Psychobiology of cumulative trauma: hair cortisol as a risk marker for stress exposure in women

Childhood trauma (CT) is associated with long-lasting alterations of the hypothalamic-pituitary-adrenal (HPA) axis and elevated risk for stress exposure in adulthood. Although HPA alterations are present in the early aftermath of trauma, it remains unclear how initial HPA activity is associated with subsequent stress exposure and whether CT exposure influences the strength and direction of this association. The present study examined prospective associations between hair cortisol content (HCC) and stress exposure from baseline to 3-month follow-up in young adult women with recent (i.e. past 3 months) exposure to interpersonal violence (IPV; i.e. physical or sexual assault) and non-traumatized controls. History of significant CT abuse or neglect was determined based on clinical cutoffs for a self-report CT measure: 12 women had abuse or neglect and recent IPV exposure (CT + IPV); 7 women had abuse or neglect but no IPV exposure (CT); 15 women had no history of trauma (NTC). HCC was computed for 3 cm sections reflecting cortisol secretion during the 3 months preceding the baseline assessment. The interaction of cumulative trauma and HCC predicted stress exposure over 3-month follow-up, controlling for baseline stress exposure and depressive symptoms. Simple slopes analyses revealed that lower baseline HCC predicted greater stress exposure in the CT + IPV group compared to the CT group; HCC was not associated with stress exposure in the NTC group. The present findings highlight the potential utility of HCC as a predictor of stress exposure for women with a history of childhood abuse or neglect, particularly in the context of recent IPV. Lay summary Adults with a history of CT show long-lasting alterations in major stress response systems, including the HPA axis. They are also more likely to experience stressful life events in adulthood. However, it is not clear how altered HPA activity influences risk for stress exposure and whether CT affects their relationship. The results from this study show that lower HPA activity (measured with hair cortisol) predicted greater stress exposure in women with CT - particularly for women who also experienced recent incidents involving physical or sexual assault.

Sigh rate during emotional transitions: More evidence for a sigh of relief

Evidence suggests that sighs regulate stress and emotions, e.g. by facilitating relief. This study aimed to investigate sigh rates during relief. In addition, links between sighs, anxiety sensitivity and HPA-axis activity were explored. Healthy volunteers (N=29) were presented cues predicting the valence of subsequent stimuli. By sequencing cues that predicted pleasant or unpleasant stimuli with or without certainty, transitions to certain pleasantness (relief) or to certain unpleasantness (control) were created and compared to no transitions. Salivary cortisol, anxiety sensitivity and respiration were measured. Sigh frequency was significantly higher during relief than during control transitions and no transition states, and higher during control transitions than during no transition states. Sigh frequency increased with steeper cortisol declines for high anxiety sensitive persons. Results confirm a relationship between sighs and relief. In addition, results suggest that sigh frequency is importantly related to HPA-axis activity, particularly in high anxiety sensitive persons.

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

OBJECTIVE

No simple way to augment fear extinction has been established. Cortisol has shown to enhance memory extinction and preliminary evidence suggest that extinction learning maybe more successful in the morning when cortisol is high. The aim was to determine whether exposure sessions conducted earlier in the day are associated with superior therapeutic gains in extinction-based psychotherapy. We also examined the role of cortisol levels as a mediator between time of day and therapeutic gains.

METHOD

Participants were 24 individuals meeting DSM-IV criteria for panic disorder with agoraphobia. Participants received 3 weekly in-vivo exposure sessions, yielding 72 total sessions for analysis of time of day effects. Session start times were evenly distributed across the day. The outcome measures were reductions in panic symptom severity (avoidance behaviors, threat misappraisal, perceived control, and panic disorder symptom severity).

RESULTS

Sessions starting earlier in the day were associated with superior therapeutic gains by the next therapy session. Earlier sessions were also associated with higher pre-exposure cortisol levels, which in turn were related to greater clinical improvement by the next session. Cortisol thus was found to mediate the effect of time of day on subsequent outcome, providing a link between earlier exposure sessions and greater clinical improvement.

