Methods of evaluation of autonomic nervous system function

Measures of nutrition status and health for weight-inclusive patient care: A narrative review

In healthcare, weight is often equated to and used as a marker for health. In examining nutrition and health status, there are many more effective markers independent of weight. In this article, we review practical and emerging clinical applications of technologies and tools used to collect non-weight-related data in nutrition assessment, monitoring, and evaluation in the outpatient setting. The aim is to provide clinicians with new ideas about various types of data to evaluate and track in nutrition care.

Non-invasive ventral cervical magnetoneurography as a proxy of in vivo lipopolysaccharide-induced inflammation

Maintenance of autonomic homeostasis is continuously calibrated by sensory fibers of the vagus nerve and sympathetic chain that convey compound action potentials (CAPs) to the central nervous system. Lipopolysaccharide (LPS) intravenous challenge reliably elicits a robust inflammatory response that can resemble systemic inflammation and acute endotoxemia. Here, we administered LPS intravenously in nine healthy subjects while recording ventral cervical magnetoneurography (vcMNG)-derived CAPs at the rostral Right Nodose Ganglion (RNG) and the caudal Right Carotid Artery (RCA) with optically pumped magnetometers (OPM). We observed vcMNG RNG and RCA neural firing rates that tracked changes in TNF-α levels in the systemic circulation. Further, endotype subgroups based on high and low IL-6 responders segregate RNG CAP frequency (at 30-120 min) and based on high and low IL-10 response discriminate RCA CAP frequency (at 0-30 min). These vcMNG tools may enhance understanding and management of the neuroimmune axis that can guide personalized treatment based on an individual's distinct endophenotype.

Depressive symptoms as risk factors for the onset of home hypertension: a prospective cohort study

Depression is comorbid with somatic diseases; however, the relationship between depressive symptoms and hypertension (HT), a risk factor for cardiovascular events, remains unclear. Home blood pressure (BP) is more reproducible and accurately predictive of cardiovascular diseases than office BP. Therefore, we focused on home BP and investigated whether depressive symptoms contributed to the future onset of home HT. This prospective cohort study used data from the Tohoku Medical Megabank Community-Cohort Study (conducted in the Miyagi Prefecture, Japan) and included participants with home normotension (systolic blood pressure (SBP) < 135 mmHg and diastolic blood pressure (DBP) < 85 mmHg). Depressive symptoms were evaluated using the Center for Epidemiologic Studies Depression Scale-Japanese version at the baseline survey. In the secondary survey, approximately 4 years later, the onset of home HT was evaluated (SBP ≥ 135 mmHg or DBP ≥ 85 mmHg) and was compared in participants with and without depressive symptoms. Of the 3 082 (mean age: 54.2 years; females: 80.9%) participants, 729 (23.7%) had depressive symptoms at the baseline survey. During the 3.5-year follow-up, 124 (17.0%) and 388 (16.5%) participants with and without depressive symptoms, respectively, developed home HT. Multivariable adjusted odds ratios were 1.37 (95% confidence interval (CI): 1.02-1.84), 1.18 (95% CI: 0.86-1.61), and 1.66 (95% CI: 1.17-2.36) for home, morning, and evening HT, respectively. This relationship was consistent in the subgroup analyses according to age, sex, BP pattern, and drinking habit. Depressive symptoms increased the risk of new-onset home HT, particularly evening HT, among individuals with home normotension. This prospective cohort study revealed that depressive symptoms are risk factors for new-onset home hypertension, particularly evening hypertension among individuals with home normotension. Assessing home blood pressure in individuals with depressive symptoms is important for the prevention of hypertension and concomitant cardiovascular diseases.

Effect of zamicastat on blood pressure and heart rate response to cold pressor test: A double-blind, randomized, placebo-controlled study in healthy subjects

AIMS

Dopamine beta-hydroxylase (DβH) inhibitors, like zamicastat, hold promise for treating pulmonary arterial hypertension. This study aimed to validate the mechanism of action of zamicastat by studying its effect on the overdrive of the sympathetic nervous system (SNS).

METHODS

A single-centre, prospective, double-blind, randomized, placebo-controlled, crossover study evaluated the effect of 400 mg zamicastat in 22 healthy male subjects. Cold pressor test (CPT) was performed at screening and each treatment period on Days -1 and 10. Plasma and 24 h-urine levels of dopamine (DA), epinephrine (EPI) and norepinephrine (NE), and plasma DβH activity, were measured.

RESULTS

Compared to placebo, zamicastat showed a - 4.62 mmHg decrease in systolic blood pressure during the cold stimulus vs. rest phases on Day 10 of CPT (P = .020). Zamicastat decreased mean arterial pressure response to cold stimulus during CPT (-2.62 mmHg; P = .025). At Day 10, zamicastat significantly increased plasma DA, before CPT (12.63 ng/L; P = .040) and after CPT (19.22 ng/L; P = .001) as well as the estimated plasma EPI change from baseline after CPT (P = .040). Inhibition of plasma DβH activity ranged from 19.8% to 25.0%. At Day 10, significant reductions in 24-h urinary excretion of EPI (P = .002) and NE (P = .001) were observed. Zamicastat Cτ geometric mean ± GSD ranged from 45.86 ± 1.46 ng/mL on Day 3 to 58.64 ± 1.52 ng/mL on Day 10, with moderate inter-individual variability (CV: 32.6%-36.6%). Steady state was already achieved on Day 6.

CONCLUSIONS

Our results demonstrated the effect of zamicastat on the overdrive sympathetic response to cold stimulus, confirming its potential as SNS modulator.

Innervation of the coronary arteries and its role in controlling microvascular resistance

The coronary circulation plays a crucial role in balancing myocardial perfusion and oxygen demand to prevent myocardial ischemia. Extravascular compressive forces, coronary perfusion pressure, and microvascular resistance are involved to regulate coronary blood flow throughout the cardiac cycle. Autoregulation of the coronary blood flow through dynamic adjustment of microvascular resistance is maintained by complex interactions among mechanical, endothelial, metabolic, neural, and hormonal mechanisms. This review focuses on the neural mechanism. Anatomy and physiology of the coronary arterial innervation have been extensively investigated using animal models. However, findings in the animal heart have limited applicability to the human heart as cardiac innervation is generally highly variable among species. So far, limited data are available on the human coronary artery innervation, rendering multiple questions unresolved. Recently, the clinical entity of ischemia with non-obstructive coronary arteries has been proposed, characterized by microvascular dysfunction involving abnormal vasoconstriction and impaired vasodilation. Thus, measurement of microvascular resistance has become a standard diagnostic for patients without significant stenosis in the epicardial coronary arteries. Neural mechanism is likely to play a pivotal role, supported by the efficacy of cardiac sympathetic denervation to control symptoms in patients with angina. Therefore, understanding the coronary artery innervation and control of microvascular resistance of the human heart is increasingly important for cardiologists for diagnosis and to select appropriate therapeutic options. Advancement in this field can lead to innovations in diagnostic and therapeutic approaches for coronary artery diseases.

Ultrasound Neuromodulation of an Anti-Inflammatory Pathway at the Spleen Improves Experimental Pulmonary Hypertension

BACKGROUND

Inflammation is pathogenically implicated in pulmonary arterial hypertension; however, it has not been adequately targeted therapeutically. We investigated whether neuromodulation of an anti-inflammatory neuroimmune pathway involving the splenic nerve using noninvasive, focused ultrasound stimulation of the spleen (sFUS) can improve experimental pulmonary hypertension.

METHODS

Pulmonary hypertension was induced in rats either by Sugen 5416 (20 mg/kg SQ) injection, followed by 21 (or 35) days of hypoxia (sugen/hypoxia model), or by monocrotaline (60 mg/kg IP) injection (monocrotaline model). Animals were randomized to receive either 12-minute-long sessions of sFUS daily or sham stimulation for 14 days. Catheterizations, echocardiography, indices of autonomic function, lung and heart histology and immunohistochemistry, spleen flow cytometry, and lung single-cell RNA sequencing were performed after treatment to assess the effects of sFUS.

RESULTS

Splenic denervation right before induction of pulmonary hypertension results in a more severe disease phenotype. In both sugen/hypoxia and monocrotaline models, sFUS treatment reduces right ventricular systolic pressure by 25% to 30% compared with sham treatment, without affecting systemic pressure, and improves right ventricular function and autonomic indices. sFUS reduces wall thickness, apoptosis, and proliferation in small pulmonary arterioles, suppresses CD3+ and CD68+ cell infiltration in lungs and right ventricular fibrosis and hypertrophy and lowers BNP (brain natriuretic peptide). Beneficial effects persist for weeks after sFUS discontinuation and are more robust with early and longer treatment. Splenic denervation abolishes sFUS therapeutic benefits. sFUS partially normalizes CD68+ and CD8+ T-cell counts in the spleen and downregulates several inflammatory genes and pathways in nonclassical and classical monocytes and macrophages in the lung. Differentially expressed genes in those cell types are significantly enriched for human pulmonary arterial hypertension-associated genes.

