Publications by authors named "Dewleen G Baker"

125 Publications

A cohort study of neuropsychological functioning in spouses of U.S. Gulf War veterans.

Life Sci 2021 Nov 25;284:119894. Epub 2021 Aug 25.

School of Medicine, Washington University, St. Louis, MO, USA.

Aims: Veterans of the 1991 Gulf War reported symptoms in their spouses that mirrored veterans' symptoms following their return from the war, including problems with attention and memory. Neuropsychological functioning in these spouses has not been examined with objective tests. This study sought to determine if these spouses exhibited deficits in neuropsychological functioning.

Main Methods: Spouses of a national cohort of 1991 Gulf War deployed (n = 470) and non-deployed veterans (n = 524) were examined with neuropsychological tests in 1999-2001.

Key Findings: Neuropsychological tests were factor analyzed yielding five factors: verbal memory, visual memory, attention/working memory, visual organization, and motor speed. Spouses of deployed and nondeployed veterans did not differ on mean factor scores, percentage of impaired factors, or individual test scores. Spouse attention/working memory was related to their having diagnoses of PTSD or anxiety disorders, or self-reported symptoms of current anxiety. Spouse visual memory was related to a diagnosis of current depression. Spouse motor speed was related to their own status of having chronic multisymptom illness (CMI).

Significance: Spouses of Gulf War deployed and nondeployed veterans demonstrated similar neuropsychological functioning, although spouses with psychiatric diagnoses and symptoms, or CMI demonstrated neuropsychological impairments characteristic of those conditions, suggesting that monitoring spouses for these conditions and impairments may be warranted. This pattern of relative weaknesses mirrors some of the previously reported findings for Gulf War veterans, although the veterans displayed neuropsychological impairments beyond what was accounted for by these conditions.
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http://dx.doi.org/10.1016/j.lfs.2021.119894DOI Listing
November 2021

Dissociable impact of childhood trauma and deployment trauma on affective modulation of startle.

Neurobiol Stress 2021 Nov 26;15:100362. Epub 2021 Jun 26.

VA Center of Excellence for Stress and Mental Health (CESAMH), USA.

Trauma disorders are often associated with alterations in aversive anticipation and disruptions in emotion/fear circuits. Heightened or blunted anticipatory responding to negative cues in adulthood may be due to differential trauma exposure during development, and previous trauma exposure in childhood may also modify effects of subsequent trauma in adulthood. The aim of the current investigation was to examine the contributions of childhood trauma on affective modulation of startle before and after trauma exposure in adulthood (a combat deployment). Adult male participants from the Marine Resilience Study with (n = 1145) and without (n = 1312) a history of reported childhood trauma completed an affective modulation of startle task to assess aversive anticipation. Affective startle response was operationalized by electromyography (EMG) recording of the orbicularis oculi muscle in response to acoustic stimuli when anticipating positive and negative affective images. Startle responses to affective images were also assessed. Testing occurred over three time-points; before going on a 7 month combat deployment and 3 and 6 months after returning from deployment. Startle response when anticipating negative images was greater compared to pleasant images across all three test periods. Across all 3 time points, childhood trauma was consistently associated with significantly blunted startle when anticipating negative images, suggesting reliable effects of childhood trauma on aversive anticipation. Conversely, deployment trauma was associated with increased startle reactivity post-deployment compared to pre-deployment, which was independent of childhood trauma and image valence. These results support the hypothesis that trauma exposure during development vs. adulthood may have dissociable effects on aversive anticipation and arousal mechanisms. Further study in women and across more refined age groups is needed to test generalizability and identify potential developmental windows for these differential effects.
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http://dx.doi.org/10.1016/j.ynstr.2021.100362DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8259305PMC
November 2021

Examining Individual and Synergistic Contributions of PTSD and Genetics to Blood Pressure: A Trans-Ethnic Meta-Analysis.

Front Neurosci 2021 23;15:678503. Epub 2021 Jun 23.

Department of Psychiatry, Case Western Reserve University, Cleveland, OH, United States.

Growing research suggests that posttraumatic stress disorder (PTSD) may be a risk factor for poor cardiovascular health, and yet our understanding of who might be at greatest risk of adverse cardiovascular outcomes after trauma is limited. In this study, we conducted the first examination of the individual and synergistic contributions of PTSD symptoms and blood pressure genetics to continuous blood pressure levels. We harnessed the power of the Psychiatric Genomics Consortium-PTSD Physical Health Working Group and investigated these associations across 11 studies of 72,224 trauma-exposed individuals of European ( = 70,870) and African ( = 1,354) ancestry. Genetic contributions to blood pressure were modeled via polygenic scores (PGS) for systolic blood pressure (SBP) and diastolic blood pressure (DBP) that were derived from a prior trans-ethnic blood pressure genome-wide association study (GWAS). Results of trans-ethnic meta-analyses revealed significant main effects of the PGS on blood pressure levels [SBP: β = 2.83, standard error (SE) = 0.06, < 1E-20; DBP: β = 1.32, SE = 0.04, < 1E-20]. Significant main effects of PTSD symptoms were also detected for SBP and DBP in trans-ethnic meta-analyses, though there was significant heterogeneity in these results. When including data from the largest contributing study - United Kingdom Biobank - PTSD symptoms were negatively associated with SBP levels (β = -1.46, SE = 0.44, = 9.8E-4) and positively associated with DBP levels (β = 0.70, SE = 0.26, = 8.1E-3). However, when excluding the United Kingdom Biobank cohort in trans-ethnic meta-analyses, there was a nominally significant positive association between PTSD symptoms and SBP levels (β = 2.81, SE = 1.13, = 0.01); no significant association was observed for DBP (β = 0.43, SE = 0.78, = 0.58). Blood pressure PGS did not significantly moderate the associations between PTSD symptoms and blood pressure levels in meta-analyses. Additional research is needed to better understand the extent to which PTSD is associated with high blood pressure and how genetic as well as contextual factors may play a role in influencing cardiovascular risk.
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http://dx.doi.org/10.3389/fnins.2021.678503DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8262489PMC
June 2021

A randomized trial of safety and pharmacodynamic interactions between a selective glucocorticoid receptor antagonist, PT150, and ethanol in healthy volunteers.

Sci Rep 2021 05 10;11(1):9876. Epub 2021 May 10.

Menninger Department of Psychiatry, Baylor College of Medicine, Houston, USA.

