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

The recovery of decreased executive attention in Tibetan migrants at high-altitude

Attention is one of the basic cognitive functions sensitive to high altitude, and most studies have focussed on exposure times of approximately 3 years; however, it is unclear how attention changes in migrants who have lived and worked at high altitude for nearly 20 years. We explored the dynamics of attentional networks and neurophysiological mechanisms in migrants over 3-20 years using the Attentional Network Test combined with Electrocardiograph and Electroencephalography and found a consistent quadratic correlation between exposure and executive control efficiency, P3 amplitude and heart rate variability (HRV), with a decrease followed by an increase/relative stability, with approximately 10 years being the breakpoint. However, neither linear nor quadratic trajectories were observed for the alerting and orienting network. Mediation analysis revealed that the P3 amplitude mediated the decrease and increase in executive control efficiency with exposure time depends on the breakpoint. Correlations between HRV and executive control efficiency and P3 amplitude suggest that U-shaped changes in executive control in migrants may be related to body homeostasis maintained by the autonomic nervous system, and that P3 amplitude may serve as a neurophysiological marker of migrants' adaptation/recovery from high-altitude exposure.

High Heart Rate Variability Buffers the Effect of Attachment Insecurity on Sleep Quality

OBJECTIVE

Sleep quality is an important health-protective factor. Psychosocial factors, including attachment orientation, may be valuable for understanding who is at risk of poor sleep quality and associated adverse health outcomes. High attachment anxiety is reliably associated with adverse health outcomes, whereas high attachment avoidance is associated with adverse health outcomes when co-occurring with poor self-regulatory capacity, indexed by heart rate variability (HRV). We examined the associations between attachment anxiety, attachment avoidance, HRV, and sleep quality.

METHODS

Using longitudinal data from a sample of 171 older adults measured four times over 1 year ( M = 66.18 years old; 67.83% women), we separated the between-person variance (which we call "trait") and within-person variance (which we call "state") for attachment anxiety, attachment avoidance, and HRV (via the root mean square of successive differences). Sleep quality was measured with the Pittsburgh Sleep Quality Index.

RESULTS

Higher trait attachment anxiety was associated with poorer global sleep quality ( B = 0.22, p = .005). Higher state attachment avoidance was associated with poorer sleep quality ( B = -0.13, p = .01), except for those with higher trait HRV. Higher state attachment anxiety was associated with poorer sleep quality ( B = -0.15, p = .002), except for those with higher or mean trait HRV. Higher trait attachment anxiety was associated with poorer sleep quality ( B = -0.31, p = .02), except for those with higher trait HRV.

CONCLUSIONS

High trait HRV mitigated the adverse effects of attachment insecurity on sleep quality. Our results suggest that people with high trait HRV had greater self-regulation capacity, which may enable them to enact emotion regulation strategies effectively.

The neuroimmune pathway of high-altitude adaptation: influence of erythrocytes on attention networks through inflammation and the autonomic nervous system

Introduction

Many studies have shown that the functional adaptation of immigrants to high-altitude is closely related to oxygen transport, inflammatory response and autonomic nervous system. However, it remains unclear how human attention changes in response to hypoxia-induced neurophysiological activity during high-altitude exposure.

Methods

In the present study, we analyzed the relationship between hypoxic-induced neurophysiological responses and attention networks in 116 immigrants (3,680 m) using an attention network test to simultaneously record electroencephalogram and electrocardiogram in combination with specific routine blood markers.

Results

Our analysis revealed that red blood cells exert an indirect influence on the three attention networks, mediated through inflammatory processes and heart rate variability.

Discussion

The present study provides experimental evidence for the role of a neuroimmune pathway in determining human attention performance at high- altitude. Our findings have implications for understanding the complex interactions between physiological and neurocognitive processes in immigrants adapting to hypoxic environments.

