Timing matters: Endogenous cortisol mediates benefits from early-day psychotherapy

Resilience by design: How nature, nurture, environment, and microbiome mitigate stress and allostatic load

Resilience to psychological stress is defined as adaption to challenging life experiences and not the absence of adverse life events. Determinants of resilience include personality traits, genetic/epigenetic modifications of genes involved in the stress response, cognitive and behavioral flexibility, secure attachment with a caregiver, social and community support systems, nutrition and exercise, and alignment of circadian rhythm to the natural light/dark cycle. Therefore, resilience is a dynamic and flexible process that continually evolves by the intersection of different domains in human’s life; biological, social, and psychological. The objective of this minireview is to summarize the existing knowledge about the multitude factors and molecular alterations that result from resilience to stress response. Given the multiple contributing factors in building resilience, we set out a goal to identify which factors were most supportive of a causal role by the current literature. We focused on resilience-related molecular alterations resulting from mind-body homeostasis in connection with psychosocial and environmental factors. We conclude that there is no one causal factor that differentiates a resilient person from a vulnerable one. Instead, building resilience requires an intricate network of positive experiences and a healthy lifestyle that contribute to a balanced mind-body connection. Therefore, a holistic approach must be adopted in future research on stress response to address the multiple elements that promote resilience and prevent illnesses and psychopathology related to stress allostatic load.

Sleep and dreaming in the light of reactive and predictive homeostasis

Dreams are often viewed as fascinating but irrelevant mental epihenomena of the sleeping mind with questionable functional relevance. Despite long hours of oneiric activity, and high individual differences in dream recall, dreams are lost into oblivion. Here, we conceptualize dreaming and dream amnesia as inherent aspects of the reactive and predictive homeostatic functions of sleep. Mental activity during sleep conforms to the interplay of restorative processes and future anticipation, and particularly during the second half of the night, it unfolds as a special form of non-constrained, self-referent, and future-oriented cognitive process. Awakening facilitates constrained, goal-directed prospection that competes for shared neural resources with dream production and dream recall, and contributes to dream amnesia. We present the neurophysiological aspects of reactive and predictive homeostasis during sleep, highlighting the putative role of cortisol in predictive homeostasis and forgetting dreams. The theoretical and methodological aspects of our proposal are discussed in relation to the study of dreaming, dream recall, and sleep-related cognitive processes.

The Impact of Sleep on Fear Extinction

Sleep plays a crucial role in the consolidation of memories, including those for fear acquisition and extinction training. This chapter reviews findings from studies testing this relationship in laboratory, naturalistic, and clinical settings. While evidence is mixed, several studies in humans have linked fear and extinction recall/retention to both rapid eye-movement and slow wave sleep. Sleep appears to further aid in the processing of both simulated and actual trauma and improves psychotherapeutic treatment outcomes in those with anxiety and trauma- and stressor-related disorders. This chapter concludes with a discussion of the current challenges facing sleep and emotional memory research in addition to suggestions for improving future research.

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

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

The impact of hormonal contraceptives on anxiety treatments: From preclinical models to clinical settings

Exposure therapy is a central component of the first-line treatment for anxiety disorders, a common mental health condition that is twice as prevalent in women relative to men. A key underlying mechanism of exposure therapy is fear extinction, which is an active learning process supported by a neural circuitry that is highly regulated by ovarian hormones. This review synthesises research examining the impact of hormonal contraceptives on laboratory fear extinction tasks in female rats and women, and on exposure therapy in women with anxiety disorders. The evidence indicates that hormonal contraceptives have a detrimental impact on fear extinction and exposure therapy that is consistent across species, and from laboratory to clinical settings. Candidate pathways by which hormonal contraceptives impede fear extinction and exposure therapy include suppression of endogenous ovarian hormones and glucocorticoids, and downregulation of signalling pathways that support extinction learning. Key areas of focus for future research are discussed.