PT150, a novel competitive glucocorticoid receptor (GR) antagonist, has proven safe in animal models, healthy volunteers, and people with depression. Our study is the first to investigate PT150's safety with alcohol use. The primary objective of this study was to evaluate pharmacodynamic interactions between ethanol and PT150 in healthy subjects. This single-site, Phase I pilot trial consisted of community-recruited, healthy, alcohol-experienced participants aged 21-64 years. Of 32 participants screened, 11 were enrolled and randomized, one of which withdrew before intervention. PT150 (900 mg/day) was administered orally to all participants for five days. All participants received two beverage challenges on Day 1 (before PT150 administration) and Day 5 (after PT150 administration). On challenge days, they received both alcohol (16% ethanol) and placebo (1% ethanol) beverages in random order. Primary outcomes included breath alcohol level, blood pressure, heart rate, adverse events, and electrocardiogram changes. There were no statistically significant differences in vital signs or estimated blood alcohol concentrations between PT150 non-exposed and exposed groups during the ethanol challenge. There were no clinically significant abnormal electrocardiograms or serious adverse events. These data show that administration of PT150 with concurrent alcohol use is safe and well-tolerated. This study supports a future pharmacokinetic interaction study between PT150 and alcohol.Trial Registration ClinicalTrials.gov Identifier: NCT03548714.
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http://dx.doi.org/10.1038/s41598-021-88609-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8111026PMC
May 2021

Resting-state magnetoencephalography source magnitude imaging with deep-learning neural network for classification of symptomatic combat-related mild traumatic brain injury.

Hum Brain Mapp 2021 05 15;42(7):1987-2004. Epub 2021 Jan 15.

Radiology, Research, and Psychiatry Services, VA San Diego Healthcare System, San Diego, California, USA.

Combat-related mild traumatic brain injury (cmTBI) is a leading cause of sustained physical, cognitive, emotional, and behavioral disabilities in Veterans and active-duty military personnel. Accurate diagnosis of cmTBI is challenging since the symptom spectrum is broad and conventional neuroimaging techniques are insensitive to the underlying neuropathology. The present study developed a novel deep-learning neural network method, 3D-MEGNET, and applied it to resting-state magnetoencephalography (rs-MEG) source-magnitude imaging data from 59 symptomatic cmTBI individuals and 42 combat-deployed healthy controls (HCs). Analytic models of individual frequency bands and all bands together were tested. The All-frequency model, which combined delta-theta (1-7 Hz), alpha (8-12 Hz), beta (15-30 Hz), and gamma (30-80 Hz) frequency bands, outperformed models based on individual bands. The optimized 3D-MEGNET method distinguished cmTBI individuals from HCs with excellent sensitivity (99.9 ± 0.38%) and specificity (98.9 ± 1.54%). Receiver-operator-characteristic curve analysis showed that diagnostic accuracy was 0.99. The gamma and delta-theta band models outperformed alpha and beta band models. Among cmTBI individuals, but not controls, hyper delta-theta and gamma-band activity correlated with lower performance on neuropsychological tests, whereas hypo alpha and beta-band activity also correlated with lower neuropsychological test performance. This study provides an integrated framework for condensing large source-imaging variable sets into optimal combinations of regions and frequencies with high diagnostic accuracy and cognitive relevance in cmTBI. The all-frequency model offered more discriminative power than each frequency-band model alone. This approach offers an effective path for optimal characterization of behaviorally relevant neuroimaging features in neurological and psychiatric disorders.
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http://dx.doi.org/10.1002/hbm.25340DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8046098PMC
May 2021

Epigenome-wide meta-analysis of PTSD across 10 military and civilian cohorts identifies methylation changes in AHRR.

Nat Commun 2020 11 24;11(1):5965. Epub 2020 Nov 24.

Brown University, Psychiatry and Human Behavior, Department of Pediatric Research, Providence, RI, USA.

Epigenetic differences may help to distinguish between PTSD cases and trauma-exposed controls. Here, we describe the results of the largest DNA methylation meta-analysis of PTSD to date. Ten cohorts, military and civilian, contribute blood-derived DNA methylation data from 1,896 PTSD cases and trauma-exposed controls. Four CpG sites within the aryl-hydrocarbon receptor repressor (AHRR) associate with PTSD after adjustment for multiple comparisons, with lower DNA methylation in PTSD cases relative to controls. Although AHRR methylation is known to associate with smoking, the AHRR association with PTSD is most pronounced in non-smokers, suggesting the result was independent of smoking status. Evaluation of metabolomics data reveals that AHRR methylation associated with kynurenine levels, which are lower among subjects with PTSD. This study supports epigenetic differences in those with PTSD and suggests a role for decreased kynurenine as a contributor to immune dysregulation in PTSD.
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http://dx.doi.org/10.1038/s41467-020-19615-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7686485PMC
November 2020

Epigenome-wide meta-analysis of PTSD across 10 military and civilian cohorts identifies methylation changes in AHRR.

Nat Commun 2020 11 24;11(1):5965. Epub 2020 Nov 24.

Brown University, Psychiatry and Human Behavior, Department of Pediatric Research, Providence, RI, USA.

Epigenetic differences may help to distinguish between PTSD cases and trauma-exposed controls. Here, we describe the results of the largest DNA methylation meta-analysis of PTSD to date. Ten cohorts, military and civilian, contribute blood-derived DNA methylation data from 1,896 PTSD cases and trauma-exposed controls. Four CpG sites within the aryl-hydrocarbon receptor repressor (AHRR) associate with PTSD after adjustment for multiple comparisons, with lower DNA methylation in PTSD cases relative to controls. Although AHRR methylation is known to associate with smoking, the AHRR association with PTSD is most pronounced in non-smokers, suggesting the result was independent of smoking status. Evaluation of metabolomics data reveals that AHRR methylation associated with kynurenine levels, which are lower among subjects with PTSD. This study supports epigenetic differences in those with PTSD and suggests a role for decreased kynurenine as a contributor to immune dysregulation in PTSD.
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http://dx.doi.org/10.1038/s41467-020-19615-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7686485PMC
November 2020

Analysis of Genetically Regulated Gene Expression Identifies a Prefrontal PTSD Gene, SNRNP35, Specific to Military Cohorts.

Cell Rep 2020 06;31(9):107716

SAMRC Unit on Risk & Resilience in Mental Disorders, Department of Psychiatry, University of Cape Town, Cape Town 7700, South Africa.

To reveal post-traumatic stress disorder (PTSD) genetic risk influences on tissue-specific gene expression, we use brain and non-brain transcriptomic imputation. We impute genetically regulated gene expression (GReX) in 29,539 PTSD cases and 166,145 controls from 70 ancestry-specific cohorts and identify 18 significant GReX-PTSD associations corresponding to specific tissue-gene pairs. The results suggest substantial genetic heterogeneity based on ancestry, cohort type (military versus civilian), and sex. Two study-wide significant PTSD associations are identified in European and military European cohorts; ZNF140 is predicted to be upregulated in whole blood, and SNRNP35 is predicted to be downregulated in dorsolateral prefrontal cortex, respectively. In peripheral leukocytes from 175 marines, the observed PTSD differential gene expression correlates with the predicted differences for these individuals, and deployment stress produces glucocorticoid-regulated expression changes that include downregulation of both ZNF140 and SNRNP35. SNRNP35 knockdown in cells validates its functional role in U12-intron splicing. Finally, exogenous glucocorticoids in mice downregulate prefrontal Snrnp35 expression.
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http://dx.doi.org/10.1016/j.celrep.2020.107716DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7359754PMC
June 2020

An epigenome-wide association study of posttraumatic stress disorder in US veterans implicates several new DNA methylation loci.

