A pilot study of amygdala volumes in pediatric generalized anxiety disorder

Exploring volumetric abnormalities in subcortical L-HPA axis structures in pediatric generalized anxiety disorder

BACKGROUND

Pediatric generalized anxiety disorder (GAD) is debilitating and increasingly prevalent, yet its etiology remains unclear. Some believe the disorder to be propagated by chronic dysregulation of the limbic-hypothalamic-pituitary-adrenal (L-HPA) axis, but morphometric studies of implicated subcortical areas have been largely inconclusive. Recognizing that certain subcortical subdivisions are more directly involved in L-HPA axis functioning, this study aims to detect specific abnormalities in these critical areas.

METHODS

Thirty-eight MRI scans of preschool children with (n = 15) and without (n = 23) GAD underwent segmentation and between-group volumetric comparisons of the basolateral amygdala (BLA), ventral hippocampal subiculum (vSC), and mediodorsal medial magnocellular (MDm) area of the thalamus.

RESULTS

Children with GAD displayed significantly larger vSC compared to healthy peers, F(1, 31) = 6.50, pFDR = .048. On average, children with GAD presented with larger BLA and MDm, Fs(1, 31) ≥ 4.86, psFDR ≤ .054. Exploratory analyses revealed right-hemispheric lateralization of all measures, most notably the MDm, F(1, 31) = 8.13, pFDR = .024, the size of which scaled with symptom severity, r = .83, pFDR = .033.

CONCLUSION

The BLA, vSC, and MDm are believed to be involved in the regulation of anxiety and stress, both individually and collectively through the excitation and inhibition of the L-HPA axis. All were found to be enlarged in children with GAD, perhaps reflecting hypertrophy related to hyperexcitability, or early neuronal overgrowth. Longitudinal studies should investigate the relationship between these early morphological differences and the long-term subcortical atrophy previously observed.

Brain volumes, behavioral inhibition, and anxiety disorders in children: results from the adolescent brain cognitive development study

BACKGROUND

Magnetic resonance imaging (MRI) studies have identified brain changes associated with anxiety disorders (ADs), but the results remain mixed, particularly at a younger age. One key predictor of ADs is behavioral inhibition (BI), a childhood tendency for high avoidance of novel stimuli. This study aimed to evaluate the relationships between candidate brain regions, BI, and ADs among children using baseline data from the Adolescent Brain Cognitive Development (ABCD) study.

METHODS

We analyzed global and regional brain volumes of 9,353 children (9-10 years old) in relation to BI and current ADs, using linear mixed models accounting for family clustering and important demographic and socioeconomic covariates. We further investigated whether and how past anxiety was related to brain volumes.

RESULTS

Among included participants, 249 (2.66%) had a current AD. Larger total white matter (Beta = -0.152; 95% CI [-0.281, -0.023]), thalamus (Beta = -0.168; 95% CI [-0.291, -0.044]), and smaller hippocampus volumes (Beta = 0.094; 95% CI [-0.008, 0.196]) were associated with lower BI scores. Amygdala volume was not related to BI. Larger total cortical (OR = 0.751; 95% CI [0.580;0.970]), amygdala (OR = 0.798; 95%CI [0.666;0.956]), and precentral gyrus (OR = 0.802; 95% CI [0.661;0.973]) volumes were associated with lower odds of currently having ADs. Children with past ADs had smaller total white matter and amygdala volumes.

CONCLUSIONS

The results show associations between brain volumes and both BI and ADs at an early age. Importantly, results suggest that ADs and BI have different neurobiological correlates and that earlier occurrences of ADs may influence brain structures related to BI and ADs, motivating research that can better delineate the similarities and divergence in the neurobiological underpinnings and building blocks of BI and ADs across their development in early life.

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.

Transdiagnostic symptom of depression and anxiety associated with reduced gray matter volume in prefrontal cortex

Dimensional models of psychopathology may provide insight into mechanisms underlying comorbid depression and anxiety and improve specificity and sensitivity of neuroanatomical findings. The present study is the first to examine neural structure alterations using the empirically derived Tri-level Model. Depression and anxiety symptoms of 269 young adults were assessed using the Tri-level Model dimensions: General Distress (transdiagnostic depression and anxiety symptoms), Anhedonia-Apprehension (relatively specific depression symptoms), and Fears (specific anxiety symptoms). Using structural MRI, gray matter volumes were extracted for emotion generation (amygdala, nucleus accumbens) and regulation (orbitofrontal, ventrolateral, and dorsolateral prefrontal cortex) regions, often implicated in depression and anxiety. Each Tri-level symptom was regressed onto each region of interest, separately, adjusting for relevant covariates. General Distress was significantly associated with smaller gray matter volumes in bilateral orbitofrontal cortex and ventrolateral prefrontal cortex, independent of Anhedonia-Apprehension and Fears symptom dimensions. These results suggests that prefrontal alterations are associated with transdiagnostic dysphoric mood common across depression and anxiety, rather than unique symptoms of these disorders. Additionally, no regions of interest were associated with Anhedonia-Apprehension or Fears, highlighting the importance of studying transdiagnostic features of depression and anxiety. This has implications for understanding mechanisms of and interventions for depression and anxiety.

Contribution of the serotonergic system to developmental brain abnormalities in autism spectrum disorder

This review highlights a key role of the serotonergic system in brain development and in distortions of normal brain development in early stages of fetal life resulting in cascades of abnormalities, including defects of neurogenesis, neuronal migration, neuronal growth, differentiation, and arborization, as well as defective neuronal circuit formation in the cortex, subcortical structures, brainstem, and cerebellum of autistic subjects. In autism, defects in regulation of neuronal growth are the most frequent and ubiquitous developmental changes associated with impaired neuron differentiation, smaller size, distorted shape, loss of spatial orientation, and distortion of cortex organization. Common developmental defects of the brain in autism include multiregional focal dysplastic changes contributing to local neuronal circuit distortion, epileptogenic activity, and epilepsy. There is a discrepancy between more than 500 reports demonstrating the contribution of the serotonergic system to autism's behavioral anomalies, highlighted by lack of studies of autistic subjects' brainstem raphe nuclei, the center of brain serotonergic innervation, and of the contribution of the serotonergic system to the diagnostic features of autism spectrum disorder (ASD). Discovery of severe fetal brainstem auditory system neuronal deficits and other anomalies leading to a spectrum of hearing deficits contributing to a cascade of behavioral alterations, including deficits of social and verbal communication in individuals with autism, is another argument to intensify postmortem studies of the type and topography of, and the severity of developmental defects in raphe nuclei and their contribution to abnormal brain development and to the broad spectrum of functional deficits and comorbid conditions in ASD.

Maternal prenatal lead levels and neonatal brain volumes: Testing moderations by maternal depressive symptoms and family income

There is considerable evidence that prenatal lead exposure is detrimental to child cognitive and socio-emotional development. Further evidence suggests that the effects of prenatal lead on developmental outcomes may be conditional upon exposure to social stressors, such as maternal depression and low socioeconomic status. However, no studies have examined associations between these co-occurring stressors during pregnancy and neonatal brain volumes. Leveraging a sample of 101 mother-infant dyads followed beginning in mid-pregnancy, we examined the main effects of prenatal urinary lead levels on neonatal lateralized brain volumes (left and right hippocampus, amygdala, cerebellum, frontal lobes) and total gray matter. We additionally tested for moderations between lead and depressive symptoms and between lead and family income relative to the federal poverty level (FPL) on the same neurodevelopmental outcomes. Analyses of main effects indicated that prenatal lead was significantly (ps < 0.05) associated with reduced right and left amygdala volumes (βs = -0.23- -0.20). The testing and probing of cross-product interaction terms using simple slopes indicated that the negative effect of lead on the left amygdala was conditional upon mothers having low depressive symptoms or high income relative to the FPL. We interpret the results in the context of trajectories of prenatal and postnatal brain development and susceptibility to low levels of prenatal lead in the context of other social stressors.