Why Does Psychotherapy Work and for Whom? Hormonal Answers

The questions of for whom and why psychotherapy is effective have been the focus of five decades of research. Most of this knowledge is based on self-report measures. Following the biopsychosocial model of mental disorders, this article explores the potential of hormones in answering these questions. The literature on cortisol, oxytocin, and oestradiol in psychotherapy was systematically searched, focusing on (a) baseline hormonal predictors of who may benefit from psychotherapy and (b) hormonal changes as indicators of therapeutic change. The search was limited to depression and anxiety disorders. In sum, the findings show that, of all three hormones, the role of cortisol is most established and that both cortisol and oxytocin are implicated in psychotherapy, although a causal role is still waiting to be demonstrated. Moreover, there is a differential role of hormones in the psychotherapy of depression versus anxiety. The directions of research mapped in this article may elucidate how psychotherapy can be selected to match patients’ endocrine states and how hormonal levels can be manipulated to improve outcomes.

Socioemotional deficit and HPA axis time response in high compulsive rats selected by schedule-induced polydipsia

Compulsivity is a failure to stop an ongoing behavior that has become inappropriate to the situation and is recognized as a transdiagnostic trait present in different neuropsychiatric disorders. The implication of motivation and emotion, as well as the stress response in compulsive population has not been fully understood. We assessed the motivation to reward and cues, the emotional response in different contexts and the hypothalamic-pituitary-adrenal (HPA) axis response in rats selected by a preclinical model of compulsive behavior. Firstly, high (HD) or low (LD) drinkers were selected according to their drinking behavior on schedule-induced polydipsia (SIP). Then, we assessed motivation by the propensity to attribute incentive salience to rewards on Pavlovian Conditioned Approach (PavCA) and motivation to gain reward on Progressive Ratio Schedule of Reinforcement (PRSR). Emotion was measured by Social Dominance on the Tube Test (SDTT) and emotional memory on Passive Avoidance (PA). Plasma corticosterone (CORT) levels in response to SIP were assessed. HD rats showed a socioemotional deficit by fewer victories on the SDTT, and an increased latency to enter the dark compartment on the PA. No differences were found between groups regarding to motivational assessment. Moreover, HD rats revealed a blunted time response in the increase of CORT levels at 45 min after SIP compared to LD rats. The findings show that the compulsive phenotype of HD rats exhibit less social dominance, more resistance to extinction and a differential CORT time response to SIP. These findings may contribute to highlight the relevance of assessing socioemotional behaviors and stress response for a better characterization of the vulnerability to compulsive spectrum disorders.

Stress Hormones as Predictors of Response to Cognitive Behavior Therapy in Panic Disorder

OBJECTIVE

Data regarding the potential association between the outcome of psychotherapy of panic disorder (PD) and biological parameters are few. In 21 (16 females) consecutively referred, medication-free, acutely ill PD outpatients, without comorbidities, except agoraphobia, we systematically explored for potential neuroendocrine and clinical correlates of response to a brief cognitive behavior therapy (CBT).

METHODS

Cortisol and adrenocorticotropic hormone (ACTH) basal plasma levels were measured. Measures of psychopathology: (a) Symptom Checklist-90-Revised (SCL-90-R), (b) Clinical Global Impressions-Improvement (CGI-I) Scale, (c) Agoraphobic Cognitions Questionnaire (ACQ), and (d) Mobility Inventory (MI)-alone subscale.

RESULTS

Nonresponders to CBT (CGI-I >2; N = 6) - as compared to the responders (CGI-I ≤2; N = 15) - demonstrated significantly higher cortisol and ACTH basal plasma concentrations. These differences were much stronger when only female patients (nonresponders = 4; responders = 12) were taken into consideration. Regarding psychopathology, nonresponders to CBT suffered from more severe agoraphobia (MI-alone) at baseline. On the contrary, more intense manifestations of anger (SCL-90-R) at baseline were associated with a better treatment outcome. Response to CBT was associated with significant reductions in all SCL-90-R subscales, more pronounced for "phobic anxiety" and "anxiety" subscales.

CONCLUSIONS

This study suggests that in acutely ill, medication-free PD patients, response to CBT may be associated with certain hormonal and clinical parameters at baseline.

