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.

A novel locus in the oxidative stress-related gene ALOX12 moderates the association between PTSD and thickness of the prefrontal cortex

Oxidative stress has been implicated in many common age-related diseases and is hypothesized to play a role in posttraumatic stress disorder (PTSD)-related neurodegeneration (Miller and Sadeh, 2014). This study examined the influence of the oxidative stress-related genes ALOX 12 and ALOX 15 on the association between PTSD and cortical thickness. Factor analyses were used to identify and compare alternative models of the structure of cortical thickness in a sample of 218 veterans. The best-fitting model was then used for a genetic association analysis in White non-Hispanic participants (n=146) that examined relationships between 33 single nucleotide polymorphisms (SNPs) spanning the two genes, 8 cortical thickness factors, and each SNP×PTSD interaction. Results identified a novel ALOX12 locus (indicated by two SNPs in perfect linkage disequilibrium: rs1042357 and rs10852889) that moderated the association between PTSD and reduced thickness of the right prefrontal cortex. A whole-cortex vertex-wise analysis showed this effect to be localized to clusters spanning the rostral middle frontal gyrus, superior frontal gyrus, rostral anterior cingulate cortex, and medial orbitofrontal cortex. These findings illustrate a novel factor-analytic approach to neuroimaging-genetic analyses and provide new evidence for the possible involvement of oxidative stress in PTSD-related neurodegeneration.

The Dissociative Subtype of PTSD Scale: Initial Evaluation in a National Sample of Trauma-Exposed Veterans

The fifth edition of the Diagnostic and Statistical Manual includes a dissociative subtype of posttraumatic stress disorder, but no existing measures specifically assess it. This article describes the initial evaluation of a 15-item self-report measure of the subtype called the Dissociative Subtype of Posttraumatic Stress Disorder Scale (DSPS) in an online survey of 697 trauma-exposed military veterans representative of the U.S. veteran population. Exploratory factor analyses of the lifetime DSPS items supported the intended structure of the measure consisting of three factors reflecting derealization/depersonalization, loss of awareness, and psychogenic amnesia. Consistent with prior research, latent profile analyses assigned 8.3% of the sample to a highly dissociative class distinguished by pronounced symptoms of derealization and depersonalization. Overall, results provide initial psychometric support for the lifetime DSPS scales; additional research in clinical and community samples is needed to further validate the measure.

The influence of the dissociative subtype of posttraumatic stress disorder on treatment efficacy in female veterans and active duty service members

OBJECTIVE

A dissociative subtype of posttraumatic stress disorder (PTSD) was recently added to the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; American Psychiatric Association, 2013) and is thought to be associated with poor PTSD treatment response.

METHOD

We used latent growth curve modeling to examine data from a randomized controlled trial of prolonged exposure and present-centered therapy for PTSD in a sample of 284 female veterans and active duty service members with PTSD to test the association between the dissociative subtype and treatment response.

RESULTS

Individuals with the dissociative subtype (defined using latent profile analysis) had a flatter slope (p = .008) compared with those with high PTSD symptoms and no dissociation, such that the former group showed, on average, a 9.75 (95% confidence interval [-16.94, -2.57]) lesser decrease in PTSD severity scores on the Clinician Administered PTSD Scale (Blake et al., 1995) over the course of the trial. However, this effect was small in magnitude. Dissociative symptoms decreased markedly among those with the subtype, though neither treatment explicitly addressed such symptoms. There were no differences as a function of treatment type.

CONCLUSIONS

Results raise doubt about the common clinical perception that exposure therapy is not effective or appropriate for individuals who have PTSD and dissociation, and provide empirical support for the use of exposure treatment for individuals with the dissociative subtype of PTSD.

An analysis of gene expression in PTSD implicates genes involved in the glucocorticoid receptor pathway and neural responses to stress

We examined the association between posttraumatic stress disorder (PTSD) and gene expression using whole blood samples from a cohort of trauma-exposed white non-Hispanic male veterans (115 cases and 28 controls). 10,264 probes of genes and gene transcripts were analyzed. We found 41 that were differentially expressed in PTSD cases versus controls (multiple-testing corrected p<0.05). The most significant was DSCAM, a neurological gene expressed widely in the developing brain and in the amygdala and hippocampus of the adult brain. We then examined the 41 differentially expressed genes in a meta-analysis using two replication cohorts and found significant associations with PTSD for 7 of the 41 (p<0.05), one of which (ATP6AP1L) survived multiple-testing correction. There was also broad evidence of overlap across the discovery and replication samples for the entire set of genes implicated in the discovery data based on the direction of effect and an enrichment of p<0.05 significant probes beyond what would be expected under the null. Finally, we found that the set of differentially expressed genes from the discovery sample was enriched for genes responsive to glucocorticoid signaling with most showing reduced expression in PTSD cases compared to controls.

