Mega-analysis methods in ENIGMA: The experience of the generalized anxiety disorder working group

The ENIGMA group on Generalized Anxiety Disorder (ENIGMA-Anxiety/GAD) is part of a broader effort to investigate anxiety disorders using imaging and genetic data across multiple sites worldwide. The group is actively conducting a mega-analysis of a large number of brain structural scans. In this process, the group was confronted with many methodological challenges related to study planning and implementation, between-country transfer of subject-level data, quality control of a considerable amount of imaging data, and choices related to statistical methods and efficient use of resources. This report summarizes the background information and rationale for the various methodological decisions, as well as the approach taken to implement them. The goal is to document the approach and help guide other research groups working with large brain imaging data sets as they develop their own analytic pipelines for mega-analyses.

Cortical and subcortical brain structure in generalized anxiety disorder: findings from 28 research sites in the ENIGMA-Anxiety Working Group

The goal of this study was to compare brain structure between individuals with generalized anxiety disorder (GAD) and healthy controls. Previous studies have generated inconsistent findings, possibly due to small sample sizes, or clinical/analytic heterogeneity. To address these concerns, we combined data from 28 research sites worldwide through the ENIGMA-Anxiety Working Group, using a single, pre-registered mega-analysis. Structural magnetic resonance imaging data from children and adults (5-90 years) were processed using FreeSurfer. The main analysis included the regional and vertex-wise cortical thickness, cortical surface area, and subcortical volume as dependent variables, and GAD, age, age-squared, sex, and their interactions as independent variables. Nuisance variables included IQ, years of education, medication use, comorbidities, and global brain measures. The main analysis (1020 individuals with GAD and 2999 healthy controls) included random slopes per site and random intercepts per scanner. A secondary analysis (1112 individuals with GAD and 3282 healthy controls) included fixed slopes and random intercepts per scanner with the same variables. The main analysis showed no effect of GAD on brain structure, nor interactions involving GAD, age, or sex. The secondary analysis showed increased volume in the right ventral diencephalon in male individuals with GAD compared to male healthy controls, whereas female individuals with GAD did not differ from female healthy controls. This mega-analysis combining worldwide data showed that differences in brain structure related to GAD are small, possibly reflecting heterogeneity or those structural alterations are not a major component of its pathophysiology.

Antidepressant Prescribing by Pediatricians: A Mixed-Methods Analysis

Among pediatricians, perceived knowledge of efficacy, tolerability, dosing, and side effects of antidepressants represent significant sources of variability in the use of these medications in youth with depressive and anxiety disorders. Importantly, the qualitative factors that relate to varying levels of comfort with antidepressants and willingness to prescribe are poorly understood. Using a mixed-methods approach, in-depth interviews were conducted with community-based and academic medical center-based pediatricians (N = 14). Interviews were audio recorded and iteratively coded; themes were then generated using inductive thematic analysis. The relationship between demographic factors, knowledge of antidepressants, dosing, and side effects, as well as prescribing likelihood scores for depressive disorders, anxiety disorders or co-morbid anxiety and depressive disorders, were evaluated using mixed models. Pediatricians reported antidepressants to be effective and well-tolerated. However, the likelihood of individual physicians initiating an antidepressant was significantly lower for anxiety disorders relative to depressive disorders with similar functional impairment. Pediatricians considered symptom severity/functional impairment, age and the availability of psychotherapy as they considered prescribing antidepressants to individual patients. Antidepressant choice was related to the physician׳s perceived knowledge and comfort with a particular antidepressant, financial factors, and the disorder-specific evidence base for that particular medication and consultation with mental health practitioners. Pediatricians noted similar efficacy and tolerability profiles for antidepressants in youth with depressive disorders and anxiety disorders, but tended to utilize "therapy first" approaches for anxiety disorders relative to depressive disorders. Parental and family factors that influenced prescribing of antidepressants by pediatricians included parental ambivalence, family-related dysfunction and impairment secondary to the child׳s psychopathology as well as the child׳s psychosocial milieu. Pediatricians consider patient- and family-specific challenges when choosing prescribing antidepressant medications and are, in general, less likely to prescribe antidepressants for youth with anxiety disorders compared to youth with depressive disorders. The lower likelihood of prescribing antidepressants for anxious youth is not related to perception of the efficacy or tolerability, but rather to a perception that anxiety disorders are less impairing and more appropriately managed with psychotherapy.