Waxing and waning: The roles of chronotype and time of day in predicting symptom fluctuations in obsessive-compulsive disorder using a daily-monitoring design

Obsessive-compulsive disorder (OCD) symptoms fluctuate throughout the day, but scientists are not sure what underlies these fluctuations. One factor which may explain how OCD symptoms wax and wane throughout the day is alertness. Increased alertness is associated with greater inhibitory control, a factor which plays a significant role in patients' ability to overcome their OCD symptoms. The current study examined the relationship between chronotype (morningness/eveningness preference, a measure of alertness) and within-day OCD symptom severity fluctuations. We hypothesized that increased alertness leads to better inhibitory abilities and, therefore, reduced OCD symptoms. OCD Symptoms were measured through 7-days of monitoring in which participants were asked to retrospectively rate their symptoms at several timepoints throughout the day. Chronotype was measured using the Morningness/Eveningness Questionnaire (MEQ). Consistent with our hypotheses, results revealed an interaction between chronotype and time of day, such that those with an eveningness preference tended to have worse symptoms in the morning, and vice versa. In addition, we also report novel findings regarding the effect of bedtime, sleep duration, and sleep quality on symptom severity the next day. Taken together, these findings suggest that alertness may modulate OCD symptom severity throughout the day such that individuals experience more severe symptoms during times of low alertness. The clinical and theoretical implications of these findings are discussed.

Sleep quality and outcome of exposure therapy in adults with social anxiety disorder

INTRODUCTION

Poor sleep is prevalent among individuals with social anxiety disorder (SAD) and may negatively affect exposure therapy outcomes. Poor sleep may impair memory and learning, and thus compromise fear extinction learning thought to take place in exposure therapy. We examined poor sleep as a predictor of exposure therapy outcomes for SAD and the moderating role of d-cycloserine (DCS) on this relationship.

METHODS

Participants were 152 individuals with a primary diagnosis of SAD. As part of a randomized clinical trial evaluating the efficacy of DCS for enhancing the effects of exposure therapy, they completed self-report baseline measure of sleep quality, and self-report sleep diaries assessing sleep duration (total sleep time [TST]) and sleep quality the nights before and after treatment sessions.

RESULTS

Poorer baseline sleep quality was significantly associated with slower improvement over time and worse symptom outcomes at the end of treatment and follow-up after controlling for baseline symptoms of depression and social anxiety. Greater TST the night before treatment predicted lower SAD symptoms at the next session, after controlling for symptoms at the previous session. There was no relation between prior or subsequent night sleep quality on symptoms at the next session. No associations were moderated by DCS.

CONCLUSIONS

We replicated and extended findings indicating that poor sleep quality is associated with poorer exposure therapy outcomes for SAD. Assessing for sleep difficulties before treatment initiation and incorporating sleep interventions into treatment may enhance exposure therapy outcomes for SAD.

A randomized, double-blind, placebo-controlled trial of hydrocortisone augmentation of Prolonged Exposure for PTSD in U.S. combat veterans

OBJECTIVE

Cognitive behavioral therapies such as Prolonged Exposure (PE) are considered first line treatments for posttraumatic stress disorder (PTSD). Nonetheless, many continue to experience significant symptoms following treatment and there is interest in enhancing treatment effectiveness. Glucocorticoid alterations in PTSD are well documented, and these steroids have been shown to enhance extinction learning.

METHODS

Augmentation of PE with the synthetic glucocorticoid hydrocortisone (HCORT) was tested in a randomized, double-blind, placebo-controlled trial in 60 veterans of wars in Iraq or Afghanistan with PTSD (NCT01525680). Participants ingested 30 mg oral HCORT or placebo 30 min prior to exposure sessions.

PRIMARY OUTCOME MEASURE

PTSD severity assessed by the CAPS; secondary outcome measures: self reported PTSD symptoms assessed by the PDS and depression assessed by the BDI; all administered at pretreatment, posttreatment, and 3-month follow up.

RESULTS

Across conditions, there was a robust effect of PE over time. An intent-to-treat analysis showed that HCORT did not measurably improve PTSD symptoms or secondary outcomes. However, exploratory analyses indicated that veterans with mild TBI exposure and current postconcussive symptoms showed a greater reduction in hyperarousal symptoms following PE treatment with HCORT augmentation. Additionally, veterans with higher baseline glucocorticoid sensitivity showed a greater reduction in avoidance symptoms with HCORT augmentation.