Associations between early trajectories of amygdala development and later school-age anxiety in two longitudinal samples

Amygdala function is implicated in the pathogenesis of autism spectrum disorder (ASD) and anxiety. We investigated associations between early trajectories of amygdala growth and anxiety and ASD outcomes at school age in two longitudinal studies: high- and low-familial likelihood for ASD, Infant Brain Imaging Study (IBIS, n = 257) and typically developing (TD) community sample, Early Brain Development Study (EBDS, n = 158). Infants underwent MRI scanning at up to 3 timepoints from neonate to 24 months. Anxiety was assessed at 6-12 years. Linear multilevel modeling tested whether amygdala volume growth was associated with anxiety symptoms at school age. In the IBIS sample, children with higher anxiety showed accelerated amygdala growth from 6 to 24 months. ASD diagnosis and ASD familial likelihood were not significant predictors. In the EBDS sample, amygdala growth from birth to 24 months was associated with anxiety. More anxious children had smaller amygdala volume and slower rates of amygdala growth. We explore reasons for the contrasting results between high-familial likelihood for ASD and TD samples, grounding results in the broader literature of variable associations between early amygdala volume and later anxiety. Results have the potential to identify mechanisms linking early amygdala growth to later anxiety in certain groups.

The Association Between Maternal Cortisol and Infant Amygdala Volume Is Moderated by Socioeconomic Status

Background

It has been well established that socioeconomic status is associated with mental and physical health as well as brain development, with emerging data suggesting that these relationships begin in utero. However, less is known about how prenatal socioeconomic environments interact with the gestational environment to affect neonatal brain volume.

Methods

Maternal cortisol output measured at each trimester of pregnancy and neonatal brain structure were assessed in 241 mother-infant dyads. We examined associations between the trajectory of maternal cortisol output across pregnancy and volumes of cortisol receptor-rich regions of the brain, including the amygdala, hippocampus, medial prefrontal cortex, and caudate. Given the known effects of poverty on infant brain structure, socioeconomic disadvantage was included as a moderating variable.

Results

Neonatal amygdala volume was predicted by an interaction between maternal cortisol output across pregnancy and socioeconomic disadvantage (standardized β = -0.31, p < .001), controlling for postmenstrual age at scan, infant sex, and total gray matter volume. Notably, amygdala volumes were positively associated with maternal cortisol for infants with maternal disadvantage scores 1 standard deviation below the mean (i.e., less disadvantage) (simple slope = 123.36, p < .01), while the association was negative in infants with maternal disadvantage 1 standard deviation above the mean (i.e., more disadvantage) (simple slope = -82.70, p = .02). Individuals with disadvantage scores at the mean showed no association, and there were no significant interactions in the other brain regions examined.

Conclusions

These data suggest that fetal development of the amygdala is differentially affected by maternal cortisol production at varying levels of socioeconomic advantage.

Growth of prefrontal and limbic brain regions and anxiety disorders in children born very preterm

BACKGROUND

Children born very preterm (VP) display altered growth in corticolimbic structures compared with full-term peers. Given the association between the cortiocolimbic system and anxiety, this study aimed to compare developmental trajectories of corticolimbic regions in VP children with and without anxiety diagnosis at 13 years.

METHODS

MRI data from 124 VP children were used to calculate whole brain and corticolimbic region volumes at term-equivalent age (TEA), 7 and 13 years. The presence of an anxiety disorder was assessed at 13 years using a structured clinical interview.

RESULTS

VP children who met criteria for an anxiety disorder at 13 years (n = 16) displayed altered trajectories for intracranial volume (ICV, p < 0.0001), total brain volume (TBV, p = 0.029), the right amygdala (p = 0.0009) and left hippocampus (p = 0.029) compared with VP children without anxiety (n = 108), with trends in the right hippocampus (p = 0.062) and left medial orbitofrontal cortex (p = 0.079). Altered trajectories predominantly reflected slower growth in early childhood (0-7 years) for ICV (β = -0.461, p = 0.020), TBV (β = -0.503, p = 0.021), left (β = -0.518, p = 0.020) and right hippocampi (β = -0.469, p = 0.020) and left medial orbitofrontal cortex (β = -0.761, p = 0.020) and did not persist after adjusting for TBV and social risk.

CONCLUSIONS

Region- and time-specific alterations in the development of the corticolimbic system in children born VP may help to explain an increase in anxiety disorders observed in this population.

Amygdala's T1-weighted image radiomics outperforms volume for differentiation of anxiety disorder and its subtype

INTRODUCTION

Anxiety disorder is the most common psychiatric disorder among adolescents, with generalized anxiety disorder (GAD) being a common subtype of anxiety disorder. Current studies have revealed abnormal amygdala function in patients with anxiety compared with healthy people. However, the diagnosis of anxiety disorder and its subtypes still lack specific features of amygdala from T1-weighted structural magnetic resonance (MR) imaging. The purpose of our study was to investigate the feasibility of using radiomics approach to distinguish anxiety disorder and its subtype from healthy controls on T1-weighted images of the amygdala, and provide a basis for the clinical diagnosis of anxiety disorder.

METHODS

T1-weighted MR images of 200 patients with anxiety disorder (including 103 GAD patients) as well as 138 healthy controls were obtained in the Healthy Brain Network (HBN) dataset. We extracted 107 radiomics features for the left and right amygdala, respectively, and then performed feature selection using the 10-fold LASSO regression algorithm. For the selected features, we performed group-wise comparisons, and use different machine learning algorithms, including linear kernel support vector machine (SVM), to achieve the classification between the patients and healthy controls.

RESULTS

For the classification task of anxiety patients vs. healthy controls, 2 and 4 radiomics features were selected from left and right amygdala, respectively, and the area under receiver operating characteristic curve (AUC) of linear kernel SVM in cross-validation experiments was 0.6739±0.0708 for the left amygdala features and 0.6403±0.0519 for the right amygdala features; for classification task for GAD patients vs. healthy controls, 7 and 3 features were selected from left and right amygdala, respectively, and the cross-validation AUCs were 0.6755±0.0615 for the left amygdala features and 0.6966±0.0854 for the right amygdala features. In both classification tasks, the selected amygdala radiomics features had higher discriminatory significance and effect sizes compared with the amygdala volume.

DISCUSSION

Our study suggest that radiomics features of bilateral amygdala potentially could serve as a basis for the clinical diagnosis of anxiety disorder.

Postnatal maternal distress, infant subcortical brain macrostructure and emotional regulation

BACKGROUND

Maternal distress is associated with an increased risk for adverse emotional development in infants, including difficulties with emotion regulation. Prenatal maternal distress has been associated with alterations in infant brain development. However, less is known about these associations with postnatal maternal distress, despite this being an important modifiable risk factor that can promote healthy brain development and emotional outcomes in infants.

METHODS & RESULTS

Infants underwent magnetic resonance imaging (MRI) and mothers completed standardized questionnaires concerning their levels of perceived distress 2-5 months postpartum. Infant emotion regulation was assessed at 8-11 months via maternal report. When examining the associations between maternal distress and infant macrostructure, maternal anxiety was associated with infant right pallidum volumes. Increased display of negative emotions at 8-11 months of age was associated with smaller hippocampal volumes and this association was stronger in girls than boys.

CONCLUSION

Findings suggest that postnatal maternal distress may be associated with early infant brain development and emphasize the importance of maternal mental health, supporting previous work. Furthermore, macrostructural properties of infant subcortical structures may be further investigated as potential biomarkers to identify infants at risk of adverse emotional outcomes.

