Changes In Autonomic Nervous System Research Articles

Generalized tonic-clonic seizures are accompanied by changes of interrelations within the autonomic nervous system

PurposeA seizure is a strong central stimulus that affects multiple subsystems of the autonomic nervous system (ANS), and results in different interactions across ANS modalities. Here, we aimed to evaluate whether multimodal peripheral ANS measures demonstrate interactions before and after seizures as compared to controls to provide the basis for seizure detection and forecasting based on peripheral ANS signals. MethodsContinuous electrodermal activity (EDA), heart rate (HR), peripheral body temperature (TEMP), and respiratory rate (RR) calculated based on blood volume pulse were acquired by a wireless multi-sensor device. We selected 45 min of preictal and 60 min of postictal data and time-matched segments for controls. Data were analyzed over 15-min windows. For unimodal analysis, mean values over each time window were calculated for all modalities and analyzed by Friedman’s two-way analysis of variance. ResultsTwenty-one children with recorded generalized tonic-clonic seizures (GTCS), and 21 age- and gender-matched controls were included. Unimodal results revealed no significant effect for RR and TEMP, but EDA (p = 0.002) and HR (p < 0.001) were elevated 0–15 min after seizures. The averaged bimodal correlation across all pairs of modalities changed for 15-min windows in patients with seizures. The highest correlations were observed immediately before (0.85) and the lowest correlation immediately after seizures. Overall, average correlations for controls were higher. SignificanceMultimodal ANS changes related to GTCS occur within and across autonomic nervous system modalities. While unimodal changes were most prominent during postictal segments, bimodal correlations increased before seizures and decreased postictally. This offers a promising avenue for further research on seizure detection, and potentially risk assessment for seizure recurrence and sudden unexplained death in epilepsy.

Heart rate variability modifications in response to different types of exercise training in athletes.

Spectral analysis of heart rate variability (HRV) is a long-standing technique to indirectly assess neural cardiac regulation. This article specifically addressed how spectral analysis of HRV could help to understand neural cardiovascular adaptations to long-term exercise training; and inform us on training status in athletes. We reviewed literature searching for articles investigating resting cardiovascular adaptations to long-term exercise training through spectral analysis of HRV in athletes, from amateur to world class categories, practicing different sport disciplines, and focusing, in particular, on a series of work performed over time in our laboratory, which may highlight how different types of exercise training differently affect neural cardiac regulation. Spectral analysis of HRV has been shown its capability of detecting different adaptational changes in cardiac autonomic nervous system (ANS) regulation attending physical training in athletes of different sport disciplines. Studies showed that spectral analysis of HRV provide results that are sport-dependent and differ at individual level. ANS adaptations to exercise training are presented and discussed. Reported studies indicate that spectral analysis of HRV is an effective tool to monitor and optimize the training process and to predict athletic achievements in competitions. Cardiac ANS adaptations are strongly dependant on the type of training being performed. The individual nature of cardiac ANS adaptations should be considered to properly interpret the observed findings.

Strong Early Phase Parasympathetic Inhibition Followed by Sympathetic Withdrawal During Propofol Induction: Temporal Response Assessed by Wavelet-Based Spectral Analysis and Photoplethysmography.

Background: Induction of anesthesia with propofol is associated with a disturbance in hemodynamics, in part due to its effects on parasympathetic and sympathetic tone. The impact of propofol on autonomic function is unclear. In this study, we investigated in detail the changes in the cardiac autonomic nervous system (ANS) and peripheral sympathetic outflow that occur during the induction of anesthesia.Methods: Electrocardiography and pulse photoplethysmography (PPG) signals were recorded and analyzed from 30 s before to 120 s after propofol induction. The spectrogram was derived by continuous wavelet transform with the power of instantaneous high-frequency (HFi) and low-frequency (LFi) bands extracted at 1-s intervals. The wavelet-based parameters were then divided into the following segments: (1) baseline (30 s before administration of propofol), (2) early phase (first minute after administration of propofol), and (3) late phase (second minute after administration of propofol) and compared with the same time intervals of the Fourier-based spectrum [high-frequency (HF) and low-frequency (LF) bands]. Time-dependent effects were explored using fractional polynomials and repeated-measures analysis of variance.Results: Administration of propofol resulted in reductions in HFi and LFi and increases in the LFi/HFi ratio and PPG amplitude, which had a significant non-linear relationship. Significant between-group differences were found in the HFi, LFi, and LFi/HFi ratio and Fourier-based HF and LF after dividing the segments into baseline and early/late phases. On post hoc analysis, changes in HFi, LFi, and the LFi/HFi ratio were significant starting from the early phase. The corresponding effect size (partial eta squared) was > 0.3, achieving power over 90%; however, significant decreases in HF and LF were observed only in the late phase. The PPG amplitude was increased significantly in both the early and late phases.Conclusion: Propofol induction results in significant immediate changes in ANS activity that include temporally relative elevation of cardiac sympathovagal balance and reduced sympathetic activity.Clinical Trial Registration: The study was approved by the Institutional Review Board of Taipei Veterans General Hospital (No. 2017-07-009CC) and is registered at ClinicalTrials.gov (https://clinicaltrials.gov/ct2/show/NCT03613961).