Clin Epigenetics 2020 03 14;12(1):46. Epub 2020 Mar 14.

Arq, Psychotrauma Reseach Expert Group, Diemen, NH, Netherlands.

Background: Previous studies using candidate gene and genome-wide approaches have identified epigenetic changes in DNA methylation (DNAm) associated with posttraumatic stress disorder (PTSD).

Methods: In this study, we performed an EWAS of PTSD in a cohort of Veterans (n = 378 lifetime PTSD cases and 135 controls) from the Translational Research Center for TBI and Stress Disorders (TRACTS) cohort assessed using the Illumina EPIC Methylation BeadChip which assesses DNAm at more than 850,000 sites throughout the genome. Our model included covariates for ancestry, cell heterogeneity, sex, age, and a smoking score based on DNAm at 39 smoking-associated CpGs. We also examined in EPIC-based DNAm data generated from pre-frontal cortex (PFC) tissue from the National PTSD Brain Bank (n = 72).

Results: The analysis of blood samples yielded one genome-wide significant association with PTSD at cg19534438 in the gene G0S2 (p = 1.19 × 10, p = 0.048). This association was replicated in an independent PGC-PTSD-EWAS consortium meta-analysis of military cohorts (p = 0.0024). We also observed association with the smoking-related locus cg05575921 in AHRR despite inclusion of a methylation-based smoking score covariate (p = 9.16 × 10), which replicates a previously observed PGC-PTSD-EWAS association (Smith et al. 2019), and yields evidence consistent with a smoking-independent effect. The top 100 EWAS loci were then examined in the PFC data. One of the blood-based PTSD loci, cg04130728 in CHST11, which was in the top 10 loci in blood, but which was not genome-wide significant, was significantly associated with PTSD in brain tissue (in blood p = 1.19 × 10, p = 0.60, in brain, p = 0.00032 with the same direction of effect). Gene set enrichment analysis of the top 500 EWAS loci yielded several significant overlapping GO terms involved in pathogen response, including "Response to lipopolysaccharide" (p = 6.97 × 10, p = 0.042).

Conclusions: The cross replication observed in independent cohorts is evidence that DNA methylation in peripheral tissue can yield consistent and replicable PTSD associations, and our results also suggest that that some PTSD associations observed in peripheral tissue may mirror associations in the brain.
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http://dx.doi.org/10.1186/s13148-020-0820-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7071645PMC
March 2020

Genomic influences on self-reported childhood maltreatment.

Transl Psychiatry 2020 01 27;10(1):38. Epub 2020 Jan 27.

US Army Medical Research and Materiel Command, Fort Detrick, MD, USA.

Childhood maltreatment is highly prevalent and serves as a risk factor for mental and physical disorders. Self-reported childhood maltreatment appears heritable, but the specific genetic influences on this phenotype are largely unknown. The aims of this study were to (1) identify genetic variation associated with self-reported childhood maltreatment, (2) estimate SNP-based heritability (h), (3) assess predictive value of polygenic risk scores (PRS) for childhood maltreatment, and (4) quantify genetic overlap of childhood maltreatment with mental and physical health-related phenotypes, and condition the top hits from our analyses when such overlap is present. Genome-wide association analysis for childhood maltreatment was undertaken, using a discovery sample from the UK Biobank (UKBB) (n = 124,000) and a replication sample from the Psychiatric Genomics Consortium-posttraumatic stress disorder group (PGC-PTSD) (n = 26,290). h for childhood maltreatment and genetic correlations with mental/physical health traits were calculated using linkage disequilibrium score regression. PRS was calculated using PRSice and mtCOJO was used to perform conditional analysis. Two genome-wide significant loci associated with childhood maltreatment (rs142346759, p = 4.35 × 10, FOXP1; rs10262462, p = 3.24 × 10, FOXP2) were identified in the discovery dataset but were not replicated in PGC-PTSD. h for childhood maltreatment was ~6% and the PRS derived from the UKBB was significantly predictive of childhood maltreatment in PGC-PTSD (r = 0.0025; p = 1.8 × 10). The most significant genetic correlation of childhood maltreatment was with depressive symptoms (r = 0.70, p = 4.65 × 10), although we show evidence that our top hits may be specific to childhood maltreatment. This is the first large-scale genetic study to identify specific variants associated with self-reported childhood maltreatment. Speculatively, FOXP genes might influence externalizing traits and so be relevant to childhood maltreatment. Alternatively, these variants may be associated with a greater likelihood of reporting maltreatment. A clearer understanding of the genetic relationships of childhood maltreatment, including particular abuse subtypes, with a range of phenotypes, may ultimately be useful in in developing targeted treatment and prevention strategies.
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http://dx.doi.org/10.1038/s41398-020-0706-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7026037PMC
January 2020

Author Correction: A new common functional coding variant at the DDC gene change renal enzyme activity and modify renal dopamine function.

Sci Rep 2020 Feb 14;10(1):2996. Epub 2020 Feb 14.

Departments of Medicine, Pharmacology, Psychiatry, and Institute for Genomic Medicine, University of California at San Diego, La Jolla, CA, USA.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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http://dx.doi.org/10.1038/s41598-020-59785-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7021692PMC
February 2020

Longitudinal epigenome-wide association studies of three male military cohorts reveal multiple CpG sites associated with post-traumatic stress disorder.

Clin Epigenetics 2020 01 13;12(1):11. Epub 2020 Jan 13.

Department of Psychiatry and Neuropsychology, School for Mental health and Neuroscience, Maastricht University, Maastricht, Limburg, Netherlands.

Background: Epigenetic mechanisms have been suggested to play a role in the development of post-traumatic stress disorder (PTSD). Here, blood-derived DNA methylation data (HumanMethylation450 BeadChip) collected prior to and following combat exposure in three cohorts of male military members were analyzed to assess whether DNA methylation profiles are associated with the development of PTSD. A total of 123 PTSD cases and 143 trauma-exposed controls were included in the analyses. The Psychiatric Genomics Consortium (PGC) PTSD EWAS QC pipeline was used on all cohorts, and results were combined using a sample size weighted meta-analysis in a two-stage design. In stage one, we jointly analyzed data of two new cohorts (N = 126 and 78) for gene discovery, and sought to replicate significant findings in a third, previously published cohort (N = 62) to assess the robustness of our results. In stage 2, we aimed at maximizing power for gene discovery by combining all three cohorts in a meta-analysis.

