Sympathetic Nervous System Responses Research Articles

Estimation of Pressure Pain in the Lower Limbs Using Electrodermal Activity, Tissue Oxygen Saturation, and Heart Rate Variability

Quantification of pain or discomfort induced by pressure is essential for understanding human responses to physical stimuli and improving user interfaces. Pain research has been conducted to investigate physiological signals associated with discomfort and pain perception. This study analyzed changes in electrodermal activity (EDA), tissue oxygen saturation (StO2), heart rate variability (HRV), and Visual Analog Scale (VAS) under pressures of 10, 20, and 30 kPa applied for 3 min to the thigh, knee, and calf in a seated position. Twenty participants were tested, and relationships between biosignals, pressure intensity, and pain levels were evaluated using Friedman tests and post-hoc analyses. Multiple linear regression models were used to predict VAS and pressure, and five machine learning models (SVM, Logistic Regression, Random Forest, MLP, KNN) were applied to classify pain levels (no pain: VAS 0, low: VAS 1–3, moderate: VAS 4–6, high: VAS 7–10) and pressure intensity. The results showed that higher pressure intensity and pain levels affected sympathetic nervous system responses and tissue oxygen saturation. Most EDA features and StO2 significantly changed according to pressure intensity and pain levels, while NN interval and HF among HRV features showed significant differences based on pressure intensity or pain level. Regression analysis combining biosignal features achieved a maximum R2 of 0.668 in predicting VAS and pressure intensity. The four-level classification model reached an accuracy of 88.2% for pain levels and 81.3% for pressure intensity. These results demonstrated the potential of EDA, StO2, HRV signals, and combinations of biosignal features for pain quantification and prediction.

Electrophisiological monitoring of pain in non-communicative critically ill patients.

Electrophysiological monitoring of pain provides objective measures that allow for pain control and adjustment of analgesia in non-communicative patients. Among the available electrophysiological devices, automated infrared pupillometry, Analgesia Nociception Index (ANI), and Nociception Level Index (NOL®) stand out. These non-invasive measurement systems analyze the sympathetic or parasympathetic nervous system response to painful stimuli by observing pupillary dilatation and reactivity (pupillometry), heart rate during respiration (ANI), or a combination of multiple parameters from the nociceptive-autonomic medullary circuit (NOL®). These methods have mainly been used in the monitoring of nociception related to procedures in critically ill patients. Furthermore, they have allowed for the prediction, adjustment, and customization of analgesia administration prior to painful procedures. To obtain accurate measurements and properly interpret the values provided by these devices, it is important to consider certain limitations in their use, such as the administration of specific medications or the presence of certain pathologies, due to their influence on the autonomic nervous system response. It is also important to note that the reported level of evidence is limited, as randomized clinical trials in the context of intensive care unit regarding these devices are currently lacking.

Effects of Transcranial Electrical Stimulation on Physiological Responses to Acute Stress: A Systematic Review

AbstractPhysiological responses to acute stress generally proceed through two phases: first, a rapid and transient sympathetic and parasympathetic nervous system response, and second, a slow and relatively sustained hypothalamic-pituitary-adrenal (HPA) response. These responses are associated with changes in heart rate, heart rate variability, electrodermal responses, blood pressure, and salivary biomarkers such as alpha amylase and cortisol. Through the interactions of biochemical responses to stress and distributed brain regions including the amygdala, hippocampus, striatum, and prefrontal cortex, acute stress exposure can also adversely affect cognitive function. Transcranial electrical stimulation (tES), including transcranial direct, alternating, and random noise stimulation (tDCS, tACS, tRNS), has been examined for its potential ability to modulate physiological responses to stress and buffer negative impacts of stress on cognitive function. This systematic review surveyed research examining the effects of tES on physiological responses to acute stress in healthy neurotypical samples, examining cardiorespiratory (e.g., blood pressure, heart rate), peripheral (e.g., electrodermal), and biochemical (e.g., alpha amylase, salivary cortisol) outcomes. Sixteen reports were identified for inclusion. The articles showed low to high risk of bias, used a diverse set of acute stress induction techniques and tES methodologies, and examined a wide range of physiological outcomes. We found mixed evidence for the effectiveness of tES in reducing acute stress responses, and suggest that some tES methodologies may be more promising than others. Several directions for continuing research are proposed to help elucidate the mechanisms underlying tES effects on acute stress responses and clarify its potential for application to cognitive enhancement domains.

