Smaller Hippocampal Volume in Posttraumatic Stress Disorder: A Multisite ENIGMA-PGC Study: Subcortical Volumetry Results From Posttraumatic Stress Disorder Consortia

BACKGROUND

Many studies report smaller hippocampal and amygdala volumes in posttraumatic stress disorder (PTSD), but findings have not always been consistent. Here, we present the results of a large-scale neuroimaging consortium study on PTSD conducted by the Psychiatric Genomics Consortium (PGC)-Enhancing Neuroimaging Genetics through Meta-Analysis (ENIGMA) PTSD Working Group.

METHODS

We analyzed neuroimaging and clinical data from 1868 subjects (794 PTSD patients) contributed by 16 cohorts, representing the largest neuroimaging study of PTSD to date. We assessed the volumes of eight subcortical structures (nucleus accumbens, amygdala, caudate, hippocampus, pallidum, putamen, thalamus, and lateral ventricle). We used a standardized image-analysis and quality-control pipeline established by the ENIGMA consortium.

RESULTS

In a meta-analysis of all samples, we found significantly smaller hippocampi in subjects with current PTSD compared with trauma-exposed control subjects (Cohen's d = -0.17, p = .00054), and smaller amygdalae (d = -0.11, p = .025), although the amygdala finding did not survive a significance level that was Bonferroni corrected for multiple subcortical region comparisons (p < .0063).

CONCLUSIONS

Our study is not subject to the biases of meta-analyses of published data, and it represents an important milestone in an ongoing collaborative effort to examine the neurobiological underpinnings of PTSD and the brain's response to trauma.

CRP polymorphisms and DNA methylation of the AIM2 gene influence associations between trauma exposure, PTSD, and C-reactive protein

BACKGROUND

Recent studies have implicated inflammatory processes in the pathophysiology of posttraumatic stress disorder (PTSD). C-reactive protein (CRP) is a widely-used measure of peripheral inflammation, but little is known about the genetic and epigenetic factors that influence blood levels of C-reactive protein (CRP) in individuals with PTSD.

METHODS

Participants were 286 U.S. military veterans of post-9/11 conflicts (57% with current PTSD). Analyses focused on single nucleotide polymorphisms (SNPs) in the CRP gene and DNA methylation at cg10636246 in AIM2-a locus recently linked to CRP levels through results from a large-scale epigenome-wide association study.

RESULTS

PTSD was positively correlated with serum CRP levels with PTSD cases more likely to have CRP levels in the clinically-elevated range compared to those without a PTSD diagnosis. Multivariate analyses that controlled for white blood cell proportions, genetic principal components, age and sex, showed this association to be mediated by methylation at the AIM2 locus. rs3091244, a functional SNP in the CRP promoter region, moderated the association between lifetime trauma exposure and current PTSD severity. Analyses also revealed that the top SNPs from the largest genome-wide association study of CRP conducted to date (rs1205 and rs2794520) significantly interacted with PTSD to influence CRP levels.

CONCLUSIONS

These findings provide new insights into genetic and epigenetic mechanisms of inflammatory processes in the pathophysiology of PTSD and point to new directions for biomarker identification and treatment development for patients with PTSD.

A comparison of ICD-11 and DSM criteria for posttraumatic stress disorder in two national samples of U.S. military veterans

BACKGROUND

The proposed ICD-11 criteria for posttraumatic stress disorder (PTSD) differ substantially from the DSM-5. ICD-11 eliminated several PTSD symptoms thought to be nonspecific, with the goal of reducing psychiatric comorbidities. However, this change also results in a narrower PTSD definition that may fail to capture individuals with clinically significant PTSD. The purpose of the current study was to compare prevalence and psychiatric comorbidities of DSM (IV/5) and ICD-11 PTSD.

METHODS

We evaluated concordance between DSM (IV/5) and ICD-11 PTSD diagnoses in a web survey of two nationally representative samples of U.S. military veterans (ns = 3517 and 1484). Lifetime and past-month PTSD symptoms were assessed with the DSM-IV-based PTSD Checklist-Specific Stressor version and the DSM-5-based PTSD Checklist-5. Psychiatric comorbidities were assessed using MINI Neuropsychiatric Interview modules.