Negative emotionality and disconstraint influence PTSD symptom course via exposure to new major adverse life events

Identifying the factors that influence stability and change in chronic posttraumatic stress disorder (PTSD) is important for improving clinical outcomes. Using a cross-lagged design, we analyzed the reciprocal effects of personality and PTSD symptoms over time and their effects on stress exposure in a sample of 222 trauma-exposed veterans (ages 23-68; 90.5% male). Personality functioning and PTSD were measured approximately 4 years apart, and self-reported exposure to major adverse life events during the interim was also assessed. Negative emotionality positively predicted future PTSD symptoms, and this effect was partially mediated by exposure to new events. Constraint (negatively) indirectly affected PTSD via its association with exposure to new events. There were no significant effects of positive emotionality nor did PTSD symptom severity exert influences on personality over time. Results indicate that high negative affect and disconstraint influence the course of PTSD symptoms by increasing exposure to stressful life events.

ICD-11 Complex PTSD in US National and Veteran Samples: Prevalence and Structural Associations with PTSD

The eleventh edition of the International Classification of Diseases (ICD-11) is under development and current proposals include major changes to trauma-related psychiatric diagnoses, including a heavily restricted definition of posttraumatic stress disorder (PTSD) and the addition of complex PTSD (CPTSD). We aimed to test the postulates of CPTSD in samples of 2695 community participants and 323 trauma-exposed military veterans. CPTSD prevalence estimates were 0.6% and 13% in the community and veteran samples, respectively; one-quarter to one-half of those with PTSD met criteria for CPTSD. There were no differences in trauma exposure across diagnoses. A factor mixture model with two latent dimensional variables and four latent classes provided the best fit in both samples: classes differed by their level of symptom severity but did not differ as a function of the proposed PTSD versus CPTSD diagnoses. These findings should raise concerns about the distinctions between CPTSD and PTSD proposed for ICD-11.

Posttraumatic stress disorder in the US veteran population: results from the National Health and Resilience in Veterans Study

OBJECTIVE

To describe the prevalence of posttraumatic stress disorder (PTSD) and comorbid psychiatric disorders and identify correlates of PTSD in a contemporary, nationally representative sample of US veterans.

METHOD

Data were analyzed from Wave 1 of the National Health and Resilience in Veterans Study, a cross-sectional, retrospective, web-based survey of a population-based sample of 3,157 US veterans conducted between October and December 2011. The main outcome measure was probable lifetime PTSD, which was assessed by using a DSM-IV version of the PTSD Checklist (PCL), the PCL-Specific Stressor version.

RESULTS

The weighted lifetime and current prevalence of probable PTSD was 8.0% (standard error [SE] = 0.48) and 4.8% (SE = 0.40), respectively. 87.0% of veterans reported exposure to at least 1 potentially traumatic event (PTE); veterans reported a mean of 3.4 (SD = 2.8) different PTE types in their lifetime. Sudden death of a loved one was the most frequently endorsed PTE (61.3%), and sexual abuse in adulthood had the highest conditional probability of PTSD (37.3%). PTSD was associated with increased odds of mood, anxiety, and substance use disorders (odds ratios [ORs] = 2.2-19.1, P values < .001); suicidal ideation (OR = 9.7, P < .001); and suicide attempts (OR = 11.8, P < .001). Psychosocial factors, including resilience, community integration, and secure attachment, were associated with decreased odds of PTSD (ORs = 0.5-0.7, P values < .05).

CONCLUSIONS

In a nationally representative sample of US veterans, the prevalence of lifetime and current PTSD was 8.0% and 4.8%, respectively, and PTSD was associated with elevated risk for several psychiatric conditions and suicidality. Veterans reported exposure to many PTE types in addition to combat, and conditional risk for PTSD was high for noncombat-related trauma. Prevention and treatment efforts designed to bolster protective psychosocial factors may help mitigate PTSD risk in this population.

