Altered gray matter morphometry and resting-state functional and structural connectivity in social anxiety disorder

Macrostructural Brain Morphology as Moderator of the Relationship Between Pandemic-Related Stress and Internalizing Symptomology During COVID-19 in High-Risk Adolescents

BACKGROUND

According to person-by-environment models, individual differences in traits may moderate the association between stressors and the development of psychopathology; however, findings in the literature have been inconsistent and little literature has examined adolescent brain structure as a moderator of the effects of stress on adolescent internalizing symptoms. The COVID-19 pandemic presented a unique opportunity to examine the associations between stress, brain structure, and psychopathology. Given links of cortical morphology with adolescent depression and anxiety, the current study investigated whether cortical morphology moderated the relationship between stress from the COVID-19 pandemic and the development of internalizing symptoms in familial high-risk adolescents.

METHODS

Prior to the COVID-19 pandemic, 72 adolescents (27 male) completed a measure of depressive and anxiety symptoms and underwent magnetic resonance imaging. T1-weighted images were acquired to assess cortical thickness and surface area. Approximately 6 to 8 months after COVID-19 was declared a global pandemic, adolescents reported their depressive and anxiety symptoms and pandemic-related stress.

RESULTS

Adjusting for pre-pandemic depressive and anxiety symptoms and stress, increased pandemic-related stress was associated with increased depressive but not anxiety symptoms. This relationship was moderated by cortical thickness and surface area in the anterior cingulate and cortical thickness in the medial orbitofrontal cortex such that increased stress was only associated with increased depressive and anxiety symptoms among adolescents with lower cortical surface area and higher cortical thickness in these regions.

CONCLUSIONS

Results further our understanding of neural vulnerabilities to the associations between stress and internalizing symptoms in general and during the COVID-19 pandemic in particular.

The functional connectivity between right insula and anterior cingulate cortex underlying the association between future self-continuity and delay discounting

Delay discounting refers to the tendency of individuals to devalue future rewards as the delay in their receipt increases over time. Previous studies have indicated that future self-continuity correlates with delay discounting rates. However, the neural basis underlying the relationship between future self-continuity and delay discounting is not clear. To address this question, we used voxel-based morphometry and resting-state functional connectivity analyses to investigate the neural basis underlying the association between future self-continuity and delay discounting. Behavioral result showed that future self-continuity was positively associated with delay discounting. Voxel-based morphometry analysis result indicated that gray matter volume in the right dorsal anterior insula was positively correlated with future self-continuity. Resting-state functional connectivity analysis found that functional connectivity between the right dorsal anterior insula and anterior cingulate cortex was positively associated with future self-continuity. Mediation analysis showed that the right dorsal anterior insula-right anterior cingulate cortex functional connectivity partially mediated the relationship between future self-continuity and delay discounting. These results suggested that right dorsal anterior insula-right anterior cingulate cortex functional connectivity could be the neural basis underlying the association between future self-continuity and delay discounting. In summary, the study provided novel insights into how future self-continuity affected delay discounting and offers new explanations from a neural perspective.

Alterations in cortical thickness of frontoparietal regions in patients with social anxiety disorder

Although functional changes of the frontal and (para)limbic area for emotional hyper-reactivity and emotional dysregulation are well documented in social anxiety disorder (SAD), prior studies on structural changes have shown mixed results. This study aimed to identify differences in cortical thickness between SAD and healthy controls (CON). Thirty-five patients with SAD and forty-two matched CON underwent structural magnetic resonance imaging. A vertex-based whole brain and regional analyses were conducted for between-group comparison. The whole-brain analysis revealed increased cortical thickness in the left insula, left superior parietal lobule, left superior temporal gyrus, and left frontopolar cortex in patients with SAD compared to CON, as well as decreased thickness in the left superior/middle frontal gyrus and left fusiform gyrus in patients (after multiple-correction). The results from the ROI analysis did not align with these findings at the statistically significant level after multiple corrections. Changes in cortical thickness were not correlated with social anxiety symptoms. While consistent results were not obtained from different analysis methods, the results from the whole-brain analysis suggest that patients with SAD exhibit distinct neural deficits in areas involved in salience, attention, and socioemotional processing.

The vmPFC-IPL functional connectivity as the neural basis of future self-continuity impacted procrastination: the mediating role of anticipated positive outcomes

Procrastination is universally acknowledged as a problematic behavior with wide-ranging consequences impacting various facets of individuals' lives, including academic achievement, social accomplishments, and mental health. Although previous research has indicated that future self-continuity is robustly negatively correlated with procrastination, it remains unknown about the neural mechanisms underlying the impact of future self-continuity on procrastination. To address this issue, we employed a free construction approach to collect individuals' episodic future thinking (EFT) thoughts regarding specific procrastination tasks. Next, we conducted voxel-based morphometry (VBM) and resting-state functional connectivity (RSFC) analysis to explore the neural substrates underlying future self-continuity. Behavior results revealed that future self-continuity was significantly negatively correlated with procrastination, and positively correlated with anticipated positive outcome. The VBM analysis showed a positive association between future self-continuity and gray matter volumes in the right ventromedial prefrontal cortex (vmPFC). Furthermore, the RSFC results indicated that the functional connectivity between the right vmPFC and the left inferior parietal lobule (IPL) was positively correlated with future self-continuity. More importantly, the mediation analysis demonstrated that anticipated positive outcome can completely mediate the relationship between the vmPFC-IPL functional connectivity and procrastination. These findings suggested that vmPFC-IPL functional connectivity might prompt anticipated positive outcome about the task and thereby reduce procrastination, which provides a new perspective to understand the relationship between future self-continuity and procrastination.

Functional and Structural Abnormalities in the Pain Network of Generalized Anxiety Disorder Patients with Pain Symptoms

Pain symptoms significantly impact the well-being and work capacity of individuals with generalized anxiety disorder (GAD), and hinder treatment and recovery. Despite existing literature focusing on the neural substrate of pain and anxiety separately, further exploration is needed to understand the possible neuroimaging mechanisms of the pain symptoms in GAD patients. We recruited 73 GAD patients and 75 matched healthy controls (HC) for clinical assessments, as well as resting-state functional and structural magnetic resonance imaging scans. We defined a pain-related network through a published meta-analysis, including the insula, thalamus, periaqueductal gray, prefrontal cortex, anterior cingulate cortex, amygdala, and hippocampus. Subsequently, we conducted the regional homogeneity (ReHo) and the gray matter volume (GMV) within the pain-related network. Correlation analysis was then employed to explore associations between abnormal regions and self-reported outcomes, assessed using the Patient Health Questionnaire-15 (PHQ-15) and pain scores. We observed significantly increased ReHo in the bilateral insula but decreased GMV in the bilateral thalamus of GAD compared to HC. Further correlation analysis revealed a positive correlation between ReHo of the left anterior insula and pain scores in GAD patients, while a respective negative correlation between GMV of the bilateral thalamus and PHQ-15 scores. In summary, GAD patients exhibit structural and functional abnormalities in pain-related networks. The enhanced ReHo in the left anterior insula is correlated with pain symptoms, which might be a crucial brain region of pain symptoms in GAD.

Microstructural white matter alterations associated with social anxiety disorders: A systematic review

BACKGROUND

Social anxiety disorder (SAD) is a psychiatric condition characterized by impaired social functioning that negatively impacts individuals' quality of life. Previous neuroimaging studies have revealed morphological and functional changes in various brain regions associated with SAD. Recent advances in diffusion tensor imaging (DTI) and diffusion-weighted imaging (DWI) have enabled the investigation of microstructural white matter (WM) alterations in SAD. This study aims to provide an overview of DTI/DWI studies exploring WM microstructure changes in SAD.

METHODS

A systematic search on PubMed, Scopus, Web of Science, and PsycINFO was conducted for relevant records on July 8, 2023. An exploratory meta-analysis was also performed.

RESULTS

Eight studies were reviewed. Consistent findings indicated reduced fractional anisotropy and increased diffusivity measures in different WM tracts in SAD patients compared to healthy controls. These alterations were mostly observed within regions of the fronto-limbic network, like uncinate fasciculus (UF) and superior and inferior longitudinal fasciculi (SLF and ILF). Finally, our exploratory meta-analysis on four studies utilizing a voxel-wise analytic approach yielded no significant differences between SAD patients and controls.

LIMITATIONS

Limited number of studies, small sample sizes, and heterogeneity in analysis methods.

CONCLUSIONS

Patients with SAD exhibited altered WM integrity, particularly in the UF, SLF, and ILF, compared to healthy controls. However, due to the limited number of included studies, our meta-analysis yielded no significant differences between SAD patients and controls. Therefore, future research is crucial to unravel the link between altered WM structure and the involvement of other limbic and cortical structures in SAD pathogenesis.

