Heart rate variability: Pre-deployment predictor of post-deployment PTSD symptoms

Heart rate variability impairment during sleep in Veterans with REM sleep behavior disorder, traumatic brain injury, and posttraumatic stress disorder: An early potential window into autonomic dysfunction?

Individuals with comorbid REM sleep behavior disorder (RBD) and neurotrauma (defined by traumatic brain injury and post-traumatic stress disorder) have an earlier age of RBD symptom onset, increased RBD-related symptom severity and more neurological features indicative of prodromal synucleinopathy compared to RBD only. An early sign of neurodegenerative condition is autonomic dysfunction, which we sought to evaluate by examining heart rate variability during sleep. Participants with overnight polysomnography were recruited from the VA Portland Health Care System. Veterans without neurotrauma or RBD (controls; n=19), with RBD only (RBD, n=14), and with RBD and neurotrauma (RBD+NT, n=19) were evaluated. Eligible 5-minute NREM and REM epochs without apneas/hypopneas, microarousals, and ectopic beats were analyzed for frequency and time domain (e.g. low frequency power, LF; high frequency power, HF; root mean square of successive RR intervals, RMSSD; % of RR intervals that vary ≥50 ms, pNN50) heart rate variability outcomes. Heart rate did not significantly differ between groups in any sleep stage. Time domain and frequency domain variables (e.g., LF power, HF power, RMSSD, and pNN50) were significantly reduced in the RBD and RBD+NT groups compared to controls and RBD only during NREM sleep. There were no group differences detected during REM sleep. These data suggest significant reductions in heart rate variability during NREM sleep in RBD+NT participants, suggesting greater autonomic dysfunction compared to controls or RBD alone. Heart rate variability during sleep may be an early, promising biomarker, yielding mechanistic insight for diagnosis and prognosis of early neurodegeneration in this vulnerable population.

STATEMENT OF SIGNIFICANCE

Comorbid REM sleep behavior disorder (RBD) and neurotrauma (NT, traumatic brain injury + post-traumatic stress disorder; RBD+NT) is associated with increased neurodegenerative symptom burden and worsened health. Sleep and autonomic function are integrally and bidirectionally related to neurodegenerative processes. In the current study, we sought to determine if early signs of autonomic dysfunction, measured via heart rate variability (HRV), were present during sleep in comorbid RBD+NT compared to RBD only and controls. Our data show reduced time and frequency domain HRV during NREM sleep in RBD+NT Veterans compared to RBD only and controls. These data contribute evidence that participants with RBD and comorbid NT demonstrate significantly worse autonomic dysfunction compared to age/sex matched participants with RBD alone.

Enhancing Aviation Safety through AI-Driven Mental Health Management for Pilots and Air Traffic Controllers

This article provides an overview of the mental health challenges faced by pilots and air traffic controllers (ATCs), whose stressful professional lives may negatively impact global flight safety and security. The adverse effects of mental health disorders on their flight performance pose a particular safety risk, especially in sudden unexpected startle situations. Therefore, the early detection, prediction and prevention of mental health deterioration in pilots and ATCs, particularly among those at high risk, are crucial to minimize potential air crash incidents caused by human factors. Recent research in artificial intelligence (AI) demonstrates the potential of machine and deep learning, edge and cloud computing, virtual reality and wearable multimodal physiological sensors for monitoring and predicting mental health disorders. Longitudinal monitoring and analysis of pilots' and ATCs physiological, cognitive and behavioral states could help predict individuals at risk of undisclosed or emerging mental health disorders. Utilizing AI tools and methodologies to identify and select these individuals for preventive mental health training and interventions could be a promising and effective approach to preventing potential air crash accidents attributed to human factors and related mental health problems. Based on these insights, the article advocates for the design of a multidisciplinary mental healthcare ecosystem in modern aviation using AI tools and technologies, to foster more efficient and effective mental health management, thereby enhancing flight safety and security standards. This proposed ecosystem requires the collaboration of multidisciplinary experts, including psychologists, neuroscientists, physiologists, psychiatrists, etc. to address these challenges in modern aviation.

Psychophysiological reactions during the trauma-film paradigm and their predictive value for intrusions

Background: Adequate adaptation of the autonomic nervous system (ANS) is crucial in potentially life-threatening situations. The defence cascade provides a descriptive model of progressing dominant physiological reactions in such situations, including cardiovascular parameters and body mobility. The empirical evidence for this model is scarce, and the influence of physiological reactions in this model for predicting trauma-induced intrusions is unresolved.Objectives: Using a trauma-film paradigm, we aimed to test physiological reactions to a highly stressful film as an analogue to a traumatic event along the defence cascade model. We also aimed to examine the predictive power of physiological activity for subsequent intrusive symptoms.Method: Forty-seven healthy female participants watched a stressful and a neutral film in randomized order. Heart rate (HR), heart rate variability (HRV), and body sway were measured. Participants tracked frequency, distress, and quality of subsequent intrusions in a diary for 7 consecutive days.Results: For the stressful film, we observed an initial decrease in HR, followed by an increase, before the HR stabilized at a high level, which was not found during the neutral film. No differences in HRV were observed between the two films. Body sway and trembling frequency were heightened during the stressful film. Neither HR nor HRV predicted subsequent intrusions, whereas perceived distress during the stressful film did.Conclusions: Our results suggest that the physiological trauma-analogue response is characterized by an orientation response and subsequent hyperarousal, reaching a high physiological plateau. In contrast to the assumptions of the defence cascade model, the hyperarousal was not followed by downregulation. Potential explanations are discussed. For trauma-associated intrusions in the subsequent week, psychological distress during the film seems to be more important than physiological distress. Understanding the interaction between physiological and psychological responses during threat informs the study of ANS imbalances in mental disorders such as post-traumatic stress disorder.

Predicting Post-Traumatic Stress Disorder Treatment Response Using Heart Rate Variability to Virtual Reality Environment and Modified Stroop Task: An Exploratory Study

Predicting treatment response can inform treatment decisions, expectations, and optimize use of mental health treatment resources. This study examined heart rate (HR), heart rate variability (HRV), and a modified Stroop task (mStroop) to predict post-traumatic stress disorder (PTSD) treatment response. We report on an observational, longitudinal study with 45 U.S. veterans in outpatient PTSD care, who had deployed to Iraq or Afghanistan. HR and HRV were collected before, during, and after virtual reality (VR) combat and civilian scenes. HRV recovery was defined as HRV after a 3-minute VR simulation minus HRV during a VR scene. mStroop threat variables included index scores for combat and general threat. Self-report data were collected at baseline and 6 months later. The outcome variable was the 17-item Clinician Administered PTSD Scale (CAPS). Controlling for baseline CAPS and number of combat experiences, the following baseline HRV recovery variables were significant predictors of 6-month CAPS: standard deviation of normal beat to beat interval (SDNN) after combat scene minus SDNN during combat scene and low-frequency (LF HRV) after civilian scene minus LF during civilian scene. HRV at rest, HR reactivity, HR recovery, and mStroop scores did not predict treatment response. In conclusion, HRV recovery variables in the context of a standardized VR stressor were significant predictors of PTSD treatment response after controlling for baseline CAPS and number of combat experiences. The direction of this relationship indicates that greater baseline HRV recovery predicts lower 6-month PTSD symptom severity. This was an exploratory study in need of replication.

Heart Rate Variability in Psychiatric Disorders: A Systematic Review

Introduction

Heart rate variability (HRV) is a measure of the fluctuation in time interval between consecutive heart beats. Decreased heart rate variability has been shown to have associations with autonomic dysfunction in psychiatric conditions such as depression, substance abuse, anxiety, and schizophrenia, although its use as a prognostic tool remains highly debated. This study aims to review the current literature on heart rate variability as a diagnostic and prognostic tool in psychiatric populations.

Methods

A literature search was conducted using the MEDLINE, EMBASE, Cochrane, and PsycINFO libraries to identify full-text studies involving adult psychiatric populations that reported HRV measurements. From 1647 originally identified, 31 studies were narrowed down through an abstract and full-text screen. Studies were excluded if they enrolled adolescents or children, used animal models, enrolled patients with another primary diagnosis other than psychiatric as outlined by the diagnostic and statistical manual of mental disorders (DSM) V, or if they assessed HRV in the context of treatment rather than diagnosis. Study quality assessment was conducted using a modified Downs and Blacks quality assessment tool for observational rather than interventional studies. Data were reported in four tables: 1) summarizing study characteristics, 2) methods of HRV detection, 3) key findings and statistics, and 4) quality assessment.

