Improving Exposure Therapy: Rationale and Design of an International Consortium

The Exposure Therapy Consortium (ETC) was established to advance the science and practice of exposure therapy. To encourage participation from researchers and clinicians, this article describes the organizational structure and activities of the ETC. Initial research working group experiences and a proof-of-principle study underscore the potential of team science and larger-scale collaborative research in this area. Clinical working groups have begun to identify opportunities to enhance access to helpful resources for implementing exposure therapy effectively. This article discusses directions for expanding the consortium's activities and its impact on a global scale.

The effects of diazepam on fear extinction in nulliparous and primiparous female rats

Benzodiazepines undermine the success of exposure therapy in humans with anxiety disorders, and impair the long-term memory of fear extinction (the laboratory basis of exposure therapy) in rodents. However, most rodent studies on fear extinction and benzodiazepines have been conducted in male rodents. In female rodents, the estrous cycle influences the consolidation of fear extinction memories and sensitivity to benzodiazepines. In addition, pregnancy leads to long-term changes in the neurobiological, hormonal, and behavioural features of fear extinction, as well as the responsivity to benzodiazepines. Therefore, the present experiments examined the impact of benzodiazepines on fear extinction in female rats with and without reproductive experience. Age-matched nulliparous (no reproductive experience) and primiparous (one prior reproductive experience; tested one-month post-weaning) rats received fear conditioning to a discrete cue. The next day, rats were administered the benzodiazepine diazepam (2 mg/kg, s.c), or vehicle, prior to or immediately after extinction training. Rats were then tested the next day, drug free, for extinction retention. Similar to previous findings in males, diazepam impaired extinction retention in both nulliparous and primiparous rats when administered either pre- or post-extinction training. These findings may have potential clinical implications as they suggest that benzodiazepine use in conjunction with exposure therapy may undermine long-term treatment success in women with and without reproductive experience, although this remains to be tested in human populations. Moreover, these findings are theoretically important when considered in light of previous studies showing dissociable mechanisms of fear extinction in females pre- versus post-pregnancy.

Reproductive experience alters the effects of diazepam and fluoxetine on anxiety-like behaviour, fear extinction, and corticosterone levels in female rats

OVERVIEW

Reproductive experience (pregnancy and motherhood) leads to long-term changes in the neurobiological and hormonal features of anxiety in rats and humans. The aim of this study was to examine whether reproductive experience alters the effects of two pharmacological treatments for anxiety, a benzodiazepine (diazepam) and a selective serotonin reuptake inhibitor (fluoxetine), on animal models of anxiety.

METHODS

In Experiment 1, virgin (n = 47) and age-matched mother (n = 50) rats at 1-month post-weaning were injected with diazepam (1.3 mg/kg or 1.7 mg/kg, i.p.) or vehicle, in the proestrus (high estradiol/progesterone/allopregnanolone) or metestrus (low estradiol/progesterone/allopregnanolone) phase of the estrous cycle 30 min prior to the elevated plus maze (EPM). In Experiment 2, virgin (n = 25) and mother rats (n = 20) were administered fluoxetine (10 mg/kg) or vehicle for 2 weeks prior to being tested on a Pavlovian fear conditioning and extinction protocol, and the EPM.

RESULTS

Replicating past research, in virgin rats, the low dose of diazepam produced anxiolytic-like effects in proestrus, but only the high dose was anxiolytic-like in metestrus. In contrast, in mother rats, both doses of diazepam were anxiolytic-like irrespective of estrous phase. Fluoxetine produced anxiogenic-like effects in virgin rats during fear extinction and the EPM, but had no behavioural effects in mothers. In contrast, fluoxetine increased plasma corticosterone levels measured 30-min post-EPM in mothers, but not virgin rats.

CONCLUSIONS

Reproductive experience alters the dose responsivity and efficacy of common anti-anxiety medications in female rats. These findings highlight the importance of considering reproductive status in studies on anxiety and its treatment.

Dissociable role of the basolateral complex of the amygdala in the acquisition and extinction of conditioned fear following reproductive experience in female rats

In female rats and humans, reproductive experience (i.e., pregnancy) alters the behavioral, hormonal and molecular substrates of fear extinction. Here, we assessed whether the role of a central neural substrate of fear extinction, the basolateral amygdala (BLA), also changes following reproductive experience. Nulliparous (virgin) and primiparous (one prior pregnancy) female rats received infusions of the GABAA agonist, muscimol, to temporarily inactivate the BLA prior to fear conditioning or extinction training. In follow up experiments, the BLA was also inactivated immediately after extinction training. BLA inactivation impaired the acquisition and expression of conditioned fear in both nulliparous and primiparous rats. In nulliparous rats, BLA inactivation prior to or immediately after extinction training impaired extinction retention. In contrast, in primiparous rats, BLA inactivation prior to or immediately after extinction training did not impair extinction retention, despite suppressing freezing during extinction training. These results suggest that, consistent with past findings in males, the BLA is a central component of the neural circuitry of fear acquisition and its extinction in virgin female rats. However, after pregnancy, female rats no longer depend on the BLA to extinguish fear, despite requiring the BLA to acquire conditioned fear. Given that fear extinction forms the basis of exposure therapy for anxiety disorders in humans, the present findings may have clinical implications. To improve the efficacy of exposure therapy for anxiety disorders, we may need to target different mechanisms in females dependent on their reproductive history.

The relationship between salivary Fibroblast Growth Factor-2 and cortisol reactivity and psychological outcomes prior to and during the COVID-19 pandemic

Background

Fibroblast growth factor-2 (FGF2) is a biomarker that is associated with depression, anxiety and stress in rodents. In humans, we have previously demonstrated that salivary FGF2 increased following stress in a similar pattern to cortisol, and FGF2 (but not cortisol) reactivity predicted repetitive negative thinking, a transdiagnostic risk factor for mental illness. The current study assessed the relationship between FGF2, cortisol, and mental health before and during the COVID-19 pandemic.

Methods

We employed a longitudinal correlational design using a convenience sample. We assessed whether FGF2 and cortisol reactivity following the Trier Social Stress Task (TSST) were associated with DASS-21 depression, anxiety and stress, measured at the time of the TSST in 2019-20 (n = 87; time 1), and then again in May 2020 during the first wave of COVID-19 in Sydney (n = 34 of the original sample; time 2).

Results

FGF2 reactivity (but not absolute FGF2 levels) at time 1 predicted depression, anxiety, and stress across timepoints. Cortisol reactivity at time 1 was associated with stress over timepoints, and absolute cortisol levels were associated with depression across timepoints.

Limitations

The sample was comprised of mostly healthy participants from a student population, and there was high attrition between timepoints. The outcomes need to be replicated in larger, more diverse, samples.

Conclusions

FGF2 and cortisol may be uniquely predictive of mental health outcomes in healthy samples, potentially allowing for early identification of at-risk individuals.

