Anxiety sensitivity correlates with two indices of right anterior insula structure in specific animal phobia

Cortical and Subcortical Brain Alterations in Specific Phobia and Its Animal and Blood-Injection-Injury Subtypes: A Mega-Analysis From the ENIGMA Anxiety Working Group

OBJECTIVE

Specific phobia is a common anxiety disorder, but the literature on associated brain structure alterations exhibits substantial gaps. The ENIGMA Anxiety Working Group examined brain structure differences between individuals with specific phobias and healthy control subjects as well as between the animal and blood-injection-injury (BII) subtypes of specific phobia. Additionally, the authors investigated associations of brain structure with symptom severity and age (youths vs. adults).

METHODS

Data sets from 31 original studies were combined to create a final sample with 1,452 participants with phobia and 2,991 healthy participants (62.7% female; ages 5-90). Imaging processing and quality control were performed using established ENIGMA protocols. Subcortical volumes as well as cortical surface area and thickness were examined in a preregistered analysis.

RESULTS

Compared with the healthy control group, the phobia group showed mostly smaller subcortical volumes, mixed surface differences, and larger cortical thickness across a substantial number of regions. The phobia subgroups also showed differences, including, as hypothesized, larger medial orbitofrontal cortex thickness in BII phobia (N=182) compared with animal phobia (N=739). All findings were driven by adult participants; no significant results were observed in children and adolescents.

CONCLUSIONS

Brain alterations associated with specific phobia exceeded those of other anxiety disorders in comparable analyses in extent and effect size and were not limited to reductions in brain structure. Moreover, phenomenological differences between phobia subgroups were reflected in diverging neural underpinnings, including brain areas related to fear processing and higher cognitive processes. The findings implicate brain structure alterations in specific phobia, although subcortical alterations in particular may also relate to broader internalizing psychopathology.

The Neurophysiology of Interoceptive Disruptions in Trauma-Exposed Populations

In the aftermath of psychological trauma, many individuals experience perturbations in interoception, a term that broadly references the ability to accurately detect body signals and integrate these signals with emotional states. These interoceptive disruptions can manifest in different ways, including blunting or amplification of sensitivity to internal physiological signals. In this chapter we review extant neurophysiological research on interoception in trauma-exposed populations, with a particular focus on the effects of chronic interpersonal trauma, such as childhood maltreatment and racial discrimination. We explore research that used different types of interoceptive assays, from self-report measures to electrophysiological and neuroimaging tools to characterize the disruptions in pain perception, interoceptive acuity, and physiological responses that may arise after a traumatic event. Finally, we discuss interventions that are designed to target interoceptive mechanisms, from exposure-based therapies to mindfulness-based practices, as well as future directions in trauma interoception research.

Threat-induced anxiety and selfishness in resource sharing: Behavioral and neural evidence

In real life, it is not unusual that we face potential threats (i.e., physical stimuli and environments that may cause harm or danger) with other individuals together, yet it remains largely unknown how threat-induced anxious feelings influence prosocial behaviors such as resource sharing. In this study, we investigated this question by combining functional magnetic resonance imaging and a novel paradigm. Together with an anonymous partner, each participant faced the possibility of receiving a 10-s noise administration, which had a low or high probability to be a threat (i.e., the intensity of noise can induce a high level of unpleasantness). Each participant first reported her/his immediate feeling of anxiety about the current situation (being threatened by the unpleasant noise), then decided how to split a number of resources (which could relieve the noise) between her/him and the partner. Behavioral results revealed that the participants showed a selfish bias in the threat conditions than in the safe conditions, and that self-reported anxiety feeling significantly predicted this bias. Functional magnetic resonance imaging results revealed that: (1) the activation level of the anterior insula was correlated with self-reported anxiety and (2) the connectivity between the anterior insula and the temporoparietal junction was sensitive to the modulating effect of anxiety on the selfish bias. These findings indicate the neural correlates of the association between threat-induced anxiety and prosocial tendencies in social interactions.

Associations between cortical thickness and anxious/depressive symptoms differ by the quality of early care

A variety of childhood experiences can lead to anxious/depressed (A/D) symptoms. The aim of the present study was to explore the brain morphological (cortical thickness and surface area) correlates of A/D symptoms and the extent to which these phenotypes vary depending on the quality of the parenting context in which children develop. Structural magnetic resonance imaging (MRI) scans were acquired on 45 children with Child Protective Services (CPS) involvement due to risk of not receiving adequate care (high-risk group) and 25 children without CPS involvement (low-risk group) (range_age = 8.08-12.14; M_age = 10.05) to assess cortical thickness (CT) and cortical surface area (SA). A/D symptoms were measured using the Child Behavioral Checklist. The association between A/D symptoms and CT, but not SA, differed by risk status such that high-risk children showed decreasing CT as A/D scores increased, whereas low-risk children showed increasing CT as A/D scores increased. This interaction was specific to CT in prefrontal, frontal, temporal, and parietal cortical regions. The groups had marginally different A/D scores, in the direction of higher risk being associated with lower A/D scores. Results suggest that CT correlates of A/D symptoms are differentially shaped by the quality of early caregiving experiences and should be distinguished between high- and low-risk children.

