Multimodal Categorical and Dimensional Approaches to Understanding Threat Conditioning and Its Extinction in Individuals With Anxiety Disorders

Cannabidiol in anxiety disorders: Current and future perspectives

Anxiety disorders are highly prevalent psychiatric disorders, characterized by a chronic course and often accompanied by comorbid symptoms that impair functionality and decrease quality of life. Despite advances in basic and clinical research in our understanding of these disorders, currently available pharmacological options are associated with limited clinical benefits and side effects that frequently lead to treatment discontinuation. Importantly, a significant number of patients do not achieve remission and live with lifelong residual symptoms that limit daily functioning. Since the 1970s, basic and clinical research on cannabidiol (CBD), a non-psychotomimetic compound found in the Cannabis sativa plant, has indicated relevant anxiolytic effects, garnering attention for its therapeutic potential as an option in anxiety disorder treatment. This chapter aims to review the history of these studies on the anxiolytic effects of CBD within the current understanding of anxiety disorders. It highlights the most compelling current evidence supporting its anxiolytic effects and explores future perspectives for its clinical use in anxiety disorders.

Anhedonia is associated with overgeneralization of conditioned fear during late adolescence and early adulthood

BACKGROUND

Pavlovian fear paradigms involve learning to associate cues with threat or safety. Aberrances in Pavlovian fear learning correlate with psychopathology, especially anxiety disorders. This study evaluated symptom dimensions of anxiety and depression in relation to Pavlovian fear acquisition and generalization.

METHODS

256 participants (70.31 % female) completed a Pavlovian fear acquisition and generalization paradigm at ages 18-19 and 21-22 years. Analyses focused on indices of learning (self-reported US expectancy, skin conductance). Multilevel models tested associations with orthogonal symptom dimensions (Anhedonia-Apprehension, Fears, General Distress) at each timepoint.

RESULTS

All dimensions were associated with weaker acquisition of US expectancies at each timepoint. Fears was associated with overgeneralization only at age 21-22. General Distress was associated with overgeneralization only at age 18-19. Anhedonia-Apprehension was associated with overgeneralization at ages 18-19 and 21-22.

CONCLUSIONS

Anhedonia-Apprehension disrupts Pavlovian fear acquisition and increases overgeneralization of fear. These effects may emerge during adolescence and remain into young adulthood. General Distress and Fears also contribute to overgeneralization of fear, but these effects may vary as prefrontal mechanisms of fear inhibition continue to develop during late adolescence. Targeting specific symptom dimensions, particularly Anhedonia-Apprehension, may decrease fear generalization and augment interventions built on Pavlovian principles, such as exposure therapy.

Impaired Cortico-Thalamo-Cerebellar Integration Across Schizophrenia, Bipolar II, and Attention Deficit Hyperactivity Disorder Patients Suggests Potential Neural Signatures for Psychiatric Illness

Understanding aberrant functional changes between brain regions has shown promise for characterizing and differentiating the symptoms associated with progressive psychiatric disorders. The functional integration between the thalamus and cerebellum significantly influences learning and memory in cognition. Observed in schizophrenic patients, dysfunction within the corticalthalamocerebellar (CTC) circuitry is linked to challenges in prioritizing, processing, coordinating, and responding to information. This study explored whether abnormal CTC functional network connectivity patterns are present across schizophrenia (SCHZ) patients, bipolar II disorder (BIPOL) patients, and ADHD patients by examining both task- and task-free conditions compared to healthy volunteers (HC). Leveraging fMRI data from 135 participants (39 HC, 27 SCHZ patients, 38 BIPOL patients, and 31 ADHD patients), we analyzed functional network connectivity (FNC) patterns across 115 cortical, thalamic, subcortical, and cerebellar regions of interest (ROIs). Guiding our investigation: First, do the brain regions of the CTC circuit exhibit distinct abnormal patterns at rest in SCHZ, ADHD, and BIPOL? Second, do working memory tasks in these patients engage common regions of the circuit in similar or unique patterns? Consistent with previous findings, our observations revealed FNC patterns constrained in the cerebellar, thalamic, striatal, hippocampal, medial prefrontal and insular cortices across all three psychiatric cohorts when compared to controls in both task and task-free conditions. Post hoc analysis suggested a predominance in schizophrenia and ADHD patients during rest, while the task condition demonstrated effects across all three disorders. Factor-by-covariance GLM MANOVA further specified regions associated with clinical symptoms and trait assessments. Our study provides evidence suggesting that dysfunctional CTC circuitry in both task-free and task-free conditions may be an important broader neural signature of psychiatric illness.

The effects of parental presence on amygdala and mPFC activation during fear conditioning: An exploratory study

Learning safe versus dangerous cues is crucial for survival. During development, parents can influence fear learning by buffering their children's stress response and increasing exploration of potentially aversive stimuli. Rodent findings suggest that these behavioral effects are mediated through parental presence modulation of the amygdala and medial prefrontal cortex (mPFC). Here, we investigated whether similar parental modulation of amygdala and mPFC during fear learning occurs in humans. Using a within-subjects design, behavioral (final N = 48, 6-17 years, mean = 11.61, SD = 2.84, 60% females/40% males) and neuroimaging data (final N = 39, 6-17 years, mean = 12.03, SD = 2.98, 59% females/41% males) were acquired during a classical fear conditioning task, which included a CS+ followed by an aversive noise (US; 75% reinforcement rate) and a CS-. Conditioning occurred once in physical contact with the participant's parent and once alone (order counterbalanced). Region of interest analyses examined the unconditioned stress response by BOLD activation to the US (vs. implicit baseline) and learning by activation to the CS+ (vs. CS-). Results showed that during US presentation, parental presence reduced the centromedial amygdala activity, suggesting buffering of the unconditioned stress response. In response to learned stimuli, parental presence reduced mPFC activity to the CS+ (relative to the CS-), although this result did not survive multiple comparisons' correction. These preliminary findings indicate that parents modulate amygdala and mPFC activity during exposure to unconditioned and conditioned fear stimuli, potentially providing insight into the neural mechanisms by which parents act as a social buffer during fear learning. RESEARCH HIGHLIGHTS: (1)This study used a within-participant experimental design to investigate how parental presence (vs. absence) affects youth's neural responses in a classical fear conditioning task. (2)Parental presence reduced the youth's centromedial amygdala activation to the unconditioned stimulus (US), suggesting parental buffering of the neural unconditioned response (UR). (3)Parental presence reduced the youth's mPFC activation to a conditioned threat cue (CS+) compared to a safety cue (CS-), suggesting possible parental modulation of fear learning.

Distributed neural representations of conditioned threat in the human brain

Detecting and responding to threat engages several neural nodes including the amygdala, hippocampus, insular cortex, and medial prefrontal cortices. Recent propositions call for the integration of more distributed neural nodes that process sensory and cognitive facets related to threat. Integrative, sensitive, and reproducible distributed neural decoders for the detection and response to threat and safety have yet to be established. We combine functional MRI data across varying threat conditioning and negative affect paradigms from 1465 participants with multivariate pattern analysis to investigate distributed neural representations of threat and safety. The trained decoders sensitively and specifically distinguish between threat and safety cues across multiple datasets. We further show that many neural nodes dynamically shift representations between threat and safety. Our results establish reproducible decoders that integrate neural circuits, merging the well-characterized 'threat circuit' with sensory and cognitive nodes, discriminating threat from safety regardless of experimental designs or data acquisition parameters.

Unconditioned response to a naturally aversive stimulus is associated with sensitized defensive responding and self-reported fearful traits in a PTSD sample

Unconditioned responding (UCR) to a naturally aversive stimulus is associated with defensive responding to a conditioned threat cue (CS+) and a conditioned safety cue (CS-) in trauma-exposed individuals during fear acquisition. However, the relationships of UCR with defensive responses during extinction training, posttraumatic stress disorder (PTSD) symptom severity, and fearful traits in trauma-exposed individuals are not known. In a sample of 100 trauma-exposed adults with a continuum of PTSD severity, we recorded startle responses and skin conductance responses (SCR) during fear acquisition and extinction training using a 140 psi, 250-ms air blast to the larynx as the unconditioned stimulus. We explored dimensional associations of two different measures of UCR (unconditioned startle and unconditioned SCR) with conditioned defensive responding to CS+ and CS-, conditioned fear (CS+ minus CS-), PTSD symptom severity, and a measure of fearful traits (composite of fear survey schedule, anxiety sensitivity index, and Connor-Davidson resilience scale). Unconditioned startle was positively associated with startle potentiation to the threat cue and the safety cue across both learning phases (CS+ Acquisition, CS- Acquisition, CS+ Extinction Training, CS- Extinction Training) and with fearful traits. Unconditioned SCR was positively associated with SCR to the CS+ and CS- and SCR difference score during Acquisition. Neither type of UCR was associated with PTSD symptom severity. Our findings suggest that UCR, particularly unconditioned startle to a naturally aversive stimulus, may inform research on biomarkers and treatment targets for symptoms of pervasive and persistent fear in trauma-exposed individuals.