The impact of the ovarian cycle on anxiety, allopregnanolone, and corticotropin releasing hormone changes after motherhood in female rats and women

Fluctuations in ovarian steroids across the estrous and menstrual cycle in female rats and women, respectively, are associated with changes in anxiety. Pregnancy causes long-term changes to ovarian hormone release, yet research on estrous- and menstrual-related changes in anxiety has focused on reproductively inexperienced females. Therefore, this study assessed whether the impact of estrous and menstrual cycles on anxiety differs pre- versus post-motherhood in female rats (n = 32) and a community sample of women (n = 63). Estrous cycle phase altered anxiety-like behavior in virgin rats, but had no effect in age-matched mother rats tested 1-month post-weaning. In humans, menstrual cycle phase was associated with ecological momentary assessed anxiety and mood in non-mothers, but not mothers; although, the menstrual cycle × reproductive status interaction for anxiety, but not mood, was rendered non-significant with age and cycle length as covariates. These findings suggest that changes in anxiety coincident with cycling hormones is an evolutionarily conserved feature of the estrous and menstrual cycle in rats and women, which is mitigated following motherhood in both species. We identified several potential mechanisms for the observed dissociation in estrous cycle effects on anxiety. Compared to virgin rats, mother rats had a lower peak and blunted decline in circulating allopregnanolone during proestrus, upregulated GABA_A receptor subunit (α1, α2, α5, α4, ß2) mRNA in the ventral hippocampus, and altered corticotropin-releasing hormone mRNA across the estrous cycle in the basolateral amygdala. Together, these findings suggest that the mechanisms underlying anxiety regulation undergo fundamental transformation following pregnancy in female rats and humans.

The relative efficacy and efficiency of single- and multi-session exposure therapies for specific phobia: A meta-analysis

Exposure therapy is the preferred treatment for specific phobia (SP), with evidence supporting its efficacy whether delivered over multiple sessions or as a single session, such as One-Session Treatment. In this meta-analysis, we compared the efficiency and effectiveness of single- and multi-session exposure for SP. PsycINFO, Embase, MEDLINE, and Cochrane were systematically searched for peer-reviewed articles reporting the effects of multi-session (k = 30) and/or single-session (k = 55) in vivo exposure on SP symptoms in clinical populations (n = 1758 participants). A random-effects model was used to synthesise and compare the pre-post treatment effects (Hedges' g) on approach behaviour and self-reported SP symptoms. Mean total treatment time was significantly longer for multi-session exposure than for single-session. There were no significant differences in the pooled effect sizes of single-session and multi-session exposure at post-treatment and follow-up assessments; effect sizes were large for all outcomes. Phobia subtype significantly moderated the effect size for both treatment approaches, although the direction of association differed according to the outcome measures. Results suggest no evidence for differences in the effectiveness of single- and multi-session exposure, but single-session is more time efficient. These outcomes suggest that policies to facilitate access to single-session exposure would be beneficial.

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.

Symptom fluctuation over the menstrual cycle in anxiety disorders, PTSD, and OCD: a systematic review

Anxiety disorders are more prevalent and severe in women than men. Extant research suggests that the menstrual cycle modulates the severity and expression of anxiety symptoms across a range of disorders. The aims of this systematic review were to synthesise the existing literature investigating menstrual phase-related fluctuations in symptoms of anxiety disorders, and related conditions PTSD and OCD, in menstruating women, and to evaluate the methodologies used. PsycINFO and PubMed were searched through to April 2021 for studies that measured and compared symptoms of a diagnosed anxiety disorder, PTSD, or OCD, between at least two menstrual phases. Fourteen studies meeting inclusion criteria were identified. The review revealed evidence for exacerbation of a broad range of symptoms in panic disorder, PTSD, social anxiety disorder, and generalised anxiety disorder, around the weeks prior to and post menses onset, coincident with elevated but declining ovarian hormones, and low hormone levels, respectively. Effects were heterogenous between individuals and different symptom types. Key methodological weaknesses included sub-optimal and inconsistent means of defining and identifying menstrual phases, low sample representativeness, and small sample sizes. Menstrual fluctuations in anxiety symptoms appear to be a feature of anxiety disorders, PTSD, and OCD, but likely only occur in a subset of women. Future research in this field could better manage and account for such heterogeneity by using group-based trajectory modelling in larger sample sizes and using pre-screening to recruit women with known histories of menstrual fluctuation in anxiety symptoms.

The relationship between repetitive negative thinking, sleep disturbance, and subjective fatigue in women with Generalized Anxiety Disorder

Objectives

Fatigue is a prominent symptom of Generalized Anxiety Disorder (GAD). However, the pathways contributing to elevated fatigue in GAD are poorly understood. Sleep disturbance, also prominent in GAD, only partially explains elevated fatigue in GAD. Repetitive negative thinking (RNT) is a cognitive feature of both GAD and sleep disturbance, and RNT has recently also been associated with elevated fatigue. Therefore, this study assessed whether elevated fatigue in GAD is accounted for by a combination of sleep quality and RNT.

Design

Between‐group, correlational design in 64 primarily university‐educated women with and without a GAD diagnosis.

Methods

Women completed self‐report questionnaires assessing RNT experienced in the past few days, previous night’s sleep quality, and current physical and mental fatigue. Hierarchical linear regressions were conducted to assess whether the relationship between GAD status and fatigue is accounted for by RNT and sleep quality.

Results

Women with GAD reported lower sleep quality, and higher RNT and physical and mental fatigue, compared to women without GAD. Sleep quality partly accounted for group differences in both types of fatigue (β’s > −0.4), whereas RNT fully accounted for group differences in both types of fatigue (β’s > 0.29). The relationship between RNT and both types of fatigue was fully accounted for by sleep quality (β’s > −0.39).

Conclusions

These findings indicate that heightened RNT amongst women with GAD may be associated with elevated physical and mental fatigue via its detrimental effects on sleep quality. Interventions that reduce RNT may help to alleviate fatigue symptoms in women with GAD.

Practitioner points

Women with Generalized Anxiety Disorder (GAD) have elevated fatigue and repetitive negative thinking (RNT), and poorer self‐reported sleep quality, relative to women without GAD.

Whereas sleep quality only partially accounts for elevated fatigue in GAD, RNT fully accounts for elevated fatigue, and the relationship between RNT and fatigue is fully accounted for by sleep quality.

These findings provide novel evidence that women with GAD may have elevated fatigue because of the detrimental effects of RNT on sleep.

These findings suggest that targeting RNT in treatment for GAD may help to reduce fatigue in GAD, by improving sleep quality.

Maternal Experience Does Not Predict Fear Extinction and Anxiety-Like Behaviour in Primiparous Rats Post-weaning

Reproductive experience leads to long-lasting changes in anxiety-like behaviour and fear extinction, the laboratory model of exposure therapy for anxiety disorders. For example, fear extinction is influenced by estrous cycle in nulliparous (no reproductive experience) female rats, but this effect is abolished in primiparous (one reproductive experience) females. It is unclear whether such changes are driven by pregnancy, maternal experience of caring for offspring during the postpartum period, or a combination of both experiences. The present study sought to determine the influence of maternal experience (i.e., exposure to pups and mother-pup interactions) on fear extinction in primiparous rats. In Experiment 1, we tested whether pup exposure is necessary to mitigate estrous effects on fear extinction in primiparous rats. Age-matched nulliparous rats, primiparous rats, and primiparous rats who experienced pregnancy but not pup exposure, underwent fear conditioning on day 1 (2 months post-parturition), extinction training during proestrus (high sex hormones) or metestrus (low sex hormones) on day 2, and extinction recall on day 3. Replicating past research, nulliparous rats showed impaired extinction recall when they were extinguished during metestrus compared to proestrus. In contrast, primiparous rats with and without pup exposure showed comparable extinction recall irrespective of estrous phase. In Experiment 2, we assessed whether naturally-occurring variation in mother-pup interactions predict future fear extinction performance and anxiety-like behaviour. During the first week of lactation, primiparous rats were measured for maternal behaviours toward pups. Primiparous rats were then tested on the light-dark box and elevated plus maze to measure anxiety-like behaviour and underwent a fear extinction protocol 1 month post-weaning. We found no significant correlations between maternal behaviour and fear extinction outcomes or anxiety-like behaviour. Our findings suggest that pregnancy, not maternal experience, mitigates the impact of estrous cycle on fear extinction. In addition, natural variation in maternal experience does not appear to contribute to variability in future fear extinction outcomes or anxiety-like behaviour in primiparous rats.