Results: Stage 1 analyses identified four CpG sites in which, conditional on pre-deployment DNA methylation, post-deployment DNA methylation was significantly associated with PTSD status after epigenome-wide adjustment for multiple comparisons. The most significant (intergenic) CpG cg05656210 (p = 1.0 × 10) was located on 5q31 and significantly replicated in the third cohort. In addition, 19 differentially methylated regions (DMRs) were identified, but failed replication. Stage 2 analyses identified three epigenome-wide significant CpGs, the intergenic CpG cg05656210 and two additional CpGs located in MAD1L1 (cg12169700) and HEXDC (cg20756026). Interestingly, cg12169700 had an underlying single nucleotide polymorphism (SNP) which was located within the same LD block as a recently identified PTSD-associated SNP in MAD1L1. Stage 2 analyses further identified 12 significant differential methylated regions (DMRs), 1 of which was located in MAD1L1 and 4 were situated in the human leukocyte antigen (HLA) region.

Conclusions: This study suggests that the development of combat-related PTSD is associated with distinct methylation patterns in several genomic positions and regions. Our most prominent findings suggest the involvement of the immune system through the HLA region and HEXDC, and MAD1L1 which was previously associated with PTSD.
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http://dx.doi.org/10.1186/s13148-019-0798-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6958602PMC
January 2020

Sleep disturbance at pre-deployment is a significant predictor of post-deployment re-experiencing symptoms.

Eur J Psychotraumatol 2019 29;10(1):1679964. Epub 2019 Oct 29.

Center for Excellence in Stress and Mental Health, VA San Diego Healthcare System, San Diego, CA, USA.

: Insomnia is common in service members and associated with many mental and physical health problems. Recently, longitudinal data have been used to assess the impact of disturbed sleep on mental health outcomes. These studies have consistently shown relationships between sleep disturbance and development of mental illness. : The present study examined the longitudinal relationship between sleep disturbance and PTSD symptomatology in a cohort of Marines and Navy Corpsmen deployed to Iraq and Afghanistan (n = 2,404) assessed prior to deployment, as well as at -3 and 6 months post-deployment. Additionally, we aimed to investigate the extent to which these relationships are moderated by combat-stress severity, and to what extent these findings are replicated in a second, separate cohort of Marines and Navy corpsmen (n = 938) assessed with identical measures prior to deployment and within 3 months of return. : The present study employed latent variable path models to examine the relationships between pre-deployment sleep disturbance and post-deployment re-experiencing symptoms. Initial cross-lagged path models were conducted on discovery and replication samples to validate the hypothesized predictive relationships. Follow up moderation path models were then conducted to include the effect of combat-stress severity on these relationships. : Initial cross-lagged models supported a significant relationship between pre-deployment sleep disturbance and future re-experiencing PTSD symptoms at all time points. Initial moderation models showed a small moderator effect of combat-stress severity, though the main predictive relationship between pre-deployment sleep disturbance and PTSD symptoms remained significant. The moderator effect was not significant in the replication sample. : The results of this study support pre-deployment sleep disturbance as a risk factor for development of post-deployment PTSD symptoms. Interventions aimed at normalizing sleep may be important in preventive measures for PTSD.
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http://dx.doi.org/10.1080/20008198.2019.1679964DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6830277PMC
October 2019

Assessing Neuronal and Astrocyte Derived Exosomes From Individuals With Mild Traumatic Brain Injury for Markers of Neurodegeneration and Cytotoxic Activity.

Front Neurosci 2019 2;13:1005. Epub 2019 Oct 2.

Department of Neurosciences, University of California, San Diego, La Jolla, CA, United States.

Mild traumatic brain injury (mTBI) disproportionately affects military service members and is very difficult to diagnose. To-date, there is currently no blood-based, diagnostic biomarker for mTBI cases with persistent post concussive symptoms. To examine the potential of neuronally-derived (NDE) and astrocytic-derived (ADE) exosome cargo proteins as biomarkers of chronic mTBI in younger adults, we examined plasma exosomes from a prospective longitudinal study of combat-related risk and resilience, marine resiliency study II (MRSII). After return from a combat-deployment participants were interviewed to assess TBI exposure while on deployment. Plasma exosomes from military service members with mTBI (mean age, 21.7 years, = 19, avg. days since injury 151), and age-matched, controls (deployed service members who did not endorse a deployment-related TBI or a pre-deployment history of TBI; mean age, 21.95 years, = 20) were precipitated and enriched against a neuronal adhesion protein, L1-CAM, and an astrocyte marker, glutamine aspartate transporter (GLAST) using magnetic beads to immunocapture the proteins and subsequently selected by fluorescent activated cell sorting (FACS). Extracted protein cargo from NDE and ADE preparations were quantified for protein levels implicated in TBI neuropathology by standard ELISAs and on the ultra-sensitive single molecule assay (Simoa) platform. Plasma NDE and ADE levels of Aβ42 were significantly higher while plasma NDE and ADE levels of the postsynaptic protein, neurogranin (NRGN) were significantly lower in participants endorsing mTBI exposure compared to controls with no TBI history. Plasma NDE and ADE levels of Aβ40, total tau, and neurofilament light (NFL), P-T181-tau, P-S396-tau were either undetectable or not significantly different between the two groups. In an effort to understand the pathogenetic potential of NDE and ADE cargo proteins, neuron-like cultures were treated with NDE and ADE preparations from TBI and non-TBI groups. Lastly, we determined that plasma NDE but not ADE cargo proteins from mTBI samples were found to be toxic to neuron-like recipient cells . These data support the presence of markers of neurodegeneration in NDEs of mTBI and suggest that these NDEs can be used as tools to identify pathogenic mechanisms of TBI.
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http://dx.doi.org/10.3389/fnins.2019.01005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6797846PMC
October 2019

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

Nat Commun 2019 10 8;10(1):4558. Epub 2019 Oct 8.

Durham VA Medical Center, Research, Durham, NC, USA.

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.
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http://dx.doi.org/10.1038/s41467-019-12576-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6783435PMC
October 2019

Spinal cord stimulation in chronic pain: evidence and theory for mechanisms of action.

Bioelectron Med 2019 Jun;5

Department of Anesthesiology, Center for Pain Medicine, University of California San Diego School of Medicine, La Jolla, CA, USA.