CONCLUSIONS

Treatment matching based on cognitive or biological vulnerabilities might lead to greater efficacy of PE with glucocorticoid augmentation.

But first, coffee: The roles of arousal and inhibition in the resistance of compulsive cleansing in individuals with high contamination fears

Inhibition plays a crucial role in reducing intrusive thoughts and compulsive behaviors, such as handwashing, in response to the feeling of disgust. The current study examines whether manipulating arousal can facilitate inhibition and the resistance of compulsive cleansing. Forty-seven participants with high contamination fears were recruited for this study. Participants were divided into a caffeine group or a no-caffeine group. Participants touched a potentially contaminated and disgusting stimulus ("dirty" diapers) and were asked to wait as long as they could before washing their hands. Only the caffeine group exhibited greater pre-post stop-signal reaction time improvement in the stop-signal task, indicating improved inhibition. Participants in the caffeine group exhibited significantly lower subjective distress and urges-to-wash their hands both after touching the stimulus and while waiting to engage in the cleansing behavior. Similarly, the caffeine group resisted the urge to compulsively cleanse for about twice as long as those in the no-caffeine group. Time spent washing, subjective distress levels, and urge-to-wash levels after participants washed their hands were similar between groups. The current findings support the notion that increased arousal improves inhibition, which may play a role in improving our ability to resist intrusive disgust and compulsive cleansing behaviors.

Cortisol, DHEA and DHEA-S during exposure therapy in patients with obsessive-compulsive disorder - secretion patterns and prediction of treatment response

The cortisol response in patients with obsessive-compulsive disorder (OCD) during exposure with response prevention (ERP), a stressful but very effective psychotherapeutic treatment, has shown contradictory findings in three prior studies with low sample sizes. In a larger cohort of 51 patients with OCD we repeatedly measured subjective units of distress (SUD) and the adrenocortical stress hormones cortisol, dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEA-S) in saliva during the very first session of ERP and on the day before. Expectedly, SUD were increased on the ERP day before the session and further rose during ERP, but salivary cortisol and DHEA were statistically indistinguishable from the comparison condition. Interestingly, DHEA-S was significantly elevated throughout the ERP versus the comparison day, but did not further increase in acute response to ERP. According to an explorative analysis in a subsample, hormone levels on the comparison or the ERP day did not predict anti-OCD treatment response one month later. These results corroborate our prior findings of cortisol non-response despite considerable subjective stress in ERP. The role of DHEA-S in anticipatory anxiety and the effects of augmentative cortisol therapy in ERP need further study.

Sleep duration and timing in obsessive-compulsive disorder (OCD): evidence for circadian phase delay

OBJECTIVES

To investigate potential delays in endogenous melatonin in individuals with obsessive-compulsive disorder (OCD).

METHODS

First, data are presented for 15 individuals with OCD and matched healthy controls. Next, nine additional participants with OCD who did not have matched controls were added, resulting in a sample of 24 individuals with OCD. All participants were assessed for sleep and circadian rhythm disturbance. Dim light melatonin onset (DLMO) was derived from salivary melatonin and was used in conjunction with sleep diaries, interview measures, and questionnaires. A subset of the OCD group (n = 16) also used actigraphy.

RESULTS

In sum, 42% percent (10/24) of the patients with OCD met the criteria for delayed sleep-wake phase disorder (DSWPD) in comparison to 0% in the control sample. DLMO was significantly later in individuals with OCD compared to controls. DLMO and bedtime were not significantly associated with the severity of obsessive-compulsive symptoms or negative affect.

CONCLUSIONS

Replication of the findings presented herein, particularly the DLMO results, is warranted. Further, there are now three studies showing that nearly ½ of individuals with OCD meet criteria for a DSWPD. Future studies can explore the mechanisms underlying these connections and the implications of this comorbidity. These findings may increase our understanding of OCD and inform future interventions.