Changes in Humans' Autonomic Nervous System under Dynamic Lighting Environment During A Short Rest.

Overloaded work and life stress often result in excessive fatigue and stresses in people, further leading to psychological burden and physiological disease. In this case, good rest is important in busy life. Good rest could result in good quality of life and work efficiency. In order to assist people in getting into deep rest to obtain a restorative state after fatigue, a dynamic lighting system with low-frequency change for assisting users in effective relaxation is proposed in this study. Heart rate variability analysis is used for discussing the change in the autonomic nervous system of the subjects under dynamic lighting environment, and a self-report questionnaire is applied to understand the subjects' psychological feeling. The research results indicate that the subjects significantly showed enhancement in the activities of parasympathetic nervous system within 25 minutes in the dynamic lighting process, in comparison with the steady lighting system. The questionnaire survey results also reveal that the subjects receive higher quality of rest, after the dynamic and low-illuminance lighting stimuli, with good feeling.

Is heart rate variability a risk factor for premature ejaculation?

The purpose of this study is to assess the parameters of heart rate variability, which is an indicator of the change in autonomic nervous system (ANS) activity, in individuals with premature ejaculation (PE). This study was performed by comparing 40 patients with PE (mean age, 31.2±4.1years) and 40 healthy individuals (mean age, 30.4±4.8years) without PE from May 2018 to December 2019. HRV parameters were compared between men with PE and healthy controls in 24-hour heart rhythm Holter examination. In the time domain analysis, which is a subgroup of HRV, square root of differences between consecutive normal NN intervals (RMSSD), which is an indicator of parasympathetic activity, was lower in patients with PE compared with controls (P=.025). Moreover, within the frequency domain analysis, high frequency (HF), another indicator of parasympathetic activity, was lower in patients compared with controls (P=.032). Finally, the LF/HF ratio, reflecting sympathetic/parasympathetic activity ratio, was significantly higher in patients compared with controls (P=.008). Furthermore, the multivariate logistic regression analysis showed that LF/HF ratio is independently associated with PE (P=.005). The ROC curve analysis showed that the optimal cut-off value of LF/HF above 2.7 predicted PE at a sensitivity of 77.5% and specificity of 82.5% (positive predictive value: 81.5% and negative predictive value: 78.5%). Different HRV parameters were exhibited in the comparison of patients with PE and normal controls. It suggests that the change in HRV parameters will be an indicator of imbalance in ANS and this imbalance may cause PE. Therefore, HRV analysis can be a diagnostic tool to assess altered ANS activity in patients with PE and may be considered as a rapid screening tool.

Cardiac autonomic function in Chagas disease: a narrative review

Chagas disease (CD) is a severe health problem in countries of Latin America, including Brazil, and is characterised as an acute and chronic infection. CD can affect several organs and cellular tissues, in particular the heart, which can lead to sudden death. This work aimed to review the literature regarding cardiac autonomic function assessed by Heart Rate Variability (HRV) in CD in adult individuals. The search was carried out using the electronic databases PubMed, SciELO, and Web of Science between January 2013 and October 2020. A total of 19 articles were found, of which 14 were included in this review. HRV was demonstrated at baseline conditions, physical exercise, and cardiac rehabilitation. Quantifying CD progression assessed by HRV is an effective method to detect changes in the cardiac autonomic nervous system, even in asymptomatic individuals. Physical exercise can improve autonomic function in CD. Further clinical studies are needed to assess the anatomical-functional, metabolic, and immunological parameters associated with CD evaluated by HRV.