Well-established in the field of bioelectronic medicine, Spinal Cord Stimulation (SCS) offers an implantable, non-pharmacologic treatment for patients with intractable chronic pain conditions. Chronic pain is a widely heterogenous syndrome with regard to both pathophysiology and the resultant phenotype. Despite advances in our understanding of SCS-mediated antinociception, there still exists limited evidence clarifying the pathways recruited when patterned electric pulses are applied to the epidural space. The rapid clinical implementation of novel SCS methods including burst, high frequency and dorsal root ganglion SCS has provided the clinician with multiple options to treat refractory chronic pain. While compelling evidence for safety and efficacy exists in support of these novel paradigms, our understanding of their mechanisms of action (MOA) dramatically lags behind clinical data. In this review, we reconstruct the available basic science and clinical literature that offers support for mechanisms of both paresthesia spinal cord stimulation (P-SCS) and paresthesia-free spinal cord stimulation (PF-SCS). While P-SCS has been heavily examined since its inception, PF-SCS paradigms have recently been clinically approved with the support of limited preclinical research. Thus, wide knowledge gaps exist between their clinical efficacy and MOA. To close this gap, many rich investigative avenues for both P-SCS and PF-SCS are underway, which will further open the door for paradigm optimization, adjunctive therapies and new indications for SCS. As our understanding of these mechanisms evolves, clinicians will be empowered with the possibility of improving patient care using SCS to selectively target specific pathophysiological processes in chronic pain.
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http://dx.doi.org/10.1186/s42234-019-0023-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6703564PMC
June 2019

Marked Increases in Resting-State MEG Gamma-Band Activity in Combat-Related Mild Traumatic Brain Injury.

Cereb Cortex 2020 01;30(1):283-295

Radiology, Research, and Psychiatry Services, VA San Diego Healthcare System, San Diego, CA, USA.

Combat-related mild traumatic brain injury (mTBI) is a leading cause of sustained impairments in military service members and veterans. Recent animal studies show that GABA-ergic parvalbumin-positive interneurons are susceptible to brain injury, with damage causing abnormal increases in spontaneous gamma-band (30-80 Hz) activity. We investigated spontaneous gamma activity in individuals with mTBI using high-resolution resting-state magnetoencephalography source imaging. Participants included 25 symptomatic individuals with chronic combat-related blast mTBI and 35 healthy controls with similar combat experiences. Compared with controls, gamma activity was markedly elevated in mTBI participants throughout frontal, parietal, temporal, and occipital cortices, whereas gamma activity was reduced in ventromedial prefrontal cortex. Across groups, greater gamma activity correlated with poorer performances on tests of executive functioning and visuospatial processing. Many neurocognitive associations, however, were partly driven by the higher incidence of mTBI participants with both higher gamma activity and poorer cognition, suggesting that expansive upregulation of gamma has negative repercussions for cognition particularly in mTBI. This is the first human study to demonstrate abnormal resting-state gamma activity in mTBI. These novel findings suggest the possibility that abnormal gamma activities may be a proxy for GABA-ergic interneuron dysfunction and a promising neuroimaging marker of insidious mild head injuries.
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http://dx.doi.org/10.1093/cercor/bhz087DOI Listing
January 2020

Brain Amygdala Volume Increases in Veterans and Active-Duty Military Personnel With Combat-Related Posttraumatic Stress Disorder and Mild Traumatic Brain Injury.

J Head Trauma Rehabil 2020 Jan/Feb;35(1):E1-E9

Department of Physical Medicine and Rehabilitation University of Michigan, Ann Arbor, Michigan (Dr Pieper), Departments of Orthopaedic Surgery (Dr Chang), Radiology, Research, and Psychiatry Services (Mss Swan and Quinto and Drs Lee, Baker, and M. Huang), Radiology (Mss Swan and Quinto and Drs Lee and M. Huang), Neurosciences (Dr Nichols), and Psychiatry (Dr Baker), University of California, San Diego; College of Medicine, King Saud University, Riyadh, Saudi Arabia (Ms Mahasin); Department of Radiology and Biomedical Imaging, University of California, San Francisco (Dr Diwakar); Department of Bioengineering, Stanford University, Stanford, California (Mr C. Huang); Department of Management Information Systems, San Diego State University, San Diego, California (Mr Swan); and VA Center of Excellence for Stress and Mental Health, San Diego, California (Dr Baker).

Objective: To identify amygdalar volumetric differences associated with posttraumatic stress disorder (PTSD) in individuals with comorbid mild traumatic brain injury (mTBI) compared with those with mTBI-only and to examine the effects of intracranial volume (ICV) on amygdala volumetric measures.

Setting: Marine Corps Base and VA Healthcare System.

Participants: A cohort of veterans and active-duty military personnel with combat-related mTBI (N = 89).

Design: Twenty-nine participants were identified with comorbid PTSD and mTBI. The remaining 60 formed the mTBI-only control group. Structural images of brains were obtained with a 1.5-T MRI scanner using a T1-weighted 3D-IR-FSPGR pulse sequence. Automatic segmentation was performed in Freesurfer.

Main Measures: Amygdala volumes with/without normalizations to ICV.

Results: The comorbid mTBI/PTSD group had significantly larger amygdala volumes, when normalized to ICV, compared with the mTBI-only group. The right and left amygdala volumes after normalization to ICV were 0.122% ± 0.012% and 0.118% ± 0.011%, respectively, in the comorbid group compared with 0.115% ± 0.012% and 0.112% ± 0.009%, respectively, in the mTBI-only group (corrected P < .05).

Conclusions: The ICV normalization analysis performed here may resolve previous literature discrepancies. This is an intriguing structural finding, given the role of the amygdala in the challenging neuroemotive symptoms witnessed in casualties of combat-related mTBI and PTSD.
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http://dx.doi.org/10.1097/HTR.0000000000000492DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6814512PMC
July 2021

Mental health in spouses of U.S. Gulf War veterans.

Psychiatry Res 2019 05 27;275:287-295. Epub 2019 Mar 27.

School of Medicine, Washington University, St. Louis, MO, USA.

Veterans' spouses are at risk for mental distress and substance use. We examined long term psychological functioning in spouses from a national cohort of 1991 Gulf War era veterans. From clinical interviews, spouses of deployed veterans (n = 488) did not have a greater prevalence of post-war mental disorders compared to spouses of non-deployed veterans (n = 536); however, in couples that were living together since the war, there was an increased risk of anxiety disorders or any one disorder. On questionnaires, the impact varied but was most consistently observed in more severe depression and greater functional impairment in spouses of deployed compared to non-deployed veterans. If a veteran developed post-war anxious/depressive disorders or any one mental disorder, the matched spouse was more likely to develop post-war anxious/depressive disorders or any one mental disorder, respectively. Veteran combat exposure did not similarly increase the risk of spouse post-war mental disorders. Greater spouse self-reported symptomatology was observed in spouses of veterans with anxious/depressive disorders even when controlling for deployment. In summary, the war conferred greater risk for spouse mental disorders and distress for spouses of veterans with mental health disorders, with some increased risk for spouses of deployed veterans, especially in couples together since the war.
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http://dx.doi.org/10.1016/j.psychres.2019.03.043DOI Listing
May 2019

Developmental Trajectories of Early Life Stress and Trauma: A Narrative Review on Neurobiological Aspects Beyond Stress System Dysregulation.