Daily-level associations between posttraumatic stress disorder symptoms and reactions to retrieving positive autobiographical memories

Trauma survivors with posttraumatic stress disorder (PTSD) report difficulties accessing and describing positive memories. To understand these patterns, we examined daily-level relations of PTSD symptoms with affective, cognitive (dwelling/rumination; pushing memory out of one's mind; suppression; avoidance; distraction; thinking about something else; remembering negative or positive memories/events; negative or positive thoughts; accepting or disapproving memory; reinterpreting memory), and behavioral (using alcohol/drugs; smoking cigarettes; cravings for or seeking out cigarettes/alcohol/drugs; craving, seeking out, or consuming large amounts of food; dissociation; engaging in risky behaviors; sharing memories; interference with ongoing task; arousal) reactions to retrieving positive memories. Eighty-eight trauma survivors (Mage= 39.89 years; 59.1% female) completed 7 daily measures of PTSD and reactions to retrieving positive memories. Days with more PTSD severity were associated with higher odds of same-day suppression, avoidance, distraction, thinking about something else, smoking cigarettes, craving substances, craving, seeking out, or consuming large amounts of food, dissociation, remembering negative memories/events/thoughts, engaging in risky behaviors, interference with ongoing tasks, and arousal (ORs=1.10-1.22); and greater negative affect (β = 0.27). Supplemental lagged analyses indicated some associations between previous-day reactions to positive memory retrieval and next-day PTSD severity and vice versa. Trauma survivors with PTSD symptoms report negative and avoidance-oriented reactions to retrieving positive memories.

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.

Oxytocin vs. placebo effects on intrusive memory consolidation using a trauma film paradigm: a randomized, controlled experimental study in healthy women

Oxytocin administration during a trauma analogue has been shown to increase intrusive memories, which are a core symptom of post-traumatic stress disorder (PTSD). However, it is unknown whether oxytocin influences the acquisition or the consolidation of the trauma. The current study investigates the effect of the activation of the oxytocin system during the consolidation of an analogue trauma on the formation of intrusive memories over four consecutive days and whether this effect is influenced by individual neurobiological, genetic, or psychological factors. We conducted a randomized double-blind placebo-controlled study in 217 healthy women. They received either a single dose of intranasal oxytocin (24 IU) or placebo after exposure to a trauma film paradigm, which reliably induces intrusive memories. We used a general random forest to examine a potential heterogeneous treatment effect of oxytocin on the consolidation of intrusive memories. Furthermore, we used a poisson regression to examine whether salivary alpha amylase activity (sAA) as a marker of noradrenergic activity and cortisol response to the film, polygenic risk score (PRS) for psychiatric disorders, and psychological factors influence the number of intrusive memories. We found no significant effect of oxytocin on the formation of intrusive memories (F(2, 543.16) = 0.75, p = 0.51, ηp2 = 0.00) and identified no heterogeneous treatment effect. We replicated previous associations of the PRS for PTSD, sAA and the cortisol response on intrusive memories. We further found a positive association between high trait anxiety and intrusive memories, and a negative association between the emotion regulation strategy reappraisal and intrusive memories. Data of the present study suggest that the consolidation of intrusive memories in women is modulated by genetic, neurobiological and psychological factors, but is not influenced by oxytocin. Trial registration: NCT03875391.

Effects of non-invasive vagus nerve stimulation on cognitive and autonomic correlates of perseverative cognition

Perseverative cognitions can provoke psychophysiological stress in the absence of an actual stressor and are considered important transdiagnostic vulnerability factors for several (mental) health issues. These stress-related cognitive processes are reflected by both cognitive (assessed by self-reports) and autonomic inflexibility (assessed by heart rate variability; HRV), with a key role attributed to the vagus nerve. Interestingly, modulation of the afferent branches of the vagus can be achieved with transcutaneous auricular vagus nerve stimulation (taVNS), a non-invasive technique that employs a low-intensity electrical current applied to the ear. In a sample of healthy individuals, we investigated the effects of taVNS of the left concha, compared to sham (earlobe) stimulation, on the cognitive and autonomic correlates of perseverative cognition following a psychosocial stress task. Interestingly, taVNS significantly reduced cognitive rigidity, reflected by reduced subjective perseverative thinking after psychosocial stress. Although there were no direct effects on autonomic correlates of perseverative cognition, individual differences in perseverative thinking after the stressor significantly affected the effects of taVNS on HRV. Specifically, more autonomic inflexibility during the stress task (i.e., reduced HRV) was associated with increases in perseverative thinking afterward for the sham condition, but not the active taVNS condition. Additional exploratory analyses revealed no significant moderation of stimulation intensity. Overall, the study findings endorse the association between perseverative cognitions and vagus nerve functioning.