Using unconditioned responses to predict fear acquisition, fear extinction learning, and extinction retention patterns: Sex hormone status matters

Following a traumatic event, fear dysregulation can increase the likelihood of developing post-traumatic stress disorder (PTSD). This psychopathology is twice as prevalent in women than in men. High physiological reactivity following trauma may be an early risk indicator for the development of PTSD. Elevated physiological reactivity and low estradiol levels have individually been associated with higher fear acquisition and/or lower extinction retention. Thus, sex hormone status may also modulate fear regulation abilities. However, it is unknown whether these two vulnerability factors interact to modulate fear learning and regulation. Using a fear conditioning and extinction protocol, we examined whether physiological reactivity to the aversive stimulus during fear acquisition training predicted fear responses during fear learning, extinction learning, and extinction retention. We verified whether these associations differed according to sex hormone status. Seventy-seven non-clinical participants were recruited including oral contraceptive users (n = 18), early follicular women (n = 20, [low estradiol]), mid-cycle women (n = 20, [high estradiol]), and men (n = 19). Participants underwent a three-day fear conditioning and extinction protocol (day 1: fear acquisition training; day 2: extinction training; day 3: retention test). Skin conductance responses were recorded. In early follicular women, physiological reactivity predicted conditioned and extinguished stimulus fear responses during all phases. For the remaining women, this effect was only present during fear learning and extinction learning. These findings highlight the importance of considering physiological reactivity and sex hormone status following a traumatic event. This knowledge could aid in the early identification of those at higher risk of developing PTSD.

Neural correlates of context-dependent extinction recall in social anxiety disorder: relevance of intrusions in response to aversive social experiences

BACKGROUND

There are phenomenological similarities between social anxiety disorder (SAD) and posttraumatic stress disorder, such as a provoking aversive event, posttraumatic stress symptoms (e.g. intrusions) in response to these events and deficient (context-dependent) fear conditioning processes. This study investigated the neural correlates of context-dependent extinction recall and fear renewal in SAD, specifically in patients with intrusions in response to an etiologically relevant aversive social event.

METHODS

During functional magnetic resonance imaging a two-day context-dependent fear conditioning paradigm was conducted in 54 patients with SAD and 54 healthy controls (HC). This included fear acquisition (context A) and extinction learning (context B) on one day, and extinction recall (context B) as well as fear renewal (contexts C and A) one day later. The main outcome measures were blood oxygen level-dependent responses in regions of interest and skin conductance responses.

RESULTS

Patients with SAD showed reduced differential conditioned amygdala activation during extinction recall in the safe extinction context and during fear renewal in the acquisition context compared to HC. Patients with clinically relevant intrusions moreover exhibited hypoactivation of the ventromedial prefrontal cortex (vmPFC) during extinction learning, extinction recall, and fear renewal in a novel context, while amygdala activation more strongly decreased during extinction learning and increased during fear renewal in the acquisition context compared with patients without intrusions.

CONCLUSIONS

Our study provides first evidence that intrusions in SAD are associated with similar deficits in context-dependent regulation of conditioned fear via the vmPFC as previously demonstrated in posttraumatic stress disorder.

Revisiting deficits in threat and safety appraisal in obsessive-compulsive disorder

Current behavioural treatment of obsessive-compulsive disorder (OCD) is informed by fear conditioning and involves iteratively re-evaluating previously threatening stimuli as safe. However, there is limited research investigating the neurobiological response to conditioning and reversal of threatening stimuli in individuals with OCD. A clinical sample of individuals with OCD (N = 45) and matched healthy controls (N = 45) underwent functional magnetic resonance imaging. While in the scanner, participants completed a well-validated fear reversal task and a resting-state scan. We found no evidence for group differences in task-evoked brain activation or functional connectivity in OCD. Multivariate analyses encompassing all participants in the clinical and control groups suggested that subjective appraisal of threatening and safe stimuli were associated with a larger difference in brain activity than the contribution of OCD symptoms. In particular, we observed a brain-behaviour continuum whereby heightened affective appraisal was related to increased bilateral insula activation during the task (r = 0.39, pFWE  = .001). These findings suggest that changes in conditioned threat-related processes may not be a core neurobiological feature of OCD and encourage further research on the role of subjective experience in fear conditioning.

Brain activation during fear extinction recall in unmedicated patients with obsessive-compulsive disorder

Specific brain activation patterns during fear conditioning and the recall of previously extinguished fear responses have been associated with obsessive-compulsive disorder (OCD). However, further replication studies are necessary. We measured skin-conductance response and blood oxygenation level-dependent responses in unmedicated adult patients with OCD (n = 27) and healthy participants (n = 22) submitted to a two-day fear-conditioning experiment comprising fear conditioning, extinction (day 1) and extinction recall (day 2). During conditioning, groups differed regarding the skin conductance reactivity to the aversive stimulus (shock) and regarding the activation of the right opercular cortex, insular cortex, putamen, and lingual gyrus in response to conditioned stimuli. During extinction recall, patients with OCD had higher responses to stimuli and smaller differences between responses to conditioned and neutral stimuli. For the entire sample, the higher the response delta between conditioned and neutral stimuli, the greater the dACC activation for the same contrast during early extinction recall. While activation of the dACC predicted the average difference between responses to stimuli for the entire sample, groups did not differ regarding the activation of the dACC during extinction recall. Larger unmedicated samples might be necessary to replicate the previous findings reported in patients with OCD.

Morphologic alterations of the fear circuitry: the role of sex hormones and oral contraceptives

Background

Endogenous sex hormones and oral contraceptives (OCs) have been shown to influence key regions implicated in fear processing. While OC use has been found to impact brain morphology, methodological challenges remain to be addressed, such as avoiding selection bias between OC users and non-users, as well as examining potential lasting effects of OC intake.

Objective

We investigated the current and lasting effects of OC use, as well as the interplay between the current hormonal milieu and history of hormonal contraception use on structural correlates of the fear circuitry. We also examined the role of endogenous and exogenous sex hormones within this network.

Methods

We recruited healthy adults aged 23-35 who identified as women currently using (n = 62) or having used (n = 37) solely combined OCs, women who never used any hormonal contraceptives (n = 40), or men (n = 41). Salivary endogenous sex hormones and current users' salivary ethinyl estradiol (EE) were assessed using liquid chromatography - tandem mass spectrometry. Using structural magnetic resonance imaging, we extracted surface-based gray matter volumes (GMVs) and cortical thickness (CT) for regions of interest of the fear circuitry. Exploratory whole-brain analyses were conducted with surface-based and voxel-based morphometry methods.

Results

Compared to men, all three groups of women exhibited a larger GMV of the dorsal anterior cingulate cortex, while only current users showed a thinner ventromedial prefrontal cortex. Irrespective of the menstrual cycle phase, never users exhibited a thicker right anterior insular cortex than past users. While associations with endogenous sex hormones remain unclear, we showed that EE dosage in current users had a greater influence on brain anatomy compared to salivary EE levels and progestin androgenicity, with lower doses being associated with smaller cortical GMVs.

Discussion

Our results highlight a sex difference for the dorsal anterior cingulate cortex GMV (a fear-promoting region), as well as a reduced CT of the ventromedial prefrontal cortex (a fear-inhibiting region) specific to current OC use. Precisely, this finding was driven by lower EE doses. These findings may represent structural vulnerabilities to anxiety and stress-related disorders. We showed little evidence of durable anatomical effects, suggesting that OC intake can (reversibly) affect fear-related brain morphology.