CONCLUSIONS

sFUS causes dose-dependent, sustained improvement of hemodynamic, autonomic, laboratory, and pathological manifestations in 2 models of experimental pulmonary hypertension. Mechanistically, sFUS normalizes immune cell populations in the spleen and downregulates inflammatory genes and pathways in the lung, many of which are relevant in human disease.

Cardiovascular Autonomic Dysfunction in Hospitalized Patients with a Bacterial Infection: A Longitudinal Observational Pilot Study in the UK

PURPOSE

A temporal reduction in the cardiovascular autonomic responses predisposes patients to cardiovascular instability after a viral infection and therefore increases the risk of associated complications. These findings have not been replicated in a bacterial infection. This pilot study will explore the prevalence of cardiovascular autonomic dysfunction (CAD) in hospitalized patients with a bacterial infection.

METHODS

A longitudinal observational pilot study was conducted. Fifty participants were included: 13 and 37 participants in the infection group and healthy group, respectively. Recruitment and data collection were carried out during a two-year period. Participants were followed up for 6 weeks: all participants' cardiovascular function was assessed at baseline (week 1) and reassessed subsequently at week 6 so that the progression of the autonomic function could be evaluated over that period of time. The collected data were thereafter analyzed using STATA/SE version 16.1 (StataCorp). The Fisher Exact test, McNemar exact test, Mann-Whitney test and Wilcoxon test were used for data analysis.

RESULTS

32.4% of the participants in the healthy group were males (n = 12) and 67.6% were females (n = 25). Participants' age ranged from 33 years old to 76 years old with the majority being 40-60 years of age (62.1%) (Mean age 52.4 SD = 11.4). Heart rate variability (HRV) in response to Valsalva Maneuver, metronome breathing, standing and sustained handgrip in the infection group was lower than in the healthy group throughout the weeks. Moreover, both the HRV in response to metronome breathing and standing up showed a statistically significant difference when the mean values were compared between both groups in week 1 (p = 0.03 and p = 0.013). The prevalence of CAD was significantly higher in the infection group compared to healthy volunteers, both at the beginning of the study (p = 0.018) and at the end of follow up (p = 0.057), when all patients had been discharged.

CONCLUSIONS

CAD, as assessed by the HRV, is a common finding during the recovery period of a bacterial infection, even after 6 weeks post-hospital admission. This may increase the risk of complications and cardiovascular instability. It may therefore be of value to conduct a wider scale study to further evaluate this aspect so recommendations can be made for the cardiovascular autonomic assessment of patients while they are recovering from a bacterial infectious process.

Maternal childhood emotional abuse increases cardiovascular responses to children's emotional facial expressions

Parents with a history of childhood maltreatment may be more likely to respond inadequately to their child's emotional cues, such as crying or screaming, due to previous exposure to prolonged stress. While studies have investigated parents' physiological reactions to their children's vocal expressions of emotions, less attention has been given to their responses when perceiving children's facial expressions of emotions. The present study aimed to determine if viewing facial expressions of emotions in children induces cardiovascular changes in mothers (hypo- or hyper-arousal) and whether these differ as a function of childhood maltreatment. A total of 104 mothers took part in this study. Their experiences of childhood maltreatment were measured using the Childhood Trauma Questionnaire (CTQ). Participants' electrocardiogram signals were recorded during a task in which they viewed a landscape video (baseline) and images of children's faces expressing different intensities of emotion. Heart rate variability (HRV) was extracted from the recordings as an indicator of parasympathetic reactivity. Participants presented two profiles: one group of mothers had a decreased HRV when presented with images of children's facial expressions of emotions, while the other group's HRV increased. However, HRV change was not significantly different between the two groups. The interaction between HRV groups and the severity of maltreatment experienced was marginal. Results suggested that experiences of childhood emotional abuse were more common in mothers whose HRV increased during the task. Therefore, more severe childhood experiences of emotional abuse could be associated with mothers' cardiovascular hyperreactivity. Maladaptive cardiovascular responses could have a ripple effect, influencing how mothers react to their children's facial expressions of emotions. That reaction could affect the quality of their interaction with their child. Providing interventions that help parents regulate their physiological and behavioral responses to stress might be helpful, especially if they have experienced childhood maltreatment.

Parasympathetic neurons derived from human pluripotent stem cells model human diseases and development

Autonomic parasympathetic neurons (parasymNs) control unconscious body responses, including "rest-and-digest." ParasymN innervation is important for organ development, and parasymN dysfunction is a hallmark of autonomic neuropathy. However, parasymN function and dysfunction in humans are vastly understudied due to the lack of a model system. Human pluripotent stem cell (hPSC)-derived neurons can fill this void as a versatile platform. Here, we developed a differentiation paradigm detailing the derivation of functional human parasymNs from Schwann cell progenitors. We employ these neurons (1) to assess human autonomic nervous system (ANS) development, (2) to model neuropathy in the genetic disorder familial dysautonomia (FD), (3) to show parasymN dysfunction during SARS-CoV-2 infection, (4) to model the autoimmune disease Sjögren's syndrome (SS), and (5) to show that parasymNs innervate white adipocytes (WATs) during development and promote WAT maturation. Our model system could become instrumental for future disease modeling and drug discovery studies, as well as for human developmental studies.

Normal baseline cardiac autonomic function and increased pupillary parasympathetic tone in patients with vasovagal syncope

It is controversial whether people with vasovagal syncope (VVS) have abnormal autonomic responses at baseline and whether specific diagnostic manoeuvres have a diagnostic value. We investigated whether the pupillary light reflex and cardiac autonomic tests can be used to identify autonomic dysfunction in volunteers with a medical history of VVS. The study groups included 128 healthy volunteers, of whom 31 reported a history of typical VVS. The right pupil was evaluated using an automated, commercial infra-red pupillometer under strict conditions. In addition to miosis and mydriasis kinetics, pupil diameters were measured. Heart rate variability at rest and heart rate changes to standing were quantified with high-resolution electrocardiography and designated software. The demographic and clinical characteristics of both groups were statistically similar. Average constriction velocity (ACV) was significantly higher in VVS patients following a univariate analysis (3.83 ± 0.59 vs. 3.56 ± 0.73 mm/s, p = 0.042) and after correcting for potential confounders (p = 0.049). All other pupillometric and heart rate indices were comparable between groups. Patients with a history of VVS depict pupillary parasympathetic overactivity in response to light stimuli, manifested as increased ACV. The prognostic implications of this finding and the significance of using this simple clinical tool to identify patients who are at risk for developing frequent episodes of VVS or physical injuries following a syncope merits further study.

How to properly evaluate cardiac vagal tone in oncology studies: a state-of-the-art review

Heart rate variability (HRV) analysis provides an assessment of cardiac vagal tone and consequently global cardiac health as well as systemic condition. In systemic diseases such as cancer and during treatments that affect the whole body, like chemotherapy, the vagus nerve activity is low and deregulated. Some studies focus on using HRV to predict mortality in oncology. However, in cancer patients, systemic alterations substantially increase artifacts during HRV measurement, especially atrial ectopic beats. Moreover, HRV may be altered by various factors (duration and time of measurement, breathing, drugs, and other confounding factors) that alter each metric in different ways. The Standard Deviation of all Normal to Normal intervals (SDNN) is the most commonly used metric to evaluate HRV in oncology, but it does not appear to be specific to the cardiac vagal tone. Thus, cardiac vagal activity diagnosis and vital prognosis of cancer patients can be biased. Our review presents the main HRV metrics that can be currently used in oncology studies and their links with vagus nerve and cancer. We present the influence of external factors and the required duration and time of measurement. Considering all these parameters, this review proposes seven key points for an assessment of HRV and cardiac vagal tone in patients with cancer.

Household food insecurity is associated with greater autonomic dysfunction testing score in Latinos with type 2 diabetes

AIM

We examined household food insecurity (HFI) and autonomic nervous system (ANS) function in a subset of low-income Latinos with type 2 diabetes with data from a stress management trial.

METHODS

InclusionLatino or Hispanic, Spanish speaking, age less than 18 years, ambulatory status, type 2 diabetes more than 6 months, A1c less than 7.0%. ExclusionPain or dysfunction in hands (e.g., arthritis) precluding handgrip testing; medical or psychiatric instability. HFI was assessed with the 6-item U.S. household food security survey module; with responses to > = 1 question considered HFI. An ANS dysfunction index was calculated from xix autonomic function tests which were scored 0 = normal or 1 = abnormal based on normative cutoffs and then summed. Autonomic function tests were: 1) 24-hour heart rate variability as reflected in standard deviation of the normal-to-normal (SDNN) heart rate acquired with 3-channel, 7-lead ambulatory electrocardiogram (Holter) monitors; 2) difference between the highest diastolic blood pressure (DBP) during sustained handgrip and the average DBP at rest; 3) difference between baseline supine and the minimal BP after standing up; and, from 24-hour urine specimens 4) cortisol, 5) normetanephrine, and, 6) metanephrine.

