White matter abnormalities in adolescents with generalized anxiety disorder: a diffusion tensor imaging study

Sex-Specific Distributed White Matter Microarchitectural Alterations in Preadolescent Youths With Anxiety Disorders: A Mega-Analytic Study

OBJECTIVE

Anxiety disorders are among the most common psychiatric disorders in youths and emerge during childhood. This is also a period of rapid white matter (WM) development, which is critical for efficient neuronal communication. Previous work in preadolescent children with anxiety disorders demonstrated anxiety disorder-related reductions in WM microstructural integrity (fractional anisotropy [FA]) in the uncinate fasciculus (UF), the major WM tract facilitating prefrontal cortical-limbic structural connectivity. Importantly, this association was found only in boys with anxiety disorders. To confirm this finding and more comprehensively understand WM changes in childhood anxiety, this mega-analytic study characterizes WM alterations related to anxiety disorders and sex in the largest sample of preadolescent children to date.

METHODS

Diffusion tensor imaging data from published studies of preadolescent children with anxiety disorders and healthy volunteers (ages 8-12) (N=198) were combined with a new data set (N=97) for a total sample of 165 children with anxiety disorders and 132 healthy volunteers. Children with anxiety disorders met DSM-5 criteria for current generalized, separation, and/or social anxiety disorder. Analyses of tractography and voxel-wise data assessed between-group differences (anxiety disorder vs. healthy volunteer), effects of sex, and their interaction.

RESULTS

Tract-based and voxel-wise analyses confirmed a significant reduction in UF FA in boys but not girls with anxiety disorders. Results also demonstrated other significant widespread anxiety disorder-related WM alterations specifically in boys, including in multiple commissural, association, projection, and brainstem regions.

CONCLUSIONS

In addition to confirming male-specific anxiety disorder-related reductions in UF FA, the results demonstrate that anxiety disorders in boys and not girls are associated with broadly distributed WM alterations across the brain. These findings support further studies focused on understanding the extent to which WM alterations in boys with anxiety disorders are involved in pathophysiological processes that mediate anxiety disorders. The findings also suggest the possibility that WM microarchitecture could serve as a novel treatment target for childhood anxiety disorders.

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.

A preliminary study of the effects of an antimuscarinic agent on anxious behaviors and white matter microarchitecture in nonhuman primates

Myelination subserves efficient neuronal communication, and alterations in white matter (WM) microstructure have been implicated in numerous psychiatric disorders, including pathological anxiety. Recent work in rodents suggests that muscarinic antagonists may enhance myelination with behavioral benefits; however, the neural and behavioral effects of muscarinic antagonists have yet to be explored in non-human primates (NHP). Here, as a potentially translatable therapeutic strategy for human pathological anxiety, we present data from a first-in-primate study exploring the effects of the muscarinic receptor antagonist solifenacin on anxious behaviors and WM microstructure. 12 preadolescent rhesus macaques (6 vehicle control, 6 experimental; 8F, 4M) were included in a pre-test/post-test between-group study design. The experimental group received solifenacin succinate for ~60 days. Subjects underwent pre- and post-assessments of: 1) anxious temperament (AT)-related behaviors in the potentially threatening no-eye-contact (NEC) paradigm (30-min); and 2) WM and regional brain metabolism imaging metrics, including diffusion tensor imaging (DTI), quantitative relaxometry (QR), and FDG-PET. In relation to anxiety-related behaviors expressed during the NEC, significant Group (vehicle control vs. solifenacin) by Session (pre vs. post) interactions were found for freezing, cooing, and locomotion. Compared to vehicle controls, solifenacin-treated subjects exhibited effects consistent with reduced anxiety, specifically decreased freezing duration, increased locomotion duration, and increased cooing frequency. Furthermore, the Group-by-Session-by-Sex interaction indicated that these effects occurred predominantly in the males. Exploratory whole-brain voxelwise analyses of post-minus-pre differences in DTI, QR, and FDG-PET metrics revealed some solifenacin-related changes in WM microstructure and brain metabolism. These findings in NHPs support the further investigation of the utility of antimuscarinic agents in targeting WM microstructure as a means to treat pathological anxiety.

Prenatal and Postnatal Maternal Depressive Symptoms Are Associated With White Matter Integrity in 5-Year-Olds in a Sex-Specific Manner

BACKGROUND

Prenatal and postnatal maternal psychological distress predicts various detrimental consequences on social, behavioral, and cognitive development of offspring, especially in girls. Maturation of white matter (WM) continues from prenatal development into adulthood and is thus susceptible to exposures both before and after birth.

METHODS

WM microstructural features of 130 children (mean age, 5.36 years; range, 5.04-5.79 years; 63 girls) and their association with maternal prenatal and postnatal depressive and anxiety symptoms were investigated with diffusion tensor imaging, tract-based spatial statistics, and regression analyses. Maternal questionnaires were collected during first, second, and third trimesters and at 3, 6, and 12 months postpartum with the Edinburgh Postnatal Depression Scale (EPDS) for depressive symptoms and Symptom Checklist-90 for general anxiety. Covariates included child's sex; child's age; maternal prepregnancy body mass index; maternal age; socioeconomic status; and exposures to smoking, selective serotonin reuptake inhibitors, and synthetic glucocorticoids during pregnancy.

RESULTS

Prenatal second-trimester EPDS scores were positively associated with fractional anisotropy in boys (p < .05, 5000 permutations) after controlling for EPDS scores 3 months postpartum. In contrast, postpartum EPDS scores at 3 months correlated negatively with fractional anisotropy (p < .01, 5000 permutations) in widespread areas only in girls after controlling for prenatal second-trimester EPDS scores. Perinatal anxiety was not associated with WM structure.

CONCLUSIONS

These results suggest that prenatal and postnatal maternal psychological distress is associated with brain WM tract developmental alterations in a sex- and timing-dependent manner. Future studies including behavioral data are required to consolidate associative outcomes for these alterations.

Systematic Review: White Matter Microstructural Organization in Adolescents With Depression

Objective

A growing body of literature has focused on the neural mechanisms of depression. Our goal was to conduct a systematic review on the white matter microstructural differences in adolescents with depressive disorders vs adolescents without depressive disorders.

Method

We searched PubMed and PsycINFO for publications on August 3, 2022 (original search conducted in July 2021). The review was registered on PROSPERO (registration number: CRD42021268200), and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. Eligible studies were original research papers comparing diffusion tensor/spectrum imaging findings in adolescents with vs without depression (originally ages 12-19 years, later expanded to 11-21 years). Studies were excluded if they focused on depression exclusively in the context of another condition, used only dimensional depressive symptom assessment(s), or used the same dataset as another included publication.

Results

The search yielded 575 unique records, of which 14 full-text papers were included (824 adolescents with depression and 686 without depression). The following white matter regions showed significant differences in fractional anisotropy in at least 3 studies: uncinate fasciculus, cingulum, anterior corona radiata, inferior fronto-occipital fasciculus, and corpus callosum (genu and body). Most studies reported decreased, rather than increased, fractional anisotropy in adolescents with depression. Limitations include the possibility for selective reporting bias and risk of imprecision, given the small sample sizes in some studies.

Conclusion

Our systematic review suggests aberrant white matter microstructure in limbic-cortical-striatal-thalamic circuits, and the corpus callosum, in adolescents with depression. Future research should focus on developmental trajectories in depression, identifying sources of heterogeneity and integrating findings across imaging modalities.

Translating Developmental Neuroscience to Understand Risk for Psychiatric Disorders

The transition from childhood to adulthood represents the developmental time frame in which the majority of psychiatric disorders emerge. Recent efforts to identify risk factors mediating the susceptibility to psychopathology have led to a heightened focus on both typical and atypical trajectories of neural circuit maturation. Mounting evidence has highlighted the immense neural plasticity apparent in the developing brain. Although in many cases adaptive, the capacity for neural circuit alteration also induces a state of vulnerability to environmental perturbations, such that early-life experiences have long-lasting implications for cognitive and emotional functioning in adulthood. The authors outline preclinical and neuroimaging studies of normative human brain circuit development, as well as parallel efforts covered in this issue of the Journal, to identify brain circuit alterations in psychiatric disorders that frequently emerge in developing populations. Continued translational research into the interactive effects of neurobiological development and external factors will be crucial for identifying early-life risk factors that may contribute to the emergence of psychiatric illness and provide the key to optimizing treatments.