Front Psychiatry 2019 11;10:118. Epub 2019 Mar 11.

Department of Psychiatry, University of California, San Diego, La Jolla, CA, United States.

Early life stressors display a high universal prevalence and constitute a major public health problem. Prolonged psychoneurobiological alterations as sequelae of early life stress (ELS) could represent a developmental risk factor and mediate risk for disease, leading to higher physical and mental morbidity rates in later life. ELS could exert a programming effect on sensitive neuronal brain networks related to the stress response during critical periods of development and thus lead to enduring hyper- or hypo-activation of the stress system and altered glucocorticoid signaling. In addition, alterations in emotional and autonomic reactivity, circadian rhythm disruption, functional and structural changes in the brain, as well as immune and metabolic dysregulation have been lately identified as important risk factors for a chronically impaired homeostatic balance after ELS. Furthermore, human genetic background and epigenetic modifications through stress-related gene expression could interact with these alterations and explain inter-individual variation in vulnerability or resilience to stress. This narrative review presents relevant evidence from mainly human research on the ten most acknowledged neurobiological allostatic pathways exerting enduring adverse effects of ELS even decades later (hypothalamic-pituitary-adrenal axis, autonomic nervous system, immune system and inflammation, oxidative stress, cardiovascular system, gut microbiome, sleep and circadian system, genetics, epigenetics, structural, and functional brain correlates). Although most findings back a causal relation between ELS and psychobiological maladjustment in later life, the precise developmental trajectories and their temporal coincidence has not been elucidated as yet. Future studies should prospectively investigate putative mediators and their temporal sequence, while considering the potentially delayed time-frame for their phenotypical expression. Better screening strategies for ELS are needed for a better individual prevention and treatment.
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http://dx.doi.org/10.3389/fpsyt.2019.00118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6421311PMC
March 2019

A new common functional coding variant at the DDC gene change renal enzyme activity and modify renal dopamine function.

Sci Rep 2019 03 25;9(1):5055. Epub 2019 Mar 25.

Departments of Medicine, Pharmacology, Psychiatry, and Institute for Genomic Medicine, University of California at San Diego, La Jolla, CA, USA.

The intra-renal dopamine (DA) system is highly expressed in the proximal tubule and contributes to Na+ and blood pressure homeostasis, as well as to the development of nephropathy. In the kidney, the enzyme DOPA Decarboxylase (DDC) originating from the circulation. We used a twin/family study design, followed by polymorphism association analysis at DDC locus to elucidate heritable influences on renal DA production. Dense single nucleotide polymorphism (SNP) genotyping across the DDC locus on chromosome 7p12 was analyzed by re-sequencing guided by trait-associated genetic markers to discover the responsible genetic variation. We also characterized kinetics of the expressed DDC mutant enzyme. Systematic polymorphism screening across the 15-Exon DDC locus revealed a single coding variant in Exon-14 that was associated with DA excretion and multiple other renal traits indicating pleiotropy. When expressed and characterized in eukaryotic cells, the 462Gln variant displayed lower Vmax (maximal rate of product formation by an enzyme) (21.3 versus 44.9 nmol/min/mg) and lower Km (substrate concentration at which half-maximal product formation is achieved by an enzyme.)(36.2 versus 46.8 μM) than the wild-type (Arg462) allele. The highly heritable DA excretion trait is substantially influenced by a previously uncharacterized common coding variant (Arg462Gln) at the DDC gene that affects multiple renal tubular and glomerular traits, and predicts accelerated functional decline in chronic kidney disease.
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http://dx.doi.org/10.1038/s41598-019-41504-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6433864PMC
March 2019

Direct and indirect relationships among posttraumatic stress disorder, depression, hostility, anger, and verbal and physical aggression in returning veterans.

Aggress Behav 2019 07 5;45(4):417-426. Epub 2019 Mar 5.

Veterans Affairs San Diego Healthcare System, San Diego, CA.

Hostility, anger, and aggression are conceptually related but unique constructs found to occur more often among veterans with posttraumatic stress disorder (PTSD) than among civilians or veterans without PTSD. However, the pathways between PTSD, depression, hostility, anger, and aggression have not been comprehensively characterized. Therefore, drawing on a sample of returning Operation Enduring Freedom/Operation Iraqi Freedom combat veterans ( N = 175; 95% male; mean age 30 years), this study sought to examine the direct and indirect relationships among PTSD, depression, hostility, anger, and four types of aggression: verbal, and physical toward self, others, and objects. Functional modeling of direct effects was done using multiple least-squares regression and bootstrapped mediation analyses were carried out to test indirect effects. Results indicate that PTSD is not the overall direct contributor to different forms of aggression, supporting the mediating role of depression and trait anger. Depression symptoms explain part of the relationships between PTSD and verbal aggression, physical aggression toward objects, and physical aggression toward self and trait anger explains part of the relationships between PTSD and verbal aggression, physical aggression toward objects, and physical aggression toward others. Our findings support the importance of assessing for anger, depression, and different types of aggression among veterans presenting for PTSD treatment to develop individualized treatment plans that may benefit from early incorporation of interventions.
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http://dx.doi.org/10.1002/ab.21827DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6814381PMC
July 2019

Noninvasive vagus nerve stimulation alters neural response and physiological autonomic tone to noxious thermal challenge.

PLoS One 2019 13;14(2):e0201212. Epub 2019 Feb 13.

VA Center of Excellence for Stress and Mental Health, VA San Diego Healthcare System, La Jolla, CA, United States of America.

The mechanisms by which noninvasive vagal nerve stimulation (nVNS) affect central and peripheral neural circuits that subserve pain and autonomic physiology are not clear, and thus remain an area of intense investigation. Effects of nVNS vs sham stimulation on subject responses to five noxious thermal stimuli (applied to left lower extremity), were measured in 30 healthy subjects (n = 15 sham and n = 15 nVNS), with fMRI and physiological galvanic skin response (GSR). With repeated noxious thermal stimuli a group × time analysis showed a significantly (p < .001) decreased response with nVNS in bilateral primary and secondary somatosensory cortices (SI and SII), left dorsoposterior insular cortex, bilateral paracentral lobule, bilateral medial dorsal thalamus, right anterior cingulate cortex, and right orbitofrontal cortex. A group × time × GSR analysis showed a significantly decreased response in the nVNS group (p < .0005) bilaterally in SI, lower and mid medullary brainstem, and inferior occipital cortex. Finally, nVNS treatment showed decreased activity in pronociceptive brainstem nuclei (e.g. the reticular nucleus and rostral ventromedial medulla) and key autonomic integration nuclei (e.g. the rostroventrolateral medulla, nucleus ambiguous, and dorsal motor nucleus of the vagus nerve). In aggregate, noninvasive vagal nerve stimulation reduced the physiological response to noxious thermal stimuli and impacted neural circuits important for pain processing and autonomic output.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0201212PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6373934PMC
November 2019

Measuring novel antecedents of mental illness: the Questionnaire of Unpredictability in Childhood.

