The structure of co-occurring PTSD and depression symptoms in a cohort of Marines pre- and post-deployment

Long-term trajectories of depressive symptoms in deployed military personnel: A 10-year prospective study

BACKGROUND

Military missions, especially those involving combat exposure, are associated with an increased risk of depression. Understanding the long-term course of depressive symptoms post-deployment is important to improve decision-making regarding deployment and mental health policies in the military. This study investigates trajectories of depressive symptoms in the Dutch army, exploring the influence of factors such as demographics, early-life trauma, posttraumatic stress disorder (PTSD) symptoms, and deployment stressors.

METHODS

A cohort of 1032 military men and women deployed to Afghanistan (2005-2008) was studied from pre- to 10 years post-deployment. Depressive and PTSD symptoms were assessed using the Symptom CheckList-90 and the Self-Rating Inventory for PTSD. Demographics, early trauma, and deployment experiences were collected at baseline and after deployment, respectively. Latent Class Growth Analysis was used to explore heterogeneity in trajectories of depressive symptoms over time.

RESULTS

Four trajectories were found: resilient (65%), intermediate-stable (20%), symptomatic-chronic (9%), and late-onset-increasing (6%). The resilient group experienced fewer deployment stressors, while the symptomatic-chronic group reported more early life traumas. Trajectories with elevated depressive symptoms consistently demonstrated higher PTSD symptoms.

LIMITATIONS

Potential nonresponse bias and missing information due to the longitudinal design and extensive follow-up times.

CONCLUSIONS

This study identified multiple trajectories of depressive symptoms in military personnel up to 10 years post-deployment, associated with early trauma, deployment stressors, adverse life events and PTSD symptoms. The prevalence of the resilient trajectory suggests a substantial level of resilience among deployed military personnel. These findings provide valuable insights and a foundation for further research.

The Influence of Transdiagnostic Vulnerability Factors on PTSD Symptom Clusters in a Veteran Sample

BACKGROUND

There is continuing debate as to the latent structure underpinning posttraumatic stress disorder symptomatology. The transdiagnostic vulnerability factors of negative affect, anxiety sensitivity (and subcomponents) and intolerance of uncertainty have previously demonstrated the ability to explain symptom clusters in a range of anxiety and depressive disorders, and may give further understanding of PTSD symptomatology.

METHOD

Within an Australian Defence Force veteran population, structural equation modeling is utilized to assess whether a hierarchical Original Model containing negative affect as the general cognitive factor, anxiety sensitivity and intolerance of uncertainty as mid-level factors, can explain variability among posttraumatic stress disorder symptom clusters as defined by the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. A further hierarchical Anxiety Sensitivity Extended model consisting of the general cognitive factor of negative affect and the three sub-factors of anxiety sensitivity as mid-level factors was also tested upon PTSD symptom clusters.

RESULTS

Both the hierarchical Original and Anxiety Sensitivity Extended models fit the data well. Within both models, negative affect consistently showed significant direct effects upon the posttraumatic stress disorder symptom clusters. In the Original Model, anxiety sensitivity served as a significant mediator of negative affect for several symptom clusters, while intolerance of uncertainty was non-significant both as a direct effect and as a mediator of negative affect. In the Anxiety Sensitivity Extended Model, the cognitive concerns sub-factor of anxiety sensitivity served as a significant mediator of negative affect for several symptom clusters, while the social and physical concerns sub-factors did not have significant direct or mediating effects.

CONCLUSIONS

This study demonstrates a transdiagnostic hierarchical model significantly explains the severity of Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition posttraumatic stress disorder symptom constructs within a subclinical population. Negative affect and anxiety sensitivity can each be targeted with specific interventions, suggesting new avenues to augment current gold standard psychotherapeutic interventions.

The cost of being absent: Is meta-awareness of mind-wandering related to depression symptom severity, rumination tendencies and trauma intrusions?