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.

Salivary Cortisol and Alpha-Amylase in Posttraumatic Stress Disorder and Their Potential Role in the Evaluation of Cognitive Behavioral Treatment Outcomes

Alterations in HPA-axis and autonomic nervous system activity have been associated with posttraumatic stress disorder (PTSD) development and maintenance and are potentially associated with trauma-focused cognitive behavioral therapy (TF-CBT) outcomes. We examined the role of salivary cortisol (sCort) and alpha-amylase (sAA) in PTSD and TF-CBT outcomes in German Armed Forces service members (N = 100). Participants categorized as PTSD patients (n = 39), previously deployed healthy controls (n = 33), and nondeployed healthy controls (n = 28) provided diurnal profiles of sCort and sAA; PTSD patients provided samples before, immediately after, and 3 months after an internet-based TF-CBT intervention. No group differences emerged regarding total daily sCort and sAA output or daily slopes, ps = .224-.897, fs = 0.05-0.24. Participants with PTSD demonstrated a significantly attenuated sCort awakening response compared to deployed, p = .021, d = 0.59, but not nondeployed controls, p = .918, d = 0.08. Moreover, a significantly steeper sAA awakening response emerged in PTSD patients, p = .034, d = 0.67, and deployed controls, p = .014, d = 0.80, compared to nondeployed controls. From pretreatment to posttreatment (n = 21) and posttreatment to follow-up (n = 14), stable sCort, ps = .282-.628, fs = 0.34-0.49, and sAA concentrations, ps = .068-.758, fs = 0.24-1.13 paralleled a nonsignificant treatment effect. Both PTSD and trauma exposure were associated with alterations in awakening responses, but further investigation is needed to determine whether the observed correspondence remains when PTSD symptoms significantly decline.

Skin conductance response to trauma interview as a candidate biomarker of trauma and related psychopathology in youth resettled as refugees

Background: Posttraumatic stress symptoms (PTSS) include a constellation of physical and emotional profiles that youth exposed to trauma may experience. An estimated 20% of youth are exposed to trauma, and in refugee populations, up to 54% experience posttraumatic stress. Given the physical and mental health consequences associated with trauma exposure and subsequent psychopathology, identifying biomarkers of symptom severity is a top research priority. Objective: Previous research in adults found that skin conductance responses to trauma interview predicted current and future PTSS. We extended this method to refugee youth exposed to civilian war trauma and forced migration, to examine associations between PTSS and skin conductance in this uniquely vulnerable child and adolescent population. Methods: 86 refugee youth ages 7-17 years completed a trauma interview and assessment of self-reported PTSS. The mobile eSense app on a iPad was used to obtain continuous recordings of skin conductance level (SCL) during a trauma interview (trauma SCL). Skin conductance response (SCR) was calculated by subtracting the baseline SCL from the maximum amplitude of the trauma SCL. Results: SCL during trauma was significantly greater than baseline SCL, Trauma exposure was significantly associated with SCR to trauma interview, R²= .084, p = .042. SCR to trauma interview was positively correlated with reexperiencing (R² = .127, p = .028), and hyperarousal symptoms (R ²= .123, p = .048). Conclusions: The present study provides evidence for feasibility of SCR to trauma interview as a candidate biomarker of PTSS in youth. This is the first study to look at SCR to trauma interview in youth resettled as refugees and is part of the limited but growing body of research to look at biomarkers in refugee cohorts more broadly. As the number of forcibly displaced persons surges, early detection and prevention of trauma-related psychology is becoming more important than ever.