Psychoneuroendocrinology and Clinical Psychology

Hormones impact on cognition, emotions, and behaviour. Given that mental disorders are defined by abnormalities in these very same domains, clinical psychologists may benefit from learning more about alterations in endocrine systems, how they can contribute to symptoms commonly experienced by patients, and how such knowledge may be put to use in clinical practice.

The aim of the present scientific update was to provide a brief overview of endocrine research relevant to the aetiology, diagnostics, and treatment of mental disorders, including some of the latest studies in this area.

Hormones appear to be intrinsic to the development and maintenance of mental disorders. Oxytocin is involved in social cognition and behaviour and as such may be relevant to mental disorders characterised by social deficits (e.g., autism spectrum disorder and schizophrenia). Stress and sex steroids exert demonstrable effects on mood and cognition. In patients with depression and anxiety disorders, initial attempts to lower/enhance such hormones have thus been undertaken within conventional therapies in order to improve outcomes. Finally, hunger and satiety hormones may be involved in the vicious circle of dysfunctional eating behaviours and weight loss/gain in anorexia or bulimia nervosa.

Three conclusions can be drawn from this review: First, endocrine research should be considered when patients and clinicians are developing multidimensional illness models together. Second, endocrine markers can complement conventional assessments to provide a more comprehensive account of a patient’s current state. Third, endocrine testing may guide treatment choices and inform the development of novel treatments.

Hormones are intrinsic to the development and maintenance of mental disorders

Endocrine research should be incorporated into multidimensional illness models

Endocrine markers can complement conventional diagnostic assessments

Endocrine testing may guide treatment choices and inform the development of new treatments

Cortisol administration after extinction in a fear-conditioning paradigm with traumatic film clips prevents return of fear

Cortisol is a stress hormone and potent modulator of learning and memory processes. If administered after learning, cortisol can enhance memory consolidation. Yet it is unknown whether cortisol administration after fear extinction learning strengthens extinction memory. Extinction is a crucial mechanism underlying psychotherapy of posttraumatic stress disorder (PTSD). The present study examined whether extinction can be enhanced by administering cortisol after extinction training. In a registered, randomized, double-blind and placebo controlled trial, 50 healthy participants were exposed to a differential fear-conditioning paradigm with neutral faces as conditioned stimuli (CS) and traumatic film clips as unconditioned stimuli (US). They received either cortisol (n = 25) or placebo (n = 25) immediately after extinction. The cortisol group showed less fear during a return of fear manipulation (reinstatement) evidenced by attenuated fear potentiated startle responses and US-expectancy ratings than the placebo group. Results indicate that cortisol administration after fear extinction strengthens extinction memory and suggest that it might be advantageous to administer cortisol subsequent to successful exposure treatment sessions.

The physiological significance of the circadian dynamics of the HPA axis: Interplay between circadian rhythms, allostasis and stress resilience

Circadian time-keeping mechanisms preserve homeostasis by synchronizing internal physiology with predictable variations in the environment and temporally organize the activation of physiological signaling mechanisms to promote survival and optimize the allocation of energetic resources. In this paper, we highlight the importance of the robust circadian dynamics of allostatic mediators, with a focus on the hypothalamic-pituitary-adrenal (HPA) axis, for the optimal regulation of host physiology and in enabling organisms to adequately respond and adapt to physiological stressors. We review studies showing how the chronic disruption of circadian rhythms can result in the accumulation of allostatic load, which impacts the appropriate functioning of physiological systems and diminishes the resilience of internal systems to adequately respond to subsequent stressors. A careful consideration of circadian rhythm dynamics leads to a more comprehensive characterization of individual variability in allostatic load and stress resilience. Finally, we suggest that the restoration of circadian rhythms after pathological disruption can enable the re-engagement of allostatic mechanisms and re-establish stress resilience.