Bridging Anxiety and Depression: A Network Approach in Anxious Adolescents

BACKGROUND

The phenomenology and neurobiology of depressive symptoms in anxious youth is poorly understood.

METHODS

Association networks of anxiety and depressive symptoms were developed in adolescents with generalized anxiety disorder (GAD; N=52, mean age: 15.4±1.6 years) who had not yet developed major depressive disorder. Community analyses were used to create consensus clusters of depressive and anxiety symptoms and to identify "bridge" symptoms between the clusters. In a subset of this sample (n=39), correlations between cortical thickness and depressive symptom severity was examined.

RESULTS

Ten symptoms clustered into an anxious community, 5 clustered into a depressive community and 5 bridged the two communities: impaired schoolwork, excessive weeping, low self-esteem, disturbed appetite, and physical symptoms of depression. Patients with more depressive cluster burden had altered cortical thickness in prefrontal, inferior and medial parietal (e.g., precuneus, supramarginal) regions and had decreases in cortical thickness-age relationships in prefrontal, temporal and parietal cortices.

LIMITATIONS

Data are cross-sectional and observational. Limited sample size precluded secondary analysis of comorbidities and demographics.

CONCLUSIONS

In youth with GAD, a sub-set of symptoms not directly related to anxiety bridge anxiety and depression. Youth with greater depressive cluster burden had altered cortical thickness in cortical structures within the default mode and central executive networks. These alternations in cortical thickness may represent a distinct neurostructural fingerprint in anxious youth with early depressive symptoms. Finally, youth with GAD and high depressive symptoms had reduced age-cortical thickness correlations. The emergence of depressive symptoms in early GAD and cortical development may have bidirectional, neurobiological relationships.

Acid-sensing T cell death associated gene-8 receptor expression in panic disorder

BACKGROUND

While disruption of acid-base homeostasis has been pathoetiologically implicated in panic disorder (PD), the mechanism by which pH imbalance is translated to panic pathophysiology is poorly understood. Recently, in a translational rodent model of PD, we reported a role of microglial acid sensing G-protein coupled receptor, T cell death associated gene-8 (TDAG8) in panic-associated behavior and physiology. However, the clinical validity of the TDAG8 receptor has not been investigated.

OBJECTIVE

To assess TDAG8 in PD, we evaluated TDAG8 receptor expression in adolescents and young adults with PD and healthy comparison subjects.

METHODS

Relative expression of TDAG8 mRNA was determined in peripheral blood mononuclear cells from patients with PD, and compared to expression in healthy subjects. Linear models were utilized to evaluate the relationship between TDAG8 expression and panic disorder symptom severity scale (PDSS) score as well as other potential explanatory variables (e.g., CRP, body mass index, sex, age). Models were refined based on the estimated parameter significance, evidence of omitted variable bias and Bayesian/Akaike information criteria.

RESULTS

Relative to healthy comparison subjects (n=17), expression of TDAG8 mRNA was significantly increased in patients with PD (n=15) (1.60±0.65 vs. 1.01±0.50, p=0.008). TDAG8 mRNA expression predicted PD symptom severity in a fixed effect model incorporating age and sex (p=0.003).

CONCLUSIONS

Collectively, our results suggest greater TDAG8 expression in patients with PD compared to healthy subjects, and directly link TDAG8 expression and the severity of the PD symptoms. Further investigation of the TDAG8 receptor in panic pathophysiology is warranted.