Results

There is significant variability between studies in their methodology of recording as well as reporting HRV, which makes it difficult to meaningfully interpret data that is clinically applicable due to the presence of significant bias in existing studies. The presence of an association between HRV and the severity of various psychiatric disorders, however, remains promising.

Conclusion

Future studies should be done to further explore how HRV parameters may be used to enhance the diagnosis and prognosis of several psychiatric disorders.

Assessment of the activities physiological cost of the defense forces officers in Ukraine using miniature ECG device

Introduction

In the principles of the organization of armed struggle of the defense forces of most developed countries of the world, considerable attention is paid to the evaluation of combat readiness of the military personnel. This procedure is conditioned by such interconnected goals of the armed struggle as the maximum realization of the combat potential and the minimization of personnel losses. The purpose of the work is to determine the physiological cost of the activities of the soldiers of the Defense Forces of Ukraine with the help of miniature electrocardiographic hardware and software complexes.

Methods

In the research, ultra-miniature ECG devices worn on the body for a long time, so-called wearable "on-body" ECG patch devices, were used in various combat conditions. When analyzing the data, the principle of multi-faceted ECG analysis was implemented, which allows you to obtain complete and physiologically based information, which includes 4 blocks: heart rate variability (HRV), amplitude-time indicators of the ECG, heart rhythm disorders, and psycho- emotional state.

Results

In this study, a complex index of the functional state formed based on estimates of generally accepted and original indicators of heart rhythm variability, the shape of the teeth and complexes of the electrocardiogram, as well as an index of the psycho-emotional state formed according to the same principles based on the analysis of heart rhythm variability according to the modified McCraty algorithm (USA) was evaluated. Examination with the help of the complex is carried out in a state of rest, sitting or lying down.

Discussion

The sensitivity of the developed monitoring system is good enough to detect the changes in the functional state both in the case of short-term (for hours) intense physical or psycho-emotional stress and more chronic (for days and weeks) stress depending on the nature of the task being done. The proposed methods and means can be considered an important tool to support the commander's decision-making regarding the ability of personnel from the point of view of their functional state to perform combat tasks.

Military personnel's stress reactivity during pre-deployment in a war zone

Many studies have been conducted on the numerous negative post-deployment outcomes for military personnel. However, data on service members' pre-deployment stress reactivity are absent. This is a serious gap in existing research, as stress has an important regulatory role. This study aimed to determine possible manifestations of military personnel's stress reactivity during pre-deployment in a war zone in eastern Ukraine. The study involved 270 Ukrainian service members (all male, aged 18 to 58 years). Sample 1 (n = 108) were preparing to be deployed for the first time, sample 2 (n = 84) were preparing to be deployed and had previous experience of deployment, and sample 3 (n = 108) were not preparing to deploy and had no previous deployment experience. We used the Ukrainian adaptation of the Giessen Subjective Complaints List (GBB-24), the Symptom Checklist-90-Revised (SCL-90-R), the Short Screening Scale for DSM-IV posttraumatic stress disorder and the Combat Exposure Scale (CES). We found that indicators for physical complaints, psychological problems and psychopathological and posttraumatic symptoms among service members from samples 1 and 2 were significantly higher than those of sample 3 in 15 of 18 cases (p < 0.001-0.05). The indicators obtained for sample 2 were higher than those of sample 1 in six of nine cases (p < 0.001-0.05). Both our study hypotheses were confirmed. The present findings can be used to develop efficient psychological interventions for military personnel during pre-deployment in a war zone.

Heart and brain traumatic stress biomarker analysis with and without machine learning: A scoping review

The enigma of post-traumatic stress disorder (PTSD) is embedded in a complex array of physiological responses to stressful situations that result in disruptions in arousal and cognitions that characterise the psychological disorder. Deciphering these physiological patterns is complex, which has seen the use of machine learning (ML) grow in popularity. However, it is unclear to what extent ML has been used with physiological data, specifically, the electroencephalogram (EEG) and electrocardiogram (ECG) to further understand the physiological responses associated with PTSD. To better understand the use of EEG and ECG biomarkers, with and without ML, a scoping review was undertaken. A total of 124 papers based on adult samples were identified comprising 19 ML studies involving EEG and ECG. A further 21 studies using EEG data, and 84 studies employing ECG meeting all other criteria but not employing ML were included for comparison. Identified studies indicate classical ML methodologies currently dominate EEG and ECG biomarkers research, with derived biomarkers holding clinically relevant diagnostic implications for PTSD. Discussion of the emerging trends, algorithms used and their success is provided, along with areas for future research.

Reduced heart rate variability and expressive suppression interact to prospectively predict COVID-19 pandemic-related post-traumatic stress symptoms

The COVID-19 pandemic is a unique period of stress that, in some cases, led to post-traumatic stress symptoms (PTSSs). Emotion regulation strategies are known to modulate the emotional response to stressful events. Expressive suppression (ES) is a maladaptive strategy related to the exacerbation of the physiological stress response. Heart rate variability (HRV), an index of cardiac autonomic balance strictly related to ES, was also shown to predict PTSSs. This was the first study to investigate whether the pre-pandemic ES use and resting-state HRV predicted pandemic-related PTSSs. Before the pandemic, 83 (58 females) university students completed the Emotion Regulation Questionnaire (ERQ), self-report measures of anxiety and depressive symptoms, and a three-minute resting-state electrocardiogram recording. After 12 months, 61 (45 females) participants completed a self-report measure of pandemic-related PTSSs and repeated the self-report psychological measures. Pre-pandemic anxiety symptoms prospectively predicted greater PTSSs. Moreover, a significant interaction between HRV and ES in predicting PTSSs emerged, whereby those who had higher levels of ES and reduced HRV showed higher PTSSs. These findings suggest that an integrated assessment of HRV and ES might be useful for identifying individuals who are more vulnerable to the development of PTSSs during crises.

Intranasal oxytocin administration impacts the acquisition and consolidation of trauma-associated memories: a double-blind randomized placebo-controlled experimental study in healthy women

Intrusive memories are a hallmark symptom of post-traumatic stress disorder (PTSD) and oxytocin has been implicated in the formation of intrusive memories. This study investigates how oxytocin influences the acquisition and consolidation of trauma-associated memories and whether these effects are influenced by individual neurobiological and genetic differences. In this randomized, double-blind, placebo-controlled study, 220 healthy women received either a single dose of intranasal 24IU oxytocin or a placebo before exposure to a trauma film paradigm that solicits intrusive memories. We used a "general random forest" machine learning approach to examine whether differences in the noradrenergic and hypothalamic-pituitary-adrenal axis activity, polygenic risk for psychiatric disorders, and genetic polymorphism of the oxytocin receptor influence the effect of oxytocin on the acquisition and consolidation of intrusive memories. Oxytocin induced significantly more intrusive memories than placebo did (t(188.33) = 2.12, p = 0.035, Cohen's d = 0.30, 95% CI 0.16-0.44). As hypothesized, we found that the effect of oxytocin on intrusive memories was influenced by biological covariates, such as salivary cortisol, heart rate variability, and PTSD polygenic risk scores. The five factors that were most relevant to the oxytocin effect on intrusive memories were included in a Poisson regression, which showed that, besides oxytocin administration, higher polygenic loadings for PTSD and major depressive disorder were directly associated with a higher number of reported intrusions after exposure to the trauma film stressor. These results suggest that intranasal oxytocin amplifies the acquisition and consolidation of intrusive memories and that this effect is modulated by neurobiological and genetic factors. Trial registration: NCT03031405.