Case report: Anxiety and depression as initial symptoms in a patient with acute hypoxia and patent foramen ovale

The prevalence of patent foramen ovale (PFO) is 15-35% among adults. The role of right-to-left shunting through the PFO, anxiety, depression, and hypoxemia in the systemic circulation remains poorly understood. Herein, we present the case of a 52-year-old woman with no heart or lung disease, who was admitted due to anxiety for 5 months and had symptom exacerbation with dizziness for 4 days and presented with cyanosis. She was noted to have acute hypoxemia, with an oxygen saturation of 94.48% on room air, and arterial blood gas showed an oxygen tension of 65.64 mmHg. Agitated saline contrast echocardiography showed right-to-left shunting due to PFO. Arteriovenous fistula, pneumonia, pulmonary embolism, pulmonary hypertension, congestion peripheral cyanosis, ischemic peripheral cyanosis, and methemoglobin were excluded. Additionally, the patient improved by taking Paroxetine, Oxazepam, and Olanzapine. Her oxygen tension returned to 90.42 mmHg, and her symptoms resolved. In the case of severe anxiety and depression, right-to-left shunting through the PFO may cause acute systemic hypoxemia via a flow-driven mechanism, occasionally manifesting as cyanosis. When anxiety improved, hypoxia also improved. Thus, the treatment of anxiety and depression seems effective in improving hypoxemia. Notably, this is a rare report, and we hope to draw the attention of psychosomatic specialists, psychiatrists, and clinicians to seek the relationship between anxiety appearing as acute stress and PFO. This may be a new therapeutic method for treating severe anxiety disorder.

Anxiety as a disorder of uncertainty: implications for understanding maladaptive anxiety, anxious avoidance, and exposure therapy

In cognitive-behavioral conceptualizations of anxiety, exaggerated threat expectancies underlie maladaptive anxiety. This view has led to successful treatments, notably exposure therapy, but is not consistent with the empirical literature on learning and choice alterations in anxiety. Empirically, anxiety is better described as a disorder of uncertainty learning. How disruptions in uncertainty lead to impairing avoidance and are treated with exposure-based methods, however, is unclear. Here, we integrate concepts from neurocomputational learning models with clinical literature on exposure therapy to propose a new framework for understanding maladaptive uncertainty functioning in anxiety. Specifically, we propose that anxiety disorders are fundamentally disorders of uncertainty learning and that successful treatments, particularly exposure therapy, work by remediating maladaptive avoidance from dysfunctional explore/exploit decisions in uncertain, potentially aversive situations. This framework reconciles several inconsistencies in the literature and provides a path forward to better understand and treat anxiety.

Gray matter associations with extinction-induced neural activation in patients with anxiety disorders

The relationship between structural characteristics and extinction-induced brain activations in anxiety disorders (ANX) remains a space for greater exploration. In this study, we assessed gray matter volume (GMV) and its associated functional activations during fear extinction memory recall in an ANX cohort. We performed voxel-based morphometry analysis to examine GMVs from ANX (n = 92) and controls (n = 73). We further examined the correlation between GMVs and extinction-induced neural activations during recall across groups. In the patients' group, we observed decreased GMV in the anterior hippocampus and increased GMV in the dorsolateral prefrontal cortex (dlPFC). Hippocampal volume was positively correlated with ventromedial prefrontal cortex activation in healthy controls, while it was negatively correlated with dorsal anterior cingulate cortex (dACC) activation in ANX. The dlPFC volume was positively correlated with activations of dACC, pre- and post-central gyrus, and supramarginal gyrus only in healthy controls. Therefore, the link between structural and functional imbalance within the hippocampus and dlPFC might contribute to the pathophysiology of ANX. In the controls, the relationship between structural variance in the hippocampus and dlPFC and extinction-induced neural activations is consistent with a greater ability to regulate fear responding; associations that were absent in the ANX cohort. Furthermore, our findings of structure-function abnormalities within key nodes of emotional homeostasis in ANX point to dlPFC as a potential neural node to target using neuromodulation tools.

Don't worry, it won't be fine. Contributions of worry and anxious arousal to startle responses and event-related potentials in threat anticipation

A widely shared framework suggests that anxiety maps onto two dimensions: anxious apprehension and anxious arousal. Previous research linked individual differences in these dimensions to differential neural response patterns in neuropsychological, imaging, and physiological studies. Differential effects of the anxiety dimensions might contribute to inconsistencies in prior studies that examined neural processes underlying anxiety, such as hypersensitivity to unpredictable threat. We investigated the association between trait worry (as a key component of anxious apprehension), anxious arousal, and the neural processing of anticipated threat. From a large online community sample (N = 1,603), we invited 136 participants with converging and diverging worry and anxious arousal profiles into the laboratory. Participants underwent the NPU-threat test with alternating phases of unpredictable threat, predictable threat, and safety, while physiological responses (startle reflex and startle probe locked event-related potential components N1 and P3) were recorded. Worry was associated with increased startle responses to unpredictable threat and increased attentional allocation (P3) to startle probes in predictable threat anticipation. Anxious arousal was associated with increased startle and N1 in unpredictable threat anticipation. These results suggest that trait variations in the anxiety dimensions shape the dynamics of neural processing of threat. Specifically, trait worry seems to simultaneously increase automatic defensive preparation during unpredictable threat and increase attentional responding to threat-irrelevant stimuli during predictable threat anticipation. The current study highlights the utility of anxiety dimensions to understand how physiological responses during threat anticipation are altered in anxiety and supports that worry is associated with hypersensitivity to unpredictable, aversive contexts.

Vulnerability to anxiety differently predicts cortisol reactivity and state anxiety during a laboratory stressor in healthy girls and boys

BACKGROUND

Children diagnosed with anxiety disorders show altered cortisol and state anxiety reactivity to stressful situations. To date, it remains unclear whether these dysregulations emerge after the pathology or whether they are also detectable in healthy children. If the latter is true, this may provide insight into children's vulnerability to develop clinical anxiety. Various personality factors (anxiety sensitivity, intolerance of uncertainty, perseverative cognitions) increase youth's vulnerability to develop anxiety disorders. This study aimed to examine whether vulnerability to anxiety was associated with cortisol reactivity and state anxiety in healthy youth.

METHODS

114 children (8-12 y/o) were exposed to the Trier Social Stress Test for Children (TSST-C), where saliva samples were collected for cortisol quantification. State anxiety was assessed 20 min before and 10 min after the TSST-C using the state form of the State-Trait Anxiety Inventory for Children. Vulnerability to anxiety was assessed using a composite score of the Childhood Anxiety Sensitivity Index, Intolerance of Uncertainty Scale for Children, and Perseverative Thinking Questionnaire.

RESULTS

Higher vulnerability to anxiety was associated with enhanced cortisol reactivity in boys. Irrespective of vulnerability level, girls reported greater changes in state anxiety in response to the TSST.

LIMITATIONS

Given the correlational nature of this study, the directionality of the results remains to be elucidated.

CONCLUSIONS

These results indicate that endocrine patterns characterizing anxiety disorders are detectable in healthy boys who exhibit a high level of self-reported vulnerability to anxiety. These results could aid in the early identification of children at risk of developing anxiety disorders.

Alleviating anxiety and taming trauma: Novel pharmacotherapeutics for anxiety disorders and posttraumatic stress disorder

Psychiatric disorders associated with psychological trauma, stress and anxiety are a highly prevalent and increasing cause of morbidity worldwide. Current therapeutic approaches, including medication, are effective in alleviating symptoms of anxiety disorders and posttraumatic stress disorder (PTSD), at least in some individuals, but have unwanted side-effects and do not resolve underlying pathophysiology. After a period of stagnation, there is renewed enthusiasm from public, academic and commercial parties in designing and developing drug treatments for these disorders. Here, we aim to provide a snapshot of the current state of this field that is written for neuropharmacologists, but also practicing clinicians and the interested lay-reader. After introducing currently available drug treatments, we summarize recent/ongoing clinical assessment of novel medicines for anxiety and PTSD, grouped according to primary neurochemical targets and their potential to produce acute and/or enduring therapeutic effects. The evaluation of putative treatments targeting monoamine (including psychedelics), GABA, glutamate, cannabinoid, cholinergic and neuropeptide systems, amongst others, are discussed. We emphasize the importance of designing and clinically assessing new medications based on a firm understanding of the underlying neurobiology stemming from the rapid advances being made in neuroscience. This includes harnessing neuroplasticity to bring about lasting beneficial changes in the brain rather than - as many current medications do - produce a transient attenuation of symptoms, as exemplified by combining psychotropic/cognitive enhancing drugs with psychotherapeutic approaches. We conclude by noting some of the other emerging trends in this promising new phase of drug development.