HIGHLIGHTS

Using the mobile eSense app, we demonstrate that skin conductance is measurable in a variety of research settings and that skin conductance response may be a biological indicator of trauma and related psychopathology - namely re-experiencing symptoms - in youth resettled as refugees.

Cardiorespiratory fitness as protection against the development of memory intrusions: A prospective trauma analogue study

Intrusive and distressing memories are at the core of post-traumatic stress disorder (PTSD). Since cardiorespiratory fitness (CRF) has been linked with improved mental health, emotion regulation, and memory function, CRF may, by promoting these capabilities, protect against the development of intrusions after trauma. We investigated the CRF-intrusion relationship and its potential mediators in 115 healthy individuals, using a trauma film to induce intrusions. As potential mediators, we assessed indices of pre-trauma mental health such as heart rate variability, subjective and psychobiological peri-traumatic responses, and memory. Critically, results showed that higher CRF was related to fewer intrusions, but no mediators emerged for the CRF-intrusion relationship. These results indicate that individuals displaying higher CRF are less prone to develop traumatic memory intrusions. Future studies may want to investigate whether promoting fitness prior to possible trauma exposure can boost resilience against the development of debilitating re-experiencing symptoms of PTSD.

Autonomic dysfunction in posttraumatic stress disorder indexed by heart rate variability: a meta-analysis

BACKGROUND

Changes in autonomic nervous system (ANS) function have been observed in a variety of psychological disorders, including posttraumatic stress disorder (PTSD). Analysis of heart rate variability (HRV) provides insight into the functioning of the ANS. Previous research on PTSD found lower HRV in PTSD patients compared to controls, indicating altered sympathetic and parasympathetic activity, but findings are inconsistent. The purpose of this meta-analysis was to examine differences in HRV indices between individuals with PTSD and healthy controls at baseline and during stress.

METHODS

The included primary studies present an aggregate of studies analyzing different HRV indices. Examined HRV indices were standard deviation of the normalized NN-intervals (SDNN), root mean square of successive differences (RMSSD), low-frequency (LF) and high-frequency (HF) spectral components, LF/HF ratio, and heart rate (HR). Moderating effects of study design, HRV and PTSD assessment, and sample characteristics were examined via subgroup-analyses and meta-regressions.

RESULTS

Random-effects meta-analyses for HRV parameters at rest revealed significant group differences for RMSSD and HF-HRV, suggesting lower parasympathetic activity in PTSD. The aggregated effect size for SDNN was medium, suggesting diminished total variability in PTSD. A small effect was found for LF-HRV. A higher LF/HF ratio was found in the PTSD sample as compared to controls. Individuals with PTSD showed significantly higher HR. During stress, individuals with PTSD showed higher HR and lower HF-HRV, both indicated by small effect sizes.

CONCLUSIONS

Findings suggest that PTSD is associated with ANS dysfunction.

Intrusive memories of trauma: A target for research bridging cognitive science and its clinical application

Intrusive memories of a traumatic event can be distressing and disruptive, and comprise a core clinical feature of post-traumatic stress disorder (PTSD). Intrusive memories involve mental imagery-based impressions that intrude into mind involuntarily, and are emotional. Here we consider how recent advances in cognitive science have fueled our understanding of the development and possible treatment of intrusive memories of trauma. We conducted a systematic literature search in PubMed, selecting articles published from 2008 to 2018 that used the terms "trauma" AND ("intrusive memories" OR "involuntary memories") in their abstract or title. First, we discuss studies that investigated internal (neural, hormonal, psychophysiological, and cognitive) processes that contribute to intrusive memory development. Second, we discuss studies that targeted these processes using behavioural/pharmacological interventions to reduce intrusive memories. Third, we consider possible clinical implications of this work and highlight some emerging research avenues for treatment and prevention, supplemented by new data to examine some unanswered questions. In conclusion, we raise the possibility that intrusive memories comprise an alternative, possibly more focused, target in translational research endeavours, rather than only targeting overall symptoms of disorders such as PTSD. If so, relatively simple approaches could help to address the need for easy-to-deliver, widely-scalable trauma interventions.

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.