What Pre-clinical Rat Models Can Tell Us About Anxiety Across the Menstrual Cycle in Healthy and Clinically Anxious Humans

PURPOSE OF REVIEW

Anxiety symptoms increase during the peri-menstrual phase of the menstrual cycle in people with anxiety disorders. Whether this reflects a heightened variant of normal menstrual-related changes in psychological states experienced by healthy (i.e. non-anxious) people is unknown. Moreover, menstrual-related change in anxiety symptoms is a poorly understood phenomenon, highlighting a need for pre-clinical models to aid mechanistic discovery. Here, we review recent evidence for menstrual effects on anxiety-like features in healthy humans as a counterpart to recent reviews that have focused on clinically anxious populations. We appraise the utility of rodent models to identify mechanisms of menstrual effects on anxiety and offer suggestions to harmonise methodological practices across species to advance knowledge in this field.

RECENT FINDINGS

Consistent with reports in clinical populations, some evidence indicates anxiety symptoms increase during the peri-menstrual period in healthy people, although null results have been reported, and these effects are heterogeneous across studies and individuals. Studies in rats show robust increases in anxiety during analogous phases of the oestrous cycle. Studies in female rats are useful to identify the evolutionarily conserved biological mechanisms of menstrual-related changes in anxiety. Future experimental approaches in rats should model the heterogeneity observed in human studies to increase alignment across species and advance understanding of the individual factors that increase the propensity to experience menstrual-related changes in anxiety.

The Association Between Salivary FGF2 and Physiological and Psychological Components of the Human Stress Response

Background

Fibroblast Growth Factor 2 (FGF2) is a neurotrophic protein that has been implicated as a biomarker for anxiety and depressive disorders, which comprise a significant component of the global burden of disease. Research using rodents has indicated that FGF2 is part of the stress response, but whether this translates to humans has yet to be investigated. In this study, we aimed to explore the potential role of FGF2 in the human stress response by examining its association with physiological and psychological processes during and following the Trier Social Stress Test (TSST).

Methods

Participants in the active stress experiment (N  =  87) underwent the TSST, provided saliva samples to obtain levels of cortisol and FGF2, and reported on post-event rumination related to the TSST task over the following week. Participants in the no-stress experiment (N  =  25) provided saliva samples for measurement of FGF2 and cortisol across a corresponding time period.

Results

Salivary FGF2 levels changed after the TSST and were associated with the pattern of change in salivary cortisol. Cortisol responses in the active stress condition were blunted in females (relative to males), however, sex did not interact with any other effect. FGF2 reactivity (ie, the magnitude of change over time) was not correlated with cortisol reactivity. Lower FGF2 reactivity following the TSST, but not overall FGF2 levels, or cortisol, was associated with higher fear of negative evaluation, repetitive negative thinking and post-event processing, as well as repetitive negative thinking in the week following the TSST. Participants in the no-stress experiment showed a decrease in cortisol, yet no change in their FGF2 levels.

Conclusion

These findings suggest that FGF2 is involved in the human stress response and higher levels of FGF2 reactivity may be associated with protective cognitive processes following stress exposure.

Mind's eye: The impact of spider presence and cognitive therapy on size estimation biases in spider phobia

The present study assessed the circumstances under which size estimation biases in spider phobia occur, and whether such biases are modifiable by treatment. Women with (n = 67) and without (n = 33) spider phobia approached a spider during a behavioral approach test (BAT). They provided size estimates of the spider both during and shortly after the BAT (with the spider in view, or not in view, respectively). Phobic women then received cognitive therapy or a placebo treatment and one week later they underwent a second BAT and provided size estimates of the same spider during and after the BAT. Phobic women reported larger size estimates than non-phobic women after, but not during, the BAT. Size estimates after, but not during, the BAT correlated with self-reported fear but not avoidance. Size estimates after, but not during, the BAT reduced from the first to second BAT in phobic women; an effect evident in both the cognitive therapy and placebo treatment conditions. Changes in size estimates were not associated with treatment-induced reductions in fear or avoidance. These results suggest that estimation biases in spider phobia are likely driven by non-perceptual processes. The clinical utility of size estimation measures is discussed.

Subjective sleep quality and characteristics across the menstrual cycle in women with and without Generalized Anxiety Disorder

OBJECTIVE

Past studies have found that various psychiatric symptoms fluctuate over the menstrual cycle. Sleep disturbance is a transdiagnostic feature of psychiatric conditions and is associated with several symptoms that exhibit menstrual fluctuations. Although some evidence indicates that subjective sleep quality changes over the menstrual cycle in healthy women, no studies have investigated whether sleep fluctuates over the menstrual cycle in psychiatric populations, other than premenstrual dysphoric disorder.

METHODS

The present study used a mixed between- within-groups design to compare self-reported sleep characteristics (sleep onset latency, number and duration of night-time awakenings, and total sleep time), sleep quality, insomnia symptoms, and daytime sleepiness in women with (n = 31) and without (n = 32) generalized anxiety disorder (GAD) at two time points within a single menstrual cycle - the early-follicular (low ovarian hormones) and mid-luteal (high ovarian hormones) phases.

RESULTS

Women with GAD reported lower sleep quality, more insomnia symptoms, and more daytime sleepiness (η_p² = 0.13-0.14), but comparable sleep characteristics, compared to women without GAD. In both groups, sleep variables remained stable over the menstrual phases examined. Within-person changes in estradiol and progesterone between the two menstrual phases were mostly not associated with within-person changes in sleep variables, except that larger increases in estradiol were associated with a reduction in the number of night-time awakenings from the early-follicular to mid-luteal phases (β = -0.26).

CONCLUSION

These findings indicate that subjective sleep disturbance, unlike other psychiatric symptoms, may not be modulated by the menstrual cycle and ovarian hormones during the phases examined in this study.