Extinction Learning Across Development: Neurodevelopmental Changes and Implications for Pediatric Anxiety Disorders

Alterations in extinction learning relate to the development and maintenance of anxiety disorders across the lifespan. While exposure therapy, based on principles of extinction, can be highly effective for treating anxiety, many patients do not show sufficient improvement following treatment. In particular, evidence suggests that exposure therapy does not work sufficiently for up to 40% of children who receive this evidence-based treatment.Importantly, fear learning and extinction, as well as the neural circuitry supporting these processes, undergo dynamic changes across development. An improved understanding of developmental changes in extinction learning and the associated neural circuitry may help to identify targets to improve treatment response in clinically anxious children and adolescents. In this chapter, we provide a brief overview of methods used to study fear learning and extinction in developmental populations. We then review what is currently known about the developmental changes that occur in extinction learning and related neural circuitry. We end this chapter with a discussion of the implications of these neurodevelopmental changes for the characterization and treatment of pediatric anxiety disorders.

Abnormal hubs in global network as potential neuroimaging marker in generalized anxiety disorder at rest

Background

Mounting studies have reported altered neuroimaging features in generalized anxiety disorder (GAD). However, little is known about changes in degree centrality (DC) as an effective diagnostic method for GAD. Therefore, we aimed to explore the abnormality of DCs and whether these features can be used in the diagnosis of GAD.

Methods

Forty-one GAD patients and 45 healthy controls participated in the study. Imaging data were analyzed using DC and receiver operating characteristic (ROC) methods.

Results

Compared with the control group, increased DC values in bilateral cerebellum and left middle temporal gyrus (MTG), and decreased DC values in the left medial frontal orbital gyrus (MFOG), fusiform gyrus (FG), and bilateral posterior cingulate cortex (PCC). The ROC results showed that the DC value of the left MTG could serve as a potential neuroimaging marker with high sensitivity and specificity for distinguishing patients from healthy controls.

Conclusion

Our findings demonstrate that abnormal DCs in the left MTG can be observed in GAD, highlighting the importance of GAD pathophysiology.

Estradiol variability is associated with brain structure in early adolescent females

One-third of adolescents are diagnosed with a psychiatric disorder by age 16, with female adolescents twice as likely to experience an internalizing (i.e., depression or anxiety) disorder as their male peers. Individual differences in pubertal factors may partially underlie this disparity, potentially via the role of pubertal hormones in shaping brain development. While research has examined links between estradiol levels and brain structure, individual variation in estradiol levels has not been considered. Using longitudinal data from 44 female adolescents (baseline age M = 11.7; follow-up age M= 13.3), we examined associations between both average estradiol and estradiol variability, and brain gray matter structure at baseline. We used a hypothesis-driven region of interest (ROI) approach focusing on subcortical and ventromedial prefrontal regions, in addition to an exploratory whole-brain analysis. We also investigated whether brain structure mediated the association between estradiol measures and internalizing (i.e., anxious and depressive) symptoms at follow-up. ROI analyses revealed a significant negative association between estradiol variability and thickness of the right medial orbitofrontal cortex (OFC, β = -0.39, FDR corrected p = .010). There were, however, no significant associations between average estradiol or estradiol variability and internalizing symptoms, nor was there evidence of mediation. Our results indicate that increased variation in estradiol levels across a month is associated with decreased cortical thickness in a brain region implicated in emotion processing, although implications for mental health are unclear. Findings, however, highlight the importance of considering individual variation in estradiol when examining links to brain development.

Associations between anxiety, centromedial amygdala volume, and complex verbal fluency in middle-aged to older adults

Symptoms of anxiety are related to decreases in cognitive performance in middle-aged to older adults (i.e., ages 50 and older; MOA). Verbal fluency (VF), assessed with the Delis-Kaplan Executive Function System (D-KEFS) Category Switching (VF-CS) task, captures elements of executive function such as semantic memory, response initiation and inhibition, and cognitive flexibility. The present study examined the link between anxiety symptoms and VF-CS to better understand how this association affects such executive functions in MOA. We hypothesized that higher subclinical Beck Anxiety Inventory (BAI) scores would be associated with lower VF-CS. To further investigate the underlying neurobiological basis of an expected inverse relationship, total amygdala volume, centromedial amygdala (CMA) volume, and basolateral amygdala (BLA) volume were examined as they related to VF-CS scores on the D-KEFS. Based on extant research on connectivity and functioning between the CMA and BLA, we hypothesized that larger BLA volumes would be associated with lower anxiety scores and exhibit positive relationships with VF-CS. A sample of 63 MOA were recruited from the Providence, Rhode Island area as a part of a parent study on cardiovascular diseases. Participants completed self-report measures about physical and emotional health, a neuropsychological assessment, and a magnetic resonance imaging scan (MRI). Multiple hierarchical regressions were performed to examine relationships between variables of interest. Contrary to hypotheses, no significant relationship emerged between VF-CS and BAI scores, and BLA volume was not associated with either BAI scores or VF-CS. However, a significant positive relationship was observed between CMA volume and VF-CS. The significant relationship found between CMA and VF-CS may reflect the upward slope of the quadratic relationship between arousal and cognitive performance on the Yerkes-Dodson curve. These findings newly implicate CMA volume specifically as a possible neuromarker linking emotional arousal and cognitive performance in MOA.

Anxiety in children and youth with autism spectrum disorder and the association with amygdala subnuclei structure

Autism spectrum disorder (ASD) is clinically characterized by social and communication difficulties as well as repetitive behaviors. Many children with ASD also suffer from anxiety, which has been associated with alterations in amygdala structure. In this work, the association between amygdala subnuclei volumes and anxiety was assessed in a cohort of 234 participants (mean age = 11.0 years, SD = 3.9, 95 children with ASD, 139 children were non-autistic). Children underwent magnetic resonance imaging. Amygdala subnuclei volumes were extracted automatically. Anxiety was assessed using the Screen for Child Anxiety Related Disorders, the Child Behavior Checklist, and the Strength and Difficulties Questionnaire. Children with ASD had higher anxiety scores relative to non-autistic children on all anxiety measures (all, p < 0.05). Anxiety levels were significantly predicted in children with ASD by right basal (right: B = 0.235, p = 0.002) and paralaminar (PL) (B = −0.99, p = 0.009) volumes. Basal nuclei receive multisensory information from cortical and subcortical areas and have extensive projections within the limbic system while the PL nuclei are involved in emotional processing. Alterations in basal and PL nuclei in children with ASD and the association with anxiety may reflect morphological changes related to in the neurocircuitry of anxiety in ASD.

Lay abstract

Autism spectrum disorder (ASD) is clinically characterized by social communication difficulties as well as restricted and repetitive patterns of behavior. In addition, children with ASD are more likely to experience anxiety compared with their peers who do not have ASD. Recent studies suggest that atypical amygdala structure, a brain region involved in emotions, may be related to anxiety in children with ASD. However, the amygdala is a complex structure composed of heterogeneous subnuclei, and few studies to date have focused on how amygdala subnuclei relate to in anxiety in this population. The current sample consisted of 95 children with ASD and 139 non-autistic children, who underwent magnetic resonance imaging (MRI) and assessments for anxiety. The amygdala volumes were automatically segmented. Results indicated that children with ASD had elevated anxiety scores relative to peers without ASD. Larger basal volumes predicted greater anxiety in children with ASD, and this association was not seen in non-autistic children. Findings converge with previous literature suggesting ASD children suffer from higher levels of anxiety than non-autistic children, which may have important implications in treatment and interventions. Our results suggest that volumetric estimation of amygdala’s subregions in MRI may reveal specific anxiety-related associations in children with ASD.

Association of amygdala size with stress perception: Findings of a transversal study across the lifespan

Daily routines are getting increasingly stressful. Interestingly, associations between stress perception and amygdala volume, a brain region implicated in emotional behaviour, have been observed in both younger and older adults. Life stress, on the other hand, has become pervasive and is no longer restricted to a specific age group or life stage. As a result, it is vital to consider stress as a continuum across the lifespan. In this study, we investigated the relationship between perceived stress and amygdala size in 272 healthy participants with a broad age range. Participants were submitted to a structural magnetic resonance imaging (MRI) to extract amygdala volume, and the Perceived Stress Scale (PSS) scores were used as the independent variable in volumetric regressions. We found that perceived stress is positively associated with the right amygdala volume throughout life.