RESULTS

Thirty-five individuals participated, 23 (65.7%) of them were women, age mean = 61.6 (standard deviation = 11.2) years, HbA1c mean = 8.5% (standard deviation = 1.6) and 20 participants (57.1%) used insulin. Twenty-two participants (62.9%) reported HFI and 25 (71.4%) had one or more abnormal ANS measure. Independent t-tests showed that participants with HFI had a higher ANS dysfunction index (mean = 1.5, standard deviation = 0.9) than patients who were food secure (mean = 0.7, standard deviation = 0.8), p = 0.02. Controlling for financial strain did not change significance. Total ANS index was not related to glycemia, insulin use or other socioeconomic indicators. In this sample, HFI was associated with ANS dysfunction. Policies to improve food access and affordability may benefit health outcomes for Latinos with diabetes.

Non-invasive parameters of autonomic function using beat-to-beat cardiovascular variations and arterial stiffness in hypertensive individuals: a systematic review

PURPOSE

Non-invasive, beat-to-beat variations in physiological indices provide an opportunity for more accessible assessment of autonomic dysfunction. The potential association between the changes in these parameters and arterial stiffness in hypertension remains poorly understood. This systematic review aims to investigate the association between non-invasive indicators of autonomic function based on beat-to-beat cardiovascular signals with arterial stiffness in individuals with hypertension.

METHODS

Four electronic databases were searched from inception to June 2022. Studies that investigated non-invasive parameters of arterial stiffness and autonomic function using beat-to-beat cardiovascular signals over a period of > 5min were included. Study quality was assessed using the STROBE criteria. Two authors screened the titles, abstracts, and full texts independently.

RESULTS

Nineteen studies met the inclusion criteria. A comprehensive overview of experimental design for assessing autonomic function in terms of baroreflex sensitivity and beat-to-beat cardiovascular variabilities, as well as arterial stiffness, was presented. Alterations in non-invasive indicators of autonomic function, which included baroreflex sensitivity, beat-to-beat cardiovascular variabilities and hemodynamic changes in response to autonomic challenges, as well as arterial stiffness, were identified in individuals with hypertension. A mixed result was found in terms of the association between non-invasive quantitative autonomic indices and arterial stiffness in hypertensive individuals. Nine out of 12 studies which quantified baroreflex sensitivity revealed a significant association with arterial stiffness parameters. Three studies estimated beat-to-beat heart rate variability and only one study reported a significant relationship with arterial stiffness indices. Three out of five studies which studied beat-to-beat blood pressure variability showed a significant association with arterial structural changes. One study revealed that hemodynamic changes in response to autonomic challenges were significantly correlated with arterial stiffness parameters.

CONCLUSIONS

The current review demonstrated alteration in autonomic function, which encompasses both the sympathetic and parasympathetic modulation of sinus node function and vasomotor tone (derived from beat-to-beat cardiovascular signals) in hypertension, and a significant association between some of these parameters with arterial stiffness. By employing non-invasive measurements to monitor changes in autonomic function and arterial remodeling in individuals with hypertension, we would be able to enhance our ability to identify individuals at high risk of cardiovascular disease. Understanding the intricate relationships among these cardiovascular variability measures and arterial stiffness could contribute toward better individualized treatment for hypertension in the future.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO ID: CRD42022336703. Date of registration: 12/06/2022.

Autonomic dysfunction and treatment strategies in intracerebral hemorrhage

AIMS

Autonomic dysfunction with central autonomic network (CAN) damage occurs frequently after intracerebral hemorrhage (ICH) and contributes to a series of adverse outcomes. This review aims to provide insight and convenience for future clinical practice and research on autonomic dysfunction in ICH patients.

DISCUSSION

We summarize the autonomic dysfunction in ICH from the aspects of potential mechanisms, clinical significance, assessment, and treatment strategies. The CAN structures mainly include insular cortex, anterior cingulate cortex, amygdala, hypothalamus, nucleus of the solitary tract, ventrolateral medulla, dorsal motor nucleus of the vagus, nucleus ambiguus, parabrachial nucleus, and periaqueductal gray. Autonomic dysfunction after ICH is closely associated with neurological functional outcomes, cardiac complications, blood pressure fluctuation, immunosuppression and infection, thermoregulatory dysfunction, hyperglycemia, digestive dysfunction, and urogenital disturbances. Heart rate variability, baroreflex sensitivity, skin sympathetic nerve activity, sympathetic skin response, and plasma catecholamine concentration can be used to assess the autonomic functional activities after ICH. Risk stratification of patients according to autonomic functional activities, and development of intervention approaches based on the restoration of sympathetic-parasympathetic balance, would potentially improve clinical outcomes in ICH patients.

CONCLUSION

The review systematically summarizes the evidence of autonomic dysfunction and its association with clinical outcomes in ICH patients, proposing that targeting autonomic dysfunction could be potentially investigated to improve the clinical outcomes.

Comparisons of heart rate variability responses to head-up tilt with and without abdominal and lower-extremity compression in healthy young individuals: a randomized crossover study

Introduction: Abdominal and lower-extremity compression techniques can help reduce orthostatic heart rate increases. However, the effects of body compression on the cardiac autonomic systems, which control heart rate, remain unclear. The primary objective of this study was to compare heart rate variability, a reflection of cardiac autonomic regulation, during a head-up tilt test with and without abdominal and lower-extremity compression in healthy young individuals. The secondary objective was to conduct a subgroup analysis, considering participant sex, and compare heart rate and heart rate variability responses to head-up tilt with and without compression therapy. Methods: In a randomized crossover design, 39 healthy volunteers (20 females, aged 20.9 ± 1.2 years) underwent two head-up tilt tests with and without abdominal and lower-extremity compression. Heart rate and heart rate variability parameters were measured during the head-up tilt tests, including the Stress Index, root mean square of successive differences between adjacent R-R intervals, low- and high-frequency components, and low-to-high frequency ratio. Results: Abdominal and lower-extremity compression reduced the orthostatic increase in heart rate (p < 0.001). The tilt-induced changes in heart rate variability parameters, except for the low-frequency component, were smaller in the compression condition than in the no-compression condition (p < 0.001). These results were consistent regardless of sex. Additionally, multiple regression analysis with potentially confounding variables revealed that the compression-induced reduction in Stress Index during the head-up tilt position was a significant independent variable for the compression-induced reduction in heart rate in the head-up tilt position (coefficient = 0.411, p = 0.025). Conclusion: Comparative analyses revealed that abdominal and lower-extremity compression has a notable impact on the compensatory sympathetic activation and vagal withdrawal typically observed during orthostasis, resulting in a reduction of the increase in heart rate. Furthermore, this decrease in heart rate was primarily attributed to the attenuation of cardiac sympathetic activity associated with compression. Our findings could contribute to the appropriate application of compression therapy for preventing orthostatic tachycardia. This study is registered with UMIN000045179.

The autonomic nervous system in atrial fibrillation-pathophysiology and non-invasive assessment

The autonomic nervous system plays a crucial role in atrial fibrillation pathophysiology. Parasympathetic hyperactivity result in a shortening of the action potential duration, a reduction of the conduction wavelength, and as such facilitates reentry in the presence of triggers. Further, autonomic remodeling of atrial myocytes in AF includes progressive sympathetic hyperinnervation by increased atrial sympathetic nerve density and sympathetic atrial nerve sprouting. Knowledge on the pathophysiological process in AF, including the contribution of the autonomic nervous system, may in the near future guide personalized AF management. This review focuses on the role of the autonomic nervous system in atrial fibrillation pathophysiology and non-invasive assessment of the autonomic nervous system.

