Polygenic prediction of PTSD trajectories in 9/11 responders

Implications of gene × environment interactions in post-traumatic stress disorder risk and treatment

Exposure to traumatic stress is common in the general population. Variation in the brain's molecular encoding of stress potentially contributes to the heterogeneous clinical outcomes in response to traumatic experiences. For instance, only a minority of those exposed to trauma will develop post-traumatic stress disorder (PTSD). Risk for PTSD is at least partially heritable, with a growing number of genetic factors identified through GWAS. A major limitation of genetic studies is that they capture only the genetic component of risk, whereas PTSD by definition requires an environmental traumatic exposure. Furthermore, the extent, timing, and type of trauma affects susceptibility. Here, we discuss the molecular mechanisms of PTSD risk together with gene × environment interactions, with a focus on how either might inform genetic screening for individuals at high risk for disease, reveal biological mechanisms that might one day yield novel therapeutics, and impact best clinical practices even today. To close, we discuss the interaction of trauma with sex, gender, and race, with a focus on the implications for treatment. Altogether, we suggest that predicting, preventing, and treating PTSD will require integrating both genotypic and environmental information.

Gene expression and epigenetic changes in post-traumatic stress disorder, depression, and anxiety in first responders: A systematic review

OBJECTIVE

Police, firefighters, dispatchers, and emergency medical technicians-collectively known as first responders-are a unique population frequently exposed to chronic, traumatic incidents. This exposure results in a high prevalence of PTSD, depression, and anxiety, posing a substantial public health concern. Genetic predispositions and epigenetic modifications that regulate gene expression are significant contributors to trauma-related pathologies. This systematic review aims to summarize current data on epigenetic and gene expression changes in first responders related to three post-trauma pathologies: PTSD, depression, and anxiety. We also explore genetic pathways across these disorders to identify potential commonalities and therapeutic targets.

METHODS

Following PRISMA guidelines, databases were searched from July to October 2023, yielding 1103 studies, 12 of which met the inclusion criteria (total N = 6943).

RESULTS

Of the included studies, 11 examined PTSD, consistently implicating stress-response genes, such as those in the hypothalamic-pituitary-adrenal axis (e.g., FKBP5, NR3C1), and genes related to inflammation and immune responses. Three studies focused on depression-related genetic biomarkers but reported no significant genome-wide methylation differences between responders with current versus no major depressive disorder (MDD). No studies addressed epigenetic or gene expression changes linked to anxiety.

CONCLUSION

This review identified novel genes and pathways related to trauma as potential targets for future research and pharmacological therapy. It also highlights a significant gap in the literature, emphasizing the need for broader research to investigate the genetic underpinnings of trauma exposure in first responders, aiming to identify relevant pathways and therapeutic targets.

Association of childhood maltreatment and adverse lifetime experiences with post-injury psychopathology: evidence from the China Severe Trauma Cohort

BACKGROUND

Adverse life experiences have been associated with increased susceptibilities to psychopathology in later life. However, their impact on psychological responses following physical trauma remains largely unexplored.

METHODS

Based on the China Severe Trauma Cohort, we conducted a cohort study of 2937 patients who were admitted to the Trauma Medical Center of West China Hospital between June 2020 and August 2023. Adverse life experiences, including childhood maltreatment (5 subtypes, measured by Childhood Trauma Questionnaire-Short Form) and adverse lifetime experiences (17 subtypes, by Life Events Checklist) were assessed. Generalized linear mixed models were used to examine the associations of childhood maltreatment and adverse lifetime experiences with symptoms of psychopathology measured at multiple time-points after the index injury (i.e., at recruitment, 1-, 3-, 6-, and 12-month follow-ups), adjusted for important confounders. We further stratified the analyses by level of genetic predisposition to a given psychological symptom quantified by polygenic risk score (PRS) based on publicly available GWAS summary statistics. Mediation analyses were performed to assess the role of adverse lifetime experiences in connecting childhood maltreatment and post-injury psychopathology.