Brain networks under uncertainty: A coordinate-based meta-analysis of brain imaging studies

In recent years, uncertainty has been extensively studied as a core factor in anxiety models. However, it remains unclear whether there is a stable brain circuitry to cope with uncertainty. Addressing this yet open question, we first distinguish uncertainty into three different states: risky, ambiguity, and threat anticipation. Then, we performed three meta-analyses of fMRI studies to identify those regions that are commonly activated by the three domains using activation likelihood estimation (ALE). The overlapping analyses of the three ALE maps revealed major conjunctions of the risk decision making, ambiguity decision making, and the threat anticipation in specifically the right insula. Contrast analysis further confirmed this finding. In addition, different uncertainty states also have different brain networks involved. Specifically, a large number of brain regions in the frontal-parietal cortex were recruited under ambiguity state, while subcortical gray matter regions were recruited under risk decision making, and the bilateral insula were closely associated with threat anticipation. Additionally, we assessed the co-activation pattern of identified regions using meta-analytic connectivity modeling (MACM) to investigate the potential network underlying the relationship of three domains. The MACM analysis further confirmed that different uncertain states have specific brain network basis. We concluded that the right insula serves as a convergent brain region for brain regions recruited for different uncertain states, and its co-activation pattern also corresponds to the brain network of the three uncertain states. This study is a preliminary attempt to further uncover the brain circuitry of anxiety models with uncertainty at their core.

Association between cortical thickness and anxiety measures: A scoping review

Cortical thickness has been increasingly studied in the context of structural-brain-behavior associations, such as anxiety; however, the literature is scattered across methods and research fields. This scoping review aims to summarize the available data concerning the association between cortical thickness and anxiety-related measures and identify the current research gaps. Searches were conducted in PubMed, PsycINFO/PsycARTICLES, Web of Science, OpenGrey and Networked Digital Library of Theses and Dissertations, and reference lists of key studies. Two researchers independently screened the abstracts and full-text reports according to the eligibility criteria, as well as extracted and charted the data. Quantitative and descriptive syntheses were conducted. The included publications (n = 18) reported cross-sectional studies, and 17 used surface-based approaches to estimate cortical thickness. Differences in regional cortical thickness were found to be associated with different anxiety-related measures/processes. Brain regions of interest include the medial orbitofrontal cortex, the ventromedial prefrontal cortex, the insula, the temporo-parietal areas, and the anterior cingulate cortex. However, caution should be warranted when interpreting the available results, as there is high variability in the field across anxiety-related measures, distinctive anxiety disorders, and data processing conditions and analysis. More research into this association is needed, to replicate and clarify existing findings.

Neural correlates of emotional processing in panic disorder: A mini review of functional magnetic resonance imaging studies

BACKGROUND

Panic Disorder (PD) is mainly characterized by recurrent unexpected panic attacks. Although the presence of emotional functioning deficits in PD is well established, their neuronal bases are still less known. Therefore, in this review, we aim to summarize the available functional Magnetic Resonance Imaging (fMRI) studies investigating the neural correlates associated with the processing of facial emotional expressions in patients with PD.

METHODS

A comprehensive search on PubMed was performed and 10 fMRI studies meeting our inclusion criteria were included in this review.

RESULTS

The majority of the studies reported selective deficits in key brain regions within the prefronto-limbic network in PD patients. Specifically, a mixed picture of hyperactivation and hypoactivation patterns were observed in limbic regions, including the amygdala and the anterior cingulate cortex (ACC), as well as in areas within the prefrontal cortex (PFC), either during negative or positive valenced stimuli, as compared to healthy controls (HC) or other anxiety disorders.

LIMITATIONS

The limited number of studies and the clinical and methodological heterogeneity make it difficult to draw definite conclusions on the neural mechanism of emotional processing associated with PD.

CONCLUSION

Although the results of the available evidence suggest the presence of selective dysfunctions in regions within the cortico-limbic network in PD patients during processing of emotional stimuli, the direction of these abnormalities is still unclear. Therefore, future larger and more homogeneous studies are needed to elucidate the neural mechanisms underpinning the emotional processing dysfunctions often observed in PD patients.

Dysfunction of Resting-State Functional Connectivity of Amygdala Subregions in Drug-Naïve Patients With Generalized Anxiety Disorder

Objective: Although previous studies have reported on disrupted amygdala subregional functional connectivity in generalized anxiety disorder (GAD), most of these studies were conducted in GAD patients with comorbidities or with drug treatment. Besides, whether/how the amygdala subregional functional networks were associated with state and trait anxiety is still largely unknown. Methods: Resting-state functional connectivity of amygdala subregions, including basolateral amygdala (BLA) and centromedial amygdala (CMA) as seed, were mapped and compared between 37 drug-naïve, non-comorbidity GAD patients and 31 age- and sex-matched healthy controls (HCs). Relationships between amygdala subregional network dysfunctions and state/trait anxiety were examined using partial correlation analyses. Results: Relative to HCs, GAD patients showed weaker functional connectivity of the left BLA with anterior cingulate/medial prefrontal cortices. Significantly increased functional connectivity of right BLA and CMA with superior temporal gyrus and insula were also identified in GAD patients. Furthermore, these functional connectivities showed correlations with state and trait anxiety scores. Conclusions: These findings revealed abnormal functional coupling of amygdala subregions in GAD patients with regions involved in fear processing and emotion regulation, including anterior cingulate/medial prefrontal cortex and superior temporal gyrus, which provide the unique biological markers for GAD and facilitating the future accurate clinical diagnosis and target treatment.