Assessment of Autonomic Nervous System Activity Using Spectral Analysis of Heart Rate Variability After Continuous Positive Airway Pressure (CPAP) Therapy in Patients With Sleep Apnea

Heart rate variability (HRV) measurements have emerged as a valuable tool for understanding the functioning of the autonomic nervous system (ANS) and assessing the health outcomes of obstructive sleep apnea (OSA) in patients. Sleep and the ANS exert a mutual influence on each other. Sleep promotes relaxation and recovery of the ANS. Conversely, ANS activity plays a role in regulating the onset and maintenance of sleep. The impact of continuous positive airway pressure (CPAP) therapy on patient recovery levels was investigated by assessing the restoration of ANS activity using HRV indicators. The study included patients with OSA who had been on CPAP for at least eight weeks. The patients were divided into two groups, namely the experimental group (CPAP-compliant) and the control group (CPAP-non-compliant). The study included a total of 38 patients, with 20 in the CPAP-compliant group and 18 in the CPAP-non-compliant group. The HRV analysis included time- and frequency-domain measures. Data was collected in various resting conditions, including lying down, standing, regular breathing, and under physiological stress induced by deep breathing and the Valsalva maneuver. After CPAP treatment, there was an increase in the average values for SDNN for deep breathing and Valsalva maneuvers. The mean changes in SDNN for CPAP-non-compliant versus CPAP-compliant groups for normal breathing increased from 32.50±5.33 to 42.40±8.03, while the values for Valsalva increased from 20.16±2.47 to 25.45±3.03. Despite the observed variations in SDNN, there was no significant change in the average change in heart rate (∆ HR), except during the Valsalva maneuver. Post-CPAP values for the Valsalva ratio were significantly decreased in deep breathing. The E:I ratio for the CPAP-compliant group during normal breathing was 1.08±.16 compared to 1.55±.09; t (36) =-11.15, p <0.001 in the CPAP-non-compliant group. During deep breathing, the ratio was 1.36±.15 versus 1.59±.24; t (36) =-3.578, p <0.001. The high frequency (HF)nu mean values for deep breathing were 34.06±5.546 compared to 35.00±6.358; t (36) = -.485, p=.630. For the Valsalva maneuver, the values were 29.94±4.721 versus 26.95±6.621; t (36) =1.589, p=.060. The HF/low frequency (LF) ratio was found to be significant only in supine, standing, and normal breathing. The utilization of CPAP therapy was found to be effective in achieving and sustaining autonomic balance during tasks like standing and engaging in regular breathing patterns. During activities that involve intense physical effort, like the Valsalva maneuver, the HRV metrics did not indicate any significant balance between sympathetic and parasympathetic activity. However, using CPAP therapy for a prolonged period can be beneficial in consistently improving the sympathovagal balance in these patients.

Prenatal fluoride exposure, offspring visual acuity and autonomic nervous system function in 6-month-old infants

BACKGROUND

Prenatal fluoride exposure can have adverse effects on children's development; however, associations with visual and cardiac autonomic nervous system functioning are unknown. We examined associations between prenatal fluoride exposure and visual acuity and heart rate variability (HRV) in 6-month-old infants.

METHODS

We used data from Canadian mother-infant pairs participating in the Maternal-Infant Research on Environmental Chemicals (MIREC) cohort. We estimated prenatal fluoride exposure using: i) fluoride concentration in drinking water (mg/L), ii) maternal urinary fluoride adjusted for specific gravity (MUFSG; mg/L) and averaged across pregnancy, and iii) maternal fluoride intake (µg/kg/day) from consumption of water, tea, and coffee, adjusted for maternal body weight (kg). We used multivariable linear regression to examine associations between each measure of fluoride exposure and Teller Acuity Card visual acuity scores (n = 435) and assessed HRV (n = 400) using two measures: root mean square of successive differences (RMSSD) and the standard deviation of N-N intervals (SDNN) measured at 6-months of age.

RESULTS

Median (IQR) values for water fluoride, MUFSG, and daily fluoride intake were 0.20 (IQR: 0.13-0.56) mg/L; 0.44 (0.28-0.70) mg/L and 4.82 (2.58-10.83) µg/kg/day, respectively. After adjustment for confounding variables, water fluoride concentration was associated with poorer infant visual acuity (B = -1.51; 95 % CI: -2.14,-0.88) and HRV as indicated by lower RMSSD (B = -1.60; 95 % CI: -2.74,-0.46) but not SDNN. Maternal fluoride intake was also associated with poorer visual acuity (B = -0.82; 95 % CI: -1.35,-0.29) and lower RMSSD (B = -1.22; 95 % CI: -2.15,-0.30). No significant associations were observed between MUFSG and visual acuity or HRV.

CONCLUSION

Fluoride in drinking water was associated with reduced visual acuity and alterations in cardiac autonomic function in infancy, adding to the growing body of evidence suggesting fluoride's developmental neurotoxicity.

The Stress Phenotyping Framework: A multidisciplinary biobehavioral approach for assessing and therapeutically targeting maladaptive stress physiology

Although dysregulated stress biology is becoming increasingly recognized as a key driver of lifelong disparities in chronic disease, we presently have no validated biomarkers of toxic stress physiology; no biological, behavioral, or cognitive treatments specifically focused on normalizing toxic stress processes; and no agreed-upon guidelines for treating stress in the clinic or evaluating the efficacy of interventions that seek to reduce toxic stress and improve human functioning. We address these critical issues by (a) systematically describing key systems and mechanisms that are dysregulated by stress; (b) summarizing indicators, biomarkers, and instruments for assessing stress response systems; and (c) highlighting therapeutic approaches that can be used to normalize stress-related biopsychosocial functioning. We also present a novel multidisciplinary Stress Phenotyping Framework that can bring stress researchers and clinicians one step closer to realizing the goal of using precision medicine-based approaches to prevent and treat stress-associated health problems.

Microstates of the cortical brain-heart axis

Electroencephalographic (EEG) microstates are brain states with quasi-stable scalp topography. Whether such states extend to the body level, that is, the peripheral autonomic nerves, remains unknown. We hypothesized that microstates extend at the brain-heart axis level as a functional state of the central autonomic network. Thus, we combined the EEG and heartbeat dynamics series to estimate the directional information transfer originating in the cortex targeting the sympathovagal and parasympathetic activity oscillations and vice versa for the afferent functional direction. Data were from two groups of participants: 36 healthy volunteers who were subjected to cognitive workload induced by mental arithmetic, and 26 participants who underwent physical stress induced by a cold pressure test. All participants were healthy at the time of the study. Based on statistical testing and goodness-of-fit evaluations, we demonstrated the existence of microstates of the functional brain-heart axis, with emphasis on the cerebral cortex, since the microstates are derived from EEG. Such nervous-system microstates are spatio-temporal quasi-stable states that exclusively refer to the efferent brain-to-heart direction. We demonstrated brain-heart microstates that could be associated with specific experimental conditions as well as brain-heart microstates that are non-specific to tasks.

Autonomic nervous system dysfunction in pediatric sport-related concussion: a systematic review

Objective

To identify, appraise and synthesize the evidence of autonomic nervous system (ANS) dysfunction following sport-related concussion in pediatric populations.

Methods

A literature search was conducted using MEDLINE (Ovid), SportDiscus (EBSCO), CINAHL (EBSCO), EMBASE (Ovid) and PsycINFO (Ovid). Studies were selected and appraised using the Joanna Briggs Institute (JBI) critical appraisal tools. Data was extracted from the included studies and qualitatively synthesized.

Results

Eleven studies were included in the synthesis. There was variability in the methods used to measure ANS function between studies, and sample populations and time to assessment following concussion varied considerably. There was also variability in the direction of change of ANS function between some studies.

Conclusion

This systematic review identifies that concussion is associated with dysregulation of ANS function in pediatric athletes. We identified some weaknesses in the extant literature which may be due to existing logistical and financial barriers to implementing valid ANS measurements in clinical and sports settings.

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.

Autonomic Nervous System Dysfunction in Peritoneal Dialysis Patients: An Underrecognized Cardiovascular Risk Factor?

BACKGROUND

In patients with end-stage kidney disease (ESKD) receiving peritoneal dialysis (PD), cardiovascular events represent the predominant cause of morbidity and mortality, with cardiac arrhythmias and sudden death being the leading causes of death in this population. Autonomic nervous system (ANS) dysfunction is listed among the non-traditional risk factors accounting for the observed high cardiovascular burden, with a plethora of complex and not yet fully understood pathophysiologic mechanisms being involved.

SUMMARY

In recent years, preliminary studies have investigated and confirmed the presence of ANS dysfunction in PD patients, while relevant results from cohort studies have linked ANS dysfunction with adverse clinical outcomes in these patients. In light of these findings, ANS dysfunction has been recently receiving wider consideration as an independent cardiovascular risk factor in PD patients. The aim of this review was to describe the mechanisms involved in the pathogenesis of ANS dysfunction in ESKD and particularly PD patients and to summarize the existing studies evaluating ANS dysfunction in PD patients.

KEY MESSAGES

ANS dysfunction in PD patients is related to multiple complex mechanisms that impair the balance between SNS/PNS, and this disruption represents a crucial intermediator of cardiovascular morbidity and mortality in this population.

Belonging Exacerbates the Relations Between Racial Climate Stress and Physiological Dysregulation

OBJECTIVE

Belonging is often considered a buffer against the physical and emotional consequences of discrimination and racial climate stress Youth Soc. 48(5):649-72, 2016. However, recent research suggests that feelings of belonging toward an institution can be detrimental when an individual feels discriminated against by the same institution to which one feels a sense of connection J Behav Med. 44(4):571-8, 2021. Therefore, the present study aimed to investigate the moderating role of institutional belonging in the relationship between racial climate stress and health, as indexed by allostatic load (AL), a multi-system indicator of physiological dysregulation.

METHODS

In a sample of Black and White college students (N = 150; White = 82; Black = 68), self-reported racial climate stress, institutional belonging, and various demographic variables were collected. An AL composite was also collected, comprised of six biological measures of the SAM system, HPA axis, cardiovascular system, and metabolic system. Multiple regression analyses were conducted to explore the relationships between these variables.

