress manipulation were investigated on day 3 (48 h after fear acquisition), when memory retrieval and extinction were tested again. On day 2, men in the stress group showed a robust cortisol response to stress and showed lower unconditioned stimulus (US) expectancy ratings than men in the control group. This reduction in fear memory retrieval was maintained on day 3. In women, who showed a significantly smaller cortisol response to stress than men, no stress effects on fear memory retrieval were observed. No group differences were observed with respect to extinction. In conclusion, the present study provides evidence that stress can reduce memory retrieval of conditioned fear in men. Our findings may contribute to the understanding of the effects of stress and glucocorticoids on fear symptoms in anxiety disorders and suggest that such effects may be sex-specific.

Reward learning as a potential target for pharmacological augmentation of cognitive remediation for schizophrenia: a roadmap for preclinical development

Rationale: Impaired cognitive abilities are a key characteristic of schizophrenia. Although currently approved pharmacological treatments have demonstrated efficacy for positive symptoms, to date no pharmacological treatments successfully reverse cognitive dysfunction in these patients. Cognitively-based interventions such as cognitive remediation (CR) and other psychosocial interventions however, may improve some of the cognitive and functional deficits of schizophrenia. Given that these treatments are time-consuming and labor-intensive, maximizing their effectiveness is a priority. Augmenting psychosocial interventions with pharmacological treatments may be a viable strategy for reducing the impact of cognitive deficits in patients with schizophrenia.

Objective: We propose a strategy to develop pharmacological treatments that can enhance the reward-related learning processes underlying successful skill-learning in psychosocial interventions. Specifically, we review clinical and preclinical evidence and paradigms that can be utilized to develop these pharmacological augmentation strategies. Prototypes for this approach include dopamine D1 receptor and α7 nicotinic acetylcholine receptor agonists as attractive targets to specifically enhance reward-related learning during CR.

Conclusion: The approach outlined here could be used broadly to develop pharmacological augmentation strategies across a number of cognitive domains underlying successful psychosocial treatment.

Stress impairs retrieval of extinguished and unextinguished associations in a predictive learning task

Recovery effects which can frequently be observed after a seemingly successful extinction procedure indicate that extinction does not lead to an erasure of the memory trace. Investigating factors which modulate the retrieval of extinction memory is highly relevant for basic science and clinical applications alike. This study investigated the effect of stress on the retrieval of extinguished and unextinguished stimulus-outcome associations in a predictive learning task. In this task, participants had to imagine being the doctor of a patient who sometimes suffers from stomach trouble after meals in his favorite restaurants. They were presented with different food stimuli while having to predict the occurrence or non-occurrence of stomach trouble. As extinction memory is modulated by context, we manipulated contextual cues so that initial acquisition of critical associations occurred in context (restaurant frame) A on day one, whereas associations were reversed in context B (extinction, day two). On the third day, participants were either stressed (exposed to the socially evaluated cold pressor task (SECPT); n=21) or subjected to a control condition (n=21) shortly before extinction memory retrieval was tested (in contexts A and B). Salivary cortisol and blood pressure measures as well as subjective ratings indicated that stress induction was successful. When retrieval of extinguished associations was tested on day three, participants' predictions reflected a renewal effect, as indicated by stronger recovery of responding in the acquisition context compared to the extinction context. Compared to controls, stressed participants showed impaired retrieval of extinguished and unextinguished associations. Contextual cues abolished the stress-induced memory impairment for unextinguished but not for extinguished associations. These findings might help to explain why stress leads to the reoccurrence of symptoms in affective disorders.