RESULTS

A significantly greater proportion of veterans met criteria for lifetime and past-month PTSD under DSM-IV/5 than under ICD-11. 21.8-35.9% of those who met criteria under DSM IV/5 did not meet under ICD-11, whereas only 2.4-7.1% of those who met under ICD-11 did not meet under DSM-IV/5. Psychiatric comorbidities did not significantly differ between DSM-IV/5 and ICD-11.

LIMITATIONS

This study relied upon self-report measures of PTSD, distress/impairment, and psychiatric comorbidities.

CONCLUSIONS

The proposed ICD-11 criteria identify fewer PTSD cases than DSM-IV/5 without reducing psychiatric comorbidities. Veterans with clinically significant PTSD symptoms may not meet ICD-11 PTSD criteria, possibly affecting eligibility for healthcare, disability, and other services. The ICD-11 criteria could be revised to capture more PTSD cases before ICD-11 is published in 2018.

Contributions of polygenic risk for obesity to PTSD-related metabolic syndrome and cortical thickness

BACKGROUND

Research suggests that posttraumatic stress disorder (PTSD) is associated with metabolic syndrome (MetS) and that PTSD-associated MetS is related to decreased cortical thickness. However, the role of genetic factors in these associations is unclear. This study evaluated contributions of polygenic obesity risk and PTSD to MetS and of MetS and polygenic obesity risk to cortical thickness.

METHODS

196 white, non-Hispanic veterans of the wars in Iraq and Afghanistan underwent clinical diagnostic interviews, physiological assessments, and genome-wide genotyping; 168 also completed magnetic resonance imaging scans. Polygenic risk scores (PRSs) for obesity were calculated from results of a prior genome-wide association study (Speliotes et al., 2010) and PTSD and MetS severity factor scores were obtained.

RESULTS

Obesity PRS (β=0.15, p=0.009) and PTSD (β=0.17, p=0.005) predicted MetS and interacted such that the association between PTSD and MetS was stronger in individuals with greater polygenic obesity risk (β=0.13, p=0.02). Whole-brain vertex-wise analyses suggested that obesity PRS interacted with MetS to predict decreased cortical thickness in left rostral middle frontal gyrus (β=-0.40, p<0.001).

CONCLUSIONS

Results suggest that PTSD, genetic variability, and MetS are related in a transactional fashion wherein obesity genetic risk increases stress-related metabolic pathology, and compounds the ill health effects of MetS on the brain. Genetic proclivity towards MetS should be considered in PTSD patients when prescribing psychotropic medications with adverse metabolic profiles. Results are consistent with a growing literature suggestive of PTSD-related accelerated aging.

BDNF genotype is associated with hippocampal volume in mild traumatic brain injury

The negative long-term effects of mild traumatic brain injury (mTBI) have been a growing concern in recent years, with accumulating evidence suggesting that mTBI combined with additional vulnerability factors may induce neurodegenerative-type changes in the brain. However, the factors instantiating risk for neurodegenerative disease following mTBI are unknown. This study examined the link between mTBI and brain-derived neurotrophic factor (BDNF) genotype, which has previously been shown to regulate processes involved in neurodegeneration including synaptic plasticity and facilitation of neural survival through its expression. Specifically, we examined nine BDNF single-nucleotide polymorphisms (SNPs; rs908867, rs11030094, rs6265, rs10501087, rs1157659, rs1491850, rs11030107, rs7127507 and rs12273363) previously associated with brain atrophy or memory deficits in mTBI. Participants were 165 white, non-Hispanic Iraq and Afghanistan war veterans between the ages of 19 and 58, 110 of whom had at least one mTBI in their lifetime. Results showed that the BDNF SNP rs1157659 interacted with mTBI to predict hippocampal volume. Furthermore, exploratory analysis of functional resting state data showed that rs1157659 minor allele homozygotes with a history of mTBI had reduced functional connectivity in the default mode network compared to major allele homozygotes and heterozygotes. Apolipoprotein E (APOE) was not a significant predictor of hippocampal volume or functional connectivity. These results suggest that rs1157659 minor allele homozygotes may be at greater risk for neurodegeneration after exposure to mTBI and provide further evidence for a potential role for BDNF in regulating neural processes following mTBI.