Depressive symptoms, anxiety and cognitive impairment: emerging evidence in multiple sclerosis

Neuropsychiatric abnormalities may be broadly divided in two categories: disorders of mood, affect, and behavior and abnormalities affecting cognition. Among these conditions, clinical depression, anxiety and neurocognitive disorders are the most common in multiple sclerosis (MS), with a substantial impact on patients' quality of life and adherence to treatments. Such manifestations may occur from the earliest phases of the disease but become more frequent in MS patients with a progressive disease course and more severe clinical disability. Although the pathogenesis of these neuropsychiatric manifestations has not been fully defined yet, brain structural and functional abnormalities, consistently observed with magnetic resonance imaging (MRI), together with genetic and immunologic factors, have been suggested to be key players. Even though the detrimental clinical impact of such manifestations in MS patients is a matter of crucial importance, at present, they are often overlooked in the clinical setting. Moreover, the efficacy of pharmacologic and non-pharmacologic approaches for their amelioration has been poorly investigated, with the majority of studies showing marginal or no beneficial effect of different therapeutic approaches, possibly due to the presence of multiple and heterogeneous underlying pathological mechanisms and intrinsic methodological limitations. A better evaluation of these manifestations in the clinical setting and improvements in the understanding of their pathophysiology may offer the potential to develop tools for differentiating these mechanisms in individual patients and ultimately provide a principled basis for treatment selection. This review provides an updated overview regarding the pathophysiology of the most common neuropsychiatric symptoms in MS, the clinical and MRI characteristics that have been associated with mood disorders (i.e., depression and anxiety) and cognitive impairment, and the treatment approaches currently available or under investigation.

Alterations in the inferior fronto-occipital fasciculus - a specific neural correlate of gender incongruence?

BACKGROUND

Increasing numbers of adolescents seek help for gender-identity questions. Consequently, requests for medical treatments, such as puberty suppression, are growing. However, studies investigating the neurobiological substrate of gender incongruence (when birth-assigned sex and gender identity do not align) are scarce, and knowledge about the effects of puberty suppression on the developing brain of transgender youth is limited.

METHODS

Here we cross-sectionally investigated sex and gender differences in regional fractional anisotropy (FA) as measured by diffusion MR imaging, and the impact of puberty on alterations in the white-matter organization of 35 treatment-naive prepubertal children and 41 adolescents with gender incongruence, receiving puberty suppression. The transgender groups were compared with 79 age-matched, treatment-naive cisgender (when sex and gender align) peers.

RESULTS

We found that transgender adolescents had lower FA in the bilateral inferior fronto-occipital fasciculus (IFOF), forceps major and corpus callosum than cisgender peers. In addition, average FA values of the right IFOF correlated negatively with adolescents' cumulative dosage of puberty suppressants received. Of note, prepubertal children also showed significant FA group differences in, again, the right IFOF and left cortico-spinal tract, but with the reverse pattern (transgender > cisgender) than was seen in adolescents.

CONCLUSIONS

Importantly, our results of lower FA (indexing less longitudinal organization, fiber coherence, and myelination) in the IFOF of gender-incongruent adolescents replicate prior findings in transgender adults, suggesting a salient neural correlate of gender incongruence. Findings highlight the complexity with which (pubertal) sex hormones impact white-matter development and add important insight into the neurobiological substrate associated with gender incongruence.

The impact of loneliness and social adaptation on depressive symptoms: Behavioral and brain measures evidence from a brain health perspective

Introduction

Early detection of depression is a cost-effective way to prevent adverse outcomes on brain physiology, cognition, and health. Here we propose that loneliness and social adaptation are key factors that can anticipate depressive symptoms.

Methods

We analyzed data from two separate samples to evaluate the associations between loneliness, social adaptation, depressive symptoms, and their neural correlates.

Results

For both samples, hierarchical regression models on self-reported data showed that loneliness and social adaptation have negative and positive effects on depressive symptoms. Moreover, social adaptation reduces the impact of loneliness on depressive symptoms. Structural connectivity analysis showed that depressive symptoms, loneliness, and social adaptation share a common neural substrate. Furthermore, functional connectivity analysis demonstrated that only social adaptation was associated with connectivity in parietal areas.

Discussion

Altogether, our results suggest that loneliness is a strong risk factor for depressive symptoms while social adaptation acts as a buffer against the ill effects of loneliness. At the neuroanatomical level, loneliness and depression may affect the integrity of white matter structures known to be associated to emotion dysregulation and cognitive impairment. On the other hand, socio-adaptive processes may protect against the harmful effects of loneliness and depression. Structural and functional correlates of social adaptation could indicate a protective role through long and short-term effects, respectively. These findings may aid approaches to preserve brain health via social participation and adaptive social behavior.

Anxiety symptoms and puberty interactively predict lower cingulum microstructure in preadolescent Latina girls

Preadolescence is a period of increased vulnerability for anxiety, especially among Latina girls. Reduced microstructure (fractional anisotropy; FA) of white matter tracts between limbic and prefrontal regions may underlie regulatory impairments in anxiety. However, developmental research on the association between anxiety and white matter microstructure is mixed, possibly due to interactive influences with puberty. In a sample of 39 Latina girls (8-13 years), we tested whether pubertal stage moderated the association between parent- and child-reported anxiety symptoms and FA in the cingulum and uncinate fasciculus. Parent- but not child-reported anxiety symptoms predicted lower cingulum FA, and this effect was moderated by pubertal stage, such that this association was only significant for prepubertal girls. Neither anxiety nor pubertal stage predicted uncinate fasciculus FA. These findings suggest that anxiety is associated with disruptions in girls' cingulum white matter microstructure and that this relationship undergoes maturational changes during puberty.

Morphological similarity of amygdala-ventral prefrontal pathways represents trait anxiety in younger and older adults

Stronger amygdala-ventral prefrontal white matter connectivity has been associated with lower trait anxiety, possibly reflecting an increased capacity for efficient communication between the two regions. However, there are also reports arguing against this brain-anxiety association. To address these inconsistencies in the literature, we tested the possibility that idiosyncratic tract morphology may account for meaningful individual differences in trait anxiety, even among those with comparable microstructural integrity. Here, we adopted intersubject representational similarity analysis, an analytic framework that captures multivariate patterns of similarity, to analyze the morphological similarity of amygdala-ventral prefrontal pathways. Data drawn from the Leipzig Study for Mind-Body-Emotion Interactions dataset showed that younger adults (20 to 35 y of age) with low trait anxiety, in contrast to trait-anxious individuals, had consistently similar morphological configurations in their left amygdala-ventral prefrontal pathways. Additional tests on an independent sample of older adults (60 to 75 y of age) validated this finding. Our study reveals a generalizable pattern of brain-anxiety association that is embedded within the shared geometries between fiber tract morphology and trait anxiety data.

White matter integrity in adolescent irritability: A preliminary study

Irritability is a prevalent, impairing transdiagnostic symptom, especially during adolescence, yet little is known about irritability's neural mechanisms. A few studies examined the integrity of white matter tracts that facilitate neural communication in irritability, but only with extreme, disorder-related symptom presentations. In this preliminary study, we used a group connectometry approach to identify white matter tracts correlated with transdiagnostic irritability in a community/clinic-based sample of 35 adolescents (mean age = 14 years, SD = 2.0). We found positive and negative associations with irritability in local white matter tract bundles including sections of the longitudinal fasciculus; frontoparietal, parolfactory, and parahippocampal cingulum; corticostriatal and thalamocortical radiations; and vertical occipital fasciculus. Our findings support functional neuroimaging studies that implicate widespread neural pathways, particularly emotion and reward networks, in irritability. Our findings of positive and negative associations reveal a complex picture of what is "good" white matter connectivity. By characterizing irritability's neural underpinnings, targeted interventions may be developed.

Exploring the course of adolescent anxiety and depression: associations with white matter tract microstructure

Cross-sectional Diffusion Tensor Imaging (DTI) studies have reported alterations in white matter (WM) microstructure in adolescents with internalizing psychopathology. Yet, longitudinal studies investigating the course of WM microstructure are lacking. This study explored WM alterations and its relation to clinical symptoms over time in adolescents with internalizing disorders. DTI scans were acquired at baseline and after three months in 22 adolescents with clinical depression and comorbid anxiety (INT), and 21 healthy peers (HC) (age: 12-18). Tract-based spatial statistics was used for three voxelwise analyses: i) changes in WM microstructure between and within the INT and HC group; ii) associations between changes in symptom severity and changes in WM microstructure within youths with INT; and iii) associations between baseline WM parameters with changes in symptom severity within youths with INT. Data did not reveal changes in WM microstructure between or within groups over three months' time nor associations between changes in WM microstructure and changes in self-reported symptoms (analyses corrected for age, gender and puberty stage). Lower baseline levels of fractional anisotropy (FA) in the right posterior corona radiata (PCR) and right cingulum were associated with a higher decrease of depressive symptoms within the INT group. Post hoc analysis of additional WM parameters in the significant FA clusters showed that higher levels of baseline mean diffusivity and radial diffusivity in the PCR were associated with a lower decrease in depressive symptoms. Baseline WM microstructure characteristics were associated with a higher decrease in depressive symptoms over time. These findings increase our understanding of neurobiological mechanisms underlying the course of internalizing disorders in adolescents.