Grey matter structural alterations in anxiety disorders: a voxel-based meta-analysis

Anxiety disorders (ADs) are a group of prevalent and destructive mental illnesses, but the current understanding of their underlying neuropathology is still unclear. Employing voxel-based morphometry (VBM), previous studies have demonstrated several common brain regions showing grey matter volume (GMV) abnormalities. However, contradictory results have been reported among these studies. Considering that different subtypes of ADs exhibit common core symptoms despite different diagnostic criteria, and previous meta-analyses have found common core GMV-altered brain regions in ADs, the present research aimed to combine the results of individual studies to identify common GMV abnormalities in ADs. Therefore, we first performed a systematic search in PubMed, Embase, and Web of Science on studies investigating GMV differences between patients with ADs and healthy controls (HCs). Then, the anisotropic effect-size signed differential mapping (AES-SDM) was applied in this meta-analysis. A total of 24 studies (including 25 data sets) were included in the current study, and 906 patients with ADs and 1003 HCs were included. Compared with the HCs, the patients with ADs showed increased GMV in the left superior parietal gyrus, right angular gyrus, left precentral gyrus, and right lingual gyrus, and decreased GMV in the bilateral insula, bilateral thalamus, left caudate, and right putamen. In conclusion, the current study has identified some abnormal GMV brain regions that are related to the pathological mechanisms of anxiety disorders. These findings could contribute to a better understanding of the underlying neuropathology of ADs.

Examining the relationship between anxiety and regional brain volumes in the National Alzheimer's Coordinating Center uniform, imaging, and biomarker datasets

Anxiety has been associated with a greater risk of Alzheimer's disease (AD). Existing research has identified structural differences in regional brain tissue in participants with anxiety, but results have been inconsistent. We sought to determine the association between anxiety and regional brain volumes, and the moderation effect of APOE ε4. Using data from participants in the National Alzheimer's Coordinating Center (NACC) Uniform Data Set, with complete imaging (MRI) and biomarker data (n = 1533), multiple linear regression estimated the adjusted effect of anxiety on 30 structural MRI regions. The moderation effect of APOE ε4 on the relation between structural MRI regions and anxiety was assessed as was the moderation effect of cognitive status. False discovery rate was used to adjust for multiple comparisons. After controlling for intracranial volume, age, sex, years of education, race, Hispanic ethnicity, and cognitive status, seven MRI regions demonstrated lower volumes among participants with anxiety: total cerebrum gray matter volume, right hippocampus volume, hippocampal volume (total), right and left frontal lobe cortical gray matter volume, and right and total temporal lobe cortical gray matter volume. Findings suggest that anxiety is associated with significant atrophy in multiple brain regions, with corresponding ventricular enlargement. Future research should investigate if anxiety-related changes to brain morphology contribute to greater AD risk.

A systematic review and meta-analysis of resting-state fMRI in anxiety disorders: Need for data sharing to move the field forward

Anxiety disorders are among the most prevalent psychiatric disorders. Neuroimaging findings remain uncertain, and resting state functional magnetic resonance (rs-fMRI) connectivity is of particular interest since it is a scalable functional imaging modality. Given heterogeneous past findings for rs-fMRI in anxious individuals, we characterize patterns across anxiety disorders by conducting a systematic review and meta-analysis. Studies were included if they contained at the time of scanning both a healthy group and a patient group. Due to insufficient study numbers, the quantitative meta-analysis only included seed-based studies. We performed an activation likelihood estimation (ALE) analysis that compared patients and healthy volunteers. All analyses were corrected for family-wise error with a cluster-level threshold of p < .05. Patients exhibited hypo-connectivity between the amygdala and the medial frontal gyrus, anterior cingulate cortex, and cingulate gyrus. This finding, however, was not robust to potential file-drawer effects. Though limited by strict inclusion criteria, our results highlight the heterogeneous nature of reported findings. This underscores the need for data sharing when attempting to detect reliable patterns of disruption in brain activity across anxiety disorders.

The para-hippocampal-medial frontal gyrus functional connectivity mediates the relationship between dispositional optimism and procrastination

Procrastination is a prevalent phenomenon throughout the world, which can lead to worse consequences across life domains, such as academic performance, mental health, and even public policy. Despite the evidence for the association between dispositional optimism and procrastination, the neural mechanisms underlying this link remain unexplored. To address this issue, we employed voxel-based morphometry (VBM) and resting-state functional connectivity (RSFC) methods to explore the underlying links between dispositional optimism and procrastination in a large sample (N=408). The self-report results showed that dispositional optimism was negatively associated with procrastination (r= -.30, p<.001). The VBM analysis indicated that dispositional optimism was positively correlated with gray matter volumes (GMV) in the right para-hippocampal (rPHC), and negatively correlated with GMV in the left cerebellum. Moreover, the functional connectivity analysis with the rPHC as a seed region revealed that rPHC-rMFC (right medial frontal gyrus) functional connectivity was negatively associated with dispositional optimism. Furthermore, the mediation analysis showed that the rPHC-rMFC connectivity partially mediated the relationship between dispositional optimism and procrastination. These results suggested that the rPHC-rMFC connectivity engaged in less task aversiveness by episodic prospection may underlie the association between dispositional optimism and procrastination, which provides a new perspective to understand the relationship between dispositional optimism and procrastination. DATA AVAILABILITY STATEMENT: The data that support the findings of this study are available from the corresponding author upon reasonable request.

Early infant prefrontal gray matter volume is associated with concurrent and future infant emotionality

High levels of infant negative emotionality (NE) are associated with emotional and behavioral problems later in childhood. Identifying neural markers of high NE as well as low positive emotionality (PE) in infancy can provide neural markers to aid early identification of vulnerability, and inform interventions to help delay or even prevent psychiatric disorders before the manifestation of symptoms. Prefrontal cortical (PFC) subregions support the regulation of NE and PE, with each PFC subregion differentially specializing in distinct emotional regulation processes. Gray matter (GM) volume measures show good test-retest reliability, and thus have potential use as neural markers of NE and PE. Yet, while studies showed PFC GM structural abnormalities in adolescents and young adults with affective disorders, few studies examined how PFC subregional GM measures are associated with NE and PE in infancy. We aimed to identify relationships among GM in prefrontal cortical subregions at 3 months and caregiver report of infant NE and PE, covarying for infant age and gender and caregiver sociodemographic and clinical variables, in two independent samples at 3 months (Primary: n = 75; Replication sample: n = 40) and at 9 months (Primary: n = 44; Replication sample: n = 40). In the primary sample, greater 3-month medial superior frontal cortical volume was associated with higher infant 3-month NE (p < 0.05); greater 3-month ventrolateral prefrontal cortical volume predicted lower infant 9-month PE (p < 0.05), even after controlling for 3-month NE and PE. GM volume in other PFC subregions also predicted infant 3- and 9-month NE and PE, together with infant demographic factors, caregiver age, and/or caregiver affective instability and anxiety. These findings were replicated in the independent sample. To our knowledge, this is the first study to determine in primary and replication samples associations among infant PFC GM volumes and concurrent and prospective NE and PE, and identify promising, early markers of future psychopathology risk.

Topography of the Anxious Self: Abnormal Rest-Task Modulation in Social Anxiety Disorder

Social anxiety disorder (SAD) is characterized by social anxiety/fear, self-attention, and interoception. Functional magnetic resonance imaging studies demonstrate increased activity during symptom-sensitive tasks in regions of the default-mode network (DMN), amygdala (AMG), and salience network (SN). What is the source of this task-unspecific symptom-sensitive hyperactivity in DMN? We address this question by probing SAD resting state (rs) changes in DMN including their relation to other regions as possible source of task-unspecific hyperactivity in the same regions. Our findings show the following: (1) rs-hypoconnectivity within-DMN regions; (2) rs-hyperconnectivity between DMN and AMG/SN; (3) task-evoked hyperactivity in the abnormal rs-regions of DMN and AMG/SN during different symptom-sensitive tasks; (4) negative relationship of rest and task changes in especially anterior DMN regions as their rs-hypoconnectivity is accompanied by task-unspecific hyperactivity; (5) abnormal top-down/bottom-up modulation between anterior DMN regions and AMG during rest and task. Findings demonstrate that rs-hypoconnectivity among DMN regions is negatively related to task-unspecific hyperactivity in DMN and AMG/SN. We propose a model of "Topography of the Anxious Self" in SAD (TAS-SAD). Abnormal DMN-AMG/SN topography during rest, as trait feature of an "unstable social self", is abnormally aggravated during SAD-sensitive situations resulting in task-related hyperactivity in the same regions with an "anxious self" as state feature.

Volume of subcortical brain regions in social anxiety disorder: mega-analytic results from 37 samples in the ENIGMA-Anxiety Working Group

There is limited convergence in neuroimaging investigations into volumes of subcortical brain regions in social anxiety disorder (SAD). The inconsistent findings may arise from variations in methodological approaches across studies, including sample selection based on age and clinical characteristics. The ENIGMA-Anxiety Working Group initiated a global mega-analysis to determine whether differences in subcortical volumes can be detected in adults and adolescents with SAD relative to healthy controls. Volumetric data from 37 international samples with 1115 SAD patients and 2775 controls were obtained from ENIGMA-standardized protocols for image segmentation and quality assurance. Linear mixed-effects analyses were adjusted for comparisons across seven subcortical regions in each hemisphere using family-wise error (FWE)-correction. Mixed-effects d effect sizes were calculated. In the full sample, SAD patients showed smaller bilateral putamen volume than controls (left: d = -0.077, pFWE = 0.037; right: d = -0.104, pFWE = 0.001), and a significant interaction between SAD and age was found for the left putamen (r = -0.034, pFWE = 0.045). Smaller bilateral putamen volumes (left: d = -0.141, pFWE < 0.001; right: d = -0.158, pFWE < 0.001) and larger bilateral pallidum volumes (left: d = 0.129, pFWE = 0.006; right: d = 0.099, pFWE = 0.046) were detected in adult SAD patients relative to controls, but no volumetric differences were apparent in adolescent SAD patients relative to controls. Comorbid anxiety disorders and age of SAD onset were additional determinants of SAD-related volumetric differences in subcortical regions. To conclude, subtle volumetric alterations in subcortical regions in SAD were detected. Heterogeneity in age and clinical characteristics may partly explain inconsistencies in previous findings. The association between alterations in subcortical volumes and SAD illness progression deserves further investigation, especially from adolescence into adulthood.