CONCLUSION

The data suggest that early-day extinction-based therapy sessions yield better outcomes than later-day sessions, partly due to the enhancing effect of higher cortisol levels.

Cortisol, heart rate, and blood pressure as early markers of PTSD risk: A systematic review and meta-analysis

Individuals with posttraumatic stress disorder (PTSD) typically exhibit altered hypothalamic-pituitary-adrenal (HPA) function and sympathetic nervous system (SNS) activity. The goals of this study were to determine whether HPA and SNS alterations in the immediate aftermath of trauma predict subsequent PTSD symptom development and whether inconsistencies observed between studies can be explained by key demographic and methodological factors. This work informs secondary prevention of PTSD by identifying subgroups of trauma survivors at risk for PTSD. This meta-analysis (26 studies, N=5186 individuals) revealed that higher heart rate measured soon after trauma exposure was associated with higher PTSD symptoms subsequently (r=0.13). Neither cortisol (r=-0.07) nor blood pressure (diastolic: r=-0.01; systolic: r=0.02) were associated with PTSD symptoms which may be influenced by methodological limitations. Associations between risk markers (heart rate, cortisol, systolic blood pressure) and PTSD symptoms were in the positive direction for younger samples and negative direction for older samples. These findings extend developmental traumatology models of PTSD by revealing an age-related shift in the presentation of early risk markers. More work will be needed to identify risk markers and pathways to PTSD while addressing methodological limitations in order to shape and target preventive interventions.

PTSD SYMPTOMS ACROSS PREGNANCY AND EARLY POSTPARTUM AMONG WOMEN WITH LIFETIME PTSD DIAGNOSIS

BACKGROUND

Little is known about trajectories of PTSD symptoms across the peripartum period in women with trauma histories, specifically those who met lifetime PTSD diagnoses prior to pregnancy. The present study seeks to identify factors that influence PTSD symptom load across pregnancy and early postpartum, and study its impact on postpartum adaptation.

METHOD

The current study is a secondary analysis on pregnant women with a Lifetime PTSD diagnosis (N = 319) derived from a larger community sample who were interviewed twice across pregnancy (28 and 35 weeks) and again at 6 weeks postpartum, assessing socioeconomic risks, mental health, past and ongoing trauma exposure, and adaptation to postpartum.

RESULTS

Using trajectory analysis, first we examined the natural course of PTSD symptoms based on patterns across peripartum, and found four distinct trajectory groups. Second, we explored factors (demographic, historical, and gestational) that shape the PTSD symptom trajectories, and examined the impact of trajectory membership on maternal postpartum adaptation. We found that child abuse history, demographic risk, and lifetime PTSD symptom count increased pregnancy-onset PTSD risk, whereas gestational PTSD symptom trajectory was best predicted by interim trauma and labor anxiety. Women with the greatest PTSD symptom rise during pregnancy were most likely to suffer postpartum depression and reported greatest bonding impairment with their infants at 6 weeks postpartum.

CONCLUSIONS

Screening for modifiable risks (interpersonal trauma exposure and labor anxiety) and /or PTSD symptom load during pregnancy appears critical to promote maternal wellbeing.

Penn State Worry Questionnaire - 10: A new tool for measurement-based care

The Penn State Worry Questionnaire - Past Week (PSWQ-PW) is an adaptation of the widely used Penn State Worry Questionnaire, measuring pathological worry weekly. However, it contains problematic negatively worded items and has not been validated in a large sample yet. To meet the needs of measurement-based care (MBC), we developed a shortened version (PSWQ-10) based on the PSWQ-PW, retaining only positively worded items, and examined its psychometric properties and clinical utility. Patients with Generalized Anxiety Disorder (GAD), Major Depressive Disorder (MDD), and other anxiety disorders completed the PSWQ-10 and other instruments during routine evaluation in an academic anxiety clinic. A second cohort from a perinatal clinic was evaluated similarly. The PSWQ-10 displayed excellent internal consistency, convergent and discriminant validity, and criterion group validity. Patients with GAD scored significantly higher than those with other anxiety disorders but did not differ from those with MDD. The PSWQ-10 showed sensitivity to change over time and demonstrated excellent psychometric properties in the perinatal population. The PSWQ-10 is a reliable, valid, efficient, and straightforward worry-focused instrument that can be readily used in MBC and help clinicians objectively measure worry as a treatment outcome in broad clinical populations.