Reduced structural integrity of the uncinate fasciculus in incarcerated women scoring high on psychopathy

Both men and women scoring high on psychopathy exhibit similar structural and functional neural abnormalities, including reduced volume of the orbitofrontal cortex (OFC) and reduced hemodynamic activity in the amygdala during affective processing experimental paradigms. The uncinate fasciculus (UF) is a white matter (WM) tract that connects the amygdala to the OFC. Reduced structural integrity of the UF, measured via fractional anisotropy (FA), is commonly associated with men scoring high on psychopathy. However, only one study to date has investigated the relationship between psychopathic traits and UF structural integrity in women, recruiting participants from a community sample. Here, we investigated whether Hare Psychopathy Checklist-Revised (PCL-R) facet scores (measuring interpersonal, affective, lifestyle/behavioral, and antisocial psychopathic traits, respectively) were associated with reduced FA in the left and right UF in a sample of 254 incarcerated women characterized by a wide range of psychopathy scores. We observed that PCL-R Facet 3 scores, assessing lifestyle/behavioral psychopathic traits, were associated with reduced FA in the left and right UF, even when controlling for participant's age and history of previous substance use. The results obtained in the current study help improve our understanding of structural abnormalities associated with women scoring high on psychopathy. Specifically, reduced UF structural integrity may contribute to some of the deficits commonly associated with women scoring high on psychopathy, including emotion dysregulation.

Comparative Functional Connectivity of Core Brain Regions between Implicit and Explicit Memory Tasks Underlying Negative Emotion in General Anxiety Disorder

Objective

To investigate not only differential patterns of functional connectivity of core brain regions between implicit and explicit verbal memory tasks underlying negatively evoked emotional condition, but also correlations of functional connectivity (FC) strength with clinical symptom severity in patients with generalized anxiety disorder (GAD).

Methods

Thirteen patients with GAD and 13 healthy controls underwent functional magnetic resonance imaging for memory tasks with negative emotion words.

Results

Clinical symptom and its severities of GAD were potentially associated with abnormalities of task-based FC with core brain regions and distinct FC patterns between implicit vs. explicit memory processing in GAD were potentially well discriminated. Outstanding FC in implicit memory task includes positive connections of precentral gyus (PrG) to inferior frontal gyrus and inferior parietal gyrus (IPG), respectively, in encoding period; a positive connection of amygdala (Amg) to globus pallidus as well as a negative connection of Amg to cerebellum in retrieval period. Meanwhile, distinct FC in explicit memory included a positive connection of PrG to inferior temporal gyrus (ITG) in encoding period; a positive connection of the anterior cingulate gyrus to superior frontal gyrus in retrieval period. Especially, there were positive correlation between GAD-7 scores and FC of PrG-IPG (r² = 0.324, p = 0.042) in implicit memory encoding, and FC of PrG-ITG (r² = 0.378, p = 0.025) in explicit memory encoding.

Conclusion

This study clarified differential patterns of brain activation and relevant FC between implicit and explicit verbal memory tasks underlying negative emotional feelings in GAD. These findings will be helpful for an understanding of distinct brain functional mechanisms associated with clinical symptom severities in GAD.

Transdiagnostic role of glutamate and white matter damage in neuropsychiatric disorders: A Systematic Review

Neuropsychiatric disorders including generalized anxiety disorder (GAD), obsessive-compulsive disorder (OCD), major depressive disorder (MDD), bipolar disorder (BD), and schizophrenia (SZ) have been considered distinct categories of diseases despite their overlapping characteristics and symptomatology. We aimed to provide an in-depth review elucidating the role of glutamate/Glx and white matter (WM) abnormalities in these disorders from a transdiagnostic perspective. The PubMed online database was searched for studies published between 2010 and 2021. After careful screening, 401 studies were included. The findings point to decreased levels of glutamate in the Anterior Cingulate Cortex in both SZ and BD, whereas Glx is elevated in the Hippocampus in SZ and MDD. With regard to WM abnormalities, the Corpus Callosum and superior Longitudinal Fascicle were the most consistently identified brain regions showing decreased fractional anisotropy (FA) across all the reviewed disorders, except GAD. Additionally, the Uncinate Fasciculus displayed decreased FA in all disorders, except OCD. Decreased FA was also found in the inferior Longitudinal Fasciculus, inferior Fronto-Occipital Fasciculus, Thalamic Radiation, and Corona Radiata in SZ, BD, and MDD. Decreased FA in the Fornix and Corticospinal Tract were found in BD and SZ patients. The Cingulum and Anterior Limb of Internal Capsule exhibited decreased FA in MDD and SZ patients. The results suggest a gradual increase in severity from GAD to SZ defined by the number of brain regions with WM abnormality which may be partially caused by abnormal glutamate levels. WM damage could thus be considered a potential marker of some of the main neuropsychiatric disorders.

A dynamic relation between whole-brain white matter microstructural integrity and anxiety symptoms in preadolescent females with pathological anxiety

Pathological anxiety typically emerges during preadolescence and has been linked to alterations in white matter (WM) pathways. Because myelination is critical for efficient neuronal communication, characterizing associations between WM microstructure and symptoms may provide insights into pathophysiological mechanisms associated with childhood pathological anxiety. This longitudinal study examined 182 girls enrolled between the ages of 9-11 that were treatment-naïve at study entry: healthy controls (n = 49), subthreshold-anxiety disorders (AD) (n = 82), or meeting DSM-5 criteria for generalized, social, and/or separation ADs (n = 51), as determined through structured clinical interview. Anxiety severity was assessed with the Clinical Global Impression Scale and Screen for Child Anxiety and Related Emotional Disorders (SCARED). Participants (n = 182) underwent clinical, behavioral, and diffusion tensor imaging (DTI) assessments at study entry, and those with pathological anxiety (subthreshold-AD and AD, n = 133) were followed longitudinally for up to 3 additional years. Cross-sectional ANCOVAs (182 scans) examining control, subthreshold-AD, and AD participants found no significant relations between anxiety and DTI measurements. However, in longitudinal analyses of girls with pathological anxiety (343 scans), linear mixed-effects models demonstrated that increases in anxiety symptoms (SCARED scores) were associated with reductions in whole-brain fractional anisotropy, independent of age (Std. β (95% CI) = -0.06 (-0.09 to -0.03), F(1, 46.24) = 11.90, P = 0.001). Using a longitudinal approach, this study identified a dynamic, within-participant relation between whole-brain WM microstructural integrity and anxiety in girls with pathological anxiety. Given the importance of WM microstructure in modulating neural communication, this finding suggests the possibility that WM development could be a viable target in the treatment of anxiety-related psychopathology.

General additive models address statistical issues in diffusion MRI: An example with clinically anxious adolescents

Statistical models employed to test for group differences in quantized diffusion-weighted MRI white matter tracts often fail to account for the large number of data points per tract in addition to the distribution, type, and interdependence of the data. To address these issues, we propose the use of Generalized Additive Models (GAMs) and supply code and examples to aid in their implementation. Specifically, using diffusion data from 73 periadolescent clinically anxious and no-psychiatric-diagnosis control participants, we tested for group tract differences and show that a GAM allows for the identification of differences within a tract while accounting for the nature of the data as well as covariates and group factors. Further, we then used these tract differences to investigate their association with performance on a memory test. When comparing our high versus low anxiety groups, we observed a positive association between the left uncinate fasciculus and memory overgeneralization for negatively valenced stimuli. This same association was not evident in the right uncinate or anterior forceps. These findings illustrate that GAMs are well-suited for modeling diffusion data while accounting for various aspects of the data, and suggest that the adoption of GAMs will be a powerful investigatory tool for diffusion-weighted analyses.

