Genome-wide association analyses identify 95 risk loci and provide insights into the neurobiology of post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) genetics are characterized by lower discoverability than most other psychiatric disorders. The contribution to biological understanding from previous genetic studies has thus been limited. We performed a multi-ancestry meta-analysis of genome-wide association studies across 1,222,882 individuals of European ancestry (137,136 cases) and 58,051 admixed individuals with African and Native American ancestry (13,624 cases). We identified 95 genome-wide significant loci (80 new). Convergent multi-omic approaches identified 43 potential causal genes, broadly classified as neurotransmitter and ion channel synaptic modulators (for example, GRIA1, GRM8 and CACNA1E), developmental, axon guidance and transcription factors (for example, FOXP2, EFNA5 and DCC), synaptic structure and function genes (for example, PCLO, NCAM1 and PDE4B) and endocrine or immune regulators (for example, ESR1, TRAF3 and TANK). Additional top genes influence stress, immune, fear and threat-related processes, previously hypothesized to underlie PTSD neurobiology. These findings strengthen our understanding of neurobiological systems relevant to PTSD pathophysiology, while also opening new areas for investigation.

Discovery of 95 PTSD loci provides insight into genetic architecture and neurobiology of trauma and stress-related disorders

Posttraumatic stress disorder (PTSD) genetics are characterized by lower discoverability than most other psychiatric disorders. The contribution to biological understanding from previous genetic studies has thus been limited. We performed a multi-ancestry meta-analysis of genome-wide association studies across 1,222,882 individuals of European ancestry (137,136 cases) and 58,051 admixed individuals with African and Native American ancestry (13,624 cases). We identified 95 genome-wide significant loci (80 novel). Convergent multi-omic approaches identified 43 potential causal genes, broadly classified as neurotransmitter and ion channel synaptic modulators (e.g., GRIA1, GRM8, CACNA1E ), developmental, axon guidance, and transcription factors (e.g., FOXP2, EFNA5, DCC ), synaptic structure and function genes (e.g., PCLO, NCAM1, PDE4B ), and endocrine or immune regulators (e.g., ESR1, TRAF3, TANK ). Additional top genes influence stress, immune, fear, and threat-related processes, previously hypothesized to underlie PTSD neurobiology. These findings strengthen our understanding of neurobiological systems relevant to PTSD pathophysiology, while also opening new areas for investigation.

Phenotypic predictors of suicide subtypes from pre-to postdeployment in active duty military personnel

Military service members are at increased risk for suicide, but there are few strategies for detecting those who are at highest risk after a deployment. Using all available data collected from 4119 Military service members before and after their deployment to Iraq for Operation Iraqi Freedom, we tested whether predeployment characteristics clustered together to predict postdeployment suicidal risk. Latent class analysis showed that three classes best characterized the sample at predeployment. Class 1 had significantly higher scores on PTSD severity pre- and postdeployment than Classes 2 and 3 (Ps < .001). At postdeployment, Class 1 also had a greater proportion of endorsement of lifetime and past year suicidal ideation than Classes 2 and 3 (Ps < .05) and a greater proportion of lifetime suicide attempts than Class 3 (P < .001). Class 1 also had a greater proportion of endorsement of past-30-days intention to act on suicidal thoughts than Classes 2 and 3 (Ps < .05) and past-30-days specific plan for suicide than Classes 2 and 3 (Ps < .05). The study showed that based only on predeployment data, it is possible to determine which service members might be at highest risk for suicidal ideation and behavior at postdeployment.

Prevalence of Fibromyalgia Syndrome in Active-Duty Military Personnel

OBJECTIVE

Previous research with civilian populations has found strong associations between fibromyalgia (FM) and posttraumatic stress disorder (PTSD). We undertook this study to investigate the prevalence of FM in military service members with and without PTSD.

METHODS

Participants were active duty military personnel recruited into either an epidemiologic cohort study of service members before a military deployment or 1 of 3 PTSD treatment trials. Instruments used to document FM and PTSD included the PTSD Checklist-Stressor-Specific Version, the PTSD Symptom Scale-Interview, and the 2012 American College of Rheumatology FM questionnaire.

RESULTS

Across the 4 studies, 4,376 subjects completed surveys. The prevalence of FM was 2.9% in the predeployment cohort, and the prevalence was significantly higher in individuals with PTSD (10.8%) compared with those without PTSD (0.8%). In the treatment trials, all of the participants met criteria for PTSD before starting treatment, and the prevalence of FM was 39.7%.

CONCLUSION

The prevalence of FM in active duty service members preparing to deploy is similar to that reported for the general population of the US but is higher than expected for a predominantly male cohort. Furthermore, the prevalence of FM was significantly higher in service members with comorbid PTSD and was highest among those seeking treatment for PTSD. Further investigation is needed to determine the factors linking PTSD and FM.

Massed vs Intensive Outpatient Prolonged Exposure for Combat-Related Posttraumatic Stress Disorder: A Randomized Clinical Trial

IMPORTANCE

Improved, efficient, and acceptable treatments are needed for combat-related posttraumatic stress disorder (PTSD).

OBJECTIVE

To determine the efficacy of 2 compressed prolonged exposure (PE) therapy outpatient treatments for combat-related PTSD.

DESIGN, SETTING, AND PARTICIPANTS

This randomized clinical trial was conducted among military personnel and veterans at 4 sites in Texas from 2017 to 2019. Assessors were blinded to conditions. Data were analyzed from November 2020 to October 2022.

INTERVENTIONS

The interventions were massed-PE, which included 15 therapy sessions of 90 minutes each over 3 weeks, vs intensive outpatient program PE (IOP-PE), which included 15 full-day therapy sessions over 3 weeks with 8 treatment augmentations. The IOP-PE intervention was hypothesized to be superior to massed-PE.

MAIN OUTCOMES AND MEASURES

Coprimary outcomes included the Clinician-Administered PTSD Scale for Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) (DSM-5) (CAPS-5) and the PTSD Checklist for DSM-5 (PCL-5) administered at baseline and posttreatment follow-ups. Measures ranged from 0 to 80, with higher scores indicating greater severity. Diagnostic remission and reliable change were secondary outcomes.

RESULTS

Among 319 military personnel and veterans screened, 234 were randomized (mean [SD] age, 39.20 [7.72] years; 182 [78%] male participants), with 117 participants randomized to IOP-PE and 117 participants randomized to massed-PE. A total of 61 participants (26%) were African American, 58 participants (25%) were Hispanic, and 102 participants (44%) were White; 151 participants (65%) were married. Linear mixed-effects models found that CAPS-5 scores decreased in both treatment groups at the 1-month follow-up (IOP-PE: mean difference, -13.85 [95% CI, -16.47 to -11.23]; P < .001; massed-PE: mean difference, -14.13 [95% CI, -16.63 to -11.62]; P < .001). CAPS-5 change scores differed from 1- to 6-month follow-ups (mean difference, 4.44 [95% CI, 0.89 to 8.01]; P = .02). PTSD symptoms increased in massed-PE participants during follow-up (mean difference, 3.21 [95% CI, 0.65 to 5.77]; P = .01), whereas IOP-PE participants maintained treatment gains (mean difference, 1.23 [95% CI, -3.72 to 1.27]; P = .33). PCL-5 scores decreased in both groups from baseline to 1-month follow-up (IOP-PE: mean difference, -21.81 [95% CI, -25.57 to -18.04]; P < .001; massed-PE: mean difference, -19.96 [95% CI, -23.56 to -16.35]; P < .001) and were maintained at 6 months (IOP-PE: mean change, -0.21 [95% CI, -3.47 to 3.06]; P = .90; massed-PE: mean change, 3.02 [95% CI, -0.36 to 6.40]; P = .08). Both groups had notable PTSD diagnostic remission at posttreatment (IOP-PE: 48% [95% CI, 36% to 61%] of participants; massed-PE: 62% [95% CI, 51% to 73%] of participants), which was maintained at 6 months (IOP-PE: 53% [95% CI, 40% to 66%] of participants; massed-PE: 52% [95% CI, 38% to 66%] of participants). Most participants demonstrated reliable change on the CAPS-5 (61% [95% CI, 52% to 69%] of participants) and the PCL-5 (74% [95% CI, 66% to 81%] of participants) at the 1-month follow-up.