RESULTS

Results demonstrated no main effect of racial climate stress on AL but did show a significant interaction between racial climate stress and belonging, such that the positive relationship between racial climate stress and AL was significant only for those who also felt high levels of institutional belonging (β int = .05, p = .006, 95% CI = 0.01 - 0.08).

CONCLUSIONS

Feeling a sense of belonging may have negative physiological consequences for those who experience racial climate stress in a college setting.

Heart-Rate Variability Correlates to Choroidal Thickness in Central Serous Chorioretinopathy

Purpose

Patients with central serous chorioretinopathy (CSC) have previously been shown to have a lower heart rate variability (HRV), implying a lower vagal tone. Vagal tone alters mineralocorticoids, which in turn affect the thickness of the choroid. Since increased choroidal thickness is characteristic of CSC, we wanted to investigate its correlation with HRV.

Patients and Methods

In this case-control study, 21 acute CSC patients and 31 healthy controls were included. Diagnosis was confirmed by optical coherence tomography (OCT) and retinal examination. HRV was evaluated following accepted standards. Outcome measures were chosen beforehand as follows: Standard deviation of N-N intervals (SDNN), root mean square of successive differences (RMSDD), low frequency/high frequency ratio (LF/HF ratio), and standard deviation ratio from commonly used Poincare plot (SD2/SD1 ratio). Choroidal thickness was measured using OCT directly under the foveola.

Results

Patients and healthy controls did not differ in health and medical characteristics in addition to CSC disease. Choroidal thickness was greatest in patients with CSC (mean±SD: 342±80 μm) compared to controls (235±60 μm, p<0.0001). A correlation was observed between LF/HF ratio and choroidal thickness in patients with CSC (Pearson correlation 0.63, p=0.02), where the CSC group had a lower LF/HF ratio (Median 2.39 ms2, IQR: 1.2-4.34 ms2) compared to controls (Median 1.2 ms2, IQR: 0.9-2.4 ms2, p=0.06) and SD2/SD1 ratio (CSC 0.59±0.2 vs controls 0.74±0.3, p=0.06).

Conclusion

We found a correlation between the thickness of the choroid and the HRV-measured LF/HF ratio in patients with CSC and showed a borderline significant reduction in HRV measurements in patients with CSC. The data imply that vagal alterations exist in patients with CSC. Due to the low n, this should be considered as a pilot study. Further studies are warranted to elucidate mechanisms and validate findings.

Autonomic responses to aerobic and resistance exercise in patients with chronic musculoskeletal pain: A systematic review

BACKGROUND

It is unknown whether patients with chronic musculoskeletal pain (CMP) show autonomic dysregulation after exercise, and the interventional effects of exercise on the autonomic dysregulation have not been elucidated. The objectives of this study were to reveal acute autonomic responses after aerobic and resistance exercises and the interventional effects of both exercises on autonomic dysregulation in patients with CMP.

METHODS

A systematic search using nine electronic databases was performed based on three key search terms: "chronic musculoskeletal pain," "autonomic nervous system," and "exercise." Data were extracted from measurements of the autonomic nervous system and pain.

RESULTS

We found a total of 1170 articles; 17 were finally included, incorporating 12 observational and five interventional studies. Although a comparator has not been specified, healthy controls were compared to patients with CMP in observational studies. Three of five interventional studies were pre-post study with healthy controls as a comparator or no controls. The other two interventional studies were randomized controlled trial with a different treatment e.g., stretching. There were four good, 10 fair, and three poor-quality articles. The total number of participants was 617, of which 551 were female. There was high heterogeneity among the five disease conditions and nine outcome measures. Following one-time exposure to aerobic and resistance exercises, abnormal autonomic responses (sympathetic activation and parasympathetic withdrawal), which were absent in healthy controls, were observed in patients with CMP. The effects of aerobic and resistance exercise as long-term interventions were unclear since we identified both positive effects and no change in the autonomic activities in patients with CMP.

CONCLUSIONS

This study indicates dysfunctional autonomic responses following one-time exposure to exercise and inconsistent interventional effects in the autonomic activities in patients with CMP. Appropriate therapeutic dose is necessary for studying the management of autonomic regulation and pain after exercise.

COVID-19-induced gastrointestinal autonomic dysfunction: A systematic review

BACKGROUND

It is common for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection to occur in the gastrointestinal tract, which can present itself as an initial symptom. The severity of coronavirus disease 2019 (COVID-19) is often reflected in the prevalence of gastrointestinal symptoms. COVID-19 can damage the nerve supply to the digestive system, leading to gastrointestinal autonomic dysfunction. There is still much to learn about how COVID-19 affects the autonomic nervous system and the gastrointestinal tract.

AIM

To thoroughly explore the epidemiology and clinical aspects of COVID-19-induced gastrointestinal autonomic dysfunction, including its manifestations, potential mechanisms, diagnosis, differential diagnosis, impact on quality of life, prognosis, and management and prevention strategies.

METHODS

We conducted a thorough systematic search across various databases and performed an extensive literature review. Our review encompassed 113 studies published in English from January 2000 to April 18, 2023.

RESULTS

According to most of the literature, gastrointestinal autonomic dysfunction can seriously affect a patient's quality of life and ultimate prognosis. Numerous factors can influence gastrointestinal autonomic nervous functions. Studies have shown that SARS-CoV-2 has a well-documented affinity for both neural and gastrointestinal tissues, and the virus can produce various gastrointestinal symptoms by reaching neural tissues through different pathways. These symptoms include anorexia, dysgeusia, heartburn, belching, chest pain, regurgitation, vomiting, epigastric burn, diarrhea, abdominal pain, bloating, irregular bowel movements, and constipation. Diarrhea is the most prevalent symptom, followed by anorexia, nausea, vomiting, and abdominal pain. Although COVID-19 vaccination may rarely induce autonomic dysfunction and gastrointestinal symptoms, COVID-19-induced autonomic effects significantly impact the patient's condition, general health, prognosis, and quality of life. Early diagnosis and proper recognition are crucial for improving outcomes. It is important to consider the differential diagnosis, as these symptoms may be induced by diseases other than COVID-19-induced autonomic dysfunction. Treating this dysfunction can be a challenging task.

CONCLUSION

To ensure the best possible outcomes for COVID-19 patients, it is essential to take a multidisciplinary approach involving providing supportive care, treating the underlying infection, managing dysfunction, monitoring for complications, and offering nutritional support. Close monitoring of the patient's condition is crucial, and prompt intervention should be taken if necessary. Furthermore, conducting thorough research on the gastrointestinal autonomic dysfunction caused by COVID-19 is vital to manage it effectively.

COVID-19-induced gastrointestinal autonomic dysfunction: A systematic review

BACKGROUND

It is common for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection to occur in the gastrointestinal tract, which can present itself as an initial symptom. The severity of coronavirus disease 2019 (COVID-19) is often reflected in the prevalence of gastrointestinal symptoms. COVID-19 can damage the nerve supply to the digestive system, leading to gastrointestinal autonomic dysfunction. There is still much to learn about how COVID-19 affects the autonomic nervous system and the gastrointestinal tract.

AIM

To thoroughly explore the epidemiology and clinical aspects of COVID-19-induced gastrointestinal autonomic dysfunction, including its manifestations, potential mechanisms, diagnosis, differential diagnosis, impact on quality of life, prognosis, and management and prevention strategies.

METHODS

We conducted a thorough systematic search across various databases and performed an extensive literature review. Our review encompassed 113 studies published in English from January 2000 to April 18, 2023.

RESULTS

According to most of the literature, gastrointestinal autonomic dysfunction can seriously affect a patient's quality of life and ultimate prognosis. Numerous factors can influence gastrointestinal autonomic nervous functions. Studies have shown that SARS-CoV-2 has a well-documented affinity for both neural and gastrointestinal tissues, and the virus can produce various gastrointestinal symptoms by reaching neural tissues through different pathways. These symptoms include anorexia, dysgeusia, heartburn, belching, chest pain, regurgitation, vomiting, epigastric burn, diarrhea, abdominal pain, bloating, irregular bowel movements, and constipation. Diarrhea is the most prevalent symptom, followed by anorexia, nausea, vomiting, and abdominal pain. Although COVID-19 vaccination may rarely induce autonomic dysfunction and gastrointestinal symptoms, COVID-19-induced autonomic effects significantly impact the patient's condition, general health, prognosis, and quality of life. Early diagnosis and proper recognition are crucial for improving outcomes. It is important to consider the differential diagnosis, as these symptoms may be induced by diseases other than COVID-19-induced autonomic dysfunction. Treating this dysfunction can be a challenging task.