Assessing the Clinical Utility of a Wearable Device for Physiological Monitoring of Heart Rate Variability in Military Service Members with Traumatic Brain Injury

Introduction: Autonomic dysfunction has been implicated as a consequence of traumatic brain injury (TBI). Heart rate variability (HRV) may be a viable measure of autonomic dysfunction that could enhance rehabilitative interventions for individuals with TBI. This pilot study sought to assess the feasibility and validity of using the Zeriscope™ platform system in a real-world clinical setting to measure HRV in active-duty service members with TBI who were participating in an intensive outpatient program. Methods: Twenty-five service members with a history of mild, moderate, or severe TBI were recruited from a military treatment facility. A baseline assessment was conducted in the cardiology clinic where point validity data were obtained by comparing a 5-min recording of a standard 12-lead electrocardiogram (ECG) output against the Zeriscope platform data. Results: Compared with the ECG device, the Zeriscope device had a concordance coefficient (rc) of 0.16, falling below the standard deemed to represent acceptable accuracy in HR measurement (i.e., 0.80). Follow-up analyses excluding outliers did not significantly improve the concordance coefficient to an acceptable standard for the total participant sample. System Usability Survey responses showed that participants rated the Zeriscope system as easy to use and something that most people would learn to use quickly. Conclusions: This study demonstrated promise in ambulatory HRV measurement in a representative military TBI sample. Future research should include further refinement of such ambulatory devices to meet the specifications required for use in a military active-duty TBI population.

Modification in Psychophysiological Stress Parameters of Soldiers after an Integral Operative Training Prior to a Real Mission

(1) Background. Military personel could be defined as “Tactical Athletes”. However, experimental evidence about the effects of new HIIT trainings in comparison with traditional training schedules is lacking. The aim of this study was to experimentally analyze the modifications on psycho-physiological and performance response of soldiers after completing experimental integral operative training. (2) Methods. A total of 43 male subjects of a special unit force of the Spanish armed forces were randomly selected and assigned into the experimental and control groups assessed after training and after deploying in a real operation area. The experimental group underwent an integral operative pre-mission 6-week training (IOT), and the control group, the 6-week traditional training. (3) Results. HIIT-based integral operative training significantly improved combat performance (melee combat score) and the psychophysiological stress response, as measured by heart rate variability indexes. (4) Conclusion. This study provides experimental evidence supporting a new integral operative effective for improved autonomic regulation, reduced perceived stress, melee and close-quarter combat techniques, in addition to aerobic and anaerobic performance and lower body strength in comparison with the traditional training.

Comparison of the Cardiovascular Effects of Extreme Psychological and Physical Stress Tests in Male Soccer Players

Background: The purpose of our study was to compare the physiological effects of extreme physical and psychological stress tests in male soccer players, since these two types of stress apply to athletes with high performance requirements. Methods: A total of 63 healthy male soccer players participated in this study, all of whom underwent both of the tests. A physical stress test was carried out in an exercise physiology laboratory, where subjects completed an incremental treadmill running test to full exhaustion, and a psychological test was performed in a military tactical room, where subjects met a street offence situation. Heart rate variability (HRV) and blood pressure (BP) were recorded directly before, immediately after, and 30 min after the stress tests. Results: The majority of HRV indices changed significantly in both stress protocols. Inverse, significant changes (positive for the physical test, negative for the psychological test, p < 0.001) were found when comparing the alterations of HRV indices between the tests. Significant differences were found in the changes in systolic (p = 0.003) and diastolic (p < 0.001) BP between the test protocols, and also between the baseline and post-test measurements (p < 0.001). Conclusion: Both HRV and BP are sensitive physiological parameters to measure the impact of extreme physical and/or psychological stress

A systematic literature review of AI-based digital decision support systems for post-traumatic stress disorder

OBJECTIVE

Over the last decade, an increase in research on medical decision support systems has been observed. However, compared to other disciplines, decision support systems in mental health are still in the minority, especially for rare diseases like post-traumatic stress disorder (PTSD). We aim to provide a comprehensive analysis of state-of-the-art digital decision support systems (DDSSs) for PTSD.

METHODS

Based on our systematic literature review of DDSSs for PTSD, we created an analytical framework using thematic analysis for feature extraction and quantitative analysis for the literature. Based on this framework, we extracted information around the medical domain of DDSSs, the data used, the technology used for data collection, user interaction, decision-making, user groups, validation, decision type and maturity level. Extracting data for all of these framework dimensions ensures consistency in our analysis and gives a holistic overview of DDSSs.

RESULTS

Research on DDSSs for PTSD is rare and primarily deals with the algorithmic part of DDSSs (n = 17). Only one DDSS was found to be a usable product. From a data perspective, mostly checklists or questionnaires were used (n = 9). While the median sample size of 151 was rather low, the average accuracy was 82%. Validation, excluding algorithmic accuracy (like user acceptance), was mostly neglected, as was an analysis concerning possible user groups.

CONCLUSION

Based on a systematic literature review, we developed a framework covering all parts (medical domain, data used, technology used for data collection, user interaction, decision-making, user groups, validation, decision type and maturity level) of DDSSs. Our framework was then used to analyze DDSSs for post-traumatic stress disorder. We found that DDSSs are not ready-to-use products but are mostly algorithms based on secondary datasets. This shows that there is still a gap between technical possibilities and real-world clinical work.

Pre-pandemic autonomic nervous system activity predicts mood regulation expectancies during COVID-19 in Israel

Despite the unfolding impact of the COVID‐19 pandemic on psychological well‐being, there is a lack of prospective studies that target physiological markers of distress. There is a need to examine physiological predictors from the pre‐pandemic period to identify and treat individuals at‐risk. In this study, our aim was to use pre‐pandemic markers of autonomic nervous system (ANS) parasympathetic and sympathetic regulation to predict individuals' psychological well‐being during the crisis. We also assessed the role of mood regulation expectancies as a mediator of the association between pre‐pandemic physiological measures and COVID‐related well‐being. In May to June 2020, 185 Israeli adults completed online questionnaires assessing their mood regulation expectancies since COVID‐19 began, and their current well‐being. These individuals had participated in lab studies 1.5–3 years prior to this assessment, where their physiological measures were taken, including respiratory sinus arrhythmia (RSA) and skin conductance level (SCL). RSA was positively related to mood regulation expectancies during COVID‐19 (b = 3.46, 95% CI [0.84, 6.05]). Mood regulation expectancies, in turn, positively predicted well‐being during the crisis (b = 0.021, 95% CI [0.016, 0.027]). The mediation was significant and moderated by SCL (index = −0.09, 95% CI [−0.02, −0.0001]), such that it was strongest for individuals with low SCL. We point to pre‐pandemic physiological mechanisms underlying individuals' mental well‐being during the COVID‐19 pandemic. These findings have theoretical, diagnostic, and clinical implications that may refine our understanding of the physiological basis of resilience to the COVID‐19 pandemic and thus may be implemented to identify and assist individuals in these times.

Our study offers a unique psychophysiological approach to predicting mood regulation and mental well‐being during COVID‐19 from pre‐pandemic resting physiological activity. We show that pre‐pandemic markers of the autonomic nervous system, which were collected during routine 2–3 years prior to the pandemic, allow us to prospectively understand emotion regulation and well‐being during COVID‐19.

Reexamination of diathesis stress and neurotoxic stress theories: A qualitative review of pre-trauma neurobiology in relation to posttraumatic stress symptoms

OBJECTIVE

Associations of neurobiological differences with posttraumatic stress disorder (PTSD) have generated interest in their temporal relation. Support has been voiced for the neurotoxic stress theory (NST) in which neurobiological differences develop following exposure and PTSD development. In contrast, the diathesis stress theory (DST) posits that neurobiological differences existed prior to exposure and may be vulnerability factors for PTSD. Studies in the first wave of neurobiological PTSD research were all cross sectional, but a second wave of research followed which used prospective repeated-measures designs that measured neurobiology prior to trauma exposure experiences, allowing greater causal inference.

METHODS

This study reviewed the second-wave studies in hopes of developing a preliminary consensus to support either the NST or the DST based on this more powerful prospective, repeated-measures study design.

RESULTS

Twenty-five second-wave studies were located that measured neurobiology prior to traumatic experiences. Nineteen studies supported the DST. Of 10 studies that were capable of testing the NST, only 3 were supportive.

CONCLUSION

The implications of the NST versus the DST have profound implications for understanding the fragility of the human brain and possible paths forward for future research on assessment, treatment, and social policy.