Glucocorticoid-induced enhancement of extinction-from animal models to clinical trials

Extensive evidence from both animal model and human research indicates that glucocorticoid hormones are crucially involved in modulating memory performance. Glucocorticoids, which are released during stressful or emotionally arousing experiences, enhance the consolidation of new memories, including extinction memory, but reduce the retrieval of previously stored memories. These memory-modulating properties of glucocorticoids have recently received considerable interest for translational purposes because strong aversive memories lie at the core of several fear-related disorders, including post-traumatic stress disorder and phobias. Moreover, exposure-based psychological treatment of these disorders relies on successful fear extinction. In this review, we argue that glucocorticoid-based interventions facilitate fear extinction by reducing the retrieval of aversive memories and enhancing the consolidation of extinction memories. Several clinical trials have already indicated that glucocorticoids might be indeed helpful in the treatment of fear-related disorders.

How stress and glucocorticoids timing-dependently affect extinction and relapse

In recent years, various research groups aimed to augment extinction learning (the most important underlying mechanism of exposure therapy) using glucocorticoids (GCs), in particular the stress hormone cortisol. In this review, we introduce the STaR (Stress Timing affects Relapse) model, a theoretical model of the timing-dependent effects of stress/GCs treatment on extinction and relapse. In particular, we show that (1) pre-extinction stress/GCs promote memory consolidation in a context-independent manner, making extinction memory more resistant to relapse following context change. (2) Post-extinction stress also enhances extinction consolidation, but in a context-bound manner. These differences may result from the timing-dependent effects of cortisol on emotional memory contextualization. At the neural level, extinction facilitation is reflected in alterations in the amygdala-hippocampal-prefrontal cortex network. (3) Stress/GCs before a retrieval test impair extinction retrieval and promote relapse. This may result from strengthening amygdala signaling or disruption of the inhibitory functioning of the prefrontal cortex. The STaR model can contribute to the understanding and prevention of relapse processes.

Coordination between Prefrontal Cortex Clock Gene Expression and Corticosterone Contributes to Enhanced Conditioned Fear Extinction Recall

Post-traumatic stress disorder (PTSD) is associated with impaired conditioned fear extinction learning, a ventromedial prefrontal cortex (vmPFC)-dependent process. PTSD is also associated with dysregulation of vmPFC, circadian, and glucocorticoid hormone function. Rats have rhythmic clock gene expression in the vmPFC that requires appropriate diurnal circulatory patterns of corticosterone (CORT), suggesting the presence of CORT-entrained intrinsic circadian clock function within the PFC. We examined the role of vmPFC clock gene expression and its interaction with CORT profiles in regulation of auditory conditioned fear extinction learning. Extinction learning and recall were examined in male rats trained and tested either in the night (active phase) or in the day (inactive phase). Using a viral vector strategy, Per1 and Per2 clock gene expression were selectively knocked down within the vmPFC. Circulating CORT profiles were manipulated via adrenalectomy (ADX) ± diurnal and acute CORT replacement. Rats trained and tested during the night exhibited superior conditioned fear extinction recall that was absent in rats that had knock-down of vmPFC clock gene expression. Similarly, the superior nighttime extinction recall was absent in ADX rats, but restored in ADX rats given a combination of a diurnal pattern of CORT and acute elevation of CORT during the postextinction training consolidation period. Thus, conditioned fear extinction learning is regulated in a diurnal fashion that requires normal vmPFC clock gene expression and a combination of circadian and training-associated CORT. Strategic manipulation of these factors may enhance the therapeutic outcome of conditioned fear extinction related treatments in the clinical setting.

Behavioral interventions to eliminate fear responses

Fear memory underlies anxiety-related disorders, including posttraumatic stress disorder (PTSD). PTSD is a fear-based disorder, characterized by difficulties in extinguishing the learned fear response and maintaining extinction. Currently, the first-line treatment for PTSD is exposure therapy, which forms an extinction memory to compete with the original fear memory. However, the extinguished fear often returns under numerous circumstances, suggesting that novel methods are needed to eliminate fear memory or facilitate extinction memory. This review discusses research that targeted extinction and reconsolidation to manipulate fear memory. Recent studies indicate that sleep is an active state that can regulate memory processes. We also discuss the influence of sleep on fear memory. For each manipulation, we briefly summarize the neural mechanisms that have been identified in human studies. Finally, we highlight potential limitations and future directions in the field to better translate existing interventions to clinical settings.