CONCLUSIONS AND RELEVANCE

These findings suggest that PE can be adapted into compressed treatment formats that effectively reduce PTSD symptoms.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03529435.

Decoding Shared Versus Divergent Transcriptomic Signatures Across Cortico-Amygdala Circuitry in PTSD and Depressive Disorders

OBJECTIVE

Posttraumatic stress disorder (PTSD) is a debilitating neuropsychiatric disease that is highly comorbid with major depressive disorder (MDD) and bipolar disorder. The overlap in symptoms is hypothesized to stem from partially shared genetics and underlying neurobiological mechanisms. To delineate conservation between transcriptional patterns across PTSD and MDD, the authors examined gene expression in the human cortex and amygdala in these disorders.

METHODS

RNA sequencing was performed in the postmortem brain of two prefrontal cortex regions and two amygdala regions from donors diagnosed with PTSD (N=107) or MDD (N=109) as well as from neurotypical donors (N=109).

RESULTS

The authors identified a limited number of differentially expressed genes (DEGs) specific to PTSD, with nearly all mapping to cortical versus amygdala regions. PTSD-specific DEGs were enriched in gene sets associated with downregulated immune-related pathways and microglia as well as with subpopulations of GABAergic inhibitory neurons. While a greater number of DEGs associated with MDD were identified, most overlapped with PTSD, and only a few were MDD specific. The authors used weighted gene coexpression network analysis as an orthogonal approach to confirm the observed cellular and molecular associations.

CONCLUSIONS

These findings provide supporting evidence for involvement of decreased immune signaling and neuroinflammation in MDD and PTSD pathophysiology, and extend evidence that GABAergic neurons have functional significance in PTSD.

Dose-related effects of ketamine for antidepressant-resistant symptoms of posttraumatic stress disorder in veterans and active duty military: a double-blind, randomized, placebo-controlled multi-center clinical trial

This study tested the efficacy of repeated intravenous ketamine doses to reduce symptoms of posttraumatic stress disorder (PTSD). Veterans and service members with PTSD (n = 158) who failed previous antidepressant treatment were randomized to 8 infusions administered twice weekly of intravenous placebo (n = 54), low dose (0.2 mg/kg; n = 53) or standard dose (0.5 mg/kg; n = 51) ketamine. Participants were assessed at baseline, during treatment, and for 4 weeks after their last infusion. Primary analyses used mixed effects models. The primary outcome measure was the self-report PTSD Checklist for DSM-5 (PCL-5), and secondary outcome measures were the Clinician-Administered PTSD Scale for DSM-5 (CAPS-5) and the Montgomery Åsberg Depression Rating Scale (MADRS). There were no significant group-by-time interactions for PTSD symptoms measured by the PCL-5 or CAPS-5. The standard ketamine dose ameliorated depression measured by the MADRS significantly more than placebo. Ketamine produced dose-related dissociative and psychotomimetic effects, which returned to baseline within 2 h and were less pronounced with repeated administration. There was no evidence of differential treatment discontinuation by ketamine dose, consistent with good tolerability. This clinical trial failed to find a significant dose-related effect of ketamine on PTSD symptoms. Secondary analyses suggested that the standard dose exerted rapid antidepressant effects. Further studies are needed to determine the role of ketamine in PTSD treatment. ClinicalTrials.gov identifier: NCT02655692.

Enhancing Discovery of Genetic Variants for Posttraumatic Stress Disorder Through Integration of Quantitative Phenotypes and Trauma Exposure Information

BACKGROUND

Posttraumatic stress disorder (PTSD) is heritable and a potential consequence of exposure to traumatic stress. Evidence suggests that a quantitative approach to PTSD phenotype measurement and incorporation of lifetime trauma exposure (LTE) information could enhance the discovery power of PTSD genome-wide association studies (GWASs).

METHODS

A GWAS on PTSD symptoms was performed in 51 cohorts followed by a fixed-effects meta-analysis (N = 182,199 European ancestry participants). A GWAS of LTE burden was performed in the UK Biobank cohort (N = 132,988). Genetic correlations were evaluated with linkage disequilibrium score regression. Multivariate analysis was performed using Multi-Trait Analysis of GWAS. Functional mapping and annotation of leading loci was performed with FUMA. Replication was evaluated using the Million Veteran Program GWAS of PTSD total symptoms.

RESULTS

GWASs of PTSD symptoms and LTE burden identified 5 and 6 independent genome-wide significant loci, respectively. There was a 72% genetic correlation between PTSD and LTE. PTSD and LTE showed largely similar patterns of genetic correlation with other traits, albeit with some distinctions. Adjusting PTSD for LTE reduced PTSD heritability by 31%. Multivariate analysis of PTSD and LTE increased the effective sample size of the PTSD GWAS by 20% and identified 4 additional loci. Four of these 9 PTSD loci were independently replicated in the Million Veteran Program.

CONCLUSIONS

Through using a quantitative trait measure of PTSD, we identified novel risk loci not previously identified using prior case-control analyses. PTSD and LTE have a high genetic overlap that can be leveraged to increase discovery power through multivariate methods.

Testing the role of aerobic exercise in the treatment of posttraumatic stress disorder (PTSD) symptoms in U.S. active duty military personnel: a pilot study

The purpose of this pilot study was to determine if the efficacy of imaginal exposure for symptoms of posttraumatic stress disorder (PTSD) could be improved by adding aerobic exercise. We hypothesized that aerobic exercise would enhance the efficacy of exposure therapy. Active duty service members with clinically significant symptoms of posttraumatic stress (PTSD Checklist-Stressor-Specific Version, [PCL-S], ≥25) were randomized into one of four conditions: exercise only; imaginal exposure only; imaginal exposure plus exercise; no exercise/no exposure therapy (control). Participants (N = 72) were primarily male, Army, noncommissioned officers ranging in age from 22 to 52. PTSD symptom severity decreased over time (p < .0001); however, there were no significant differences between the experimental conditions. The prediction that imaginal exposure augmented with aerobic exercise would be superior to either imaginal exposure alone or aerobic exercise alone was not supported, suggesting that engaging in exercise and imaginal exposure simultaneously may not be any better than engaging in either activity alone. A better understanding of individually administered and combined exercise and exposure therapy interventions for PTSD is warranted.

Gene expression in the dorsolateral and ventromedial prefrontal cortices implicates immune-related gene networks in PTSD

Studies evaluating neuroimaging, genetically predicted gene expression, and pre-clinical genetic models of PTSD, have identified PTSD-related abnormalities in the prefrontal cortex (PFC) of the brain, particularly in dorsolateral and ventromedial PFC (dlPFC and vmPFC). In this study, RNA sequencing was used to examine gene expression in the dlPFC and vmPFC using tissue from the VA National PTSD Brain Bank in donors with histories of PTSD with or without depression (dlPFC n = 38, vmPFC n = 35), depression cases without PTSD (n = 32), and psychopathology-free controls (dlPFC n = 24, vmPFC n = 20). Analyses compared PTSD cases to controls. Follow-up analyses contrasted depression cases to controls. Twenty-one genes were differentially expressed in PTSD after strict multiple testing correction. PTSD-associated genes with roles in learning and memory (FOS, NR4A1), immune regulation (CFH, KPNA1) and myelination (MBP, MOBP, ERMN) were identified. PTSD-associated genes partially overlapped depression-associated genes. Co-expression network analyses identified PTSD-associated networks enriched for immune-related genes across the two brain regions. However, the immune-related genes and association patterns were distinct. The immune gene IL1B was significantly associated with PTSD in candidate-gene analysis and was an upstream regulator of PTSD-associated genes in both regions. There was evidence of replication of dlPFC associations in an independent cohort from a recent study, and a strong correlation between the dlPFC PTSD effect sizes for significant genes in the two studies (r = 0.66, p < 2.2 × 10⁻¹⁶). In conclusion, this study identified several novel PTSD-associated genes and brain region specific PTSD-associated immune-related networks.