Understanding clinical fear and anxiety through the lens of human fear conditioning

Fear is an adaptive emotion that mobilizes defensive resources upon confrontation with danger. However, fear becomes maladaptive and can give rise to the development of clinical anxiety when it exceeds the degree of threat, generalizes broadly across stimuli and contexts, persists after the danger is gone or promotes excessive avoidance behaviour. Pavlovian fear conditioning has been the prime research instrument that has led to substantial progress in understanding the multi-faceted psychological and neurobiological mechanisms of fear in past decades. In this Perspective, we suggest that fruitful use of Pavlovian fear conditioning as a laboratory model of clinical anxiety requires moving beyond the study of fear acquisition to associated fear conditioning phenomena: fear extinction, generalization of conditioned fear and fearful avoidance. Understanding individual differences in each of these phenomena, not only in isolation but also in how they interact, will further strengthen the external validity of the fear conditioning model as a tool with which to study maladaptive fear as it manifests in clinical anxiety.

Parent-child physiological concordance predicts stronger observational fear learning in children with a less secure relationship with their parent

Observational fear learning is common in children as they learn to fear by observing their parents. Although adaptive, it can also contribute to the development of fear-related psychopathologies such as anxiety disorders. Therefore, it is important to identify and study the factors that modulate children's sensitivity to observational fear learning. For instance, observational fear learning can be facilitated by the synchronization of biological systems between two people. In parent-child dyads, physiological concordance is important and varies according to the attachment relationship, among others. We investigated the joint effect of parent-child physiological concordance and attachment on observational fear learning in children. A total of 84 parent-child dyads participated in this study. Parents were filmed while exposed to a fear-conditioning protocol, where one stimulus was associated with a shock (CS+) and the other was not (CS-). This recording was then shown to the children (observational learning). Thereafter, both stimuli (CS+ and CS-) were presented to the children without any shock (direct expression test). For both the parent and child, skin conductance activity was recorded throughout the entire procedure. We measured physiological concordance between the parent's phasic skin conductance signal during conditioning and the child's signal during the observational learning stage. Children showing stronger concordance and a less secure relationship with their parent exhibited higher levels of fear to the CS+, as indicated by a heightened skin conductance response during the direct expression test. Thus, when children have an insecure relationship with their parent, strong physiological concordance may increase their sensitivity to observational fear learning.

Feasibility of the virtual reality-based assessments in patients with panic disorder

Introduction

Recurrences and diagnostic instability of panic disorder (PD) are common and have a negative effect on its long-term course. Developing a novel assessment tool for anxiety that can be used in a multimodal approach may improve these problems in panic disorder patients. This study assessed the feasibility of virtual reality-based assessment in panic disorder (VRA-PD).

Methods

Twenty-five patients with PD (ANX group) and 28 healthy adults (CON group) participated in the study. VRA-PD consisted of four modules based on the key components of cognitive behavior therapy for an anxiety disorder: "Baseline evaluation module" (M0), "Daily environment exposure module" (M1), "Relaxation module" (M2), and "Interoceptive exposure module" (M3). Multiple evaluations, including self-rating anxiety scores (AS) and physiological responses [heart rate variability (HRV) index], were performed in three steps at M1, M2, and M3, and once at M0. Comparisons between patients with PD and healthy controls, factor analysis of variables in VRA-PD, changes in responses within modules, and correlation analysis between variables in VRA-PD and anxiety symptoms assessed by psychological scales were performed.

Results

All participants completed the VRA-PD without discontinuation. The ANX group reported significantly higher AS for all steps and a smaller HRV index in M1 (steps 1 and 2) and M2 (step 1). Repeated-measures analysis of covariance (ANCOVA) revealed significant interaction effects for AS in M1 (F = 4.09, p = 0.02) and M2 (F = 4.20, p = 0.02), and HRV index in M2 (F = 16.22, p < 0.001) and M3 (F = 21.22, p = 0.02). The HRV index only indicated a good model fit for the three-factor model, reflecting the construct of the VRA-PD. Both AS and HRV indexes were significantly correlated with anxiety and depression symptoms.

Discussion

The current study provides preliminary evidence that the VRA-PD could be a valid anxiety behavior assessment tool.

Fear Extinction Learning in Posttraumatic Stress Disorder

Impairments in fear extinction processes have been implicated in the genesis and maintenance of debilitating psychopathologies, including Posttraumatic stress disorder (PTSD). PTSD, classified as a trauma- and stressor-related disorder, is characterized by four symptom clusters: intrusive recollections of trauma, avoidance of trauma-related stimuli, alterations in cognition and mood, and hyperarousal. One of the key pathological feature associated with the persistence of these symptoms is impaired fear extinction, as delineated in multiple studies employing Pavlovian fear-conditioning paradigms. These paradigms, comprising fear acquisition, extinction, extinction recall, and fear renewal phases, have illuminated the neurobiological substrates of PTSD. Dysfunctions in the neural circuits that mediate these fear learning and extinction processes can result in failure to extinguish fear responses and retain extinction memory, giving rise to enduring experience of fear and anxiety. The protective avoidance behaviors observed in individuals with PTSD further exacerbate intrusive symptoms and pose challenges to effective treatment strategies. A comprehensive analysis of fear conditioning and extinction processes, along with the underlying neurobiology, could significantly enhance our understanding of PTSD pathophysiology. This chapter delineates the role of fear extinction processes in PTSD, investigates the underlying neurobiological substrates, and underscores the therapeutic implications, while also identifying future research directions.

Is Fear Extinction Impairment Central to Psychopathology?

As discussed in this chapter, there have been enormous advances in our understanding of how anxiety disorders develop, are maintained, and can be treated. Many of these advances have been the result of translational studies using fear conditioning and extinction models. Despite these successes, we recognize, as a field, that there are important limitations in the extent to which extinction can explain how anxiety disorders and behaviors remit. Clinically speaking, the outstanding challenge for treatment of anxiety disorders is to improve the current suboptimal success rates. Over the past 30 years, we have not improved our treatment success rates despite employing many pharmacological and pharmacological strategies. While extinction and related fear circuitry mechanisms most certainly appear to play a role in treatment of anxiety disorders, they are also apparently insufficient to fully accommodate the varied responses individuals exhibit with this treatment approach. Increasingly diverse and innovative approaches are needed that accommodate the multitude of change mechanisms involved in treating anxiety. However, this is not to suggest ignoring the key role that extinction and memory updating processes play in overcoming anxiety.

Causally mapping human threat extinction relevant circuits with depolarizing brain stimulation methods

Laboratory threat extinction paradigms and exposure-based therapy both involve repeated, safe confrontation with stimuli previously experienced as threatening. This fundamental procedural overlap supports laboratory threat extinction as a compelling analogue of exposure-based therapy. Threat extinction impairments have been detected in clinical anxiety and may contribute to exposure-based therapy non-response and relapse. However, efforts to improve exposure outcomes using techniques that boost extinction - primarily rodent extinction - have largely failed to date, potentially due to fundamental differences between rodent and human neurobiology. In this review, we articulate a comprehensive pre-clinical human research agenda designed to overcome these failures. We describe how connectivity guided depolarizing brain stimulation methods (i.e., TMS and DBS) can be applied concurrently with threat extinction and dual threat reconsolidation-extinction paradigms to causally map human extinction relevant circuits and inform the optimal integration of these methods with exposure-based therapy. We highlight candidate targets including the amygdala, hippocampus, ventromedial prefrontal cortex, dorsal anterior cingulate cortex, and mesolimbic structures, and propose hypotheses about how stimulation delivered at specific learning phases could strengthen threat extinction.

Translating Big Data to Clinical Outcomes in Anxiety: Potential for Multimodal Integration

PURPOSE OF THE REVIEW

This review describes approaches to research on anxiety that attempt to link neural correlates to treatment response and novel therapies. The review emphasizes pediatric anxiety disorders since most anxiety disorders begin before adulthood.