Glucocorticoid hormones are both a major circadian signal and major stress signal: How this shared signal contributes to a dynamic relationship between the circadian and stress systems

Glucocorticoid hormones are a powerful mammalian systemic hormonal signal that exerts regulatory effects on almost every cell and system of the body. Glucocorticoids act in a circadian and stress-directed manner to aid in adaptation to an ever-changing environment. Circadian glucocorticoid secretion provides for a daily waxing and waning influence on target cell function. In addition, the daily circadian peak of glucocorticoid secretion serves as a timing signal that helps entrain intrinsic molecular clock phase in tissue cells distributed throughout the body. Stress-induced glucocorticoid secretion also modulates the state of these same cells in response to both physiological and psychological stressors. We review the strong functional interrelationships between glucocorticoids and the circadian system, and discuss how these interactions optimize the appropriate cellular and systems response to stress throughout the day. We also discuss clinical implications of this dual aspect of glucocorticoid signaling, especially for conditions of circadian and HPA axis dysregulation.

Hypoventilation Therapy Alleviates Panic by Repeated Induction of Dyspnea

BACKGROUND

Previous research has shown that hypoventilation therapy reduces panic symptoms in part by increasing basal partial pressure of carbon dioxide (PCO₂) levels. We tested an additional pathway by which hypoventilation therapy could exert its therapeutic effects: through repeated interoceptive exposure to sensations of dyspnea.

METHODS

A total of 35 patients with panic disorder were trained to perform exercises to raise their end-tidal PCO₂ levels using a portable capnometry device. Anxiety, dyspnea, end-tidal PCO₂, and respiratory rate were assessed during each exercise across 4 weeks of training. Mixed-model analysis examined whether within-exercise levels of dyspnea were predictive of reduction of panicogenic cognitions.

RESULTS

As expected, within-exercise anxiety and respiratory rate decreased over time. Unexpectedly, PCO₂ dropped significantly from the beginning to the end of exercise, with these drops becoming progressively smaller across weeks. Dyspnea increased and remained consistently above basal levels across weeks. As hypothesized, greater dyspnea was related to significantly lower panicogenic cognitions over time even after controlling for anxiety and PCO₂. Additional exploratory analyses showed that within-exercise increases in dyspnea were related to within-exercise increases in anxiety but were not related to within-exercise increases in PCO₂.

CONCLUSIONS

In support of the interoceptive exposure model, we found that greater dyspnea during hypoventilation exercises resulted in lower panicogenic cognitions even after the effect of PCO₂ was taken into account. The findings offer an additional important target in panic treatment.

Endogenous cortisol reactivity moderates the relationship between fear inhibition to safety signals and posttraumatic stress disorder symptoms

OBJECTIVE

Posttraumatic stress symptoms (PTSS) are commonly associated with impairments in extinguishing fear to signals previously associated with danger, and also with inhibiting fear to safety signals. Previous studies indicate that PTSS are associated with low cortisol activity, and cortisol is shown to facilitate fear extinction. Few studies have examined the influence of cortisol reactivity on fear extinction in PTSS.

METHOD

We used a standardized fear conditioning and extinction paradigm to investigate the relationship between fear extinction and endogenous salivary cortisol activity in participants with high PTSS (n=18), trauma-exposed controls (n=33), and non-trauma-exposed controls (n=27). Skin conductance response (SCR) was used as an index of conditioned responding. Saliva samples were collected at baseline, and 20min post-fear acquisition for basal and reactive cortisol levels, respectively.

RESULTS

PTSS participants demonstrated a slower rate of extinction learning during the early extinction phase. A moderation analysis revealed that cortisol reactivity was a significant moderator between fear inhibition to the safety signal (CS-) during early extinction and PTSS, but not to the threat signal (CS+). Specifically, this interaction was significant in two ways: (1) participants with elevated cortisol reactivity showed lower PTSS as fear inhibition improved; and (2) participants with low cortisol reactivity showed higher PTSS as fear inhibition improved.

CONCLUSION

The findings of the present study show that the relationship between fear inhibition and cortisol reactivity is complex, and suggest that cortisol reactivity shapes safety signal learning in PTSS.