STRONG STAR and the Consortium to Alleviate PTSD: Shaping the future of combat PTSD and related conditions in military and veteran populations

The STRONG STAR Consortium (South Texas Research Organizational Network Guiding Studies on Trauma and Resilience) and the Consortium to Alleviate PTSD are interdisciplinary and multi-institutional research consortia focused on the detection, diagnosis, prevention, and treatment of combat-related posttraumatic stress disorder (PTSD) and comorbid conditions in military personnel and veterans. This manuscript outlines the consortia's state-of-the-science collaborative research model and how this can be used as a roadmap for future trauma-related research. STRONG STAR was initially funded for 5 years in 2008 by the U.S. Department of Defense's (DoD) Psychological Health and Traumatic Brain Injury Research Program. Since the initial funding of STRONG STAR, almost 50 additional peer-reviewed STRONG STAR-affiliated projects have been funded through the DoD, the U.S. Department of Veterans Affairs (VA), the National Institutes of Health, and private organizations. In 2013, STRONG STAR investigators partnered with the VA's National Center for PTSD and were selected for joint DoD/VA funding to establish the Consortium to Alleviate PTSD. STRONG STAR and the Consortium to Alleviate PTSD have assembled a critical mass of investigators and institutions with the synergy required to make major scientific and public health advances in the prevention and treatment of combat PTSD and related conditions. This manuscript provides an overview of the establishment of these two research consortia, including their history, vision, mission, goals, and accomplishments. Comprehensive tables provide descriptions of over 70 projects supported by the consortia. Examples are provided of collaborations among over 50 worldwide academic research institutions and over 150 investigators.

Identifying suicidal subtypes and dynamic indicators of increasing and decreasing suicide risk in active duty military personnel: Study protocol

Objectives

Several recent studies have demonstrated that posttraumatic stress disorder (PTSD) and insomnia treatments are associated with significant reductions in suicidal ideation (SI) among service members. However, few investigations have evaluated the manner in which suicide risk changes over time among military personnel receiving PTSD or insomnia treatments. This paper describes the study protocol for a project with these aims: (1) explore potential genetic, clinical, and demographic subtypes of suicide risk in a large cohort of deployed service members; (2) explore subtype change in SI as a result of evidence-based psychotherapies for PTSD and insomnia; (3) evaluate the speed of change in suicide risk; and (4) identify predictors of higher- and lower-risk for suicide.

Methods

Active duty military personnel were recruited for four clinical trials (three for PTSD treatment and one for insomnia treatment) and a large prospective epidemiological study of deployed service members, all conducted through the South Texas Research Organizational Network Guiding Studies on Trauma and Resilience (STRONG STAR Consortium). Participants completed similar measures of demographic and clinical characteristics and subsets provided blood samples for genetic testing. The primary measures that we will analyze are the Beck Scale for Suicide Ideation, Beck Depression Inventory, and the PTSD Checklist for DSM-IV.

Discussion

Results from this study will offer new insights into the presence of discrete subtypes of suicide risk among active duty personnel, changes in risk over time among those subtypes, and predictors of subtypes. Findings will inform treatment development for military service members at risk for suicide.

Transcriptomic organization of the human brain in post-traumatic stress disorder

Despite extensive study of the neurobiological correlates of post-traumatic stress disorder (PTSD), little is known about its molecular determinants. Here, differential gene expression and network analyses of four prefrontal cortex subregions from postmortem tissue of people with PTSD demonstrate extensive remodeling of the transcriptomic landscape. A highly connected downregulated set of interneuron transcripts is present in the most significant gene network associated with PTSD. Integration of this dataset with genotype data from the largest PTSD genome-wide association study identified the interneuron synaptic gene ELFN1 as conferring significant genetic liability for PTSD. We also identified marked transcriptomic sexual dimorphism that could contribute to higher rates of PTSD in women. Comparison with a matched major depressive disorder cohort revealed significant divergence between the molecular profiles of individuals with PTSD and major depressive disorder despite their high comorbidity. Our analysis provides convergent systems-level evidence of genomic networks within the prefrontal cortex that contribute to the pathophysiology of PTSD in humans.

Neuroendocrine biomarkers of prolonged exposure treatment response in military-related PTSD

Posttraumatic stress disorder (PTSD) is associated with dysregulation of the neuroendocrine system, including cortisol, allopregnanolone, and pregnanolone. Preliminary evidence from animal models suggests that baseline levels of these biomarkers may predict response to PTSD treatment. We report the change in biomarkers over the course of PTSD treatment. Biomarkers were sampled from individuals participating in (1) a randomized controlled trial comparing a web-version of Prolonged Exposure (Web-PE) therapy to in-person Present-Centered Therapy (PCT) and (2) from individuals participating in a nonrandomized effectiveness study testing PE delivered in-person as part of an intensive outpatient PTSD program. We found that higher cortisol reactivity during script-driven imagery was associated with higher baseline PTSD severity and that baseline allopregnanolone, pregnanolone, and cortisol reactivity were associated with PTSD treatment responder status over the course of intensive outpatient treatment. These findings demonstrate that peripherally assessed biomarkers are associated with PTSD severity and likelihood of successful treatment outcome of PE delivered daily over two weeks. These assessments could be used to determine which patients are likely to respond to treatment and which patients require augmentation to increase the likelihood of optimal response to PTSD treatment.

Shared genetic etiology underlying late-onset Alzheimer's disease and posttraumatic stress syndrome

INTRODUCTION

Late-onset Alzheimer's disease (LOAD) manifests comorbid neuropsychiatric symptoms and posttraumatic stress disorder (PTSD) is associated with an increased risk for dementia in late life, suggesting the two disorders may share genetic etiologies.

METHODS

We performed genetic pleiotropy analysis using LOAD and PTSD genome-wide association study (GWAS) datasets from white and African-American populations, followed by functional-genomic analyses.

RESULTS

We found an enrichment for LOAD across increasingly stringent levels of significance with the PTSD GWAS association (LOAD|PTSD) in the discovery and replication cohorts and a modest enrichment for the reverse conditional association (PTSD|LOAD). LOAD|PTSD association analysis identified and replicated the MS4A genes region. These genes showed similar expression pattern in brain regions affected in LOAD, and across-brain-tissue analysis identified a significant association for MS4A6A. The African-American samples showed moderate enrichment; however, no false discovery rate-significant associations.

DISCUSSION

We demonstrated common genetic signatures for LOAD and PTSD and suggested immune response as a common pathway for these diseases.

International meta-analysis of PTSD genome-wide association studies identifies sex- and ancestry-specific genetic risk loci

The risk of posttraumatic stress disorder (PTSD) following trauma is heritable, but robust common variants have yet to be identified. In a multi-ethnic cohort including over 30,000 PTSD cases and 170,000 controls we conduct a genome-wide association study of PTSD. We demonstrate SNP-based heritability estimates of 5-20%, varying by sex. Three genome-wide significant loci are identified, 2 in European and 1 in African-ancestry analyses. Analyses stratified by sex implicate 3 additional loci in men. Along with other novel genes and non-coding RNAs, a Parkinson's disease gene involved in dopamine regulation, PARK2, is associated with PTSD. Finally, we demonstrate that polygenic risk for PTSD is significantly predictive of re-experiencing symptoms in the Million Veteran Program dataset, although specific loci did not replicate. These results demonstrate the role of genetic variation in the biology of risk for PTSD and highlight the necessity of conducting sex-stratified analyses and expanding GWAS beyond European ancestry populations.

The role of familial risk, parental psychopathology, and stress for first-onset depression during adolescence

BACKGROUND

Adolescence represents a critical developmental period during which the initial onset of depression emerges. Family risk for depression is a salient risk factor for the initial onset of Major Depressive Disorder (MDD). We examined the effects of familial risk, stress, and behavior on the risk of developing first-onset depression.