Using diffusion MRI data acquired with ultra-high gradient strength to improve tractography in routine-quality data

The development of scanners with ultra-high gradient strength, spearheaded by the Human Connectome Project, has led to dramatic improvements in the spatial, angular, and diffusion resolution that is feasible for in vivo diffusion MRI acquisitions. The improved quality of the data can be exploited to achieve higher accuracy in the inference of both microstructural and macrostructural anatomy. However, such high-quality data can only be acquired on a handful of Connectom MRI scanners worldwide, while remaining prohibitive in clinical settings because of the constraints imposed by hardware and scanning time. In this study, we first update the classical protocols for tractography-based, manual annotation of major white-matter pathways, to adapt them to the much greater volume and variability of the streamlines that can be produced from today’s state-of-the-art diffusion MRI data. We then use these protocols to annotate 42 major pathways manually in data from a Connectom scanner. Finally, we show that, when we use these manually annotated pathways as training data for global probabilistic tractography with anatomical neighborhood priors, we can perform highly accurate, automated reconstruction of the same pathways in much lower-quality, more widely available diffusion MRI data. The outcomes of this work include both a new, comprehensive atlas of WM pathways from Connectom data, and an updated version of our tractography toolbox, TRActs Constrained by UnderLying Anatomy (TRACULA), which is trained on data from this atlas. Both the atlas and TRACULA are distributed publicly as part of FreeSurfer. We present the first comprehensive comparison of TRACULA to the more conventional, multi-region-of-interest approach to automated tractography, and the first demonstration of training TRACULA on high-quality, Connectom data to benefit studies that use more modest acquisition protocols.

Prenatal Exposure And Child brain and mental Health (PEACH) study: protocol for a cohort study of children and youth with prenatal alcohol exposure

INTRODUCTION

Fetal alcohol spectrum disorder (FASD), which is caused by prenatal alcohol exposure (PAE), affects an estimated 4% of North Americans, and is the most common preventable cause of intellectual disability. Mental health problems, including anxiety and depression, are experienced by nearly all individuals with FASD. However, there is very limited knowledge about effective mental health treatments for individuals with FASD; effective treatments are hindered in part due to a lack of understanding of the basic neurobiology underlying internalising disorders in youth with FASD.

METHODS AND ANALYSIS

The Prenatal Exposure And Child brain and mental Health (PEACH) study includes children aged 7-18 years. We will use longitudinal neuroimaging (anatomical T1-weighted, diffusion and passive viewing function MRI) and mental health assessments (Behaviour Assessment Scale for Children, Multi-dimensional Anxiety Scale for Children, Children's Depression Inventory (CDI-2), Kiddie Scale of Affective Disorders) to: (1) characterise brain development trajectories in youth with FASD, (2) determine whether brain alterations mediate increased anxiety and depression in youth with FASD and (3) identify baseline brain features that predict changes of anxiety and depression symptoms over the next 2 years. All of this will be done while considering sex and adverse postnatal experiences, which can significantly impact mental health and brain outcomes. This project will forge new understanding of FASD and mental health from a neurobiological perspective, highlighting key time periods (ie, sensitive windows) and brain regions (ie, that may be susceptible to neurostimulation), while identifying factors that predict individual trajectories of anxiety and depression symptoms.

ETHICS AND DISSEMINATION

This study was approved by the University of Calgary Conjoint Health Research Ethics Board and the University of Alberta Health Research Ethics Board. Study results will be disseminated in peer-reviewed journals, at relevant conferences and in conjunction with our knowledge mobilisation partners.

Disruption of functional and structural networks in first-episode, drug-naïve adolescents with generalized anxiety disorder

BACKGROUND

Individuals with generalized anxiety disorder (GAD) tend to worry exaggeratedly and uncontrollably about various daily routines. Previous studies have demonstrated that the GAD patients exhibited widespread alternations in both functional networks (FN) and structural networks (SN). However, the simultaneous alternations of the topological organization of FN, SN, as well as their couplings in GAD still remain unknown.

METHODS

Using multimodal approach, we constructed FN from resting-state functional magnetic imaging (R-fMRI) data and SN from diffusion magnetic resonance imaging (dMRI) data of 32 adolescent GAD patients and 25 healthy controls (HC). Graph theory analysis was employed to investigate the topological properties of FN, SN, and FN-SN coupling.

RESULTS

Compared to HC, the GAD patients showed disruptions in global (i.e., decreased clustering coefficient, global, and local efficiency) and subnetwork (i.e., reduced intermodular connections, rich club, and feeder connections) levels in FN. Abnormal global level properties (i.e., increased characteristic path length and reduced global efficiency) were also observed in SN. Altered FN-SN couplings in normalized characteristic path length and feeder connections were identified in the GAD patients. The identified network measures were correlated with anxiety severity in the GAD patients.

LIMITATIONS

The sample size of the current study is small and the cross-sectional nature can not infer causal relationship.

CONCLUSIONS

Our findings identified GAD-related topological alternations in both FN and SN, together with the couplings between FN and SN, providing us with a novel perspective for understanding the pathophysiological mechanisms of GAD.

Initial white matter connectivity differences between remitters and non-remitters of patients with panic disorder after 6 months of pharmacotherapy

Panic disorder (PD) is a harmful mental condition that causes relapsed and persistent impairment. In the treatment of PD, the prognosis for PD should be considered. However, the relationship between pharmacotherapy and biomarkers, for predicting a better response through neuroimaging, is a little known. The purpose of the present study was to examine whether there would be the initial white matter (WM) regions associated with the remission in 6 months. A total of 104 patients with PD were investigated in the study. After six months, there were 17 remission patients with PD and 81 non-remission patients. The Panic Disorder Severity Scale, Albany Panic and Phobia Questionnaire, Anxiety Sensitivity Inventory-Revised, Beck Anxiety Inventory, and Beck Depression Inventory were assessed for all patients at baseline. We compared the diffusion indices between remission and non-remission group at 6 months using Tract-Based Spatial Statistics. The results showed that the fractional anisotropy (FA) values were significantly higher in the non-remitter group compared with those in the remitter group in the WM regions, such as the posterior corona radiata and superior longitudinal fasciculus, at the 6 month evaluation. The logistic regression analysis with clinical symptom severity and FA values of the WM regions as covariates showed that FA values in those regions and the Beck Depression Inventory-II predicted poor remission. This study suggests that posterior corona radiata and superior longitudinal fasciculus are related to potential predictive factors of 6-month remission in patients with PD. WM regions associated with the long-term remission should be verified with further investigations.

White matter structural network disturbances in first-episode, drug-naïve adolescents with generalized anxiety disorder

BACKGROUND

Previous studies have suggested that individuals with generalized anxiety disorder (GAD) would show inefficient whole-brain communication and dysconnectivity in the fronto-parietal-subcortical sub-networks in the white matter (WM) structural network. However, these hypotheses have yet to be tested.

METHODS

Individual WM structural networks were constructed based on diffusion MRI data and deterministic tractography in 34 first-episode, medication-naïve adolescents with GAD and 27 healthy controls (HCs). Graph theory was applied to investigate the topological organization alterations of the structural network.

RESULTS

GAD patients showed disrupted small-world configurations (i.e., increased path length and decreased clustering coefficient) and hub organization (i.e., less connection strength in the feeder and local connections). A decreased connection strength was found in a GAD-related sub-network (mainly involving the frontal-subcortical circuits), which was able to distinguish GAD patients from HCs with higher accuracy (area under the curve of 0.96, sensitivity of 94%, specificity of 89%) than clinical scores and other topological alternations.

LIMITATIONS

The current study just compared GAD patients with HCs based on a small sample, leaving whether the alternations found here are specific to GAD still an open question. Future studies are recommended to recruit patients with other anxiety disorders (e.g., social anxiety disorder) and/or comorbid mood disorders to identify the GAD-specific WM alterations using a larger sample.

CONCLUSIONS

Our findings highlight the disruption of the topological organization of the whole-brain WM structural network (especially the frontal-subcortical circuits) in GAD, and suggest the potential of using structural connectivity of the GAD-related sub-network as a biomarker for GAD patients.

Nicotine Effects on White Matter Microstructure in Young Adults

OBJECTIVE

Nicotine use is widely prevalent among youth, and is associated with white matter microstructural changes as measured by diffusion tensor imaging (DTI). In adults, nicotine use is generally associated with lower fractional anisotropy (FA), but in adolescents/young adults (≤30 years), microstructure appears healthier, indicated by higher FA. This cross-sectional study examined associations between nicotine use and white matter microstructure using fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) in young adults.

METHODS

Fifty-three participants (18 nicotine users [10 female]/35 controls [17 female]) ages 18-25 underwent MRI scan, neuropsychological battery, toxicology screening, and drug use interview. Nicotine group associations with FA and MD were examined in various white matter tracts. In significant tracts, AD and RD were measured. Exploratory correlations were conducted between significant tracts and verbal memory and sustained attention/working memory performance.