Systematic literature review of human studies assessing the efficacy of cannabidiol for social anxiety

The current review evaluates the potential of cannabidiol (CBD) as a promising pharmacotherapy for social anxiety disorder (SAD). Although a number of evidence-based treatments for SAD are available, less than a third of affected individuals experience symptom remission after one year of treatment. Therefore, improved treatment options are urgently needed, and CBD is one candidate medication that may have certain benefits over current pharmacotherapies, including the absence of sedating side effects, reduced abuse liability, and rapid course of action. The current review provides a brief overview of CBD's mechanisms of action, neuroimaging in SAD, and evidence for CBD's effects on the neural substrates of SAD, as well as systematically reviewing literature directly examining the efficacy of CBD for improving social anxiety among healthy volunteers and individuals with SAD. In both populations, acute CBD administration significantly decreased anxiety without co-occurring sedation. A single study has also shown chronic administration to decrease social anxiety symptoms in individuals with SAD. Collectively, the current literature suggests CBD may be a promising treatment for SAD. However, further research is needed to establish optimal dosing, assess the timecourse of CBD's anxiolytic effects, evaluate long-term CBD administration, and explore sex differences in CBD for social anxiety.

Large-scale dysfunctional white matter and grey matter networks in patients with social anxiety disorder

Dysfunction of large-scale brain networks has been implicated in social anxiety disorder (SAD); most work has focused on grey matter (GM) functional connectivity (FC) abnormalities, whereas white matter (WM) FC alterations remain unclear. Here, using a K-means clustering algorithm, we obtained 8 GM and 10 WM functional networks from a cohort dataset (48 SAD patients and 48 healthy controls). By calculating and comparing FC matrices between SAD group and healthy controls, we demonstrated disrupted connections between the limbic and dorsal prefrontal, lateral temporal, and sensorimotor networks, and between the visual and sensorimotor networks. Furthermore, there were negative correlations between HAMD scores and limbic-dorsal prefrontal and limbic-sensorimotor networks, and between illness duration and sensorimotor-visual networks. These findings reflect the critical role of limbic network, with its extensive connections to other networks, and the neurobiology of disordered cognition processing and emotional regulation in SAD.

Socioeconomic deprivation in early life and symptoms of depression and anxiety in young adulthood: mediating role of hippocampal connectivity

BACKGROUND

Experience of early-life socioeconomic deprivation (ELSD) may increase the risk of mental disorders in young adulthood. This association may be mediated by structural and functional alterations of the hippocampus.

METHODS

We conducted a prospective cohort study on 122 participants of the European Longitudinal Study of Pregnancy and Childhood. Information about ELSD was collected via questionnaire from mothers during the first 18 months of participants' lives. At age 23-24, participants underwent examination by structural magnetic resonance imaging, resting-state functional connectivity and assessment of depressive symptoms (Mood and Feelings Questionnaire) and anxiety (Spielberger State-Trait Anxiety Inventory). The association of ELSD with brain outcomes in young adulthood was assessed with correlations, linear regression (adjusting for sex, socioeconomic position and mother's mental health) and moderated mediation analysis.

RESULTS

Higher ELSD was associated with greater depressive symptoms (B = 0.22; p = 0.001), trait anxiety (B = 0.07; p = 0.02) and lower global connectivity of the right hippocampus (B = -0.01; p = 0.02). These associations persisted when adjusted for covariates. In women, lower global connectivity of the right hippocampus was associated with stronger trait anxiety (B = -4.14; p = 0.01). Global connectivity of the right hippocampus as well as connectivity between the right hippocampus and the left middle temporal gyrus mediated the association between ELSD and trait anxiety in women. Higher ELSD correlated with a lower volume of the right hippocampus in men, but the volume of the right hippocampus was not related to mental health.

CONCLUSIONS

Early preventive strategies targeted at children from socioeconomically deprived families may yield long-lasting benefits for the mental health of the population.

Depression mediates the association between insula-frontal functional connectivity and social interaction anxiety

High rates of comorbidity between depression and anxiety are frequently observed. However, few studies have investigated the relationship between depression and social interaction anxiety using a dimensional approach. The current study aimed to explore the associations between depression and social interaction anxiety with a multivariate approach in a comparably large dataset (n = 194, 95 males). All participants completed a structural and a resting-state functional magnetic resonance imaging (fMRI) scan and self-report measures of depression via Beck's Depression Inventory II and social interaction anxiety by social interaction anxiety scale. Voxel-based morphometry (VBM) results first identified grey matter volumes of insula were positively correlated with depression dimension scores. Next, whole brain seed-to-voxel analyses were conducted using a VBM-identified insula as a seed region to examine associations between depression/social anxiety and functional connectivity. The results suggested that a significant positive effect of depression/social anxiety was found on the connectivity between insula and dorsal lateral prefrontal cortex (dlPFC). Moreover, variations in depression meditated the association between insula-dlPFC connectivity and social interaction anxiety. Overall, the results indicate that individual differences in depression relate more to insula-dlPFC coupling compared to social interaction anxiety.

Pathological fear, anxiety and negative affect exhibit distinct neurostructural signatures: evidence from psychiatric neuroimaging meta-analysis

Internalizing disorders encompass anxiety, fear and depressive disorders, which exhibit overlap at both conceptual and symptom levels. Given that a neurobiological evaluation is lacking, we conducted a Seed-based D-Mapping comparative meta-analysis including coordinates as well as original statistical maps to determine common and disorder-specific gray matter volume alterations in generalized anxiety disorder (GAD), fear-related anxiety disorders (FAD, i.e., social anxiety disorder, specific phobias, panic disorder) and major depressive disorder (MDD). Results showed that GAD exhibited disorder-specific altered volumes relative to FAD including decreased volumes in left insula and lateral/medial prefrontal cortex as well as increased right putamen volume. Both GAD and MDD showed decreased prefrontal volumes compared to controls and FAD. While FAD showed less robust alterations in lingual gyrus compared to controls, this group presented intact frontal integrity. No shared structural abnormalities were found. Our study is the first to provide meta-analytic evidence for distinct neuroanatomical abnormalities underlying the pathophysiology of anxiety-, fear-related and depressive disorders. These findings may have implications for determining promising target regions for disorder-specific neuromodulation interventions (e.g. transcranial magnetic stimulation or neurofeedback).

Gray matter microstructural alterations in manganese-exposed welders: a preliminary neuroimaging study

OBJECTIVES

Chronic occupational manganese (Mn) exposure is characterized by motor and cognitive dysfunction. This study aimed to investigate structural abnormalities in Mn-exposed welders compared to healthy controls (HCs).

METHODS

Thirty-five HCs and forty Mn-exposed welders underwent magnetic resonance imaging (MRI) scans in this study. Based on T1-weighted MRI, the voxel-based morphometry (VBM), structural covariance, and receiver operating characteristic (ROC) curve were applied to examine whole-brain structural changes in Mn-exposed welders.

RESULTS

Compared to HCs, Mn-exposed welders had altered gray matter volume (GMV) mainly in the medial prefrontal cortex, lentiform nucleus, hippocampus, and parahippocampus. ROC analysis indicated the potential highest classification power of the hippocampus/parahippocampus. Moreover, distinct structural covariance patterns in the two groups were associated with regions, mainly including the thalamus, insula, amygdala, sensorimotor area, and middle temporal gyrus. No significant relationships were found between the findings and clinical characteristics.

CONCLUSIONS

Our findings showed Mn-exposed welders had changed GMV and structural covariance patterns in some regions, which implicated in motivative response, cognitive control, and emotional regulation. These results might provide preliminary evidence for understanding the pathophysiology of Mn overexposure.

KEY POINTS

• Chronic Mn exposure might be related to abnormal brain structural neural mechanisms. • Mn-exposed welders had morphological changes in brain regions implicated in emotional modulation, cognitive control, and motor-related response. • Altered gray matter volume in the hippocampus/parahippocampus and putamen might serve as potential biomarkers for Mn overexposure.