Childhood Maltreatment and Electrodermal Reactivity to Stress Among Pregnant Women.

There are competing theoretical hypotheses regarding the consequences of early adversity, such as childhood maltreatment, for individuals' autonomic nervous system activity. Research examining potential implications of child maltreatment for sympathetic nervous system activity, specifically, is scarce. In this preregistered study, we examined whether childhood maltreatment history is associated with pregnant adults' sympathetic responses to different stressors. This population is particularly relevant, given potential intergenerational consequences of pregnant individuals' physiological responses to stress. Pregnant women's (N=162) electrodermal levels were recorded while completing the Trier Social Stress Test (TSST), which elicits social-evaluative threat, and while watching a video of an unfamiliar infant crying, which was intended to activate the attachment system. Pregnant women's retrospective reports of childhood maltreatment were negatively associated with their electrodermal reactivity to the TSST and to the video of the infant crying. Follow-up analyses indicated that these associations were specific to reported experiences of childhood abuse and not childhood neglect. Altogether, these findings indicate that self-reported childhood maltreatment experiences, and childhood abuse in particular, may result in blunted activity of the sympathetic nervous system in response to multiple types of stressors.

Examining hypothalamic-pituitary-adrenal axis genetic variation on cortisol and alpha-amylase reactivity during an explicit negative-evaluative stress induction.

Prior work consistently links additive genetic variation in the hypothalamic-pituitary-adrenal (HPA) axis-a multilocus genetic profile score (MGPS)-to depression risk in the context of stress exposure. However, despite that HPA MGPS variants were selected based on evidence that they elevate cortisol reactivity, there are surprisingly few tests of whether an HPA MGPS elevates cortisol reactivity to lab-based stress. Similarly, despite neurobiological connections and coordination between the HPA axis and the sympathetic nervous system (e.g., in the paraventricular nucleus and locus coeruleus), no work has tested whether an HPA MGPS influences sympathetic nervous system reactivity to stress. We investigated whether an HPA MGPS moderates the relation between lab-based stress and: (1) HPA activity indexed by cortisol, and/or (2) sympathetic activity indexed by salivary alpha-amylase, sAA. Emerging adults (N=152; mean age=19.5, largest subsample 44.4% Black/African American) were randomly assigned to one of two Trier Social Stress Test variations, a non-evaluative control, or an explicitly negative-evaluative condition. Participants provided DNA and repeated saliva samples for sAA and cortisol. The HPA MGPS did not significantly moderate the relationship between stress condition and cortisol or sAA reactivity, respectively; moreover, post-hoc tests highlight that individual polymorphisms showed non-significant effects in opposite directions from each other, cancelling out in aggregate. Findings suggest that the HPA MGPS's associations with cortisol reactivity are not as straightforward as initially believed. We speculate that the relationships of some HPA variants to biomarker reactivity may vary between modest lab-based stressors and the explicit negative-evaluative induction used here.

Persistence of post-stress blood pressure elevation requires activation of astrocytes

The reflexive excitation of the sympathetic nervous system in response to psychological stress leads to elevated blood pressure, a condition that persists even after the stress has been alleviated. This sustained increase in blood pressure, which may contribute to the pathophysiology of hypertension, could be linked to neural plasticity in sympathetic nervous activity. Given the critical role of astrocytes in various forms of neural plasticity, we investigated their involvement in maintaining elevated blood pressure during the post-stress phase. Specifically, we examined the effects of arundic acid, an astrocytic inhibitor, on blood pressure and heart rate responses to air-jet stress. First, we confirmed that the inhibitory effect of arundic acid is specific to astrocytes. Using c-Fos immunohistology, we then observed that psychological stress activates neurons in cardiovascular brain regions, and that this stress-induced neuronal activation was suppressed by arundic acid pre-treatment in rats. By evaluating astrocytic process thickness, we also confirmed that astrocytes in the cardiovascular brain regions were activated by stress, and this activation was blocked by arundic acid pre-treatment. Next, we conducted blood pressure measurements on unanesthetized, unrestrained rats. Air-jet stress elevated blood pressure, which remained high for a significant period during the post-stress phase. However, pre-treatment with arundic acid, which inhibited astrocytic activation, suppressed stress-induced blood pressure elevation both during and after stress. In contrast, arundic acid had no significant impact on heart rate. These findings suggest that both neurons and astrocytes play integral roles in stress-induced blood pressure elevation and its persistence after stress, offering new insights into the pathophysiological mechanisms underlying hypertension.