RESULTS

Nicotine users exhibited significantly lower FA than controls in the left anterior thalamic radiation, left inferior longitudinal fasciculus, left superior longitudinal fasciculus-temporal, and left uncinate fasciculus. In these tracts, AD and RD did not differ, nor did MD differ in any tract. White matter quality was positively correlated with sustained attention/working memory performance.

CONCLUSIONS

Cigarette smoking may disrupt white matter microstructure. These results are consistent with adult studies, but inconsistent with adolescent/young adult studies, likely due to methodological and sample age differences. Further studies should examine longitudinal effects of nicotine use on white matter microstructure in a larger sample.

Image acquisition and quality assurance in the Boston Adolescent Neuroimaging of Depression and Anxiety study

The Connectomes Related to Human Diseases (CRHD) initiative was developed with the Human Connectome Project (HCP) to provide high-resolution, open-access, multi-modal MRI data to better understand the neural correlates of human disease. Here, we present an introduction to a CRHD project, the Boston Adolescent Neuroimaging of Depression and Anxiety (BANDA) study, which is collecting multimodal neuroimaging, clinical, and neuropsychological data from 225 adolescents (ages 14-17), 150 of whom are expected to have a diagnosis of depression and/or anxiety. Our transdiagnostic recruitment approach samples the full spectrum of depressed/anxious symptoms and their comorbidity, consistent with NIMH Research Domain Criteria (RDoC). We focused on an age range that is critical for brain development and for the onset of mental illness. This project sought to harmonize imaging sequences, hardware, and functional tasks with other HCP studies, although some changes were made to canonical HCP methods to accommodate our study population and questions. We present a thorough overview of our imaging sequences, hardware, and scanning protocol. We detail similarities and differences between this study and other HCP studies. We evaluate structural-, diffusion-, and functional-image-quality measures that may be influenced by clinical factors (e.g., disorder, symptomatology). Signal-to-noise and motion estimates from the first 140 adolescents suggest minimal influence of clinical factors on image quality. We anticipate enrollment of an additional 85 participants, most of whom are expected to have a diagnosis of anxiety and/or depression. Clinical and neuropsychological data from the first 140 participants are currently freely available through the National Institute of Mental Health Data Archive (NDA).

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 Relationship Between the Uncinate Fasciculus and Anxious Temperament Is Evolutionarily Conserved and Sexually Dimorphic

BACKGROUND

Anxious temperament (AT) is an early-life heritable trait that predisposes individuals to develop anxiety and depressive disorders. Our previous work in preadolescent children suggests alterations in the uncinate fasciculus (UF), the white matter tract that connects prefrontal with limbic regions, in boys with anxiety disorders. Here, using a nonhuman primate model of AT, we tested whether this sexually dimorphic finding is evolutionarily conserved and examined the extent to which heritable and environmental influences contribute to UF microstructure.

METHODS

Diffusion tensor images were collected in 581 young rhesus monkeys (1.89 ± 0.77 years old; 43.9% female). Using tract-based analyses, we assessed the relationship among AT, UF microstructure (as measured with fractional anisotropy), and sex. Heritability of tract microstructure was determined using oligogenic linkage analysis of this large multigenerational pedigree.

RESULTS

We predicted and found a negative relation between AT and UF fractional anisotropy in male but not female monkeys (AT × sex; p = .032, 1-tailed). Additionally, heritability analyses revealed that variation in UF fractional anisotropy was largely due to nonheritable factors (h² = 0.185, p = .077).

CONCLUSIONS

These results demonstrate a cross-species, male-specific relation between UF microstructure and anxiety and provide a potential substrate for anxiety-related prefrontal-limbic dysregulation. The heritability analyses point to the importance of environmental influences on UF microstructure, which could be important in mediating the nonheritable components of pathological anxiety. These findings have the potential to guide new treatment strategies for childhood anxiety disorders and further support the use of nonhuman primates as a translational model to discover mechanisms underlying the development of anxiety.

White Matter Microstructure in Youths With Conduct Disorder: Effects of Sex and Variation in Callous Traits

OBJECTIVE

Studies using diffusion tensor imaging (DTI) to investigate white matter (WM) microstructure in youths with conduct disorder (CD) have reported disparate findings. We investigated WM alterations in a large sample of youths with CD, and examined the influence of sex and callous-unemotional (CU) traits.

METHOD

DTI data were acquired from 124 youths with CD (59 female) and 174 typically developing (TD) youths (103 female) 9 to 18 years of age. Tract-based spatial statistics tested for effects of diagnosis and sex-by-diagnosis interactions. Associations with CD symptoms, CU traits, a task measuring impulsivity, and the impact of comorbidity, and age- and puberty-related effects were examined.

RESULTS

Youths with CD exhibited higher axial diffusivity in the corpus callosum and lower radial diffusivity and mean diffusivity in the anterior thalamic radiation relative to TD youths. Female and male youths with CD exhibited opposite changes in the left hemisphere within the internal capsule, fornix, posterior thalamic radiation, and uncinate fasciculus. Within the CD group, CD symptoms and callous traits exerted opposing influences on corpus callosum axial diffusivity, with callous traits identified as the unique clinical feature predicting higher axial diffusivity and lower radial diffusivity within the corpus callosum and anterior thalamic radiation, respectively. In an exploratory analysis, corpus callosum axial diffusivity partially mediated the association between callous traits and impulsive responses to emotional faces. Results were not influenced by symptoms of comorbid disorders, and no age- or puberty-related interactions were observed.

CONCLUSION

WM alterations within the corpus callosum represent a reliable neuroimaging marker of CD. Sex and callous traits are important factors to consider when examining WM in CD.

Systematic review and meta-analyses of neural structural and functional differences in generalized anxiety disorder and healthy controls using magnetic resonance imaging

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PFC-amygdala FC is altered in GAD, indicating top-down processing deficits.

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GAD had reduced activity for emotion regulation and working memory in the culmen.

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Salience, default, and central executive nodes have altered structure and function.

Objective

To compare structure, functional connectivity (FC) and task-based neural differences in subjects with generalized anxiety disorder (GAD) compared to healthy controls (HC).

Methods

The Embase, Ovid Medline, PsycINFO, Scopus, and Web of Science databases were searched from inception until March 12, 2018. Two reviewers independently screened titles, abstracts, and full-text articles. Data were extracted from records directly contrasting GAD and HC that included structure (connectivity and local indices such as volume, etc.), FC, or task-based magnetic resonance imaging data. Meta-analyses were conducted, as applicable, using AES-SDM software.

Results

The literature search produced 4,645 total records, of which 85 met the inclusion criteria for the systematic review. Records included structural (n = 35), FC (n = 33), and task-based (n = 42) findings. Meta-analyses were conducted on voxel-based morphometry and task-based results.

Discussion

The systematic review confirms and extends findings from previous reviews. Although few whole-brain resting state studies were conducted, key nodes of resting state networks have altered physiology: the hippocampus (default network), ACC and amygdala (salience network), have reduced volume, and the dlPFC (central executive network) and ACC have reduced FC with the amygdala in GAD. Nodes in the sensorimotor network are also altered with greater pre- and postcentral volume, reduced supplementary motor area volume, and reduced FC in anterior and increased FC in posterior cerebellum.

Conclusions

Despite limitations due to sample size, the meta-analyses highly agree with the systematic review and provide evidence of widely distributed neural differences in subjects with GAD, compared to HC. Further research optimized for meta-analyses would greatly improve large-scale comparisons.

Individualized prediction of dispositional worry using white matter connectivity

BACKGROUND

Excessive worry is a defining feature of generalized anxiety disorder and is present in a wide range of other psychiatric conditions. Therefore, individualized predictions of worry propensity could be highly relevant in clinical practice, with respect to the assessment of worry symptom severity at the individual level.

METHODS

We applied a multivariate machine learning approach to predict dispositional worry based on microstructural integrity of white matter (WM) tracts.

RESULTS

We demonstrated that the machine learning model was able to decode individual dispositional worry scores from microstructural properties in widely distributed WM tracts (mean absolute error = 10.46, p < 0.001; root mean squared error = 12.82, p < 0.001; prediction R2 = 0.17, p < 0.001). WM tracts that contributed to worry prediction included the posterior limb of internal capsule, anterior corona radiate, and cerebral peduncle, as well as the corticolimbic pathways (e.g. uncinate fasciculus, cingulum, and fornix) already known to be critical for emotion processing and regulation.