Neuropsychopharmacology 2019 04 23;44(5):876-882. Epub 2018 Nov 23.

Department of Psychiatry and Human Behavior, University of California, Irvine, CA, USA.

Increasing evidence indicates that, in addition to poverty, maternal depression, and other well-established factors, unpredictability of maternal and environmental signals early in life influences trajectories of brain development, determining risk for subsequent mental illness. However, whereas most risk factors for later vulnerability to mental illness are readily measured using existing, clinically available tools, there are no similar measures for assessing early-life unpredictability. Here we validate the Questionnaire of Unpredictability in Childhood (QUIC) and examine its associations with mental health in the context of other indicators of childhood adversity (e.g., traumatic life events, socioeconomic status, and parenting quality). The QUIC was initially validated through administration to a cohort of adult females (N = 116) and then further refined in two additional independent cohorts (male Veterans, N = 95, and male and female adolescents, N = 175). The QUIC demonstrated excellent internal (α = 0.89) and test-retest reliability (r = 92). Scores on the QUIC were positively correlated with other prospective indicators of exposures to unpredictable maternal inputs in infancy and childhood (unpredictable maternal mood and sensory signals), and accuracy of recall also was confirmed with prospective data. Importantly, the QUIC predicted symptoms of anxiety, depression, and anhedonia in the three study cohorts, and these effects persisted after adjusting for other previously established risk factors. The QUIC, a reliable and valid self-report assessment of exposure to unpredictability in the social, emotional, and physical domains during early life, is a brief, comprehensive, and promising instrument for predicting risk for mental illness.
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http://dx.doi.org/10.1038/s41386-018-0280-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6461958PMC
April 2019

Relations of combat stress and posttraumatic stress disorder to 24-h plasma and cerebrospinal fluid interleukin-6 levels and circadian rhythmicity.

Psychoneuroendocrinology 2019 02 10;100:237-245. Epub 2018 Sep 10.

VA Center of Excellence for Stress and Mental Health, San Diego, CA, USA; VA San Diego Healthcare System, San Diego, CA, USA; Department of Psychiatry, University of California, San Diego (UCSD), CA, USA. Electronic address:

Background: Acute and chronic stress can lead to a dysregulation of the immune response. Growing evidence suggests peripheral immune dysregulation and low-grade systemic inflammation in posttraumatic stress disorder (PTSD), with numerous reports of elevated plasma interleukin-6 (IL-6) levels. However, only a few studies have assessed IL-6 levels in the cerebrospinal fluid (CSF). Most of those have used single time-point measurements, and thus cannot take circadian level variability and CSF-plasma IL-6 correlations into account.

Methods: This study used time-matched, sequential 24-h plasma and CSF measurements to investigate the effects of combat stress and PTSD on physiologic levels and biorhythmicity of IL-6 in 35 male study volunteers, divided in 3 groups: (PTSD = 12, combat controls, CC = 12, and non-deployed healthy controls, HC = 11).

Results: Our findings show no differences in diurnal mean concentrations of plasma and CSF IL-6 across the three comparison groups. However, a significantly blunted circadian rhythm of plasma IL-6 across 24 h was observed in all combat-zone deployed participants, with or without PTSD, in comparison to HC. CSF IL-6 rhythmicity was unaffected by combat deployment or PTSD.

Conclusions: Although no significant group differences in mean IL-6 concentration in either CSF or plasma over a 24-h timeframe was observed, we provide first evidence for a disrupted peripheral IL-6 circadian rhythm as a sequel of combat deployment, with this disruption occurring in both PTSD and CC groups. The plasma IL-6 circadian blunting remains to be replicated and its cause elucidated in future research.
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http://dx.doi.org/10.1016/j.psyneuen.2018.09.009DOI Listing
February 2019

Relations of combat stress and posttraumatic stress disorder to 24-h plasma and cerebrospinal fluid interleukin-6 levels and circadian rhythmicity.

Psychoneuroendocrinology 2019 02 10;100:237-245. Epub 2018 Sep 10.

VA Center of Excellence for Stress and Mental Health, San Diego, CA, USA; VA San Diego Healthcare System, San Diego, CA, USA; Department of Psychiatry, University of California, San Diego (UCSD), CA, USA. Electronic address:

Background: Acute and chronic stress can lead to a dysregulation of the immune response. Growing evidence suggests peripheral immune dysregulation and low-grade systemic inflammation in posttraumatic stress disorder (PTSD), with numerous reports of elevated plasma interleukin-6 (IL-6) levels. However, only a few studies have assessed IL-6 levels in the cerebrospinal fluid (CSF). Most of those have used single time-point measurements, and thus cannot take circadian level variability and CSF-plasma IL-6 correlations into account.

Methods: This study used time-matched, sequential 24-h plasma and CSF measurements to investigate the effects of combat stress and PTSD on physiologic levels and biorhythmicity of IL-6 in 35 male study volunteers, divided in 3 groups: (PTSD = 12, combat controls, CC = 12, and non-deployed healthy controls, HC = 11).

Results: Our findings show no differences in diurnal mean concentrations of plasma and CSF IL-6 across the three comparison groups. However, a significantly blunted circadian rhythm of plasma IL-6 across 24 h was observed in all combat-zone deployed participants, with or without PTSD, in comparison to HC. CSF IL-6 rhythmicity was unaffected by combat deployment or PTSD.

Conclusions: Although no significant group differences in mean IL-6 concentration in either CSF or plasma over a 24-h timeframe was observed, we provide first evidence for a disrupted peripheral IL-6 circadian rhythm as a sequel of combat deployment, with this disruption occurring in both PTSD and CC groups. The plasma IL-6 circadian blunting remains to be replicated and its cause elucidated in future research.
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http://dx.doi.org/10.1016/j.psyneuen.2018.09.009DOI Listing
February 2019

MEG Working Memory N-Back Task Reveals Functional Deficits in Combat-Related Mild Traumatic Brain Injury.

Cereb Cortex 2019 05;29(5):1953-1968

Radiology, Research, and Psychiatry Services, VA San Diego Healthcare System, San Diego, CA, USA.