Optimizing Autonomic Function Analysis via Heart Rate Variability Associated With Motor Activity of the Human Colon.

The parameters of heart rate variability (HRV) can non-invasively assess some autonomic activities, and HRV is influenced by many bodily actions. Although parasympathetic activity is the primary driver of colonic propulsive activity, and sympathetic activity a major inhibitor of colonic motility, they are rarely measured and almost play no role in diagnosis of colon motor dysfunction or in standard treatments. Here we set out to optimize HRV analysis of autonomic nervous system changes related to human colon motility. The electrocardiogram and impedance were recorded in synchrony with colonic motor patterns by high-resolution manometry. Respiratory sinus arrhythmia (RSA), root mean square of successive differences of beat-to-beat intervals (RMSSD), the Baevsky Index or Sympathetic Index (SI), and the ratios of SI/RSA and SI/RMSSD were shown to indicate a marked increase in parasympathetic and withdrawal of sympathetic activity during the high-amplitude propagating pressure waves (HAPWs). Strong associations were seen with HAPWs evoked by a meal and rectal bisacodyl indicating a marked increase in parasympathetic and withdrawal of sympathetic activity during the gastrocolic reflex and the defecation reflex. When HAPWs occurred in quick succession, parasympathetic activation (RSA and RMSSD) occurred in a rhythmic fashion. Hence, during propulsive motor patterns, an overall shift in autonomic activity toward increased parasympathetic control was shown to be reflected in HRV. HRV assessment may therefore be valuable in the assessment of autonomic dysfunction related to colonic dysmotility.

Early Left Ventricular Diastolic Dysfunction, Reduced Baroreflex Sensitivity, and Cardiac Autonomic Imbalance in Anabolic-Androgenic Steroid Users.

The effects of androgen anabolic steroids (AAS) use on athletes’ cardiac autonomic activity in terms of baroreflex sensitivity (BRS), and heart rate variability (HRV) have not yet been adequately studied. Furthermore, there is no information to describe the possible relationship between the structural and functional cardiac remodeling and the cardiac autonomic nervous system changes caused by AAS abuse. Thus, we aimed to study the effects of long-term AAS abuse on cardiac autonomic efficacy and cardiac adaptations in strength-trained athletes. In total, 80 strength-trained athletes (weightlifters and bodybuilders) participated in the study. Notably, 40 of them using AAS according to their state formed group A, 40 nonuser strength-trained athletes comprised group B, and 40 healthy nonathletes (group C) were used as controls. All subjects underwent a head-up tilt test using the 30 min protocol to evaluate the baroreflex sensitivity and short HRV modulation. Furthermore, all athletes undertook standard echocardiography, a cardiac tissue Doppler imaging (TDI) study, and a maximal spiroergometric test on a treadmill to estimate their maximum oxygen consumption (VO2max). The tilt test results showed that group A presented a significantly lower BRS and baroreflex effectiveness index than group B by 13.8% and 10.7%, respectively (p < 0.05). Regarding short-term HRV analysis, a significant increase was observed in sympathetic activity in AAS users. Moreover, athletes of group A showed increased left ventricular (LV) mass index (LVMI) by 8.9% (p < 0.05), compared to group B. However, no difference was found in LV ejection fraction between the groups. TDI measurements indicated that AAS users had decreased septal and lateral peak E’ by 38.0% (p < 0.05) and 32.1% (p < 0.05), respectively, and increased E/E’ by 32.0% (p < 0.05), compared to group B. This LV diastolic function alteration was correlated with the year of AAS abuse. A significant correlation was established between BRS depression and LV diastolic impairment in AAS users. Cardiopulmonary test results showed that AAS users had significantly higher time to exhaustion by 11.0 % (p < 0.05) and VO2max by 15.1% (p < 0.05), compared to controls. A significant correlation was found between VO2max and LVMI in AAS users. The results of the present study indicated that long-term AAS use in strength-trained athletes led to altered cardiovascular autonomic modulations, which were associated with indices of early LV diastolic dysfunction.