Association of eating disorder symptoms with internalizing and externalizing dimensions of psychopathology among men and women

OBJECTIVE

A large body of factor analytic research supports the idea that common mental disorders are organized along correlated latent dimensions termed internalizing and externalizing. Eating disorders (EDs) have been associated with both internalizing (mood and anxiety disorders) and externalizing (substance use, antisocial personality disorder) forms of psychopathology. Previous studies found that EDs are most strongly related to internalizing disorders. However, no previous factor analytic studies of EDs and the internalizing/externalizing dimensions have evaluated if EDs align with these spectra similarly for men and women. We examined the location of anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED) symptoms within this model of psychopathology among a sample of veterans, a population traditionally understudied in EDs.

METHOD

Data were from two studies of veterans and their intimate partners (N = 453 men and 307 women). Participants were administered the Structured Clinical Interview for DSM-IV without skip-outs. Lifetime symptom severity scores were used in confirmatory factor analytic models.

RESULTS

A model with AN, BN, and BED symptoms loading onto the distress subfactor of the internalizing domain fit the data best in the full sample and the male and female subsamples. This model was statistically equivalent for men and women.

DISCUSSION

All three EDs loaded onto distress, indicating that these conditions overlap with psychopathology characterized by negative affect. Investigating latent dimensions of psychopathology is one approach to identifying common factors that partially account for patterns of comorbidity among psychiatric disorders, which may aid in translating research findings into clinical practice.

The dopamine D3 receptor gene and posttraumatic stress disorder

The dopamine D3 receptor (DRD3) gene has been implicated in schizophrenia, autism, and substance use-disorders and is related to emotion reactivity, executive functioning, and stress-responding, processes impaired in posttraumatic stress disorder (PTSD). The aim of this candidate gene study was to evaluate DRD3 polymorphisms for association with PTSD. The discovery sample was trauma-exposed White, non-Hispanic U.S. veterans and their trauma-exposed intimate partners (N = 491); 60.3% met criteria for lifetime PTSD. The replication sample was 601 trauma-exposed African American participants living in Detroit, Michigan; 23.6% met criteria for lifetime PTSD. Genotyping was based on high-density bead chips. In the discovery sample, 4 single nucleotide polymorphisms (SNPs), rs2134655, rs201252087, rs4646996, and rs9868039, showed evidence of association with PTSD and withstood correction for multiple testing. The minor alleles were associated with reduced risk for PTSD (OR range = 0.59 to 0.69). In the replication sample, rs2251177, located 149 base pairs away from the most significant SNP in the discovery sample, was nominally associated with PTSD in men (OR = 0.32). Although the precise role of the D3 receptor in PTSD is not yet known, its role in executive functioning and emotional reactivity, and the sensitivity of the dopamine system to environmental stressors could potentially explain this association.

Intermittent explosive disorder: associations with PTSD and other Axis I disorders in a US military veteran sample

This study examined the prevalence of intermittent explosive disorder (IED) and its associations with trauma exposure, posttraumatic stress disorder (PTSD), and other psychiatric diagnoses in a sample of trauma-exposed veterans (n=232) with a high prevalence of PTSD. Structural associations between IED and latent dimensions of internalizing and externalizing psychopathology were also modeled to examine the location of IED within this influential structure. Twenty-four percent of the sample met criteria for a lifetime IED diagnosis and those with the diagnosis were more likely to meet criteria for lifetime PTSD than those without (30.3% vs. 14.3% respectively). Furthermore, regression analyses revealed lifetime PTSD severity to be a significant predictor of IED severity after controlling for combat, trauma exposure, and age. Finally, confirmatory factor analysis revealed significant cross-loadings of IED on both the externalizing and distress dimensions of psychopathology, suggesting that the association between IED and other psychiatric disorders may reflect underlying tendencies toward impulsivity and aggression and generalized distress and negative emotionality, respectively.

Combat exposure severity as a moderator of genetic and environmental liability to post-traumatic stress disorder

BACKGROUND

Twin studies of veterans and adults suggest that approximately 30-46% of the variance in post-traumatic stress disorder (PTSD) is attributable to genetic factors. The remaining variance is attributable to the non-shared environment, which, by definition, includes combat exposure. This study used a gene by measured environment twin design to determine whether the effects of genetic and environmental factors that contribute to the etiology of PTSD are dependent on the level of combat exposure.

METHOD

The sample was drawn from the Vietnam Era Twin Registry (VETR) and included 620 male-male twin pairs who served in the US Military in South East Asia during the Vietnam War era. Analyses were based on data from a clinical diagnostic interview of lifetime PTSD symptoms and a self-report measure of combat exposure.

RESULTS

Biometric modeling revealed that the effects of genetic and non-shared environment factors on PTSD varied as a function of level of combat exposure such that the association between these factors and PTSD was stronger at higher levels of combat exposure.