CONCLUSIONS

The current work thus elucidates potential neuromarkers for clinical assessment of worry symptoms across a wide range of psychiatric disorders. In addition, the identification of widely distributed pathways underlying worry propensity serves to better improve the understanding of the neurobiological mechanisms associated with worry.

Attentional control abnormalities in posttraumatic stress disorder: Functional, behavioral, and structural correlates

BACKGROUND

Attentional disruptions are common in PTSD, but findings across neuropsychological and neuroimaging studies have been variable. Few PTSD studies have investigated abnormalities in attention networks using a multi-modal imaging approach and attentional tasks that include emotionally-salient images. This study combined a behavioral task that included these images (emotional Stroop) with functional and structural neuroimaging (fMRI and diffusion tensor imaging; DTI) methods to comprehensively investigate attentional control abnormalities in a highly-traumatized civilian sample.

METHODS

48 traumatized women with and without PTSD received clinical assessments, fMRI and DTI. During fMRI, the Affective Stroop (AS), an attentional control task that includes emotionally-salient distractor images (trauma-relevant, positive, neutral) and variable task demands, was administered.

RESULTS

In response to more difficult AS trials, participants with PTSD demonstrated lower activation in the dorsal and rostral anterior cingulate cortex and greater activation in the insula. This group also showed comparatively poorer performance on positive AS distractor trials, even after adjusting for trauma exposure. Performance on these trials inversely correlated with structural integrity of the cingulum bundle and uncinate fasciculus.

CONCLUSIONS

Even after adjusting for trauma exposure, participants with PTSD showed worse performance on an attentional control task in the context of emotional stimuli. They also showed relatively lower cognitive control network activation and greater salience network activation. Fronto-parietal and fronto-limbic white matter connectivity corresponded with AS performance. Our findings indicate that attentional control impairments in PTSD are most evident in the context of emotional cues, and are related to decrements in function and structure of cognitive control and salience networks.

Psychiatric disorders in multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is characterized by a large spectrum of symptoms, involving all functional systems. Psychiatric symptoms are common in people with MS (pwMS) having an important impact on quality of life and on some features of MS (fatigue, sleep, disability, adherence to disease-modifying drugs). The main psychiatric disturbances in MS are depressive, bipolar, anxiety, schizophrenic and obsessive-compulsive syndromes.

METHODS

Literature search for original articles and review in the databases, including PubMed and Scopus from 1959 to 2019.

RESULTS AND CONCLUSION

Studies answering the aim of this review were selected and reported. Epidemiological and clinical aspects of psychiatric syndromes (PS) in MS as well as self-report diagnostic scales and radiological correlates of PS in MS are described. Moreover, some radiological studies about primary psychiatric disorders (PD) are reported to underline how gray matter atrophy, white matter abnormalities and corpus callosum involvement in these diseases, as features in common with MS, may explain the more frequent occurrence of PD in MS than in the general population.

Multimodal evidence for delayed threat extinction learning in adolescence and young adulthood

Previous research in rodents and humans points to an evolutionarily conserved profile of blunted threat extinction learning during adolescence, underpinned by brain structures such as the amygdala and medial prefrontal cortex (mPFC). In this study, we examine age-related effects on the function and structural connectivity of this system in threat extinction learning in adolescence and young adulthood. Younger age was associated with greater amygdala activity and later engagement of the mPFC to learned threat cues as compared to safety cues. Furthermore, greater structural integrity of the uncinate fasciculus, a white matter tract that connects the amygdala and mPFC, mediated the relationship between age and mPFC engagement during extinction learning. These findings suggest that age-related changes in the structure and function of amygdala-mPFC circuitry may underlie the protracted maturation of threat regulatory processes.

Structural and functional neuroimaging studies in generalized anxiety disorder: a systematic review

OBJECTIVES

Brain imaging studies carried out in patients suffering from generalized anxiety disorder (GAD) have contributed to better characterize the pathophysiological mechanisms underlying this disorder. The present study reviews the available functional and structural brain imaging evidence on GAD, and suggests further strategies for investigations in this field.

METHODS

A systematic literature review was performed in PubMed, PsycINFO, and Google Scholar, aiming to identify original research evaluating GAD patients with the use of structural and functional magnetic resonance imaging as well as diffusion tensor imaging.

RESULTS

The available studies have shown impairments in ventrolateral and dorsolateral prefrontal cortex, anterior cingulate, posterior parietal regions, and amygdala in both pediatric and adult GAD patients, mostly in the right hemisphere. However, the literature is often tentative, given that most studies have employed small samples and included patients with comorbidities or in current use of various medications. Finally, different methodological aspects, such as the type of imaging equipment used, also complicate the generalizability of the findings.

CONCLUSIONS

Longitudinal neuroimaging studies with larger samples of both juvenile and adult GAD patients, as well as at risk individuals and unaffected relatives, should be carried out in order to shed light on the specific biological signature of GAD.

Disrupted interhemispheric resting-state functional connectivity and structural connectivity in first-episode, treatment-naïve generalized anxiety disorder

BACKGROUND

Aberrant functional and structural connectivity are considered to be involved in the underlying neural mechanism of generalized anxiety disorder (GAD). However, alterations in functional and structural interactions between the bilateral hemispheres are rarely examined. The current study aimed to characterized interhemispheric resting-state functional connectivity and white matter microstructural integrity of the corpus callosum in patients with GAD.

METHODS

Resting-state Blood oxygen level-dependent and diffusion tensor image were acquired for patients with GAD and healthy subjects. The two groups were matched in age, gender, education years. The voxel-mirrored homotopic connectivity (VMHC) of whole brain and white matter integrity of the corpus callosum (CC) were compared between the two groups. Their correlations with clinical measures were further performed.

RESULTS

Compare to controls, decreased resting-state VMHC were found in the precentral gyrus, middle cingulate gyrus and insula/putamen in patients with GAD. No regions of increased VMHC were detected in GAD. Compared to controls, GAD patients showed decreased fractional anisotropy (FA) values in CC2. In GAD group, further Pearson's correlation analyses showed that VMHC of the midcingulate gyrus positively correlated with FA of CC2, FA of CC2 negatively correlated with anxiety severity. Further mediation analyses demonstrated that attenuated VMHC in bilateral midcingulate gyrus partly mediated the association between white matter integrity of CC2 sub-region and anxiety severity.

CONCLUSION

Our findings suggested impairment of interhemispheric coordination in GAD. Moreover, disrupted interhemispheric connectivity correlated with anxiety severity in GAD. Our findings provided a novel clue about the neural mechanism of GAD, and may contribute to further deep exploration and treatment of GAD.

LIMITATIONS

The study was lack of comparison with non-GAD anxiety disorders.

Posterior limb of the internal capsule predicts poor quality of life in patients with Parkinson's disease: connectometry approach

Psychiatric symptoms and motor impairment are major contributions to the poor quality of life in patients with Parkinson's disease (PD). Here, we applied a novel diffusion-weighted imaging approach, diffusion MRI connectometry, to investigate the correlation of quality of life, evaluated by Parkinson's Disease Questionnaire (PDQ39) with the white matter structural connectivity in 27 non-demented PD patients (disease duration of 5.3 ± 2.9 years, H and Y stage = 1.5 ± 0.6, UPDRS-III = 13.7 ± 6.5, indicating unilateral and mild motor involvement). The connectometry analysis demonstrated bilateral posterior limbs of the internal capsule (PLIC) with increased connectivity related to the higher quality of life (FDR = 0.027) in a multiple regression model. The present study suggests for the first time a neural basis of the quality of life in PD in the light of major determinants of poor quality of life in these patients: anxiety, depression, apathy and motor impairment. Results in our sample of non-demented PD patients with relatively mild motor impairment and no apparent sign of depression/anxiety also identify a unique and inexplicable association of the PLIC to the quality of life in PD patients.

Translating Developmental Neuroscience to Understand Risk for Psychiatric Disorders

The transition from childhood to adulthood represents the developmental time frame in which the majority of psychiatric disorders emerge. Recent efforts to identify risk factors mediating the susceptibility to psychopathology have led to a heightened focus on both typical and atypical trajectories of neural circuit maturation. Mounting evidence has highlighted the immense neural plasticity apparent in the developing brain. Although in many cases adaptive, the capacity for neural circuit alteration also induces a state of vulnerability to environmental perturbations, such that early-life experiences have long-lasting implications for cognitive and emotional functioning in adulthood. The authors outline preclinical and neuroimaging studies of normative human brain circuit development, as well as parallel efforts covered in this issue of the Journal, to identify brain circuit alterations in psychiatric disorders that frequently emerge in developing populations. Continued translational research into the interactive effects of neurobiological development and external factors will be crucial for identifying early-life risk factors that may contribute to the emergence of psychiatric illness and provide the key to optimizing treatments.