RECENT FINDINGS

Recent literature illustrates how current treatments for anxiety manifest diverse relations with a range of neural markers. While some studies demonstrate post-treatment normalization of markers in anxious individuals, others find persistence of group differences. For other markers, which show no pretreatment association with anxiety, the markers nevertheless distinguish treatment-responders from non-responders. Heightened error related negativity represents the risk marker discussed in the most depth; however, limitations in measures related to error responding necessitate multimodal and big-data approaches. Single risk markers show limits as correlates of treatment response. Large-scale, multimodal data analyzed with predictive models may illuminate additional risk markers related to anxiety disorder treatment outcomes. Such work may identify novel targets and eventually guide improvements in treatment response/outcomes.

Revisiting sex differences in the acquisition and extinction of threat conditioning in humans

Findings pertaining to sex differences in the acquisition and extinction of threat conditioning, a paradigm widely used to study emotional homeostasis, remain inconsistent, particularly in humans. This inconsistency is likely due to multiple factors, one of which is sample size. Here, we pooled functional magnetic resonance imaging (fMRI) and skin conductance response (SCR) data from multiple studies in healthy humans to examine sex differences during threat conditioning, extinction learning, and extinction memory recall. We observed increased functional activation in males, relative to females, in multiple parietal and frontal (medial and lateral) cortical regions during acquisition of threat conditioning and extinction learning. Females mainly exhibited higher amygdala activation during extinction memory recall to the extinguished conditioned stimulus and also while responding to the unconditioned stimulus (presentation of the shock) during threat conditioning. Whole-brain functional connectivity analyses revealed that females showed increased connectivity across multiple networks including visual, ventral attention, and somatomotor networks during late extinction learning. At the psychophysiological level, a sex difference was only observed during shock delivery, with males exhibiting higher unconditioned responses relative to females. Our findings point to minimal to no sex differences in the expression of conditioned responses during acquisition and extinction of such responses. Functional MRI findings, however, show some distinct functional activations and connectivities between the sexes. These data suggest that males and females might use different neural mechanisms, mainly related to cognitive processing, to achieve comparable levels of acquired conditioned responses to threating cues.

A meta-analysis of conditioned fear generalization in anxiety-related disorders

Generalization of conditioned fear is adaptive in some situations but maladaptive when fear excessively generalizes to innocuous stimuli with incidental resemblance to a genuine threat cue. Recently, empirical interest in fear generalization as a transdiagnostic explanatory mechanism underlying anxiety-related disorders has accelerated. As there are now several studies of fear generalization across multiple types of anxiety-related disorders, the authors conducted a meta-analysis of studies reporting behavioral measures (subjective ratings and psychophysiological indices) of fear generalization in anxiety-related disorder vs. comparison groups. We conducted systematic searches of electronic databases (conducted from January-October 2020) for fear generalization studies involving anxiety-related disorder groups or subclinical analog groups. A total of 300 records were full-text screened and two unpublished datasets were obtained, yielding 16 studies reporting behavioral fear generalization measures. Random-effects meta-analytic models and meta-regressions were applied to the identified data. Fear generalization was significantly heightened in anxiety-related disorder participants (N = 439) relative to comparison participants (N = 428). We did not identify any significant clinical, sample, or methodological moderators. Heightened fear generalization is quantitatively supported as distinguishing anxiety-related disorder groups from comparison groups. Evidence suggests this effect is transdiagnostic, relatively robust to experimental or sample parameters, and that generalization paradigms are a well-supported framework for neurobehavioral investigations of learning and emotion in anxiety-related disorders. We discuss these findings in the context of prior fear conditioning meta-analyses, past neuroimaging investigations of fear generalization in anxiety-related disorders, and future directions and challenges for the field.

Temporally and anatomically specific contributions of the human amygdala to threat and safety learning

Pavlovian threat learning is a primary translational model for understanding the brain systems that underlie anxiety and trauma-related psychopathology. The amygdala has traditionally played a central role in this important form of learning across species. However, recent human neuroimaging work has revealed inconsistent findings regarding the role of human amygdala in threat and safety learning. To address this discrepancy, we examined amygdala responses to threat-predictive cues in a large sample of human participants. We found robust evidence for amygdala responses during threat conditioning and, further, that these responses occurred in a temporally and anatomically specific manner. Our results reveal clear evidence of human amygdala involvement in associative learning and offer insight into why some neuroimaging work has yielded equivocal findings.

Neural plasticity in subareas of the rodent amygdala is widely known to be essential for Pavlovian threat conditioning and safety learning. However, less consistent results have been observed in human neuroimaging studies. Here, we identify and test three important factors that may contribute to these discrepancies: the temporal profile of amygdala response in threat conditioning, the anatomical specificity of amygdala responses during threat conditioning and safety learning, and insufficient power to identify these responses. We combined data across multiple studies using a well-validated human threat conditioning paradigm to examine amygdala involvement during threat conditioning and safety learning. In 601 humans, we show that two amygdala subregions tracked the conditioned stimulus with aversive shock during early conditioning while only one demonstrated delayed responding to a stimulus not paired with shock. Our findings identify cross-species similarities in temporal- and anatomical-specific amygdala contributions to threat and safety learning, affirm human amygdala involvement in associative learning and highlight important factors for future associative learning research in humans.

Behavioral and neural responses during fear conditioning and extinction in a large transdiagnostic sample

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Behavioral and neural responses during Pavlovian fear learning were examined in a large sample of healthy and individuals with anxiety and depression.

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Latent profile models to threat were derived from behavioral and neural data.

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Demographic, cognitive, and psychological variables did not robustly characterize latent profiles.

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Neuroimaging data did not evidence functional role of amygdala in fear learning.

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Human fear learning recruited a distributed network of regions involved in interoceptive, cognitive, motivational, and psychomotor processes.

Background

Dysregulation of fear learning has been associated with psychiatric disorders that have altered positive and negative valence domain function. While amygdala-insula-prefrontal circuitry is considered important for fear learning, there have been inconsistencies in neural findings in healthy and clinical human samples. This study aimed to delineate the neural substrates and behavioral responses during fear learning in a large, transdiagnostic sample with predominantly depressive and/or anxious dysfunction.

Methods

Two-hundred and eighty-two individuals (52 healthy participants; 230 participants with depression and/or anxiety-related problems) from the Tulsa 1000 study, an ongoing, naturalistic longitudinal study based on a dimensional psychopathological framework, completed a Pavlovian fear learning task during functional magnetic resonance imaging. Linear mixed-effects analyses examined condition-by-time effects on brain activation (CS+, CS- across familiarization, conditioning, and extinction trials). A data-driven latent profile analysis (LPA) examined distinct patterns of behavioral and neural responses to threat across fear conditioning and extinction, while logistic regression analyses evaluated cognitive-affective predictors of latent profiles.

Results

Whole-brain analyses revealed a condition-by-time interaction in the anterior insula, postcentral gyrus, superior temporal gyrus, middle frontal gyrus, and cerebellum but not amygdala. The LPA identified distinct latent profiles across subjective and neural levels of measurement. Anterior insula profiles were characterized by marginal differences in age and state anxiety.

Conclusions

Our findings demonstrate that human fear learning recruits a distributed network of regions involved in interoceptive, cognitive, motivational, and psychomotor processes. Data-driven analyses identified distinct profiles of subjective and neural responses during fear learning that transcended clinical diagnoses, but no robust relationships to demographic or cognitive-affective variable were identified.

Abnormal dynamic functional connectivity during fear extinction learning in PTSD and anxiety disorders

Examining the neural circuits of fear/threat extinction advanced our mechanistic understanding of several psychiatric disorders, including anxiety disorders (AX) and posttraumatic stress disorder (PTSD). More is needed to understand the interplay of large-scale neural networks during fear extinction in these disorders. We used dynamic functional connectivity (FC) to study how FC might be perturbed during conditioned fear extinction in individuals with AX or PTSD. We analyzed neuroimaging data from 338 individuals that underwent a two-day fear conditioning and extinction paradigm. The sample included healthy controls (HC), trauma-exposed non-PTSD controls, and patients diagnosed with AX or PTSD. Dynamic FC during extinction learning gradually increased in the HC group but not in patient groups. The lack of FC change in patients was predominantly observed within and between the default mode, frontoparietal control, and somatomotor networks. The AX and PTSD groups showed impairments in different, yet partially overlapping connections especially involving the dorsolateral prefrontal cortex. Extinction-induced FC predicted ventromedial prefrontal cortex activation and FC during extinction memory recall only in the HC group. FC impairments during extinction learning correlated with fear- and anxiety-related clinical measures. These findings suggest that relative to controls, individuals with AX or PTSD exhibited widespread abnormal FC in higher-order cognitive and attention networks during extinction learning and failed to establish a link between neural signatures during extinction learning and memory retrieval. This failure might underlie abnormal processes related to the conscious awareness, attention allocation, and sensory processes during extinction learning and retrieval in fear- and anxiety-related disorders.