Pharmacogenetically Guided Escitalopram Treatment for Pediatric Anxiety Disorders: Protocol for a Double-Blind Randomized Trial

Current pharmacologic treatments for pediatric anxiety disorders (e.g., selective serotonin reuptake inhibitors (SSRIs)) frequently use "one size fits all" dosing strategies based on average responses in clinical trials. However, for some SSRIs, including escitalopram, variation in CYP2C19 activity produces substantial variation in medication exposure (i.e., blood medication concentrations). This raises an important question: would refining current SSRI dosing strategies based on CYP2C19 phenotypes increase response and reduce side effect burden? To answer this question, we designed a randomized, double-blind trial of adolescents 12-17 years of age with generalized, separation, and/or social anxiety disorders (N = 132). Patients are randomized (1:1) to standard escitalopram dosing or dosing based on validated CYP2C19 phenotypes for escitalopram metabolism. Using this approach, we will determine whether pharmacogenetically-guided treatment-compared to standard dosing-produces faster and greater reduction in anxiety symptoms (i.e., response) and improves tolerability (e.g., decreased risk of treatment-related activation and weight gain). Secondarily, we will examine pharmacodynamic variants associated with treatment outcomes, thus enhancing clinicians' ability to predict response and tolerability. Ultimately, developing a strategy to optimize dosing for individual patients could accelerate response while decreasing side effects-an immediate benefit to patients and their families. ClinicalTrials.gov Identifier: NCT04623099.

Acute Neurofunctional Effects of Escitalopram in Pediatric Anxiety: A Double-Blind, Placebo-Controlled Trial

OBJECTIVE

Amygdala-ventrolateral prefrontal cortex (VLPFC) circuitry is disrupted in pediatric anxiety disorders, yet how selective serotonin reuptake inhibitors (SSRIs) affect this circuitry is unknown. We examined the impact of the SSRI escitalopram on functional connectivity (FC) within this circuit, and whether early FC changes predicted treatment response in adolescents with generalized anxiety disorder (GAD).

METHOD

Resting-state functional magnetic resonance (MR) images were acquired before and after 2 weeks of treatment in 41 adolescents with GAD (12-17 years of age) who received double-blind escitalopram or placebo for 8 weeks. Change in amygdala-based whole-brain FC and anxiety severity were analyzed.

RESULTS

Controlling for age, sex, and pretreatment anxiety, escitalopram increased amygdala-VLPFC connectivity compared to placebo (F = 17.79, p = .002 FWE-corrected). This early FC change predicted 76.7% of the variability in improvement trajectory in patients who received escitalopram (p < .001) but not placebo (p = .169); the predictive power of early amygdala-VLPFC FC change significantly differed between placebo and escitalopram (p = .013). Furthermore, this FC change predicted improvement better than baseline FC or clinical/demographic characteristics. Exploratory analyses of amygdala subfields' FC revealed connectivity of left basolateral amygdala (BLA) -VLPFC (F = 19.64, p < .001 FWE-corrected) and superficial amygdala-posterior cingulate cortex (F = 22.92, p = .001 FWE-corrected) were also increased by escitalopram, but only BLA-VLPFC FC predicted improvement in anxiety over 8 weeks of treatment.

CONCLUSION

In adolescents with GAD, escitalopram increased amygdala-prefrontal connectivity within the first 2 weeks of treatment, and the magnitude of this change predicted subsequent clinical improvement. Early normalization of amygdala-VLPFC circuitry might represent a useful tool for identifying future treatment responders as well as a promising biomarker for drug development.

CLINICAL TRIAL REGISTRATION INFORMATION

Neurofunctional Predictors of Escitalopram Treatment Response in Adolescents With Anxiety; https://www.clinicaltrials.gov/; NCT02818751.

Pediatric anxiety and daily fine particulate matter: A longitudinal study

Daily variations in ambient fine particulate matter (PM_2.5) could contribute to the morbidity of anxiety disorders in children and adolescents, but has not yet been studied longitudinally at a daily level. We tested this association using repeated weekly measures of anxiety symptom severity in a group of 23 adolescents with generalized anxiety disorder. After estimating ambient PM_2.5 concentrations using a validated model, we found that increased concentrations were significantly associated with increased anxiety symptom severity and frequency two, three, and four days later. PM_2.5 may be a novel, modifiable exposure that could inform population level interventions to decrease psychiatric morbidity.