Traumatic Stress and Accelerated Cellular Aging: From Epigenetics to Cardiometabolic Disease

PURPOSE OF REVIEW

The aim of this paper is to review the recent literature on traumatic stress-related accelerated aging, including a focus on cellular mechanisms and biomarkers of cellular aging and on the clinical manifestations of accelerated biological aging.

RECENT FINDINGS

Multiple lines of research converge to suggest that PTSD is associated with accelerated aging in the epigenome, and the immune and inflammation systems, and this may be reflected in premature onset of cardiometabolic and cardiovascular disease. The current state of research paves the way for future work focused on identifying the peripheral and central biological mechanisms linking traumatic stress to accelerated biological aging and medical morbidity, with an emphasis on processes involved in inflammation, immune functioning, oxidative stress, autonomic arousal, and stress response. Ultimately, such work could help reduce the pace of biological aging and improve health and wellness.

The correlation of methylation levels measured using Illumina 450K and EPIC BeadChips in blood samples

AIM

We examined concordance of methylation levels across the Illumina Infinium HumanMethylation450 BeadChip and the Infinium MethylationEPIC BeadChip.

METHODS

We computed the correlation for 145 whole blood DNA samples at each of the 422,524 CpG sites measured by both chips.

RESULTS

The correlation at some sites was high (up to r = 0.95), but many sites had low correlation (55% had r < 0.20). The low correspondence between 450K and EPIC measured methylation values at many loci was largely due to the low variability in methylation values for the majority of the CpG sites in blood.

CONCLUSION

Filtering out probes based on the observed correlation or low variability may increase reproducibility of BeadChip-based epidemiological studies.

Posttraumatic stress disorder symptom severity is associated with reduced default mode network connectivity in individuals with elevated genetic risk for psychopathology

BACKGROUND

Accumulating evidence suggests that posttraumatic stress disorder (PTSD) is associated with disrupted default mode network (DMN) connectivity, but findings across studies have not been uniform. Individual differences in relevant genes may account for some of the reported variability in the relationship between DMN connectivity and PTSD. In this study, we investigated this possibility using genome-wide association study (GWAS) derived polygenic risk scores (PRSs) for relevant psychiatric traits. We hypothesized that the association between PTSD and DMN connectivity would be moderated by genetic risk for one or more psychiatric traits such that individuals with elevated polygenic risk for psychopathology and severe PTSD would exhibit disrupted DMN connectivity.

METHODS

Participants were 156 white, non-Hispanic veterans of the wars in Iraq and Afghanistan who were genotyped and underwent resting state functional magnetic resonance imaging and clinical assessment. PRSs for neuroticism, anxiety, major depressive disorder, and cross-disorder risk (based on five psychiatric disorders) were calculated using summary statistics from published large-scale consortia-based GWASs.

RESULTS

Cross-disorder polygenic risk influenced the relationship between DMN connectivity and PTSD symptom severity such that individuals at greater genetic risk showed a significant negative association between PTSD symptom severity and connectivity between the posterior cingulate cortex and right middle temporal gyrus. Polygenic risk for neuroticism, anxiety, and major depressive disorder did not influence DMN connectivity directly or through an interaction with PTSD.

CONCLUSIONS

Findings illustrate the potential power of genome-wide PRSs to advance understanding of the relationship between PTSD and DMN connectivity, a putative neural endophenotype of the disorder.

Reckless Self-Destructive Behavior and PTSD in Veterans: The Mediating Role of New Adverse Events

The addition of self-destructive and reckless behavior as a symptom of posttraumatic stress disorder (PTSD) in DSM-5 has stimulated renewed interest in understanding relationships between these behaviors and trauma-related psychopathology. This study examined the relationship between reckless and self-destructive behaviors (RSDB), intervening exposure to new adverse events, and later PTSD severity in a sample of trauma-exposed veterans. At baseline, participants were assessed for RSDB (past 5 years) and current PTSD severity (N = 222). PTSD severity was then reassessed approximately 4 years later (N = 148). Overall, RSDB were reported by 74.4% of the sample, with 61.3% engaging in multiple forms of RSDB. The most commonly endorsed behaviors included alcohol/drug abuse (42.8%), driving while intoxicated (29.4%), gambling (24.7%), and aggression (23.1%). There was a positive correlation between RSDB and PTSD severity at both the baseline (r = .16, p = .031) and follow-up assessment (r = .24, p = .005). Path models indicated that exposure to new adverse events fully mediated the effect of Time 1 RSDB on PTSD symptoms at Time 2 (indirect association: β = .05, p = .046). Results suggest that RSDB are common among trauma-exposed veterans and may perpetuate PTSD symptoms by increasing exposure to new adverse events.