The Computations of a Traumatized Mind: A Latent Cause Model of Posttraumatic Stress Disorder

In cognitive psychology, a recent perspective based on the notion of latent cause (LC) has offered new insight on how learning and memory work. Here I explore the implications of this novel perspective to understand posttraumatic stress disorder (PTSD). The proposal is that, because of a propensity to interpret events as manifestations of multiple LCs (a propensity facilitated by experiencing traumas in childhood), PTSD patients form an LC associated with the trauma and that this LC is responsible for typical symptoms of the illness (specifically, intrusive symptoms and associated fear). Later, after the trauma, some patients develop a second LC, now associated with the presence of trauma-related cues combined with absence of danger. Development of the latter LC would interfere with extinction and explain why, for some patients, exposure to trauma-related cues (even when supported by interventions such as exposure protocols) fails to provide much improvement. This proposal has potential clinical implications, raising the possibility that some patients might benefit from exposure to mildly painful aspects of the trauma in conjunction with trauma-related cues.

Parsing neural circuits of fear learning and extinction across basic and clinical neuroscience: Towards better translation

Over the past decades, studies of fear learning and extinction have advanced our understanding of the neurobiology of threat and safety learning. Animal studies can provide mechanistic/causal insights into human brain regions and their functional connectivity involved in fear learning and extinction. Findings in humans, conversely, may further enrich our understanding of neural circuits in animals by providing macroscopic insights at the level of brain-wide networks. Nevertheless, there is still much room for improvement in translation between basic and clinical research on fear learning and extinction. Through the lens of neural circuits, in this article, we aim to review the current knowledge of fear learning and extinction in both animals and humans, and to propose strategies to fill in the current knowledge gap for the purpose of enhancing clinical benefits.

A longitudinal investigation of psychological distress in children during COVID-19: the role of socio-emotional vulnerability

BACKGROUND

Although the COVID-19 pandemic has increased the incidence of distress in youth, some children show increased resilience, emphasizing the need to better understand the predictors of distress in youth.

OBJECTIVE

This longitudinal study aimed to assess the combined impact of known socio-emotional predictors of stress-related psychopathology, namely anxiety sensitivity, anxiety trait, intolerance to uncertainty, and rumination, on COVID-related distress in healthy youth.

METHOD

A total of 92 parent-child dyads that previously participated in a laboratory-based experiment assessing observational fear learning in families between 2017 and 2019 (T0) were recontacted. Of them, 84 children aged between 9 and 14 agreed to participate. They completed online questionnaires in June 2020 (T1), September 2020 (T2), December 2020 (T3), and March 2021 (T4). Participants were free of mental illness at T0 and T1. To create a socio-emotional composite score (SECS), we measured anxiety sensitivity (Childhood Anxiety Sensitivity Index) at T0, trait anxiety (Trait subscale of the State-Trait Anxiety Inventory for Children (STAI-C)), intolerance to uncertainty (Intolerance of Uncertainty Scale for Children), and trait rumination (Children's Response Style Scale) at T1 and created a weighted z-score. To assess symptoms of anxiety, post-traumatic stress (PTS), and depression in reaction to COVID-19, participants completed the State subscale of the STAI-C, the Children's Revised Impact of Event Scale, and the Children's Depression Inventory at T1-T4. Three general linear models were run with sex, age group (9-11 and 12+ years old), and SECS as predictors.

RESULTS

Analyses revealed a SECS*Time interaction, with higher SECS predicting elevated anxiety symptoms at T1 and T4, and elevated PTS symptoms at T1 and T2.

CONCLUSION

These results suggest that healthy youth endorsing high levels of socio-emotional vulnerability to psychopathology have a higher risk of suffering from anxiety and PTS, but not depressive symptoms, in the year following a major stressor.

A Multivoxel Pattern Analysis of Anhedonia During Fear Extinction: Implications for Safety Learning

BACKGROUND

Pavlovian learning processes are central to the etiology and treatment of anxiety disorders. Anhedonia and related perturbations in reward processes have been implicated in Pavlovian learning. Associations between anhedonia symptoms and neural indices of Pavlovian learning can inform transdiagnostic associations among depressive and anxiety disorders.

METHODS

Participants ages 18 to 19 years (67% female) completed a fear extinction (n = 254) and recall (n = 249) paradigm during functional magnetic resonance imaging. Symptom dimensions of general distress (common to anxiety and depression), fears (more specific to anxiety), and anhedonia-apprehension (more specific to depression) were evaluated. We trained whole-brain multivoxel pattern decoders for anhedonia-apprehension during extinction and extinction recall and tested the decoders' ability to predict anhedonia-apprehension in an external validation sample. Specificity analyses examined effects covarying for general distress and fears. Decoding was repeated within canonical brain networks to highlight candidate neurocircuitry underlying whole-brain effects.

RESULTS

Whole-brain decoder training succeeded during both tasks. Prediction of anhedonia-apprehension in the external validation sample was successful for extinction (R² = 0.047; r = 0.276, p = .002) but not extinction recall (R² < 0.001, r = -0.063, p = .492). The extinction decoder remained significantly associated with anhedonia-apprehension covarying for fears and general distress (t₁₂₁ = 3.209, p = .002). Exploratory results highlighted activity in the cognitive control, default mode, limbic, salience, and visual networks related to these effects.

CONCLUSIONS

Results suggest that patterns of brain activity during extinction, particularly in the cognitive control, default mode, limbic, salience, and visual networks, can be predictive of anhedonia symptoms. Future research should examine associations between anhedonia and extinction, including studies of exposure therapy or positive affect treatments among anhedonic individuals.

Is there a neuroscience-based, mechanistic rationale for transcranial direct current stimulation as an adjunct treatment for posttraumatic stress disorder?

It is well-known that there is considerable variation in the effectiveness of evidence-based treatments for psychiatric disorders, and a continued need to improve the real-world effectiveness of these treatments. In the last 20+ years the examination of noninvasive brain stimulation techniques for psychiatric treatment has increased dramatically. However, in order to test these techniques for effective therapeutic use, it is critical to understand (a) (what are) the key neural circuits to engage for specific disorders or clusters of symptoms, and (b) (how) can these circuits be reached effectively using neurostimulation? Here we focus on the research toward the application of transcranial direct current stimulation (tDCS) for posttraumatic stress disorder (PTSD). tDCS is a portable and inexpensive technique that lends itself well to be combined with, and thus potentially augment, exposure-based treatment for PTSD. In this review, we discuss the behavioral model of threat and safety learning and memory as it relates to PTSD, the underlying neurobiology of PTSD, as well as the current understandings of tDCS action, including its limitations and opportunities. Through this lens, we summarize the research on the application of tDCS to modulated threat and safety learning and memory to date, and propose new directions for its future research. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Impact of exogenous estradiol on task-based and resting-state neural signature during and after fear extinction in healthy women

Fluctuations of endogenous estrogen modulates fear extinction, but the influence of exogenous estradiol is less studied. Moreover, little focus has been placed on the impact of estradiol on broad network connectivity beyond the fear extinction circuit. Here, we examined the effect of acute exogenous estradiol administration on fear extinction-induced brain activation, whole-brain functional connectivity (FC) during the fear extinction task and post-extinction resting-state. Ninety healthy women (57 using oral contraceptives [OC], 33 naturally cycling [NC]) were fear conditioned on day 1. They ingested an estradiol or placebo pill prior to extinction learning on day 2 (double-blind design). Extinction memory was assessed on day 3. Task-based functional MRI data were ascertained on days 2 and 3 and resting-state data were collected post-extinction on day 2 and pre-recall on day 3. Estradiol administration significantly modulated the neural signature associated with fear extinction learning and memory, consistent with prior studies. Importantly, estradiol administration induced significant changes in FC within multiple networks, including the default mode and somatomotor networks during extinction learning, post-extinction, and during extinction memory recall. Exploratory analyses revealed that estradiol impacted ventromedial prefrontal cortex (vmPFC) activation and FC differently in the NC and OC women. The data implicate a more diffused and significant effect of acute estradiol administration on multiple networks. Such an effect might be beneficial to modulating attention and conscious processes in addition to engaging neural processes associated with emotional learning and memory consolidation.