Spider Phobia: Neural Networks Informing Diagnosis and (Virtual/Augmented Reality-Based) Cognitive Behavioral Psychotherapy-A Narrative Review

Recent fMRI studies on specific animal phobias, particularly spider phobia (arachnophobia), have identified a large variety of specific brain regions involved in normal and disturbed fear processing. Both functional and structural brain abnormalities have been identified among phobic patients. Current research suggests that both conscious and subconscious fear processing play a crucial role in phobic disorders. Cognitive behavioral therapy has been identified as an effective treatment for specific phobias and has been associated with neuroplastic effects which can be evaluated using current neuroimaging techniques. Recent research suggests that new approaches using virtual (VR) or augmented reality (AR) tend to be similarly effective as traditional "in vivo" therapy methods and could expand treatment options for different medical or individual scenarios. This narrative review elaborates on neural structures and particularities of arachnophobia. Current treatment options are discussed and future research questions are highlighted.

Altered Interoceptive Perception and the Effects of Interoceptive Analgesia in Musculoskeletal, Primary, and Neuropathic Chronic Pain Conditions

Chronic pain (CP) severely disrupts the daily life of millions. Interoception (i.e., sensing the physiological condition of the body) plays a pivotal role in the aetiology and maintenance of CP. As pain is inherently an interoceptive signal, interoceptive frameworks provide important, but underutilized, approaches to this condition. Here we first investigated three facets of interoceptive perception in CP, compared with pain-free controls. We then introduce a novel interoceptive treatment and demonstrate its capacity to reduce pain severity in CP, potentially providing complementary analgesic treatments. Study 1 measured interoceptive accuracy, confidence and sensibility in patients (N = 60) with primary, secondary musculoskeletal, and neuropathic CP. Compared with matched controls, CP participants exhibited significantly lower interoceptive accuracy and interoceptive confidence. Pain severity was predicted positively by interoceptive accuracy, anxiety and depression, and negatively by interoceptive confidence. Study 2 tested a promising new interoceptive treatment for CP, in a single-blind between-subjects design (N = 51) with primary, secondary musculoskeletal, and neuropathic CP patients. The treatment specifically activates the C-Tactile system, by means of controlled stimulation of interoceptive unmyelinated afferents, at 3 cm/s with a force of 2.5 mN. This treatment led to significant pain reduction (mean 23%) in the CP treatment group after only 11 min, while CP controls who received comparable but non-interoceptive stimulation reported no change in pain intensity. These studies highlight the importance of interoceptive approaches to CP and demonstrate the potential of this novel method of C-Tactile stimulation to provide complementary analgesic treatments.

Self-injuring adolescent girls exhibit insular cortex volumetric abnormalities that are similar to those seen in adults with borderline personality disorder

Self-inflicted injury (SII) in adolescence is a serious public health concern that portends prospective vulnerability to internalizing and externalizing psychopathology, borderline personality development, suicide attempts, and suicide. To date, however, our understanding of neurobiological vulnerabilities to SII is limited. Behaviorally, affect dysregulation is common among those who self-injure. This suggests ineffective cortical modulation of emotion, as observed among adults with borderline personality disorder. In borderline samples, structural and functional abnormalities are observed in several frontal regions that subserve emotion regulation (e.g., anterior cingulate, insula, dorsolateral prefrontal cortex). However, no volumetric analyses of cortical brain regions have been conducted among self-injuring adolescents. We used voxel-based morphometry to compare cortical gray matter volumes between self-injuring adolescent girls, ages 13-19 years (n = 20), and controls (n = 20). Whole-brain analyses revealed reduced gray matter volumes among self-injurers in the insular cortex bilaterally, and in the right inferior frontal gyrus, an adjacent neural structure also implicated in emotion and self-regulation. Insular and inferior frontal gyrus gray matter volumes correlated inversely with self-reported emotion dysregulation, over-and-above effects of psychopathology. Findings are consistent with an emotion dysregulation construal of SII, and indicate structural abnormalities in some but not all cortical brain regions implicated in borderline personality disorder among adults.