Mild traumatic brain injury is associated with reduced cortical thickness in those at risk for Alzheimer's disease

Moderate-to-severe traumatic brain injury is one of the strongest environmental risk factors for the development of neurodegenerative diseases such as late-onset Alzheimer's disease, although it is unclear whether mild traumatic brain injury, or concussion, also confers risk. This study examined mild traumatic brain injury and genetic risk as predictors of reduced cortical thickness in brain regions previously associated with early Alzheimer's disease, and their relationship with episodic memory. Participants were 160 Iraq and Afghanistan War veterans between the ages of 19 and 58, many of whom carried mild traumatic brain injury and post-traumatic stress disorder diagnoses. Whole-genome polygenic risk scores for the development of Alzheimer's disease were calculated using summary statistics from the largest Alzheimer's disease genome-wide association study to date. Results showed that mild traumatic brain injury moderated the relationship between genetic risk for Alzheimer's disease and cortical thickness, such that individuals with mild traumatic brain injury and high genetic risk showed reduced cortical thickness in Alzheimer's disease-vulnerable regions. Among males with mild traumatic brain injury, high genetic risk for Alzheimer's disease was associated with cortical thinning as a function of time since injury. A moderated mediation analysis showed that mild traumatic brain injury and high genetic risk indirectly influenced episodic memory performance through cortical thickness, suggesting that cortical thinning in Alzheimer's disease-vulnerable brain regions is a mechanism for reduced memory performance. Finally, analyses that examined the apolipoprotein E4 allele, post-traumatic stress disorder, and genetic risk for schizophrenia and depression confirmed the specificity of the Alzheimer's disease polygenic risk finding. These results provide evidence that mild traumatic brain injury is associated with greater neurodegeneration and reduced memory performance in individuals at genetic risk for Alzheimer's disease, with the caveat that the order of causal effects cannot be inferred from cross-sectional studies. These results underscore the importance of documenting head injuries even within the mild range as they may interact with genetic risk to produce negative long-term health consequences such as neurodegenerative disease.

COMT Val158Met polymorphism moderates the association between PTSD symptom severity and hippocampal volume

BACKGROUND

Memory-based alterations are among the hallmark symptoms of posttraumatic stress disorder (PTSD) and may be associated with the integrity of the hippocampus. However, neuroimaging studies of hippocampal volume in individuals with PTSD have yielded inconsistent results, raising the possibility that various moderators, such as genetic factors, may influence this association. We examined whether the catechol-O-methyltransferase (COMT) Val158Met polymorphism, which has previously been shown to be associated with hippocampal volume in healthy individuals, moderates the association between PTSD and hippocampal volume.

METHODS

Recent war veterans underwent structural MRI on a 3 T scanner. We extracted volumes of the right and left hippocampus using FreeSurfer and adjusted them for individual differences in intracranial volume. We assessed PTSD severity using the Clinician-Administered PTSD Scale. Hierarchical linear regression was used to model the genotype (Val158Met polymorphism) × PTSD severity interaction and its association with hippocampal volume.

RESULTS

We included 146 white, non-Hispanic recent war veterans (90% male, 53% with diagnosed PTSD) in our analyses. A significant genotype × PTSD symptom severity interaction emerged such that individuals with greater current PTSD symptom severity who were homozygous for the Val allele showed significant reductions in left hippocampal volume.

LIMITATIONS

The direction of proposed effects is unknown, thus precluding definitive assessment of whether differences in hippocampal volume reflect a consequence of PTSD, a pre-existing characteristic, or both.

CONCLUSION

Our findings suggest that the COMT polymorphism moderates the association between PTSD and hippocampal volume. These results highlight the role that the dopaminergic system has in brain structure and suggest a possible mechanism for memory disturbance in individuals with PTSD.