Structural and functional deficits and couplings in the cortico-striato-thalamo-cerebellar circuitry in social anxiety disorder

Although functional and structural abnormalities in brain regions involved in the neurobiology of fear and anxiety have been observed in patients with social anxiety disorder (SAD), the findings have been heterogeneous due to small sample sizes, demographic confounders, and methodological differences. Besides, multimodal neuroimaging studies on structural-functional deficits and couplings are rather scarce. Herein, we aimed to explore functional network anomalies in brain regions with structural deficits and the effects of structure-function couplings on the SAD diagnosis. High-resolution structural magnetic resonance imaging (MRI) and resting-state functional MRI images were obtained from 49 non-comorbid patients with SAD and 53 demography-matched healthy controls. Whole-brain voxel-based morphometry analysis was conducted to investigate structural alterations, which were subsequently used as seeds for the resting-state functional connectivity analysis. In addition, correlation and mediation analyses were performed to probe the potential roles of structural-functional deficits in SAD diagnosis. SAD patients had significant gray matter volume reductions in the bilateral putamen, right thalamus, and left parahippocampus. Besides, patients with SAD demonstrated widespread resting-state dysconnectivity in cortico-striato-thalamo-cerebellar circuitry. Moreover, dysconnectivity of the putamen with the cerebellum and the right thalamus with the middle temporal gyrus/supplementary motor area partially mediated the effects of putamen/thalamus atrophy on the SAD diagnosis. Our findings provide preliminary evidence for the involvement of structural and functional deficits in cortico-striato-thalamo-cerebellar circuitry in SAD, and may contribute to clarifying the underlying mechanisms of structure-function couplings for SAD. Therefore, they could offer insights into the neurobiological substrates of SAD.

Resting-state neuroimaging in social anxiety disorder: a systematic review

There has been a growing interest in resting-state brain alterations in people with social anxiety disorder. However, the evidence has been mixed and contested and further understanding of the neurobiology of this disorder may aid in informing methods to increase diagnostic accuracy and treatment targets. With this systematic review, we aimed to synthesize the findings of the neuroimaging literature on resting-state functional activity and connectivity in social anxiety disorder, and to summarize associations between brain and social anxiety symptoms to further characterize the neurobiology of the disorder. We systematically searched seven databases for empirical research studies. Thirty-five studies met the inclusion criteria, with a total of 1611 participants (795 people with social anxiety disorder and 816 controls). Studies involving resting-state seed-based functional connectivity analyses were the most common. Individuals with social anxiety disorder (vs. controls) displayed both higher and lower connectivity between frontal-amygdala and frontal-parietal regions. Frontal regions were the most consistently implicated across other analysis methods, and most associated with social anxiety symptoms. Small sample sizes and variation in the types of analyses used across studies may have contributed to the inconsistencies in the findings of this review. This review provides novel insights into established neurobiological models of social anxiety disorder and provides an update on what is known about the neurobiology of this disorder in the absence of any overt tasks (i.e., resting state). The knowledge gained from this body of research enabled us to also provide recommendations for a more standardized imaging pre-processing approach to examine resting-state brain activity and connectivity that could help advance knowledge in this field. We believe this is warranted to take the next step toward clinical translation in social anxiety disorder that may lead to better treatment outcomes by informing the identification of neurobiological targets for treatment.

Altered Local Brain Amplitude of Fluctuations in Patients With Myotonic Dystrophy Type 1

This study is aimed at investigating the characteristics of the spontaneous brain activity in patients with myotonic dystrophy type 1 (DM1). A total of 18 patients with DM1 and 18 healthy controls (HCs) were examined by resting-state functional MRI. Combined methods include amplitude of low-frequency fluctuations (ALFFs), the fractional amplitude of low-frequency fluctuations (fALFFs), and Wavelet transform-based ALFFs (Wavelet-ALFFs) with standardization, percent amplitude of fluctuation (PerAF) with/without standardization were applied to evaluate the spontaneous brain activity of patients with DM1. Compared with HCs, patients with DM1 showed decreased ALFFs and Wavelet-ALFFs in the bilateral precuneus (PCUN), angular gyrus (ANG), inferior parietal, but supramarginal and angular gyri (IPL), posterior cingulate gyrus (PCG), superior frontal gyrus, medial (SFGmed), middle occipital gyrus (MOG), which were mainly distributed in the brain regions of default mode network (DMN). Decreased ALFFs and Wavelet-ALFFs were also seen in bilateral middle frontal gyrus (MFG), inferior frontal gyrus, opercular part (IFGoperc), which were the main components of the executive control network (ECN). Patients with DM1 also showed decreased fALFFs in SFGmed.R, the right anterior cingulate and paracingulate gyri (ACGR), bilateral MFG. Reduced PerAF in bilateral PCUN, ANG, PCG, MOG, and IPLL as well as decreased PerAF without standardization in PCUNR and bilateral PCG also existed in patients with DM1. In conclusion, patients with DM1 had decreased activity in DMN and ECN with increased fluctuations in the temporal cortex and cerebellum. Decreased brain activity in DMN was the most repeatable and reliable with PCUN and PCG being the most specific imaging biomarker of brain dysfunction in patients with DM1.

Structural and functional brain abnormalities in misophonia

Misophonia is a newly described condition in which specific ordinary sounds provoke disproportionately strong negative affect. Since evidence for neurobiological abnormalities underlying misophonia is scarce, we tested whether misophonia patients differed from healthy controls in grey matter volumes and resting-state functional connectivity. We collected structural magnetic resonance imaging and resting-state functional magnetic resonance imaging data from 24 misophonia patients and 25 matched controls. Compared to controls, voxel-based morphometry showed larger right amygdala volume in misophonia patients. Follow-up seed-based functional connectivity analysis of the amygdala showed a different pattern of connectivity with the cerebellum, driven by greater connectivity with the left amygdala. Additional data-driven independent component analysis showed greater connectivity within lateral occipital cortices and fusiform gyri in the ventral attention network. We propose that the amygdala enlargement may be associated with heightened emotional reactivity in misophonia. The higher connectivity between left amygdala and cerebellum might be linked to a tendency to exhibit reflex-like physical reactions to triggers. Higher attention network connectivity may reflect sensory enhancement of visual triggers or visual imagery related to trigger sounds. In sum, we found structural and functional abnormalities which implicate dysfunction of emotional and attentional systems in misophonia.

Investigating white matter structure in social anxiety disorder using fixel-based analysis

Social anxiety disorder (SAD) is one of the most common mental health disorders in youth, defined by a persistent and intense fear of negative evaluation by others. Recent research has examined its neurological underpinnings, including structural connectivity changes in the brain. This has been examined through measurement of the white matter (WM) structure of fibre pathways. Previous studies have shown inconsistent results. This study attempts to resolve these inconsistencies by utilising a recently proposed, advanced method for diffusion MRI analysis, known as fixel based analysis (FBA). This technique enables examination of WM macro- and micro-structure with measures of fibre density (FD), fibre bundle cross-section (FC) and fibre density-cross-section (FDC). This study evidenced increased FDC in a region of the right superior longitudinal fasciculus (SLF) from a whole brain FBA, along with increased FC and FDC from an analysis restricted to a-priori tracts of interest, in regions of the right inferior longitudinal fasciculus (R-ILF). The average FDC of the left uncinate fasciculus (L-UF) was also increased. To examine the relationship between WM structure and severity of symptoms, these FBA metrics were correlated with Leibowitz Social Anxiety Scale (LSAS) scores. From the tract-restricted analysis an inverse correlation between FC and LSAS scores was found in the R-ILF. The average FC of the R-ILF was also inversely correlated with symptom severity. By utilising a more sensitive and fibre-specific method of analysis than previous studies, these findings highlight innovative outcomes relating to white matter in numerous fibre tracts.

Neural basis underlying the relation between boredom proneness and procrastination: The role of functional coupling between precuneus/cuneus and posterior cingulate cortex

Procrastination refers to voluntarily delaying an important task despite the fact that this decision will take a heavy toll on daily life. Previous researches have shown that boredom proneness is a robust predictor of procrastination and the default mode network (DMN) could be the neural substrate for the connection between the two variables mentioned above. However, how boredom proneness links to procrastination at the neural level remains unclear. To address this question, we adopted the voxel-based morphometry (VBM) and resting-state functional connectivity (RSFC) methods to identify the neural basis of the relation between boredom proneness and procrastination. Behavioral results indicated that boredom proneness was significantly positively correlated with procrastination. VBM results revealed that boredom proneness was negatively correlated with grey matter volumes in the precuneus/cuneus. Furthermore, the RSFC analyses showed that the functional connectivity between precuneus/cuneus and posterior cingulate cortex (PCC) was positively correlated with boredom proneness. More importantly, a mediation analysis found that boredom proneness played a fully mediating role in improving the relationship between precuneus/cuneus-PCC functional connectivity and procrastination. These findings suggest that the brain functional connectivity engages in attention control may account for the association between boredom proneness and procrastination, and highlight the important role of sustaining concentration on mitigating procrastination.

Structural brain correlates in major depression, anxiety disorders and post-traumatic stress disorder: A voxel-based morphometry meta-analysis

The high comorbidity of Major Depressive Disorder (MDD), Anxiety Disorders (ANX), and Posttraumatic Stress Disorder (PTSD) has hindered the study of their structural neural correlates. The authors analyzed specific and common grey matter volume (GMV) characteristics by comparing them with healthy controls (HC). The meta-analysis of voxel-based morphometry (VBM) studies showed unique GMV diminutions for each disorder (p < 0.05, corrected) and less robust smaller GMV across diagnostics (p < 0.01, uncorrected). Pairwise comparison between the disorders showed GMV differences in MDD versus ANX and in ANX versus PTSD. These results endorse the hypothesis that unique clinical features characterizing MDD, ANX, and PTSD are also reflected by disorder specific GMV correlates.