Amygdala subnuclei volumes and anxiety behaviors in children and adolescents with autism spectrum disorder, attention deficit hyperactivity disorder, and obsessive-compulsive disorder

Alterations in the structural maturation of the amygdala subnuclei volumes are associated with anxiety behaviors in adults and children with neurodevelopmental and associated disorders. This study investigated the relationship between amygdala subnuclei volumes and anxiety in 233 children and adolescents (mean age = 11.02 years; standard deviation = 3.17) with autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), and children with obsessive compulsive disorder (OCD), as well as typically developing (TD) children. Parents completed the Child Behavior Checklist (CBCL), and the children underwent structural MRI at 3 T. FreeSurfer software was used to automatically segment the amygdala subnuclei. A general linear model revealed that children and adolescents with ASD, ADHD, and OCD had higher anxiety scores compared to TD children (p < .001). A subsequent interaction analysis revealed that children with ASD (B = 0.09, p < .0001) and children with OCD (B = 0.1, p < .0001) who had high anxiety had larger right central nuclei volumes compared with TD children. Similar results were obtained for the right anterior amygdaloid area. Amygdala subnuclei volumes may be key to identifying children with neurodevelopmental disorders or those with OCD who are at high risk for anxiety. Findings may inform the development of targeted behavioral interventions to address anxiety behaviors and to assess the downstream effects of such interventions.

Reduced cortical volume of the default mode network in adolescents with generalized anxiety disorder

BACKGROUND

Widespread structural alterations have been shown to be implicated in individuals with generalized anxiety disorder (GAD). However, there have been inconsistent findings in cortical volume (CV) differences. Most structural neuroimaging studies looking at GAD used region-based approach with relatively small sample sizes, let alone be specific to adolescents with GAD. We believe this is the first study to look at CV measures using a network-based approach in a larger sample of adolescents with GAD. The goal of the current study was to focus on three different brain networks (i.e., Limbic, Frontoparietal, and Default Mode Network [DMN]) in adolescents with GAD.

METHOD

The study involved 81 adolescents with GAD and 112 typically developing (TD) comparison individuals matched on age (15.98 and 15.63 respective means), sex (42F/39M and 45F/67M), and IQ (101.90 and 103.94 respective means). Participants underwent structural MRI. Freesurfer was used to estimate CV (both network-specific and region-specific within networks) and region-specific sub-cortical volume measures. Multivariate analysis of covariance (MANCOVA; with sex, age, IQ, and intracranial volume [ICV] as potential covariates) was used to estimate group differences.

RESULTS

We found significantly lower CV for the DMN in adolescents with GAD, compared with TD individuals. Adolescents with GAD also showed significantly lower hemispheric mean CV of the default-mode regions (particularly the prefrontal and temporal regions) and the hippocampus, compared with TD individuals.

CONCLUSION

The current findings suggest structural alterations in adolescents with GAD. These structural alterations will need to be addressed when implementing and developing treatments for patients with GAD.

Association of Amygdala Development With Different Forms of Anxiety in Autism Spectrum Disorder

BACKGROUND

The amygdala is widely implicated in both anxiety and autism spectrum disorder. However, no studies have investigated the relationship between co-occurring anxiety and longitudinal amygdala development in autism. Here, the authors characterize amygdala development across childhood in autistic children with and without traditional DSM forms of anxiety and anxieties distinctly related to autism.

METHODS

Longitudinal magnetic resonance imaging scans were acquired at up to four time points for 71 autistic and 55 typically developing (TD) children (∼2.5-12 years, 411 time points). Traditional DSM anxiety and anxieties distinctly related to autism were assessed at study time 4 (∼8-12 years) using a diagnostic interview tailored to autism: the Anxiety Disorders Interview Schedule-IV with the Autism Spectrum Addendum. Mixed-effects models were used to test group differences at study time 1 (3.18 years) and time 4 (11.36 years) and developmental differences (age-by-group interactions) in right and left amygdala volume between autistic children with and without DSM or autism-distinct anxieties and TD children.

RESULTS

Autistic children with DSM anxiety had significantly larger right amygdala volumes than TD children at both study time 1 (5.10% increase) and time 4 (6.11% increase). Autistic children with autism-distinct anxieties had significantly slower right amygdala growth than TD, autism-no anxiety, and autism-DSM anxiety groups and smaller right amygdala volumes at time 4 than the autism-no anxiety (-8.13% decrease) and autism-DSM anxiety (-12.05% decrease) groups.

CONCLUSIONS

Disparate amygdala volumes and developmental trajectories between DSM and autism-distinct forms of anxiety suggest different biological underpinnings for these common, co-occurring conditions in autism.

Amygdala-driven apnea and the chemoreceptive origin of anxiety

Although the amygdala plays an important part in the pathogenesis of anxiety and generation of exteroceptive fear, recent discoveries have challenged the directionality of this brain-behavior relationship with respect to interoceptive fear. Here we highlight several paradoxical findings including: (1) amygdala lesion patients who experience excessive fear and panic following inhalation of carbon dioxide (CO₂), (2) clinically anxious patients who have significantly smaller (rather than larger) amygdalae and a pronounced hypersensitivity toward CO₂, and (3) epilepsy patients who exhibit apnea immediately following stimulation of their amygdala yet have no awareness that their breathing has stopped. The above findings elucidate an entirely novel role for the amygdala in the induction of apnea and inhibition of CO₂-induced fear. Such a role is plausible given the strong inhibitory connections linking the central nucleus of the amygdala with respiratory and chemoreceptive centers in the brainstem. Based on this anatomical arrangement, we propose a model of Apnea-induced Anxiety (AiA) which predicts that recurring episodes of apnea are being unconsciously elicited by amygdala activation, resulting in transient spikes in CO₂ that provoke fear and anxiety, and lead to characteristic patterns of escape and avoidance behavior in patients spanning the spectrum of anxiety. If this new conception of AiA proves to be true, and activation of the amygdala can repeatedly trigger states of apnea outside of one's awareness, then it remains possible that the chronicity of anxiety disorders is being interoceptively driven by a chemoreceptive system struggling to maintain homeostasis in the midst of these breathless states.

Consequences of Inadequate Caregiving for Children's Attachment, Neurobiological Development, and Adaptive Functioning

Given that human infants are almost fully reliant on caregivers for survival, the presence of parents who provide sensitive, responsive care support infants and young children in developing the foundation for optimal biological functioning. Conversely, when parents are unavailable or insensitive, there are consequences for infants' and children's attachment and neurobiological development. In this paper, we describe effects of inadequate parenting on children's neurobiological and behavioral development, with a focus on developing capacities for executive functioning, emotion regulation, and other important cognitive-affective processes. Most prior research has examined correlational associations among these constructs. Given that interventions tested through randomized clinical trials allow for causal inferences, we review longitudinal intervention effects on children's biobehavioral and cognitive-affective outcomes. In particular, we provide an overview of the Bucharest Early Intervention Project, a study in which children were randomized to continue in orphanage care (typically the most extreme condition of privation) or were placed into the homes of trained, supported foster parents. We also discuss findings regarding Attachment and Biobehavioral Catch-up, an intervention enhancing sensitivity among high-risk parents. We conclude by suggesting future directions for research in this area.