Does Worrying Mean Caring Too Much? Interpersonal Prototypicality of Dimensional Worry Controlling for Social Anxiety and Depressive Symptoms

Worry, social anxiety, and depressive symptoms are dimensions that have each been linked to heterogeneous problems in interpersonal functioning. However, the relationships between these symptoms and interpersonal difficulties remain unclear given that most studies have examined diagnostic categories, not accounted for symptoms' shared variability due to general distress, and investigated only interpersonal problems (neglecting interpersonal traits, interpersonal goals, social behavior in daily life, and reports of significant others). To address these issues, students (Study 1; N=282) endorsed symptoms and interpersonal circumplex measures of traits and problems, as well as event-contingent social behaviors during one week of naturalistic daily interactions (N=184; 7,036 records). Additionally, depressed and anxious patients (N=47) reported symptoms and interpersonal goals in a dyadic relationship, and significant others rated patients' interpersonal goals and impact (Study 2). We derived hypotheses about prototypical interpersonal features from theories about the functions of particular symptoms and social behaviors. As expected, worry was uniquely associated with prototypically affiliative tendencies across all self-report measures in both samples, but predicted impacting significant others in unaffiliative ways. As also hypothesized, social anxiety was uniquely and prototypically associated with low dominance across measures, and general distress was associated with cold-submissive tendencies. Findings for depressive symptoms provided less consistent evidence for unique prototypical interpersonal features. Overall, results suggest the importance of multimethod assessment and accounting for general distress in interpersonal models of worry, social anxiety, and depressive symptoms.

Cortisol Awakening Response and Internalizing Symptoms Across Childhood: Exploring the Role of Age and Externalizing Symptoms

Efforts to identify biological correlates of internalizing symptoms in childhood have involved examinations of HPA-axis functioning, namely Cortisol Awakening Response (CAR). However, research has not assessed the relationship between CAR and internalizing problems among children younger than 8 years. Findings with older samples have been somewhat equivocal, perhaps due to high rates of co-occurring externalizing symptoms during childhood and/or due to age-related differences. This cross-sectional study examined CAR in an at-risk sample of children aged 22 months to 8 years at various levels of risk for internalizing symptoms. Internalizing symptoms were associated with blunted CAR, but only after controlling for externalizing problems. The relationship between CAR and internalizing symptoms disappeared with age. Results demonstrate that a negative association between CAR and internalizing exists during early childhood and illustrate the importance of accounting for comorbid externalizing disorders and developmental stage when assessing the HPA-internalizing link.

Longitudinal examination of infant baseline and reactivity cortisol from ages 7 to 16 months

This study characterized the longitudinal evolution of HPA axis functioning from 7 to 16 months of age and identified individual and environmental factors that shape changes in HPA axis functioning over time. Participants were 167 mother-infant dyads drawn from a larger longitudinal study, recruited based on maternal history of being maltreated during childhood. Salivary cortisol levels were assessed before and after age-appropriate psychosocial stressors when infants were 7 and 16 months old. Maternal observed parenting and maternal reports of infant and environmental characteristics were obtained at 7 months and evaluated as predictors of changes in infant baseline cortisol and reactivity from 7 to 16 months. Results revealed that infants did not show a cortisol response at 7 months, but reactivity to psychosocial stress emerged by 16 months. Individual differences in cortisol baseline and reactivity levels over time were related to infant sex and maternal overcontrolling behaviors, underscoring the malleable and socially informed nature of early HPA axis functioning. Findings can inform prevention and intervention efforts to promote healthy stress regulation during infancy.