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.

Orbitofrontal connectivity is associated with depression and anxiety in marijuana-using adolescents

BACKGROUND

Prevalence of marijuana (MJ) use among adolescents has been on the rise. MJ use has been reported to impact several brain regions, including frontal regions such as the orbitofrontal cortex (OFC). The OFC is involved in emotion regulation and processing and has been associated with symptoms of depression and anxiety. Therefore, we hypothesized that adolescent MJ users would show disruptions in OFC connectivity compared with healthy adolescents (HC) which would be associated with symptoms of mood and anxiety.

METHODS

43 MJ-using and 31 HC adolescents completed clinical measures including the Hamilton Anxiety Scale (HAM-A) and Hamilton Depression Rating Scale (HAM-D). Resting-state functional magnetic resonance imaging data was also acquired for all participants.

RESULTS

In MJ users, increased depressive symptoms were associated with increased connectivity between the left OFC and left parietal regions. In contrast, lower ratings of anxiety were associated with increased connectivity between right and left OFC and right occipital and temporal regions. These findings indicate significant differences in OFC connectivity in MJ-using adolescents, which correlated with mood/anxiety.

LIMITATIONS

Future studies with an increased number of female participants is required to address potential sex differences in connectivity patterns related to symptoms of depression and anxiety.

CONCLUSIONS

This study highlights the association between OFC connectivity, MJ use, and symptoms of depression and anxiety in adolescents. These findings provide further insight into understanding the neural correlates that modulate the relationship between comorbid MJ use and mood disorders and could potentially help us better develop preventive and treatment measures.

Resilience to Risk for Psychopathology: The Role of White Matter Microstructural Development in Adolescence

BACKGROUND

One major risk factor for the development of psychopathology is a family history of psychopathology (FHP). Cross-sectional studies have shown that FHP is associated with alterations in white matter microstructure in adolescents without current psychopathology; however, whether these associations persist throughout adolescence, particularly in those who remain resilient to developing psychopathology, is unclear.

METHODS

Sixty-six adolescents underwent diffusion-weighted imaging at baseline (12-16 years of age) and at one or two follow-up visits (142 total scans). Adolescents' parents completed a modified Family History Assessment Module to calculate FHP density (FHPD) based on familial alcohol use, substance use, and major depressive, generalized anxiety, substance-induced mood, and antisocial personality disorders. The relationship between FHPD and white matter microstructural development was examined using multilevel modeling.

RESULTS

FHPD was associated with significant alterations in white matter microstructure at baseline; in the bilateral superior corona radiata and left superior longitudinal fasciculus, these effects were transient (FHPD was associated with altered white matter microstructure only in early adolescence), while effects in the posterior limb of the internal capsule were persistent. Associations between FHPD and white matter microstructure in the body of the corpus callosum emerged later in adolescence.

CONCLUSIONS

This prospective, longitudinal study provides novel information indicating that the association between FHP and white matter microstructure previously observed in adolescents is transient in most regions but may persist into late adolescence in other regions, despite current resilience to developing psychopathology. Future studies are necessary to determine if these persistent alterations are associated with onset of psychopathology later in life.

Cerebral White Matter Changes in Young Healthy Individuals With High Trait Anxiety: A Tract-Based Spatial Statistics Study

Background: Abnormalities in prespecified and empirical white matter tracts in young patients with anxiety-related disorders have been reported in some diffusion tensor imaging (DTI) studies. However, with few literatures examining the association between the integrity of whole brain white matter and trait anxiety levels in the non-clinical populations, whether white matter changes arise in young healthy individuals with high trait anxiety remains unknown.

Methods: We examined whole brain white matter alterations in young healthy individuals with high anxiety but without history of neurological or psychiatric disorders via DTI technology. Group comparison of tract-based spatial statistics (TBSS) was performed to investigate the microstructural diffusion alterations in 38 high anxious subjects in comparison with 34 low anxious subjects matched with age, gender, and degree of education. These analyses controlled for depression to establish specificity to trait anxiety.

Results: Young healthy subjects with high trait anxiety had significantly decreased fractional anisotropy (FA) values in multiple clusters, including corona radiate (CR), anterior thalamic radiation (ATR), inferior fronto-occipital fasciculus (IFOF), bilaterally, body, genu, and splenium of corpus callosum (CC) and forceps minor, compared with low trait anxious subjects. For the abnormal FA regions, the other diffusion metrics were also altered slightly.

Conclusions: Non-clinical individuals with high anxiety already have white matter alterations in the thalamus-cortical circuit and some emotion-related areas that were widely reported in anxiety-related disorders. The altered white matter may be a vulnerability marker in individuals at high risk of clinical anxiety. These findings can deepen our understanding of the pathological mechanism of anxiety and further support the need for preventive interventions in high anxiety individuals.

Amygdala-orbitofrontal structural and functional connectivity in females with anxiety disorders, with and without a history of conduct disorder

Conduct disorder (CD) and anxiety disorders (ADs) are often comorbid and both are characterized by hyper-sensitivity to threat, and reduced structural and functional connectivity between the amygdala and orbitofrontal cortex (OFC). Previous studies of CD have not taken account of ADs nor directly compared connectivity in the two disorders. We examined three groups of young women: 23 presenting CD and lifetime AD; 30 presenting lifetime AD and not CD; and 17 with neither disorder (ND). Participants completed clinical assessments and diffusion-weighted and resting-state functional MRI scans. The uncinate fasciculus was reconstructed using tractography and manual dissection, and structural measures extracted. Correlations of resting-state activity between amygdala and OFC seeds were computed. The CD + AD and AD groups showed similarly reduced structural integrity of the left uncinate compared to ND, even after adjusting for IQ, psychiatric comorbidity, and childhood maltreatment. Uncinate integrity was associated with harm avoidance traits among AD-only women, and with the interaction of poor anger control and anxiety symptoms among CD + AD women. Groups did not differ in functional connectivity. Reduced uncinate integrity observed in CD + AD and AD-only women may reflect deficient emotion regulation in response to threat, common to both disorders, while other neural mechanisms determine the behavioral response.

The neurobiology of brain recovery from traumatic stress: A longitudinal DTI study

BACKGROUND

Previous studies demonstrated decreased brain microstructure integrity in people that were exposed to extreme life stress but did not meet posttraumatic stress disorder (PTSD) diagnostic criteria. It is unclear how the brain recovers from traumatic stress in these trauma-exposed non-PTSD people (TENP).

METHODS

Twenty-two TENP individuals were recruited from the most affected area of Wenchuan quake, and scanned twenty-five days after the quake and at a two-year follow-up. Tract-based spatial statistics was used to examine brain microstructure changes over the two years. Correlation analyses were conducted to investigate relationships between brain microstructure changes and both stress recovery and demographic factors. To assess DTI stability, fifteen healthy subjects were scanned twice in a year and analysed similarly.

RESULTS

Significantly increased fractional anisotropy (FA) was found in the left posterior limb of internal capsule, left superior and posterior corona radiata (SCR and PCR), and left external capsule. The FA increase of these regions was primarily a result of radial diffusivity reduction. Recovery in symptoms was positively correlated with FA increase of SCR. Changes were related to participant age and sex. No DTI measures were changed for the healthy subjects.

LIMITATIONS

Generalizability of the findings was constrained by the relatively small sample size.

CONCLUSIONS

The TENP individuals showed a recovery from the trauma over the follow-up, and that was accompanied with increased brain microstructure integrity in fiber tracts primarily involving corticostriatal networks. These changes may contribute to the psychological resilience to a severe life stress that led to PTSD in quake victims. In particular，this study adds to Psychoradiology, which is a promising subspecialty for clinical radiology focusing on psychiatric disorders.