The role of stress reactivity and pre-injury psychosocial vulnerability to psychological and physical health immediately after traumatic injury

BACKGROUND

Traumatic injuries can have long-term negative impacts on health, especially psychological health. A biopsychosocial approach is recommended to identify those likely to experience psychosocial stress, however large individual differences exist in stress reactivity and post-injury health that remain unexplored. Therefore, we investigated autonomic nervous system (ANS) stress responses and pre-existing psychosocial vulnerability as contributors to health in individuals who sustained a traffic-related injury.

METHODS

120 adults with traffic-related injury and 112 non-injury controls underwent an integrative ANS (cardiac and skin conductance) assessment and a health-related assessment at 3-6 weeks post-injury. Propensity score matching based on six pre-injury psychosocial vulnerability factors (age, sex, education, prior mental/physical health, socioeconomic status) guided the definition of high vulnerability (HV) and low vulnerability (LV) injury subgroups, with the LV subgroup having similar propensity scores to non-injury controls. A three-group comparative analysis of ANS responsivity (baseline, reactivity, recovery/rebound) and post-injury health was performed.

RESULTS

The HV subgroup exhibited the most negative immediate post-injury mental health profile and less adaptive ANS response patterns, indicating greater stress vulnerability/reactivity. Significant differences were found for psychological health (elevated psychological distress and catastrophizing), but not physical health (injury factors, pain, fatigue, physical wellbeing). HV participants showed sympathetic predominance at resting baseline (lower parasympathetic activity and/or elevated heart rate) compared to the LV and control groups, as well as smaller parasympathetic decrease during a cognitive task compared to controls. Despite preserved capacity for restoring initial homeostasis in both injury subgroups during recovery, there was some indication of blunted post-task sympathetic deactivation (larger sympathetic decrease) and reduced overall ANS adaptability (reduction in total power of heart rate variability spectrum), suggesting relative reduced capacity to face stressors compared to controls.

CONCLUSIONS

Findings suggest that baseline resting ANS regulation, particularly parasympathetic activity, and pre-injury psychosocial factors are key contributors to individual psycho-biological responses following traumatic injury, and are therefore potential stress vulnerability markers. Post-stress recovery patterns may represent a novel physiological signature for a "biological intrinsic" vulnerability early after the injury. These findings provide direction for improved early identification and management of injured individuals, including innovative preventive interventions that target ANS regulation.

Heart Rate Complexity in US Army Forward Surgical Teams During Pre Deployment Training

INTRODUCTION

For trauma triage, the US Army has developed a portable heart rate complexity (HRC) monitor, which estimates cardiac autonomic input and the activity of the hypothalamic-pituitary-adrenal (HPA) axis. We hypothesize that autonomic/HPA stress associated with predeployment training in U.S. Army Forward Surgical Teams will cause changes in HRC.

MATERIALS AND METHODS

A prospective observational study was conducted in 80 soldiers and 10 civilians at the U.S. Army Trauma Training Detachment. Heart rate (HR, b/min), cardiac output (CO, L/min), HR variability (HRV, ms), and HRC (Sample Entropy, unitless), were measured using a portable non-invasive hemodynamic monitor during postural changes, a mass casualty (MASCAL) situational training exercise (STX) using live tissue, a mock trauma (MT) STX using moulaged humans, and/or physical exercise.

RESULTS

Baseline HR, CO, HRV, and HRC averaged 72 ± 11b/min, 5.6 ± 1.2 L/min, 48 ± 24 ms, and 1.9 ± 0.5 (unitless), respectively. Supine to sitting to standing caused minimal changes. Before the MASCAL or MT, HR and CO both increased to ~125% baseline, whereas HRV and HRC both decreased to ~75% baseline. Those values all changed an additional ~5% during the MASCAL, but an additional 10 to 30% during the MT. With physical exercise, HR and CO increased to >200% baseline, while HRV and HRC both decreased to 40 to 60% baseline; these changes were comparable to those caused by the MT. All the changes were P < 0.05.

CONCLUSIONS

Various forms of HPA stress during Forward Surgical Team STXs can be objectively quantitated continuously in real time with a portable non-invasive monitor. Differences from resting baseline indicate stress anticipating an impending STX whereas differences between average and peak responses indicate the relative stress between STXs. Monitoring HRC could prove useful to field commanders to rapidly and objectively assess the readiness status of troops during STXs or repeated operational missions. In the future, health care systems and regulatory bodies will likely be held accountable for stress in their trainees and/or obliged to develop wellness options and standardize efforts to ameliorate burnout, so HRC metrics might have a role, as well.

Energy Medicine treatments for hand and wrist pain: A pilot study

INTRODUCTION

The term "energy medicine" describes healing modalities that manipulate or channel purported subtle energies associated with the body. The objectives of this pilot study were to determine the feasibility of studying energy medicine for people with carpal tunnel pain and gathering relevant preliminary data.

METHODS

Following a prospective, within-participant design, participants were recruited to experience a 30 min treatment from one of 17 energy medicine practitioners. Of 374 adults experiencing carpal tunnel pain who were screened for the study, 190 received an energy medicine treatment. Practitioners delivered treatments at close distance, some with and some without light, stationary touch. Outcome measures were collected before, during, and immediately after the treatment, and three weeks later. The primary outcome measure was self-reported pain. Secondary subjective measures included credibility regarding energy medicine and expectancy regarding the efficacy of treatments, pain interference, sleep quality, well-being, mood, and sense of personal transformation. Physiological measures included median nerve conduction velocity, heart rate variability, heart rate synchrony (between the participant and practitioner), and expression levels of neuroinflammation-related genes.

RESULTS

On average, self-reported current pain scores decreased 2.0 points post-session and 1.3 points at three weeks compared to baseline values using a 0-10 point scale with 10 denoting worst pain (F(2, 565) = 3.82 p <0.000005). This effect was not influenced by the participants' level of expectancy or credibility regarding the energy medicine modality. Well-being, negative emotion, and sleep quality scores significantly improved at the follow-up visit. Multiple heart rate variability measures significantly changed reflecting increased parasympathetic activity which may indicate decreased stress. No other secondary outcome showed significant change.

DISCUSSION

Studying the administration of energy medicine to people with carpal tunnel pain is feasible, although requiring a documented carpal tunnel syndrome diagnosis proved to be prohibitive for recruitment. Our finding of preliminary evidence for positive effects in pain and pain-related outcomes after a single session of energy medicine warrants further controlled investigation.

Autonomic Rehabilitation: Adapting to Change

Adaption to changes of external environment or internal health, the body-mind connection, or autonomic nervous system must be flexible and healthy. Population health studies with wearable technology and remote monitoring will lead to paradigm shifts in how to approach the physiology of emotion. Heart rate variability as a whole health biomarker could emerge as a foundation for a process beginning with objective habits and skills of real-time modulation with focused breathing for healthier decision making and autonomic health trajectory change. Physical medicine and rehabilitation is uniquely poised to refine an autonomic rehabilitation process in an integrative manner to help individuals adapt.

Toward a Taxonomy for Analyzing the Heart Rate as a Physiological Indicator of Posttraumatic Stress Disorder: Systematic Review and Development of a Framework

BACKGROUND

Posttraumatic stress disorder (PTSD) is a prevalent psychiatric condition that is associated with symptoms such as hyperarousal and overreactions. Treatments for PTSD are limited to medications and in-session therapies. Assessing the way the heart responds to PTSD has shown promise in detecting and understanding the onset of symptoms.

OBJECTIVE

This study aimed to extract statistical and mathematical approaches that researchers can use to analyze heart rate (HR) data to understand PTSD.

METHODS

A scoping literature review was conducted to extract HR models. A total of 5 databases including Medical Literature Analysis and Retrieval System Online (Medline) OVID, Medline EBSCO, Cumulative Index to Nursing and Allied Health Literature (CINAHL) EBSCO, Excerpta Medica Database (Embase) Ovid, and Google Scholar were searched. Non-English language studies, as well as studies that did not analyze human data, were excluded. A total of 54 studies that met the inclusion criteria were included in this review.