METHODS

Adolescents aged 12 to 15 with high (n = 166) or low (n = 159) familial risk for depression were assessed annually for up to five years. Stress was assessed using the Stressful Life Events Schedule and Childhood Trauma Questionnaire. The Kiddie Schedule for Affective Disorders and Schizophrenia-Present and Lifetime Version was administered to the adolescents and their parents to assess lifetime psychiatric conditions and diagnose MDD onset. Survival and path analyses were used in tandem to determine the risk for first-onset depression as well as the contributions of additional direct and indirect pathways to onset.

RESULTS

High-risk adolescents were eight times more likely to develop first-onset depression compared with low-risk adolescents. The path analyses revealed that the presence of maternal behavioral disorders and increased recent life stress directly predicted an initial onset of MDD in high-risk adolescents.

LIMITATIONS

The small samples used in this study limit the generalizability of these findings.

CONCLUSIONS

Adolescents at high familial risk for depression had an increased risk for the emergence of first-onset depression during adolescence. Stress and maternal behavioral psychopathology directly contributed to depression onset independently of familial risk, while childhood trauma exerted an indirect effect on first-onset MDD through recent stress.

Repeated ketamine infusions for antidepressant-resistant PTSD: Methods of a multicenter, randomized, placebo-controlled clinical trial

Posttraumatic stress disorder (PTSD) is a debilitating disorder with limited medication treatment options. Recent reports have described the dearth of research on new drug development as a crisis in the pharmacotherapy of PTSD. There are only two PTSD medications approved by the U.S. Food and Drug Administration, and both are serotonergic antidepressants. Therefore, there is a tremendous need to identify more effective and more rapidly acting pharmacotherapies for PTSD that work through novel neural mechanisms. Pilot evidence and case reports provided preliminary evidence supporting the safety and utility of investigating the therapeutic effects of ketamine in PTSD. However, the efficacy of this drug for PTSD has not yet been tested in active duty military or veteran populations. Here, we report the design and methods of a study funded under the Consortium to Alleviate PTSD. The study is a multisite, placebo-controlled, double-blind, randomized clinical trial to examine the dose-related efficacy of ketamine, as compared to placebo, in producing a rapid and sustained reduction in PTSD symptomatology in veterans and active duty military populations with antidepressant-resistant PTSD. Approximately 198 eligible participants who meet criteria for PTSD will be randomized to the study drug (i.e., ketamine 0.5 mg/kg, ketamine 0.2 mg/kg, or placebo). The study drug will be administered intravenously twice per week for 4 weeks, followed by a 4-week follow-up period. This ongoing study is the only trial of therapeutic effects of ketamine for PTSD and the first placebo-controlled trial to determine the dose-related effects of repeated ketamine on PTSD.

Frontal Lobe Circuitry in Posttraumatic Stress Disorder

Symptoms of posttraumatic stress disorder include hyperarousal, avoidance of trauma-related stimuli, re-experiencing of trauma, and mood changes. This review focuses on the frontal cortical areas that form crucial links in circuitry pertinent to posttraumatic stress disorder symptomatology: (1) the conditioned fear extinction circuit, (2) the salience circuit, and (3) the mood circuit. These frontal areas include the ventromedial prefrontal cortex (conditioned fear extinction), the dorsal anterior cingulate and insular cortices (salience), and the lateral orbitofrontal and subgenual cingulate cortices (mood). Frontal lobe structural abnormalities in posttraumatic stress disorder, including volumetric reductions in the cingulate cortices, impact all three circuits. Functional analyses of frontal cortices in posttraumatic stress disorder show abnormal activation in all three according to task demand and emotional valence. Network analyses reveal altered amygdalo-frontal connectivity and failure to suppress the default mode network during cognitive engagement. Spine shape alterations also have been detected in the medial orbito-frontal cortex in posttraumatic stress disorder postmortem brains, suggesting reduced synaptic plasticity. Importantly, frontal lobe abnormalities in posttraumatic stress disorder extend beyond emotion-related circuits to include the lateral prefrontal cortices that mediate executive functions. In conclusion, widespread frontal lobe dysfunction in posttraumatic stress disorder provides a neurobiologic basis for the core symptomatology of the disorder, as well as for executive function impairment.

Neurosteroid Levels in the Orbital Frontal Cortex of Subjects with PTSD and Controls: A Preliminary Report

Background

Neurosteroids mediate stress signaling and have been implicated in the pathogenesis of post-traumatic stress disorder (PTSD) in both preclinical and clinical studies. Compared to controls, subjects with PTSD exhibit altered neurosteroid levels in peripheral blood and cerebrospinal fluid as well as hypoactivity in the medial orbital frontal cortex (mOFC). Therefore, the aim of this study was to compare neurosteroid levels in the mOFC of subjects with PTSD (n = 18) and controls (n = 35).

Methods

Gray matter was dissected from fresh-frozen mOFC, and levels of the neurosteroids pregnenolone, allopregnanolone, pregnanolone, epiallopregnanolone, epipregnanolone, tetrahydrodeoxycorticosterone, and androsterone were determined by gas chromatography - tandem mass spectrometry (GC/MS/MS).

Results

Analyses of unadjusted levels revealed that males with PTSD had significantly decreased levels of allopregnanolone (p = 0.03) compared to control males and females with PTSD had significantly increased levels of pregnenolone (p = 0.03) relative to control females. After controlling for age, postmortem interval, and smoking status, results showed that males with PTSD had significantly decreased levels of androsterone (t46 = 2.37, p = 0.02) compared to control males and females with PTSD had significantly increased levels of pregnanolone (t46 = -2.25, p = 0.03) relative to control females.

Conclusions

To our knowledge, this is the first report of neurosteroid levels in postmortem brain tissue of subjects with PTSD. Although replication is required in other brain regions and in a larger cohort of subjects, the results suggest a dysregulation of allopregnanolone and androsterone in males with PTSD and pregnanolone in females with PTSD in the mOFC.

Intensive prolonged exposure therapy for combat-related posttraumatic stress disorder: Design and methodology of a randomized clinical trial

Combat-related posttraumatic stress disorder (PTSD) is the most common psychological health condition in military service members and veterans who have deployed to the combat theater since September 11, 2001. One of the highest research priorities for the Department of Defense and the Department of Veterans Affairs is to develop and evaluate the most efficient and efficacious treatments possible for combat-related PTSD. However, the treatment of combat-related PTSD in military service members and veterans has been significantly more challenging than the treatment of PTSD in civilians. Randomized clinical trials have demonstrated large posttreatment effect sizes for PTSD in civilian populations. However, recent randomized clinical trials of service members and veterans have achieved lesser reductions in PTSD symptoms. These results suggest that combat-related PTSD is unique. Innovative approaches are needed to augment established evidence-based treatments with targeted interventions that address the distinctive elements of combat-related traumas. This paper describes the design, methodology, and protocol of a randomized clinical trial to compare two intensive prolonged exposure therapy treatments for combat-related PTSD in active duty military service members and veterans and that can be administered in an acceptable, efficient manner in this population. Both interventions include intensive daily treatment over a 3-week period and a number of treatment enhancements hypothesized to result in greater reductions in combat-related PTSD symptoms. The study is designed to advance the delivery of care for combat-related PTSD by developing and evaluating the most potent treatments possible to reduce PTSD symptomatology and improve psychological, social, and occupational functioning.

Comparative evaluation of a new magnetic bead-based DNA extraction method from fecal samples for downstream next-generation 16S rRNA gene sequencing

We are colonized by a vast population of genetically diverse microbes, the majority of which are unculturable bacteria that reside within the gastrointestinal tract. As affordable, advanced next-generation sequencing technologies become more widely available, important discoveries about the composition and function of these microbes become increasingly possible. In addition to rapid advancement in sequencing technologies, automated systems have been developed for nucleic acid extraction; however, these methods have yet to be widely used for the isolation of bacterial DNA from fecal samples. Here, we adapted Promega’s Maxwell^® RSC PureFood GMO and Authentication kit for use with fecal samples and compared it to the commonly used Qiagen QIAamp^® PowerFecal^® kit. Results showed that the two approaches yielded similar measures of DNA purity and successful next-generation sequencing amplification and produced comparable composition of microbial communities. However, DNA extraction with the Maxwell^® RSC kit produced higher concentrations with a lower fecal sample input weight and took a fraction of the time compared to the QIAamp^® PowerFecal^® protocol. The results of this study demonstrate that the Promega Maxwell^® RSC system can be used for medium-throughput DNA extraction in a time-efficient manner without compromising the quality of the downstream sequencing.