Exposure to intimate partner aggression during childhood is associated with blunted skin conductance recovery following stress in early adulthood

This study examines skin conductance level (SCL) trajectories and childhood exposure to intimate partner aggression (IPA) committed between parents in a sample of college students. Although IPA among parents does not directly involve children, children frequently see or are exposed to IPA first-hand when it occurs. This exposure to IPA increases risks for psychopathology and emotional or behavioral difficulties for children or adolescents later in life. However, research has not yet examined the stress response patterns of individuals exposed to IPA, nor how reactivity to stress may be altered based on this exposure. Participants included 161 college students who completed questionnaires assessing demographics, mental health, and exposure to IPA, and also reported on family functioning and parental drinking habits. Additionally, participants completed a three-minute mirror tracing task followed by a three-minute recovery period while SCL was monitored. Multilevel modeling was used to assess whether frequency or level of exposure to IPA was related to trajectories of SCL. Neither variable was related to SCL trajectories during the mirror-tracing task. However, both frequency and level of exposure were related to SCL trajectories during the recovery period, such that for participants reporting higher levels of either IPA exposure variable, SCL trajectories during recovery declined less rapidly and did not decline to as low of a level compared to participants reporting lower levels of IPA exposure. This blunted SCL recovery may be due to wear and tear from repeated innervation, or a calibrating of the SCL response to adapt to a volatile home environment.

Neural mediators of subjective and autonomic responding during threat learning and regulation

Threat learning elicits robust changes across multiple affective domains, including changes in autonomic indices and subjective reports of fear and anxiety. It has been argued that the underlying causes of such changes may be dissociable at a neural level, but there is currently limited evidence to support this notion. To address this, we examined the neural mediators of trial-by-trial skin conductance responses (SCR), and subjective reports of anxious arousal and valence in participants (n = 27; 17 females) performing a threat reversal task during ultra-high field functional magnetic resonance imaging. This allowed us to identify brain mediators during initial threat learning and subsequent threat reversal. Significant neural mediators of anxious arousal during threat learning included the dorsal anterior cingulate, anterior insula cortex (AIC), and ventromedial prefrontal cortex (vmPFC), subcortical regions including the amygdala, ventral striatum, caudate and putamen, and brain-stem regions including the pons and midbrain. By comparison, autonomic changes (SCR) were mediated by a subset of regions embedded within this broader circuitry that included the caudate, putamen and thalamus, and two distinct clusters within the vmPFC. The neural mediators of subjective negative valence showed prominent effects in posterior cortical regions and, with the exception of the AIC, did not overlap with threat learning task effects. During threat reversal, positive mediators of both subjective anxious arousal and valence mapped to the default mode network; this included the vmPFC, posterior cingulate, temporoparietal junction, and angular gyrus. Decreased SCR during threat reversal was positively mediated by regions including the mid cingulate, AIC, two sub-regions of vmPFC, the thalamus, and the hippocampus. Our findings add novel evidence to support distinct underlying neural processes facilitating autonomic and subjective responding during threat learning and threat reversal. The results suggest that the brain systems engaged in threat learning mostly capture the subjective (anxious arousal) nature of the learning process, and that appropriate responding during threat reversal is facilitated by participants engaging self- and valence-based processes. Autonomic changes (SCR) appear to involve distinct facilitatory and regulatory contributions of vmPFC sub-regions.

Cortical and subcortical brain structure in generalized anxiety disorder: findings from 28 research sites in the ENIGMA-Anxiety Working Group

The goal of this study was to compare brain structure between individuals with generalized anxiety disorder (GAD) and healthy controls. Previous studies have generated inconsistent findings, possibly due to small sample sizes, or clinical/analytic heterogeneity. To address these concerns, we combined data from 28 research sites worldwide through the ENIGMA-Anxiety Working Group, using a single, pre-registered mega-analysis. Structural magnetic resonance imaging data from children and adults (5-90 years) were processed using FreeSurfer. The main analysis included the regional and vertex-wise cortical thickness, cortical surface area, and subcortical volume as dependent variables, and GAD, age, age-squared, sex, and their interactions as independent variables. Nuisance variables included IQ, years of education, medication use, comorbidities, and global brain measures. The main analysis (1020 individuals with GAD and 2999 healthy controls) included random slopes per site and random intercepts per scanner. A secondary analysis (1112 individuals with GAD and 3282 healthy controls) included fixed slopes and random intercepts per scanner with the same variables. The main analysis showed no effect of GAD on brain structure, nor interactions involving GAD, age, or sex. The secondary analysis showed increased volume in the right ventral diencephalon in male individuals with GAD compared to male healthy controls, whereas female individuals with GAD did not differ from female healthy controls. This mega-analysis combining worldwide data showed that differences in brain structure related to GAD are small, possibly reflecting heterogeneity or those structural alterations are not a major component of its pathophysiology.

Dysregulation of threat neurociruitry during fear extinction: the role of anhedonia

Dimensional models of anxiety and depression highlight common and distinct symptom clusters that are thought to reflect disruptions in underlying functional processes. The current study investigated how functioning of threat neurocircuitry relates to symptom dimensions of anxiety and depression. Participants were aged 18-19 years (n = 229, 158 female) and were selected to ensure a range of scores on symptom measures. Symptom dimensions of "General Distress" (common to anxiety disorders and depression), "Fears" (more specific to anxiety disorders), and "Anhedonia-apprehension" (more specific to depression) were evaluated. Participants underwent functional magnetic resonance imaging during a Pavlovian fear conditioning paradigm. Multilevel modeling analyses estimated relationships between symptom dimensions and activation in threat neural circuitry. Exploratory whole brain analyses were also conducted. Threat-related neural activity was not associated with General Distress or Fears. Anhedonia-apprehension was associated with activation of bilateral amygdala, anterior insula and dACC during late extinction. We found no evidence to support an association between symptom dimensions of General Distress or Fears with threat circuitry activation in a large sample of young adults. We did, however, find that the symptom dimension of Anhedonia-apprehension was significantly associated with threat-related neural activation during fear extinction. This effect requires replication in future work but may reflect anhedonic impairments in learning when contingencies are altered, possibly linked to the rewarding relief of an unexpectedly absent threat.

Experimental models in psychopathology research: The relation between Research Domain Criteria and Experimental Psychopathology

Experimental Psychopathology (EPP) and the Research Domain Criteria (RDoC) are research approaches that have developed in parallel, providing inter-related yet different scientific frameworks to investigate psychopathology at the intersection of fundamental and applied research. Here we address the overlap and differences between RDoC and EPP, and the challenges that both approaches face. Although overlap between EPP and RDoC can be clearly observed, each approach has its own unique strengths and weaknesses. These aspects will be illustrated by examples with respect to fear conditioning, an experimental procedure that has played a central role in both EPP and RDoC. We see much potential in boosting psychopathology research by combining the strengths of these two approaches.

Fear extinction learning modulates large-scale brain connectivity

Exploring the neural circuits of the extinction of conditioned fear is critical to advance our understanding of fear- and anxiety-related disorders. The field has focused on examining the role of various regions of the medial prefrontal cortex, insular cortex, hippocampus, and amygdala in conditioned fear and its extinction. The contribution of this 'fear network' to the conscious awareness of fear has recently been questioned. And as such, there is a need to examine higher/multiple cortical systems that might contribute to the conscious feeling of fear and anxiety. Herein, we studied functional connectivity patterns across the entire brain to examine the contribution of multiple networks to the acquisition of fear extinction learning and its retrieval. We conducted trial-by-trial analyses on data from 137 healthy participants who underwent a two-day fear conditioning and extinction paradigm in a functional magnetic resonance imaging (fMRI) scanner. We found that functional connectivity across a broad range of brain regions, many of which are part of the default mode, frontoparietal, and ventral attention networks, increased from early to late extinction learning only to a conditioned cue. The increased connectivity during extinction learning predicted the magnitude of extinction memory tested 24 h later. Together, these findings provide evidence supporting recent studies implicating distributed brain regions in learning, consolidation and expression of fear extinction memory in the human brain.