Intrinsic functional connectivity in families genetically enriched for social anxiety disorder - an endophenotype study

BACKGROUND

Social anxiety disorder (SAD) is a serious psychiatric condition with a high prevalence, and a typical onset during childhood/adolescence. The condition runs in families, but it is largely unknown which neurobiological characteristics transfer this genetic vulnerability ('endophenotypes'). Using data from the Leiden Family Lab study on SAD, including two generations of families genetically enriched for SAD, we investigated whether social anxiety (SA) co-segregated with changes in intrinsic functional connectivity (iFC), and examined heritability.

METHODS

Functional MRI data were acquired during resting-state in 109 individuals (56 males; mean age: 31·5, range 9·2-61·5 years). FSL's tool MELODIC was used to perform independent component analysis. Six networks of interest (default mode, dorsal attention, executive control, frontoparietal, limbic and salience) were identified at the group-level and used to generate subject-specific spatial maps. Voxel-wise regression models, with SA-level as predictor and voxel-wise iFC as candidate endophenotypes, were performed to investigate the association with SA, within masks of the networks of interest. Subsequently, heritability was estimated.

FINDINGS

SA co-segregated with iFC within the dorsal attention network (positive association in left middle frontal gyrus and right postcentral gyrus) and frontoparietal network (positive association within left middle temporal gyrus) (cluster-forming-threshold z>2·3, cluster-corrected extent-threshold p<0·05). Furthermore, iFC of multiple voxels within these clusters was at least moderately heritable.

INTERPRETATION

These findings provide initial evidence for increased iFC as candidate endophenotype of SAD, particularly within networks involved in attention. These changes might underlie attentional biases commonly present in SAD.

FUNDING

Leiden University Research Profile 'Health, Prevention and the Human Lifecycle'.

Cognitive performance shows domain specific associations with regional cortical thickness in multiple sclerosis

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Cognitive impairment correlates with loss of cortical thickness in MS.

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Cognitive tests show distinctive regional associations with cortical thickness.

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Some regions, such as the left insula, correlate with multiple tests.

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Associations patterns seem reproducible in patients with very mild impairment.

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Better localization of cognitive functions may improve future MRI studies.

Multiple Sclerosis (MS) patients often suffer from significant cognitive impairment. Earlier research has shown relationships between regional cortical atrophy and cognitive deterioration. However, due to a large number of neuropsychological assessments and a heterogenous pattern of cognitive deficits in MS patients, reported associations patterns are also heterogenous. Using an extensive neuropsychological battery of 23 different tasks, we explored domain (attention/information processing, memory, spatial processing, executive functioning) and task-specific associations with regional cortical thickness in a representative sample of MS patients (N = 97). Cortical regions associated with multiple cognitive tasks in the left hemisphere were predominantly located in the inferior insula (attention p < 0.001, memory p = 0.047, spatial processing p = 0.004, executive functioning p = 0.037), the gyrus frontalis superior (attention p = 0.015, memory p = 0.037, spatial processing p = 0.033, executive functioning p = 0.017) and temporal medial (attention p < 0.001, memory two clusters p = 0.016 and p < 0.001, executive functioning p = 0.016). In the right hemisphere, we detected the strongest association in the sulcus interparietalis with five cluster (attention SDMT p = 0.003 and TAP_DA p < 0.001; memory Rey recall p = 0.013 and VLMT verbal learning p = 0.016; spatial processing Rey copy p < 0.001). We replicated parts of our results in an independent sample of 30 mildly disabled MS patients. Moreover, comparisons to 29 healthy controls showed that the regional associations seemed to represent rather pathophysiological dependency than a physiological one. We believe that our results may prove useful in diagnosis and rehabilitation of cognitive impairments and may serve as guidance in future magnetic resonance imaging (MRI) studies.

Distinct grey matter volume alterations in adult patients with panic disorder and social anxiety disorder: A systematic review and voxel-based morphometry meta-analysis

BACKGROUND

The paradox of similar diagnostic criteria but potentially different neuropathologies in panic disorder (PD) and social anxiety disorder (SAD) needs to be clarified.

METHODS

We performed a qualitative systematic review and a quantitative whole-brain voxel-based morphometry (VBM) meta-analysis with an anisotropic effect-size version of seed-based D mapping (AES-SDM) to explore whether the alterations of grey matter volume (GMV) in PD are similar to or different from those in SAD, together with potential confounding factors.

RESULTS

A total of thirty-one studies were eligible for inclusion, eighteen of which were included in the meta-analysis. Compared to the respective healthy controls (HC), qualitative and quantitative analyses revealed smaller cortical-subcortical GMVs in PD patients in brain areas including the prefrontal and temporal-parietal cortices, striatum, thalamus and brainstem, predominantly right-lateralized regions, and larger GMVs in the prefrontal and temporal-parietal-occipital cortices, and smaller striatum and thalamus in SAD patients. Quantitatively, the right inferior frontal gyrus (IFG) deficit was specifically implicated in PD patients, whereas left striatum-thalamus deficits were specific to SAD patients, without shared GMV alterations in both disorders. Sex, the severity of clinical symptoms, psychiatric comorbidity, and concomitant medication use were negatively correlated with smaller regional GMV alterations in PD patients.

CONCLUSION

PD and SAD may represent different anxiety sub-entities at the neuroanatomical phenotypes level, with different specific neurostructural deficits in the right IFG of PD patients, and the left striatum and thalamus of SAD patients. This combination of differences and specificities can potentially be used to guide the development of diagnostic biomarkers for these disorders.

Cortical activity during social acceptance and rejection task in social anxiety disorder: A controlled functional near infrared spectroscopy study

BACKGROUND

The cognitive and emotional vulnerability of individuals with social anxiety disorder (SAD) and their response to repeated experiences of social rejection and social acceptance are important factors for the emergence and maintenance of symptoms of the disorder. Functional neuroimaging studies of SAD reveal hyperactivity in regions involved in the fear circuit such as amygdala, insula, anterior cingulate, and prefrontal cortices (PFC) in response to human faces with negative emotions. Observation of brain activity, however, involving studies of responses to standardized human interaction of social acceptance and social rejection have been lacking.

METHODS

We compared a group of index subjects with SAD (N = 22, mean age:26.3 ± 5.4, female/male: 7/15) (SADG) with a group of healthy controls (CG) (N = 21, mean age:28.7 ± 4.5, female/male: 14/7) in measures of cortical activity during standardized experiences of human interaction involving social acceptance (SA) and social rejection (SR) video-simulated handshaking tasks performed by real actors. In a third, control condition (CC), the subjects were expected to press a switch button in an equivalent space. Subjects with a concurrent mood episode were excluded and the severity of subclinical depressive symptoms was controlled. 52-channel functional near-infrared spectroscopy (fNIRS) was used to measure cortical activity.

RESULTS

Activity was higher in the SAD subjects compared to healthy controls, in particular in channels that project to middle and superior temporal gyri (STG), frontal eye fields (FEF) and dorsolateral prefrontal cortex (DLPFC) in terms of both SA and SR conditions. Cortical activity during the CC was not different between the groups. Only in the SAD-group, activity in the pre-motor and supplementary motor cortices, inferior and middle temporal gyri and fronto-polar area was higher during the rejection condition than the other two conditions. Anxiety scores were correlated with activity in STG, DLPFC, FEF and premotor cortex, while avoidance scores were correlated with activity in STG and FEF.

CONCLUSIONS

SA and SR are represented differently in terms of cortical activity in SAD subjects compared to healthy controls. Higher activity in both social conditions in SAD subjects compared to controls may imply biological sensitivity to these experiences and may underscore the importance of increased cortical activity during social interaction experiences as a putative mediator of vulnerability to SAD. Higher cortical activity in the SADG may possibly indicate stronger need for inhibitory control mechanisms and higher recruitment of theory of mind functions during social stress. Higher activity during the SR compared to the SA condition in the SAD subjects may also suggest distinct processing of social cues, whether they involve acceptance or rejection.

The neural basis underlying the relation between the action identification level and delay discounting: The medial and orbital frontal cortex functional connectivity with the precuneus

Previous studies have elucidated that action identification level brings ubiquitous effects in human life. The higher identification level is widely associated with future-oriented perspective, goal-directed actions, less impulsivity and so forth. However, little is known about how it relates to delay discounting. To address this issue, we sought to investigate the neural underpinning to understand their relations using voxel-based morphometry (VBM) and resting-state functional connectivity (RSFC) approaches. The behavioral results revealed that higher identification level was correlated with less discounting rate. The VBM results showed that gray matter (GM) volumes in left orbitofrontal cortex (OFC), left medial prefrontal cortex (mPFC) and right superior frontal gyrus (SFG) were positively correlated with action identification level. The RSFC results found that action identification level was positively associated with the functional connectivity between left OFC-left precuneus, and left mPFC-right precuneus respectively. Moreover, the structural equation modeling (SEM) showed that the association between the identification level and delay discounting was completely mediated by coupling of combined left OFC-left precuneus and left mPFC-right precuneus. These findings suggested that the functional communications within these brain regions in valuation and episodic prospection may account for the relationship between action identification level and delay discounting. The results enhanced our understanding of their relations from neural basis.