RESULTS

The mean age of participants was 47.95 years with a predominance of males (61.39%). During the whole follow-up period, the incidence of symptoms of stress-related disorders, anxiety, and depression was 13.86%, 29.89%, and 36.57%, respectively. We observed associations between the cumulative number of those studied adversities and increased risk of post-injury psychopathology, particularly stress-related disorder (odds ratio [OR] = 2.78, 95% confidence interval [CI] 1.87-4.12 for ≥ 2 vs no childhood maltreatment; 2.65 [1.67-4.20] for ≥ 4 vs 0-1 adverse lifetime experiences). By subtype, positive associations were observed for most studied life adversities, with the most pronounced estimates for childhood emotional abuse (ORs = 1.71-2.52) and lifetime life-threatening illness/injury (ORs = 1.87-2.89). We found basically comparable estimates among traumatized individuals with different PRSs for studied psychopathology. Moreover, adverse lifetime experiences may partially (mediation proportion: 22.52-27.48%) explain the associations between various childhood maltreatment and post-injury psychopathology.

CONCLUSIONS

Both childhood maltreatment and adverse lifetime experiences were associated with post-injury psychopathology, irrespective of genetic susceptibility. Such findings highlight the importance of close surveillance and timely psychological interventions for injury patients with adverse life experiences.

Genetic vulnerability and adverse mental health outcomes following mild traumatic brain injury: a meta-analysis of CENTER-TBI and TRACK-TBI cohorts

Background

Post-traumatic stress disorder (PTSD) and depression are common after mild traumatic brain injury (mTBI), but their biological drivers are uncertain. We therefore explored whether polygenic risk scores (PRS) derived for PTSD and major depressive disorder (MDD) are associated with the development of cognate TBI-related phenotypes.

Methods

Meta-analyses were conducted using data from two multicenter, prospective observational cohort studies of patients with mTBI: the CENTER-TBI study (ClinicalTrials.gov ID NCT02210221) in Europe (December 2014-December 2017) and the TRACK-TBI study in the US (March 2014-July 2018). In both cohorts, the most common causes of injury were road traffic accidents and falls. Primary outcomes, specifically probable PTSD and depression, were defined at 6 months post-injury using scores ≥33 on the PTSD Checklist-5 and ≥15 on the Patient Health Questionnaire-9, respectively. We calculated PTSD-PRS and MDD-PRS for patients aged ≥17 years who had a Glasgow Coma Scale score of 13-15 upon hospital arrival and assessed their association with PTSD and depression following TBI. We also evaluated the transferability of the findings in a cohort of African Americans.

Findings

Overall, 11.8% (219/1869) and 6.7% (124/1869) patients were classified as having probable PTSD and depression, respectively. The PTSD-PRS was significantly associated with higher adjusted odds of PTSD in both cohorts, with a pooled odds ratio (OR) of 1.55 [95% confidence interval (CI) 1.30-1.84, p < 0.001, I 2  = 20.8%]. Although the MDD-PRS increased the risk of depression after TBI, it did not reach significance in the individual cohorts. However, in a combined analysis, the risk was significantly elevated with a pooled OR of 1.26 [95% CI 1.03-1.53, p = 0.02, I 2  = 0%]. The addition of PRSs improved the proportion of outcome variance explained in the two study cohorts from 19.5% and 30.3% to 21.6% and 34.0% for PTSD; and from 11.0% and 22.5% to 12.8% and 22.6% for depression. Patients in the highest cognate PRS quintile had increased odds of 3.16 [95% CI 1.80-5.55] and 2.03 [95% CI 1.04-3.94] of developing PTSD or depression compared to the lowest quintile, respectively.

Interpretation

Associations of PRSs with PTSD and depression following TBI are not disorder-specific. However, the overlap between MDD-PRS and depression following TBI is less robust compared to PTSD-PRS and PTSD. PRSs could improve risk prediction, and permit enrichment for interventional trials.

Funding

This study was supported by funding by an FP7 grant from the European Union, Hannelore Kohl Stiftung, Integra LifeSciences Corporation, NeuroTrauma Sciences, US National Institutes of Health, US Department of Defense, National Football League Advisory Board, US Department of Energy, and One Mind.