Non-response of cortisol during stressful exposure therapy in patients with obsessive-compulsive disorder--preliminary results

Exposure with response prevention (ERP) is an established treatment for patients with obsessive-compulsive disorder (OCD) and also an interesting model to characterize neuroendocrine response to psychological stress. However, so far few studies have assessed hypothalamic-pituitary-adrenocortical (HPA) function during ERP and results are inconsistent. In 15 patients with OCD we repeatedly measured salivary cortisol and subjective units of distress (SUD) on two consecutive afternoons. The first day served as a comparison condition; on the second day the very first session of ERP took place. While SUD were significantly increased during ERP versus the comparison day, salivary cortisol was statistically indistinguishable between ERP and comparison conditions before, during and after ERP. Thus, despite considerable psychological stress no increase of cortisol was observed. This response pattern to ERP in OCD patients needs further research.

Can anesthesia trigger delayed-onset posttraumatic stress disorder in veterans?

PURPOSE

The clinical presentation of a 60-year-old Vietnam veteran who developed delayed-onset posttraumatic stress disorder (PTSD) after surgery is presented along with mechanisms for storing traumatic memory and a discussion of the potential contributions of anesthesia and aging to his clinical presentation.

CONCLUSION

Although additional research is needed to clarify the contributions of memory processes, anesthesia, and aging in delayed-onset PTSD, prudent clinicians will be cognizant of a potential correlation and screen patients appropriately.

PRACTICE IMPLICATIONS

A thorough surgical and anesthetic exposure history should be explored in presentations of delayed-onset posttraumatic disorder symptomatology. Additionally, clinicians working with trauma patients who anticipate surgery are uniquely positioned to serve as a liaison between the patient, surgeon, and anesthetist, thereby decreasing the potential for delayed-onset PTSD.

A current overview of cannabinoids and glucocorticoids in facilitating extinction of aversive memories: potential extinction enhancers

Emotional learning is extremely important for the survival of an individual. However, once acquired, emotional associations are not always expressed. The regulation of emotional responses under different environmental conditions is essential for mental health. Indeed, pathologic feelings of fear and anxiety are defining features of many serious psychiatric illness, including post-traumatic stress disorder (PTSD) and specific phobias. The simplest form of regulation of emotional responses is extinction, in which the conditioned response to a stimulus decreases when reinforcement (stimulus) is omitted. In addition to modulating basal anxiety states, recent studies suggest an important role for the endocannabinoid (eCB) and glucocorticoid systems in the modulation of emotional states and extinction of aversive memories in animals. The purpose of this review is to briefly outline the animal models of fear extinction and to describe how these have been used to examine the potential of extinction enhancing agents which specifically alter the eCB and glucocorticoid systems. Pharmacological manipulations of these systems by agents such as cannabinoid or glucocorticoid agonists can enhance the extinction process and avoid the retention of memories which have the potential to trigger trauma. A better understanding of these findings through animal models highlights the possibilities of using combined extinction enhancing agents in exposure-based psychotherapies for anxiety disorders related to inappropriate retention of aversive memories. This article is part of a special issue entitled 'Cognitive Enhancers'.

Functional magnetic resonance imaging correlates of emotional word encoding and recognition in depression and anxiety disorders

BACKGROUND

Major depressive disorder (MDD), panic disorder, and social anxiety disorder are among the most prevalent and frequently co-occurring psychiatric disorders in adults and may be characterized by a common deficiency in processing of emotional information.

METHODS

We used functional magnetic resonance imaging during the performance of an emotional word encoding and recognition paradigm in patients with MDD (n = 51), comorbid MDD and anxiety (n = 59), panic disorder and/or social anxiety disorder without comorbid MDD (n = 56), and control subjects (n = 49). In addition, we studied effects of illness severity, regional brain volume, and antidepressant use.

RESULTS

Patients with MDD, prevalent anxiety disorders, or both showed a common hyporesponse in the right hippocampus during positive (>neutral) word encoding compared with control subjects. During negative encoding, increased insular activation was observed in both depressed groups (MDD and MDD + anxiety), whereas increased amygdala and anterior cingulate cortex activation during positive word encoding were observed as depressive state-dependent effects in MDD only. During recognition, anxiety patients showed increased inferior frontal gyrus activation. Overall, effects were unaffected by medication use and regional brain volume.