RESULTS

We identified 4 categories of models: descriptive time-independent output, descriptive and time-dependent output, predictive and time-independent output, and predictive and time-dependent output. Descriptive and time-independent output models include analysis of variance and first-order exponential; the descriptive time-dependent output model includes a classical time series analysis and mixed regression. Predictive time-independent output models include machine learning methods and analysis of the HR-based fluctuation-dissipation method. Finally, predictive time-dependent output models include the time-variant method and nonlinear dynamic modeling.

CONCLUSIONS

All of the identified modeling categories have relevance in PTSD, although the modeling selection is dependent on the specific goals of the study. Descriptive models are well-founded for the inference of PTSD. However, there is a need for additional studies in this area that explore a broader set of predictive models and other factors (eg, activity level) that have not been analyzed with descriptive models.

Resting high frequency heart rate variability and PTSD symptomatology in Veterans: Effects of respiration, role in elevated heart rate, and extension to spouses

Heart rate variability (HRV) associated with parasympathetic activity (i.e., cardiac vagal tone) is reduced in posttraumatic stress disorder (PTSD), but possible confounding effects of respiration have not been studied sufficiently. Further, reduced parasympathetic inhibition might contribute to elevated heart rate (HR) in PTSD. Finally, reduced HRV in PTSD might extend to intimate partners, given their chronic stress exposure. In 65 couples (male Veterans, female partners), elevated PTSD symptomatology (n = 32; 28 met full DSM IV criteria, 4 fell slightly short) was documented by structured interview and self-reports. Baseline HR, high-frequency HRV (HF-HRV), cardiac pre-ejection period (PEP), and respiration rate and depth were measured via impedance cardiography. Veterans with PTSD symptoms displayed reduced lnHF-HRV, even when adjusting for respiration, but their partners did not. In mediational analyses, elevated resting HR in PTSD was accounted for by lnHF-HRV but not PEP. Results strengthen evidence regarding HF-HRV and elevated HR in PTSD.

Early posttraumatic autonomic and endocrine markers to predict posttraumatic stress symptoms after a preventive intervention with oxytocin

BACKGROUND

Efficient prevention of posttraumatic stress disorder (PTSD) needs to target individuals with an increased risk for adverse outcome after trauma. Prognostic or prescriptive biological markers assessed early posttrauma may inform personalized treatment recommendations.

OBJECTIVE

To test prognostic and prescriptive effects of early (posttraumatic) autonomic and endocrine markers on PTSD symptom development.

METHOD

Autonomic and endocrine markers were assessed within 12 days posttrauma and before treatment initiation within a randomized placebo-controlled trial investigating repeated oxytocin administration as preventive intervention for PTSD. Linear mixed effects models were used to test the effects of heart rate (variability), resting cortisol, morning cortisol and cortisol awakening response (CAR), cortisol suppression by dexamethasone and resting oxytocin on PTSD symptoms 1.5, 3 and 6 months posttrauma in men (n = 54), women using hormonal contraception (n = 27) and cycling women (n = 19).

RESULTS

We found significant prognostic effects of resting oxytocin and cortisol suppression. In women using hormonal contraception, higher oxytocin was associated with higher PTSD symptoms across follow-up. Stronger cortisol suppression by dexamethasone, reflecting increased glucocorticoid receptor feedback sensitivity, was associated with lower PTSD symptoms across follow-up in men, but with higher symptoms at 1.5 months in women using hormonal contraception. These effects were independent of treatment condition. No further significant prognostic or prescriptive effects were detected.

CONCLUSION

Our exploratory study indicates that resting oxytocin and glucocorticoid receptor feedback sensitivity early posttrauma are associated with subsequent PTSD symptom severity. Notably, prognostic effects depended on sex and hormonal contraception use, emphasizing the necessity to consider these factors in biomedical PTSD research.

The Physiological Regulation of Emotion During Social Interactions: Vagal Flexibility Moderates the Effects of a Military Parenting Intervention on Father Involvement in a Randomized Trial

To make prevention programs more effective and understand "what works for whom," evidence regarding what individual characteristics predict intervention responsiveness is needed. Previous studies have evaluated a military parent training program known as After Deployment Adaptive Parenting Tools/ADAPT, yet less is understood about the program's varying effects for fathers. We tested the physiological regulation of emotion during social interactions as a moderator predicting fathers' responsiveness in a randomized trial of ADAPT, in which emotion regulation was operationally measured through vagal flexibility (VF; dynamic changes in cardiac vagal tone). Families with a child aged between 4 and 13 years for whom physiological data were gathered (n = 145) were randomly assigned to ADAPT (14-week face-to-face group intervention) or a control group (services as usual). Fathers in these families were National Guard/Reserve members who had been deployed to war in Iraq and/or Afghanistan and recently returned. Prior to the intervention, cardiac data was collected in-home throughout a set of family interaction tasks and VF was operationalized as the changes in high frequency (HF) power of heart rate variability (HRV) from a reading task to a problem-solving task. Parenting behaviors were observed and coded based on theory-driven indicators pre-intervention and at 1-year follow-up. Results of structural equation modeling showed that VF significantly moderated fathers' intervention responsiveness, such that fathers with higher vs. lower VF exhibited more effective parenting at 1-year follow-up if they were randomized into ADAPT vs. the control group. This study is the first to demonstrate that parasympathetic vagal functioning may be a biomarker to predict response to a military parenting intervention to enhance parenting in combat deployed fathers. The implications for precision-based prevention are discussed.

The "Managed" or Damaged Heart? Emotional Labor, Gender, and Posttraumatic Stressors Predict Workplace Event-Related Acute Changes in Cortisol, Oxytocin, and Heart Rate Variability

Vital to the everyday operation of police services, police communicators (911 call-takers and dispatchers) are persistently subject to imminent challenges in the workplace; they must always be prepared to engage and deal with a wide variety of circumstances that provoke various intense emotions and physiological stress responses. Acute changes in cortisol, oxytocin, and heart rate variability are central to adaptive responses in stressful complex social interactions, but they might also be indicative of physiological dysregulation due to long-term psychosocial stress exposures. Thus, we examine acute stress-induced release of peripheral oxytocin and cortisol along with changes in heart rate variability, and how each relates to persistent workplace stressors and symptoms of posttraumatic stress. Findings indicate chronic forms of gendered workplace stress such as emotional labor, gender role stress and, posttraumatic stress each have differential associations with, and predict physiological responses to, acutely stressful events in the workplace. These associations suggest potential mechanisms through which communicators become more vulnerable to developing stress-related disorders such as posttraumatic stress injuries, especially after cumulative traumatic exposures in this context. The results also suggest potential pathways for the biological embedding of stressful gendered workplace experiences.

Entropy in Heart Rate Dynamics Reflects How HRV-Biofeedback Training Improves Neurovisceral Complexity during Stress-Cognition Interactions

Despite considerable appeal, the growing appreciation of biosignals complexity reflects that system complexity needs additional support. A dynamically coordinated network of neurovisceral integration has been described that links prefrontal-subcortical inhibitory circuits to vagally-mediated heart rate variability. Chronic stress is known to alter network interactions by impairing amygdala functional connectivity. HRV-biofeedback training can counteract stress defects. We hypothesized the great value of an entropy-based approach of beat-to-beat biosignals to illustrate how HRVB training restores neurovisceral complexity, which should be reflected in signal complexity. In thirteen moderately-stressed participants, we obtained vagal tone markers and psychological indexes (state anxiety, cognitive workload, and Perceived Stress Scale) before and after five-weeks of daily HRVB training, at rest and during stressful cognitive tasking. Refined Composite Multiscale Entropy (RCMSE) was computed over short time scales as a marker of signal complexity. Heightened vagal tone at rest and during stressful tasking illustrates training benefits in the brain-to-heart circuitry. The entropy index reached the highest significance levels in both variance and ROC curves analyses. Restored vagal activity at rest correlated with gain in entropy. We conclude that HRVB training is efficient in restoring healthy neurovisceral complexity and stress defense, which is reflected in HRV signal complexity. The very mechanisms that are involved in system complexity remain to be elucidated, despite abundant literature existing on the role played by amygdala in brain interconnections.