Gastrointestinal Symptoms in Pediatric Patients with Anxiety Disorders and Their Relationship to Selective Serotonin Reuptake Inhibitor Treatment or Placebo

Gastrointestinal symptoms are commonly reported as adverse effects of selective serotonin reuptake inhibitors (SSRIs), the first-line pharmacologic treatment for pediatric anxiety disorders; however, the temporal course of these symptoms during treatment, although believed to be transient, has never been prospectively evaluated. Additionally, rates of gastrointestinal symptoms and functional gastrointestinal syndromes in anxious youth are poorly understood. We examined gastrointestinal symptoms in youth with anxiety disorders during a double-blind, placebo-controlled trial of escitalopram (n = 51). Then, in a separate sample of prospectively treated children and adolescents with generalized, social and/or separation anxiety disorders (n = 56), we examined the frequency of gastrointestinal symptoms based on the Questionnaire on Pediatric Gastrointestinal Symptoms (QPGS) and ROME III criteria and the association of these symptoms with clinical and demographic characteristics using logistic regression. The frequency/severity of abdominal pain, diarrhea, bloating constipation or total gastrointestinal symptoms did not differ between patients receiving placebo (n = 25) or escitalopram (n = 26). However, escitalopram-treated youth had transient changes in nausea/vomiting and total upper gastrointestinal symptoms during the first two weeks of treatment. ROME III criteria for functional gastrointestinal syndromes were present in 12/56 patients (21.4%). QPGS-related functional gastrointestinal syndromes and symptoms were unrelated to treatment, treatment type, or clinical or demographic variables. Gastrointestinal symptoms are common in youth with anxiety and SSRIs produce transient-rather than sustained-gastrointestinal symptoms. Assessing gastrointestinal symptoms prior to pharmacotherapy and discussing factors that increase (or decrease) the likelihood of transient SSRI-related symptoms in youth may decrease patient uncertainty related to side effects and decrease medication-related anxiety.

The Impact of COVID-19 Infection and Characterization of Long COVID in Adolescents With Anxiety Disorders: A Prospective Longitudinal Study

While the coronavirus disease 2019 (COVID-19) pandemic has profoundly impacted pediatric mental health, the impact of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection on youth with anxiety disorders has not been prospectively examined. Further, there are limited prospective data on post-acute sequelae COVID-19, including symptoms that constitute the long COVID neuropsychiatric syndrome. In December 2019, we began a longitudinal study of adolescents aged 12-17 years with DSM-5 primary anxiety disorders treated with either duloxetine or escitalopram. Assessments included all items from the Generalized Anxiety Disorder-7 (GAD-7) and Quick Inventory of Depressive Symptomatology (QIDS) scales at each week and a weekly clinician-rated Clinical Global Impressions-Severity (CGI-S) scale. We examined the longitudinal course of anxiety, including following laboratory-confirmed SARS-CoV-2 infection in affected adolescents. This prospective study of the longitudinal impact of COVID-19 in pediatric anxiety disorders reveals that COVID-19 is associated with worsening anxiety symptoms and a disquieting 33% worsening in syndromic severity. Further, these data raise the possibility that, in anxious youth, COVID-19 is associated with a surfeit of neuropsychiatric symptoms.

Electronically Monitored Antidepressant Adherence in Adolescents with Anxiety Disorders: A Pilot Study

Background: Antidepressant medication adherence patterns are inconsistent in adolescents with anxiety and related disorders, and the clinical and demographic features predicting adherence are poorly understood. Methods: In an ongoing single-site prospective trial involving adolescents (aged 12-17) with the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition anxiety disorders treated with escitalopram, adherence was measured for 12 weeks using electronic monitoring caps. Adherence patterns were examined using qualitative and unsupervised clustering approaches, and predictors of adherence were evaluated using logistic regression, with demographic (age, sex, and race) and clinical variables (e.g., anxiety severity [Pediatric Anxiety Rating Scale], irritability [Affective Reactivity Index], depressive symptoms [Children's Depression Rating Scale]). Results: Among adolescents (N = 33) aged 14.5 ± 1.8 years (64% female), four adherence patterns were identified: persistent adherence, intermittent adherence, early adherence-late nonadherence, and nonadherence. In a logistic model of a 5-day moving average measure of adherence, social anxiety disorder (β = -0.68 ± 0.19, p = 0.002) and separation anxiety disorder (β = -0.61 ± 0.18, p < 0.001) were associated with lower adherence. In contrast, panic disorder, attention-deficit/hyperactivity disorder, generalized anxiety disorder, and depressive symptoms were not associated with adherence. Baseline anxiety severity was linked to lower adherence (β = -0.199 ± 0.05, p < 0.001). Older age also reduced adherence (β = -0.342 ± 0.05, p < 0.001), with each additional year of age increasing time spent nonadherent by 5% (p < 0.001). Being female (β = 0.451 ± 0.17, p = 0.011) and expecting treatment to be efficacious (β = 0.092 ± 0.04, p = 0.011) increased adherence, while greater irritability was associated with nonadherence (β = -0.075 ± 0.03, p = 0.006). Conclusions: Antidepressant adherence is variable, with distinct patterns, and those with social and separation anxiety disorders were less likely to be adherent. Factors such as older age, severe anxiety, and greater irritability predicted lower adherence, while being female and expecting treatment efficacy were associated with better adherence. Interventions that address specific symptoms or enhance treatment expectations may improve adherence.