CONCLUSIONS

Hippocampal blunting during positive word encoding is a generic effect in depression and anxiety disorders, which may constitute a common vulnerability factor. Increased insular and amygdalar involvement during negative word encoding may underlie heightened experience of, and an inability to disengage from, negative emotions in depressive disorders. Our results emphasize a common neurobiological deficiency in both MDD and anxiety disorders, which may mark a general insensitiveness to positive information.

Pharmacological enhancement of fear reduction: preclinical models

Anxiety disorders have a high prevalence, and despite the substantial advances in the psychological treatment of anxiety, relapse is still a common problem. One approach to improving existing psychological treatments for anxiety has been to develop pharmacological agents that can be used to enhance the processes underlying exposure therapy, which is the most commonly used and empirically validated psychological treatment for anxiety during which individuals are taught to appropriately inhibit fear. Animal models of exposure therapy, particularly fear extinction, have proved to be a very useful way of examining the neural and molecular correlates of fear inhibition, which has in turn led to the identification of numerous drugs that enhance these processes in rats. Several of these drugs have subsequently been tested as novel pharmacological adjuncts to exposure therapy in humans with a range of anxiety disorders. The purpose of this review is to outline the key animal models of exposure therapy and to describe how these have been used to develop potential pharmacological adjuncts for anxiety disorders. Drugs that are currently in clinical use, as well as those currently in the preclinical stages of investigation, are described.

Cognitive behavioral therapy in anxiety disorders: current state of the evidence

A plethora of studies have examined the efficacy and effectiveness of cognitive-behavioral therapy (CBT) for adult anxiety disorders. In recent years, several meta-analyses have been conducted to quantitatively review the evidence of CBT for anxiety disorders, each using different inclusion criteria for studies, such as use of control conditions or type of study environment. This review aims to summarize and to discuss the current state of the evidence regarding CBT treatment for panic disorder, generalized anxiety disorder, social anxiety disorder, obsessive-compulsive disorder, and post-traumatic stress disorder. Overall, CBT demonstrates both efficacy in randomized controlled trials and effectiveness in naturalistic settings in the treatment of adult anxiety disorders. However, due to methodological issues, the magnitude of effect is currently difficult to estimate. In conclusion, CBT appears to be both efficacious and effective in the treatment of anxiety disorders, but more high-quality studies are needed to better estimate the magnitude of the effect.

Pharmacotherapy for anxiety disorders in children and adolescents

Anxiety disorders are the most common mental health diagnoses in youth, and carry risks for ongoing impairments and subsequent development of other psychiatric comorbidities into adulthood. This article discusses considerations for assessment and treatment of anxiety disorders in youth, with a focus on the evidence base of pharmacologic treatment and important clinical considerations to optimize care. We then briefly describe the impact of anxiety on neuronal elements of fear circuitry to highlight how treatments may ameliorate impairments through enhanced plasticity Overall, pharmacotherapy for anxiety disorders is effective in improving clinical symptoms, particularly in combination with psychotherapy. Response is typically seen within several weeks, yet longitudinal studies are limited. Selective serotonin reuptake inhibitors are thought to be relatively safe and effective for acute treatment of several classes of anxiety disorders in youth, with increasing evidence supporting the role of neuronal plasticity in recovery.

Neuronal correlates of extinction learning are modulated by sex hormones

In emotional learning tasks, sex differences, stress effects and an interaction of these two moderators have often been observed. The sex hormones estradiol (E2) and progesterone (P4) vary over the menstrual cycle. We tested groups with different sex hormone status: 39 men, 30 women in the luteal phase (LU, high E2+P4) and 29 women taking oral contraceptives (OC, low E2+P4). They received either 30 mg cortisol or placebo prior to instructed differential fear conditioning consisting of neutral conditioned stimuli (CS) and an electrical stimulation (unconditioned stimulus; UCS). One figure (CS+) was paired with the UCS, the other figure (CS-) never. During extinction, no electrical stimulation was administered. Regarding fear acquisition, results showed higher skin conductance and higher brain responses to the CS+ compared to the CS- in several structures that were not modulated by cortisol or sex hormones. However, OC women exhibited higher CS+/CS- differentiations than men and LU women in the amygdala, thalamus, anterior cingulate and ventromedial prefrontal cortex during extinction. The suppression of endogenous sex hormones by OC seems to alter neuronal correlates of extinction. The observation that extinction is influenced by the current sex hormone availability is relevant for future studies and might also be clinically important.