It's all about who you know: Memory retention of a rat's cagemates during infancy negatively predicts adulthood hippocampal FGF2

Recent research has demonstrated that individual differences in infant fear memory positively predict adulthood anxiety-like behavior and conditioned fear expression. However, the physiological mechanisms underlying this relationship and the effect of environmental (e.g., social) influences on the stability of this relationship have not been explored. In the present study, we examined whether individual differences in infant fear memory predict levels of endogenous fibroblast growth factor-2 (FGF2; a biomarker of fear/anxiety) in adulthood, and whether the mean memory retention of a rat's cagemates predicts conditioned fear expression and FGF2 in adulthood. We conditioned infant rats to associate a white noise with shock, and tested their memory of the association 1 week later. They were then weaned and randomly assigned to cage/cagemates. In adulthood, rats received weak context conditioning (i.e., a single shock) and were tested for fear of the context the following day. Rats were then euthanized and their brains extracted to measure levels of hippocampal FGF2 protein. Across 2 experiments, an individual rat's fear memory during infancy positively predicted their own fear expression in adulthood, but the mean memory retention of their cagemates did not predict fear expression. In contrast, the mean memory retention of a rat's cagemates during infancy negatively predicted hippocampal FGF2 protein in adulthood, but an individual rat's memory retention did not predict their own levels of FGF2. These data support the idea that variations in the fearfulness of a rat's cagemates predict individual differences on physiological measures in adulthood.

Gender Differences in Adolescent Sleep Disturbance and Treatment Response to Smartphone App-Delivered Cognitive Behavioral Therapy for Insomnia: Exploratory Study

BACKGROUND

Insomnia and sleep disturbance are pervasive and debilitating conditions affecting up to 40% of adolescents. Women and girls are at greater risk of insomnia, yet differences in treatment responsiveness between genders have not been adequately investigated. Additionally, while women report greater symptom severity and burden of illness than men, this discrepancy requires further examination in adolescents.

OBJECTIVE

The purpose of this study was to examine gender differences in sleep symptom profiles and treatment response in adolescents.

METHODS

Digital cognitive behavioral therapy for insomnia (CBT-I) treatment responsiveness, as indexed by changes in Insomnia Severity Index (ISI) and Global Pittsburgh Sleep Quality Index (PSQI) scores, was compared in boys and girls (aged 12-16 years; N=49) who participated in a pilot evaluation of the Sleep Ninja smartphone app. Gender differences in self-reported baseline insomnia symptom severity (ISI), sleep quality (PSQI), and sleep characteristics derived from sleep diaries were also examined.

RESULTS

Compared with boys, we found that girls reported greater symptom severity (P=.04) and nighttime wakefulness (P=.01 and P=.04) and reduced sleep duration (P=.02) and efficiency (P=.03), but not poorer sleep quality (P=.07), more nighttime awakenings (P=.16), or longer time to get to sleep (P=.21). However, gender differences in symptom severity and sleep duration were accounted for by boys being marginally younger in age. Treatment response to CBT-I was equivalent between boys and girls when comparing reductions in symptom severity (P=.32); there was a trend showing gender differences in improvements in sleep quality, but this was not statistically significant (P=.07).

CONCLUSIONS

These results demonstrate the presence of gender differences in insomnia symptoms and severity in adolescents and suggest further research is required to understand gender differences in insomnia symptom profiles to inform the development of gender-specific digital interventions delivered to adolescents.

Gender differences in avoidance and repetitive negative thinking following symptom provocation in men and women with spider phobia

OBJECTIVES

Women's greater prevalence of anxiety disorders compared to men is widely assumed to be partly due to gender differences in cognitive and behavioural factors that perpetuate anxiety, such as repetitive negative thinking (RNT) and avoidance. However, past studies assessing this assumption have not controlled for gender differences in baseline symptom severity, the type of stressful life experiences against which RNT and avoidance are measured, or emotional reactivity to these experiences.

DESIGN

Using a two-group design, the present study controlled for these confounds by comparing avoidance and RNT in relation to a controlled symptom provocation task in spider phobic men and women with equivalent spider fear severity on the Fear of Spiders Questionnaire.

METHODS

Participants engaged in a behavioural approach test (BAT) involving a live spider, during which they were assessed for avoidance (physical proximity to the spider) and subjective distress. Two weeks later, participants reported on their levels of negative affect and RNT experienced during the preceding weeks in relation to the BAT.

RESULTS

Women exhibited greater avoidance and reported greater RNT than men, despite reporting comparable distress and negative affect. Gender remained a significant predictor of avoidance when accounting for distress and also remained a significant predictor of RNT when accounting for depressive symptoms and negative affect.

CONCLUSIONS

These results provide in vivo evidence that heightened avoidance and RNT may perpetuate anxiety symptoms in women independently of gender differences in symptom severity, daily experiences, or emotional reactivity.

PRACTITIONER POINTS

Following symptom provocation, men and women with spider phobia differ in cognitive and behavioural coping responses. Women exhibit greater avoidance and repetitive negative thinking than men, and these differences are not attributable to gender differences in symptom severity or emotional reactivity. These findings provide novel evidence for gender differences in maintaining factors that perpetuate anxiety disorders whilst accounting for confounding factors present in prior research.

Progesterone levels predict reductions in behavioral avoidance following cognitive restructuring in women with spider phobia

BACKGROUND

Ovarian hormones have been implicated as a potential source of variability in the effectiveness of exposure therapy for anxiety disorders in women. Additionally, preclinical studies in healthy women indicate that ovarian hormones are related to cognitive modes of emotion regulation, like cognitive restructuring. The purpose of the current study was to determine whether a relationship exists between endogenous ovarian hormones and the outcomes of cognitive restructuring in clinically anxious women.

METHODS

Ninety women with spider phobia received training in cognitive restructuring or a control task and provided a blood sample for the measurement of serum estradiol and progesterone levels. Behavioral avoidance, using a behavioral approach task with a live spider, and self-reported fear of spiders were measured at baseline and 1-week post-treatment.

RESULTS

The results indicated that heightened levels of progesterone, but not estradiol, at the time of cognitive restructuring predicted greater post-treatment reductions in behavioral avoidance, but not self-reported fear, amongst women who received cognitive restructuring but not those in the control group.

LIMITATIONS

As menstrual cycle phase was not assessed; the present study provides information regarding how the benefits of cognitive therapy are predicted by between-person individual differences in absolute hormone levels, but does not examine the relationship between within-person fluctuations in hormone levels and outcomes.

CONCLUSIONS

These results suggest the effectiveness of cognitive therapy for anxiety disorders in women may differ depending on endogenous levels of progesterone, and raise the possibility that progesterone could be a useful pharmacological adjunct to cognitive therapy.

Hormonal, reproductive, and behavioural predictors of fear extinction recall in female rats

The prevalence, severity and chronicity of anxiety disorders is significantly higher in women compared to men. Exposure therapy, the gold-standard treatment for anxiety disorders, can be modelled in the laboratory through Pavlovian fear extinction. Understanding the factors that influence fear extinction in females may aid in optimising the treatment of anxiety disorders in this population. The aim of the current study was therefore to explore the hormonal, reproductive and behavioural predictors of fear extinction recall in female rats by analysing data from nine published experiments that examined fear extinction in female rats. A hierarchical multiple regression analysis revealed that estrous cycle effects on extinction recall may be modulated by reproductive status. While the estrous phase in which nulliparous (virgin) rats undergo extinction training was predictive of extinction recall, no relationship between estrous phase and extinction recall was found among primiparous (one prior reproductive experience) rats. Moreover, estrous cycle predicted the relationship between early extinction and extinction recall in nulliparous rats, but not primiparous rats. Although reproductive status did not predict extinction recall, primiparous rats exhibited poor extinction recall relative to nulliparous rats extinguished during proestrus, and better extinction recall than nulliparous rats extinguished during metestrus. A faster rate of extinction, and lower fear responses at the end of extinction training were predictive of lower levels of CS-elicited fear during extinction recall in both nulliparous and primiparous female rats, while the length of extinction training was not predictive of extinction recall. The potential theoretical and clinical implications of these findings are discussed.

