The Implication of Combat Stress and PTSD Trajectories in Metabolic Syndrome and Elevated C-Reactive Protein Levels: A Longitudinal Study

Stress-induced NLRP3 inflammasome activation and myelin alterations in the hippocampus of PTSD rats

Inflammatory and myelin changes may contribute to the pathophysiology of post-traumatic stress disorder (PTSD). The NOD-like receptor (NLR) family, pyrin domain-containing protein 3 (NLRP3), a brain inflammasome, is activated in the hippocampus of mice with PTSD. In other psychiatric disorders, NLRP3 expression has been associated with axonal myelination and demyelination. However, the association between NLRP3 and myelin in rats with PTSD remains unclear. Therefore, this study aims to investigate the relationship between the NLRP3 inflammasome and myelin in the hippocampus of rats with PTSD. A rat model of post-traumatic stress disorder was established using the single-prolonged stress (SPS) approach. Hippocampal tissues were collected for the detection of NLRP3 inflammasome-associated proteins and myelin basic protein at 3, 7, and 14 days after SPS. To further explore the relationship between NLRP3 and myelin, the NLRP3-specific inhibitor MCC950 was administered intraperitoneally to rats starting 72 h before SPS, and then alterations in NLRP3 inflammasome-associated proteins and myelin were observed in the PTSD and control groups. We found that NLRP3 and downstream related proteins were activated in the hippocampus of rats 3 days after SPS, and the myelin content in the hippocampus increased after SPS stress. MCC950 reduced the expression of NLRP3-related pathway proteins, improved anxiety behaviour and spatial learning memory impairment, and inhibited the increase in myelin content in the hippocampal region of rats after SPS. In conclusion the study indicates that NLRP3 has a significant role in the hippocampal region of rats with PTSD. Inhibition of the NLRP3 inflammasome could be a potential target for treating PTSD.

Sex-specific immune mechanisms in PTSD symptomatology and risk: A translational overview and perspectives

Altered immune function in patients with posttraumatic stress disorder (PTSD) may play a role in the disorder pathophysiology and onset. Women are more likely to develop PTSD, suggesting potential sex-specific inflammatory mechanisms underlying the dichotomous prevalence and risk of PTSD in men and women. In this review we examine the available literature to better assess the state of knowledge in the field. In humans, increased systemic inflammation is found in both men and women with PTSD, but seems to be at a greater extend in women. Despite the existence of few clinical studies taking account of sex as a factor in the observed immune changes in PTSD, challenges in the study of sex-specific immune function in humans include: controlling for confounding variates such as the type of trauma and the ethnicity; and limited methodologies available to study central nervous system (CNS)-relevant changes. Thus, preclinical studies are a valuable tool to provide us with key insights on sex-specific peripheral and CNS immune mechanisms underlying PTSD. Available preclinical studies reported increased systemic and CNS inflammation, as well as elevated trafficking of monocytes from the periphery to the brain in both male and female rodents. To date, psychological trauma-induced inflammation is more robust in female vs male rodents. Limitations of preclinical studies include animal models hardly applicable to female rodents, and hormonal changes across estrus phases that may affect immune function. The present review: (1) highlights the key findings from both human and animal studies, (2) provides guidance to address limitations; and (3) discusses the gap of knowledge on the complex intertwined interaction between the brain, neurovascular, and systemic units.

Potential peripheral biomarkers associated with the emergence and presence of posttraumatic stress disorder symptomatology: A systematic review

BACKGROUND

Evidence suggests posttraumatic stress disorder (PTSD) involves an interplay between psychological manifestations and biological systems. Biological markers of PTSD could assist in identifying individuals with underlying dysregulation and increased risk; however, accurate and reliable biomarkers are yet to be identified.

METHODS

A systematic review following the PRISMA guidelines was conducted. Databases included EMBASE, MEDLINE, and Cochrane Central. Studies from a comprehensive 2015 review (Schmidt et al., 2015) and English language papers published subsequently (between 2014 and May 2022) were included. Forty-eight studies were eligible.