CONCLUSION

To ensure the best possible outcomes for COVID-19 patients, it is essential to take a multidisciplinary approach involving providing supportive care, treating the underlying infection, managing dysfunction, monitoring for complications, and offering nutritional support. Close monitoring of the patient's condition is crucial, and prompt intervention should be taken if necessary. Furthermore, conducting thorough research on the gastrointestinal autonomic dysfunction caused by COVID-19 is vital to manage it effectively.

McDAPS: A multi-channel physiological signals display and analysis system for clinical researchers

We introduce McDAPS, an interactive software for assessing autonomic imbalance from non-invasive multi-channel physiological recordings. McDAPS provides a graphical user interface for data visualization, beat-to-beat processing and interactive analyses. The software extracts beat-to-beat RR interval systolic blood pressure, diastolic blood pressure, the pulse amplitude of photoplethysmogram and the pulse-to-pulse interval. The analysis modules include stationary and time-varying power spectral analyses, moving-correlation analysis and univariate analyses. Analyses can also be performed in batch mode if multiple datasets have to be processed in the same way. The program exports results in standard CSV format. McDAPS runs in MATLAB, and is supported on MS Windows and MAC OS systems. The MATLAB source code is available at https://github.com/thuptimd/McDAPS.git.

Complex Brain-Heart Mapping in Mental and Physical Stress

OBJECTIVE

The central and autonomic nervous systems are deemed complex dynamic systems, wherein each system as a whole shows features that the individual system sub-components do not. They also continuously interact to maintain body homeostasis and appropriate react to endogenous and exogenous stimuli. Such interactions are comprehensively referred to functional brain-heart interplay (BHI). Nevertheless, it remains uncertain whether this interaction also exhibits complex characteristics, that is, whether the dynamics of the entire nervous system inherently demonstrate complex behavior, or if such complexity is solely a trait of the central and autonomic systems. Here, we performed complexity mapping of the BHI dynamics under mental and physical stress conditions.

METHODS AND PROCEDURES

Electroencephalographic and heart rate variability series were obtained from 56 healthy individuals performing mental arithmetic or cold-pressure tasks, and physiological series were properly combined to derive directional BHI series, whose complexity was quantified through fuzzy entropy.

RESULTS

The experimental results showed that BHI complexity is mainly modulated in the efferent functional direction from the brain to the heart, and mainly targets vagal oscillations during mental stress and sympathovagal oscillations during physical stress.

CONCLUSION

We conclude that the complexity of BHI mapping may provide insightful information on the dynamics of both central and autonomic activity, as well as on their continuous interaction.

CLINICAL IMPACT

This research enhances our comprehension of the reciprocal interactions between central and autonomic systems, potentially paving the way for more accurate diagnoses and targeted treatments of cardiovascular, neurological, and psychiatric disorders.

Effects of man-made electromagnetic fields on heart rate variability parameters of general public: a systematic review and meta-analysis of experimental studies

OBJECTIVES

The effects of man-made electromagnetic fields (EMFs) on the cardiovascular system have been investigated in many studies. In this regard, the cardiac autonomic nervous system (ANS) activity due to EMFs exposure, assessed by heart rate variability (HRV), was targeted in some studies. The studies investigating the relationship between EMFs and HRV have yielded conflicting results. We performed a systematic review and meta-analysis to assess the data's consistency and identify the association between EMFs and HRV measures.

CONTENT

Published literature from four electronic databases, including Web of Science, PubMed, Scopus, Embase, and Cochrane, were retrieved and screened. Initially, 1601 articles were retrieved. After the screening, 15 original studies were eligible to be included in the meta-analysis. The studies evaluated the association between EMFs and SDNN (standard deviation of NN intervals), SDANN (Standard deviation of the average NN intervals for each 5 min segment of a 24 h HRV recording), and PNN50 (percentage of successive RR intervals that differ by more than 50 ms).

SUMMARY

There was a decrease in SDNN (ES=-0.227 [-0.389, -0.065], p=0.006), SDANN (ES=-0.526 [-1.001, -0.05], p=0.03) and PNN50 (ES=-0.287 [-0.549, -0.024]). However, there was no significant difference in LF (ES=0.061 (-0.267, 0.39), p=0.714) and HF (ES=-0.134 (0.581, 0.312), p=0.556). In addition, a significant difference was not observed in LF/HF (ES=0.079 (-0.191, 0.348), p=0.566).

OUTLOOK

Our meta-analysis suggests that exposure to the environmental artificial EMFs could significantly correlate with SDNN, SDANN, and PNN50 indices. Therefore, lifestyle modification is essential in using the devices that emit EMs, such as cell phones, to decrease some signs and symptoms due to EMFs' effect on HRV.

The Effects of Essential Oils on the Nervous System: A Scoping Review

Essential oils are a mixture of natural aromatic volatile oils extracted from plants. The use of essential oils is ancient, and has prevailed in different cultures around the world, such as those of the Egyptians, Greeks, Persians, and Chinese. Today, essential oils are used in traditional and complimentary medicines, aromatherapy, massage therapies, cosmetics, perfumes and food industries. The screening effect of essential oils has been studied worldwide. They demonstrate a range of biological activities, such as antiparasitic, antifungal, antibacterial, antiviral, antioxidant, anti-inflammatory, anticancer, antiaging, and neuroprotective properties. In this scoping review, we provide a 10-year updated comprehensive assessment of volatile oils and their effects on the nervous system. MEDLINE, Scopus, and Google Scholar were systematically and strategically searched for original studies investigating these effects from 2012 to 2022. Approximately seventy studies were selected as included studies. Among these studies, several outcomes were reported, including antistress, antianxiety, analgesic, cognitive, and autonomic effects. Some essential oils showed developmental benefits, with the potential to induce neurite outgrowth. The neurotransmitter receptor level can also be modified by essential oil application. Physiological and pathophysiological outcome measures were reported. For physiological outcomes, arousal, cognitive performance, circadian eating behavior, emotional modulation, consumer acceptance, preferences, and willingness to buy were investigated. For pathophysiological conditions, pain, depression, anxiety, stress, sleep disorder, mental fatigue, agitated behavior, and quality of life were measured. In conclusion, essential oils showed promising effects on the nervous system, which can be further applied to their use in functional foods, drinks, and alternative therapy.

Frail OLDER ADULTS are more likely TO have autonomic dysfunction: A systematic review and META-ANALYSIs

Autonomic dysfunction and frailty are two common and complex geriatric syndromes. Their prevalence increases with age and they have similar negative health outcomes. In PubMed and Web of Science we screened studies identifying a relationship between autonomic function (AF) and frailty in adults aged ≥65 years. Twenty-two studies of which two prospective and 20 cross-sectional were included (n=8375). We performed a meta-analysis for the articles addressing orthostatic hypotension (OH). Frailty was associated with 1.6 higher odds of suffering from consensus OH (COH) {OR=1.607 95%CI [1.15-2.24]; 7 studies; n=3488}. When measured for each type of OH the largest trend was seen between initial OH (IOH) and frailty {OR=3.08; 95%CI [1.50-6.36]; 2 studies; n=497}. Fourteen studies reported other autonomic function alterations in frail older adults with 4-22% reduction in orthostatic heart rate increase, 6% reduction in systolic blood pressure recovery, 9-75% reduction in most common used heart rate variability (HRV) parameters. Frail older adults were more likely to have impaired AF. Diagnosis of frailty should promptly lead to orthostatic testing as OH implicates specific treatment modalities, which differ from frailty management. As IOH is most strongly correlated with frailty, continuous beat to beat blood pressure measurements should be performed when present at least until cut-off values for heart rate variability testing are defined.

A Pilot Study of Autonomic Function Screening Tests for Differentiating Complex Regional Pain Syndrome Type II and Traumatic Neuropathic Pain

Background and Objectives: One of the most challenging tasks in a clinical setting is to differentiate between complex regional pain syndrome (CRPS) type II and traumatic neuropathic pain (NeP). CRPS is characterized by several dysautonomic manifestations, such as edema, hyper/hypohidrosis, skin color change, and tachycardia. This study compared the outcomes of autonomic function screening tests in patients with CRPS type II and traumatic NeP for diagnostic differentiation. Materials and Methods: CRPS type II was diagnosed according to the Budapest research criteria, while NeP was diagnosed according to the updated grading system suggested by the International Association for the Study of Pain Special Interest Group on Neuropathic Pain in 2016. Twenty patients with CRPS type II and twenty-five with traumatic NeP were investigated. Results: Twelve patients with CRPS type II presented abnormal results for the quantitative sudomotor axon reflex test (QSART). Abnormal QSART results were more common in the CRPS type II group. Conclusions: Analysis of QSART combined with other ancillary tests can help in the differential diagnosis of CRPS type II and traumatic NeP if factors influencing abnormal QSART are sufficiently controlled.