Sympathetic response following unannounced loss of balance during walking in young adults: laboratory study.

An unannounced balance loss during walking, i.e., balance perturbation, is a stressful event, which changes the activity of the sympathetic nervous system (SNS). We examined SNS response to unannounced balance perturbation during walking, simulating real-life condition of balance loss. We asked: do laboratory-induced unannounced balance losses during walking cause a sympathetic response, and-if so-does it habituate after a series of perturbations? Thirty-four young adults underwent a series of six successive unannounced balance perturbations while walking on a treadmill. Sympathetic activity was monitored continuously using electrodermal activity and compared before and immediately after each unannounced perturbation. All perturbations elicited a significant increase of electrodermal activity (P < 0.001), indicating a phasic increase in the sympathetic drive. The relative phasic increase of electrodermal activity caused by the first perturbation was significantly higher than the last perturbation (P < 0.05). Three different types of electrodermal activity behavior were observed: steady-level tonic SNS activity, increased SNS activity, and decreased SNS activity. Balance loss during walking triggers phasic SNS response, this response habituates after a series of unannounced balance perturbations. In addition, three distinct patterns of tonic sympathetic activity may imply variations in the ability of the SNS response to habituate across individuals.NEW & NOTEWORTHY Up to date, the literature typically provides information about sympathetic nervous system activity and relatively static balance. We believe that exposing participants to a balance loss during walking, i.e., unexpected perturbation, provides a more ecologically valid situation to measure sympathetic nervous system response; this provides new and vital knowledge that can have a significant impact and understanding of how the SNS responds to a loss of balance in a real-life situation.

Behavioral therapy in migraine: Expanding the therapeutic arsenal.

The US Headache Consortium developed evidence-based guidelines for the treatment of migraine and found grade A evidence in support of behavior therapy (BT). Understanding the mechanisms of BT may improve the management of migraine and reduce its burden. We performed a narrative review to define the current evidence of BT and determine its usefulness in migraine management. The information was obtained from 116 publications, with 56 of them retrieved through direct searches in PubMed (2011-2020) and the remainder selected by the authors to complete the content. BT might reduce migraine impact by decreasing the sympathetic nervous system's response to stress and increasing pain tolerance. Acting in headache-related surroundings can be improved, together with headache duration and self-efficacy. Applications such as mobile health and electronic health applications can help to carry out healthier lifestyle patterns. Regarding medication overuse, BT seems to be a good choice, with similar results to pharmacological prophylaxis. Advantages of using BT are the lack of adverse effects and the unrestricted use in children, where BT is postulated to be even more effective than the standardized pharmacopeia. BT is an interesting tool that can be used as an add-on therapy in migraine. Through BT, the autonomy and empowerment of migraine patients is enhanced. BT may not cure migraine, but it could help to reduce pain severity perception, disability, and migraine impact, adding an emotive and cognitive approach to the perceptive role of pharmacopeia. Thus, a better approach in migraine, implementing specific therapeutic management, can improve migraine control.

Elevated unanticipated acoustic startle reactivity in dyslexia.

People with dyslexia, a neurodevelopmental disorder of reading, are highly attuned to the emotional world. Compared with their typically developing peers, children with dyslexia exhibit greater autonomic nervous system reactivity and facial behaviour to emotion- and empathy-inducing film clips. Affective symptoms, such as anxiety, are also more common in children with dyslexia than in those without. Here, we investigated whether the startle response, an automatic reaction that lies at the interface of emotion and reflex, is elevated in dyslexia. We measured facial behaviour, electrodermal reactivity (a sympathetic nervous system measure) and emotional experience in response to a 100 ms, 105 dB unanticipated acoustic startle task in 30 children with dyslexia and 20 comparison children without dyslexia (aged 7-13) who were matched on age, sex and nonverbal reasoning. Our results indicated that the children with dyslexia had greater total facial behaviour and electrodermal reactivity to the acoustic startle task than the children without dyslexia. Across the sample, greater electrodermal reactivity during the startle predicted greater parent-reported anxiety symptoms. These findings contribute to an emerging picture of heightened emotional reactivity in dyslexia and suggest accentuated sympathetic nervous system reactivity may contribute to the elevated anxiety that is often seen in this population.