RESULTS

Alterations in neuroendocrine and immune markers were most commonly associated with PTSD symptoms. Evidence indicates PTSD symptoms are associated with hypothalamic-pituitary-adrenal axis dysfunction as represented by low basal cortisol, a dysregulated immune system, characterized by an elevated pro-inflammatory state, and metabolic dysfunction. However, a considerable number of studies neglected to measure sex or prior trauma, which have the potential to affect the biological outcomes of posttraumatic stress symptoms. Mixed findings are indicative of the complexity and heterogeneity of PTSD and suggest the relationship between allostatic load, biological markers, and PTSD remain largely undefined.

CONCLUSIONS

In addition to prospective research design and long-term follow up, it is imperative future research includes covariates sex, prior trauma, and adverse childhood experiences. Future research should include exploration of biological correlates specific to PTSD symptom domains to determine whether underlying processes differ with symptom expression, in addition to subclinical presentation of posttraumatic stress symptoms, which would allow for greater understanding of biomarkers associated with disorder risk and assist in untangling directionality.

Acupuncture for military veterans with posttraumatic stress disorder and related symptoms after combat exposure: Protocol for a scoping review of clinical studies

Posttraumatic stress disorder is caused by traumatic events such as death, serious injury, and sexual violence. Military personnel and veterans are at high risk for posttraumatic stress disorder. Conventional posttraumatic stress disorder treatments have certain limitations. Complementary and integrative medicine treatments, especially acupuncture, are potential novel first-line treatments that may overcome these limitations. We aim to investigate the current status of the available clinical evidence related to acupuncture treatment for posttraumatic stress disorder in war veterans. We will follow the scoping review process as previously described. The study question is as follows: "Which types of clinical research designs, study types, study durations, adverse events, and clinical outcomes have been reported regarding acupuncture therapy for posttraumatic stress disorder in military veterans?" We will perform a comprehensive search of Medline, Excerpta Medica dataBASE, Cochrane Central Register of Controlled Trials, Web of Science, Scopus databases, Allied and Complementary Medicine Database, Cumulative Index to Nursing and Allied Health Literature, and PsycArticles databases, as well as Chinese, Korean, and Japanese databases, from inception to June 2022. Data from the included studies will be collected and descriptively analyzed in relation to our research question. The extracted data will be collated, synthesized, and summarized according to the analytical framework of a scoping review. The protocol of this study adheres to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews to ensure the clarity and completeness of our reporting in all phases of this scoping review (Protocol registration: https://osf.io/t723f/). The findings of this scoping review will provide fundamental data that will help researchers identify appropriate research questions and design further studies on the use of acupuncture for PTSD management in military veterans. These results will be helpful for developing disaster site-specific research protocols for future clinical trials on this topic.

PTSD, Immune System, and Inflammation

Posttraumatic stress disorder (PTSD) is a severe trauma and stress-related disorder associated with different somatic comorbidities, especially cardiovascular and metabolic disorders, and with chronic low-grade inflammation. Altered balance of the hypothalamic-pituitary-adrenal (HPA) axis, cytokines and chemokines, C-reactive protein, oxidative stress markers, kynurenine pathways, and gut microbiota might be involved in the alterations of certain brain regions regulating fear conditioning and memory processes, that are all altered in PTSD. In addition to the HPA axis, the gut microbiota maintains the balance and interaction of the immune, CNS, and endocrine pathways forming the gut-brain axis. Disbalance in the HPA axis, gut-brain axis, oxidative stress pathways and kynurenine pathways, altered immune signaling and disrupted homeostasis, as well as the association of the PTSD with the inflammation and disrupted cognition support the search for novel strategies for treatment of PTSD. Besides potential anti-inflammatory treatment, dietary interventions or the use of beneficial bacteria, such as probiotics, can potentially improve the composition and the function of the bacterial community in the gut. Therefore, bacterial supplements and controlled dietary changes, with exercise, might have beneficial effects on the psychological and cognitive functions in patients with PTSD. These new treatments should be aimed to attenuate inflammatory processes and consequently to reduce PTSD symptoms but also to improve cognition and reduce cardio-metabolic disorders associated so frequently with PTSD.