Alterations in cognitive flexibility in a rat model of post-traumatic stress disorder

Exposure to stressful or traumatic events is associated with increased vulnerability to post-traumatic stress disorder (PTSD). This vulnerability may be partly mediated by effects of stress on the prefrontal cortex (PFC) and associated circuitry. The PFC mediates critical cognitive functions, including cognitive flexibility, which reflects an organism's ability to adaptively alter behavior in light of changing contingencies. Prior work suggests that chronic or acute stress exerts complex effects on different forms of cognitive flexibility, via actions on the PFC. Similarly, PFC dysfunction is reported in PTSD, as are executive function deficits. Animal models that permit study of the effects of stress/trauma on cognitive flexibility may be useful in illuminating ways in which stress-linked cognitive changes contribute to PTSD. Here, we examined the behavioral effects of a rodent model of PTSD - single prolonged stress (SPS) - on performance of two forms of cognitive flexibility: reversal learning and strategy set-shifting. SPS did not impair acquisition of either a response or visual-cue discrimination but did cause slight impairments in the retrieval of the visual-cue rule. During response discrimination reversal, SPS rats made more perseverative errors. In comparison, during set-shifting from the visual-cue to response discrimination, SPS rats did not show enhanced perseveration, but did display increased never-reinforced errors, indicative of impairment in selecting a novel strategy. These data demonstrate that SPS leads to a complex and intriguing pattern of deficits in flexible responding and suggest that impairments in executive functioning associated with PTSD could, in part, be a neuro-cognitive consequence of trauma exposure.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Brain Mechanisms of Social Threat Effects on Working Memory

Social threat can have adverse effects on cognitive performance, but the brain mechanisms underlying its effects are poorly understood. We investigated the effects of social evaluative threat on working memory (WM), a core component of many important cognitive capabilities. Social threat impaired WM performance during an N-back task and produced widespread reductions in activation in lateral prefrontal cortex and intraparietal sulcus (IPS), among other regions. In addition, activity in frontal and parietal regions predicted WM performance, and mediation analyses identified regions in the bilateral IPS that mediated the performance-impairing effects of social threat. Social threat also decreased connectivity between the IPS and dorsolateral prefrontal cortex, while increasing connectivity between the IPS and the ventromedial prefrontal cortex, a region strongly implicated in the generation of autonomic and emotional responses. Finally, cortisol response to the stressor did not mediate WM impairment but was rather associated with protective effects. These results provide a basis for understanding interactions between social and cognitive processes at a neural systems level.

Effortful control and context interact in shaping neuroendocrine stress responses during childhood

Trait and contextual factors can shape individual and group differences in hypothalamic-pituitary-adrenal (HPA) response to stress; but the ways in which these factors may interact with each other to modulate stress activity have rarely been examined. Here, we investigated whether the association between a temperamental self-regulatory trait - Effortful Control (EC) - and HPA axis stress response is moderated by type of laboratory stress in sixty-five children (35 boys). EC was measured at ages 3 and 6 using age-appropriate laboratory batteries as well as mother reports. HPA axis responses were measured at age 7 by randomly assigning children to one of two laboratory stress tasks (frustration vs. fear). Results indicated that EC interacted with stress context in predicting cortisol response. Specifically, lower EC was associated with greater cortisol response (steeper reactivity slopes) in the context of a frustration stressor but this was reversed in a fear context where lower EC was associated with flatter, more gradual activation. It is likely that different components of EC, such as emotion regulation and attention, differentially interact with the stress context. These types of effects and interactions need to be more thoroughly understood in order to meaningfully interpret cortisol reactivity data and better characterize the role of the HPA axis in human psychopathology.