Physical and mental fatigue across the menstrual cycle in women with and without generalised anxiety disorder

Subjective, disabling fatigue is a common complaint and a key feature of numerous medical conditions, and is a transdiagnostic feature of psychiatric disorders. Despite physical and mental fatigue being associated with functional impairment and reduced quality of life, little is understood about its underlying mechanisms or modulating factors. Women commonly experience exacerbation of other (non-fatigue related) psychiatric symptoms during the luteal phase of the menstrual cycle, and report greater fatigue prevalence compared to men. It is therefore plausible that subjective fatigue may similarly fluctuate across the menstrual cycle. Here we compared physical and mental fatigue in the early-follicular (lower ovarian hormones) and mid-luteal (higher ovarian hormones) phases of a single menstrual cycle, while controlling for sleep disruption, in women with (n = 18) and without (non-anxious; n = 20) generalised anxiety disorder (GAD). As expected, women with GAD reported greater physical and mental fatigue than healthy women. Further, although there were no changes in physical fatigue from the early-follicular to mid-luteal phases in both groups, mental fatigue in non-anxious women increased to levels equivalent to those experienced by their GAD counterparts in the mid-luteal phase. Although salivary levels of estradiol and progesterone increased from the early-follicular to mid-luteal phase, hormones did not significantly predict fatigue in either phase. These findings are consistent with the exacerbations of state anxiety and mood disturbance recognised to occur in the luteal phase of the menstrual cycle. We speculate that increased mental fatigue in the luteal phase may represent a vulnerable period for the development and maintenance of psychiatric disorders, potentially via compromised emotional regulation.

d-Cycloserine and estradiol enhance fear extinction in nulliparous but not primiparous female rats

Female reproductive experience has been shown to alter the hormonal, neurobiological and behavioural features of fear extinction, which is the laboratory basis of exposure therapy. This raises uncertainties as to whether pharmacological agents that enhance fear extinction in reproductively inexperienced females are equally effective in reproductively experienced females. The aim of the current study was therefore to compare the effects of two pharmacological enhancers of fear extinction, d-cycloserine (DCS) and estradiol, between nulliparous (virgin) and primiparous (reproductively experienced) female rats. In Experiment 1, nulliparous and primiparous females received systemic administration of either DCS or saline immediately after extinction training, and were tested for extinction recall the following day. DCS enhanced extinction recall in nulliparous females that showed low levels of freezing at the end of extinction training, but not among those that showed high levels of freezing at the end of extinction training. DCS did not enhance fear extinction in primiparous females, regardless of their level of freezing at the end of extinction training. In Experiment 2, nulliparous and primiparous female rats received systemic administration of either estradiol or vehicle prior to extinction training. Estradiol enhanced extinction recall among nulliparous females, but not primiparous females. Increasing the dose of estradiol administered prior to extinction training did not alter the outcomes in primiparous females (Experiment 3). Together, these findings suggest that reproductive status may be an important individual difference factor associated with the response to pharmacological modulators of extinction in rats. The implications of these findings for the pharmacological augmentation of exposure therapy in clinical populations are discussed.

Fibroblast growth factor-2 enhancement of extinction recall depends on the success of within-session extinction training in rats: a re-analysis

RATIONALE

One approach to improving exposure therapy for anxiety disorders has focused on developing pharmacological adjuncts to enhance extinction, but these efforts have produced modest success in clinical trials. Understanding the factors that predict the efficacy of adjuncts will help to develop personalized treatments for anxiety.

OBJECTIVES

We assessed whether individual differences in within-session extinction (fear reduction during extinction training) predict the extent to which the neurotrophin fibroblast growth factor-2 (FGF2) enhances extinction recall in rats.

METHODS

We re-analyzed data from five experiments that involved administering FGF2 immediately after extinction training; extinction recall was assessed the following day.

RESULTS

Regression analyses revealed that fear responses at the end, but not the start, of extinction training predicted extinction recall in FGF2- but not vehicle-treated rats. Comparisons between FGF2- and vehicle-treated rats that exhibited better or worse extinction recall (determined by a median split in freezing during extinction recall) confirmed that FGF2-treated rats exhibiting better extinction recall had significantly lower freezing at the end of extinction training relative to FGF2-treated rats exhibiting poorer extinction recall. In contrast, vehicle-treated rats did not differ in within-session extinction based on their performance at extinction recall. Finally, even when classified as having poorer extinction recall, FGF2-treated rats had stronger extinction recall than vehicle-treated rats.

CONCLUSIONS

These results suggest that FGF2 may be most effective amongst rats that exhibit the lowest fear responses at the end of extinction training. Furthermore, FGF2 does not appear to exacerbate fear in rats that exhibit minimal fear reduction during extinction training.

Reproductive experience alters the involvement of N-methyl-D-aspartate receptors in fear extinction, but not fear conditioning, in female Sprague Dawley rats

Recently, evidence has emerged showing that the behavioural and hormonal features of fear extinction are altered as a result of reproductive experience in both rats and humans. The current set of experiments sought to determine whether reproductive experience also alters the molecular features of fear extinction. In adult male rats, it has been widely demonstrated that the activation of N-methyl-D-aspartate receptors (NMDAR) is essential for fear extinction. We therefore compared the involvement of NMDAR in fear extinction between nulliparous (virgin) and primiparous (reproductively experienced) female rats. Nulliparous and primiparous females received systemic administrations of either MK-801 (a non-competitive NMDAR antagonist) or saline prior to extinction training. MK-801 was found to impair extinction recall in nulliparous females, but not primiparous females. When the same dose of MK-801 was administered prior to conditioning, both groups of rats showed impaired recall of conditioning the following day. The results of these experiments indicate that the extinction, but not the acquisition of fear, may become NMDAR-independent following reproductive experience.

Low estradiol is linked to increased skin conductance, but not subjective anxiety or affect, in response to an impromptu speech task

Low estradiol is associated with impaired extinction of conditioned physiological fear responses (e.g. skin conductance) in females. As fear extinction is the laboratory basis of exposure therapy for anxiety disorders, it has been speculated that estradiol may be related to the effectiveness of treatment for anxiety. The present study extended past research by examining whether estradiol is related to physiological and subjective fear responses during the impromptu speech task, where participants perform a surprise speech to camera. This task elicits psychosocial fear, and thus has relevance for social anxiety disorder (SAD). We used a quasi-experimental design with two groups of women: 39 naturally cycling women, and 19 women taking hormonal contraceptives. Based on the measured serum levels, naturally cycling women were further divided into women with higher- vs. lower estradiol levels. Compared to those with higher estradiol, women with lower estradiol, and those using hormonal contraceptives (chronically suppressed estradiol) displayed higher speech-elicited skin conductance yet reported no differences in subjective anxiety or affect. Conversely, irrespective of estradiol status, compared to those with low self-reported social anxiety, participants with higher social anxiety exhibited greater subjective anxiety and affect, yet no differences in skin conductance. These results demonstrate that the relationship between estradiol and physiological fear responses extends to psychosocial tasks. However, the dissociations between physiological and subjective measures highlight the need to consider the relevance of different response outputs so that the potential impact of estradiol on the treatment of anxiety disorders can be better understood.