Trajectories of Alcohol Initiation and Use During Adolescence: The Role of Stress and Amygdala Reactivity

OBJECTIVE

Early alcohol use initiation predicts onset of alcohol use disorders in adulthood. However, little is known about developmental trajectories of alcohol use initiation and their putative biological and environmental correlates.

METHOD

Adolescents (N = 330) with high or low familial loading for depression were assessed annually for up to 6 years. Data were collected assessing affective symptoms, alcohol use, and stress at each assessment. Adolescents also participated in a functional magnetic resonance imaging protocol that included measurement of threat-related amygdala and reward-related ventral striatum activity.

RESULTS

Latent class analyses identified 2 trajectories of alcohol use initiation. Early initiators (n = 32) reported greater baseline alcohol use and rate of change of use compared with late initiators and/or current abstainers (n = 298). Early initiators reported higher baseline levels of stressful life events (p = .001) and exhibited higher amygdala (p = .001) but not ventral striatum activity compared with late initiators. Early initiators were 15.3 times more likely to have a full drink (p < .0001), 9.1 times more likely to experience intoxication (p < .0001), and 6.7 times more likely to develop an alcohol use disorder by 19 years of age compared with late initiators (p = .003).

CONCLUSION

Adolescents on a trajectory of early alcohol use initiation have higher levels of stress, have increased threat-related amygdala activity, are more likely to consume a full standard alcoholic drink, are more likely to experience early intoxication, and are at a heightened risk for the onset of an alcohol use disorder.

Paradoxical associations between familial affective responsiveness, stress, and amygdala reactivity

Studies of early life extremes such as trauma, abuse, and neglect highlight the critical importance of quality caregiving in the development of brain circuits supporting emotional behavior and mental health. The impact of normative variability in caregiving on such biobehavioral processes, however, is poorly understood. Here, we provide initial evidence that even subtle variability in normative caregiving maps onto individual differences in threat-related brain function and, potentially, associated psychopathology in adolescence. Specifically, we report that greater familial affective responsiveness is associated with heightened amygdala reactivity to interpersonal threat, particularly in adolescents having experienced relatively low recent stress. These findings extend the literature on the effects of caregiving extremes on brain function to subtle, normative variability but suggest that presumably protective factors may be associated with increased risk-related amygdala reactivity. We consider these paradoxical associations with regard to studies of basic associative threat learning and further consider their relevance for understanding potential effects of caregiving on psychological development. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Inflammatory markers as predictors of depression and anxiety in adolescents: Statistical model building with component-wise gradient boosting

BACKGROUND

Immune system abnormalities have been repeatedly observed in several psychiatric disorders, including severe depression and anxiety. However, whether specific immune mediators play an early role in the etiopathogenesis of these disorders remains unknown.

METHODS

In a longitudinal design, component-wise gradient boosting was used to build models of depression, assessed by the Mood-Feelings Questionnaire-Child (MFQC), and anxiety, assessed by the Screen for Child Anxiety Related Emotional Disorders (SCARED) in 254 adolescents from a large set of candidate predictors, including sex, race, 39 inflammatory proteins, and the interactions between those proteins and time. Each model was reduced via backward elimination to maximize parsimony and generalizability.

RESULTS

Component-wise gradient boosting and model reduction found that female sex, growth- regulated oncogene (GRO), and transforming growth factor alpha (TGF-alpha) predicted depression, while female sex predicted anxiety.

LIMITATIONS

Differential onset of puberty as well as a lack of control for menstrual cycle may also have been responsible for differences between males and females in the present study. In addition, investigation of all possible nonlinear relationships between the predictors and the outcomes was beyond the computational capacity and scope of the present research.

CONCLUSIONS

This study highlights the need for novel statistical modeling to identify reliable biological predictors of aberrant psychological behavior.

Amygdala reactivity predicts adolescent antisocial behavior but not callous-unemotional traits

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Greater amygdala reactivity to angry faces predicted youth antisocial behavior.

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Callous-unemotional traits were not related to amygdala reactivity.

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Findings were similar across sex, ethnicity, and pubertal stage.

Recent neuroimaging studies have suggested divergent relationships between antisocial behavior (AB) and callous-unemotional (CU) traits and amygdala reactivity to fearful and angry facial expressions in adolescents. However, little work has examined if these findings extend to dimensional measures of behavior in ethnically diverse, non-clinical samples, or if participant sex, ethnicity, pubertal stage, and age moderate associations. We examined links between amygdala reactivity and dimensions of AB and CU traits in 220 Hispanic and non-Hispanic Caucasian adolescents (age 11–15; 49.5% female; 38.2% Hispanic), half of whom had a family history for depression and thus were at relatively elevated risk for late starting, emotionally dysregulated AB. We found that AB was significantly related to increased right amygdala reactivity to angry facial expressions independent of sex, ethnicity, pubertal stage, age, and familial risk status for depression. CU traits were not related to fear- or anger-related amygdala reactivity. The present study further demonstrates that AB is related to increased amygdala reactivity to interpersonal threat cues in adolescents, and that this relationship generalizes across sex, ethnicity, pubertal stage, age, and familial risk status for depression.

An epigenetic mechanism links socioeconomic status to changes in depression-related brain function in high-risk adolescents

Identifying biological mechanisms through which the experience of adversity emerges as individual risk for mental illness is an important step toward developing strategies for personalized treatment and, ultimately, prevention. Preclinical studies have identified epigenetic modification of gene expression as one such mechanism. Recent clinical studies have suggested that epigenetic modification, particularly methylation of gene regulatory regions, also acts to shape human brain function associated with risk for mental illness. However, it is not yet clear whether differential gene methylation as a function of adversity contributes to the emergence of individual risk for mental illness. Using prospective longitudinal epigenetic, neuroimaging and behavioral data from 132 adolescents, we demonstrate that changes in gene methylation associated with lower socioeconomic status (SES) predict changes in risk-related brain function. Specifically, we find that lower SES during adolescence is associated with an increase in methylation of the proximal promoter of the serotonin transporter gene, which predicts greater increases in threat-related amygdala reactivity. We subsequently demonstrate that greater increases in amygdala reactivity moderate the association between a positive family history for depression and the later manifestation of depressive symptoms. These initial results suggest a specific biological mechanism through which adversity contributes to altered brain function, which in turn moderates the emergence of general liability as individual risk for mental illness. If replicated, this prospective pathway may represent a novel target biomarker for intervention and prevention among high-risk individuals.

Prevalence, Correlates, and Predictors of Insomnia in the US Army prior to Deployment

STUDY OBJECTIVES

To determine the prevalence, correlates, and predictors of insomnia in US Army personnel prior to deployment.

METHODS

Cross-sectional cohort design assessing insomnia and other psychosocial variables in active duty service members (n = 4,101), at Fort Hood, Texas, prior to military deployment. Insomnia was defined as an Insomnia Severity Index ≥ 15.