Heart rate variability: Can it serve as a marker of mental health resilience?: Special Section on "Translational and Neuroscience Studies in Affective Disorders" Section Editor, Maria Nobile MD, PhD

BACKGROUND

Stress resilience influences mental well-being and vulnerability to psychiatric disorders. Usually, measurement of resilience is based on subjective reports, susceptible to biases. It justifies the need for objective biological/physiological biomarkers of resilience. One promising candidate as biomarker of mental health resilience (MHR) is heart rate variability (HRV). The evidence for its use was reviewed in this study.

METHODS

We focused on the relationship between HRV (as measured through decomposition of RR intervals from electrocardiogram) and responses to laboratory stressors in individuals without medical and psychiatric diseases. We conducted a bibliographic search of publications in the PubMed for January 2010-September 2018.

RESULTS

Eight studies were included. High vagally mediated HRV before and/or during stressful laboratory tasks was associated with enhanced cognitive resilience to competitive/self-control challenges, appropriate emotional regulation during emotional tasks, and better modulation of cortisol, cardiovascular and inflammatory responses during psychosocial/mental tasks.

LIMITATIONS

All studies were cross-sectional, restricting conclusions that can be made. Most studies included only young participants, with some samples of only males or females, and a limited array of HRV indexes. Ecological validity of stressful laboratory tasks remains unclear.

CONCLUSIONS

Vagally mediated HRV may serve as a global index of an individual's flexibility and adaptability to stressors. This supports the idea of HRV as a plausible, noninvasive, and easily applicable biomarker of MHR. In future longitudinal studies, the implementation of wearable health devices, able to record HRV in naturalistic contexts of real-life, may be a valuable strategy to gain more reliable insight into this topic.

Heart Rate Variability as an Index of Resilience

Introduction

Resilience is the ability to maintain or quickly return to a stable physical and psychological equilibrium despite experiencing stressful events. Flexibility of the autonomic nervous system is particularly important for adaptive stress responses and may contribute to individual differences in resilience. Power spectrum analysis of heart rate variability (HRV) allows measurement of sympathovagal balance, which helps to evaluate autonomic flexibility. The present study investigated HRV as a broad index of resilience.

Materials and Methods

Twenty-four male participants from the Army National Guard Special Forces completed psychological measures known to relate to resilience and had HRV measured while undergoing stressful virtual environment scenarios. Pearson product-moment correlations were used to explore the relationships between HRV and resilience factors. All research was conducted with the oversight of the Human Subjects Review Committee of Fuller Theological Seminary.

Results

Trends toward significance were reported in order to provide results that would reasonably be expected in a study of higher power. Trends between resilience factors and HRV were found only during specific stress-inducing simulations (see Tables III).

Conclusion

Greater resilience to stress was associated with HRV during nonstress periods. Higher levels of resilience to traumatic events were associated with HRV during circumstances that were more stressful and emotionally distressing. Post hoc analysis revealed that specific factors including flexibility, emotional control, and spirituality were driving the relationship between general resilience and HRV following emotionally laden stressors. Less stress vulnerability was associated with HRV following intermittent brief stressors. In sum, HRV appears to represent some aspects of an individual’s overall resilience profile. Although resilience remains a complex, multidimensional construct, HRV shows promise as a global psychophysiological index of resilience. This study also offers important perspectives concerning ways to optimize both physical and psychological health.

Lower heart rate variability at baseline is associated with more consecutive intrusive memories in an experimental distressing film paradigm

Objectives: First evidence suggests that lower heart rate variability (HRV) is associated with more cognitive control deficits, a risk factor for the development of intrusive memories. The aim of this study was to determine whether high-frequency (HF) and low-frequency/high-frequency (LF/HF) ratio components of HRV at rest before an intrusion-inducing stressor would predict consecutive intrusive memories.Methods: Healthy female participants (n = 60) watched an established distressing film which induced intrusions. HF and LF/HF ratio were measured for 5 min prior to the stressor. The number of consecutive intrusions resulting from the distressing film was assessed throughout the following 4 days.Results: The main effect LF/HF ratio was associated with more intrusive memories, whereas, the main effect HF was associated with more intrusions on a trend level. The time × HF and time × LF/HF ratio interactions were significant, indicating a different course of number of intrusions over the 4 days depending on HF and LF/HF ratio. The regression-based parameter estimates revealed a significant association of lower HF and number of intrusions on days 1 and 2 and a significant association of higher LF/HF (i.e. lower HRV) and number of intrusions on day 1.Conclusions: The results suggest that higher baseline LF/HF ratio (i.e. lower HRV) predicts more intrusive memories in healthy women after watching a distressing film. Furthermore, the results suggest that women with lower baseline HF and higher LF/HF ratio recover at a slower rate from watching the distressing film by showing a delayed decrease in intrusive memories. Our findings support the notion that lower baseline HRV before a trauma might be a vulnerability factor for subsequent intrusive memories.

Heart Rate Variability and Cognitive Bias Feedback Interventions to Prevent Post-deployment PTSD: Results from a Randomized Controlled Trial

Introduction

There is a long history of pre-deployment PTSD prevention efforts in the military and effective pre-deployment strategies to prevent post-deployment PTSD are still needed.

Materials and Methods

This randomized controlled trial included three arms: heart rate variability biofeedback (HRVB), cognitive bias modification for interpretation (CBM-I), and control. The hypothesis was that pre-deployment resilience training would result in lower post-deployment PTSD symptoms compared with control. Army National Guard soldiers (n = 342) were enrolled in the Warriors Achieving Resilience (WAR) study and analyzed. The outcome was PTSD symptom severity using the PTSD Checklist - Military version (PCL) measured at pre-deployment, 3- and 12-month post-deployment. Due to the repeated measures for each participant and cluster randomization at the company level, generalized linear mixed models were used for the analysis. This study was approved by the Army Human Research Protection Office, Central Arkansas Veterans Healthcare System Institutional Review Board (IRB), and Southeast Louisiana Veterans Health Care System IRB.

Results

Overall, there was no significant intervention effect. However, there were significant intervention effects for subgroups of soldiers. For example, at 3-months post-deployment, the HRVB arm had significantly lower PCL scores than the control arm for soldiers with no previous combat zone exposure who were age 30 and older and for soldiers with previous combat zone exposure who were 45 and older (unadjusted effect size -0.97 and -1.03, respectively). A significant difference between the CBM-I and control arms was found for soldiers without previous combat zone exposure between ages 23 and 42 (unadjusted effect size -0.41). Similarly, at 12-months post-deployment, the HRVB arm had significantly lower PCL scores in older soldiers.

Conclusion

Pre-deployment resilience training was acceptable and feasible and resulted in lower post-deployment PTSD symptom scores in subgroups of older soldiers compared with controls. Strengths of the study included cluster randomization at the company level, use of iPod device to deliver the resilience intervention throughout the deployment cycle, and minimal disruption of pre-deployment training by using self-paced resilience training. Weaknesses included self-report app use, study personnel not able to contact soldiers during deployment, and in general a low level of PTSD symptom severity throughout the study. In future studies, it would important for the study team and/or military personnel implementing the resilience training to be in frequent contact with participants to ensure proper use of the resilience training apps.

Low vagal tone in two rat models of psychopathology involving high or low corticosterone stress responses

The two stress-responsive physiological systems, autonomic nervous system (ANS) and hypothalamus-pituitary-adrenal (HPA) axis exert complementary and interrelated actions in the organism. Individuals that suffer stress-related psychopathologies frequently present simultaneous alterations -i.e., either low or high- responsiveness- in both systems. However, there is scarce evidence establishing whether a priori alterations in these systems -i.e., independent of previous stress exposure- may predispose to the development of psychopathologies possibly due to the lack of animal models simultaneously involving aberrant HPA and SNS responses. In this study, we describe two animal models selectively bred according to their differential (either high, 'High', or low, 'Low') glucocorticoid responsiveness to stress, in comparison to a third line of rats that displays intermediate ('Inter') glucocorticoid responses. The two extreme lines may be considered distinct models of psychopathology; the High line representing a model of constitutive mood alterations while the Low line a model of vulnerability to develop stress-induced psychopathologies. We recorded the electrocardiogram in rats from the three lines and quantified heart rate variability and vagal tone indexes during rest and stress challenges. Rats from both High and Low lines displayed higher heart rate and lower basal vagal tone than the Inter group, both at resting and following stress exposure. Specific pharmacological manipulations probing the relative contribution of sympathetic and parasympathetic components on HR modulation confirmed a relative lower vagal tone in High and Low lines and discarded differences in the sympathetic regulation of heart rate between the lines. Therefore, the two genetically-selected High and Low glucocorticoid rat lines emerge as two valuable preclinical models of psychopathology involving two key risk factors for psychiatric and cardiovascular disorders, namely dysregulations in the HPA axis and cardiac vagal functioning.