Rethinking trauma-related psychopathology in the Hierarchical Taxonomy of Psychopathology (HiTOP)

Research on trauma exposure and its consequences has made tremendous progress in elucidating the role of traumatic life events in the development and maintenance of psychopathology as well as in evaluating interventions aimed at addressing the personal and public burden of trauma-related psychopathology. However, there is growing concern that problems with predominant definitions of posttraumatic syndrome (e.g., content coverage and scope, within-category heterogeneity, excessive diagnostic comorbidity) limit further efforts to fully conceptualize trauma-related psychopathology and deliver appropriate, personalized interventions. As demonstrated by an impressive body of research over the past several years, the Hierarchical Taxonomy of Psychopathology (HiTOP) presents a compelling alternative to traditional nosologies in terms of empirically based characterizations of psychopathology phenotypes, with evidence of strong utility for research and clinical applications. However, HiTOP's primary focus on descriptive psychopathology has resulted in an unacceptable gap regarding the conceptualization of trauma-related psychopathology from a dimensional, transdiagnostic perspective. We see an important opportunity to clarify what HiTOP can offer the field of traumatic stress research and articulate a future for trauma-related psychopathology within HiTOP. We argue for disaggregating psychopathology symptoms from their purported causes and, instead, developing a detailed taxonomy of traumatic events alongside an ever-evolving HiTOP model. Doing so will help identify empirically based phenotypes of trauma-related psychopathology that (a) go beyond the traditional PTSD criterion sets and (b) allow for the possibility that different features of traumatic experiences (e.g., type, duration, subjective meaning) may be associated with different symptom sequelae across different psychopathology spectra.

Longitudinal method comparison: modeling polygenic risk for post-traumatic stress disorder over time in individuals of African and European ancestry

Cross-sectional data allow the investigation of how genetics influence health at a single time point, but to understand how the genome impacts phenotype development, one must use repeated measures data. Ignoring the dependency inherent in repeated measures can exacerbate false positives and requires the utilization of methods other than general or generalized linear models. Many methods can accommodate longitudinal data, including the commonly used linear mixed model and generalized estimating equation, as well as the less popular fixed-effects model, cluster-robust standard error adjustment, and aggregate regression. We simulated longitudinal data and applied these five methods alongside naïve linear regression, which ignored the dependency and served as a baseline, to compare their power, false positive rate, estimation accuracy, and precision. The results showed that the naïve linear regression and fixed-effects models incurred high false positive rates when analyzing a predictor that is fixed over time, making them unviable for studying time-invariant genetic effects. The linear mixed models maintained low false positive rates and unbiased estimation. The generalized estimating equation was similar to the former in terms of power and estimation, but it had increased false positives when the sample size was low, as did cluster-robust standard error adjustment. Aggregate regression produced biased estimates when predictor effects varied over time. To show how the method choice affects downstream results, we performed longitudinal analyses in an adolescent cohort of African and European ancestry. We examined how developing post-traumatic stress symptoms were predicted by polygenic risk, traumatic events, exposure to sexual abuse, and income using four approaches-linear mixed models, generalized estimating equations, cluster-robust standard error adjustment, and aggregate regression. While the directions of effect were generally consistent, coefficient magnitudes and statistical significance differed across methods. Our in-depth comparison of longitudinal methods showed that linear mixed models and generalized estimating equations were applicable in most scenarios requiring longitudinal modeling, but no approach produced identical results even if fit to the same data. Since result discrepancies can result from methodological choices, it is crucial that researchers determine their model a priori, refrain from testing multiple approaches to obtain favorable results, and utilize as similar as possible methods when seeking to replicate results.

The interaction between polygenic risk score and trauma affects the likelihood of post-traumatic stress disorder in female victims of sexual assault

OBJECTIVE

Post-traumatic stress disorder (PTSD) is triggered by traumatic events, but genetic vulnerability and a history of childhood trauma may also increase the risk of PTSD onset. Thus, we investigated the interaction between genetic susceptibility according to polygenic risk score (PRS), and traumatic events.

