Subclinical Agoraphobia Symptoms and Regional Brain Volumes in Non-clinical Subjects: Between Compensation and Resilience?

Emotional intelligence mediates the association between middle temporal gyrus gray matter volume and social anxiety in late adolescence

As a common mental health problem, social anxiety refers to the fear and avoidance of interacting in social or performance situations, which plays a crucial role in many health and social problems. Although a growing body of studies has explored the neuroanatomical alterations related to social anxiety in clinical patients, far fewer have examined the association between social anxiety and brain morphology in the general population, which may help us understand the neural underpinnings of social anxiety more comprehensively. Here, utilizing a voxel-based morphometry approach via structural magnetic resonance imaging, we investigated brain gray matter correlates of social anxiety in 231 recent graduates of the same high school grade. We found that social anxiety was positively associated with gray matter volume in the right middle temporal gyrus (MTG), which is a core brain area for cognitive processing of emotions and feelings. Critically, emotional intelligence mediated the impact of right MTG volume on social anxiety. Notably, our results persisted even when controlling for the effects of general anxiety and depression. Altogether, our research reveals right MTG gray matter volume as a neurostructural correlate of social anxiety in a general sample of adolescents and suggests a potential indirect effect of emotional intelligence on the association between gray matter volume and social anxiety.

Brain Structure and Subclinical Symptoms: A Dimensional Perspective of Psychopathology in the Depression and Anxiety Spectrum

Human psychopathology is the result of complex and subtle neurobiological alterations. Categorial DSM or ICD diagnoses do not allow a biologically founded and differentiated description of these diverse processes across a spectrum or continuum, emphasising the need for a scientific and clinical paradigm shift towards a dimensional psychiatric nosology. The subclinical part of the spectrum is, however, of special interest for early detection of mental disorders. We review the current evidence of brain structural correlates (grey matter volume, cortical thickness, and gyrification) in non-clinical (psychiatrically healthy) subjects with minor depressive and anxiety symptoms. We identified 16 studies in the depressive spectrum and 20 studies in the anxiety spectrum. These studies show effects associated with subclinical symptoms in the hippocampus, anterior cingulate cortex, and anterior insula similar to major depression and changes in amygdala similar to anxiety disorders. Precuneus and temporal areas as parts of the default mode network were affected specifically in the subclinical studies. We derive several methodical considerations crucial to investigations of brain structural correlates of minor psycho(patho)logical symptoms in healthy participants. And we discuss neurobiological overlaps with findings in patients as well as distinct findings, e.g. in areas involved in the default mode network. These results might lead to more insight into the early pathogenesis of clinical significant depression or anxiety and need to be enhanced by multi-centre and longitudinal studies.

Association between Uncinate Fasciculus Integrity and Agoraphobia Symptoms in Female Patients with Panic Disorder

Objective

Although neural correlates of sub-clinical agoraphobia (AG) symptoms have been previously suggested, only a few studies evaluating structural changes of the brain have been conducted in agoraphobic patients with panic disorder (PD). We investigated and compared white matter (WM) micro-structural alterations between PD patients with AG (PD ＋ AG) and those without AG (PD − AG).

Methods

Our study included 56 female PD patients, of which 25 were diagnosed with AG and 31 were diagnosed without AG. Diffusion tensor imaging was performed to investigate micro-structural changes in the WM tracts related to fronto-temporo-occipital areas (uncinate fasciculus, cingulum bundle, inferior longitudinal/fronto-occipital fasciculus, fornix column and body, and fornix/stria terminalis). All participants were subjected to the Anxiety Sensitivity Inventory-Revised (ASI-R), Beck Depression Inventory-II (BDI-II), and Albany Panic and Phobia questionnaires.

Results

The fractional anisotropy values of the right uncinate fasciculus in PD ＋ AG were significantly lower than that of PD − AG and showed significant correlations with BDI-II and ASI-R total scores. Mean diffusivity and radial diffusivity values of the right uncinate fasciculus were significantly higher in PD ＋ AG as compared to PD − AG.

Conclusion

Our findings suggest that the uncinate fasciculus may be associated with AG symptoms in PD, possibly through demyelination. Our findings may contribute to the neurobiological evidence regarding the association between AG and WM structural changes in PD.

Spontaneous brain state oscillation is associated with self-reported anxiety in a non-clinical sample

The anti-correlation relationship between the default-mode network (DMN) and task-positive network (TPN) may provide valuable information on cognitive functions and mental disorders. Moreover, maintaining a specific brain state and efficaciously switching between different states are considered important for self-regulation and adaptation to changing environments. However, it is currently unclear whether competitions between the DMN and TPN are associated with negative affect (here, anxiety and depression) in non-clinical samples. We measured the average dwell time of DMN dominance over the TPN (i.e., the average state duration before transition to another state, indicating persistent DMN dominance) with a sample of 302 non-clinical young adults. Subsequently, we explored individual differences in this persistent DMN dominance by examining its correlations with subjective depression and anxiety feelings. Moreover, we linked state transition between DMN/TPN dominance with right fronto-insular cortex (RFIC) blood oxygen-level dependent signal variability. We found that the average dwell time of DMN dominance was positively associated with self-reported anxiety. Furthermore, state transition between DMN or TPN dominance was positively linked to RFIC activity. These findings highlight the importance of investigating the complex and dynamic reciprocal inhibition patterns of the DMN and TPN and the important role of the RFIC in the association between these networks.