Postnatal stress is associated with impaired fear conditioning and extinction, and heightened hippocampal fibroblast growth factor 2, in mother rats

Rats exposed to early-life maternal separation (MS) exhibit later alterations in fear conditioning and impairments in fear extinction. As MS creates long-lasting anxiety in the mother, the present study assessed the influence of MS on fear conditioning and extinction in mother rats. It also examined whether estrous cycle effects on extinction, which are robust in nulliparous rats, but abolished in primiparous rats, re-emerge after MS. Following parturition, pups were removed from their mothers for 3 h daily from postpartum day 2-14 (MS), or remained housed with their mothers (standard reared condition, SR). Pups were weaned at postpartum day 24, and three months later, mothers received fear conditioning, extinction training, and test for extinction recall over three days. Extinction training took place during Proestrus (high estradiol and progesterone) or Metestrus (low estradiol and progesterone). Similar to past findings in non-stressed mothers, estrous cycle was not associated with conditioned fear expression (indexed by fear responses at the start of extinction training) or extinction recall in either MS or SR mothers. However, MS mothers exhibited weaker conditioned fear expression and impaired extinction recall, relative to SR mothers. Hippocampal fibroblast growth factor-2, a neurotrophin involved in stress regulation and fear expression, was elevated in MS relative to SR mothers. These results indicate that postnatal stress has long-lasting consequences for neural and behavioral systems involved in fear learning and inhibition without altering the involvement of ovarian hormones in these processes.

Estradiol-induced enhancement of fear extinction in female rats: The role of NMDA receptor activation

Converging cross-species evidence indicates that fear extinction (the laboratory basis of exposure therapy for anxiety disorders) in females is modulated by endogenous and exogenous estradiol. The mechanisms underlying estradiol's influences on fear extinction are largely undefined. However, one likely candidate is the NMDA-receptor (NMDAr), activation of which is necessary for estradiol-mediated enhancements in structural and functional neural plasticity, as well as extinction consolidation in males. Here, we demonstrate that systemic co-administration of the non-competitive NMDAr antagonist, MK801, blocked the enhancement of fear extinction by systemic estradiol in ovariectomized rats. In intact rats, MK801 during diestrus (rising estradiol) prevented the enhancement in extinction recall in rats that received extinction training during proestrus (peak estradiol). Systemic administration of the partial NMDAr agonist D-cycloserine (DCS) prior to extinction training facilitated extinction in ovariectomized rats, mimicking the effects of estradiol. In intact rats, DCS administered on the afternoon of proestrus and the morning of estrus (declining estradiol) facilitated extinction in rats that received extinction training during metestrus (low estradiol). Finally, DCS also facilitated extinction in ovariectomized rats when administered immediately after extinction training. Combined, these findings suggest that endogenous and exogenous estradiol enhance fear extinction via NMDAr-dependent mechanisms. Moreover, these findings raise the possibility that fear extinction deficits during periods of low endogenous estradiol levels can be reversed by increasing NMDAr activation via DCS administration, either well prior to, or immediately after, extinction training.

Estradiol moderates the relationship between state-trait anxiety and attentional bias to threat in women

Anxiety disorders are characterized by impaired fear extinction and heightened attentional allocation to threatening stimuli. The sex hormones estradiol and progesterone modulate fear extinction in female rats and women; whether these hormones are similarly related to attentional biases to threat has not been examined. In the present study 74 women (53 cycling, 21 using hormonal contraception), and a comparison group of 30 men, completed standard assessments of state-trait anxiety, as well symptoms of depression, anxiety and stress, followed by a computerized assessment of attentional bias, the dot-probe task. Women's endogenous estradiol and progesterone levels were ascertained by a blood sample. No differences in attentional bias were found dependent on sex or hormonal contraceptive use. Estradiol was the only variable measured that was independently positively correlated with attentional bias to threat. Regression analyses revealed a bi-directional relationship between state-trait anxiety, symptoms of anxiety and stress, and attentional bias that was moderated by estradiol, such that a positive relationship was observed amongst women with higher estradiol, and a negative relationship was observed amongst women with lower estradiol. Together, these results indicate that under conditions of anxiety and stress, women may attend to threat differently depending on endogenous estradiol levels, being avoidant when estradiol is lower, and vigilant when estradiol is higher. A more nuanced understanding of the role for attention in anxiety disorders amongst women may be developed by taking hormonal status into consideration.

Sex Hormones Are Associated With Rumination and Interact With Emotion Regulation Strategy Choice to Predict Negative Affect in Women Following a Sad Mood Induction

Women are particularly vulnerable to anxiety and depressive disorders. This greater vulnerability has been partly attributed to post-pubertal sex hormone fluctuations, estradiol and progesterone, as well as gender-specific tendencies to engage in maladaptive forms of emotion regulation, particularly rumination. To date, no research has investigated whether sex hormones are associated with emotion regulation in women. In the present study, 61 women participated in a sad mood induction task, involving the viewing of an emotive film. Negative affect was assessed immediately and following recovery, along with self-reported use of rumination, reappraisal, and suppression. Serum levels of estradiol and progesterone were assessed through a blood sample taken at the end of the experiment. Regression analyses were used to examine the relationship between serum hormones and self-reported emotional regulation strategy use, and between serum hormones and the impact of these strategies on negative affect. Estradiol levels positively predicted rumination, but not suppression or reappraisal use. Moreover, estradiol and progesterone interacted with emotion regulation strategies to predict negative affect following the sad mood induction. Reappraisal was associated with greater negative affect only in women with high estradiol, and in women with high progesterone. Conversely, rumination was associated with greater negative affect only in women with low estradiol. Together, these results suggest that sex hormone concentration may be an endogenous contextual factor that is associated with the selection and consequences of emotion regulation strategies in women.

Effects of d-cycloserine on individual differences in relapse of fear

The major weakness of psychological and pharmacological interventions for anxiety disorders is that the fear often returns. We examined whether DCS, which has attracted considerable attention as a potential pharmacological adjunct to therapy, reduces relapse, and whether individual differences in the rate of extinction modulates its effectiveness in reducing relapse. Experimentally-naïve adult male rats received pairings of a white noise CS with a shock US, extinction to a criterion immediately followed by an injection of DCS or Saline, and then were tested for relapse of fear (renewal, spontaneous recovery, or reinstatement; in four separate experiments). The number of blocks to reach criteria in extinction was used to classify animals as "Fast" or "Slow" Extinguishers. We consistently found that while DCS reduced relapse in Fast Extinguishers, it had minimal effects on relapse in Slow Extinguishers. Importantly, the differences in the effect of DCS on Fast and Slow Extinguishers was not due to Fast Extinguishers being less susceptible to relapse as animals in both groups exhibited similar amounts of relapse when injected with saline. Relapse, of all three types tested, was consistently reduced by DCS, but only in the Fast Extinguishers. Such findings contribute to a growing literature identifying factors that could influence the efficacy of pharmacological adjuncts to exposure therapy. These results have important implications for the development of personalized treatment approaches, which recognize, and are tailored to, individual differences.