METHODS

We evaluated 68 women with PTSD who had been sexually assaulted and 63 healthy controls with no history of sexual assault. DNA was genotyped using the Infinium Global Screening Array (Illumina, San Diego, CA, USA), and PRS analysis was performed using PRSice. Logistic regression models were also used to determine the interaction between childhood trauma, traumatic life events, and PRS and how they contribute to PTSD risk.

RESULTS

We found a significant association between PRS, childhood trauma (p = 0.03; OR = 1.241), and PTSD. There was also an interaction between PRS, traumatic life events, and childhood trauma, particularly physical and emotional neglect (p = 0.028; OR = 1.010). When examining neglect separately, we found a modest association between emotional neglect and PTSD (p = 0.014; OR = 1.086).

CONCLUSION

Our findings highlight the importance of considering genetic vulnerability and traumatic experiences in understanding the etiology of PTSD.

Genetic Decomposition of the Heritable Component of Reported Childhood Maltreatment

Background

Decades of research have shown that environmental exposures, including self-reports of trauma, are partly heritable. Heritable characteristics may influence exposure to and interpretations of environmental factors. Identifying heritable factors associated with self-reported trauma could improve our understanding of vulnerability to exposure and the interpretation of life events.

Methods

We used genome-wide association study summary statistics of childhood maltreatment, defined as reporting of abuse (emotional, sexual, and physical) and neglect (emotional and physical) (N = 185,414 participants). We calculated genetic correlations (rg) between reported childhood maltreatment and 576 traits to identify phenotypes that might explain the heritability of reported childhood maltreatment, retaining those with |rg| > 0.25. We specified multiple regression models using genomic structural equation modeling to detect residual genetic variance in childhood maltreatment after accounting for genetically correlated traits.

Results

In 2 separate models, the shared genetic component of 12 health and behavioral traits and 7 psychiatric disorders accounted for 59% and 56% of heritability due to common genetic variants (single nucleotide polymorphism-based heritability [h2SNP]) of childhood maltreatment, respectively. Genetic influences on h2SNP of childhood maltreatment were generally accounted for by a shared genetic component across traits. The exceptions to this were general risk tolerance, subjective well-being, posttraumatic stress disorder, and autism spectrum disorder, identified as independent contributors to h2SNP of childhood maltreatment. These 4 traits alone were sufficient to explain 58% of h2SNP of childhood maltreatment.

Conclusions

We identified putative traits that reflect h2SNP of childhood maltreatment. Elucidating the mechanisms underlying these associations may improve trauma prevention and posttraumatic intervention strategies.

Blunted Glucocorticoid Responsiveness to Stress Causes Behavioral and Biological Alterations That Lead to Posttraumatic Stress Disorder Vulnerability

BACKGROUND

Understanding why only a subset of trauma-exposed individuals develop posttraumatic stress disorder is critical for advancing clinical strategies. A few behavioral (deficits in fear extinction) and biological (blunted glucocorticoid levels, small hippocampal size, and rapid-eye-movement sleep [REMS] disturbances) traits have been identified as potential vulnerability factors. However, whether and to what extent these traits are interrelated and whether one of them could causally engender the others are not known.

METHODS

In a genetically selected rat model of reduced corticosterone responsiveness to stress, we explored posttraumatic stress disorder-related biobehavioral traits using ex vivo magnetic resonance imaging, cued fear conditioning, and polysomnographic recordings combined with in vivo photometric measurements.

RESULTS

We showed that genetic selection for blunted glucocorticoid responsiveness led to a correlated multitrait response, including impaired fear extinction (observed in males but not in females), small hippocampal volume, and REMS disturbances, supporting their interrelatedness. Fear extinction deficits and concomitant disruptions in REMS could be normalized through postextinction corticosterone administration, causally implicating glucocorticoid deficiency in two core posttraumatic stress disorder-related risk factors and manifestations. Furthermore, reduced REMS was accompanied by higher norepinephrine levels in the hippocampal dentate gyrus that were also reversed by postextinction corticosterone treatment.

CONCLUSIONS

Our results indicate a predominant role for glucocorticoid deficiency over the contribution of reduced hippocampal volume in engendering both REMS alterations and associated deficits in fear extinction consolidation, and they causally implicate blunted glucocorticoids in sustaining neurophysiological disturbances that lead to fear extinction deficits.