CONCLUSIONS

Combat exposure may act as a catalyst that augments the impact of hereditary and environmental contributions to PTSD. Individuals with the greatest exposure to combat trauma were at increased risk for PTSD as a function of both genetic and environmental factors. Additional work is needed to determine the biological and environmental mechanisms driving these associations.

A genome-wide association study of clinical symptoms of dissociation in a trauma-exposed sample

BACKGROUND

Recent work suggests that a subset of individuals with posttraumatic stress disorder (PTSD) exhibit marked dissociative symptoms, as defined by derealization and depersonalization. A dissociative subtype of PTSD was added to the diagnostic criteria listed in the Diagnostic and Statistical Manual of Mental Disorders, Version 5 (DSM-5) to capture this presentation of PTSD. This study examined genetic polymorphisms for association with the symptoms that define the dissociative subtype of PTSD using a genome-wide approach.

METHODS

The sample comprised 484 White, non-Hispanic, trauma-exposed veterans and their partners who were assessed for lifetime PTSD and dissociation using a structured clinical interview. The prevalence of PTSD was 60.5%. Single-nucleotide polymorphisms (SNPs) from across the genome were obtained from a 2.5 million SNP array.

RESULTS

Ten SNPs evidenced suggestive association with dissociation (P < 10(-5)). No SNPs met genome-wide significance criteria (P < 5 × 10(-8)). The peak SNP was rs263232 (β = 1.4, P = 6.12 × 10(-7)), located in the adenylyl cyclase 8 (ADCY8) gene; a second SNP in the suggestive range was rs71534169 (β = 1.63, P = 3.79 × 10(-6)), located in the dipeptidyl-peptidase 6 (DPP6) gene.

CONCLUSIONS

ADCY8 is integral for long-term potentiation and synaptic plasticity and is implicated in fear-related learning and memory and long-term memory consolidation. DPP6 is critical for synaptic integration and excitation. These genes may exert effects on basic sensory integration and cognitive processes that underlie dissociative phenomena.

Latent class analysis of personality disorders in adults with posttraumatic stress disorder: results from the National Epidemiologic Survey on Alcohol and Related Conditions

OBJECTIVE

To characterize predominant typologies of co-occurring personality disorders among adults with posttraumatic stress disorder (PTSD) and examine their relation to Axis I comorbidities, health-related quality of life, and course and treatment of PTSD.

METHOD

Latent class analysis was conducted on the 10 DSM-IV personality disorders in a nationally representative sample of 2,463 adults with a lifetime diagnosis of PTSD from Wave 2 (2004-2005) of the National Epidemiologic Survey on Alcohol and Related Conditions.

RESULTS

Three latent classes of personality disorders were identified: a borderline-dysregulated class (11.4%), an obsessive-paranoid class (13.1%), and a no/low personality disorders class (75.5%). The borderline-dysregulated and obsessive-paranoid classes were more likely than the no/low personality disorder class to have a broad range of comorbid Axis I diagnoses and to have ever attempted suicide (ORs = 1.50-8.01), and they reported lower mental health-related quality of life. The borderline-dysregulated class was less likely than the no/low personality disorder class to have experienced remission of their most recent episode of PTSD (OR = 0.54; 95% CI, 0.38-0.75) and was more likely to have been prescribed medication for PTSD (OR = 1.65; 95% CI, 1.20-2.28) and to have used alcohol and drugs to mitigate their PTSD symptoms (OR = 2.77; 95% CI, 1.62-4.74). The obsessive-paranoid class was more likely than the no/low personality disorders class to report sexual assault as their worst trauma (OR = 2.22; 95% CI, 1.36-3.61) and had an earlier age at onset of PTSD symptoms compared to the other 2 classes.

CONCLUSIONS

Among US adults with PTSD, the 10 DSM-IV personality disorders can be classified into 3 "person-based" typologies, which are differentially associated with comorbid Axis I disorders, mental health-related quality of life, and clinical and treatment characteristics of this disorder. These results suggest that comprehensive assessment of personality disorders may help inform etiologic models and treatment approaches for PTSD.

Corticotropin releasing hormone receptor 2 (CRHR-2) gene is associated with decreased risk and severity of posttraumatic stress disorder in women

BACKGROUND

The corticotropin releasing hormone (CRH) system has been implicated in a variety of anxiety and mood-based symptoms and disorders. CRH receptor-2 (CRHR-2) plays a role in attenuating biological responses to stressful life events and trauma, making the CRHR-2 gene a strong candidate to study in relationship to PTSD.