RESULTS

The prevalence of insomnia was 19.9%. Enlisted personnel were five times more likely to report insomnia than officers (odds ratio [OR] = 5.17). Insomnia was higher among American Indian/Alaskan Natives than other groups (ORs = 1.86-2.85). Those in the Insomnia Group were older, had longer military careers, and reported more marriages, children, and military deployments (ds = 0.13-0.34) than the No Insomnia group. The Insomnia Group reported more severe mental health symptoms, more recent stressful life events, greater childhood abuse, and lower levels of trait resilience, social support, and unit cohesion (Cohen ds = 0.27-1.29). After controlling for covariates, the Insomnia Group was more likely to have a history of head injuries and clinically significant posttraumatic stress disorder (PTSD), anxiety, depression, alcohol use problems, back pain, extremity pain, headaches, and fatigue (ORs = 1.40-3.30). A simultaneous logistic regression found that greater PTSD, depression, fatigue, stressful life events, headaches, anxiety, alcohol use problems, extremity pain, history of head injury, childhood physical neglect, back pain, number of times married, and lower leader support/unit cohesion and tangible social support were statistically significant predictors of insomnia status.

CONCLUSIONS

Insomnia occurs in about one of five service members prior to a military deployment and is associated with a wide array of psychosocial stressors and mental and physical health problems.

Depression in Mexican Americans with diagnosed and undiagnosed diabetes

BACKGROUND

Depression and diabetes commonly co-occur; however, the strength of the physiological effects of diabetes as mediating factors towards depression is uncertain.

METHOD

We analyzed extensive clinical, epidemiological and laboratory data from n = 2081 Mexican Americans aged 35-64 years, recruited from the community as part of the Cameron County Hispanic Cohort (CCHC) divided into three groups: Diagnosed (self-reported) diabetes (DD, n = 335), Undiagnosed diabetes (UD, n = 227) and No diabetes (ND, n = 1519). UD participants denied being diagnosed with diabetes, but on testing met the 2010 American Diabetes Association and World Health Organization definitions of diabetes. Depression was measured using the Center for Epidemiological Studies - Depression (CES-D) scale. Weighted data were analyzed using dimensional and categorical outcomes using univariate and multivariate models.

RESULTS

The DD group had significantly higher CES-D scores than both the ND and UD (p ⩽ 0.001) groups, whereas the ND and UD groups did not significantly differ from each other. The DD subjects were more likely to meet the CES-D cut-off score for depression compared to both the ND and UD groups (p = 0.001), respectively. The UD group was also less likely to meet the cut-off score for depression than the ND group (p = 0.003). Our main findings remained significant in models that controlled for socio-demographic and clinical confounders.

CONCLUSIONS

Meeting clinical criteria for diabetes was not sufficient for increased depressive symptoms. Our findings suggest that the 'knowing that one is ill' is associated with depressive symptoms in diabetic subjects.

Blunted Ventral Striatum Development in Adolescence Reflects Emotional Neglect and Predicts Depressive Symptoms

BACKGROUND

Emotional neglect is associated with multiple negative outcomes, particularly increased risk for depression. Motivated by increasing evidence of reward-related ventral striatum (VS) dysfunction in depression, we investigated the role of developmental changes in VS activity on the emergence of depressive symptomatology as a function of emotional neglect.

METHODS

We examined relationships between longitudinal neuroimaging of reward-related VS activity, assessments of mood, and measures of emotional neglect in 106 participants first scanned between ages 11 to 15 and then 2 years later.

RESULTS

We found that greater levels of emotional neglect were associated with blunted development of reward-related VS activity between the first and second assessments (as indexed by lower residualized change scores). Additionally, we found that decreases in this reward-related VS activity were related to greater depressive symptomatology and partially mediated the association between emotional neglect and subsequent depressive symptomatology.

CONCLUSIONS

Our results provide an important demonstration that blunted development of reward-related VS activity as a function of emotional neglect predicts the emergence of depressive symptoms in adolescents. Further, our results are consistent with emerging evidence for the importance of reward-related VS dysfunction in the etiology and pathophysiology of depression. These results are a first step toward developing the ability to predict, prevent, and treat stress-related psychopathology through the targeting of specific neural phenotypes.

Depression, obesity, and metabolic syndrome: prevalence and risks of comorbidity in a population-based representative sample of Mexican Americans

INTRODUCTION

We examined the prevalence of depression, obesity, and metabolic syndrome and associations between them in a population-based representative cohort of Mexican Americans living on the United States-Mexico border.

METHOD

The sample in this cross-sectional analysis consisted of 1,768 Mexican American adults (≥ 18 years of age) assessed between the years 2004 and 2010, with whom we tested our central hypothesis of a significant relationship between obesity and depression. Depression was measured using the Center for Epidemiologic Studies-Depression scale (CES-D) with a cutoff score of ≥ 16 for depression and a cutoff score of ≥ 27 for severe depression. We categorized body mass index (BMI) values as obese (≥ 30kg/m(2)) and later subdivided the obese subjects into obese (30-39 kg/m(2)[inclusive]) and morbidly obese (≥ 40 kg/m(2)). Metabolic syndrome was defined using the American Heart Association definition requiring at least 3 of the following: increased waist circumference, elevated triglycerides, reduced high-density lipoprotein (HDL) cholesterol, elevated blood pressure, and elevated fasting glucose. Weighted data were analyzed to establish prevalence of depression, obesity, and metabolic syndrome. Univariate and multivariable weighted regression models were used to test potential associations between these disorders.

RESULTS

Using weighted prevalence, we observed high rates of depression (30%), obesity (52%), and metabolic syndrome (45%). Univariate models revealed female gender (P = .0004), low education (P = .003), low HDL level (P = .009), and increased waist circumference (P = .03) were associated with depression. Female gender (P = .01), low education (P = .003), and morbid obesity (P = .002) were risk factors for severe depression and remained significant in multivariable models.

CONCLUSIONS

In this large cohort of Mexican Americans, obesity, female gender, and low education were identified risk factors for depression. These indicators may serve as targets for early detection, prevention, and intervention in this population.

BA11 FKBP5 expression levels correlate with dendritic spine density in postmortem PTSD and controls

Genetic variants of the immunophilin FKBP5 have been implicated in susceptibility to post-traumatic stress disorder (PTSD) and other stress-related disorders. We examined the relationship between mushroom, stubby, thin and filopodial spine densities measured with Golgi staining and FKBP5 gene expression in the medial orbitofrontal cortex (BA11) in individuals diagnosed with PTSD and normal controls (n = 8/8). ANCOVA revealed PTSD cases had a significantly elevated density of stubby spines (29%, P < 0.037) and a trend for a reduction in mushroom spine density (25%, p < 0.082). Levels of FKBP5 mRNA were marginally elevated in the PTSD cases (z = 1.94, p = 0.053) and levels correlated inversely with mushroom (Spearman's rho = −0.83, p < 0.001) and overall spine density (rho = −0.75, p < 0.002) and directly with stubby spine density (rho = 0.55, p < 0.027). These data suggest that FKBP5 may participate in a cellular pathway modulating neuronal spine density changes in the brain, and that this pathway may be dysregulated in PTSD.

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The present study is one of the first human post-mortem PTSD studies to date.

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Extreme stress has robust repercussions on glucocorticoids and dendritic spine morphology in animal models.

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FKBP5, involved in glucocorticoid signaling, was inversely associated with mushroom spine density in frontal cortex.

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These findings are consistent with alterations in glucocorticoid signaling in PTSD affecting synaptic plasticity.

Resting-state regional cerebral blood flow during adolescence: associations with initiation of substance use and prediction of future use disorders

BACKGROUND

Adolescence is a period of developmental flux when brain systems are vulnerable to influences of early substance use, which in turn relays increased risk for substance use disorders. Our study intent was to assess adolescent regional cerebral blood flow (rCBF) as it relates to current and future alcohol use. The aim was to identify brain-based predictors for initiation of alcohol use and onset of future substance use disorders.

METHODS

Quantitative rCBF was assessed in 100 adolescents (age 12-15). Prospective behavioral assessments were conducted annually over a three-year follow-up period to characterize onset of alcohol initiation, future drinking patterns and use disorders. Comparisons amongst use groups (i.e., current-, future-, and non-alcohol using adolescents) identified rCBF associated with initiation of alcohol use. Regression by future drinking patterns identified rCBF predictive of heavier drinking. Survival analysis determined whether or not baseline rCBF predicted later development of use disorders.