Mindfulness-Based Stress Reduction and Autonomic Modulation in Chronic Kidney Disease

Intro: Chronic kidney disease (CKD) is characterized by chronic overactivation of the sympathetic nervous system (SNS) that leads to increased blood pressure and cardiovascular disease risk. Mindfulness-Based Stress Reduction (MBSR) is an 8-week mindfulness meditation training program that has previously been shown to reduce blood pressure and improve autonomic balance in healthy and some clinical populations; however, MBSR has never previously been tested in CKD and the long-term effects of mindfulness mediation on SNS activity are unknown. Thus, we tested the hypothesis that 8 weeks of MBSR reduces SNS activity and reactivity in CKD patients. Method: In a randomized controlled trial, participants with CKD stages III-IV were randomized to 8 weeks of MBSR (n=17, 64±8 yr, 88% males) or a health education program (HEP, n=12, 63±10 yr, 83% males) that served as the active control intervention. MBSR was comprised of eight 2.5-hour group meetings and a retreat session focused on mindfulness training. HEP was administered in a similar structure and focused on health education. Direct intraneural measures of SNS activity directed to muscle (MSNA) was recorded via microneurography with concomitant beat-to-beat blood pressure and EKG monitoring at rest and during mental stress before and after the 8-week intervention. MSNA reactivity during mental arithmetic-induced stress (3 minutes) was compared between baseline and end of study (EOS) in the MBSR and HEP groups. Results. Baseline characteristics, kidney function, and comorbidities were comparable between groups. There was a significant Group (MBSR vs. HEP) by Time (baseline vs. EOS) interaction in the change in MSNA reactivity to mental stress. The MBSR group had a significant reduction in MSNA reactivity during the 1st, 2nd and 3rd minute of mental arithmetic at EOS (p&lt;0.05 for all), while no change was observed within the HEP group. Resting MSNA and reactivity in blood pressure and heart rate during mental arithmetic remained unchanged in both groups from baseline to EOS. Conclusion. Patients with CKD had an amelioration of sympathetic reactivity during mental stress following 8-weeks of MBSR but not after HEP (control intervention). Our findings demonstrate that mindfulness training is feasible and may have potential beneficial effects on autonomic function in CKD. NIH R01HL135183; NIH R61AT10457; NIH KL2TR002381; VA Merit I01CX001065. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Salt-Sensitive Hypertension and the Kidney.

Salt-sensitive hypertension (SS-HT) is characterized by blood pressure elevation in response to high dietary salt intake and is considered to increase the risk of cardiovascular and renal morbidity. Although the mechanisms responsible for SS-HT are complex, the kidneys are known to play a central role in the development of SS-HT and the salt sensitivity of blood pressure (SSBP). Moreover, several factors influence renal function and SSBP, including the renin-angiotensin-aldosterone system, sympathetic nervous system, obesity, and aging. A phenotypic characteristic of SSBP is aberrant activation of the renin-angiotensin system and sympathetic nervous system in response to excessive salt intake. SSBP is also accompanied by a blunted increase in renal blood flow after salt loading, resulting in sodium retention and SS-HT. Obesity is associated with inappropriate activation of the aldosterone mineralocorticoid receptor pathway and renal sympathetic nervous system in response to excessive salt, and mineralocorticoid receptor antagonists and renal denervation attenuate sodium retention and inhibit salt-induced blood pressure elevation in obese dogs and humans. SSBP increases with age, which has been attributed to impaired renal sodium handling and a decline in renal function, even in the absence of kidney disease. Aging-associated changes in renal hemodynamics are accompanied by significant alterations in renal hormone levels and renal sodium handling, resulting in SS-HT. In this review, we focus mainly on the contribution of renal function to the development of SS-HT.

Trauma film viewing and intrusive memories: Relationship between salivary alpha amylase, endocannabinoids, and cortisol

The endogenous cannabinoid (ECB) system is a small molecule lipid signalling system that is involved in stress response activation and is associated with PTSD, but it is unclear whether salivary ECBs are part of the sympathetic nervous system response to stress. We conducted an adapted trauma film paradigm, where participants completed a cold pressor test (or control) while watching a 10-minute trauma film. We also collected saliva and hair samples and tested them for ECBs, cortisol, and salivary alpha amylase (sAA). As hypothesised, there were significant positive correlations between sAA activity and salivary ECB levels, particularly 2-arachidonoyl glycerol (2-AG), though ECBs were not correlated with sAA stress reactivity. Participants who had a significant cortisol response to the trauma film/stressor reported less intrusive memories, which were also less distressing and less vivid. This effect was moderated by arachidonoyl ethanolamide (AEA), where decreases in AEA post-stress were associated with more intrusive memories in cortisol non-responders only. This study provides new evidence for the role of ECBs in the sympathetic nervous system.