Network models of DSM-5 posttraumatic stress disorder: Implications for ICD-11

Recent proposals for revisions to the 11th edition of the International Classification of Diseases (ICD-11) posttraumatic stress disorder (PTSD) diagnostic criteria have argued that the current symptom constellation under the Diagnostic and Statistical Manual of Mental Disorders-5 is unwieldy and includes many symptoms that overlap with other disorders. The newly proposed criteria for the ICD-11 include only 6 symptoms. However, restricting the symptoms to those included in the ICD-11 has implications for PTSD diagnosis prevalence estimates, and it remains unclear whether these 6 symptoms are most strongly associated with a diagnosis of PTSD. Network analytic methods, which assume that psychiatric disorders are networks of interrelated symptoms, provide information regarding which symptoms are most central to a network. We estimated network models of PTSD in a national sample of veterans of the Iraq and Afghanistan wars. In the full sample, the most central symptoms were persistent negative emotional state, efforts to avoid external reminders, efforts to avoid thoughts or memories, inability to experience positive emotions, distressing dreams, and intrusive distressing thoughts or memories; that is, 3 of the 6 most central items to the network would be eliminated from the diagnosis under the current proposal for ICD-11. An empirically defined index summarizing the most central symptoms in the network performed comparably to an index reflecting the proposed ICD-11 PTSD criteria at identifying individuals with an independently assessed DSM-5 defined PTSD diagnosis. Our results highlight the symptoms most central to PTSD in this sample, which may inform future diagnostic systems and treatment. (PsycINFO Database Record

Longitudinal Associations between Posttraumatic Stress Disorder Severity and Personality Disorder Features among Female Rape Survivors

This study evaluated how change in posttraumatic stress disorder (PTSD) symptoms was associated with residualized change in comorbid personality disorder (PD) features and vice versa over the course of 5-10 years. The sample was comprised of 79 female rape survivors who met criteria for PTSD and who were a part of a larger study examining the effects of trauma-focused therapy. PTSD was assessed with the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) version of the Clinician-Administered PTSD Scale [CAPS-IV (1)] and PD features were assessed with the DSM-IV dimensional PD scales on the Schedule for Non-adaptive and Adaptive Personality [SNAP (2)]. PTSD symptom severity and PD features were assessed at baseline and between 5 and 10 years after completing treatment. Multiple regression analyses revealed that PTSD symptom change was related to residualized change in PD severity for paranoid, schizotypal, antisocial, borderline, avoidant, and dependent PD (βs ranged from -0.23 to -0.33; all ps < 0.05). In addition, for borderline and antisocial PDs, longitudinal stability of the PD was attenuated among those with greater PTSD symptom improvement (i.e., the relationship between these PDs over time was altered as a function of PTSD symptom change; βs ranged from -0.27 to -0.29; all ps < 0.05). Similarly, change in severity of paranoid, schizotypal, antisocial, avoidant, and obsessive-compulsive (OC) PD was associated with residualized change in PTSD symptoms (βs ranged from -0.32 to -0.41; all ps < 0.05), and the longitudinal stability of PTSD was attenuated as a product of change in OC PD (β = -0.27; p < 0.02). These findings suggest that these two sets of disorders may impact one another substantially, altering the course of even chronic, characterological conditions. This carries important clinical implications for the treatment of both PTSD and PDs.

Probable Posttraumatic Stress Disorder in the US Veteran Population According to DSM-5: Results From the National Health and Resilience in Veterans Study

OBJECTIVE

With the publication of DSM-5, important changes were made to the diagnostic criteria for posttraumatic stress disorder (PTSD), including the addition of 3 new symptoms. Some have argued that these changes will further increase the already high rates of comorbidity between PTSD and other psychiatric disorders. This study examined the prevalence of DSM-5 PTSD, conditional probability of PTSD given certain trauma exposures, endorsement of specific PTSD symptoms, and psychiatric comorbidities in the US veteran population.

METHODS

Data were analyzed from the National Health and Resilience in Veterans Study (NHRVS), a Web-based survey of a cross-sectional, nationally representative, population-based sample of 1,484 US veterans, which was fielded from September through October 2013. Probable PTSD was assessed using the PTSD Checklist-5.