RESULTS

Baseline rCBF was decreased to the parietal cortex and increased to mesolimbic regions in adolescents currently using alcohol as well as those who would use alcohol in the future. Higher baseline rCBF to the left fusiform gyrus and lower rCBF to the right inferior parietal cortex and left cerebellum was associated with future drinking patterns as well as predicted the onset of alcohol and substance use disorders in this cohort.

CONCLUSIONS

Variations in resting rCBF to regions within reward and default mode or control networks appear to represent trait markers of alcohol use initiation and are predictive of future development of use disorders.

Heritability of fractional anisotropy in human white matter: a comparison of Human Connectome Project and ENIGMA-DTI data

The degree to which genetic factors influence brain connectivity is beginning to be understood. Large-scale efforts are underway to map the profile of genetic effects in various brain regions. The NIH-funded Human Connectome Project (HCP) is providing data valuable for analyzing the degree of genetic influence underlying brain connectivity revealed by state-of-the-art neuroimaging methods. We calculated the heritability of the fractional anisotropy (FA) measure derived from diffusion tensor imaging (DTI) reconstruction in 481 HCP subjects (194/287 M/F) consisting of 57/60 pairs of mono- and dizygotic twins, and 246 siblings. FA measurements were derived using (Enhancing NeuroImaging Genetics through Meta-Analysis) ENIGMA DTI protocols and heritability estimates were calculated using the SOLAR-Eclipse imaging genetic analysis package. We compared heritability estimates derived from HCP data to those publicly available through the ENIGMA-DTI consortium, which were pooled together from five-family based studies across the US, Europe, and Australia. FA measurements from the HCP cohort for eleven major white matter tracts were highly heritable (h(2)=0.53-0.90, p<10(-5)), and were significantly correlated with the joint-analytical estimates from the ENIGMA cohort on the tract and voxel-wise levels. The similarity in regional heritability suggests that the additive genetic contribution to white matter microstructure is consistent across populations and imaging acquisition parameters. It also suggests that the overarching genetic influence provides an opportunity to define a common genetic search space for future gene-discovery studies. Uniquely, the measurements of additive genetic contribution performed in this study can be repeated using online genetic analysis tools provided by the HCP ConnectomeDB web application.

Developmental change in amygdala reactivity during adolescence: effects of family history of depression and stressful life events

OBJECTIVE

Although heightened amygdala reactivity is observed in patients with major depression, two critical gaps in our knowledge remain. First, it is unclear whether heightened amygdala reactivity is a premorbid vulnerability or a consequence of the disorder. Second, it is unknown how and when this neural phenotype develops. The authors sought to address these gaps by evaluating developmental change in threat-related amygdala reactivity in adolescents at high or low risk for depression based on family history, before onset of disorder.

METHOD

At baseline and again 2 years later, adolescents (initially 11-15 years of age) participated in a functional MRI paradigm that elicited threat-related amygdala reactivity. After quality control, data were available for 232 adolescents at wave 1 and 197 adolescents at wave 2; longitudinal data meeting quality control at both waves were available for 157 of these participants. Change in amygdala reactivity was assessed as a function of family history of depression and severity of stressful life events.

RESULTS

Threat-related amygdala reactivity increased with age in participants with a positive family history regardless of the severity of life stress reported, and it increased in adolescents with a negative family history who reported relatively severe life stress. These changes in amygdala reactivity with age occurred in the absence of clinical disorder or increases in depressive symptoms.

CONCLUSIONS

These results suggest that heightened amygdala reactivity emerges during adolescence, prior to the development of depression, as a function of familial risk or, in the absence of familial risk, stressful life events.

Beyond genotype: serotonin transporter epigenetic modification predicts human brain function

We examined epigenetic regulation in regards to behaviorally and clinically relevant human brain function. Specifically, we found that increased promoter methylation of the serotonin transporter gene predicted increased threat-related amygdala reactivity and decreased mRNA expression in postmortem amygdala tissue. These patterns were independent of functional genetic variation in the same region. Furthermore, the association with amygdala reactivity was replicated in a second cohort and was robust to both sampling methods and age.

Multi-site study of additive genetic effects on fractional anisotropy of cerebral white matter: Comparing meta and megaanalytical approaches for data pooling

Combining datasets across independent studies can boost statistical power by increasing the numbers of observations and can achieve more accurate estimates of effect sizes. This is especially important for genetic studies where a large number of observations are required to obtain sufficient power to detect and replicate genetic effects. There is a need to develop and evaluate methods for joint-analytical analyses of rich datasets collected in imaging genetics studies. The ENIGMA-DTI consortium is developing and evaluating approaches for obtaining pooled estimates of heritability through meta-and mega-genetic analytical approaches, to estimate the general additive genetic contributions to the intersubject variance in fractional anisotropy (FA) measured from diffusion tensor imaging (DTI). We used the ENIGMA-DTI data harmonization protocol for uniform processing of DTI data from multiple sites. We evaluated this protocol in five family-based cohorts providing data from a total of 2248 children and adults (ages: 9-85) collected with various imaging protocols. We used the imaging genetics analysis tool, SOLAR-Eclipse, to combine twin and family data from Dutch, Australian and Mexican-American cohorts into one large "mega-family". We showed that heritability estimates may vary from one cohort to another. We used two meta-analytical (the sample-size and standard-error weighted) approaches and a mega-genetic analysis to calculate heritability estimates across-population. We performed leave-one-out analysis of the joint estimates of heritability, removing a different cohort each time to understand the estimate variability. Overall, meta- and mega-genetic analyses of heritability produced robust estimates of heritability.

Reduced reward anticipation in youth at high-risk for unipolar depression: a preliminary study

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Depression is characterized by reduced neural response to reward, particularly in the ventral striatum.

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Few studies have examined if alterations in reward functioning are present before the onset of depression.

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Youth at high- and low-familial risk for depression completed a reward task during a fMRI scan.

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High-risk youth had significantly less ventral striatal reactivity than low-risk youth during reward anticipation.

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Reward functioning is altered in individuals at high-familial risk for depression before the onset of the disorder.

Offspring of depressed parents are at risk for depression and recent evidence suggests that reduced positive affect (PA) may be a marker of risk. We investigated whether self-reports of PA and fMRI-measured striatal response to reward, a neural correlate of PA, are reduced in adolescent youth at high familial risk for depression (HR) relative to youth at low familial risk for depression (LR). Functional magnetic resonance imaging assessments were conducted with 14 HR and 12 LR youth. All youth completed an ecological momentary assessment protocol to measure PA in natural settings and a self-report measure of depression symptomatology. Analyses found that HR youth demonstrated lower striatal response than LR youth during both reward anticipation and outcome. However, after controlling for youth self-reports of depression, HR youth demonstrated lower striatal response than LR youth only during reward anticipation. No significant differences were found between HR and LR youth on subjective ratings of PA or depressive symptoms. Results are consistent with previous findings that reduced reward response is a marker of risk for depression, particularly during reward anticipation, even in the absence of (or accounting for) disrupted subjective mood. Further examinations of prospective associations between reward response and depression onset are needed.

FKBP5 and emotional neglect interact to predict individual differences in amygdala reactivity

Individual variation in physiological responsiveness to stress mediates risk for mental illness and is influenced by both experiential and genetic factors. Common polymorphisms in the human gene for FK506 binding protein 5 (FKBP5), which is involved in transcriptional regulation of the hypothalamic-pituitary-adrenal (HPA) axis, have been shown to interact with childhood abuse and trauma to predict stress-related psychopathology. In the current study, we examined if such gene-environment interaction effects may be related to variability in the threat-related reactivity of the amygdala, which plays a critical role in mediating physiological and behavioral adaptations to stress including modulation of the HPA axis. To this end, 139 healthy Caucasian youth completed a blood oxygen level-dependent functional magnetic resonance imaging probe of amygdala reactivity and self-report assessments of emotional neglect (EN) and other forms of maltreatment. These individuals were genotyped for 6 FKBP5 polymorphisms (rs7748266, rs1360780, rs9296158, rs3800373, rs9470080 and rs9394309) previously associated with psychopathology and/or HPA axis function. Interactions between each SNP and EN emerged such that risk alleles predicted relatively increased dorsal amygdala reactivity in the context of higher EN, even after correcting for multiple testing. Two different haplotype analyses confirmed this relationship as haplotypes with risk alleles also exhibited increased amygdala reactivity in the context of higher EN. Our results suggest that increased threat-related amygdala reactivity may represent a mechanism linking psychopathology to interactions between common genetic variants affecting HPA axis function and childhood trauma.