Interoceptive beliefs moderate the link between physiological and emotional arousal during an acute stressor.

Growing work suggests that interoception, that is, representations of one's internal bodily changes, plays a role in shaping emotional experiences. Past studies primarily examine how behavioral accuracy in detecting interoceptive signals (interoceptive ability) relates to emotional states, with less work examining self-reported interoceptive facets such as the characterizations of one's interoceptive abilities (interoceptive sensibility) or evaluative beliefs about the value versus danger of interoceptive signals (interoceptive beliefs). However, existing studies rarely examine physiological reactivity, behavioral, and self-reported dimensions of interoception together in the same sample. As such, it remains unclear whether and how much individual differences in interoceptive facets uniquely and in interaction with physiological reactivity may matter for emotional experience. Herein, 250 healthy young adults completed a heartbeat detection task assessing interoceptive ability and questionnaire measures of interoceptive sensibility and beliefs during an initial laboratory visit. At a follow-up session, 227 participants returned to undergo an acute psychosocial stressor. Measures of physiological arousal such as preejection period (PEP) and heart rate variability were acquired throughout the stressor with self-reported emotions acquired immediately after. Linear regressions revealed that greater sympathetic nervous system reactivity (i.e., PEP), poorer interoceptive ability (i.e., accuracy), and less positive interoceptive beliefs were related to more intense high arousal emotions during the stressor. Importantly, across models, interoceptive beliefs was the only interoceptive facet to moderate the concordance between physiological and emotional arousal. Implications for psychological theories of emotion, stress, and interoception are discussed. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Targeted ablation of the left middle cervical ganglion prevents ventricular arrhythmias and cardiac injury induced by AMI.

Cardiac sympathetic overactivation is a critical driver in the progression of acute myocardial infarction (AMI). The left middle cervical ganglion (LMCG) is an important extracardiac sympathetic ganglion. However, the regulatory effects of LMCG on AMI have not yet been fully documented. In the present study, we detected that the LMCG was innervated by abundant sympathetic components and exerted an excitatory effect on the cardiac sympathetic nervous system in response to stimulation. In canine models of AMI, targeted ablation of LMCG reduced the sympathetic indexes of heart rate variability and serum norepinephrine, resulting in suppressed cardiac sympathetic activity. Moreover, LMCG ablation could improve ventricular electrophysiological stability, evidenced by the prolonged ventricular effective refractory period, elevated action potential duration, increased ventricular fibrillation threshold, and enhanced connexin43 expression, consequently showing antiarrhythmic effects. Additionally, compared with the control group, myocardial infarction size, circulating cardiac troponin I, and myocardial apoptosis were significantly reduced, accompanied by preserved cardiac function in canines subjected to LMCG ablation. Finally, we performed the left stellate ganglion (LSG) ablation and compared its effects with LMCG destruction. The results indicated that LMCG ablation prevented ventricular electrophysiological instability, cardiac sympathetic activation, and AMI-induced ventricular arrhythmias with similar efficiency as LSG denervation. In conclusion, this study demonstrated that LMCG ablation suppressed cardiac sympathetic activity, stabilized ventricular electrophysiological properties and mitigated cardiomyocyte death, resultantly preventing ischemia-induced ventricular arrhythmias, myocardial injury, and cardiac dysfunction. Neuromodulation therapytargeting LMCG represented a promising strategy for the treatment of AMI.

Interoceptive ability moderates the effect of physiological reactivity on social judgment.