Effects of systemic estradiol on fear extinction in female rats are dependent on interactions between dose, estrous phase, and endogenous estradiol levels

Administering estradiol to females during periods of low endogenous estradiol enhances their ability to extinguish fear, the laboratory basis of exposure therapy for anxiety disorders. It has therefore been proposed that estradiol could be a useful adjunct to enhance exposure therapy outcomes. The present study aimed to clarify the boundary conditions under which estradiol could be used for this purpose, by assessing whether the impact of estradiol, administered systemically prior to extinction training, differs depending on dose and estrous phase in adult female rats. Results demonstrated that in rats extinguished during metestrus (naturally low estradiol), a low dose of estradiol reduced freezing during extinction training and augmented extinction recall the following day, whereas a high dose of estradiol had no effect on either extinction training or recall. In rats extinguished during proestrus (naturally high estradiol), a high dose of estradiol impaired extinction recall, whereas a low dose of estradiol had no effect, or impairing effects, on extinction recall in different experiments. A subsequent analysis revealed that estradiol-treated proestrus rats that exhibited impaired extinction recall had significantly higher pre-treatment serum estradiol levels than those that exhibited good extinction recall. Together, these results indicate that systemically administered estradiol interacts with endogenous estradiol to produce an inverted U shaped dose effect on fear extinction, where low and high estradiol levels lead to poor extinction recall, and moderate estradiol levels lead to good extinction recall. These results highlight potential limitations to the use of estradiol as an adjunct to exposure therapy in clinical settings.

Fibroblast Growth Factor-2: A Promising Biomarker for Anxiety and Trauma Disorders

Anxiety and trauma disorders are a significant source of global burden. Although it is clear that there is great heterogeneity in humans' response to trauma and stress, most research on fear and anxiety has focused on the "average" animal. Increased understanding of the sources of individual differences in fear reactions may lead to more refined means of predicting who is at risk for the development of anxiety disorders so that early preventative interventions can be implemented. This commentary highlights recent cross-species work (in rats and humans) indicating that the neurotrophin fibroblast growth factor-2 (FGF2) holds promise as a potential biomarker for anxiety disorder vulnerability. Both central (hippocampal) and peripheral (serum and saliva) markers of FGF2 correlate negatively with fear expression after an aversive conditioning experience. Here, 2 broad accounts of the potential mechanism of vulnerability captured by measures of FGF2 are outlined. In particular, it is suggested that basal differences in FGF2 (across different tissue types) may provide a general index of one's regenerative capacity; alternatively, differences in FGF2 reactivity (in specific tissue types) may be indicative of one's coping capacity in response to stress.

Individual differences in fear extinction and anxiety-like behavior

There is growing appreciation for the substantial individual differences in the acquisition and inhibition of aversive associations, and the insights this might give into identifying individuals particularly vulnerable to stress and psychopathology. We examined whether animals that differed in rate of extinction (i.e., Fast versus Slow) were different in their response to an acute stress in adulthood or following a chronic stress that occurred either early or later in life. We found that Slow Extinguishers had significantly poorer extinction retention than Fast Extinguishers, but an acute stressor did not differentially affect anxiety-like behavior in the two groups. Further, while exposure to chronic stress in adulthood did not impact on the extinction phenotypes or anxiety-like behavior, exposure to chronic stress early in life affected both extinction retention and anxiety-like behavior. These findings have implications for the development of a more nuanced approach to identifying those most at risk of anxiety disorders.

Why are women so vulnerable to anxiety, trauma-related and stress-related disorders? The potential role of sex hormones

Increased prevalence, severity, and burden of anxiety, trauma-related and stress-related disorders in women compared with men has been well documented. Evidence from a variety of fields has emerged suggesting that sex hormones, particularly oestradiol and progesterone, play a significant part in generation of these sex differences. In this Series paper, we aim to integrate the literature reporting on the effects of sex hormones on biological, behavioural, and cognitive pathways, to propose two broad mechanisms by which oestradiol and progesterone influence sex differences in anxiety disorders: augmentation of vulnerability factors associated with anxiety disorder development; and facilitation of the maintenance of anxious symptoms post-development. The implications for future research, along with novel approaches to psychological and pharmacological treatment of anxiety disorders, are also considered.

Estradiol is associated with altered cognitive and physiological responses during fear conditioning and extinction in healthy and spider phobic women

The first-line psychological treatment for anxiety disorders is exposure therapy, which can be modeled in the laboratory using fear extinction. In healthy women, estradiol levels predict return of fear following extinction, whereas low levels are associated with greater return of fear. Investigating whether estradiol is similarly associated with extinction in clinically anxious women may provide insight to mechanisms underlying symptom relapse following exposure therapy. In the present study, women with spider phobia and healthy women participated in a 2-day fear conditioning and extinction procedure during a period of high or low estradiol levels. Skin conductance responses, shock expectancy, and valence ratings were measured throughout. Women exhibited comparable decreases in physiological arousal from conditioning to the end of extinction training on Day 1. However, compared to women with high estradiol, and irrespective of clinical status, women with low estradiol exhibited significant return of physiological arousal at extinction recall on Day 2, despite accurate ratings regarding the likelihood of shock. Low estradiol women also reported heightened threat expectancy and physiological responding during presentation of safety cues. These results may point to novel means of enhancing exposure therapy in women by timing treatment delivery during periods of higher estradiol levels. (PsycINFO Database Record

Mothers do it differently: reproductive experience alters fear extinction in female rats and women

Fear extinction is the laboratory basis of exposure therapy for anxiety disorders. Recent findings have revealed that estradiol is necessary to the consolidation of extinction memories in females. These findings are based on studies conducted using virgin rats and young women whose reproductive history is unknown. We hypothesized that motherhood, which results in extensive endocrinological, neurobiological and behavioral changes, may lead to alterations in fear extinction in females. We used a cross-species translational approach to investigate the impact of reproductive experience on fear extinction and fear relapse in female rats (n=116) and women (n=64). Although freezing during extinction recall was associated with estrous cycle phase during extinction training in virgin rats, this association was mitigated in age-matched reproductively experienced rats, even when fear extinction occurred 3 months after pups had been weaned, and even though reproductively experienced rats exhibited attenuated serum estradiol levels. In addition, although serum estradiol levels predicted extinction recall in human women with no prior reproductive experience, no such association was found in women with children. Finally, although virgin rats displayed both renewal and reinstatement after fear extinction, these common relapse phenomena were absent in rats with reproductive experience. Together, these findings suggest that reproductive experience alters the endocrine and behavioral features of fear extinction in females long after the hormonal surges of pregnancy and lactation have diminished. These results highlight the need to incorporate both hormonal and reproductive status as important factors in current models of fear extinction in females.