Using Heart Rate Variability Methods for Health-Related Outcomes in Outdoor Contexts: A Scoping Review of Empirical Studies

Heart rate variability (HRV) is a psychophysiological variable that is often used in applied analysis techniques to indicate health status because it provides a window into the intrinsic regulation of the autonomic nervous system. However, HRV data analysis methods are varied and complex, which has led to different approaches to data collection, analysis, and interpretation of results. Our scoping review aimed to explore the diverse use of HRV methods in studies designed to assess health outcomes in outdoor free-living contexts. Four database indexes were searched, which resulted in the identification of 17,505 candidate studies. There were 34 studies and eight systematic reviews that met the inclusion criteria. Just over half of the papers referenced the 1996 task force paper that outlined the standards of measurement and physiological interpretation of HRV data, with even fewer adhering to recommended HRV recording and analysis procedures. Most authors reported an increase in parasympathetic (n = 23) and a decrease in systematic nervous system activity (n = 20). Few studies mentioned methods-related limitations and challenges, despite a wide diversity of recording devices and analysis software used. We conclude our review with five recommendations for future research using HRV methods in outdoor and health-related contexts.

Predictive value of Heart Rate Variability measurements and the Brief Resilience Scale for workability and vitality

BACKGROUND

Sustainable employability is increasingly important with current socio-economic challenges. Screening for resilience could contribute to early detection of either a risk, or a protector for sustainable employability, the latter being operationalized as workability and vitality.

OBJECTIVE

To study the predictive value of Heart Rate Variability (HRV) measurements and the Brief Resilience Scale (BRS) for worker self-reported workability and vitality after 2-4 years.

METHODS

Prospective observational cohort study with mean follow-up period of 38 months. 1,624 workers (18-65 years old) in moderate and large companies participated. Resilience was measured by HRV (one-minute paced deep breathing protocol) and the BRS at baseline. Workability Index (WAI), and the Vitality dimension of the Utrecht Work Engagement Scale-9 (UWES-9-vitality) were the outcome measures. Backward stepwise multiple regression analysis (p < 0.05) was performed to evaluate the predictive value of resilience for workability and vitality, adjusted for body mass index, age and gender.

RESULTS

N = 428 workers met inclusion criteria after follow-up. The contribution of resilience, measured with the BRS, was modest but statistically significant for the prediction of vitality (R2 = 7.3%) and workability (R2 = 9.2%). HRV did not contribute to prediction of workability or vitality. Age was the only significant covariate in the WAI model.

CONCLUSION

Self-reported resilience modestly predicted workability and vitality after 2-4 years. Self-reported resilience may provide early insight into the ability of workers to stay at work, although caution must be applied because explained variance was modest. HRV was not predictive.

Association between Polypharmacy and Cardiovascular Autonomic Function among Elderly Patients in an Urban Municipality Area of Kolkata, India: A Record-Based Cross-Sectional Study

We assessed the association between polypharmacy and cardiovascular autonomic function among community-dwelling elderly patients having chronic diseases. Three hundred and twenty-one patients from an urban municipality area of Kolkata, India were studied in August 2022. The anticholinergic burden and cardiac autonomic function (Valsalva ratio, orthostatic hypotension, change in diastolic blood pressure after an isometric exercise, and heart rate variability during expiration and inspiration) were evaluated. Binary logistic regression analysis was performed to find out the association of polypharmacy and total anticholinergic burden with cardiac autonomic neuropathy. A total of 305 patients (age, 68.9 ± 3.4; 65.9% male) were included. Of these patients, 81 (26.6%) were on polypharmacy. Out of these 81 patients, 42 patients were on ninety-eight potential inappropriate medications. The anticholinergic burden and the proportion of patients with cardiac autonomic neuropathy were significantly higher among patients who were on polypharmacy than those who were not (8.1 ± 2.3 vs. 2.3 ± 0.9; p = 0.03 and 56.8% vs. 44.6%; p = 0.01). The presence of polypharmacy and a total anticholinergic burden of > 3 was significantly associated with cardiac autonomic neuropathy (aOR, 2.66; 95% CI, 0.91−3.98 and aOR, 2.51; 95% CI, 0.99−3.52, respectively). Thus, polypharmacy was significantly associated with cardiac autonomic neuropathy among community-dwelling elderly patients.

The Utilization of Heart Rate Variability for Autonomic Nervous System Assessment in Healthy Pregnant Women: Systematic Review

BACKGROUND

The autonomic nervous system (ANS) plays a central role in pregnancy-induced adaptations, and failure in the required adaptations is associated with adverse neonatal and maternal outcomes. Mapping maternal ANS function in healthy pregnancy may help to understand ANS function.

OBJECTIVE

This study aimed to systematically review studies on the use of heart rate variability (HRV) monitoring to measure ANS function during pregnancy and determine whether specific HRV patterns representing normal ANS function have been identified during pregnancy.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline was used to guide the systematic review. The CINAHL, PubMed, SCOPUS, and Web of Science databases were searched to comprehensively identify articles without a time span limitation. Studies were included if they assessed HRV in healthy pregnant individuals at least once during pregnancy or labor, with or without a comparison group (eg, complicated pregnancy). Quality assessment of the included literature was performed using the National Heart, Lung, and Blood Institute (NHLBI) tool. A narrative synthesis approach was used for data extraction and analysis, as the articles were heterogenous in scope, approaches, methods, and variables assessed, which precluded traditional meta-analysis approaches being used.

RESULTS

After full screening, 8 studies met the inclusion criteria. In 88% (7/8) of the studies, HRV was measured using electrocardiogram and operationalized in 3 different ways: linear frequency domain (FD), linear time domain (TD), and nonlinear methods. FD was measured in all (8/8), TD in 75% (6/8), and nonlinear methods in 25% (2/8) of the studies. The assessment duration varied from 5 minutes to 24 hours. TD indexes and most of the FD indexes decreased from the first to the third trimesters in the majority (5/7, 71%) of the studies. Of the FD indexes, low frequency (LF [nu]) and the LF/high frequency (HF) ratio showed an ascending trend from early to late pregnancy, indicating an increase in sympathetic activity toward the end of the pregnancy.

CONCLUSIONS

We identified 3 HRV operationalization methods along with potentially indicative HRV patterns. However, we found no justification for the selection of measurement tools, measurement time frames, and operationalization methods, which threaten the generalizability and reliability of pattern findings. More research is needed to determine the criteria and methods for determining HRV patterns corresponding to ANS functioning in healthy pregnant persons.

Norepinephrine transporter defects lead to sympathetic hyperactivity in Familial Dysautonomia models

Familial dysautonomia (FD), a rare neurodevelopmental and neurodegenerative disorder affects the sympathetic and sensory nervous system. Although almost all patients harbor a mutation in ELP1, it remains unresolved exactly how function of sympathetic neurons (symNs) is affected; knowledge critical for understanding debilitating disease hallmarks, including cardiovascular instability or dysautonomic crises, that result from dysregulated sympathetic activity. Here, we employ the human pluripotent stem cell (hPSC) system to understand symN disease mechanisms and test candidate drugs. FD symNs are intrinsically hyperactive in vitro, in cardiomyocyte co-cultures, and in animal models. We report reduced norepinephrine transporter expression, decreased intracellular norepinephrine (NE), decreased NE re-uptake, and excessive extracellular NE in FD symNs. SymN hyperactivity is not a direct ELP1 mutation result, but may connect to NET via RAB proteins. We found that candidate drugs lowered hyperactivity independent of ELP1 modulation. Our findings may have implications for other symN disorders and may allow future drug testing and discovery.

A flexible adhesive surface electrode array capable of cervical electroneurography during a sequential autonomic stress challenge

This study introduces a flexible, adhesive-integrated electrode array that was developed to enable non-invasive monitoring of cervical nerve activity. The device uses silver-silver chloride as the electrode material of choice and combines it with an electrode array consisting of a customized biopotential data acquisition unit and integrated graphical user interface (GUI) for visualization of real-time monitoring. Preliminary testing demonstrated this electrode design can achieve a high signal to noise ratio during cervical neural recordings. To demonstrate the capability of the surface electrodes to detect changes in cervical neuronal activity, the cold-pressor test (CPT) and a timed respiratory challenge were employed as stressors to the autonomic nervous system. This sensor system recording, a new technique, was termed Cervical Electroneurography (CEN). By applying a custom spike sorting algorithm to the electrode measurements, neural activity was classified in two ways: (1) pre-to-post CPT, and (2) during a timed respiratory challenge. Unique to this work: (1) rostral to caudal channel position-specific (cephalad to caudal) firing patterns and (2) cross challenge biotype-specific change in average CEN firing, were observed with both CPT and the timed respiratory challenge. Future work is planned to develop an ambulatory CEN recording device that could provide immediate notification of autonomic nervous system activity changes that might indicate autonomic dysregulation in healthy subjects and clinical disease states.

Psychosocial stress and cancer risk: a narrative review

BACKGROUND

It is unclear which psychological factors (stressors, emotional correlates, and psychophysiological markers) induce cancer risk. This currently limits the potential for prevention strategies.

PURPOSE

The aim of this review is to bring forth evidence of stress as a determinant of cancer risk from a public health perspective, written for a broad public of practitioners and scientists.