Aberrant Functional Network Connectivity as a Biomarker of Generalized Anxiety Disorder

Neural disruptions during emotion regulation are common of generalized anxiety disorder (GAD). Identifying distinct functional and effective connectivity patterns in GAD may provide biomarkers for their diagnoses. This study aims to investigate the differences of features of brain network connectivity between GAD patients and healthy controls (HC), and to assess whether those differences can serve as biomarkers to distinguish GAD from controls. Independent component analysis (ICA) with hierarchical partner matching (HPM-ICA) was conducted on resting-state functional magnetic resonance imaging data collected from 20 GAD patients with medicine-free and 20 matched HC, identifying nine highly reproducible and significantly different functional brain connectivity patterns across diagnostic groups. We then utilized Granger causality (GC) to study the effective connectivity between the regions that identified by HPM-ICA. The linear discriminant analysis was finally used to distinguish GAD from controls with these measures of neural connectivity. The GAD patients showed stronger functional connectivity in amygdala, insula, putamen, thalamus, and posterior cingulate cortex, but weaker in frontal and temporal cortex compared with controls. Besides, the effective connectivity in GAD was decreased from the cortex to amygdala and basal ganglia. Applying the ICA and GC features to the classifier led to a classification accuracy of 87.5%, with a sensitivity of 90.0% and a specificity of 85.0%. These findings suggest that the presence of emotion dysregulation circuits may contribute to the pathophysiology of GAD, and these aberrant brain features may serve as robust brain biomarkers for GAD.

An Effective Method to Identify Adolescent Generalized Anxiety Disorder by Temporal Features of Dynamic Functional Connectivity

Generalized anxiety disorder (GAD) is one of common anxiety disorders in adolescents. Although adolescents with GAD are thought to be at high risk for other mental diseases, the disease-specific alterations have not been adequately explored. Recent studies have revealed the abnormal functional connectivity (FC) in adolescents with GAD. Most previous researches have investigated the static FC which ignores the fluctuations of FC over time and focused on the structures of “fear circuit”. To figure out the alterations of dynamic FC caused by GAD and the possibilities of dynamic FC as biomarkers, we propose an effective approach to identify adolescent GAD using temporal features derived from dynamic FC. In our study, the instantaneous synchronization of pairwise signals was estimated as dynamic FC. The Hurst exponent (H) and variance, indicating regularity and variable degree of a time series respectively, were calculated as temporal features of dynamic FC. By leave-one-out cross-validation (LOOCV), a relatively high accuracy of 88.46% could be achieved when H and variance of dynamic FC were combined as features. In addition, we identified the disease-related regions, including regions belonging to default mode (DM) and cerebellar networks. The results suggest that temporal features of dynamic FC could achieve a clinically acceptable diagnostic power and serve as biomarkers of adolescent GAD. Furthermore, our work could be helpful in understanding the pathophysiological mechanism of adolescent GAD.

Development of White Matter Microstructure and Intrinsic Functional Connectivity Between the Amygdala and Ventromedial Prefrontal Cortex: Associations With Anxiety and Depression

BACKGROUND

Connectivity between the amygdala and ventromedial prefrontal cortex (vmPFC) is compromised in multiple psychiatric disorders, many of which emerge during adolescence. To identify to what extent the deviations in amygdala-vmPFC maturation contribute to the onset of psychiatric disorders, it is essential to characterize amygdala-vmPFC connectivity changes during typical development.

METHODS

Using an accelerated cohort longitudinal design (1-3 time points, 10-25 years old, n = 246), we characterized developmental changes of the amygdala-vmPFC subregion functional and structural connectivity using resting-state functional magnetic resonance imaging and diffusion-weighted imaging.

RESULTS

Functional connectivity between the centromedial amygdala and rostral anterior cingulate cortex (rACC), anterior vmPFC, and subgenual cingulate significantly decreased from late childhood to early adulthood in male and female subjects. Age-associated decreases were also observed between the basolateral amygdala and the rACC. Importantly, these findings were replicated in a separate cohort (10-22 years old, n = 327). Similarly, structural connectivity, as measured by quantitative anisotropy, significantly decreased with age in the same regions. Functional connectivity between the centromedial amygdala and the rACC was associated with structural connectivity in these same regions during early adulthood (22-25 years old). Finally, a novel time-varying coefficient analysis showed that increased centromedial amygdala-rACC functional connectivity was associated with greater anxiety and depression symptoms during early adulthood, while increased structural connectivity in centromedial amygdala-anterior vmPFC white matter was associated with greater anxiety/depression during late childhood.

CONCLUSIONS

Specific developmental periods of functional and structural connectivity between the amygdala and the prefrontal systems may contribute to the emergence of anxiety and depressive symptoms and may play a critical role in the emergence of psychiatric disorders in adolescence.

Anxiety-related experience-dependent white matter structural differences in adolescence: A monozygotic twin difference approach

Anxiety is linked to deficits in structural and functional connectivity between limbic structures and pre-frontal cortices. We employed a monozygotic (MZ) twin difference design to examine the relationship between structural characteristics of the uncinate fasciculus (UF) measured by Diffusion Tensor Imaging (DTI) and anxiety symptoms in a sample of N = 100 monozygotic (genetically identical), adolescent twins. The MZ difference design allowed us focus on environmental factors that vary within twin pairs while controlling for genetic and environmental factors shared by twin pairs. Twins aged 13-18 years reported on symptoms of generalized anxiety and social phobia prior to participating in a neuroimaging visit. Regions of interest from the JHU ICBM atlas, including uncinate fasciculus and sagittal stratum as a control tract, were registered to the study template. We incorporated multiple diffusion tensor measures to characterize the white matter differences. Within twin pairs, the more anxious twin exhibited decreased fractional anisotropy (t = -2.22, p = 0.032) and axial diffusivity (t = -2.38, p = 0.022) in the left UF compared to the less anxious twin, controlling for age and gender. This study demonstrated the feasibility and advantages of adopting the MZ twin design for DTI measures in neuroimaging research.

Functional and morphological alterations associated with working memory dysfunction in patients with generalized anxiety disorder

Background Generalized anxiety disorder (GAD) has been related to functional brain activities and structural brain abnormalities. Purpose To investigate the neural mechanism on working memory dysfunction in patients with GAD in terms of the combined functional and morphological brain abnormalities. Material and Methods Patients with GAD and healthy controls matched for age, sex, and education level underwent high-resolution T1-weighted (T1W) magnetic resonance imaging (MRI) and functional MRI (fMRI). In this study, fMRI and voxel-based morphometry (VBM) were used for assessing the differential brain activation patterns, as well as for comparing the morphological alterations between the two groups. Results In response to the neutral distractors, the patients showed significantly lower activities in the regions of the fusiform gyrus (FuG), superior parietal gyrus (SPG), precuneus (PCu), superior occipital gyrus (SOG), lingual gyrus (LiG), cuneus (Cun), calcarine cortex (CaC), parahippocampal gyrus (PHG) and cerebellar cortex (Cb) compared to the controls. In response to the anxiety-inducing distractors, the patients showed significantly higher activity in the hippocampus and lower activities in the regions of the dorsolateral prefrontal cortex (DLPFC), FuG, SPG, PCu, SOG, and Cb. Also, the patients showed a significant reduction of the white matter volumes in the DLPFC, anterior limb of the internal capsule (ALIC) and midbrain. Conclusion This study provides the first evidence for the association between the morphometric alterations and functional deficit in the working memory processing with the neutral and anxiety-inducing distractors in GAD patients. These findings would be helpful to understand the neural mechanisms on working memory impairment in connection with GAD symptoms.

Abnormalities in gray and white matter volumes associated with explicit memory dysfunction in patients with generalized anxiety disorder

Background The neuroanatomical abnormalities associated with behavioral dysfunction on explicit memory in patients generalized anxiety disorder (GAD) have not yet been clearly identified. Purpose To investigate the regional gray matter (GM) and white matter (WM) volume alterations over the whole brain in patients with GAD, as well as the correlation between the brain structural abnormality and explicit memory dysfunction. Material and Methods Twenty patients with GAD and 20 healthy controls matched for age, sex, and education level underwent high-resolution T1-weighted magnetic resonance imaging (MRI). The participants performed the explicit memory tasks with the neutral and anxiety-inducing words. Results Patients with GAD showed significantly reduced GM volumes in the midbrain (MB), thalamus, hippocampus (Hip), insula, and superior temporal gyrus (STG); and reduced WM volumes in the MB, anterior limb of the internal capsule (ALIC), dorsolateral prefrontal cortex (DLPFC), and precentral gyrus (PrG). It is important to note that the GM volume of the Hip and the WM volume of the DLPFC were positively correlated with the recognition accuracy (%) in the explicit memory tasks with neutral and anxiety-inducing words, respectively. On the other hand, the WM volume of the PrG was negatively correlated with the reaction time in the same memory tasks. Conclusion This study demonstrated the regional volume changes on whole-brain GM and WM and the correlation between the brain structural alteration and explicit memory dysfunction in GAD patients. These findings would be helpful to understand the association between the brain structure abnormality and the functional deficit in the explicit memory in GAD.