Alterations between high and low-avoidance lines of Hatano rats in learning behaviors, ultrasonic vocalizations, and histological characteristics in hippocampus and amygdala

Growing evidence supports interactions between anxiety and cognitive function. The primary object of this study was to elucidate whether high-avoidance (HAA) and low-avoidance (LAA) strains of Hatano rats are suitable for the analysis of interactions between the formation of long-term memory and emotional reactivity. The learning/memory ability of Hatano rats and their Sprague-Dawley (SD) ancestors was evaluated using contextual fear conditioning, Y-maze, and Barnes maze tests from 8 weeks of age. Ultrasonic vocalizations were recorded and analyzed during contextual fear conditioning. In a separate experiment, rat brains were sampled 90 min after the first context test and subjected to Nissl staining and c-fos immunostaining. The duration of freezing and number of 22 kHz ultrasonic vocalizations were decreased in LAA compared with HAA and SD rats during the first and second context tests of contextual fear conditioning. The HAA rats did not show preferences for quadrants during the Barnes maze probe test, whereas the SD and LAA rats spent significantly more time in the quadrant where the goals had been placed. There was no difference among the strains in short-term spatial memory as shown by the Y-maze test. Decreases were found in the number of c-fos⁺ cells as well as the volume of some hippocampal regions in the HAA rats compared to SD and LAA rats. By contrast, the volume of the basolateral amygdala was bigger in the HAA than the other strains. On the basis of the 22 kHz ultrasonic calls and literature regarding Syracuse rats, the possibility that emotional reactivity influences contextual memory in Hatano strains was discussed. This emotional difference may be derived from structural and/or functional divergence in the hippocampus and amygdala between the strains. The cause of strain-related differences in long-term spatial learning was difficult to elucidate because there are several possible explanations, including differences in memory and/or the interference of hyperactivity during the Barnes maze test.

Charting the human amygdala development across childhood and adolescence: Manual and automatic segmentation

The developmental pattern of the amygdala throughout childhood and adolescence has been inconsistently reported in previous neuroimaging studies. Given the relatively small size of the amygdala on full brain MRI scans, discrepancies may be partly due to methodological differences in amygdalar segmentation. To investigate the impact of volume extraction methods on amygdala volume, we compared FreeSurfer, FSL and volBrain segmentation measurements with those obtained by manual tracing. The manual tracing method, which we used as the 'gold standard', exhibited almost perfect intra- and inter-rater reliability. We observed systematic differences in amygdala volumes between automatic (FreeSurfer and volBrain) and manual methods. Specifically, compared with the manual tracing, FreeSurfer estimated larger amygdalae, and volBrain produced smaller amygdalae while FSL demonstrated a mixed pattern. The tracing bias was not uniform, but higher for smaller amygdalae. We further modeled amygdalar growth curves using accelerated longitudinal cohort data from the Chinese Color Nest Project (http://deepneuro.bnu.edu.cn/?p=163). Trajectory modeling and statistical assessments of the manually traced amygdalae revealed linearly increasing and parallel developmental patterns for both girls and boys, although the amygdalae of boys were larger than those of girls. Compared to these trajectories, the shapes of developmental curves were similar when using the volBrain derived volumes. FreeSurfer derived trajectories had more nonlinearities and appeared flatter. FSL derived trajectories demonstrated an inverted U shape and were significantly different from those derived from manual tracing method. The use of amygdala volumes adjusted for total gray-matter volumes, but not intracranial volumes, resolved the shape discrepancies and led to reproducible growth curves between manual tracing and the automatic methods (except FSL). Our findings revealed steady growth of the human amygdala, mirroring its functional development across the school age. Methodological improvements are warranted for current automatic tools to achieve more accurate amygdala structure at school age, calling for next generation tools.

Within amygdala: Basolateral parts are selectively impaired in premature-born adults

While it is known that whole amygdala volume is lastingly reduced after premature birth, it is unknown whether different amygdala nuclei are distinctively affected by prematurity. This question is motivated by two points: First, the observation that developmental trajectories of superficial, centromedial and basolateral amygdala nuclei are different. And second, the expectation that these different developmental pathways are distinctively affected by prematurity. Furthermore, we stated the question whether alterations in amygdala nuclei are associated with increased adults' anxiety traits after premature birth. We investigated 101 very premature-born adults (<32 weeks of gestation and/or birth weight below 1500 g) and 108 full-term controls of a prospectively and longitudinally collected cohort at 26 years of age using automated amygdala nuclei segmentation based on structural MRI. We found selectively reduced volumes of bilateral accessory basal nuclei (pertaining to the basolateral amygdala of claustral developmental trajectory) adjusted for whole amygdala volume. Volumes of bilateral accessory basal nuclei were positively associated with gestational age and negatively associated with duration of ventilation. Furthermore, structural covariance within the basolateral amygdala was increased in premature-born adults. We did not find an association between reduced volumes of basolateral amygdala and increased social anxiety in the prematurity group. These results demonstrate specifically altered basolateral amygdala structure in premature-born adults. Data suggest that prematurity has distinct effects on amygdala nuclei.

Amygdala subnuclei development in adolescents with autism spectrum disorder: Association with social communication and repetitive behaviors

INTRODUCTION

The amygdala subnuclei regulate emotional processing and are widely implicated in social cognitive impairments often seen in children with autism spectrum disorder (ASD). Dysregulated amygdala development has been reported in young children with ASD; less is known about amygdala maturation in later adolescence, a sensitive window for social skill development.

METHODS

The macrostructural development of the amygdala subnuclei was assessed at two time points in a longitudinal magnetic resonance imaging (MRI) study of adolescents with ASD (n = 23) and typically-developing adolescents (n = 15) . In adolescents with ASD, amygdala subnuclei growth was assessed in relation to ASD symptomatology based on standardized diagnostic assessments. Participants were scanned with MRI at median age of 12 years and returned for a second scan at a median age of 15 years. The volumes of nine amygdala subnuclei were extracted using an automatic segmentation algorithm.

RESULTS

When examining the longitudinal data acquired across two time points, adolescents with ASD had larger basolateral amygdala (BLA) nuclei volumes compared to typically developing adolescents (B = 46.8, p = 0.04). When examining ASD symptomatology in relation to the growth of the amygdala subnuclei, reciprocal social interaction scores on the ADI-R were positively associated with increased growth of the BLA nuclei (B = 8.3, p < 0.001). Growth in the medial nucleus negatively predicted the communication (B = -46.9, p = 0.02) and social (B = -47.7, p < 0.001) domains on the ADOS-G. Growth in the right cortical nucleus (B = 26.14, p = 0.02) positively predicted ADOS-G social scores. Central nucleus maturation (B = 29.9, p = 0.02) was associated with the repetitive behaviors domain on the ADOS-G.

CONCLUSIONS

Larger BLA volumes in adolescents with ASD may reflect underlying alterations in cellular density previously reported in post-mortem studies. Furthermore, findings demonstrate an association between regional growth in amygdala subnuclei volumes and ASD symptomatology. Improved understanding of the developmental trajectories of the amygdala subnuclei may aid in identifying key windows for interventions, particularly for social communication, in adolescents with ASD.

Leveraging big data to map neurodevelopmental trajectories in pediatric anxiety

Anxiety disorders are the most prevalent psychiatric condition among youth, with symptoms commonly emerging prior to or during adolescence. Delineating neurodevelopmental trajectories associated with anxiety disorders is important for understanding the pathophysiology of pediatric anxiety and for early risk identification. While a growing literature has yielded valuable insights into the nature of brain structure and function in pediatric anxiety, progress has been limited by inconsistent findings and challenges common to neuroimaging research. In this review, we first discuss these challenges and the promise of ‘big data’ to map neurodevelopmental trajectories in pediatric anxiety. Next, we review evidence of age-related differences in neural structure and function among anxious youth, with a focus on anxiety-relevant processes such as threat and safety learning. We then highlight large-scale cross-sectional and longitudinal studies that assess anxiety and are well positioned to inform our understanding of neurodevelopment in pediatric anxiety. Finally, we detail relevant challenges of ‘big data’ and propose future directions through which large publicly available datasets can advance knowledge of deviations from normative brain development in anxiety. Leveraging ‘big data’ will be essential for continued progress in understanding the neurobiology of pediatric anxiety, with implications for identifying markers of risk and novel treatment targets.