Candidate biomarkers in psychiatric disorders: state of the field

The field of psychiatry is hampered by a lack of robust, reliable and valid biomarkers that can aid in objectively diagnosing patients and providing individualized treatment recommendations. Here we review and critically evaluate the evidence for the most promising biomarkers in the psychiatric neuroscience literature for autism spectrum disorder, schizophrenia, anxiety disorders and post-traumatic stress disorder, major depression and bipolar disorder, and substance use disorders. Candidate biomarkers reviewed include various neuroimaging, genetic, molecular and peripheral assays, for the purposes of determining susceptibility or presence of illness, and predicting treatment response or safety. This review highlights a critical gap in the biomarker validation process. An enormous societal investment over the past 50 years has identified numerous candidate biomarkers. However, to date, the overwhelming majority of these measures have not been proven sufficiently reliable, valid and useful to be adopted clinically. It is time to consider whether strategic investments might break this impasse, focusing on a limited number of promising candidates to advance through a process of definitive testing for a specific indication. Some promising candidates for definitive testing include the N170 signal, an event-related brain potential measured using electroencephalography, for subgroup identification within autism spectrum disorder; striatal resting-state functional magnetic resonance imaging (fMRI) measures, such as the striatal connectivity index (SCI) and the functional striatal abnormalities (FSA) index, for prediction of treatment response in schizophrenia; error-related negativity (ERN), an electrophysiological index, for prediction of first onset of generalized anxiety disorder, and resting-state and structural brain connectomic measures for prediction of treatment response in social anxiety disorder. Alternate forms of classification may be useful for conceptualizing and testing potential biomarkers. Collaborative efforts allowing the inclusion of biosystems beyond genetics and neuroimaging are needed, and online remote acquisition of selected measures in a naturalistic setting using mobile health tools may significantly advance the field. Setting specific benchmarks for well-defined target application, along with development of appropriate funding and partnership mechanisms, would also be crucial. Finally, it should never be forgotten that, for a biomarker to be actionable, it will need to be clinically predictive at the individual level and viable in clinical settings.

Association of polygenic risk scores, traumatic life events and coping strategies with war-related PTSD diagnosis and symptom severity in the South Eastern Europe (SEE)-PTSD cohort

OBJECTIVES

Posttraumatic stress disorder (PTSD) is triggered by extremely stressful environmental events and characterized by high emotional distress, re-experiencing of trauma, avoidance and hypervigilance. The present study uses polygenic risk scores (PRS) derived from the UK Biobank (UKBB) mega-cohort analysis as part of the PGC PTSD GWAS effort to determine the heritable basis of PTSD in the South Eastern Europe (SEE)-PTSD cohort. We further analyzed the relation between PRS and additional disease-related variables, such as number and intensity of life events, coping, sex and age at war on PTSD and CAPS as outcome variables.

METHODS

Association of PRS, number and intensity of life events, coping, sex and age on PTSD were calculated using logistic regression in a total of 321 subjects with current and remitted PTSD and 337 controls previously subjected to traumatic events but not having PTSD. In addition, PRS and other disease-related variables were tested for association with PTSD symptom severity, measured by the Clinician Administrated PTSD Scale (CAPS) by liner regression. To assess the relationship between the main outcomes PTSD diagnosis and symptom severity, each of the examined variables was adjusted for all other PTSD related variables.

RESULTS

The categorical analysis showed significant polygenic risk in patients with remitted PTSD and the total sample, whereas no effects were found on symptom severity. Intensity of life events as well as the individual coping style were significantly associated with PTSD diagnosis in both current and remitted cases. The dimensional analyses showed as association of war-related frequency of trauma with symptom severity, whereas the intensity of trauma yielded significant results independently of trauma timing in current PTSD.