RESULTS

The weighted lifetime and past-month prevalence of probable DSM-5 PTSD was 8.1% (SE = 0.7%) and 4.7% (SE = 0.6%), respectively. Conditional probability of lifetime probable PTSD ranged from 10.1% (sudden death of close family member or friend) to 28.0% (childhood sexual abuse). The DSM-5 PTSD symptoms with the lowest prevalence among veterans with probable PTSD were trauma-related amnesia and reckless and self-destructive behavior. Probable PTSD was associated with increased odds of mood and anxiety disorders (OR = 7.6-62.8, P < .001), substance use disorders (OR = 3.9-4.5, P < .001), and suicidal behaviors (OR = 6.7-15.1, P < .001).

CONCLUSIONS

In US veterans, the prevalence of DSM-5 probable PTSD, conditional probability of probable PTSD, and odds of psychiatric comorbidity were similar to prior findings with DSM-IV-based measures; we found no evidence that changes in DSM-5 increase psychiatric comorbidity. Results underscore the high rates of exposure to both military and nonmilitary trauma and the high public health burden of DSM-5 PTSD and comorbid conditions in veterans.

Perspectives on the conceptualization of the dissociative subtype of PTSD and implications for treatment

A dissociative subtype of PTSD was added to the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) to denote a distinct presentation of PTSD marked by symptoms of derealization and depersonalization. The subtype has brought renewed interest in the conceptualization of dissociation in PTSD, and raised questions about its treatment. We review the evidence for two models of PTSD-related dissociative symptoms and the treatment approaches that align with each. We find support for the contributions of biologically-based trait-level factors to dissociation, and suggest that empirically supported treatments for PTSD demonstrate efficacy for patients with the subtype.

PTSD, food addiction, and disordered eating in a sample of primarily older veterans: The mediating role of emotion regulation

Posttraumatic stress disorder (PTSD) has been associated with eating disorders (EDs) and addictive behaviors, including the relatively new construct food addiction. However, few studies have investigated mechanisms that account for these associations, and men are underrepresented in studies of EDs and food addiction. We examined whether lifetime PTSD symptoms were associated with current food addiction and ED symptoms, and whether emotion regulation (expressive suppression and cognitive reappraisal), which has been associated with both PTSD and EDs, mediated these relations, in a sample of trauma-exposed, male (n=642) and female (n=55) veterans. Participants were recruited from the Knowledge Networks-GfK Research Panel and completed an online questionnaire. Structural equation modeling revealed that PTSD was directly associated with ED symptoms, food addiction, expressive suppression, and cognitive reappraisal in the full sample and with all constructs except cognitive reappraisal in the male subsample. Expressive suppression was significantly associated with ED symptoms and mediated the PTSD-ED relation. These results highlight the importance of investigating PTSD as a risk factor for food addiction and ED symptoms and the potential mediating role of emotion regulation in the development of PTSD and EDs in order to identify targets for treatments.

Examining weight and eating behavior by sexual orientation in a sample of male veterans

OBJECTIVE

Eating disorders are understudied in men and in sexual minority populations; however, extant evidence suggests that gay men have higher rates of disordered eating than heterosexual men. The present study examined the associations between sexual orientation, body mass index (BMI), disordered eating behaviors, and food addiction in a sample of male veterans.

METHOD

Participants included 642 male veterans from the Knowledge Networks-GfK Research Panel. They were randomly selected from a larger study based on previously reported trauma exposure; 96% identified as heterosexual. Measures included the Eating Disorder Diagnostic Scale, the Yale Food Addiction Scale, and self-reported height and weight.

RESULTS

Heterosexual and sexual minority men did not differ significantly in terms of BMI. However, gay and bisexual men (n=24) endorsed significantly greater eating disorder symptoms and food addiction compared to heterosexual men.

CONCLUSIONS

Our findings that sexual minority male veterans may be more likely to experience eating disorder and food addiction symptoms compared to heterosexual male veterans highlight the importance of prevention, assessment, and treatment efforts targeted to this population.

Longitudinal associations between post-traumatic stress disorder and metabolic syndrome severity

BACKGROUND

Post-traumatic stress disorder (PTSD) is associated with elevated risk for metabolic syndrome (MetS). However, the direction of this association is not yet established, as most prior studies employed cross-sectional designs. The primary goal of this study was to evaluate bidirectional associations between PTSD and MetS using a longitudinal design.