Amygdala size varies with stress perception

Stress is inevitably linked to life. It has many and complex facets. Notably, perception of stressful stimuli is an important factor when mounting stress responses and measuring its impact. Indeed, moved by the increasing number of stress-triggered pathologies, several groups drew on advanced neuroimaging techniques to explore stress effects on the brain. From that, several regions and circuits have been linked to stress, and a comprehensive integration of the distinct findings applied to common individuals is being pursued, but with conflicting results. Herein, we performed a volumetric regression analysis using participants’ perceived stress as a variable of interest. Data shows that increased levels of perceived stress positively associate with the right amygdala and anterior hippocampal volumes.

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Discrepant stress effects on morphology are reported in the literature.

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Stress definition and analysis software are the main causes of conflicting findings.

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Psychological measures and multi-technique analysis are highly recommended.

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We found that perceived stress positively associates with right amygdala volumes.

Larger bilateral amygdalar volumes are associated with affective loss experiences

Affective loss (AL) (i.e., bereavement, relationship breakup) is a stressful life event leading to a heightened risk of developing a psychiatric disorder, for example, depression and anxiety disorder. These disorders have been associated with altered subcortical brain volumes. Little is known though, how AL in healthy subjects is linked to subcortical volumes. In a study with 196 healthy young adults, we probed the association between AL across the individual entire life span, assessed via the List of Threatening Experiences Questionnaire, and magnetic resonance imaging brain gray matter volumes (a priori selected: bilateral amygdalae, hippocampi, thalami; exploratory analyses: nuclei accumbens, caudate, putamina), segmented by use of volBrain. AL was defined as death of a first-degree relative/spouse, close relative/friend, and breakup of a marriage or steady relationship. AL was associated with larger bilateral amygdalar volumes and, after taking into account the total number of ALs, with smaller right hippocampal volumes, both irrespective of sex. Exploratory analyses of striatal volumes yielded an association of AL with larger right nucleus accumbens volumes in men, and increased caudate volumes after the loss of a first-degree relative irrespective of sex. Our data suggest that AL engenders alterations in limbic structures that likely involve processes of chronic stress and amygdala- and hippocampus-dependent fear conditioning, and resemble those observed in general anxiety disorder, childhood maltreatment, and major depressive disorder. Our exploratory findings of striatal volume alterations hint at a modulation of reward processing by AL.

Prefrontal cortex and amygdala anatomy in youth with persistent levels of harsh parenting practices and subclinical anxiety symptoms over time during childhood

Childhood adversity and anxiety have been associated with increased risk for internalizing disorders later in life and with a range of brain structural abnormalities. However, few studies have examined the link between harsh parenting practices and brain anatomy, outside of severe maltreatment or psychopathology. Moreover, to our knowledge, there has been no research on parenting and subclinical anxiety symptoms which remain persistent over time during childhood (i.e., between 2.5 and 9 years old). Here, we examined data in 94 youth, divided into four cells based on their levels of coercive parenting (high / low) and of anxiety (high / low) between 2.5 and 9 years old. Anatomical images were analyzed using voxel-based morphometry (VBM) and FreeSurfer. Smaller gray matter volumes in the prefrontal cortex regions and in the amygdala were observed in youth with high versus low levels of harsh parenting over time. In addition, we observed significant interaction effects between parenting practices and subclinical anxiety symptoms in rostral anterior cingulate cortical thickness and in amygdala volume. These youth should be followed further in time to identify which youth will or will not go on to develop an anxiety disorder, and to understand factors associated with the development of sustained anxiety psychopathology.

Decreased amygdala volume in adults after premature birth

Premature-born infants have impaired amygdala structure, presumably due to increased stress levels of premature birth mediated by the amygdala. However, accounting for lifelong plasticity of amygdala, it is unclear whether such structural changes persist into adulthood. To address this problem, we stated the following questions: first, are whole amygdala volumes reduced in premature-born adults? And second, as adult anxiety traits are often increased after prematurity and linked with amygdala structure, are alterations in amygdala associated with adults' anxiety traits after premature birth? We addressed these questions by automated amygdala segmentation of MRI volumes in 101 very premature-born adults (< 32 weeks of gestation and/or birth weight below 1500 g) and 108 full-term controls at 26 years of age of a prospectively and longitudinally collected cohort. We found significantly lower whole amygdala volumes in premature-born adults. While premature-born adults had significantly higher T score for avoidant personality reflecting increased social anxiety trait, this trait was not correlated with amygdala volume alterations. Results demonstrate reduced amygdala volumes in premature born adults. Data suggest lasting effects of prematurity on amygdala structure.

Critical aspects of neurodevelopment

Organisms have the unique ability to adapt to their environment by making use of external inputs. In the process, the brain is shaped by experiences that go hand-in-hand with optimisation of neural circuits. As such, there exists a time window for the development of different brain regions, each unique for a particular sensory modality, wherein the propensity of forming strong, irreversible connections are high, referred to as a critical period of development. Over the years, this domain of neurodevelopmental research has garnered considerable attention from many scientists, primarily because of the intensive activity-dependent nature of development. This review discusses the cellular, molecular, and neurophysiological bases of critical periods of different sensory modalities, and the disorders associated in cases the regulators of development are dysfunctional. Eventually, the neurobiological bases of the behavioural abnormalities related to developmental pathologies are discussed. A more in-depth insight into the development of the brain during the critical period of plasticity will eventually aid in developing potential therapeutics for several neurodevelopmental disorders that are categorised under critical period disorders.

Research Review: Pediatric anxiety disorders - what have we learnt in the last 10 years?

BACKGROUND

Anxiety disorders first emerge during the critical developmental periods of childhood and adolescence. This review synthesizes recent findings on the prevalence, risk factors, and course of the anxiety disorders; and their neurobiology and treatment.

METHODS

For this review, searches were conducted using PubMed, PsycINFO, and clinicaltrials.gov. Findings related to the epidemiology, neurobiology, risk factors, and treatment of pediatric anxiety disorders were then summarized.

FINDINGS

Anxiety disorders are high prevalence, and early-onset conditions associated with multiple risk factors including early inhibited temperament, environment stress, and structural and functional abnormalities in the prefrontal-amygdala circuitry as well as the default mode and salience networks. The anxiety disorders are effectively treated with cognitive behavioral therapy (CBT), selective serotonin reuptake inhibitors (SSRIs), and serotonin-norepinephrine reuptake inhibitors (SNRIs).

CONCLUSIONS

Anxiety disorders are high prevalence, early-onset conditions associated with a distinct neurobiological fingerprint, and are consistently responsive to treatment. Questions remain regarding who is at risk of developing anxiety disorders as well as the way in which neurobiology predicts treatment response.

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

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

Fear Potentiated Startle in Children With Autism Spectrum Disorder: Association With Anxiety Symptoms and Amygdala Volume

Atypical responses to fearful stimuli and the presence of various forms of anxiety are commonly seen in children with autism spectrum disorder (ASD). The fear potentiated startle paradigm (FPS), which has been studied both in relation to anxiety and as a probe for amygdala function, was carried out in 97 children aged 9-14 years including 48 (12 female) with ASD and 49 (14 female) with typical development (TD). In addition, exploratory analyses were conducted examining the association between FPS and amygdala volume as assessed with magnetic resonance imaging in a subset of the children with ASD with or without an anxiety disorder with available MRI data. While the startle latency was increased in the children with ASD, there was no group difference in FPS. FPS was not significantly associated with traditional Diagnostic and Statistical Manual (DSM) or "autism distinct" forms of anxiety. Within the autism group, FPS was negatively correlated with amygdala volume. Multiple regression analyses revealed that the association between FPS and anxiety severity was significantly moderated by the size of the amygdala, such that the association between FPS and anxiety was significantly more positive in children with larger amygdalas than smaller amygdalas. These findings highlight the heterogeneity of emotional reactivity associated with ASD and the difficulties in establishing biologically meaningful probes of altered brain function. LAY SUMMARY: Many children with autism spectrum disorder (ASD) have additional problems such as anxiety that can greatly impact their lives. How these co-occurring symptoms develop is not well understood. We studied the amygdala, a region of the brain critical for processing fear and a laboratory method called fear potentiated startle for measuring fear conditioning, in children with ASD (with and without an anxiety disorder) and typically developing children. Results showed that the connection between fear conditioning and anxiety is dependent on the size of the amygdala in children with ASD.