BACKGROUND

Deng, Li and Tang (2014) reported that depression symptom severity is negatively associated with dispositional mindfulness and importantly, positively associated with zone-outs (mind-wandering without meta-awareness). We replicated and extended their study by exploring possible explanations for these relationships, and by also investigating whether mind-wandering is related to (1) trait rumination subtype-brooding, depressive or reflective, and (2) trauma intrusions-a hallmark PTSD symptom, since both rumination and trauma intrusions strongly correlate with depression. We also explored if dispositional mindfulness-the opposing construct of mind-wandering-mediated these relationships.

METHOD

Two hundred participants completed mindfulness tendency and depression severity measures, counterbalanced with the Sustained Attention to Response Task (SART)-including thought probes to index behavioral mind-wandering (target-error frequency), subjective mind-wandering and meta-awareness-then the rumination style and trauma intrusion frequency measures.

RESULTS

Depression scores positively correlated with mind-wandering with and without meta-awareness and with SART target-error rates, and negatively correlated with dispositional mindfulness. Further, trait brooding positively correlated with mind-wandering without meta-awareness. Dispositional mindfulness mediated the relationships between brooding and depression, and depression and mind-wandering, and also negatively correlated with trauma intrusion frequency.

LIMITATIONS

Limitations include measurement and mind-wandering definitions, and an inability to make causal claims.

CONCLUSIONS

People experiencing greater depression symptomology, and/or who have a greater tendency to brood, mind-wandered more often. Further, people who experience more trauma intrusions tend to be less mindful. These results point to potential harmful effects of mind-wandering through people's reduced propensity to be mindful, facilitating a negative self-referenced cognitive loop that may maintain or increase depression.

Gene Expression Analysis in Three Posttraumatic Stress Disorder Cohorts Implicates Inflammation and Innate Immunity Pathways and Uncovers Shared Genetic Risk With Major Depressive Disorder

Posttraumatic stress disorder (PTSD) is a complex psychiatric disorder that can develop following exposure to traumatic events. The Psychiatric Genomics Consortium PTSD group (PGC-PTSD) has collected over 20,000 multi-ethnic PTSD cases and controls and has identified both genetic and epigenetic factors associated with PTSD risk. To further investigate biological correlates of PTSD risk, we examined three PGC-PTSD cohorts comprising 977 subjects to identify differentially expressed genes among PTSD cases and controls. Whole blood gene expression was quantified with the HumanHT-12 v4 Expression BeadChip for 726 OEF/OIF veterans from the Veterans Affairs (VA) Mental Illness Research Education and Clinical Center (MIRECC), 155 samples from the Injury and Traumatic Stress (INTRuST) Clinical Consortium, and 96 Australian Vietnam War veterans. Differential gene expression analysis was performed in each cohort separately followed by meta-analysis. In the largest cohort, we performed co-expression analysis to identify modules of genes that are associated with PTSD and MDD. We then conducted expression quantitative trait loci (eQTL) analysis and assessed the presence of eQTL interactions involving PTSD and major depressive disorder (MDD). Finally, we utilized PTSD and MDD GWAS summary statistics to identify regions that colocalize with eQTLs. Although not surpassing correction for multiple testing, the most differentially expressed genes in meta-analysis were interleukin-1 beta (IL1B), a pro-inflammatory cytokine previously associated with PTSD, and integrin-linked kinase (ILK), which is highly expressed in brain and can rescue dysregulated hippocampal neurogenesis and memory deficits. Pathway analysis revealed enrichment of toll-like receptor (TLR) and interleukin-1 receptor genes, which are integral to cellular innate immune response. Co-expression analysis identified four modules of genes associated with PTSD, two of which are also associated with MDD, demonstrating common biological pathways underlying the two conditions. Lastly, we identified four genes (UBA7, HLA-F, HSPA1B, and RERE) with high probability of a shared causal eQTL variant with PTSD and/or MDD GWAS variants, thereby providing a potential mechanism by which the GWAS variant contributes to disease risk. In summary, we provide additional evidence for genes and pathways previously reported and identified plausible novel candidates for PTSD. These data provide further insight into genetic factors and pathways involved in PTSD, as well as potential regions of pleiotropy between PTSD and MDD.