METHOD

A total of 1355 male and female veterans of the conflicts in Iraq and Afghanistan underwent PTSD diagnostic assessments and their biometric profiles pertaining to MetS were extracted from the electronic medical record at two time points (spanning ~2.5 years, n = 971 at time 2).

RESULTS

The prevalence of MetS among veterans with PTSD was just under 40% at both time points and was significantly greater than that for veterans without PTSD; the prevalence of MetS among those with PTSD was also elevated relative to age-matched population estimates. Cross-lagged panel models revealed that PTSD severity predicted subsequent increases in MetS severity (β = 0.08, p = 0.002), after controlling for initial MetS severity, but MetS did not predict later PTSD symptoms. Logistic regression results suggested that for every 10 PTSD symptoms endorsed at time 1, the odds of a subsequent MetS diagnosis increased by 56%.

CONCLUSIONS

Results highlight the substantial cardiometabolic concerns of young veterans with PTSD and raise the possibility that PTSD may predispose individuals to accelerated aging, in part, manifested clinically as MetS. This demonstrates the need to identify those with PTSD at greatest risk for MetS and to develop interventions that improve both conditions.

5-HT2A Gene Variants Moderate the Association between PTSD and Reduced Default Mode Network Connectivity

The default mode network (DMN) has been used to study disruptions of functional connectivity in a wide variety of psychiatric and neurological conditions, including posttraumatic stress disorder (PTSD). Studies indicate that the serotonin system exerts a modulatory influence on DMN connectivity; however, no prior study has examined associations between serotonin receptor gene variants and DMN connectivity in either clinical or healthy samples. We examined serotonin receptor single nucleotide polymorphisms (SNPs), PTSD, and their interactions for association with DMN connectivity in 134 White non-Hispanic veterans. We began by analyzing candidate SNPs identified in prior meta-analyses of relevant psychiatric traits and found that rs7997012 (an HTR2A SNP), implicated previously in anti-depressant medication response in the Sequenced Treatment Alternatives for Depression study (STAR(*)D; McMahon et al., 2006), interacted with PTSD to predict reduced connectivity between the posterior cingulate cortex (PCC) and the right medial prefrontal cortex and right middle temporal gyrus (MTG). rs130058 (HTR1B) was associated with connectivity between the PCC and right angular gyrus. We then expanded our analysis to 99 HTR1B and HTR2A SNPs and found two HTR2A SNPs (rs977003 and rs7322347) that significantly moderated the association between PTSD severity and the PCC-right MTG component of the DMN after correcting for multiple testing. Finally, to obtain a more precise localization of the most significant SNP × PTSD interaction, we performed a whole cortex vertex-wise analysis of the rs977003 effect. This analysis revealed the locus of the pre-frontal effect to be in portions of the superior frontal gyrus, while the temporal lobe effect was centered in the middle and inferior temporal gyri. These findings point to the influence of HTR2A variants on DMN connectivity and advance knowledge of the role of 5-HT2A receptors in the neurobiology of PTSD.

Polygenic Risk for Externalizing Psychopathology and Executive Dysfunction in Trauma-Exposed Veterans

The frequent co-occurrence of antisocial behavior and other disinhibited phenotypes reflects a highly heritable externalizing spectrum. We examined the molecular genetic basis of this spectrum by testing polygenic associations with psychopathology symptoms, impulsive traits, and cognitive functions in two samples of primarily military veterans (n =537, n =194). We also investigated whether polygenic risk for externalizing moderated the effects of trauma on these phenotypes. As hypothesized, polygenic risk positively predicted externalizing psychopathology and negatively predicted performance on inhibitory control tasks. Gene-by-environment effects were also evident, with trauma exposure predicting greater impulsivity and less working memory capacity, but only at high levels of genetic liability. As expected, polygenic risk was not associated with internalizing psychopathology or episodic memory performance. This is the first independent replication of the polygenic score as a measure of genetic predispositions for externalizing and provides preliminary evidence that executive dysfunction is a heritable vulnerability for externalizing psychopathology.