A conceptual model of risk and protective factors associated with internalizing symptoms in autism spectrum disorder: A scoping review, synthesis, and call for more research

This paper reviews and synthesizes key areas of research related to the etiology, development, and maintenance of internalizing symptoms in children, adolescents, and adults with autism spectrum disorder (ASD). In developing an integrated conceptual model, we draw from current conceptual models of internalizing symptoms in ASD and extend the model to include factors related to internalizing within other populations (e.g., children that have experienced early life stress, children with other neurodevelopmental conditions, typically developing children) that have not been systematically examined in ASD. Our review highlights the need for more research to understand the developmental course of internalizing symptoms, potential moderators, and the interplay between early risk and protective factors. Longitudinal studies incorporating multiple methods and both environmental and biological factors will be important in order to elucidate these mechanisms.

Neuroinflammation-Associated Alterations of the Brain as Potential Neural Biomarkers in Anxiety Disorders

Stress-induced changes in the immune system, which lead to neuroinflammation and consequent brain alterations, have been suggested as possible neurobiological substrates of anxiety disorders, with previous literature predominantly focusing on panic disorder, agoraphobia, and generalized anxiety disorder, among the anxiety disorders. Anxiety disorders have frequently been associated with chronic stress, with chronically stressful situations being reported to precipitate the onset of anxiety disorders. Also, chronic stress has been reported to lead to hypothalamic–pituitary–adrenal axis and autonomic nervous system disruption, which may in turn induce systemic proinflammatory conditions. Preliminary evidence suggests anxiety disorders are also associated with increased inflammation. Systemic inflammation can access the brain, and enhance pro-inflammatory cytokine levels that have been shown to precipitate direct and indirect neurotoxic effects. Prefrontal and limbic structures are widely reported to be influenced by neuroinflammatory conditions. In concordance with these findings, various imaging studies on panic disorder, agoraphobia, and generalized anxiety disorder have reported alterations in structure, function, and connectivity of prefrontal and limbic structures. Further research is needed on the use of inflammatory markers and brain imaging in the early diagnosis of anxiety disorders, along with the possible efficacy of anti-inflammatory interventions on the prevention and treatment of anxiety disorders.

Parsing differences in amygdala volume among individuals with and without social and generalized anxiety disorders across the lifespan

Structural differences in the amygdala (AMG) are implicated in anxiety and observed among individuals with generalized (GAD) and social anxiety (SAD) disorders. Findings have been mixed, perhaps because studies rarely examine differences between GAD and SAD, test comorbidity, or examine age-related differences. We tested AMG volume differences among a sample of adults and youth with/without SAD and GAD. Participants (N = 242; ages 7-60 years) completed an MRI scan, diagnostic interviews, and anxiety symptom measures. Groups were formed from diagnostic interviews: 1) Typically developing (TD; n = 91); 2) GAD (n = 53); 3) SAD (n = 35); and 4) comorbid SAD/GAD (n = 63). We used analysis of covariance with a bonferroni correction to examine group differences in AMG volume. The SAD and comorbid SAD/GAD groups exhibited increased bilateral AMG volume compared to the TD group. GAD and TD groups did not differ from each other in AMG size. The SAD, but not the comorbid SAD/GAD group, displayed greater right AMG size relative to the GAD group. SAD and comorbid SAD/GAD groups did not differ from the GAD group in left AMG volume. SAD and SAD/GAD groups did not exhibit different bilateral AMG size. Linear regression analyses demonstrated that greater social anxiety but not generalized anxiety symptom severity was associated with enlarged AMG volume. Age was not associated with AMG volume and nor did age moderate any group or symptom effects. Future longitudinal studies should examine whether larger AMG volume is a unique biomarker for SAD across the lifespan.

Progressive brain structural alterations assessed via causal analysis in patients with generalized anxiety disorder

Accumulating neuroimaging studies implicate widespread brain structural alterations in patients with generalized anxiety disorder (GAD), but little is known regarding the temporal information of these changes and their causal relationships. In this study, a morphometric analysis was performed on T1-weighted structural images, and the progressive changes in the gray matter volume (GMV) in GAD were simulated by dividing the patients into different groups from low illness duration to high illness duration. The duration was defined as the interval between the onset of GAD and the time for magnetic resonance imaging collection. Then, a causal structural covariance network analysis was conducted to describe the causal relationships of the brain structural alterations in GAD. With increased illness duration, the GMV reduction in GAD originated from the subgenual anterior cingulate cortex (sgACC) and propagated to the bilateral ventromedial prefrontal cortex, right dorsomedial prefrontal cortex, left inferior temporal gyrus, and right insula. Intriguingly, the sgACC and the right insula had positive causal effects on each other. Moreover, both sgACC and right insula exhibited positive causal effects on the parietal cortex and negative effects on the posterior cingulate cortex, dorsolateral prefrontal cortex, visual cortex, and temporal lobe. The opposite causal effects were noted on the somatosensory and the ventrolateral prefrontal cortices. In conclusion, patients with GAD show gradual GMV reduction with increasing ilness duration. Furthermore, the causal effects of the sgACC and the right insula GMV reduction with shifts of duration may provide an important new avenue for understanding the pathological anomalies in GAD.

Material hardship, prefrontal cortex-amygdala structure, and internalizing symptoms in children

Material hardship, or difficulty affording basic resources such as food, housing, utilities, and health care, increases children's risk for internalizing problems. The uncinate fasciculus (UNC) and two of the gray matter regions it connects-the orbitofrontal cortex (OFC) and amygdala-may play important roles in the neural mechanisms underlying these associations. We investigated associations among material hardship, UNC microstructure, OFC and amygdala structure, and internalizing symptoms in children. Participants were 5-9-year-old children (N = 94, 61% female) from socioeconomically diverse families. Parents completed questionnaires assessing material hardship and children's internalizing symptoms. High-resolution, T1-weighted magnetic resonance imaging (n = 51), and diffusion tensor imaging (n = 58) data were acquired. UNC fractional anisotropy (FA), medial OFC surface area, and amygdala gray matter volume were extracted. Greater material hardship was significantly associated with lower UNC FA, smaller amygdala volume, and higher internalizing symptoms in children, after controlling for age, sex, and family income-to-needs ratio. Lower UNC FA significantly mediated the association between material hardship and internalizing symptoms in girls but not boys. These findings are consistent with the notion that material hardship may lead to altered white matter microstructure and gray matter structure in neural networks critical to emotion processing and regulation.

Socioeconomic disadvantage, brain morphometry, and attentional bias to threat in middle childhood

Socioeconomic disadvantage is associated with higher rates of psychopathology as well as hippocampus, amygdala and prefrontal cortex structure. However, little is known about how variations in brain morphometry are associated with socio-emotional risks for mood disorders in children growing up in families experiencing low income. In the current study, using structural magnetic resonance imaging, we examined the relationship between socioeconomic disadvantage and gray matter volume in the hippocampus, amygdala, and ventrolateral prefrontal cortex in a sample of children (n = 34) in middle childhood. Using an affective dot probe paradigm, we examined the association between gray matter volume in these regions and attentional bias to threat, a risk marker for mood disorders including anxiety disorders. We found that lower income-to-needs ratio was associated with lower bilateral hippocampal and right amygdala volume, but not prefrontal cortex volumes. Moreover, lower attentional bias to threat was associated with greater left hippocampal volume. We provide evidence of a relationship between income-related variations in brain structure and attentional bias to threat, a risk for mood disorders. Therefore, these findings support an environment-morphometry-behavior relationship that contributes to the understanding of income-related mental health disparities in childhood.