Short Version Dental Anxiety Inventory Score May Predict the Response in the Insular Cortex to Stimuli Mimicking Dental Treatment

Background: Dental anxiety is a common reason for avoiding dental visits and is associated with poor dental status. The short version of Dental Anxiety Inventory (SDAxI) is an easy-to-use, multi-faceted questionnaire for assessing the level of trait dental anxiety. However, there was no neurophysiological data indicating if its score associates with the state anxiety when an individual is under real/mock dental environment. We hypothesized that there exists such an association. Materials and Methods: Twenty systemic healthy adults with dental attendance experience and self-claimed free of dental phobia were recruited in this cross-sectional study, with their dental anxiety level assessed by SDAxI. Functional magnetic resonance imaging recorded their brain signals in response to audiovisual footages resembling dental scaler or turbine in action. After the brain imaging, they gave fear ratings to the footages in visual analog scale (VAS). Results: Participants' SDAxI scores positively correlated with their responses in the insular cortex (r² = 0.388-0.445, P < 0.005). Their SDAxI scores also positively correlated with their fear ratings of the footages (r ² = 0.415-0.555, P < 0.005). Discussion: Our findings indicated a possible neurobiological relevance of SDAxI, and reinforced its neurobiological validity in assessing dental anxiety level of dental attenders.

On a continuum to anxiety disorders: Adolescents at parental risk for anxiety show smaller rostral anterior cingulate cortex and insula thickness

BACKGROUND

Having a parent with an anxiety disorder increases the risk of anxiety symptoms and anxiety disorders during the lifespan. Moreover, childhood and adolescence anxiety disorders and symptoms have been linked to a range of brain structure abnormalities. However, to date, no study has investigated brain anatomy in adolescents at high risk based on parental anxiety disorders and in adolescents with an anxiety disorder but without any treatment or therapy.

METHODS

Anatomical images from magnetic resonance imaging of 68 adolescents with anxiety disorders without any treatment (N = 20), at risk for anxiety because of their parents' anxiety disorders (N = 21), and comparison youths (N = 27), were analyzed using Freesurfer.

RESULTS

Compared to comparison group, smaller cortical thickness of the rostral anterior cingulate cortex and of the insula was observed in anxious and at-risk groups; smaller amygdala volume was observed in the anxious group only.

LIMITATIONS

The age range studied is large (10 to 17 years old). Moreover, this study is cross-sectional. Since adolescence is one of the biggest periods of cerebral reorganization, longitudinal follow-up of these youths would be necessary.

CONCLUSIONS

Smaller rostral anterior cingulate cortex and insula cortical thickness appear to be cerebral markers of the risk of developing an anxiety disorder in adolescence. The reduction of the amygdala volume seems to be linked to the onset of the disorder.

Feel the Time. Time Perception as a Function of Interoceptive Processing

The nature of time is rooted in our body. Constellations of impulses arising from the flesh constantly create our interoceptive perception and, in turn, the unfolding of these perceptions defines human awareness of time. This study explored the connection between time perception and interoception and proposes the Interoceptive Buffer saturation (IBs) index. IBs evaluates subjects’ ability to process salient stimuli from the body by measuring subjective distortions of interoceptive time perception, i.e., the estimated duration of tactile interoceptive stimulations. Thirty female healthy subjects were recruited through consecutive sampling and assessed for common variables related to interoceptive alterations: depressive symptoms (Beck Depression Inventory, BDI-II), eating disorders (EDI-3) risk, and anxiety levels (State Trait Anxiety Inventory, STAI). Interoceptive cardiac accuracy (IAc) was assessed as well. Subjects performed verbal time estimation of interoceptive stimuli (IBs) delivered using a specifically designed interoceptive tactile stimulator, as well as verbal time estimation of visual and auditory stimuli. Results showed that IBs index positively correlated with IAc, and negatively with EDI-3 Drive for Thinness (DT) risk subscale. Moreover, IBs index was positively predicted by IAc, and negatively predicted by DT and somatic factors of depression. Our results suggest that underestimations in interoceptive time perception are connected to different psychological conditions characterized by a diminished processing of high salience stimuli from the body. Conversely, overestimations of the duration of interoceptive stimuli appear to be function of subjects’ ability to correctly perceive their own bodily information. Evidence supported IBs index, fostering the concept of interoceptive treatments for clinical purposes.

Imaging and Genetic Approaches to Inform Biomarkers for Anxiety Disorders, Obsessive-Compulsive Disorders, and PSTD

Anxiety disorders are the most common mental health problem in the world and also claim the highest health care cost among various neuropsychiatric disorders. Anxiety disorders have a chronic and recurrent course and cause significantly negative impacts on patients' social, personal, and occupational functioning as well as quality of life. Despite their high prevalence rates, anxiety disorders have often been under-diagnosed or misdiagnosed, and consequently under-treated. Even with the correct diagnosis, anxiety disorders are known to be difficult to treat successfully. In order to implement better strategies in diagnosis, prognosis, treatment decision, and early prevention for anxiety disorders, tremendous efforts have been put into studies using genetic and neuroimaging techniques to advance our understandings of the underlying biological mechanisms. In addition to anxiety disorders including panic disorder, generalised anxiety disorder (GAD), specific phobias, social anxiety disorders (SAD), due to overlapping symptom dimensions, obsessive-compulsive disorder (OCD), and post-traumatic stress disorder (PTSD) (which were removed from the anxiety disorder category in DSM-5 to become separate categories) are also included for review of relevant genetic and neuroimaging findings. Although the number of genetic or neuroimaging studies focusing on anxiety disorders is relatively small compare to other psychiatric disorders such as psychotic disorders or mood disorders, various structural abnormalities in the grey or white matter, functional alterations of activity during resting-state or task conditions, molecular changes of neurotransmitter receptors or transporters, and genetic associations have all been reported. With continuing effort, further genetic and neuroimaging research may potentially lead to clinically useful biomarkers for the prevention, diagnosis, and management of these disorders.