Magnesium deficiency induces anxiety and HPA axis dysregulation: modulation by therapeutic drug treatment

Preclinical and some clinical studies suggest a relationship between perturbation in magnesium (Mg²⁺) homeostasis and pathological anxiety, although the underlying mechanisms remain largely unknown. Since there is evidence that Mg²⁺ modulates the hypothalamic-pituitary adrenal (HPA) axis, we tested whether enhanced anxiety-like behaviour can be reliably elicited by dietary Mg²⁺ deficiency and whether Mg²⁺ deficiency is associated with altered HPA axis function. Compared with controls, Mg²⁺ deficient mice did indeed display enhanced anxiety-related behaviour in a battery of established anxiety tests. The enhanced anxiety-related behaviour of Mg²⁺ deficient mice was sensitive to chronic desipramine treatment in the hyponeophagia test and to acute diazepam treatment in the open arm exposure test. Mg²⁺ deficiency caused an increase in the transcription of the corticotropin releasing hormone in the paraventricular hypothalamic nucleus (PVN), and elevated ACTH plasma levels, pointing to an enhanced set-point of the HPA axis. Chronic treatment with desipramine reversed the identified abnormalities of the stress axis. Functional mapping of neuronal activity using c-Fos revealed hyper-excitability in the PVN of anxious Mg²⁺ deficient mice and its normalisation through diazepam treatment. Overall, the present findings demonstrate the robustness and validity of the Mg²⁺ deficiency model as a mouse model of enhanced anxiety, showing sensitivity to treatment with anxiolytics and antidepressants. It is further suggested that dysregulations in the HPA axis may contribute to the hyper-emotionality in response to dietary induced hypomagnesaemia.

This article is part of a Special Issue entitled ‘Anxiety and Depression’.

Glucocorticoids are required for extinction of predator stress-induced hyperarousal

BACKGROUND

The role of glucocorticoids in extinction of traumatic memories has not been fully characterized despite its potential as a therapeutic target for acquired posttraumatic stress disorder (PTSD). The predator stress paradigm allows us to determine whether glucocorticoids mediate the extinction of both context-dependent and context-independent fear memories.

METHODS

Male C57BL/6J mice were exposed to a predator (cat) then repeatedly exposed to the predator stress context in the absence of the cat. Context-dependent (associative) fear memory was assessed as suppression of activity during re-exposure to the predator stress context without the cat (extinction trials). Context-independent fear (non-associative) was assessed seven days after extinction trials using measures of hyperarousal and anxiety-like behaviours in environments unlike the predator stress context. To assess the role of glucocorticoids, mice were injected with metyrapone (50mg/kg) 90 min prior to extinction trials in predator stressed mice and context-dependent and context-independent fear memories were assessed. Finally, metyrapone-treated predator stressed mice were injected with corticosterone (5 or 10mg/kg) immediately following extinction trials and context-dependent and context-independent fear memories were assessed.

RESULTS

Repeated re-exposure to the predator stress context without the cat present extinguished context-dependent fear memory, and also reduced hyperarousal, a generalized, chronic PTSD-like symptom. We show that extinction of context-independent predator stress-induced hyperarousal is dependent on endogenous glucocorticoids during the extinction trials. Furthermore, the inhibition of extinction by metyrapone on startle amplitude was reduced by exogenous administration of corticosterone following extinction trials. Overall, these data implicate glucocorticoids in the extinction of hyperarousal, a core symptom of PTSD.