Altered resting-state fMRI signals and network topological properties of bipolar depression patients with anxiety symptoms

BACKGROUND

This study aims to explore the changes in functional neuroimaging in bipolar depression patients with anxiety symptoms (BDP-A).

METHODS

Forty-five BDP-A patients, 22 bipolar depression patients without anxiety symptoms (BDP-NA), and 48 healthy controls (HC) were finally involved. The low-frequency oscillation characteristics, functional connectivity (FC), and network properties among the three groups of participants were analyzed.

RESULTS

Compared with the BDP-NA group, BDP-A patients exhibited significantly decreased amplitude of low-frequency fluctuation (ALFF) in the left middle frontal gyrus (MFG), superior occipital gyrus, and inferior parietal, but supramarginal and angular gyri (IPL). Enhanced FC from left IPL to middle temporal gyrus, from left precentral gyrus (PreCG) to bilateral angular gyri, medial superior frontal gyrus, and left superior frontal gyrus (SFG)/MFG were also revealed. Compared with HC, the BDP-A group showed remarkably increased ALFF in the left MFG/PreCG, right superior parietal gyrus, while decreased ALFF in the left inferior frontal gyrus, opercular part, and SFG. In addition, higher regional homogeneity in the left MFG/PreCG was found.

LIMITATIONS

The limitations are as follows: (1) relatively small sample size; (2) not all the patients were drug-naive; (3) lack of pure anxiety disorder patients as a controlled group; (4) mental health conditions of HC were not systemic evaluated.

CONCLUSIONS

BDP-A patients showed significant differences in resting-state fMRI properties when compared with BDP-NA or HC group. These results may infer the dysfunction of the dorsal attention network, the default network, and the fronto-limbic system as well as disrupted brain network efficiency in BDP-A patients.

Investigating microstructure of white matter tracts as candidate endophenotypes of Social Anxiety Disorder - Findings from the Leiden Family Lab study on Social Anxiety Disorder (LFLSAD)

BACKGROUND

Social anxiety disorder (SAD) is a mental illness with a complex, partially genetic background. Differences in characteristics of white matter (WM) microstructure have been reported in patients with SAD compared to healthy controls. Also, WM characteristics are moderately to highly heritable. Endophenotypes are measurable characteristics on the road from genotype to phenotype, putatively reflective of genetically based disease mechanisms. In search of candidate endophenotypes of SAD we used a unique sample of SAD patients and their family members of two generations to explore microstructure of WM tracts as candidate endophenotypes. We focused on two endophenotype criteria: co-segregation with social anxiety within the families, and heritability.

METHODS

Participants (n = 94 from 8 families genetically vulnerable for SAD) took part in the Leiden Family Lab Study on Social Anxiety Disorder (LFLSAD). We employed tract-based spatial statistics to examine structural WM characteristics, being fractional anisotropy (FA), axial diffusivity (AD), mean diffusivity (MD) and radial diffusivity (RD), in three a-priori defined tracts of interest: uncinate fasciculus (UF), superior longitudinal fasciculus (SLF) and inferior longitudinal fasciculus (ILF). Associations with social anxiety symptoms and heritability were estimated.

RESULTS

Increased FA in the left and right SLF co-segregated with symptoms of social anxiety. These findings were coupled with decreased RD and MD. All characteristics of WM microstructure were estimated to be at least moderately heritable.

CONCLUSION

These findings suggest that alterations in WM microstructure in the SLF could be candidate endophenotypes of SAD, as they co-segregated within families genetically vulnerable for SAD and are heritable. These findings further elucidate the genetic susceptibility to SAD and improve our understanding of the overall etiology.

Dissociations in cortical thickness and surface area in non-comorbid never-treated patients with social anxiety disorder

BACKGROUND

Abnormalities of functional activation and cortical volume in brain regions involved in the neurobiology of fear and anxiety have been implicated in the pathophysiology of social anxiety disorder (SAD). However, few studies have performed separate measurements of cortical thickness (CT) and cortical surface area (CSA) which reflect different neurobiological processes. Thus, we aimed to explore the cortical morphological anomaly separately in SAD using FreeSurfer.

METHODS

High-resolution structural magnetic resonance images were obtained from 32 non-comorbid never-treated adult SAD patients and 32 demography-matched healthy controls. Cortical morphometry indices including CT and CSA were separately determined by FreeSurfer and compared between the two groups via whole-brain vertex-wise analysis, while partial correlation analysis using age and gender as covariates were conducted.

FINDINGS

The patients with SAD showed decreased CT but increased CSA near-symmetrically in the bilateral prefrontal cortex (PFC) of the dorsolateral, dorsomedial, and ventromedial subdivisions, as well as the right lateral orbitofrontal cortex; increased CSA in the left superior temporal gyrus (STG) was also observed in SAD. The CSA in the left PFC was negatively correlated with the disease duration.

INTERPRETATION

As the balloon model hypothesis suggests that the tangentially stretched cortex may cause dissociations in cortical morphometry and affect the cortical capacity for information processing, our findings of dissociated morphological alterations in the PFC and cortical expansion in the STG may reflect the morphological alterations of the functional reorganization in those regions, and highlight the important role of those structures in the pathophysiology and neurobiology of SAD.

FUNDING

This study was funded by the National Natural Science Foundation of China (Grant Nos. 31700964, 31800963, 81621003, and 81820108018).

Frontal white matter abnormalities reveal the pathological basis underlying negative symptoms in antipsychotic-naïve, first-episode patients with adolescent-onset schizophrenia: Evidence from multimodal brain imaging

A major challenge in schizophrenia is to uncover the pathophysiological basis of its negative symptoms. Recent neuroimaging studies revealed that disrupted structural properties of frontal white matter (FWM) are associated with the negative symptoms of schizophrenia. However, there is little direct functional evidence of FWM for negative symptoms in schizophrenia. To address this issue, we combined resting-state connectome-wide functional connectivity (FC) and diffusion tensor imaging tractography to investigate the alteration of FWM underlying the negative symptoms in 39 drug-naive patients with adolescent-onset schizophrenia (AOS) and 31 age- and sex- matched healthy controls (HCs). Results revealed that the intrinsic FC and structural properties (fraction anisotropy and fibers) of the left FWM correspond to individual negative symptoms in AOS. Moreover, the serotonin network (raphe nuclei, anterior and posterior cingulate cortices, and prefrontal and inferior parietal cortices) and FWM-cingulum network were found to contributed to the negative symptom severity in AOS. Furthermore, the patients showed abnormal functional and structural connectivities between the interhemispheric FWM compared with HCs. Importantly, the decreased fiber counts between the interhemispheric FWM were inversely correlated with the negative symptoms in AOS. Our findings demonstrated the association between FWM and negative symptoms, and offered initial evidence by using WM connectome to uncover WM functional information in schizophrenia.

Mnemonic discrimination and social anxiety: the role of state anxiety

The Mnemonic Similarity Task (MST) measures mnemonic discrimination, or the ability to correctly identify new stimuli from highly similar, old stimuli. Poor mnemonic discrimination is a potential risk or maintenance factor for anxiety, and recent studies suggest state affect may moderate relations between mnemonic discrimination and trait anxiety. No studies have evaluated mnemonic discrimination in specific subtypes of anxiety or with clinically relevant stressors. This preregistered study evaluated the role of social anxiety and the anticipation of a future speech on MST performance. Participants with high (n = 66) and low (n = 64) levels of social anxiety were randomly assigned to a stressor condition or a control condition prior to the MST. State anxiety was measured throughout the study. Results did not indicate significant effects of trait (high vs. low social anxiety) or state anxiety (stressor condition vs. control condition) on mnemonic discrimination. Results are compared with previous research and implications and future directions are discussed.

Disrupted dynamic local brain functional connectivity patterns in generalized anxiety disorder

Previous studies have reported abnormalities in static brain activity and connectivity in patients with generalized anxiety disorder (GAD). However, the dynamic patterns of brain connectivity in patients with GAD have not been fully explored. In this study, we aimed to investigate the dynamic local brain functional connectivity in patients with GAD using dynamic regional phase synchrony (DRePS), a newly developed method for assessing intrinsic dynamic local functional connectivity. Seventy-four patients with GAD and 74 healthy controls (HCs) were enrolled and underwent resting-state functional magnetic resonance imaging. Compared to the HCs, patients with GAD exhibited decreased DRePS values in the bilateral caudate, left hippocampus, left anterior insula, left inferior frontal gyrus, and right fusiform gyrus extending to inferior temporal gyrus. The DRePS value of the left hippocampus was negatively correlated with the Hamilton Anxiety Rating Scale scores. Moreover, these abnormal DRePS patterns could be used to distinguish patients with GAD from HCs in an independent sample (18 patients with GAD and 21 HCs). Our findings provide further evidence on brain dysfunction in GAD from the perspective of the dynamic behaviour of local connections, suggesting that patients with GAD may have an insufficient brain adaptation. This study provides new insights into the neurocognitive mechanism of GAD and could potentially inform the diagnosis and treatment of this disease. Future studies on GAD could benefit from combining the DRePS method with task-related functional magnetic resonance imaging and non-invasive brain stimulation.