Neural correlates of individual differences in anxiety sensitivity: an fMRI study using semantic priming

Individuals with high anxiety sensitivity (AS) have an increased risk of developing anxiety disorders and are more biased in how they process fear-related stimuli. This study investigates the neural correlates of fear-related words and word associations in high- and low-AS individuals. We used a semantic priming paradigm during functional magnetic resonance imaging in which three types of target words (fear symptoms, e.g. 'dizziness'; neutral, e.g. 'drink'; and pseudowords, e.g. 'salkom') were preceded by two types of prime words (fear-triggers, e.g. 'elevator'; and neutral, e.g. 'bottle'). Subjects with high AS rated fear-symptom words (vs neutral words) as more unpleasant than low-AS individuals; they also related these words more strongly to fear-triggers and showed prolonged reaction times. During the processing of fear-symptom words, greater activation in the left anterior insula was observed in high-AS subjects than in low-AS subjects. Lower activation in the left inferior frontal gyrus, angular gyrus, fusiform gyrus and bilateral amygdalae was found in high-AS subjects when fear-symptom words were preceded by fear-trigger words. The findings suggest that cognitive biases and the anterior insula play a crucial role in high-AS individuals. Furthermore, semantic processes may contribute to high AS and the risk of developing anxiety disorders.

Emotional Intelligence Partially Mediates the Association between Anxiety Sensitivity and Anxiety Symptoms1,2

Anxiety Sensitivity (AS), the propensity to fear the somatic, mental, and social consequences of anxiety, is associated with an elevated risk of developing anxiety disorders. It was hypothesized that Emotional Intelligence (EI) might serve as a mediating variable between AS and anxiety symptom expression. Sixty-one healthy adults (30 men, 31 women; M age = 30.4 yr., SD = 8.0), recruited through posted advertisements, completed the Anxiety Sensitivity Index (ASI) and the ANX subscale of the Personality Assessment Inventory (PAI), as well as three assessments of EI, including two indices of the Ability model of EI (MSCEIT; SREIS), and one index of the Trait model of EI (i.e., Bar-On EQ-i). Partial mediation between AS and ANX was found for the EQ-i but not for the MSCEIT or SREIS, as determined by the bootstrap method of mediation analysis. The association between AS and anxiety symptoms was partly explained through its effects on the intervening variable of Trait EI, and points to the possibility that interventions improving Trait EI may be useful in reducing the expression of anxiety symptoms in people with high AS.

ADULT ANXIETY DISORDERS IN RELATION TO TRAIT ANXIETY AND PERCEIVED STRESS IN CHILDHOOD

It is well established that objective early life stressors increase risk for anxiety disorders and that environmental stressors interact with dispositional factors such as trait anxiety. There is less information on how subjective perception of stress during childhood relates to later clinical anxiety. This study tested whether childhood perceived stress and trait anxiety were independently and interactively associated with adult anxiety disorders. Forty-seven adults diagnosed with anxiety disorders (M age = 34 yr., SD = 11) and 29 healthy participants (M = 33 yr., SD = 13) completed the adult Perceived Stress Scale, the State-Trait Anxiety Inventory, and the Global Perceived Early Life Events Scale as a measure of perceived stress during childhood. In a logistic regression model, high childhood perceived stress (β = 0.64) and trait anxiety (β = 0.11) were associated with significantly greater odds of adult anxiety disorder. The association between childhood perceived stress and adult anxiety remained significant when controlling for adult perceived stress. These findings suggest that children's perception of stress in their daily lives may be an important target of intervention to prevent the progression of stress into clinically significant anxiety.

Neural correlates of anxiety sensitivity in panic disorder: A functional magnetic resonance imaging study

Panic disorder has been associated with dysfunctional neuropsychological dimensions, including anxiety sensitivity. Brain-imaging studies of the neural correlates of emotional processing have identified a network of structures that constitute the neural circuitry for emotions. The anterior cingulate cortex (ACC), medial prefrontal cortex (mPFC) and insula, which are part of this network, are also involved in the processing of threat-related stimuli. The aim of the study was to investigate if neural activity in response to emotional stimuli in the cortico-limbic network is associated to anxiety sensitivity in panic disorder. In a sample of 18 outpatients with panic disorder, we studied neural correlates of implicit emotional processing of facial affect expressions with a face-matching paradigm; correlational analyses were performed between brain activations and anxiety sensitivity. The correlational analyses performed showed a positive correlation between anxiety sensitivity and brain activity during emotional processing in regions encompassing the PFC, ACC and insula. Our data seem to confirm that anxiety sensitivity is an important component of panic disorder. Accordingly, the neural underpinnings of anxiety sensitivity could be an interesting focus for treatment and further research.