Social judgments-that others are kind or cruel, well intentioned, or conniving-can ease or disrupt social interactions. And yet a person's internal state can alter these judgments-a phenomenon known as affective realism. We examined the factors that contribute to, and mitigate, affective realism during a stressful interview. Using data collected between 2015 and 2019, we hypothesized and found that individuals' ability (N = 161; 57.6% female; 57.6% European American, 13.6% African American, 13.6% Asian American, 6.4% Latinx, 6.0% biracial, and 2.8% that identified with none or 1 + of the races presented; Mage = 19.20 years) to accurately perceive their own internal sensations (i.e., heartbeats) influenced whether they attributed their own heightened stress reactions (i.e., sympathetic nervous system reactivity) to the behavior of two impassive interviewers. Participants who were poor heartbeat detectors perceived their interviewers as less helpful, polite, or professional, and more apathetic, judgmental, and aggressive when experiencing heightened levels of cardiovascular sympathetic nervous system reactivity during their interview. Being aware of one's internal state may be one pathway to reducing bias in social perceptions in circumstances where such biases may lead us astray. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Sympathetic nervous system responses during complex walking tasks and community ambulation post-stroke

Stroke survivors frequently report increased perceived challenge of walking (PCW) in complex environments, restricting their daily ambulation. PCW is conventionally measured through subjective questionnaires or, more recently, through objective quantification of sympathetic nervous system activity during walking tasks. However, how these measurements of PCW reflect daily walking activity post-stroke is unknown. We aimed to compare the subjective and objective assessments of PCW in predicting home and community ambulation. In 29 participants post-stroke, we measured PCW subjectively with the Activities-specific Balance Confidence (ABC) Scale and objectively through electrodermal activity, quantified by change in skin conductance levels (SCL) and skin conductance responses (SCR) between outdoor-complex and indoor-steady-state walking. High-PCW participants were categorized into high-change SCL (ΔSCL ≥ 1.7 μs), high-change SCR (ΔSCR ≥ 0.2 μs) and low ABC (ABC < 72%) groups, while low-PCW participants were categorized into low-change SCL (ΔSCL < 1.7 μs), low-change SCR (ΔSCR < 0.2 μs) and high-ABC (ABC ≥ 72%) groups. Number and location of daily steps were quantified with accelerometry and Global Positioning System devices. Compared to low-change SCL group, the high-change SCL group took fewer steps in home and community (p = 0.04). Neither ABC nor SCR groups differed in home or community steps/day. Objective measurement of PCW via electrodermal sensing more accurately represents home and community ambulation compared to the subjective questionnaire.

Psychologically aggressive parenting and later aggression: Salivary alpha-amylase reactivity and sex as moderators

Psychologically aggressive parenting (PAP) exposure negatively affects children's development of aggression. Nevertheless, not all children exposed to PAP display aggressive behaviors. Sympathetic nervous system (SNS) activity may influence the impact of early adversity on aggression. This study examines whether SNS reactivity and sex moderate the link between psychologically aggressive parenting (PAP) during childhood and later aggression. Emerging adults (N = 182, mean age = 19.03 years, 53 % female) retrospectively reported on their childhood PAP and current aggression. Salivary alpha-amylase (sAA) collected from a social stress task indexed SNS reactivity to stress. Childhood PAP was associated with emerging adulthood anger, hostility, physical, and verbal aggression. Moreover, males were more likely to exhibit anger, verbal, and physical aggression and had higher levels of sAA reactivity than females. A significant three-way interaction between childhood PAP, sAA reactivity, and sex accounted for participants' current verbal aggression. The link between childhood PAP and later verbal aggression was stronger for males at higher levels of sAA reactivity. Females with higher levels of sAA reactivity displayed lower levels of verbal aggression regardless of PAP exposure. Males and females with lower levels of sAA reactivity were at elevated risk for verbal aggression regardless of PAP exposure. Moreover, we found a significant two-way interaction between PAP and sex on anger, such that higher levels of PAP exposure were associated with more anger among males, but not females. These findings highlight the importance of examining interactions between biological and environmental factors and sex in accounting for later aggression.