The role of the immune system in posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) develops in a subset of individuals upon exposure to traumatic stress. In addition to well-defined psychological and behavioral symptoms, some individuals with PTSD also exhibit elevated concentrations of inflammatory markers, including C-reactive protein, interleukin-6, and tumor necrosis factor-α. Moreover, PTSD is often co-morbid with immune-related conditions, such as cardiometabolic and autoimmune disorders. Numerous factors, including lifetime trauma burden, biological sex, genetic background, metabolic conditions, and gut microbiota, may contribute to inflammation in PTSD. Importantly, inflammation can influence neural circuits and neurotransmitter signaling in regions of the brain relevant to fear, anxiety, and emotion regulation. Given the link between PTSD and the immune system, current studies are underway to evaluate the efficacy of anti-inflammatory treatments in those with PTSD. Understanding the complex interactions between PTSD and the immune system is essential for future discovery of diagnostic and therapeutic tools.

Posttraumatic Stress Disorder Mediates the Association between Traumatic World Trade Center Dust Cloud Exposure and Ongoing Systemic Inflammation in Community Members

Exposure to World Trade Center (WTC) dust/fumes and traumas on 11 September 2001 has been reported as a risk factor for post-traumatic stress disorder (PTSD) and other mental/physical health symptoms in WTC-affected populations. Increased systemic inflammation and oxidative stress from the exposure and subsequent illnesses have been proposed as contributors to the underlying biological processes. Many blood-based biomarkers of systemic inflammation, including C-reactive protein (CRP), are useful for non-invasive diagnostic and monitoring of disease process, and also potential targets for therapeutic interventions. Twenty years after 9/11, however, the relationships between WTC exposure, chronic PTSD, and systemic inflammation are only beginning to be systematically investigated in the WTC-affected civilian population despite the fact that symptoms of PTSD and systemic inflammation are still common and persistent. This paper aims to address this knowledge gap, using enrollees of the WTC Environmental Health Center (EHC), a federally designated treatment and surveillance program for community members (WTC Survivors) exposed to the 9/11 terrorist attack. We conducted a mediation analysis to investigate the association between acute WTC dust cloud traumatic exposure (WDCTE) on 9/11, chronic PTSD symptoms, and levels of systemic inflammation. The data indicate that the chronic PTSD symptoms and some specific symptom clusters of PTSD significantly mediate the WDCTE on systemic inflammation, as reflected by the CRP levels. As both chronic PTSD and systemic inflammation are long-term risk factors for neurodegeneration and cognitive decline, further research on the implications of this finding is warranted.

How does PTSD treatment affect cardiovascular, diabetes and metabolic disease risk factors and outcomes? A systematic review

OBJECTIVE

Prior research indicates PTSD is associated with cardiovascular and metabolic disease. A number of different treatments for PTSD can be effective in reducing PTSD symptoms. The aim of this study is to systematically review studies which determine whether treatment for PTSD is associated with better cardiovascular and metabolic outcomes.

METHOD

Five different databases were searched in a systematic manner, and 11 relevant studies were recovered and analyzed.

FINDINGS

Treatments associated with PTSD improvement and found to be effective in improving cardiovascular or metabolic outcomes among individuals with PTSD include cognitive behavioral therapy (heart rate variability and blood pressure), prolonged exposure (heart rate and heart rate variability) and SSRIs (blood pressure).

CONCLUSIONS

Multiple PTSD treatment modalities were associated with improved cardiovascular health and reduced risk of cardiovascular-related mortality. Given the small sample sizes, lack of follow-up studies and the extensive use of military populations in studies on PTSD and chronic diseases, these results should be interpreted with caution. More studies are needed that assess and verify whether PTSD treatments mitigate the risk for metabolic, diabetic and cardiovascular disease.

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.

Depression and Elevated Inflammation Among Chinese Older Adults: Eight Years After the 2003 SARS Epidemic

BACKGROUND AND OBJECTIVES

This study examined associations between exposure to the 2003 Severe Acute Respiratory Syndrome (SARS) epidemic and Chinese older adults' depression and inflammation 8 years after the crisis. Further, this study investigated the buffering effects of perceived social support and social participation.

RESEARCH DESIGN AND METHODS

Data were drawn from the 2011 China Health and Retirement Longitudinal Survey, including N = 4,341 Chinese adults aged 60 years and older. For the survey, local officials identified whether the 2003 SARS outbreak was one of the major disasters in the history of their communities. Depression was assessed by the Center for Epidemiological Studies-Depression scale and inflammation was measured by C-reactive protein (CRP) collected from participants via venous blood draws.