Neural circuits in anxiety and stress disorders: a focused review

Anxiety and stress disorders are among the most prevalent neuropsychiatric disorders. In recent years, multiple studies have examined brain regions and networks involved in anxiety symptomatology in an effort to better understand the mechanisms involved and to develop more effective treatments. However, much remains unknown regarding the specific abnormalities and interactions between networks of regions underlying anxiety disorder presentations. We examined recent neuroimaging literature that aims to identify neural mechanisms underlying anxiety, searching for patterns of neural dysfunction that might be specific to different anxiety disorder categories. Across different anxiety and stress disorders, patterns of hyperactivation in emotion-generating regions and hypoactivation in prefrontal/regulatory regions are common in the literature. Interestingly, evidence of differential patterns is also emerging, such that within a spectrum of disorders ranging from more fear-based to more anxiety-based, greater involvement of emotion-generating regions is reported in panic disorder and specific phobia, and greater involvement of prefrontal regions is reported in generalized anxiety disorder and posttraumatic stress disorder. We summarize the pertinent literature and suggest areas for continued investigation.

Cortical thinning of the right anterior cingulate cortex in spider phobia: a magnetic resonance imaging and spectroscopy study

There a lack of consistent neuroimaging data on specific phobia (SP) and a need to assess volumetric and metabolic differences in structures implicated in this condition. The aim of this study is investigate possible metabolic (via (1)H MRS) and cortical thickness abnormalities in spider-phobic patients compared to healthy volunteers. Participants were recruited via public advertisement and underwent clinical evaluations and MRI scans. The study started in 2010 and the investigators involved were not blind in respect to patient groupings. The study was conducted at the Ribeirão Preto Medical School University Hospital of the University of São Paulo, Brazil. Patients with spider phobia (n=19) were matched to 17 healthy volunteers with respect to age, education and socio-economic status. The spider SP group fulfilled the diagnostic criteria for spider phobia according to the Structured Clinical Interview for DSM-IV. None of the participants had a history of neurological, psychiatric or other relevant organic diseases, use of prescribed psychotropic medication or substance abuse. All imaging and spectroscopy data were collected with a 3 T MRI scanner equipped with 25 mT gradient coils in 30-minute scans. The Freesurfer image analysis package and LC Model software were used to analyze data. The hypothesis being tested was formulated before the data collection (neural correlates of SP would include the amygdala, insula, anterior cingulate gyrus and others). The results indicated the absence of metabolic alterations, but thinning of the right anterior cingulate cortex (ACC) in the SP group when compared to the healthy control group (mean cortical thickness±SD: SP=2.11±0.45 mm; HC=2.16±0.42 mm; t (34)=3.19, p=0.001 [-35.45, 71.00, -23.82]). In spectroscopy, the ratios between N-acetylaspartate and creatine and choline levels were measured. No significant effect or correlation was found between MRS metabolites and scores in the Spider Phobia Questionnaire and Beck Anxiety Inventory (p>0.05). The ACC is known to be related to the cognitive processing of fear and anxiety and to be linked with the conditioning circuit. The MRS findings are preliminary and need more studies. The finding of reduced ACC thickness in SP is in agreement with evidence from previous functional neuroimaging studies and highlights the importance of this brain area in the pathophysiology of SP.

Age-related reduced prefrontal-amygdala structural connectivity is associated with lower trait anxiety

OBJECTIVE

A current neuroanatomical model of anxiety posits that greater structural connectivity between the amygdala and ventral prefrontal cortex (vPFC) facilitates regulatory control over the amygdala and helps reduce anxiety. However, some neuroimaging studies have reported contradictory findings, demonstrating a positive rather than negative association between trait anxiety and amygdala-vPFC white matter integrity. To help reconcile these findings, we tested the regulatory hypothesis of anxiety circuitry using aging as a model of white matter decline in the amygdala-vPFC pathway.

METHODS

We used probabilistic tractography to trace connections between the amygdala and vPFC in 21 younger, 18 middle-aged, and 15 healthy older adults. The resulting tract estimates were used to extract 3 indices of white-matter integrity: fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD). The relationship between these amygdala-vPFC structural connectivity measures and age and State-Trait Anxiety Inventory (STAI) scores were assessed.

RESULTS

The tractography results revealed age-related decline in the FA (p = .005) and radial diffusivity (p = .002) of the amygdala-vPFC pathway. Contrary to the regulatory hypothesis, we found a positive rather than negative association between trait anxiety and right amygdala-vPFC FA (p = .01).

CONCLUSION

These findings argue against the notion that greater amygdala-vPFC structural integrity facilitates better anxiety outcomes in healthy adults. Instead, our results suggest that white matter degeneration in this network relates to lower anxiety in older adults.

"The mind is its own place": amelioration of claustrophobia in semantic dementia

Phobias are among the few intensely fearful experiences we regularly have in our everyday lives, yet the brain basis of phobic responses remains incompletely understood. Here we describe the case of a 71-year-old patient with a typical clinicoanatomical syndrome of semantic dementia led by selective (predominantly right-sided) temporal lobe atrophy, who showed striking amelioration of previously disabling claustrophobia following onset of her cognitive syndrome. We interpret our patient's newfound fearlessness as an interaction of damaged limbic and autonomic responsivity with loss of the cognitive meaning of previously threatening situations. This case has implications for our understanding of brain network disintegration in semantic dementia and the neurocognitive basis of phobias more generally.