Modeling neuroendocrine stress reactivity in salivary cortisol: adjusting for peak latency variability

In this report, we present growth curve modeling (GCM) with landmark registration as an alternative statistical approach for the analysis of time series cortisol data. This approach addresses an often-ignored but critical source of variability in salivary cortisol analyses: individual and group differences in the time latency of post-stress peak concentrations. It allows for the simultaneous examination of cortisol changes before and after the peak while controlling for timing differences, and thus provides additional information that can help elucidate group differences in the underlying biological processes (e.g., intensity of response, regulatory capacity). We tested whether GCM with landmark registration is more sensitive than traditional statistical approaches (e.g., repeated measures ANOVA--rANOVA) in identifying sex differences in salivary cortisol responses to a psychosocial stressor (Trier Social Stress Test--TSST) in healthy adults (mean age 23). We used plasma ACTH measures as our "standard" and show that the new approach confirms in salivary cortisol the ACTH finding that males had longer peak latencies, higher post-stress peaks but a more intense post-peak decline. This finding would have been missed if only saliva cortisol was available and only more traditional analytic methods were used. This new approach may provide neuroendocrine researchers with a highly sensitive complementary tool to examine the dynamics of the cortisol response in a way that reduces risk of false negative findings when blood samples are not feasible.

The Persistence of Experience: Prior Attentional and Emotional State Affects Network Functioning in a Target Detection Task

Efficient, adaptive behavior relies on the ability to flexibly move between internally focused (IF) and externally focused (EF) attentional states. Despite evidence that IF cognitive processes such as event imagination comprise a significant amount of awake cognition, the consequences of internal absorption on the subsequent recruitment of brain networks during EF tasks are unknown. The present functional magnetic resonance imaging (fMRI) study employed a novel attentional state switching task. Subjects imagined positive and negative events (IF task) or performed a working memory task (EF task) before switching to a target detection (TD) task also requiring attention to external information, allowing for the investigation of neural functioning during external attention based on prior attentional state. There was a robust increase of activity in frontal, parietal, and temporal regions during TD when subjects were previously performing the EF compared with IF task, an effect that was most pronounced following negative IF. Additionally, dorsolateral prefrontal cortex was less negatively coupled with ventromedial prefrontal and posterior cingulate cortices during TD following IF compared with EF. These findings reveal the striking consequences for brain activity following immersion in an IF attentional state, which have strong implications for psychiatric disorders characterized by excessive internal focus.

Brief cognitive intervention can modulate neuroendocrine stress responses to the Trier Social Stress Test: buffering effects of a compassionate goal orientation

BACKGROUND

The hypothalamic-pituitary-adrenal (HPA) axis is a critical mediator linking stress to health. Understanding how to modulate its reactivity could potentially help reduce the detrimental health effects of HPA axis activation. Social evaluative threat is a potent activator of this system. Access to control and coping responses can reduce its reactivity to pharmacological activation. Compassionate or affiliative behaviors may also moderate stress reactivity. Impact of these moderators on social evaluative threat is unknown. Here, we tested the hypotheses that interventions to increase control, coping, or compassionate (versus competitive) goals could reduce HPA-axis response to social evaluative threat.

METHODS

Healthy participants (n=54) were exposed to social evaluative threat using the Trier Social Stress Test (TSST). They were randomly assigned to receive one of four different instructions prior to the stressor: Standard TSST instructions (SI), standard instructions with access to "control" (SI Control), or one of two cognitive interventions (CI) that (1) increased familiarity and helped participants prepare coping strategies (CI Coping), or (2) shifted goal orientation from self-promotion to helping others (CI Compassionate Goals). ACTH and cortisol were obtained before and after stress exposure via intravenous catheter.

RESULTS

Control alone had no effect. CI Compassionate Goals significantly reduced ACTH and cortisol responses to the TSST; CI Coping raised baseline levels. Compassionate Goals reduced hormonal responses without reducing subjective anxiety, stress or fear, while increasing expression of pro-social intentions and focus on helping others.

CONCLUSIONS

Brief intervention to shift focus from competitive self-promotion to a goal orientation of helping-others can reduce HPA-axis activation to a potent psychosocial stressor. This supports the potential for developing brief interventions as inoculation tools to reduce the impact of predictable stressors and lends support to growing evidence that compassion and altruistic goals can moderate the effects of stress.