Combat-related mild traumatic brain injury (mTBI) is a leading cause of sustained cognitive impairment in military service members and Veterans. However, the mechanism of persistent cognitive deficits including working memory (WM) dysfunction is not fully understood in mTBI. Few studies of WM deficits in mTBI have taken advantage of the temporal and frequency resolution afforded by electromagnetic measurements. Using magnetoencephalography (MEG) and an N-back WM task, we investigated functional abnormalities in combat-related mTBI. Study participants included 25 symptomatic active-duty service members or Veterans with combat-related mTBI and 20 healthy controls with similar combat experiences. MEG source-magnitude images were obtained for alpha (8-12 Hz), beta (15-30 Hz), gamma (30-90 Hz), and low-frequency (1-7 Hz) bands. Compared with healthy combat controls, mTBI participants showed increased MEG signals across frequency bands in frontal pole (FP), ventromedial prefrontal cortex, orbitofrontal cortex (OFC), and anterior dorsolateral prefrontal cortex (dlPFC), but decreased MEG signals in anterior cingulate cortex. Hyperactivations in FP, OFC, and anterior dlPFC were associated with slower reaction times. MEG activations in lateral FP also negatively correlated with performance on tests of letter sequencing, verbal fluency, and digit symbol coding. The profound hyperactivations from FP suggest that FP is particularly vulnerable to combat-related mTBI.
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http://dx.doi.org/10.1093/cercor/bhy075DOI Listing
May 2019

Biological profiling of plasma neuropeptide Y in relation to posttraumatic stress symptoms in two combat cohorts.

Biol Psychol 2018 04 19;134:72-79. Epub 2018 Feb 19.

Research Centre, Military Mental Healthcare, Utrecht, The Netherlands; Brain Center Rudolf Magnus, Department of Psychiatry, University Medical Center Utrecht, Utrecht, The Netherlands; Department of Psychiatry, Leiden University Medical Center, Leiden, The Netherlands; Arq, Psychotrauma Expert Group, Diemen, The Netherlands.

In order to decrease the risk of developing stress-related disorders after military deployment, biological vulnerability factors should be identified. Neuropeptide Y (NPY) is a peptide neurotransmitter that is associated with modulation of the stress response. Using the data of two longitudinal prospective cohort studies (N = 892 and N = 2427), plasma NPY (pNPY) was assessed as a possible susceptibility biomarker for the development of PTSD symptoms over time. Data collection started prior to deployment and follow-up assessments were completed up to two years after deployment. In pNPY levels, measured before and shortly after deployment, three distinct trajectories were identified. In both cohorts, these trajectories were not related to the level of reported PTSD symptoms over time and neither were pre-deployment pNPY levels. Whereas previous research suggested that high NPY levels might be a marker for resilience, the current findings suggest limited usefulness of peripherally measured NPY in the development of PTSD.
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http://dx.doi.org/10.1016/j.biopsycho.2018.02.008DOI Listing
April 2018

Traumatic stress and accelerated DNA methylation age: A meta-analysis.

Psychoneuroendocrinology 2018 06 27;92:123-134. Epub 2017 Dec 27.

Department of Psychiatry and Behavioral Sciences, Emory University, United States; Department of Gynecology and Obstetrics, Emory University, United States.

Background: Recent studies examining the association between posttraumatic stress disorder (PTSD) and accelerated aging, as defined by DNA methylation-based estimates of cellular age that exceed chronological age, have yielded mixed results.

Methods: We conducted a meta-analysis of trauma exposure and PTSD diagnosis and symptom severity in association with accelerated DNA methylation age using data from 9 cohorts contributing to the Psychiatric Genomics Consortium PTSD Epigenetics Workgroup (combined N = 2186). Associations between demographic and cellular variables and accelerated DNA methylation age were also examined, as was the moderating influence of demographic variables.

Results: Meta-analysis of regression coefficients from contributing cohorts revealed that childhood trauma exposure (when measured with the Childhood Trauma Questionnaire) and lifetime PTSD severity evidenced significant, albeit small, meta-analytic associations with accelerated DNA methylation age (ps = 0.028 and 0.016, respectively). Sex, CD4T cell proportions, and natural killer cell proportions were also significantly associated with accelerated DNA methylation age (all ps < 0.02). PTSD diagnosis and lifetime trauma exposure were not associated with advanced DNA methylation age. There was no evidence of moderation of the trauma or PTSD variables by demographic factors.

Conclusions: Results suggest that traumatic stress is associated with advanced epigenetic age and raise the possibility that cells integral to immune system maintenance and responsivity play a role in this. This study highlights the need for additional research into the biological mechanisms linking traumatic stress to accelerated DNA methylation age and the importance of furthering our understanding of the neurobiological and health consequences of PTSD.
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http://dx.doi.org/10.1016/j.psyneuen.2017.12.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5924645PMC
June 2018

A signal detection-item response theory model for evaluating neuropsychological measures.

J Clin Exp Neuropsychol 2018 10 5;40(8):745-760. Epub 2018 Feb 5.

a Department of Psychiatry , University of California San Diego , La Jolla , CA , USA.

Introduction: Models from signal detection theory are commonly used to score neuropsychological test data, especially tests of recognition memory. Here we show that certain item response theory models can be formulated as signal detection theory models, thus linking two complementary but distinct methodologies. We then use the approach to evaluate the validity (construct representation) of commonly used research measures, demonstrate the impact of conditional error on neuropsychological outcomes, and evaluate measurement bias.

Method: Signal detection-item response theory (SD-IRT) models were fitted to recognition memory data for words, faces, and objects. The sample consisted of U.S. Infantry Marines and Navy Corpsmen participating in the Marine Resiliency Study. Data comprised item responses to the Penn Face Memory Test (PFMT; N = 1,338), Penn Word Memory Test (PWMT; N = 1,331), and Visual Object Learning Test (VOLT; N = 1,249), and self-report of past head injury with loss of consciousness.

Results: SD-IRT models adequately fitted recognition memory item data across all modalities. Error varied systematically with ability estimates, and distributions of residuals from the regression of memory discrimination onto self-report of past head injury were positively skewed towards regions of larger measurement error. Analyses of differential item functioning revealed little evidence of systematic bias by level of education.

Conclusions: SD-IRT models benefit from the measurement rigor of item response theory-which permits the modeling of item difficulty and examinee ability-and from signal detection theory-which provides an interpretive framework encompassing the experimentally validated constructs of memory discrimination and response bias. We used this approach to validate the construct representation of commonly used research measures and to demonstrate how nonoptimized item parameters can lead to erroneous conclusions when interpreting neuropsychological test data. Future work might include the development of computerized adaptive tests and integration with mixture and random-effects models.
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http://dx.doi.org/10.1080/13803395.2018.1427699DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6050112PMC
October 2018
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