Self-Efficacy As a Target for Neuroscience Research on Moderators of Treatment Outcomes in Pediatric Anxiety

Objective: Despite the advances in the field of neuroscience, many questions remain regarding the mechanisms of anxiety, as well as moderators of treatment outcome. Long-term adverse outcomes for anxious youth may relate to pathophysiologically based information processing patterns and self-referential beliefs, such as self-efficacy. In fact, there are no studies highlighting the relationship between self-efficacy and neurocircuitry in youth. The purpose of this study was to explore the relationships between self-efficacy, brain morphometry, and youth anxiety. Methods: Parent, child, and clinician ratings of anxiety symptoms and child-reported self-efficacy were analyzed in a sample of 8- to 17-year-old youth (n = 51). Measures were collected from all youth at baseline and during and after treatment for the patients. Anxious patients (n = 26) received 12 sessions of cognitive behavioral therapy (CBT). Moreover, imaging data obtained from all participants before treatment were utilized in analyses. Results: Patients reported lower self-efficacy than healthy volunteers. Across the entire sample, anxiety was negatively related to total, social, and emotional efficacy. Both social and emotional efficacy predicted anxiety posttreatment. In addition, social efficacy predicted social anxiety symptoms posttreatment and social efficacy increased across treatment. There were no significant relations between self-efficacy and neurocircuitry. Conclusions: Self-efficacy is an important treatment target for anxious youth. Although self-efficacy was not related to brain morphometry, self-efficacy beliefs may constitute an important mechanism through which CBT and psychopharmacological interventions decrease fear and anxiety symptoms in youth.

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.

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.

Environmental Tobacco Smoke During the Early Postnatal Period of Mice Interferes With Brain 18 F-FDG Uptake From Infancy to Early Adulthood - A Longitudinal Study

Exposure to environmental tobacco smoke (ETS) is associated with high morbidity and mortality, mainly in childhood. Our aim was to evaluate the effects of postnatal ETS exposure in the brain 2-deoxy-2-[¹⁸F]-fluoro-D-glucose (¹⁸F-FDG) uptake of mice by positron emission tomography (PET) neuroimaging in a longitudinal study. C57BL/6J mice were exposed to ETS that was generated from 3R4F cigarettes from postnatal day 3 (P3) to P14. PET analyses were performed in male and female mice during infancy (P15), adolescence (P35), and adulthood (P65). We observed that ETS exposure decreased ¹⁸F-FDG uptake in the whole brain, both left and right hemispheres, and frontal cortex in both male and female infant mice, while female infant mice exposed to ETS showed decreased ¹⁸F-FDG uptake in the cerebellum. In addition, all mice showed reduced ¹⁸F-FDG uptake in infancy, compared to adulthood in all analyzed VOIs. In adulthood, ETS exposure during the early postnatal period decreased brain ¹⁸F-FDG uptake in adult male mice in the cortex, striatum, hippocampus, cingulate cortex, and thalamus when compared to control group. ETS induced an increase in ¹⁸F-FDG uptake in adult female mice when compared to control group in the brainstem and cingulate cortex. Moreover, male ETS-exposed animals showed decreased ¹⁸F-FDG uptake when compared to female ETS-exposed in the whole brain, brainstem, cortex, left amygdala, striatum, hippocampus, cingulate cortex, basal forebrain and septum, thalamus, hypothalamus, and midbrain. The present study shows that several brain regions are vulnerable to ETS exposure during the early postnatal period and these effects on ¹⁸F-FDG uptake are observed even a long time after the last exposure. This study corroborates our previous findings, strengthening the idea that exposure to tobacco smoke in a critical period interferes with brain development of mice from late infancy to early adulthood.

Linking personality and brain anatomy: a structural MRI approach to Reinforcement Sensitivity Theory

Reinforcement Sensitivity Theory (RST) proposes a widely used taxonomy of human personality linked to individual differences at both behavioral and neuropsychological levels that describe a predisposition to psychopathology. However, the body of RST research was based on animal findings, and little is known about their anatomical correspondence in humans. Here we set out to investigate MRI structural correlates (i.e. voxel-based morphometry) of the main personality dimensions proposed by the RST in a group of 400 healthy young adults who completed the Sensitivity to Punishment and Sensitivity to Reward Questionnaire (SPSRQ). Sensitivity to punishment scores correlated positively with the gray matter volume in the amygdala, whereas sensitivity to reward scores correlated negatively with the volume in the left lateral and medial prefrontal cortex. Moreover, a negative relationship was found between the striatal volume and the reward sensitivity trait, but only for male participants. The present results support the neuropsychological basis of the RST by linking punishment and reward sensitivity to anatomical differences in limbic and frontostriatal regions, respectively. These results are interpreted based on previous literature related to externalizing and internalizing disorders, and they highlight the possible role of SPSRQ as a measure of proneness to these disorders.

A computationally inspired in-vivo approach identifies a link between amygdalar transcriptional heterogeneity, socialization and anxiety

Pharmaceutical breakthroughs for anxiety have been lackluster in the last half-century. Converging behavior and limbic molecular heterogeneity has the potential to revolutionize biomarker-driven interventions. However, current in vivo models too often deploy artificial systems including directed evolution, mutations and fear induction, which poorly mirror clinical manifestations. Here, we explore transcriptional heterogeneity of the amygdala in isogenic mice using an unbiased multi-dimensional computational approach that segregates intra-cohort reactions to moderate situational adversity and intersects it with high content molecular profiling. We show that while the computational approach stratifies known features of clinical anxiety including nitric oxide, opioid and corticotropin signaling, previously unrecognized druggable biomarkers emerge, such as calpain11 and scand1. Through ingenuity pathway analyses, we further describe a role for neurosteroid estradiol signaling, heat shock proteins, ubiquitin ligases and lipid metabolism. In addition, we report a remarkable behavioral pattern that maps to molecular features of anxiety in mice through counterphobic social attitudes, which manifest as increased, yet spatially distant socialization. These findings provide an unbiased approach for interrogating anxiolytics, and hint toward biomarkers underpinning behavioral and social patterns that merit further exploration.

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.

Morphometric Biomarkers of Adolescents With Familial Risk for Alcohol Use Disorder

BACKGROUND

While many adolescents exhibit risky behavior, teenagers with a family history (FH+) of an alcohol use disorder (AUD) are at a heightened risk for earlier initiation of alcohol use, a more rapid escalation in frequency and quantity of alcohol consumption and developing a subsequent AUD in comparison with youth without such family history (FH-). Neuroanatomically, developmentally normative risk-taking behavior parallels an imbalance between more protracted development of the prefrontal cortex (PFC) and earlier development of limbic regions. Magnetic resonance imaging (MRI)-derived volumetric properties were obtained for these structures in FH+ and FH- adolescents.

METHODS

Forty-two substance-naïve adolescents (13- to 14-year-olds), stratified into FH+ (N = 19, 13 girls) and FH- (N = 23, 11 girls) age/handedness-matched groups, completed MRI scanning at 3.0T, as well as cognitive and clinical testing. T1 images were processed using FreeSurfer to measure PFC and hippocampi/amygdalae subfields/nuclei volumes.

RESULTS

FH+ status was associated with larger hippocampal/amygdala volumes (p < 0.05), relative to FH- adolescents, with right amygdala results appearing to be driven by FH+ boys. Volumetric differences also were positively associated with family history density (p < 0.05) of having an AUD. Larger subfields/nuclei volumes were associated with higher anxiety levels and worse auditory verbal learning performance (p < 0.05).

CONCLUSIONS

FH+ risk for AUD is detectable via neuromorphometric characteristics, which precede alcohol use onset and the potential onset of a later AUD, that are associated with emotional and cognitive measures. It is plausible that the development of limbic regions might be altered in FH+ youth, even prior to the onset of alcohol use, which could increase later risk. Thus, targeted preventative measures are warranted that serve to delay the onset of alcohol use in youth, particularly in those who are FH+ for an AUD.