DHEA enhances emotion regulation neurocircuits and modulates memory for emotional stimuli

Dehydroepiandrosterone (DHEA) is a neurosteroid with anxiolytic, antidepressant, and antiglucocorticoid properties. It is endogenously released in response to stress, and may reduce negative affect when administered exogenously. Although there have been multiple reports of DHEA's antidepressant and anxiolytic effects, no research to date has examined the neural pathways involved. In particular, brain imaging has not been used to link neurosteroid effects to emotion neurocircuitry. To investigate the brain basis of DHEA's impact on emotion modulation, patients were administered 400 mg of DHEA (N=14) or placebo (N=15) and underwent 3T fMRI while performing the shifted-attention emotion appraisal task (SEAT), a test of emotional processing and regulation. Compared with placebo, DHEA reduced activity in the amygdala and hippocampus, enhanced connectivity between the amygdala and hippocampus, and enhanced activity in the rACC. These activation changes were associated with reduced negative affect. DHEA reduced memory accuracy for emotional stimuli, and also reduced activity in regions associated with conjunctive memory encoding. These results demonstrate that DHEA reduces activity in regions associated with generation of negative emotion and enhances activity in regions linked to regulatory processes. Considering that activity in these regions is altered in mood and anxiety disorders, our results provide initial neuroimaging evidence that DHEA may be useful as a pharmacological intervention for these conditions and invite further investigation into the brain basis of neurosteroid emotion regulatory effects.

Exogenous glucocorticoids decrease subgenual cingulate activity evoked by sadness

The glucocorticoid hormone cortisol is known to have wide-ranging effects on a variety of physiological systems, including the morphology and physiology of the amygdala and hippocampus. Disruptions of cortisol regulation and signaling are also linked with psychiatric disorders involving emotional disturbances. Although there is much evidence to suggest a relationship between cortisol signaling and the brain physiology underlying emotion, few studies have attempted to test for direct effects of cortisol on the neurophysiology of emotion. We administered exogenous synthetic cortisol (hydrocortisone, HCT) using two different dosing regimens (25 mg/day over 4 days, 100 mg single dose), in a double-blind placebo-controlled functional magnetic resonance imaging (fMRI) study. During fMRI scanning, healthy subjects viewed images designed to induce happy, sad, and neutral emotional states. Subjective emotional reactions were collected for each experimental stimulus after fMRI scanning. Mood ratings were also collected throughout the 4 days of the study. Both dose regimens of HCT resulted in decreased subgenual cingulate activation during sadness conditions. The 25 mg/day regimen also resulted in higher arousal ratings of sad stimuli. No effects of HCT were observed on any mood ratings. Few reliable effects of HCT were observed on brain activity patterns or subjective emotional responses to stimuli that were not sad. The inhibitory effects of cortisol on sadness-induced subgenual cingulate activity may have critical relevance to the pathophysiology of major depression, as both subgenual hyperactivity and decreased sensitivity to cortisol signaling have been documented in patients with depression.

Psychological and environmental correlates of HPA axis functioning in parentally bereaved children: preliminary findings

This study examined bereaved children's HPA-axis functioning (cortisol awakening response; CAR) in relation to psychological distress, coping, and surviving parents' grief reactions. Participants included 38 children (20 girls) with recent parental loss (previous 6 months) and 28 of their surviving caregivers (23 women) who were assessed using self-report instruments and in-person, semistructured interviews. Interviews involved discussions about the child's thoughts and feelings related to the loss. Participants provided 3 saliva samples at home (awakening, 30 minutes later, and evening) over 3 successive days, beginning on the day following the interview. Results show a significant relation between dampening of the child's Day 1 CAR and more symptoms of anxiety (r = -.45), depression (r = -.40), posttraumatic stress (r = -.45), and maladaptive grief (r = -.43), as well as higher levels of avoidant coping (r = -.53). Higher levels of parental maladaptive grief were also associated (r = -.47) with a dampening of the child's Day 1 CAR. Our results raise the possibility that blunted CAR may be a result of accumulating allostatic load and/or a result of emotionally challenging events (discussions regarding the deceased) and their subsequent processing (or lack thereof) within the family, which may be particularly stressful for those bereaved children experiencing high levels of psychological distress, avoidant coping, and parental maladaptive grief.