CONCLUSIONS

The present PRS application in the SEE-PTSD cohort confirms modest but significant polygenic risk for PTSD diagnosis. Environmental factors, mainly the intensity of traumatic life events and negative coping strategies, yielded associations with PTSD both categorically and dimensionally with more significant p-values. This suggests that, at least in the present cohort of war-related trauma, the association of environmental factors and current individual coping strategies with PTSD psychopathology was stronger than the polygenic risk.

Laboratory models of post-traumatic stress disorder: The elusive bridge to translation

Post-traumatic stress disorder (PTSD) is a debilitating mental illness composed of a heterogeneous collection of symptom clusters. The unique nature of PTSD as arising from a precipitating traumatic event helps simplify cross-species translational research modeling the neurobehavioral effects of stress and fear. However, the neurobiological progress on these complex neural circuits informed by animal models has yet to produce novel, evidence-based clinical treatment for PTSD. Here, we provide a comprehensive overview of popular laboratory models of PTSD and provide concrete ideas for improving the validity and clinical translational value of basic research efforts in humans. We detail modifications to simplified animal paradigms to account for myriad cognitive factors affected in PTSD, which may contribute to abnormalities in regulating fear. We further describe new avenues for integrating different areas of psychological research underserved by animal models of PTSD. This includes incorporating emerging trends in the cognitive neuroscience of episodic memory, emotion regulation, social-emotional processes, and PTSD subtyping to provide a more comprehensive recapitulation of the human experience to trauma in laboratory research.

Neurobiological mechanisms underlying delayed expression of posttraumatic stress disorder: A scoping review

BACKGROUND

The capacity of posttraumatic stress disorder (PTSD) to occur with delayed onset has been documented in several systematic reviews and meta-analyses. Neurobiological models of PTSD may provide insight into the mechanisms underlying the progressive increase in PTSD symptoms over time as well as into occasional occurrences of long-delayed PTSD with few prodromal symptoms.

AIM

To obtain an overview of key concepts explaining and types of evidence supporting neurobiological underpinnings of delayed PTSD.

METHODS

A scoping review of studies reporting neurobiological findings relevant to delayed PTSD was performed, which included 38 studies in the qualitative synthesis.

RESULTS

Neurobiological mechanisms underlying PTSD symptoms, onset, and course involve several interconnected systems. Neural mechanisms involve the neurocircuitry of fear, comprising several structures, such as the hippocampus, amygdala, and prefrontal cortex, that are amenable to time-dependent increases in activity through sensitization and kindling. Neural network models explain generalization of the fear response. Neuroendocrine mechanisms consist of autonomic nervous system and hypothalamic-pituitary-adrenocortical axis responses, both of which may be involved in sensitization to stress. Neuroinflammatory mechanisms are characterized by immune activation, which is sometimes due to the effects of traumatic brain injury. Finally, neurobehavioral/contextual mechanisms involve the effects of intervening stressors and mental and physical disorder comorbidities, and these may be particularly relevant in cases of long-delayed PTSD.

CONCLUSION

Thus, delayed PTSD may result from multiple underlying neurobiological mechanisms that may influence the likelihood of developing prodromal symptoms preceding the onset of full-blown PTSD.

Shorter Telomeres Related to Posttraumatic Stress Disorder Re-experiencing Symptoms in Sexually Assaulted Civilian Women

Telomeres are short tandem repeats of "TTAGGG" that protect the chromosome ends from deterioration or fusion of chromosomes. Their repeat length shortens with cell division acting as a biomarker of cellular aging. Traumatic stress events during adulthood or childhood have been associated with posttraumatic stress disorder (PTSD) and short leukocyte telomere length (LTL). This study investigated whether LTL was associated with PTSD in a Brazilian sample of sexually assaulted civilian women at two time points: baseline and 1-year follow-up. At baseline, we assessed 64 women with PTSD following sexual assault (cases) and 60 women with no previous history of sexual trauma or mental disorders (healthy controls - HC). At follow-up visit, 13 persistent PTSD cases, 11 HCs, and 11 PTSD remitters patients were evaluated. PTSD diagnosis and severity were assessed using Mini International Neuropsychiatric Interview (Diagnostic and Statistical Manual of Mental Disorders III/IV criteria) and Clinician-Administered PTSD Scale for DSM-5 (CAPS-5), respectively. LTL was measured using multiplex real-time polymerase chain reaction (PCR). In the baseline analysis, we observed that LTL was associated with re-experiencing symptoms (B = -0.16; confidence interval (CI) 95% = -0.027--0.005; Bonferroni-adjusted p-value = 0.02), but no association was observed between other PTSD symptoms and LTL. In the longitudinal analysis, telomere shortening was no longer observed in patients with PTSD and PTSD remitters. In conclusion, our findings indicate that shorter baseline LTL is associated with early stage of PTSD re-experiencing symptoms in recently sexually assaulted women.