Peril and pleasure: an rdoc-inspired examination of threat responses and reward processing in anxiety and depression

As a step toward addressing limitations in the current psychiatric diagnostic system, the National Institute of Mental Health recently developed the Research Domain Criteria (RDoC) to stimulate integrative research-spanning self-report, behavior, neural circuitry, and molecular/genetic mechanisms-on core psychological processes implicated in mental illness. Here, we use the RDoC conceptualization to review research on threat responses, reward processing, and their interaction. The first section of the manuscript highlights the pivotal role of exaggerated threat responses-mediated by circuits connecting the frontal cortex, amygdala, and midbrain-in anxiety, and reviews data indicating that genotypic variation in the serotonin system is associated with hyperactivity in this circuitry, which elevates the risk for anxiety and mood disorders. In the second section, we describe mounting evidence linking anhedonic behavior to deficits in psychological functions that rely heavily on dopamine signaling, especially cost/benefit decision making and reward learning. The third section covers recent studies that document negative effects of acute threats and chronic stress on reward responses in humans. The mechanisms underlying such effects are unclear, but the fourth section reviews new optogenetic data in rodents indicating that GABAergic inhibition of midbrain dopamine neurons, driven by activation of the habenula, may play a fundamental role in stress-induced anhedonia. In addition to its basic scientific value, a better understanding of interactions between the neural systems that mediate threat and reward responses may offer relief from the burdensome condition of anxious depression.

A neural model of mechanisms of empathy deficits in narcissism

From a multidimensional perspective, empathy is a process that includes affective sharing and imagining and understanding the emotions of others. The primary brain structures involved in mediating the components of empathy are the anterior insula (AI), the anterior cingulate cortex (ACC), and specific regions of the medial prefrontal cortex (MPFC). The AI and ACC are the main nodes in the salience network (SN), which selects and coordinates the information flow from the intero- and exteroreceptors. AI might play a role as a crucial hub – a dynamic switch between 2 separate networks of cognitive processing: the central executive network (CEN), which is concerned with effective task execution, and the default mode network (DMN), which is involved with self-reflective processes. Given various classifications, a deficit in empathy may be considered a central dysfunctional trait in narcissism. A recent fMRI study suggests that deficit in empathy is due to a dysfunction in the right AI. Based on the acquired data, we propose a theoretical model of imbalanced SN functioning in narcissism in which the dysfunctional AI hub is responsible for constant DMN activation, which, in turn, centers one’s attention on the self. This might hinder the ability to affectively share and understand the emotions of others. This review paper on neural mechanisms of empathy deficits in narcissism aims to inspire and direct future research in this area.

Age-related changes in insula cortical thickness and impulsivity: significance for emotional development and decision-making

Insula function has been associated with emotional regulation, adjusting to changing outcomes under risk, reward and loss anticipation, discounting of future rewards, and self-rated impulsivity. The role of the insula in these processes may be fundamentally related to prospective thinking, a trait that increases with age. There is evidence that insular cortical thickness shows age related decreases that parallel age related increases in future orientation and planning. We tested the hypothesis that nonplanning decreases with age and that insula thickness is related to both age and nonplanning impulsivity. Fifty-nine male and female participants, ranging in age from 10 to 22 years old, underwent structural magnetic resonance imaging (MRI) procedures and were assessed using the Barratt Impulsiveness Scale (BIS). We observed that anterior insula thickness and nonplanning impulsivity show an inverse relationship with age and that there is a significant positive linear relationship between anterior insula thickness and nonplanning.

Alpha activity in the insula accompanies the urge to neutralize in sub-clinical obsessive-compulsive participants

Background and aims The behavioural addiction model of obsessive-compulsive disorder (OCD) proposes that as compulsions successfully reduce obsession-provoked anxiety in the early stages of the disorder, their performance is rewarding and therefore potentially addictive. According to this theory, the urge to perform a compulsion or neutralization resembles craving in addiction, and ventral fronto-striatal reward circuitry is activated during compulsive or neutralizing behaviour, resembling substance addiction disorders. The current study used EEG source localisation to test this hypothesis by examining brain activity accompanying the urge to neutralize and covert neutralization. Methods Two groups of non-clinical participants (15 Low-OC, 15 High-OC) performed a task in which the urge to neutralize was induced by supplying participants with an obsessive-compulsive-like thought. Source localised EEG activity was compared between a negative condition with high urge to neutralize, and a positive condition with low urge to neutralize, and correlations between brain activity and self-reported urge to neutralize were examined. Results High-OC participants reported a significantly greater urge to neutralize than Low-OC participants, and the majority of participants reported performing covert neutralization during the experiment. Between-condition comparisons in the High-OC group revealed significantly greater alpha activity in the insula and vlPFC in the negative than the positive condition, which was significantly correlated with both urge to neutralize and later decrease in negative affect. Conclusions The current results support the proposal that the urge to neutralize in OCD is neurally similar to craving in substance addiction, in agreement with the behavioural addiction model of OCD.