A Case Series of Laparoscopic Duodenojejunostomy for the Treatment of Pediatric Superior Mesenteric Artery Syndrome

Superior mesenteric artery syndrome (SMAS) is a rare, debilitating clinical condition caused by compression of the third portion of the duodenum by the superior mesenteric artery. Common symptoms include intermittent postprandial abdominal pain, nausea, weight loss, and bilious vomiting. Here we present a case series of three patients with SMAS who were treated with laparoscopic duodenojejunostomy. Patients were females between 12-17 years old. All patients underwent a successful laparoscopic duodenojejunostomy after diagnosis. Mean time to feedings after surgery was 4.00±1.15 days (mean ± SD) and length of stay was 8.6±2.7 days. SMAS remains a complex disease to diagnose and treat. Here we demonstrate that laparoscopic treatment of SMAS is a safe surgical treatment option, and is associated with earlier initiation of enteral feeds and a shorter hospital stay after surgery when compared to medical treatment. This is a safe, effective, and relatively simple procedure for the experienced minimally invasive surgeon [1].

Estradiol and Progesterone have Opposing Roles in the Regulation of Fear Extinction in Female Rats

Fear extinction, the laboratory basis of exposure therapy for anxiety disorders, fluctuates across the female rat estrous cycle, where extinction is enhanced during proestrus (high estradiol and progesterone), and impaired during metestrus (low estradiol and progesterone). During the estrous cycle increasing levels of estradiol precede and then overlap with increased levels of progesterone. We sought to isolate the impact of these hormonal changes on fear extinction by systematically treating ovariectomized female rats with estradiol alone, or in combination with progesterone. We found that estradiol alone facilitated extinction recall, whereas the effects of progesterone on estradiol-treated rats were biphasic and dependent on the time interval between progesterone administration and extinction training. Progesterone potentiated estradiol's facilitation of extinction recall when extinction training occurred 6 h after progesterone administration. However, progesterone abolished estradiol's facilitation of extinction recall when extinction training occurred 24 h after progesterone administration. Furthermore, in naturally cycling rats, blocking progesterone receptor activation during proestrus (when progesterone levels peak) prevented the impairment in extinction recall in rats extinguished during metestrus. These results suggest that in naturally cycling females whereas cyclical increases in estradiol facilitate fear extinction, cyclical increases in progesterone may lead to fear extinction impairments. As extinction training took place after the hormonal treatments had been metabolized, we propose that genomic mechanisms may at least partly mediate the impact of cyclic fluctuations in sex hormones on fear extinction.

Individual differences in the expression of conditioned fear are associated with endogenous fibroblast growth factor 2

These experiments examined the relationship between the neurotrophic factor fibroblast growth factor 2 (FGF2) and individual differences in the expression of conditioned fear. Experiments 1 and 2 demonstrated that rats naturally expressing low levels of contextual or cued fear have higher levels of hippocampal FGF2 relative to rats that express high levels of conditioned fear and nonconditioned rats. Experiment 3 demonstrated that hippocampal FGF2 is not increased in rats that exhibit pharmacological-induced amnesia of conditioned fear. Together, these experiments provide evidence that FGF2 may be an endogenous regulator of fear responses to conditioned stimuli.

Teens that fear screams: A comparison of fear conditioning, extinction, and reinstatement in adolescents and adults

This study investigated differences between adolescents and adults on fear conditioning, extinction, and reinstatement (i.e., the recovery of conditioned fear following re-exposure to the unconditioned stimulus [US] post-extinction). Participants underwent differential conditioning (i.e., the Screaming Lady) where one neutral face (CS+) was followed by the same face expressing fear and a loud scream (US) while another neutral face (CS-) remained neutral. Extinction involved non-reinforced presentations of both CSs, after which participants were reinstated (2xUSs) or not. On two self-report measures, both ages showed conditioning, good extinction learning and retention, and reinstatement-induced relapse. However, only adolescents showed conditioning, extinction, and reinstatement on the eye tracking measure; relapse on this measure could not be assessed in adults given they did not show initial conditioning. Lastly, higher levels of depression predicted stronger conditioning and weaker extinction in adolescents only. These findings are discussed in terms of their implications for adolescent anxiety disorders.

Inhibition of estradiol synthesis impairs fear extinction in male rats

Emerging research has demonstrated that the sex hormone estradiol regulates fear extinction in female rodents and women. Estradiol may also regulate fear extinction in males, given its role in synaptic plasticity in both sexes. Here we report that inhibition of estradiol synthesis during extinction training, via the aromatase inhibitor fadrozole, significantly impairs extinction recall in male rats. This deficit in extinction recall is not due to state-dependent memory formation and is completely abolished by coadministration of estradiol. Our data suggest that estradiol may be just as important in the regulation of fear extinction in males as it is in females.

Blockade of estrogen by hormonal contraceptives impairs fear extinction in female rats and women

BACKGROUND

Fear extinction is a laboratory model of fear inhibition and is the basis of exposure therapy for anxiety disorders. Emerging evidence from naturally cycling female rodents and women indicates that estrogens are necessary to the consolidation of fear extinction. Hormonal contraceptives (HCs) inhibit estrogen production; yet, their effects on fear extinction are unknown.

METHODS

We used a cross-species translational approach to investigate the impact of HCs and estradiol supplementation on fear extinction in healthy women (n=76) and female rats (n = 140).

RESULTS

Women using HCs exhibited significantly poorer extinction recall compared with naturally cycling women. The extinction impairment was also apparent in HC-treated female rats and was associated with reduced serum estradiol levels. The impairment could be rescued in HC-treated rats either by terminating HC treatment after fear learning or by systemic injection of estrogen-receptor agonists before fear extinction, all of which restored serum estradiol levels. Finally, a single administration of estradiol to naturally cycling women significantly enhanced their ability to recall extinction memories.

CONCLUSIONS

Together, these findings suggest that HCs may impact women's ability to inhibit fear but that this impairment is not permanent and could potentially be alleviated with estrogen treatment.

From resilience to vulnerability: mechanistic insights into the effects of stress on transitions in critical period plasticity

While early experiences are proposed to be important for the emergence of anxiety and other mental health problems, there is little empirical research examining the impact of such experiences on the development of emotional learning. Of the research that has been performed in this area, however, a complex picture has emerged in which the maturation of emotion circuits is influenced by the early experiences of the animal. For example, under typical laboratory rearing conditions infant rats rapidly forget learned fear associations (infantile amnesia) and express a form of extinction learning which is relapse-resistant (i.e., extinction in infant rats may be due to fear erasure). In contrast, adult rats exhibit very long-lasting memories of past learned fear associations, and express a form of extinction learning that is relapse-prone (i.e., the fear returns in a number of situations). However, when rats are reared under stressful conditions then they exhibit adult-like fear retention and extinction behaviors at an earlier stage of development (i.e., good retention of learned fear and relapse-prone extinction learning). In other words, under typical rearing conditions infant rats appear to be protected from exhibiting anxiety whereas after adverse rearing fear learning appears to make those infants more vulnerable to the later development of anxiety. While the effects of different experiences on infant rats' fear retention and extinction are becoming better documented, the mechanisms which mediate the early transition seen following stress remain unclear. Here we suggest that rearing stress may lead to an early maturation of the molecular and cellular signals shown to be involved in the closure of critical period plasticity in sensory modalities (e.g., maturation of GABAergic neurons, development of perineuronal nets), and speculate that these signals could be manipulated in adulthood to reopen infant forms of emotional learning (i.e., those that favor resilience).