METHODS

The sample was 491 trauma-exposed white non-Hispanic veterans and their cohabitating intimate partners assessed via structured interview for lifetime DSM-IV PTSD; just over 60% met criteria for the disorder. Thirty-one single nucleotide polymorphisms (SNPs) in and near CRHR-2, obtained from an array of 2.5 million markers, were tested for association with PTSD diagnosis and symptom severity in the whole sample and in men and women separately.

RESULTS

Ten SNPs showed nominally significant evidence of association with PTSD in the full sample and two SNPs (rs8192496 and rs2190242) were significant after permutation-based multiple testing correction (uncorrected ps = .0004 and .0005, odds ratios = .60 and .58, respectively). Analyses stratified by sex revealed that the effect was specific to women, who comprised 35% of the sample (uncorrected ps = .0003 and .0002, odds ratios = .41 and .35, respectively). Two additional SNPs (rs2267715 and rs2284218) also showed significant association with PTSD in women (both uncorrected ps = .001, both odds ratios = .48).

CONCLUSIONS

Results suggest that CRHR-2 variants may affect risk for PTSD in women by attenuating the stress response and reducing symptoms of the disorder.

Sample Size Requirements for Structural Equation Models: An Evaluation of Power, Bias, and Solution Propriety

Determining sample size requirements for structural equation modeling (SEM) is a challenge often faced by investigators, peer reviewers, and grant writers. Recent years have seen a large increase in SEMs in the behavioral science literature, but consideration of sample size requirements for applied SEMs often relies on outdated rules-of-thumb. This study used Monte Carlo data simulation techniques to evaluate sample size requirements for common applied SEMs. Across a series of simulations, we systematically varied key model properties, including number of indicators and factors, magnitude of factor loadings and path coefficients, and amount of missing data. We investigated how changes in these parameters affected sample size requirements with respect to statistical power, bias in the parameter estimates, and overall solution propriety. Results revealed a range of sample size requirements (i.e., from 30 to 460 cases), meaningful patterns of association between parameters and sample size, and highlight the limitations of commonly cited rules-of-thumb. The broad "lessons learned" for determining SEM sample size requirements are discussed.

Psychological effects of the marathon bombing on Boston-area veterans with posttraumatic stress disorder

This study examined the psychological impact of the Boston Marathon bombing using data from an ongoing longitudinal study of Boston-area veterans with posttraumatic stress disorder (PTSD; N = 71). Participants were assessed by telephone within 1 week of the end of the event; 42.3% of participants reported being personally affected by the bombings and/or the manhunt that followed. The majority of them reported that the bombing reminded them of their own traumas and/or caused other emotional distress. Examination of change in posttraumatic stress disorder (PTSD) symptoms from a prebombing assessment an average of 2 months earlier to 1 week after the event revealed no significant change in symptoms across the sample as a whole. However, examination of patterns of change at the individual level revealed significant correlations (r = .33; p = .005) between distress at the time of the event and change in total PTSD symptom severity, with this effect accounted for primarily by increases in intrusion and avoidance symptoms (rs = .35 and .31, ps = .002 and .008, respectively). Findings of this study should raise awareness of the potential impact of terror attacks, mass shootings, and other events of this type on the well-being of individuals with histories of trauma and/or pre-existing PTSD.

The retinoid-related orphan receptor alpha (RORA) gene and fear-related psychopathology

BACKGROUND

This study followed on findings from a recent genome-wide association study of PTSD that implicated the retinoid-related orphan receptor alpha (RORA) gene (Logue et al., 2012) by examining its relationship to broader array of disorders.

METHODS

Using data from the same cohort (N=540), we analyzed patterns of association between 606 single nucleotide polymorphisms (SNPs) spanning the RORA gene and comorbidity factors termed fear, distress (i.e., internalizing factors) and externalizing.

RESULTS

Results showed that rs17303244 was associated with the fear component of internalizing (i.e., defined by symptoms of panic, agoraphobia, specific phobia, and obsessive-compulsive disorder) at a level of significance that withstood correction for gene-wide multiple testing.

LIMITATIONS

The primary limitations were the modest size of the cohort and the absence of a replication sample.

CONCLUSIONS

Results add to a growing literature implicating the RORA gene in a wide range of neuropsychiatric disorders and offer new insight into possible molecular mechanisms of the effects of traumatic stress on the brain and the role of genetic factors in those processes.