Sympathetic nervous system responses to acute psychosocial stress in male physicians with clinical burnout

BackgroundOccupational burnout has been associated with an increased risk of cardiovascular disease, with sympathetic nervous system (SNS) dysfunction as one explanation. This study examined the effects of burnout on responses of SNS activity measures to acute psychosocial stress in male physicians, a population at risk for burnout. MethodsStudy participants were 60 male physicians, 30 with clinical burnout, assessed with the Maslach Burnout Inventory, and 30 without burnout (controls). All participants underwent the 15-min Trier Social Stress Test. Heart rate, blood pressure, salivary alpha-amylase, and plasma levels of epinephrine (EPI) and norepinephrine were assessed pre-stress, immediately post-stress, and 15 min and 45 min post-stress. ResultsPhysicians with burnout and controls differed in EPI changes over time, controlling for age, job stress and anxiety symptoms (F (3,147) = 5.18, p = .002 for 'Time by Group' interaction; η2p = .096). Burnout was associated with a smaller increase in EPI from pre-stress to immediately post-stress (r(54) = −.40, p = .004). The emotional exhaustion dimension of burnout was a significant driver of this effect. The area under the curve with respect to increase in EPI was also smaller in the burnout group (F (1,49) = 6.06, p = .017, η2p = .110). Group differences were not significant for the other SNS activity measures. ConclusionsBurnout may be linked to dysfunction of the sympathoadrenal medullary (SAM) system, when exposed to acute psychosocial stress. In keeping with the allostatic load concept, an insufficient SAM stress response in burnout could potentially contribute to cardiovascular disease.

Biological stress responses to multitasking and work interruptions: A randomized controlled trial

In the course of digitalization, new stressors are emerging. In modern working and living environments, two ubiquitous, technology-mediated stressors are multitasking demands and work interruptions. However, biological stress response patterns to multitasking and work interruptions have been sparsely investigated so far. We thus aimed to comprehensively assess biological stress response patterns to both stressors and, additionally, test whether responses differ between digital and partially non-digital settings. A controlled experimental set-up was established and humans’ biological markers of the Sympathetic Nervous System (SNS), the hypothalamic-pituitary adrenal (HPA) axis, and the immune system were assessed. N = 186 healthy participants (mean age: 23.2 ± 4.3 years, 74.7% female, body mass-index: 22.3 ± 3.1 kg/m2) took part in this pre-registered study. Each participant was randomly assigned to one of 6 experimental conditions (1 digital single-task, 3 dual-tasks [2 parallel tasks and 1 interruption], 1 multitasking, and 1 passive, control condition). Each one of the dual-tasking as well as the multitasking conditions included a non-digital sub-task, i.e., performing a task in presence of an examiner. All other conditions involved digital tasks only. Salivary alpha-amylase (sAA) levels as a marker for SNS reactivity significantly changed in work interruptions, parallel dual-tasking, and multitasking conditions. No changes were found for control conditions. Furthermore, no significant changes over time and no differences between the conditions were identified for three biological markers: cortisol as marker for HPA axis activity as well as for two immune system markers (secretory Immunoglobulin-A, C-reactive protein). A time course similar to sAA was found for perceived stress: with increases during task execution and decreases afterwards in multitasking and parallel dual-tasking. Yet, it did not change for the work interruption, passive control, and single-tasking condition. Overall, our findings show that dual- and multitasking are perceived as stressful and are associated with an activation of the SNS, but not with responses of HPA axis or immune system. This was consistent for digital as well as partially digital task demands. Our findings will also inform future research into the differential stress effects of digital and non-digital tasks to advance our understanding of biological stress response-patterns to multitasking and work interruptions. Therefore, our findings are highly relevant for understanding the long-term biological health effects of stress in modern (digitalized) environments.

Reference gene recommendations and PACAP receptor expression in murine sympathetic ganglia of the autonomic nervous system that innervate adipose tissues after chronic cold exposure.

Pituitary adenylate cyclase-activating polypeptide (PACAP) is an important regulator of the stress response in mammals, influencing both the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system (SNS). PACAP has been reported to influence energy homeostasis, including adaptive thermogenesis, an energy burning process in adipose tissue regulated by the SNS in response to cold stress and overfeeding. While research suggests PACAP acts centrally at the level of the hypothalamus, knowledge of PACAP's role within the sympathetic nerves innervating adipose tissues in response to metabolic stressors is limited. This work shows, for the first time, gene expression of PACAP receptors in stellate ganglia and highlights some differential expression with housing temperature. Additionally, we present our dissection protocol, analysis of tyrosine hydroxylase gene expression as a molecular biomarker for catecholamine producing tissue and recommend three stable reference genes for the normalization of quantitative real time-polymerase chain reaction (qRT-PCR) data when working with this tissue. This study adds to information about neuropeptide receptor expression in peripheral ganglia of the sympathetic nervous system innervating adipose tissue and provides insight into PACAP's role in the regulation of energy metabolism.