Respiratory variability and sighing: a psychophysiological reset model

Whereas respiratory psychophysiological research has mainly studied respiratory time and volume, variability in these parameters has been largely disregarded, even though it may provide important information about respiratory regulation. The present paper reviews the literature on respiratory variability and elaborates on the importance of assessing various components of respiratory variability when studying the interrelationships between emotions and breathing. A model is proposed that predicts specific action tendencies related to emotions to disturb the balance between various respiratory variability components depending on valence by arousal and control dimensions. The central focus of the paper is sighing. The causes and consequences of sighing are reviewed and integrated in the proposed model in which sighing is hypothesized to function as a resetter in the regulation of both breathing and emotions, because it restores a balance in respiratory variability fractions and causes relief.

Cannabinoid facilitation of fear extinction memory recall in humans

A first-line approach to treat anxiety disorders is exposure-based therapy, which relies on extinction processes such as repeatedly exposing the patient to stimuli (conditioned stimuli; CS) associated with the traumatic, fear-related memory. However, a significant number of patients fail to maintain their gains, partly attributed to the fact that this inhibitory learning and its maintenance is temporary and conditioned fear responses can return. Animal studies have shown that activation of the cannabinoid system during extinction learning enhances fear extinction and its retention. Specifically, CB1 receptor agonists, such as Δ9-tetrahydrocannibinol (THC), can facilitate extinction recall by preventing recovery of extinguished fear in rats. However, this phenomenon has not been investigated in humans. We conducted a study using a randomized, double-blind, placebo-controlled, between-subjects design, coupling a standard Pavlovian fear extinction paradigm and simultaneous skin conductance response (SCR) recording with an acute pharmacological challenge with oral dronabinol (synthetic THC) or placebo (PBO) 2 h prior to extinction learning in 29 healthy adult volunteers (THC = 14; PBO = 15) and tested extinction retention 24 h after extinction learning. Compared to subjects that received PBO, subjects that received THC showed low SCR to a previously extinguished CS when extinction memory recall was tested 24 h after extinction learning, suggesting that THC prevented the recovery of fear. These results provide the first evidence that pharmacological enhancement of extinction learning is feasible in humans using cannabinoid system modulators, which may thus warrant further development and clinical testing. This article is part of a Special Issue entitled 'Cognitive Enhancers'.

Resting-state functional connectivity between fronto-parietal and default mode networks in obsessive-compulsive disorder

Background

Obsessive-compulsive disorder (OCD) is characterized by an excessive focus on upsetting or disturbing thoughts, feelings, and images that are internally-generated. Internally-focused thought processes are subserved by the “default mode network" (DMN), which has been found to be hyperactive in OCD during cognitive tasks. In healthy individuals, disengagement from internally-focused thought processes may rely on interactions between DMN and a fronto-parietal network (FPN) associated with external attention and task execution. Altered connectivity between FPN and DMN may contribute to the dysfunctional behavior and brain activity found in OCD.

Methods

The current study examined interactions between FPN and DMN during rest in 30 patients with OCD (17 unmedicated) and 32 control subjects (17 unmedicated). Timecourses from seven fronto-parietal seeds were correlated across the whole brain and compared between groups.

Results

OCD patients exhibited altered connectivity between FPN seeds (primarily anterior insula) and several regions of DMN including posterior cingulate cortex, medial frontal cortex, posterior inferior parietal lobule, and parahippocampus. These differences were driven largely by a reduction of negative correlations among patients compared to controls. Patients also showed greater positive connectivity between FPN and regions outside DMN, including thalamus, lateral frontal cortex, and somatosensory/motor regions.

Conclusions

OCD is associated with abnormal intrinsic functional connectivity between large-scale brain networks. Alteration of interactions between FPN and DMN at rest may contribute to aspects of the OCD phenotype, such as patients' inability to disengage from internally-generated scenarios and thoughts when performing everyday tasks requiring external attention.