White Matter Structural Brain Connectivity of Young Healthy Individuals With High Trait Anxiety

Background: Although functional brain connectivity in anxiety-related disorders has been studied, brain connectivity in non-clinical populations with high trait anxiety has been rarely reported. Whether structural brain connectivity changes in young healthy individuals with high trait anxiety remains unknown.

Methods: Thirty-eight young healthy individuals with high anxiety levels and 34 healthy subjects with low anxiety levels who were matched by age, gender, and educational level were recruited. Diffusion tensor images were acquired to analyze white matter connectivity. A two-sample t-test was used for group comparison of weighted networks and graph properties.

Results: Different connections were detected in fractional anisotropy- and fiber number-weighted networks. These connections were widely distributed in various regions, where relative significance was located in the inter-hemispheric frontal lobe, the frontal-limbic lobe in the right intra-hemisphere, and the frontal-temporal lobe in the ipsilateral hemisphere. However, no significant difference was found in fiber length-weighted network and in graph properties among the three networks.

Conclusions: The structural connectivity of white matter may be a vulnerability marker. Hence, healthy individuals with high trait anxiety levels are susceptible to anxiety-related psychopathology. The findings may help elucidate the pathological mechanism of anxiety and establish interventions for populations susceptible to anxiety disorders.

Nucleus accumbens volume as a predictor of anxiety symptom improvement following CBT and SSRI treatment in two independent samples

Structural variations of neural regions implicated in fear responses have been well documented in the pathophysiology of anxiety and may play an important role in treatment response. We examined whether gray matter volume of three neural regions supporting fear and avoidance responses [bilateral amygdala, nucleus accumbens (NAcc), and ventromedial prefrontal cortex (PFC)] predicted cognitive-behavioral therapy (CBT) and selective serotonin reuptake inhibitor (SSRI) treatment outcome in two independent samples of patients with anxiety disorders. Study 1 consisted of 81 adults with anxiety disorders and Study 2 included 55 children and adolescents with anxiety disorders. In both studies, patients completed baseline structural MRI scans and received either CBT or SSRI treatment. Clinician-rated interviews of anxiety symptoms were assessed at baseline and posttreatment. Among the adult sample, greater pre-treatment bilateral NAcc volume was associated with a greater reduction in clinician-rated anxiety symptoms pre-to-post CBT and SSRI treatment. Greater left NAcc volume also predicted greater decreases in clinician-rated anxiety symptoms pre-to-post CBT and SSRI treatment among youth with current anxiety. Across studies, results were similar across treatments, and findings were maintained when adjusting for patient's age, sex, and total intracranial brain volume. We found no evidence for baseline amygdala or ventromedial PFC volume serving as treatment predictors across the two samples. Together, these findings provide promising support for the role of NAcc volume as an objective marker of anxiety treatment improvement that spans across development. Future studies should clarify the specific mechanisms through which NAcc volume exerts its therapeutic effects.

Amygdala volume and social anxiety symptom severity: Does segmentation technique matter?

The amygdala factors prominently in neurobiological models of social anxiety (SA), yet amygdala volume findings regarding SA have been inconsistent and largely focused on case-control characterization. One source of discrepant findings could be variability in volumetric techniques. Therefore, we compared amygdala volumes derived via an automated technique (Freesurfer) against a manually corrected approach, also involving Freesurfer. Additionally, we tested whether the relationship between volume and SA symptom severity would differ across volumetric techniques. We pooled participants (n = 76) from archival studies. SA severity was assessed with the Liebowitz Social Anxiety Scale; scores ranged from non-clinical to clinical levels. Freesurfer produced significantly larger amygdalar volumes for participants with poor image quality. Even after excluding such participants, paired sample t-tests showed Freesurfer's boundaries produced significantly larger amygdalar volumes than manually corrected ones, bilaterally. Yet, intra-class correlation coefficients between the two methods were high, which suggests that Freesurfer's over-estimation of amygdala volume was systemic. Regardless of segmentation technique, volumes were not associated with SA symptom severity. Potentially, amygdala sub-regions may yield clearer patterns regarding SA symptoms. Further, our study underscores the importance of image quality for segmentation of the amygdala, and image quality may be particularly valuable when examining anatomical data for subtle inter-individual differences.

Meditation effect in changing functional integrations across large-scale brain networks: Preliminary evidence from a meta-analysis of seed-based functional connectivity

Meditation is a type of mental training commonly applied in clinical settings and also practiced for general well-being. Brain functional connectivity (FC) patterns associated with meditation have revealed its brain mechanisms. However, the variety of FC methods applied has made it difficult to identify brain communication patterns associated with meditation. Here we carried out a coordinate-based meta-analysis to get preliminary evidence of meditation effects on changing brain network interactions. Fourteen seed-based, voxel-wise FC studies reported in 13 publications were reviewed; 10 studies with seeds in the default mode network (DMN) were meta-analyzed. Seed coordinates and the effect sizes in statistically significant regions were extracted, based on 170 subjects in meditation groups and 163 subjects in control groups. Seed-based d-mapping was used to analyze meditation versus control FC differences with DMN seeds. Meditation was associated with increased connectivity within DMN and between DMN and somatomotor network and with decreased connectivity between DMN and frontoparietal network (FPN) as well as ventral attention network (VAN). The pattern of decreased within-DMN FC and increased between-network FC (FPN and DAN with DMN) was more robust in highly experienced meditators compared to less experienced individuals. The identified neural network interactions may also promote meditation’s effectiveness in clinical interventions for treating physical and mental disorders.

White Matter-Based Structural Brain Network of Anxiety

Anxiety disorders are characterized by excessive fear and anxiety and related behavioral disturbances. Because diffusion tensor imaging is sensitive to detect subtle pathology of the brain, it has been used to characterize differences in white matter microstructure for a broad spectrum of psychiatric disorders. The neurobiological underpinnings of a trait anxiety seem to be associated with the uncinate fasciculus, a major pathway between the amygdala and orbitofrontal cortex. Apparent WM micro-alterations in patients with panic disorder are present in diverse and widespread regions, although alterations vary in terms of clinical symptom severity and comorbidities. Social anxiety disorder is associated with structural dysconnectivity in a fronto-limbic network consistent with reduced fractional anisotropy values in uncinate fasciculus and inferior longitudinal fasciculus. The pathogenesis of obsessive-compulsive disorder may include abnormal findings in not only the fronto-striato-thalamic circuit but also the posterior and temporal regions of forceps major and cingulum bundle. Studies of white matter status in anxiety revealed overlapping patterns of front-cortical and fronto-limbic changes with uncinate fasciculus and cingulum alterations a frequent component.

The neural substrates responsible for how trait anxiety affects delay discounting: Right hippocampal and cerebellar connectivity with bistable right inferior parietal lobule

Delay discounting, an indicator of impulsivity, refers to the extent of devaluing future rewards. Studies have found that individuals with trait anxiety generally depreciate the later larger rewards, showing steeper delay discounting rates. However, little is known about the neural substrates responsible for how trait anxiety affects individuals' delay discounting. To address this question, we employed the voxel-based morphometry (VBM) and resting-state functional connectivity (RSFC) methods to explore the neural substrates of trait anxiety responsible for delay discounting. Behavioral results showed that trait anxiety was significantly positively correlated with delay discounting rates. The VBM analysis revealed that gray matter volumes of the right hippocampus (RHPC) and right cerebellum (RCere) were significantly positively correlated with trait anxiety. Moreover, the RSFC results showed that bistable right inferior parietal lobule (RIPL) connectivity with the RHPC and RCere were all inversely associated with trait anxiety. More importantly, mediation analysis indicated that trait anxiety played a completely mediating role in the relation between functional connectivity of RHPC-RIPL and RCere-RIPL and delay discounting. These results suggested that bistable RIPL connectivity with RHPC and RCere could be neural substrates underlying the effect of trait anxiety on delay discounting. On the whole, the current study yields insights into how trait anxiety affects delay discounting and provides a novel account from a neural basis perspective.

Limbic and prefrontal neural volume modulate social anxiety in children at temperamental risk

BACKGROUND

Clinical levels of a social anxiety disorder (SAD) often appear during childhood and rise to a peak during late adolescence. The temperament trait behavioral inhibition (BI), evident early in childhood, has been linked to increased risk for SAD. Functional and structural variations in brain regions associated with the identification of, and response to, fear may support the BI-SAD relation. Whereas relevant functional studies are emerging, the few extant structural studies have focused on adult samples with mixed findings.

METHODS

A moderated-mediation model was used to examine the relations between BI, SAD symptoms, and brain-volume individual differences in a sample of children at risk for anxiety (ages 9-12; N = 130, 52 BI).

RESULTS

Our findings indicate that at higher levels of BI, children with smaller anterior insula volumes showed stronger correlations between BI and SAD. In addition, larger ventrolateral prefrontal cortex (vlPFC) volumes were associated with fewer SAD symptoms.

CONCLUSIONS

These findings support previous reports linking SAD levels with variations in volume and reactivity in both limbic (insula) and prefrontal (vlPFC) regions. These findings set the foundation for further examination of networks of neural structures that influence the transition from BI to SAD across development, helping further clarify mechanisms of risk and resilience.