Interfacing neural constructs with the Hierarchical Taxonomy of Psychopathology: 'Why' and 'how'

The Hierarchical Taxonomy of Psychopathology (HiTOP) represents a crucial step forward in the empirical refinement of psychiatric nosology. Although grounded in factor analyses of clinical symptoms and affiliated traits, HiTOP encourages research using measures of other types, including neural-system variables, to clarify coherent processes contributing to the hierarchical structure of psychopathology. However, systematic strategies for interfacing HiTOP dimensions with neural-system variables have not been put forth. We discuss reasons for considering neurobiological systems in relation to HiTOP (i.e. 'why') and propose alternative strategies that might be used to develop an interface between HiTOP and neurobiology (i.e. 'how'). In particular, we highlight potential advantages and limitations of establishing this interface through reference to (i) HiTOP dimensions themselves, or conventional personality trait models linked to HiTOP; (ii) alternative trait constructs designed to link conventional personality models and neurobiological measures; and (iii) mechanistic models of neurobiological processes relevant to HiTOP constructs, derived from computational modelling. We discuss the importance of establishing an interface between HiTOP and neurobiology to develop a more comprehensive, mechanistic understanding of psychopathology and to guide the refinement of the HiTOP model. Such efforts have the potential to guide the development and provision of effective, individualized psychological treatment.

Lower Functional Connectivity in Vestibular-Limbic Networks in Individuals With Subclinical Agoraphobia

Background: Agoraphobia was described in 1871 as a condition of fear-related alterations in spatial orientation and locomotor control triggered by places or situations that might cause a patient to panic and feel trapped. In contemporary nosology, however, this original concept of agoraphobia was split into two diagnostic entities, i.e., the modern anxiety disorder of agoraphobia, consisting solely of phobic/avoidant symptoms in public spaces, and the recently defined vestibular disorder of persistent postural perceptual dizziness (PPPD), characterized by dizziness, and unsteadiness exacerbated by visual motion stimuli. Previous neuroimaging studies found altered brain activity and connectivity in visual-vestibular networks of patients with PPPD vs. healthy controls. Neuroticism and introversion, which pre-dispose to both agoraphobia and PPPD, influenced brain responses to vestibular and visual motion stimuli in patients with PPPD. Similar neuroimaging studies have not been undertaken in patients with agoraphobia in its current definition. Given their shared history and pre-disposing factors, we sought to test the hypotheses that individuals with agoraphobic symptoms have alterations in visual-vestibular networks similar to those of patients with PPPD, and that these alterations are influenced by neuroticism and introversion. Methods: Drawing from the Human Connectome Project (HCP) database, we matched 52 participants with sub-clinical agoraphobia and 52 control subjects without agoraphobic symptoms on 19 demographic and psychological/psychiatric variables. We then employed a graph-theoretical framework to compare resting-state functional magnetic resonance images between groups and evaluated the interactive effects of neuroticism and introversion on the brain signatures of agoraphobia. Results: Individuals with subclinical agoraphobia had lower global clustering, efficiency and transitivity relative to controls. They also had lower connectivity metrics in two brain networks, one positioned to process incoming visual space-motion information, assess threat, and initiate/inhibit behavioral responses (visuospatial-emotional network) and one positioned to control and monitor locomotion (vestibular-navigational network). Introversion interacted with agoraphobic symptoms to lower the connectivity of the visuospatial-emotional network. This contrasted with previous findings describing neuroticism-associated higher connectivity in a narrower visual-spatial-frontal network in patients with PPPD. Conclusion: Functional connectivity was lower in two brain networks in subclinical agoraphobia as compared to healthy controls. These networks integrate visual vestibular and emotional response to guide movement in space.

Hippocampal Volume as a Putative Marker of Resilience or Compensation to Minor Depressive Symptoms in a Nonclinical Sample

Case-control studies in major depression have established patterns of regional gray matter loss, including the hippocampus, which might show state-related effects dependent on disease stage. However, there is still limited knowledge on compensation effects that might occur in people resilient to depression showing only subclinical symptoms. We used voxel-based morphometry on a multicenter data set of 409 healthy nonclinical subjects to test the hypothesis that local hippocampal volume would be inversely correlated with subclinical depressive symptoms [Symptom Checklist 90-Revised (SCL-90-R) depression scores]. Our region-of-interest results show a significant (p = 0.042, FWE cluster-level corrected) positive correlation of SCL-90-R scores for depression and a left hippocampus cluster. Additionally, we provide an exploratory finding of gyrification, a surface-based morphometric marker, correlating with a right postcentral gyrus cluster [p = 0.031, family-wise error (FWE) cluster-level corrected]. Our findings provide first preliminary evidence of an inverse relationship for subjects in the absence of clinical depression and might thus point to processes related to compensation. Similar effects have been observed in remission from major depression and thus deserve further study to evaluate hippocampal volume not only as a state-dependent marker of disease but also of resilience.