RESULTS

Results from multilevel logistic regression models revealed that Chinese older adults living in communities exposed to SARS were more likely to have elevated CRP compared to those not living in such communities. Moreover, community SARS exposure was associated with greater risks of depression for Chinese older adults who had no perceived social support. Among Chinese older adults who had low levels of social participation, community SARS exposure was more strongly related to elevated CRP.

DISCUSSION AND IMPLICATIONS

Findings suggest community-level exposure to the SARS epidemic had enduring consequences for Chinese older adults' health. However, active social participation and supportive social ties provided important resources that may buffer against negative effects of exposure to the SARS epidemic.

Hospital admissions for non-communicable disease in the UK military and associations with alcohol use and mental health: a data linkage study

BACKGROUND

Since the recent conflicts in Iraq and Afghanistan, the short-term focus of military healthcare research has been on the consequences of deployment for mental health and on those wounded or injured in combat. Now that these conflicts have ended for the UK Armed Forces, it is important to consider the longer term physical and mental health consequences, and just as importantly, the links between these. The aims of this study were to determine the most common physical conditions requiring a hospital admission in UK military personnel and whether they were more common in personnel with a mental health condition, smokers, and/or those misusing alcohol compared to those without.

METHODS

Data linkage of a prospective UK military cohort study to electronic admitted patient care records for England, Wales and Scotland. Nine thousand nine hundred ninety military personnel completed phase 2 of a military cohort study (56% response rate, data collected from 2007 to 2009), with analyses restricted to 86% of whom provided consent for linkage to healthcare records (n = 8602). Ninety percent were male and the mean age at phase 2 was 36 years. The outcome was physical non communicable diseases (NCDs) requiring a hospital admission which occurred after phase 2 of the cohort when the mental health, smoking and alcohol use exposure variables had been assessed until the end of March 2014.

RESULTS

The most common NCDs requiring a hospital admission were gastrointestinal disorders 5.62% (95% Confidence Intervals (CI) 5.04, 6.19) and joint disorders 5.60% (95% CI 5.02, 6.18). Number of NCDs requiring a hospital admission was significantly higher in those with a common mental disorder (Hazard ratio (HR) 1.40 (95% CI 1.16-1.68), post-traumatic stress disorder (HR 1.78 (95% CI 1.32-2.40)) and in current smokers (HR 1.35 (95% CI 1.12-1.64) compared to those without the disorder, and non-smokers, respectively.

CONCLUSIONS

Military personnel with a mental health problem are more likely to have an inpatient hospital admission for NCDs compared to those without, evidencing the clear links between physical and mental health in this population.

Posttraumatic Stress Disorder and Inflammation: Untangling Issues of Bidirectionality

Posttraumatic stress disorder (PTSD) has increasingly been linked to heightened systemic inflammation. It matters whether this association is causal (and either bidirectional or unidirectional) or correlational. Investigators have hypothesized that chronic systemic low-grade inflammation may contribute to greater risk of developing PTSD after experiencing trauma and/or serve as a mechanism linking PTSD to adverse physical health outcomes. However, if the PTSD-inflammation relation is correlational, it may not warrant further research aimed at understanding inflammation as a PTSD risk factor or as a pathway linking PTSD with poor health. In this review, we first assess the longitudinal evidence related to PTSD and inflammation to understand more clearly the directionality and causal nature of this relation. Overall, few longitudinal studies rigorously assess the direction of the PTSD-inflammation relation. Some of the evidence indicates that elevated inflammation assessed pretrauma or in the acute aftermath of trauma increases risk for developing PTSD. Fewer studies evaluate the influence of PTSD on subsequent inflammation levels, and findings are mixed. Sample characteristics and study designs, and also the type of inflammation-related measure, vary widely across studies. Based on current evidence, we then recommend several statistical and study design approaches that may help untangle issues of bidirectionality and aid in determining the direction of causality between PTSD and inflammation. Last, we conclude with future research directions and consider potential implications for interventions or treatment approaches based on this growing body of literature.

The relationship among psychopathology, religiosity, and nicotine dependence in Croatian war veterans with posttraumatic stress disorder

Aim

To examine relationships among combat exposure, posttraumatic stress disorder (PTSD) symptoms, depression, suicidality, nicotine dependence, and religiosity in Croatian veterans.