A coordinate-based meta-analytic model of trauma processing in posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) has a well-defined set of symptoms that can be elicited during traumatic imagery tasks. For this reason, trauma imagery tasks are often employed in functional neuroimaging studies. Here, coordinate-based meta-analysis (CBM) was used to pool eight studies applying traumatic imagery tasks to identify sites of task-induced activation in 170 PTSD patients and 104 healthy controls. In this way, right anterior cingulate (ACC), right posterior cingulate (PCC), and left precuneus (Pcun) were identified as regions uniquely active in PTSD patients relative to healthy controls. To further characterize these regions, their normal interactions, and their typical functional roles, meta-analytic connectivity modeling (MACM) with behavioral filtering was applied. MACM indicated that the PCC and Pcun regions were frequently co-active and associated with processing of cognitive information, particularly in explicit memory tasks. Emotional processing was particularly associated with co-activity of the ACC and PCC, as mediated by the thalamus. By narrowing the regions of interest to those commonly active across multiple studies (using CBM) and developing a priori hypotheses about directed probabilistic dependencies amongst these regions, this proposed model-when applied in the context of graphical and causal modeling-should improve model fit and thereby increase statistical power for detecting differences between subject groups and between treatments in neuroimaging studies of PTSD.

Mineralocorticoid receptor Iso/Val (rs5522) genotype moderates the association between previous childhood emotional neglect and amygdala reactivity

OBJECTIVE

The amygdala is especially reactive to threatening stimuli, and the degree of reactivity predicts individual differences in the expression of depression and anxiety. Emerging research suggests that emotional neglect during childhood as well as hypercortisolemia may lead to heightened threat-related amygdala reactivity. This raises the possibility that genetic variation affecting hypothalamic-pituitary-adrenal (HPA) axis function contributes to individual differences in amygdala reactivity, both independently and as a function of childhood emotional neglect.

METHOD

This study assessed whether the mineralocorticoid receptor iso/val polymorphism (rs5522), a functional genetic variant affecting HPA axis function, influenced threat-related amygdala reactivity in 279 individuals in late childhood and early adolescence. The study also explored the extent to which any effects of the genotype on amygdala reactivity were contingent upon previous childhood emotional neglect.

RESULTS

Prior childhood emotional neglect and the val allele were associated with greater amygdala reactivity. Moreover, a significant genotype-by-emotional neglect interaction was observed whereby greater amygdala reactivity in val allele carriers was independent of previous childhood emotional neglect, while greater reactivity in iso homozygotes was revealed only in the context of a history of elevated emotional neglect. At relatively low levels of previous emotional neglect, val carriers had heightened amygdala reactivity relative to iso homozygotes.

CONCLUSIONS

These results suggest that relatively greater amygdala reactivity may represent a biological mechanism through which childhood adversity and functional genetic variation in HPA axis responsiveness to stress may mediate risk for psychopathology.

Sex differences in cortisol response to corticotropin releasing hormone challenge over puberty: Pittsburgh Pediatric Neurobehavioral Studies

OBJECTIVE

Consistent sex differences in regulation of the hypothalamic pituitary adrenocortical (HPA) axis have been shown in animal models and emerge over puberty. However, parallel work in humans is lacking despite implications for elucidating the emergence of sex differences in depression over puberty. We investigated sex differences in HPA response to corticotropin releasing hormone (CRH) challenge over puberty in a carefully screened normative sample.

METHODS

Participants were 68 healthy children (41% girls), ages 6-16, with no personal or family history of psychiatric disorder. Pubertal maturation was determined by Tanner staging. Following 24h of adaptation, 9-10 plasma cortisol samples were collected over 30-40 min pre-infusion baseline, 1 μg/kg CRH infusion, and 90-180 min post-infusion recovery. Thirty-seven participants completed 2+ CRH challenges allowing inclusion of cross-sectional and longitudinal data in all analyses. The influence of gender and pubertal maturation on parameters of cortisol response to CRH challenge was investigated using nonlinear mixed model methodology.

RESULTS

Girls showed increasing total cortisol output following CRH challenge over puberty, while boys showed little change in total cortisol output over puberty. Increased cortisol output in girls was explained by slower reactivity and recovery rates leading to prolonged time to reach peak cortisol and delayed return to baseline over puberty. Girls also showed increasing baseline cortisol over puberty, while boys showed declining baseline over puberty.

CONCLUSION

Results reveal subtle normative sex differences in the influence of pubertal maturation on HPA regulation at the pituitary level. This normative shift may tip the balance towards stress response dysregulation in girls at high risk for depression, and may represent one potential mechanism underlying elevated rates of depression among pubescent girls.

Common genetic influences on depression, alcohol, and substance use disorders in Mexican-American families

Multiple genetic and environmental factors influence the risk for both major depression and alcohol/substance use disorders. In addition, there is evidence that these illnesses share genetic factors. Although, the heritability of these illnesses is well established, relatively few studies have focused on ethnic minority populations. Here, we document the prevalence, heritability, and genetic correlations between major depression and alcohol and drug disorders in a large, community-ascertained sample of Mexican-American families. A total of 1,122 Mexican-American individuals from 71 extended pedigrees participated in the study. All subjects received in-person psychiatric interviews. Heritability, genetic, and environmental correlations were estimated using SOLAR. Thirty-five percent of the sample met criteria for DSM-IV lifetime major depression, 34% met lifetime criteria for alcohol use disorders, and 8% met criteria for lifetime drug use disorders. The heritability for major depression was estimated to be h(2) = 0.393 (P = 3.7 × 10(-6)). Heritability estimates were higher for recurrent depression (h(2) = 0.463, P = 4.0 × 10(-6)) and early onset depression (h(2) = 0.485, P = 8.5 × 10(-5)). While the genetic correlation between major depression and alcohol use disorders was significant (ρ(g) = 0.58, P = 7 × 10(-3)), the environmental correlation between these traits was not significant. Although, there is evidence for increased rates of depression and substance use in US-born individuals of Mexican ancestry, our findings indicate that genetic control over major depression and alcohol/substance use disorders in the Mexican-American population is similar to that reported in other populations.

Fractional anisotropy of cerebral white matter and thickness of cortical gray matter across the lifespan

We examined age trajectories of fractional anisotropy (FA) of cerebral white matter (WM) and thickness of cortical gray matter (GM) in 1031 healthy human subjects (aged 11-90 years). Whole-brain FA and GM thickness values followed quadratic trajectories with age but the relationship between them was linear, indicating that a putative biological mechanism may explain the non-linearity of their age trajectories. Inclusion of the FA values into the quadratic model of the whole-brain and regional GM thickness changes with age made the effect of the age(2) term no longer significant for the whole-brain GM thickness and greatly reduced its significance for regional GM thickness measurements. The phylogenetic order of cerebral myelination helped to further explain the intersubject variability in GM thickness. FA values for the early maturing WM were significantly better (p=10(-6)) at explaining variability in GM thickness in maturing (aged 11-20) subjects than FA values for the late maturing WM. The opposite trend was observed for aging subjects (aged 40-90) where FA values for the late maturing WM were better (p=10(-16)) at explaining the variability in GM thickness. We concluded that the non-linearity of the age trajectory for GM thickness, measured from T1-weighted MRI, was partially explained by the heterogeneity and the heterochronicity of the age-related changes in the microintegrity of cerebral WM. We consider these findings as the evidence that the measurements of age-related changes in GM thickness and FA are driven, in part, by a common biological mechanism, presumed to be related to changes in cerebral myelination.