METHODS

Based on a semisystematic literature search, the impact of different aspects/types of stress and the potential physiological and behavioral pathways are summarized, while highlighting further research, public health and clinical implications.

RESULTS

Between 2007 and 2020, 65 case-control or cohort studies have been identified. Apart from overall cancer ( N = 24), 12 cancer types have been associated with psychological stress with most for breast ( N = 21), colorectal ( N = 11) and lung/prostate/pancreas cancer ( N = 8 each). Although the evidence regarding the mechanisms is still scarce, cancer development in relation to stress might be due to interacting and combined effects of different stress(or) types, but such interaction has not really been tested yet. The path from stress towards cancer incidence consists of a biological pathway with endocrinology and immunology as well as stress-induced behavioral pathways, including smoking, alcoholism, sleep disruption, an unhealthy diet, and low physical activity together with the related phenomenon of obesity.

CONCLUSION

Not only the stress but also the stress-induced lifestyle should be targeted for cancer prevention and treatment. Future research should include a more diverse spectrum of cancer types (not only hormonal related like breast cancer) and of stress measures while also considering behavioral covariates.

Effectiveness of Semmes Weinstein 10 gm monofilament in diabetic peripheral neuropathy taking nerve conduction and autonomic function study as reference tests

Context

Diabetic peripheral neuropathy (DPN) if detected early can reduce the burden on the health system and prevent the development of diabetic foot ulcers and amputation.

Aim

To study the effectiveness of Semmes Weinstein 10 gm monofilament in detecting DPN taking nerve conduction studies (NCS) and autonomic function testing (AFT) as reference tests.

Settings and Design

Observational and comparative cross-sectional study conducted in the Physiology department AIIMS, Bhopal in collaboration with the Medicine department of the institute.

Methods and Material

A total of 72 diagnosed type-2 diabetes mellitus patients were examined using Semmes Weinstein 10 gm monofilament, DPN was confirmed using NCS (Nihon Kohden Neuropack XI machine) and autonomic neuropathy was confirmed using AFT (Ewing's battery and Power lab) with heart rate variability (HRV). Diagnostic value of Semmes Weinstein 10 gm monofilament taking NCS and AFT as reference test was calculated.

Statistical Analysis Used

Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) were calculated using the standard formula.

Results

Sensitivity, specificity, PPV, and NPV using monofilament are 69.23%, 20%, 69.23% and 20% respectively taking NCS as reference test and 70.59%, 0, 92.30%, and 0 respectively taking AFT as reference test.

Conclusions

Semmes Weinstein 10 gm monofilament is not the ideal screening test for the diagnosis of DPN. Sole clinical use of monofilament should be discouraged.

The effect of obstructive sleep apnea therapy on cardiovascular autonomic function: a systematic review and meta-analysis

STUDY OBJECTIVES

Autonomic function is impaired in obstructive sleep apnea (OSA) and may mediate the association between OSA and cardiovascular risk. We investigated the effect of OSA therapy on autonomic function through a systematic review and meta-analysis of intervention studies.

METHODS

A systematic search using three databases (Medline, Embase, and Scopus) was performed up to December 9, 2020. Studies of OSA patients ≥ 18 years with autonomic function assessed before and after treatment with positive airway pressure, oral appliance, positional therapy, weight loss, or surgical intervention were included for review. Random effects meta-analysis was carried out for five groups of autonomic function indices. Risk of bias was assessed using the Cochrane Collaboration tool.

RESULTS

Forty-three eligible studies were reviewed with 39 included in the meta-analysis. OSA treatment led to large decreases in muscle sympathetic nerve activity (Hedges' g = -1.08; 95% CI -1.50, -0.65, n = 8) and moderate decreases in catecholamines (-0.60; -0.94, -0.27, n = 3) and radio nucleotide imaging (-0.61; -0.99, -0.24, n = 2). OSA therapy had no significant effect on baroreflex function (Hedges' g = 0.15; 95% CI -0.09, 0.39, n = 6) or heart rate variability (0.02; -0.32, 0.36, n = 14). There was a significant risk of bias due to studies being primarily non-randomized trials.

CONCLUSIONS

OSA therapy selectively improves autonomic function measures. The strongest evidence for the effect of OSA therapy on autonomic function was seen in reduced sympathetic activity as assessed by microneurography, but without increased improvement in parasympathetic function. OSA therapy may reduce the risk of cardiovascular disease in OSA through reduced sympathetic activity.

Post-Acute Effect of SARS-CoV-2 Infection on the Cardiac Autonomic Function

Background

Methods

Results

Conclusion

The adapted Autonomic Profile (aAP) home-based test for the evaluation of neuro-cardiovascular autonomic dysfunction

Autonomic dysfunction is an increasingly recognised complication in chronic neurological conditions such as Parkinson’s disease, and other medical conditions, including diabetes mellitus, chronic fatigue syndrome, postural tachycardia syndrome (PoTS) with and without Ehlers-Danlos syndrome, fibromyalgia and recently Long COVID. Despite laboratory-based tests to evaluate normal and abnormal autonomic function, there are no home-based tests to record neuro-cardiovascular autonomic responses to common stimuli in daily life that are dependent on normal functioning of the autonomic nervous system. We have developed an adapted blood pressure/heart rate Autonomic Profile (aAP) that can be used by an individual independently and repeatedly in a domiciliary setting to determine the physiological and symptomatic response to standing, food, and physical or mental (cognitive, emotional) activities. The aAP aids separating autonomic failure (often irreversible) from autonomic dysfunction. This helps the individual and attending healthcare professional understand the relationship between symptoms and common triggers in daily life and informs on self-management in debilitating conditions such as the postural tachycardia syndrome (PoTS) and Long Covid.

A Review of Heart Rate and Blood Pressure Responses to Active Standing in Healthy Adults

OBJECTIVES

This review outlines the normal heart rate and blood pressure response to active standing, the physiological mechanisms governing these, and the effect of ageing on the responses.

METHODS

A literature search was conducted to identify articles investigating the normal heart rate and/or blood pressure response to standing.

RESULTS

Heart rate when standing increases and then decreases and recovers to baseline. Blood pressure responses are inverse. Skeletal muscle contraction and the baroreceptor reflex drive this. With ageing, heart rate response attenuates and the initial blood pressure response increases.

DISCUSSION

Normal heart rate and blood pressure responses are attributed to the baroreceptor reflex and skeletal muscle contraction. Decreased muscle strength and baroreceptor sensitivity are associated with ageing, suggesting a possible benefit in improving skeletal muscle strength to maintain an efficient response. Understanding these responses and their variation with ageing is clinically relevant and may be beneficial in improving rehabilitation outcomes.

Baroreflex sensitivity derived from the Valsalva manoeuvre: A physiological protective factor for anxiety induced by breathing CO2-enriched air

This study aimed to determine the capacity of baroreflex sensitivity, derived from the Valsalva manoeuvre (BRS_v), to predict state anxiety induced by a biological stressor (CO₂ inhalation). Healthy adults (n = 50) breathed 7.5 % CO₂-enriched air for 8 min, preceded and followed by breathing medical air for 5 min. State anxiety was evaluated with a visual analogue scale. Anxiety sensitivity (Anxiety Sensitivity Index-3; ASI-3) and trait anxiety (Trait form of the State-Trait Anxiety Inventory; STAI_T) served as cognitive-affective predictors. BRS_v was adopted as a physiological predictor. Multiple regression analysis revealed that BRS_v predicted lower anxiety during CO₂ exposure, and attenuated the effect of ASI-3 in increasing anxiety. No significant effects were found for STAI_T. This is the first study to identify baroreflex sensitivity as a strong protective physiological factor for anxiety beyond the effect of anxiety sensitivity.

Comparison of TWA and PEP as indices of α2- and ß-adrenergic activation

RATIONALE

Pre-ejection period (PEP) and T-wave amplitude (TWA) have been used to assess sympathetic nervous system (SNS) activity. Here we report two single-blinded, placebo-controlled intravenous (IV) drug application studies in which we pharmacologically modified SNS activity with epinephrine (study 1) as well as dexmedetomidine (alpha2-agonist) and yohimbine (alpha2-antagonist) (study 2). Restricted heart rate (HR) intervals were analyzed to avoid confounding effects of HR changes.

OBJECTIVE

Study 1 served to replicate previous findings and to validate our approach, whereas study 2 aimed to investigate how modulation of central SNS activity affects PEP and TWA.

METHODS

Forty healthy volunteers (58% females) participated in study 1 (between-subject design). Twelve healthy men participated in study 2 (within-subject design). TWA and PEP were derived from ECG and impedance cardiography, respectively.

RESULTS

Epinephrine shortened PEP and induced statistically significant biphasic TWA changes. However, although the two alpha2-drugs significantly affected PEP as expected, no effects on TWA could be detected.

CONCLUSION

PEP is better suited to reflect SNS activity changes than TWA.