Correlating anterior insula gray matter volume changes in young people with clinical and neurocognitive outcomes: an MRI study

BACKGROUND

The anterior insula cortex is considered to be both the structural and functional link between experience, affect, and behaviour. Magnetic resonance imaging (MRI) studies have shown changes in anterior insula gray matter volume (GMV) in psychosis, bipolar, depression and anxiety disorders in older patients, but few studies have investigated insula GMV changes in young people. This study examined the relationship between anterior insula GMV, clinical symptom severity and neuropsychological performance in a heterogeneous cohort of young people presenting for mental health care.

METHODS

Participants with a primary diagnosis of depression (n = 43), bipolar disorder (n = 38), psychosis (n = 32), anxiety disorder (n = 12) or healthy controls (n = 39) underwent structural MRI scanning, and volumetric segmentation of the bilateral anterior insula cortex was performed using the FreeSurfer application. Statistical analysis examined the linear and quadratic correlations between anterior insula GMV and participants' performance in a battery of clinical and neuropsychological assessments.

RESULTS

Compared to healthy participants, patients had significantly reduced GMV in the left anterior insula (t = 2.05, p = .042) which correlated with reduced performance on a neuropsychological task of attentional set-shifting (ρ = .32, p = .016). Changes in right anterior insula GMV was correlated with increased symptom severity (r = .29, p = .006) and more positive symptoms (r = .32, p = .002).

CONCLUSIONS

By using the novel approach of examining a heterogeneous cohort of young depression, anxiety, bipolar and psychosis patients together, this study has demonstrated that insula GMV changes are associated with neurocognitive deficits and clinical symptoms in such young patients.

Regional brain differences in cortical thickness, surface area and subcortical volume in individuals with Williams syndrome

Williams syndrome (WS) is a rare genetic neurodevelopmental disorder characterized by increased non-social anxiety, sensitivity to sounds and hypersociability. Previous studies have reported contradictory findings with regard to regional brain variation in WS, relying on only one type of morphological measure (usually volume) in each study. The present study aims to contribute to this body of literature and perhaps elucidate some of these discrepancies by examining concurrent measures of cortical thickness, surface area and subcortical volume between WS subjects and typically-developing (TD) controls. High resolution MRI scans were obtained on 31 WS subjects and 50 typically developing control subjects. We derived quantitative regional estimates of cortical thickness, cortical surface area, and subcortical volume using FreeSurfer software. We evaluated between-group ROI differences while controlling for total intracranial volume. In post-hoc exploratory analyses within the WS group, we tested for correlations between regional brain variation and Beck Anxiety Inventory scores. Consistent with our hypothesis, we detected complex patterns of between-group cortical variation, which included lower surface area in combination with greater thickness in the following cortical regions: post central gyrus, cuneus, lateral orbitofrontal cortex and lingual gyrus. Additional cortical regions showed between-group differences in one (but not both) morphological measures. Subcortical volume was lower in the basal ganglia and the hippocampus in WS versus TD controls. Exploratory correlations revealed that anxiety scores were negatively correlated with gray matter surface area in insula, OFC, rostral middle frontal, superior temporal and lingual gyrus. Our results were consistent with previous reports showing structural alterations in regions supporting the socio-affective and visuospatial impairments in WS. However, we also were able to effectively capture novel and complex patterns of cortical differences using both surface area and thickness. In addition, correlation results implicate specific brain regions in levels of anxiety in WS, consistent with previous reports investigating general anxiety disorders in the general population.

Neural correlates of anxiety sensitivity during masked presentation of affective faces

BACKGROUND

Anxiety Sensitivity (AS), the tendency to fear the thoughts, symptoms, and social consequences associated with the experience of anxiety, is associated with increased risk for developing anxiety disorders. Some evidence suggests that higher scores on the Anxiety Sensitivity Index (ASI), a measure of the AS construct, are associated with activation of the anterior insular cortex during overt emotion perception. Although the ASI provides subscale scores measuring Physical, Mental Incapacitation, and Social Concerns of AS, no study has examined the relationship between these factors and regional brain activation during affect processing. We hypothesized that insular responses to fear-related stimuli would be primarily related to the Physical Concerns subscale of the ASI, particularly for a sample of subjects with specific phobias.

METHODS

Adult healthy controls (HC; n = 22) and individuals with specific phobia, small animal subtype (SAP; n = 17), completed the ASI and underwent functional magnetic resonance imaging while engaged in a backward-masked affect perception task that presents emotional facial stimuli below the threshold of conscious perception.

RESULTS

Groups did not differ in ASI, state or trait anxiety scores, or insula activation. Total ASI scores were positively correlated with activation in the right middle/anterior insula for the combined sample and for the HC and SAP groups separately. Multiple regression analysis revealed that the relationship between AS and insular activation was primarily accounted for by Physical Concerns only.

CONCLUSIONS

Findings support the hypothesized role of the right anterior insula in the visceral/interoceptive aspects of AS, even in response to masked affective stimuli.