Temporal dynamics of spontaneous default-mode network activity mediate the association between reappraisal and depression

Cognitive reappraisal is associated with major depressive disorder (MDD), while spontaneous activity patterns of the default mode network (DMN) is implicated in reappraisal and MDD. However, neural mechanisms subserving the close association of spontaneous reappraisal and depression are unclear. Spontaneous reappraisal, depression and resting-state functional magnetic resonance imaging (rsfMRI) were measured from 105 healthy subjects. We assessed the temporal complexity (Hurst exponent), Regional Homogeneity (ReHo) and fractional Amplitude of Low Frequency Fluctuation (fALFF) profiles of DMN, a network involved in both reappraisal and depression. Mediation effects of these standard measures on the relationship between reappraisal and depression, and the contributions of each DMN subregion, were assessed. Results indicated that Hurst exponent (H) of DMN, whether extracted by independent component analysis (ICA) or region of interest (ROI), was significantly associated with reappraisal scores. An individual with a higher reappraisal score has a lower Hurst value of DMN. Mediation analyses suggest that H of DMN partially mediates the association between reappraisal and the degree of depression, and this mediation effect arises from the contribution of medial prefrontal cortex. Neither ReHo nor fALFF showed a similar correlation or mediation effect. These findings suggest that temporal dynamics of DMN play an important role in emotion regulation and its association with depression. H of DMN may serve as a neural marker mediating the association between reappraisal and depression.

High Self-Control Reduces Risk Preference: The Role of Connectivity Between Right Orbitofrontal Cortex and Right Anterior Cingulate Cortex

Risk preference, the preference for risky choices over safe alternatives, has a great impact on many fields, such as physical health, sexual safety and financial decision making. Ample behavioral research has attested that inadequate self-control can give rise to high risk preference. However, little is known about the neural substrates underlying the effect of self-control on risk preference. To address this issue, we combined voxel-based morphometry (VBM) with resting-state functional connectivity (RSFC) analyses to explore the neural basis underlying the effect of self-control on risk preference across two independent samples. In sample 1 (99 participants; 47 males; 20.37 ± 1.63 years), the behavioral results indicated that the scores of self-control were significantly and negatively correlated with risk preference (indexed by gambling rate). The VBM analyses demonstrated that the higher risk preference was correlated with smaller gray matter volumes in right orbitofrontal cortex (rOFC) and right posterior parietal cortex. In the independent sample 2 (80 participants; 33 males; 20.33 ± 1.83 years), the RSFC analyses ascertained that the functional connectivity of rOFC and right anterior cingulate cortex (rACC) was positively associated with risk preference. Furthermore, the mediation analysis identified that self-control mediated the impact of functional connectivity of rOFC-rACC on risk preference. These findings suggest the functional coupling between the rOFC and rACC might account for the association between self-control and risk preference. The present study extends our understanding on the relationship between self-control and risk preference, and reveals possible neural underpinnings underlying this association.

Altered Uncinate Fasciculus Microstructure in Childhood Anxiety Disorders in Boys But Not Girls

OBJECTIVE

Anxiety disorders are common, can result in lifelong suffering, and frequently begin before adolescence. Evidence from adults suggests that altered prefrontal-limbic connectivity is a pathophysiological feature of anxiety disorders. More specifically, in adults with anxiety disorders, decreased fractional anisotropy (FA), a measure of white matter integrity, has been observed in the uncinate fasciculus, the major tract that connects limbic and prefrontal regions. Because of the early onset of anxiety disorders and the increased incidence in anxiety disorders in females during their reproductive years, it is important to understand whether the reduction in uncinate fasciculus FA exists in children with anxiety disorders and the extent to which this alteration is sex related. To address these issues, the authors assessed FA in the uncinate fasciculus in unmedicated boys and girls with anxiety disorders.

METHODS

FA measures were derived from diffusion tensor images that were acquired from 98 unmedicated children (ages 8-12); 52 met criteria for generalized anxiety disorder, separation anxiety disorder, social anxiety disorder, or anxiety disorder not otherwise specified, and 46 were matched control subjects.

RESULTS

Tract-based results demonstrated that children with anxiety disorders have significant reductions in uncinate fasciculus FA. A significant sex-by-group interaction and post hoc testing revealed that this effect was evident only in boys. No other main effects or sex-by-group interactions were found for other white matter tracts.

CONCLUSIONS

These findings provide evidence of uncinate fasciculus white matter alterations in boys with anxiety disorders. The data demonstrate that anxiety disorder-related alterations in prefrontal-limbic structural connectivity are present early in life, are not related to psychotropic medication exposure, and are sex specific. Building on these findings, future research has the potential to provide insights into the genesis and sexual dimorphism of the pathophysiology that leads to anxiety disorders, as well as to identify sex-specific early-life treatment targets.

Posttraumatic stress disorder, social anxiety disorder and childhood trauma: Differences in hippocampal subfield volume

Volume-based hippocampal findings in Social Anxiety Disorder (SAD) and Posttraumatic Stress Disorder (PTSD) have been inconsistent, with very little investigation of hippocampal subfields. We assessed the effects of early childhood trauma on hippocampal subfields in participants with SAD with and without early childhood trauma and PTSD, compared to healthy controls. The sample comprised 26 participants SAD with early childhood trauma, 22 participants with SAD without early childhood trauma, 17 with PTSD secondary to early childhood trauma and 25 control participants. We used Freesurfer version 6 to determine hippocampal subfield volumes. Findings included significant reduction in right parasubiculum volume between the PTSD group secondary to early childhood trauma and the SAD group without early childhood trauma, as well as a significant reduction in left HATA (Hippocampal Amygdala Transition Area) volume between PTSD with early childhood trauma compared to controls, as well as compared to SAD with early childhood trauma. These findings did withstand correction for multiple resting using the false discovery rate. Our findings of an association of reduced volumes in the parasubiculum and HATA regions with PTSD secondary to childhood trauma are interesting. Further work should investigate whether parasubiculum and HATA regional volume reductions in PTSD are a specific effect of early childhood trauma or a specific manifestation of PTSD pathology. Further work should also be undertaken to determine if hippocampal subfield atrophy is associated with SAD in the setting of early childhood maltreatment.

Developmental changes in resting-state functional networks among individuals with and without internalizing psychopathologies

BACKGROUND

Three well-established intrinsic connectivity networks (ICNs) involved in cognitive-affective processing include the cognitive control network (CCN), default mode network (DMN), and salience and emotional network (SEN). Despite recent advances in understanding developmental changes in these ICNs, the majority of research has focused on single seeds or networks in isolation with limited age ranges. Additionally, although internalizing psychopathologies (IPs), such as anxiety and depression, are often characterized by maladaptive cognitive-affective processing styles, it is not clear how IP history influences age-related changes in brain networks.

METHOD

The current study aimed to characterize the normative development of the CCN, DMN, and SEN across a large age-span (7-29 year olds) of typically developing (TD) individuals (n = 97). We also explore how age may impact differences in network connectivity between TD individuals and patients with IPs (n = 136).

RESULTS

Among TD individuals, DMN and CCN connectivity strengthened with age, whereas connectivity between the SEN and ventromedial prefrontal cortex weakened across development. When exploring group (IP vs. TD) differences, the IP group was characterized by greater connectivity between the CCN and cerebellum and between the SEN and caudate from childhood to early adulthood, relative to TD individuals. In addition, patients with IPs, versus TD individuals, exhibited reduced connectivity between the SEN and medial frontal gyrus from adolescence to adulthood.

CONCLUSIONS

The current findings shed light on differential age-related changes in brain network patterns among psychiatrically free, TD individuals and those with internalizing disorders, and may provide plausible targets for novel mechanism-based treatments that differ based on developmental stage.

Neural bases underlying the association between balanced time perspective and trait anxiety

The aims of present study were to investigate the association between balanced time perspective (BTP) and trait anxiety, and the neural substrates underlying this association using voxel-based morphometry (VBM) and resting-state functional connectivity (RSFC) methods. 140 college students (83 females) ranging in age from 17 to 25 years were assessed on deviation from the balanced time perspective (DBTP) and trait anxiety. Behavioral analyses found BTP could significantly predict trait anxiety after controlling age and gender. Whole-brain VBM analyses found that DBTP was positively correlated with gray matter volume (GMV) in the parahippocampal gyrus (PHG) and precuneus, while trait anxiety positively correlated with GMV in the PHG. Considering the overlapping region in the PHG, we further defined the overlapping region as the seed, and calculated seed-to-voxel-based functional connectivity in resting-state. RSFC results showed that DBTP was positively associated with the RSFC between the PHG and medial prefrontal cortex (mPFC), posterior cingulate cortex (PCC), and precuneus, whereas negatively correlated with the RSFC between the PHG and cuneus. Trait anxiety was also positively correlated with the RSFC between the PHG and PCC while negatively correlated with the RSFC between the PHG and cuneus. Mediation analysis further found GMV in the overlapping PHG and PHG-PCC, PHG-cuneus functional connectivity played significantly mediating roles in the relation between DBTP and trait anxiety. In sum, our research suggests the structural features of the PHG and its connectivity with PCC and cuneus may be the neural bases underlying the association between BTP and trait anxiety.