Conditioned Pain Modulation in Sexual Assault Survivors

Sexual assault (SA) is associated with an increased risk of chronic pain, but the mechanisms for this relationship are poorly understood. To explore whether disrupted descending inhibition is involved, this study used a conditioned pain modulation task to study the inhibition of pain and the nociceptive flexion reflex (NFR; a correlate of spinal nociception) in 32 pain-free SA survivors. This group was compared with 32 pain-free, trauma-exposed persons without SA and a group of 40 pain-free persons who reported no trauma exposure. Conditioned pain modulation was assessed from painful electric stimulations (test stimulus) delivered to the ankle before, during, and after participants submerged their hand in painful 10°C water (conditioning stimulus). Pain ratings and NFR were assessed in response to test stimuli. All groups demonstrated significant inhibition of pain during conditioned pain modulation. However, only the no trauma exposure group demonstrated significant inhibition of NFR. The persons without SA group showed no inhibition of NFR, whereas the SA group showed significant facilitation of the NFR. These findings suggest that trauma exposure may impair inhibitory cerebrospinal circuits, but that SA may specifically promote facilitation of spinal nociception. Perspective: This study suggests that trauma exposure disrupts the cerebrospinal inhibition of spinal nociception, but that exposure to SA further promotes chronic pain risk by facilitating spinal nociception. This finding help may help to elucidate the pain risk mechanisms in trauma survivors.

A common neural substrate for elevated PTSD symptoms and reduced pulse rate variability in combat-exposed veterans

Previous studies have identified reduced heart rate variability (HRV) in post-traumatic stress disorder (PTSD), which may temporally precede the onset of the disorder. A separate line of functional neuroimaging research in PTSD has consistently demonstrated hypoactivation of the ventromedial prefrontal cortex (vmPFC), a key aspect of a descending neuromodulatory system that exerts inhibitory control over heart rate. No research to date, however, has simultaneously investigated whether altered vmPFC activation is associated with reduced HRV and elevated PTSD symptoms in the same individuals. Here, we collected fMRI data during alternating conditions of threat of shock and safety from shock in 51 male combat-exposed veterans with either high or low levels of PTSD symptoms. Pulse rate variability (PRV)-a HRV surrogate calculated from pulse oximetry-was assessed during a subsequent resting scan. Correlational analyses tested for hypothesized relationships between reduced vmPFC activation, lower PRV, and elevated PTSD symptomatology. We found that PTSD re-experiencing symptoms were inversely associated with high-frequency (HF)-PRV, thought to primarily reflect parasympathetic control of heart rate, in veterans with elevated PTSD symptoms. Reduced vmPFC activation for the contrast of safety-threat was associated both with lower HF-PRV and elevated PTSD re-experiencing symptoms. These results tie together previous observations of reduced HRV/PRV and impaired vmPFC function in PTSD and call for further research on reciprocal brain-body relationships in understanding PTSD pathophysiology.

Vagus nerve stimulation as a tool for enhancing extinction in exposure-based therapies

RATIONALE

Emotionally traumatic experiences can lead to maladaptive memories that are enduring and intrusive. The goal of exposure-based therapies is to extinguish conditioned fears through repeated, unreinforced exposures to reminders of traumatic events. The extinction of conditioned fear depends upon the consolidation of new memories made during exposure to reminders. An impairment in extinction recall, observed in certain patient populations, can interfere with progress in exposure-based therapies, and the drive to avoid thoughts and reminders of the trauma can undermine compliance and increase dropout rate. Effective adjuncts to exposure-based therapies should improve the consolidation and maintenance of the extinction memory or improve the tolerability of the therapy. Under stressful conditions, the vagus nerve responds to elevations in epinephrine and signals the brain to facilitate the storage of new memories while, as part of the parasympathetic nervous system, it slows the sympathetic response.

OBJECTIVE

Here, we review studies relevant to fear extinction, describing the anatomical and functional characteristics of the vagus nerve and mechanisms of vagus nerve stimulation (VNS)-induced memory enhancement and plasticity.

RESULTS

We propose that stimulation of the left cervical vagus nerve during exposure to conditioned cues signals the brain to store new memories just as epinephrine or emotional arousal would do, but bypasses the peripheral sympathetic "fight-or-flight" response.

CONCLUSIONS

In support of this hypothesis, we have found that VNS accelerates extinction and prevents reinstatement of conditioned fear in rats. Finally, we propose future studies targeting the optimization of stimulation parameters and the search for biomarkers of VNS effectiveness that may improve exposure therapy outcomes.

Effects of heart rate variability biofeedback training in athletes exposed to stress of university examinations

Introduction

Heart rate variability biofeedback (HRV-BFB) training, a method whereby one controls an unusually low breathing rate to reach cardiac coherence, has been shown to reduce anxiety and improve cardiac autonomic markers in diseased people, but much less is known about HRV-BFB benefits in healthy people. Here we investigated potential benefits in young competitors experiencing stress during university examinations as well as persistence of benefits after HRV-BFB training cessation.

Methods

A group of sports students (n = 12) practiced 5-min HRV-BFB training twice a day for 5-weeks using URGOfeel^® (URGOTECH) and was compared to a control group (n = 6). University examinations occurred immediately after HRV-BFB training (Exam1), then 12-weeks later (Exam2). Anxiety markers and cardiac autonomic markers were assessed at baseline, Exam1 and Exam2. Principal Component Analyses (PCA) that combined all these markers were computed at Exam1 and Exam2 to emphasize covariations.

Results

At Exam 1, immediately after HRV-BFB training cessation, the experimental group demonstrated greater autonomic markers but similar states of anxiety when compared to the Control group. Twelve weeks later at Exam2, autonomic markers were greater and anxiety scores were lesser among the experimental group. PCA highlighted covariations only within cardiac autonomic markers at Exam1. Rather, variations in cardiac markers were associated with anxiety markers at Exam2.

Conclusion

Short sessions of HRV-BFB training for a brief period of 5 weeks bring substantial benefits to autonomic markers and anxiety levels in young competitors. Here beneficial effects persisted for 12 weeks. Dissociated profiles of anxiety and cardiac autonomic adaptations shed new light on the role of the amygdala in heart-brain interactions after cardiac coherence training.

Skin Conductance Reactivity to Standardized Virtual Reality Combat Scenes in Veterans with PTSD

Interest in virtual reality (VR) as a clinical tool to augment posttraumatic stress (PTSD) treatment has grown substantially in recent years due to advances in VR technology. Moreover, its potential assisted use in the PTSD diagnostic process has been recognized. In this study we examined physiological responding, skin conductance, to a standardized presentation of non-personalized combat-related VR events (e.g. encountering enemy fire; explosions) as compared to non-combat classroom VR events in 19 Veterans with and 24 Veterans without combat-related PTSD who had been deployed to Iraq and Afghanistan. Veterans watched a total of 12 VR scenarios-six combat-related and six non-combat-related-with each scenario gradually increasing in emotional intensity by adding more VR events in addition to repeating prior VR events. Results show that Veterans with PTSD displayed larger skin conductance reactivity across VR combat events, but not for non-combat VR events, as compared to combat Veterans without PTSD. Nevertheless, Veterans with and without PTSD showed a similar reduction of emotional arousal to repeated presentation of the same VR combat events. Within the PTSD sample, the elevated level of VR combat-related arousal correlated marginally with severity of hyperarousal symptoms. This study confirms that the use of a non-personalized and standardized VR presentation successfully distinguishes Veterans with PTSD from those without on a measure of psychophysiological arousal to combat-related VR stimuli. The assessment of physiological reactivity during the repeated presentation of standardized, trauma-related VR events highlights its use for PTSD assessment as well as treatment.