Executive Functioning in Pediatric Anxiety and Its Relationship to Selective Serotonin Reuptake Inhibitor Treatment Response: A Double-Blind, Placebo-Controlled Trial

Objective: To characterize executive function in adolescents with generalized anxiety disorder (GAD) and its relationship to treatment. Methods: Using data from a double-blind, placebo-controlled trial of escitalopram in adolescents (N = 51) 12-17 years of age with GAD, we used the self-report version of the Behavior Rating Inventory of Executive Function (BRIEF-SR) to assess executive function, at baseline, and examined its relationship to treatment response as measured by the Pediatric Anxiety Rating Scale (PARS). Results: For all baseline subscores of the BRIEF-SR, T-scores were significantly elevated in adolescents with GAD compared to an age- and sex-matched normative healthy sample. In escitalopram-treated patients, baseline BRIEF-SR scores for Emotional Control (β = 0.256, 95% credibility interval [CrI]: 0.367 to 0.146, p < 0.001), Working Memory (β = 0.204, CrI: 0.2952 to 0.1134, p < 0.001), Planning/Organizing (β = -0.223, CrI: -0.1021 to -0.3436, p = 0.004), and Task Completion (β = -0.152, CrI: 0.075 to 0.228, p = 0.002) predicted the trajectory of improvement in PARS score over the 8-week trial. For youth who received placebo, only the Inhibit score was significantly, but weakly, associated with response trajectory (β = -0.081, CrI: -0.0167 to -0.1461, p = 0.015). For adolescents who had clinically significant impairment in Emotional Control, Working Memory, Planning/Organizing, and Task Completion (i.e., T-score >65), the trajectory of improvement significantly differed from patients without scores in the clinically significant range. Conclusions: Taken together, these findings point to the potential value of assessing executive function in youth with anxiety disorders as one strategy for guiding treatment selection. These data suggest that executive function may predict treatment response to psychopharmacologic treatment and point to numerous avenues for further personalizing treatment.

The Generalized Anxiety Disorder 7-item scale in adolescents with generalized anxiety disorder: Signal detection and validation

BACKGROUND

In pediatric patients with anxiety disorders, existing symptom inventories are either not freely available or require extensive time and effort to administer. We sought to evaluate a brief self-report scale-the Generalized Anxiety Disorder 7-item scale (GAD-7)-in adolescents with generalized anxiety disorder (GAD).

METHODS

The Pediatric Anxiety Rating Scale (PARS) and the GAD-7 were administered to youth with GAD (confirmed by structured interview). Relationships between the measures were assessed, and sensitivity and specificity was determined with regard to a global symptom severity measure (Clinical Global Impression-Severity).

RESULTS

In adolescents with GAD (N = 40; mean age, 14.8 ± 2.8), PARS and GAD-7 scores strongly correlated (R = 0.65, P ≤ .001) and a main effect for symptom severity was observed (P ≤ .001). GAD-7 scores ≥11 and ≥17 represented the optimum specificity and sensitivity for detecting moderate and severe anxiety, respectively.

CONCLUSIONS

The PARS and GAD-7 similarly reflect symptom severity. The GAD-7 is associated with acceptable specificity and sensitivity for detecting clinically significant anxiety symptoms. GAD-7 scores may be used to assess anxiety symptoms and to differentiate between mild and moderate GAD in adolescents, and may be more efficient than the PARS.