EPIGENETIC VARIATION AT SKA2 PREDICTS SUICIDE PHENOTYPES AND INTERNALIZING PSYCHOPATHOLOGY

BACKGROUND

DNA methylation of the SKA2 gene has recently been implicated as a biomarker of suicide risk and posttraumatic stress disorder (PTSD). To examine the specificity and reliability of these findings, we examined associations between SKA2 DNA methylation, broad dimensions of psychiatric symptoms, and suicide phenotypes in adults with high levels of trauma exposure.

METHODS

A total of 466 White, non-Hispanic veterans and their intimate partners (65% male) underwent clinical assessment and had blood drawn for genotyping and methylation analysis. DNA methylation of the CpG locus cg13989295 and genotype at the methylation-associated single-nucleotide polymorphism (SNP) rs7208505 were examined in relation to current and lifetime PTSD, internalizing and externalizing psychopathology, and suicide phenotypes (ideation, plans, and attempts).

RESULTS

DNA methylation at the previously implicated SKA2 CpG locus (cg13989295) was associated with current and lifetime symptoms of internalizing (but not externalizing) disorders. SKA2 methylation levels also predicted higher rates of current suicidal thoughts and behaviors, even after including well-established psychiatric risk factors for suicide in the model. Associations between PTSD and SKA2 were not significant, and genetic variation at the methylation-associated SNP (rs7208505) was not related to any of the phenotypes examined.

CONCLUSIONS

SKA2 methylation may index a general propensity to experience stress-related psychopathology, including internalizing disorders and suicidal thoughts and behaviors. This study demonstrates that SKA2 methylation levels explain unique variance in suicide risk not captured by clinical symptom interviews, providing further evidence of its potential utility as a biomarker of suicide risk and stress-related psychopathology.

PTSD-Related Cardiovascular Disease and Accelerated Cellular Aging

We reviewed the literature from 2010 to 2016 on the relationship between posttraumatic stress disorder (PTSD) and cardiometabolic health conditions, including metabolic syndrome, coronary artery disease, stroke, and myocardial infarction, among others. Collectively, PTSD was associated with increased risk of cardiometabolic health problems, with pre-clinical and clinical studies offering evidence of behavioral (e.g., poor sleep, cigarette use, poor diet and insufficient exercise) and biological (e.g., autonomic reactivity, inflammation) mediators of these associations. We discuss the possibility that these behavioral and biological mechanisms lead to accelerated cellular aging, as regulated in the epigenome, which contributes to premature cardiometabolic health decline. This has implications for the assessment, prevention, and treatment of cardiometabolic conditions among those with PTSD. It also highlights the need to better understand the mechanisms linking PTSD to accelerated aging and to develop interventions to attenuate or reverse this phenomenon.

Using the WHODAS 2.0 to Assess Functioning Among Veterans Seeking Compensation for Posttraumatic Stress Disorder

OBJECTIVE

One of the major changes in DSM-5 was removal of the Global Assessment of Functioning (GAF). To determine whether the World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0) is a suitable replacement for the GAF, this study compared how well the WHODAS 2.0 and the GAF measured functional impairment and other phenomena related to posttraumatic stress disorder (PTSD) among veterans applying for financial compensation (service connection) for PTSD.

METHODS

Clinicians evaluating veteran claimants administered the Clinician Administered PTSD Scale (CAPS) and the WHODAS 2.0 to 177 veterans during their evaluations. Veterans also completed the Inventory of Psychosocial Functioning (IPF), a self-report measure of functional impairment, and received a GAF rating from the examiner. Actual benefit determinations and ratings were obtained.

RESULTS

Confirmatory factor analyses demonstrated that the WHODAS 2.0 and the IPF were stronger indicators of a latent variable reflecting functioning compared with the GAF. In receiver operating characteristic curve analyses, the WHODAS 2.0, IPF, and GAF all displayed similar ability to identify veterans with PTSD-related impairment assessed by the CAPS. Compared with the GAF, the WHODAS 2.0 and IPF were less strongly related to PTSD symptom severity and disability ratings by the U.S. Department of Veterans Affairs, but these variables are typically influenced by GAF scores.

CONCLUSIONS

The WHODAS 2.0 and IPF are acceptable replacements for the GAF and can be used to assess functional impairment among veterans seeking compensation for PTSD.