From genetics to systems biology of stress-related mental disorders

Many individuals will be exposed to some form of traumatic stress in their lifetime which, in turn, increases the likelihood of developing stress-related disorders such as post-traumatic stress disorder (PTSD), major depressive disorder (MDD) and anxiety disorders (ANX). The development of these disorders is also influenced by genetics and have heritability estimates ranging between ∼30 and 70%. In this review, we provide an overview of the findings of genome-wide association studies for PTSD, depression and ANX, and we observe a clear genetic overlap between these three diagnostic categories. We go on to highlight the results from transcriptomic and epigenomic studies, and, given the multifactorial nature of stress-related disorders, we provide an overview of the gene-environment studies that have been conducted to date. Finally, we discuss systems biology approaches that are now seeing wider utility in determining a more holistic view of these complex disorders.

Polygenic risk scoring to assess genetic overlap and protective factors influencing posttraumatic stress, depression, and chronic pain after motor vehicle collision trauma

Posttraumatic stress (PTS), depressive symptoms (DS), and musculoskeletal pain (MSP) are common sequelae of trauma exposure. Although these adverse posttraumatic neuropsychiatric sequelae (APNS) are often studied separately, clinical comorbidity is high. In a cohort of European American motor vehicle collision (MVC) trauma survivors (n = 781), substantial PTS (≥33, IES-R), DS (≥26, CES-D), and MSP (≥4, 0-10 NRS) were identified via a 6-month survey. Genetic risk was estimated using polygenic risk scores (PRSs) calculated from the largest available GWAS datasets of PTSD, MDD, and back pain. We then assessed comorbidity and genetic risk influence for developing chronic PTS, DS, and MSP after MVC. Secondary analyses explored whether common social determinants of health ameliorate genetic vulnerability. We found that 6 months after MVC, nearly half 357/781 (46%) of the participants had substantial PTS, DS, and/or MSP, and overlap was common (PTS + MSP (23%), DS + MSP (18%), PTS + DS (12%)). Genetic risk predicted post-MVC outcomes. PTSD-PRSs predicted PTS and DS (R² = 2.21% and 2.77%, p_adj < 0.01), MDD-PRSs predicted DS and MSP (R² = 1.89%, p_adj < 0.01) and 0.79%, p_adj < 0.05), and back pain-PRS predicted MSP (R² = 1.49%, p_adj < 0.01). Individuals in the highest quintile of PTSD-PRSs had 2.8 and 3.5 times the odds of developing PTS and DS vs. the lowest quintile (95% CI = 1.39-5.75 and 1.58-7.76). Among these high-risk individuals, those living in non-disadvantaged neighborhoods and with college education had 47% (p = 0.048) and 52% (p = 0.04) less risk of developing PTS, and those with high social support had 60% (p = 0.008) less risk of developing DS. Overall, genetic factors influence the risk of APNS after MVC, genetic risk of distinct APNS are overlapping, and specific social determinants greatly augment genetic risk of APNS development after MVC.