Psychological trauma and the genetic overlap between posttraumatic stress disorder and major depressive disorder

BACKGROUND

Posttraumatic stress disorder (PTSD) and major depressive disorder (MDD) are commonly reported co-occurring mental health consequences of psychological trauma exposure. The disorders have high genetic overlap. Trauma is a complex phenotype but research suggests that trauma sensitivity has a heritable basis. We investigated whether sensitivity to trauma in those with MDD reflects a similar genetic component in those with PTSD.

METHODS

Genetic correlations between PTSD and MDD in individuals reporting trauma and MDD in individuals not reporting trauma were estimated, as well as with recurrent MDD and single-episode MDD, using genome-wide association study (GWAS) summary statistics. Genetic correlations were replicated using PTSD data from the Psychiatric Genomics Consortium and the Million Veteran Program. Polygenic risk scores were generated in UK Biobank participants who met the criteria for lifetime MDD (N = 29 471). We investigated whether genetic loading for PTSD was associated with reporting trauma in these individuals.

RESULTS

Genetic loading for PTSD was significantly associated with reporting trauma in individuals with MDD [OR 1.04 (95% CI 1.01-1.07), Empirical-p = 0.02]. PTSD was significantly more genetically correlated with recurrent MDD than with MDD in individuals not reporting trauma (rg differences = ~0.2, p < 0.008). Participants who had experienced recurrent MDD reported significantly higher rates of trauma than participants who had experienced single-episode MDD (χ2 > 166, p < 0.001).

CONCLUSIONS

Our findings point towards the existence of genetic variants associated with trauma sensitivity that might be shared between PTSD and MDD, although replication with better powered GWAS is needed. Our findings corroborate previous research highlighting trauma exposure as a key risk factor for recurrent MDD.

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

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

The factor structure of complex PTSD in combat-exposed Filipino soldiers

The World Health Organization recently released the 11th revision of the International Classification of Diseases with the inclusion of Complex Posttraumatic Stress Disorder (CPTSD). Despite the emerging research examining the symptom structure of CPTSD, to date, none so far have reached consensus on what best represents CPTSD, particularly in soldiers who are exposed regularly in combat situations. This study examined seven latent CPTSD models in a sample of Filipino combat-exposed soldiers (n = 450). Results of confirmatory factor analyses indicated that the correlated 6 factor first-order model (model 2), comprising of re-experiencing, avoidance, persistent sense of current threat, affective dysregulation, negative self-concept, and disturbances in relationships, has the best fit. These findings have implications for understanding CPTSD as a diagnostic entity and provide information on the assessment and crafting of complex trauma interventions, particularly among Filipino combat-exposed soldiers.

Relations between PTSD and depression symptom clusters in samples differentiated by PTSD diagnostic status

Co-occurring posttraumatic stress disorder (PTSD) and depression following traumatic experiences are cumulatively associated with functional impairment. To examine mechanisms for the PTSD-depression comorbidity, we investigated their cluster-level associations. Using data obtained from Amazon's Mechanical Turk platform, 368 trauma-exposed participants were split into two subsamples: those with (n = 163) and without (n = 185) probable PTSD. In both subsamples, confirmatory factor analyses indicated an optimal seven-factor PTSD Hybrid Model. Results of Wald tests of parameter constraints indicated that, in both subsamples, PTSD's dysphoric arousal cluster strongly related to somatic depression compared to all/most other PTSD Hybrid Model clusters. Additionally, in both subsamples, PTSD's negative affect, externalizing behaviors, and anhedonia clusters each strongly related to non-somatic depression compared to PTSD's anxious arousal cluster. Our results indicated that PTSD's dysphoric arousal symptoms mainly accounted for PTSD's shared variance with somatic depression, while the negative alterations in cognitions and mood (NACM)/dysphoria and arousal symptoms (primarily externalizing behaviours) mainly accounted for PTSD's shared variance with non-somatic depression. Our findings have implications for the discussion on PTSD's specific/non-specific clusters tied to diagnostic modifications, for understanding mechanisms underlying PTSD-depression comorbidity, and for the use of transdiagnostic and multi-component treatment protocols for PTSD-depression symptoms.