Failure to Identify Robust Latent Variables of Positive or Negative Valence Processing Across Units of Analysis

BACKGROUND

The heterogeneous nature of mood and anxiety disorders highlights a need for dimensionally based descriptions of psychopathology that inform better classification and treatment approaches. Following the Research Domain Criteria approach, this investigation sought to derive constructs assessing positive and negative valence domains across multiple units of analysis.

METHODS

Adults with clinically impairing mood and anxiety symptoms (N = 225) completed comprehensive assessments across several units of analysis. Self-report assessments included nine questionnaires that assess mood and anxiety symptoms and traits reflecting the negative and positive valence systems. Behavioral assessments included emotional reactivity and distress tolerance tasks, during which skin conductance and heart rate were measured. Neuroimaging assessments included fear conditioning and a reward processing task. The latent variable structure underlying these measures was explored using sparse Bayesian group factor analysis.

RESULTS

Group factor analysis identified 11 latent variables explaining 31.2% of the variance across tasks, none of which loaded across units of analysis or tasks. Instead, variance was best explained by individual latent variables for each unit of analysis within each task. Post hoc analyses 1) showed associations with small effect sizes between latent variables that were derived separately from functional magnetic resonance imaging and self-report data and 2) showed that some latent variables are not directly related to individual valence system constructs.

CONCLUSIONS

The lack of latent structure across units of analysis highlights challenges of the Research Domain Criteria approach and suggests that while dimensional analyses work well to reveal within-task features, more targeted approaches are needed to reveal latent cross-modal relationships that could illuminate psychopathology.

Anxiety and facial self-contacts: possible impact on COVID-19 transmission in dental practice

Background

The purpose was to analyse the associations between dental and trait anxiety, fear of COVID-19 and the duration and frequency of spontaneous hand-to-face contact (self-contact).

Methods

A cross-sectional design was carried out with 128 adult patients from four dental clinics in Madrid, during the confinement, from March 15 to May 15. The patients’ movements in the waiting room were monitored with Microsoft Kinect Software, also completed the Trait anxiety subscale of the STAI, the COVID-19 Fear and the S-DAI questionnaire.

Results

Associations were observed between the duration and frequency of facial, mask and eye contact with trait anxiety and dental fear was determined only by the frequency of this self-contact. Trait anxiety is associated with dental anxiety and with fear of COVID-19. Although facial self-contact is higher in women, it also rises in men as dental fear increases. Moreover, dental anxiety is a good predictor of trait anxiety and the incidence of facial self-contact.

Conclusions

Understanding the possible associations between biopsychosocial factors, such as trait anxiety, dental anxiety and self-contact is important. It may help to prevent the spread of COVID-19 in the population as well as enabling the formulation of effective interventions to improve oral health care through the implementation of dental care programmes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01564-6.

Latent cause inference during extinction learning in trauma-exposed individuals with and without PTSD

BACKGROUND

Problems in learning that sights, sounds, or situations that were once associated with danger have become safe (extinction learning) may explain why some individuals suffer prolonged psychological distress following traumatic experiences. Although simple learning models have been unable to provide a convincing account of why this learning fails, it has recently been proposed that this may be explained by individual differences in beliefs about the causal structure of the environment.

METHODS

Here, we tested two competing hypotheses as to how differences in causal inference might be related to trauma-related psychopathology, using extinction learning data collected from clinically well-characterised individuals with varying degrees of post-traumatic stress (N = 56). Model parameters describing individual differences in causal inference were related to multiple post-traumatic stress disorder (PTSD) and depression symptom dimensions via network analysis.

RESULTS

Individuals with more severe PTSD were more likely to assign observations from conditioning and extinction stages to a single underlying cause. Specifically, greater re-experiencing symptom severity was associated with a lower likelihood of inferring that multiple causes were active in the environment.

CONCLUSIONS

We interpret these results as providing evidence of a primary deficit in discriminative learning in participants with more severe PTSD. Specifically, a tendency to attribute a greater diversity of stimulus configurations to the same underlying cause resulted in greater uncertainty about stimulus-outcome associations, impeding learning both that certain stimuli were safe, and that certain stimuli were no longer dangerous. In the future, better understanding of the role of causal inference in trauma-related psychopathology may help refine cognitive therapies for these disorders.

Anxiety disorders

Anxiety disorders form the most common group of mental disorders and generally start before or in early adulthood. Core features include excessive fear and anxiety or avoidance of perceived threats that are persistent and impairing. Anxiety disorders involve dysfunction in brain circuits that respond to danger. Risk for anxiety disorders is influenced by genetic factors, environmental factors, and their epigenetic relations. Anxiety disorders are often comorbid with one another and with other mental disorders, especially depression, as well as with somatic disorders. Such comorbidity generally signifies more severe symptoms, greater clinical burden, and greater treatment difficulty. Reducing the large burden of disease from anxiety disorders in individuals and worldwide can be best achieved by timely, accurate disease detection and adequate treatment administration, scaling up of treatments when needed. Evidence-based psychotherapy (particularly cognitive behavioural therapy) and psychoactive medications (particularly serotonergic compounds) are both effective, facilitating patients' choices in therapeutic decisions. Although promising, no enduring preventive measures are available, and, along with frequent therapy resistance, clinical needs remain unaddressed. Ongoing research efforts tackle these problems, and future efforts should seek individualised, more effective approaches for treatment with precision medicine.

Fear-induced brain activations distinguish anxious and trauma-exposed brains

Translational models of fear conditioning and extinction have elucidated a core neural network involved in the learning, consolidation, and expression of conditioned fear and its extinction. Anxious or trauma-exposed brains are characterized by dysregulated neural activations within regions of this fear network. In this study, we examined how the functional MRI activations of 10 brain regions commonly activated during fear conditioning and extinction might distinguish anxious or trauma-exposed brains from controls. To achieve this, activations during four phases of a fear conditioning and extinction paradigm in 304 participants with or without a psychiatric diagnosis were studied. By training convolutional neural networks (CNNs) using task-specific brain activations, we reliably distinguished the anxious and trauma-exposed brains from controls. The performance of models decreased significantly when we trained our CNN using activations from task-irrelevant brain regions or from a brain network that is irrelevant to fear. Our results suggest that neuroimaging data analytics of task-induced brain activations within the fear network might provide novel prospects for development of brain-based psychiatric diagnosis.

Unconditioned response to an aversive stimulus as predictor of response to conditioned fear and safety: A cross-species study

Safety signals predict the non-occurrence of an aversive event, thereby inhibiting fear responses. Previous research has shown that conditioned safety learning is impaired in patients suffering from post-traumatic stress disorder (PTSD). Using a translational approach, the present study aimed to investigate whether individual responses to an aversive unconditioned stimulus (US) in rats (basic science), non-traumatized (pre-clinical) or traumatized humans (clinical) predicts their response to a conditioned fear or safety stimulus. Using three different archival datasets, the unconditioned response (UCR) to the US during fear or safety conditioning was assessed in rats, non-traumatized humans, and trauma-exposed humans. The response to learned fear (CS+; context) and safety (CS-) was measured by the modulation of the startle response (rats, traumatized humans) or skin conductance response (non-traumatized humans). Our results showed that all groups with low UCR and those with high UCR from the rodent or non-traumatized human samples displayed lower fear response to the CS- than to the CS+ . Traumatized humans with high UCR showed similarly high responses to the CS+ and CS-. While all groups showed a positive association between the UCR and CS+ response, the UCR correlated positively with the CS- response in traumatized humans only. Our findings suggest that an elevated response to aversive stimuli predicts deficits in conditioned safety memory in those at risk for trauma-related disorders and confirms that impaired safety learning could be a valid biomarker for these diseases.

Threat and safety reversal learning in social anxiety disorder - an fMRI study

Social anxiety disorder (SAD) has been linked to maladaptive forms of fear regulation, including flexibly distinguishing between learned threat and safety signals. Few studies have examined this in young, unmedicated SAD patients, including its neural basis. We aimed to characterize the neural, subjective, and autonomic correlates of reversal learning in patients with SAD and compare them to matched patients with major depressive disorder and to healthy control participants. All participants completed a threat-safety reversal learning task during functional magnetic resonance imaging. Successful threat-safety updating was associated with significant activation of primary regions of interest (anterior cingulate, insula and ventromedial prefrontal cortex), however, no significant differences were observed between them, consistent with subjective reports of task-evoked anxiety and affect. Contrary to expectations, we did not observe threat and safety reversal learning to be significantly impaired in young people with SAD.