A Genome-Wide Association Study and Polygenic Risk Score Analysis of Posttraumatic Stress Disorder and Metabolic Syndrome in a South African Population

Posttraumatic stress disorder (PTSD) is a trauma-related disorder that frequently co-occurs with metabolic syndrome (MetS). MetS is characterized by obesity, dyslipidemia, and insulin resistance. To provide insight into these co-morbidities, we performed a genome-wide association study (GWAS) meta-analysis to identify genetic variants associated with PTSD, and determined if PTSD polygenic risk scores (PRS) could predict PTSD and MetS in a South African mixed-ancestry sample. The GWAS meta-analysis of PTSD participants (n = 260) and controls (n = 343) revealed no SNPs of genome-wide significance. However, several independent loci, as well as five SNPs in the PARK2 gene, were suggestively associated with PTSD (p < 5 × 10-6). PTSD-PRS was associated with PTSD diagnosis (Nagelkerke's pseudo R 2 = 0.0131, p = 0.00786), PTSD symptom severity [as measured by CAPS-5 total score (R 2 = 0.00856, p = 0.0367) and PCL-5 score (R 2 = 0.00737, p = 0.0353)], and MetS (Nagelkerke's pseudo R 2 = 0.00969, p = 0.0217). These findings suggest an association between PTSD and PARK2, corresponding with results from the largest PTSD-GWAS conducted to date. PRS analysis suggests that genetic variants associated with PTSD are also involved in the development of MetS. Overall, the results contribute to a broader goal of increasing diversity in psychiatric genetics.

Mapping the transcriptomics landscape of post-traumatic stress disorder symptom dimensions in World Trade Center responders

Gene expression has provided promising insights into the pathophysiology of post-traumatic stress disorder (PTSD); however, specific regulatory transcriptomic mechanisms remain unknown. The present study addressed this limitation by performing transcriptome-wide RNA-Seq of whole-blood samples from 226 World Trade Center responders. The investigation focused on differential expression (DE) at the gene, isoform, and for the first time, alternative splicing (AS) levels associated with the symptoms of PTSD: total burden, re-experiencing, avoidance, numbing, and hyperarousal subdimensions. These symptoms were associated with 76, 1, 48, 15, and 49 DE genes, respectively (FDR < 0.05). Moreover, they were associated with 103, 11, 0, 43, and 32 AS events. Avoidance differed the most from other dimensions with respect to DE genes and AS events. Gene set enrichment analysis (GSEA) identified pathways involved in inflammatory and metabolic processes, which may have implications in the treatment of PTSD. Overall, the findings shed a novel light on the wide range of transcriptomic alterations associated with PTSD at the gene and AS levels. The results of DE analysis associated with PTSD subdimensions highlights the importance of studying PTSD symptom heterogeneity.

Dissecting the heterogeneity of posttraumatic stress disorder: differences in polygenic risk, stress exposures, and course of PTSD subtypes

BACKGROUND

Definition of disorder subtypes may facilitate precision treatment for posttraumatic stress disorder (PTSD). We aimed to identify PTSD subtypes and evaluate their associations with genetic risk factors, types of stress exposures, comorbidity, and course of PTSD.

METHODS

Data came from a prospective study of three U.S. Army Brigade Combat Teams that deployed to Afghanistan in 2012. Soldiers with probable PTSD (PTSD Checklist for Diagnostic and Statistical Manual of Mental Disorders-Fifth Edition ≥31) at three months postdeployment comprised the sample (N = 423) for latent profile analysis using Gaussian mixture modeling and PTSD symptom ratings as indicators. PTSD profiles were compared on polygenic risk scores (derived from external genomewide association study summary statistics), experiences during deployment, comorbidity at three months postdeployment, and persistence of PTSD at nine months postdeployment.

RESULTS

Latent profile analysis revealed profiles characterized by prominent intrusions, avoidance, and hyperarousal (threat-reactivity profile; n = 129), anhedonia and negative affect (dysphoric profile; n = 195), and high levels of all PTSD symptoms (high-symptom profile; n = 99). The threat-reactivity profile had the most combat exposure and the least comorbidity. The dysphoric profile had the highest polygenic risk for major depression, and more personal life stress and co-occurring major depression than the threat-reactivity profile. The high-symptom profile had the highest rates of concurrent mental disorders and persistence of PTSD.

CONCLUSIONS

Genetic and trauma-related factors likely contribute to PTSD heterogeneity, which can be parsed into subtypes that differ in symptom expression, comorbidity, and course. Future studies should evaluate whether PTSD typology modifies treatment response and should clarify distinctions between the dysphoric profile and depressive disorders.