Autonomic and Brain Morphological Predictors of Stress Resilience

Stressful life events are an important cause of psychopathology. Humans exposed to aversive or stressful experiences show considerable inter-individual heterogeneity in their responses. However, the majority does not develop stress-related psychiatric disorders. The dynamic processes encompassing positive and functional adaptation in the face of significant adversity have been broadly defined as resilience. Traditionally, the assessment of resilience has been confined to self-report measures, both within the general community and putative high-risk populations. Although this approach has value, it is highly susceptible to subjective bias and may not capture the dynamic nature of resilience, as underlying construct. Recognizing the obvious benefits of more objective measures of resilience, research in the field has just started investigating the predictive value of several potential biological markers. This review provides an overview of theoretical views and empirical evidence suggesting that individual differences in heart rate variability (HRV), a surrogate index of resting cardiac vagal outflow, may underlie different levels of resilience toward the development of stress-related psychiatric disorders. Following this line of thought, recent studies describing associations between regional brain morphometric characteristics and resting state vagally-mediated HRV are summarized. Existing studies suggest that the structural morphology of the anterior cingulated cortex (ACC), particularly its cortical thickness, is implicated in the expression of individual differences in HRV. These findings are discussed in light of emerging structural neuroimaging research, linking morphological characteristics of the ACC to psychological traits ascribed to a high-resilient profile and abnormal structural integrity of the ACC to the psychophysiological expression of stress-related mental health consequences. We conclude that a multidisciplinary approach integrating brain structural imaging with HRV monitoring could offer novel perspectives about brain-body pathways in resilience and adaptation to psychological stress.

A Clinician's Guide to PTSD Biomarkers and Their Potential Future Use

No clinically validated biomarkers have yet been found to assist in the diagnosis and treatment of posttraumatic stress disorder (PTSD). Innovation in clinical trial design, however, has led to the study of biomarkers as part of testing new medications and psychotherapies. There may soon be viable biomarkers to assist in diagnosis of PTSD and prediction of illness trajectory, severity, and functional outcomes; subtyping; and treatment selection. Processes for the identification and validation of biomarker findings are complex, involving several stages of clinical testing before use. The authors provide an overview of issues regarding the clinical use of PTSD biomarkers and examine a set of genetic, epigenetic, and other blood-based markers along with physiological markers currently proposed as candidate tests for PTSD. Studies that have identified candidate biomarkers with relevance to treatment selection in PTSD are discussed as a promising area of research that may lead to changes in clinical practice.

e-PTSD: an overview on how new technologies can improve prediction and assessment of Posttraumatic Stress Disorder (PTSD)

Background: New technologies may profoundly change our way of understanding psychiatric disorders including posttraumatic stress disorder (PTSD). Imaging and biomarkers, along with technological and medical informatics developments, might provide an answer regarding at-risk patient's identification. Recent advances in the concept of 'digital phenotype', which refers to the capture of characteristics of a psychiatric disorder by computerized measurement tools, is one paradigmatic example. Objective: The impact of the new technologies on health professionals practice in PTSD care remains to be determined. The recent evolutions could disrupt the clinical practices and practitioners in their beliefs, ethics and representations, going as far as questioning their professional culture. In the present paper, we conducted an extensive search to highlight the articles which reflect the potential of these new technologies. Method: We conducted an overview by querying PubMed database with the terms [PTSD] [Posttraumatic stress disorder] AND [Computer] OR [Computerized] OR [Mobile] OR [Automatic] OR [Automated] OR [Machine learning] OR [Sensor] OR [Heart rate variability] OR [HRV] OR [actigraphy] OR [actimetry] OR [digital] OR [motion] OR [temperature] OR [virtual reality]. Results: We summarized the synthesized literature in two categories: prediction and assessment (including diagnostic, screening and monitoring). Two independent reviewers screened, extracted data and quality appraised the sources. Results were synthesized narratively. Conclusions: This overview shows that many studies are underway allowing researchers to start building a PTSD digital phenotype using passive data obtained by biometric sensors. Active data obtained from Ecological Momentary Assessment (EMA) could allow clinicians to assess PTSD patients. The place of connected objects, Artificial Intelligence and remote monitoring of patients with psychiatric pathology remains to be defined. These tools must be explained and adapted to the different profiles of physicians and patients. The involvement of patients, caregivers and health professionals is essential to the design and evaluation of these new tools.

Successful use of closed-loop allostatic neurotechnology for post-traumatic stress symptoms in military personnel: self-reported and autonomic improvements

BACKGROUND

Military-related post-traumatic stress (PTS) is associated with numerous symptom clusters and diminished autonomic cardiovascular regulation. High-resolution, relational, resonance-based, electroencephalic mirroring (HIRREM®) is a noninvasive, closed-loop, allostatic, acoustic stimulation neurotechnology that produces real-time translation of dominant brain frequencies into audible tones of variable pitch and timing to support the auto-calibration of neural oscillations. We report clinical, autonomic, and functional effects after the use of HIRREM® for symptoms of military-related PTS.

METHODS

Eighteen service members or recent veterans (15 active-duty, 3 veterans, most from special operations, 1 female), with a mean age of 40.9 (SD = 6.9) years and symptoms of PTS lasting from 1 to 25 years, undertook 19.5 (SD = 1.1) sessions over 12 days. Inventories for symptoms of PTS (Posttraumatic Stress Disorder Checklist - Military version, PCL-M), insomnia (Insomnia Severity Index, ISI), depression (Center for Epidemiologic Studies Depression Scale, CES-D), and anxiety (Generalized Anxiety Disorder 7-item scale, GAD-7) were collected before (Visit 1, V1), immediately after (Visit 2, V2), and at 1 month (Visit 3, V3), 3 (Visit 4, V4), and 6 (Visit 5, V5) months after intervention completion. Other measures only taken at V1 and V2 included blood pressure and heart rate recordings to analyze heart rate variability (HRV) and baroreflex sensitivity (BRS), functional performance (reaction and grip strength) testing, blood and saliva for biomarkers of stress and inflammation, and blood for epigenetic testing. Paired t-tests, Wilcoxon signed-rank tests, and a repeated-measures ANOVA were performed.

RESULTS

Clinically relevant, significant reductions in all symptom scores were observed at V2, with durability through V5. There were significant improvements in multiple measures of HRV and BRS [Standard deviation of the normal beat to normal beat interval (SDNN), root mean square of the successive differences (rMSSD), high frequency (HF), low frequency (LF), and total power, HF alpha, sequence all, and systolic, diastolic and mean arterial pressure] as well as reaction testing. Trends were seen for improved grip strength and a reduction in C-Reactive Protein (CRP), Angiotensin II to Angiotensin 1-7 ratio and Interleukin-10, with no change in DNA n-methylation. There were no dropouts or adverse events reported.

CONCLUSIONS

Service members or veterans showed reductions in symptomatology of PTS, insomnia, depressive mood, and anxiety that were durable through 6 months after the use of a closed-loop allostatic neurotechnology for the auto-calibration of neural oscillations. This study is the first to report increased HRV or BRS after the use of an intervention for service members or veterans with PTS. Ongoing investigations are strongly warranted.

TRIAL REGISTRATION

NCT03230890 , retrospectively registered July 25, 2017.

Physiological monitoring for healthy military personnel

Military employment commonly exposes personnel to strenuous physical exertion. The resulting interaction between occupational stress and individual susceptibility to illness demands careful management. This could extend to prospective identification of high physiological strain in healthy personnel, in addition to recognition and protection of vulnerable individuals. The emergence and ubiquitous uptake of ‘wearable’ physiological and medical monitoring devices might help to address this challenge, but requires that the right questions are asked in sourcing, developing, validating and applying such technologies. Issues that must be addressed include system requirements, such as the likelihood of end users deploying and using technology as intended; interpretation of data in relation to pretest probability, including the potential for false-positive results; differentiation of pathological states from normal physiology; responsibility for and consequences of acting on abnormal or unexpected results and cost-effectiveness. Ultimately, the performance of a single monitoring system, in isolation or alongside other measures, should be judged by whether any improvement is offered versus existing capabilities and at what cost to mission effectiveness.