Methods

This cross-sectional study used Combat Exposure Scale (CES) to quantify the stressor severity, PTSD Checklist 5 (PCL) to quantify PTSD severity, Duke University Religion Index to quantify religiosity, Montgomery Asberg (MADRS) and Hamilton Depression (HAM-D) rating scales to measure depression/suicidality, and Fagerstrom Test for Nicotine Dependence to assess nicotine dependence. Zero-order correlations, cluster analysis, multivariate regression, and mediation models were used for data analysis.

Results

Of 69 patients included, 71% met “high religiosity” criteria and 29% had moderate/high nicotine dependence. PTSD was severe (median PCL 71), depression was mild/moderate (median MADRS 19, HAM-D 14), while suicidality was mild. A subset of patients was identified with more severe PTSD/depression/suicidality and nicotine dependence (all P < 0.001). Two “chains” of direct and indirect independent associations were detected. Higher CES was associated with higher level of re-experiencing and, through re-experiencing, with higher negativity and hyperarousal. It also showed “downstream” division into two arms, one including a direct and indirect association with higher depression and lower probability of high religiosity, and the other including associations with higher suicidality and lower probability of high nicotine dependence.

Conclusions

Psychopathology, religiosity, and nicotine dependence are intertwined in a complex way not detectable by simple direct associations. Heavy smoking might be a marker of severe PTSD psychopathology, while spirituality might be targeted in attempts of its alleviation.

Oxford Centre for Evidence-based Medicine level of evidence: 3

Posttraumatic stress disorder as a diagnostic entity – clinical perspectives

Throughout history the consequences of psychological trauma and characteristic symptoms have involved clinical presentations that have had different names. Since the inclusion of the category of Posttraumatic Stress Disorder (PTSD) in the third edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-III) with the symptomatic triad of re-experiencing the traumatic event, avoidance behaviors, and hypervigilance, this entity has been a source of controversy. Indeed, some authors have denied its existence, even considering it a diagnostic invention. In this article we review, from the clinician's perspective, historical aspects as well as the development of the nosological classifications and the contributions from the neurosciences that allow the consideration of the full validity of this diagnosis as a form of psychobiological reaction to psychological trauma.

Mast Cell Activation in Brain Injury, Stress, and Post-traumatic Stress Disorder and Alzheimer's Disease Pathogenesis

Mast cells are localized throughout the body and mediate allergic, immune, and inflammatory reactions. They are heterogeneous, tissue-resident, long-lived, and granulated cells. Mast cells increase their numbers in specific site in the body by proliferation, increased recruitment, increased survival, and increased rate of maturation from its progenitors. Mast cells are implicated in brain injuries, neuropsychiatric disorders, stress, neuroinflammation, and neurodegeneration. Brain mast cells are the first responders before microglia in the brain injuries since mast cells can release prestored mediators. Mast cells also can detect amyloid plaque formation during Alzheimer's disease (AD) pathogenesis. Stress conditions activate mast cells to release prestored and newly synthesized inflammatory mediators and induce increased blood-brain barrier permeability, recruitment of immune and inflammatory cells into the brain and neuroinflammation. Stress induces the release of corticotropin-releasing hormone (CRH) from paraventricular nucleus of hypothalamus and mast cells. CRH activates glial cells and mast cells through CRH receptors and releases neuroinflammatory mediators. Stress also increases proinflammatory mediator release in the peripheral systems that can induce and augment neuroinflammation. Post-traumatic stress disorder (PTSD) is a traumatic-chronic stress related mental dysfunction. Currently there is no specific therapy to treat PTSD since its disease mechanisms are not yet clearly understood. Moreover, recent reports indicate that PTSD could induce and augment neuroinflammation and neurodegeneration in the pathogenesis of neurodegenerative diseases. Mast cells play a crucial role in the peripheral inflammation as well as in neuroinflammation due to brain injuries, stress, depression, and PTSD. Therefore, mast cells activation in brain injury, stress, and PTSD may accelerate the pathogenesis of neuroinflammatory and neurodegenerative diseases including AD. This review focusses on how mast cells in brain injuries, stress, and PTSD may promote the pathogenesis of AD. We suggest that inhibition of mast cells activation and brain cells associated inflammatory pathways in the brain injuries, stress, and PTSD can be explored as a new therapeutic target to delay or prevent the pathogenesis and severity of AD.