Dysfunction of the stress response in individuals with persistent post-concussion symptoms: a scoping review protocol

Background 10-15% of individuals who sustain a concussion develop persistent post-concussion symptoms (PPCS). Presently, there is no consensus regarding the pathophysiology of PPCS. Preliminary evidence suggests that individuals with PPCS have either a dysfunctional autonomic nervous system (ANS) or hypothalamic-pituitary-adrenal axis (HPA-axis). The ANS and HPA-axis collectively make up the two arms of the peripheral stress response. In the presence of a stressor, the two arms work interchangeably to return the body back to homeostasis. With concussion as the stressor, it is plausible that the development and maintenance of PPCS are due to a dysfunctional stress response. Only one study has explored the relationship between PPCS and the two arms of the stress response (ANS and HPA-axis) in combination, which presents a clear gap in the literature. Objective The proposed protocol aims to determine the extent of evidence for dysfunction of the stress response in individuals with PPCS. This review will individually map the literature surrounding quantifiable changes in the (1) ANS and (2) HPA-axis in individuals with PPCS. The review will also highlight any (3) knowledge gaps in this emerging field of research. Methods A scoping review study design has been chosen to facilitate a thorough literature search on this broad exploratory topic. The scoping review proposed will follow the recommended methodological guidelines. Conclusion Understanding the potential role of a dysfunctional stress response in those with PPCS will create more effective treatment pathways and reduce the chronicity of this condition.

Relaxation or Regulation: The Acute Effect of Mind-Body Exercise on Heart Rate Variability and Subjective State in Experienced Qi Gong Practitioners.

Mind-body exercises such as Yoga or Qi Gong have demonstrated a wide range of health benefits and hold great promise for employment in clinical practice. However, the psychophysiological mechanism underlying these effects remains unclear. Theoretical frameworks highlight regulation as a characteristic and specific mechanism of mind-body exercise for which empirical evidence is scarce. To investigate the exact nature of this mechanism, we tracked acute changes in autonomic nervous system (ANS) activity and subjective state over a common form of mind-body exercise (Qi Gong). Heart rate variability (HRV) and subjective state were assessed in 42 Qi Gong practitioners from China and Germany during a standard moving Qi Gong exercise (Baduanjin). Relaxation in supine position prior and after the exercise served as a control condition to Qi Gong and to assess changes before and after the exercise. Following Qi Gong, all practitioners reported significantly increased subjective calmness and perceived body activation, attentional focus, and subjective vitality. On the physiological level, a significant decrease of parasympathetic modulation and increase in heart rate indicated a pattern of moderate general physiological activation during Qi Gong. A significant increase in overall RR-interval modulation and cardiac coherence during Qi Gong were indicative of a mechanism of active regulation. Examination of the RR-interval trajectories revealed a rhythmic pattern of ANS activation and deactivation in sync with activating and relaxing segments of the exercise. Significant changes in subjective state, not on the physiological level, before and after the exercise were observed. Significant associations between Qi-Gong-specific beliefs, age, cultural background, and experiential and physiological measures demonstrated the complexity of mind-body exercises as multicomponent interventions. Overall, this study highlights moderate general physiological activation, exercise-dependent rhythmic ANS modulation, and induction of a characteristic state of eutonic calmness as potential psychophysiological mechanisms underlying the health benefits of mind-body exercise.

Association Between Postoperative Long-Term Heart Rate Variability and Postoperative Delirium in Elderly Patients Undergoing Orthopedic Surgery: A Prospective Cohort Study.

BackgroundPostoperative delirium (POD) is a common complication after orthopedic surgery in elderly patients. The elderly may experience drastic changes in autonomic nervous system (ANS) activity and circadian rhythm disorders after surgery. Therefore, we intend to explore the relationship between postoperative long-term heart rate (HR) variability (HRV), as a measure of ANS activity and circadian rhythm, and occurrence of POD in elderly patients.MethodsThe study population of this cohort was elderly patients over 60 years of age who scheduled for orthopedic surgery under spinal anesthesia. Patients were screened for inclusion and exclusion criteria before surgery. Then, participants were invited to wear a Holter monitor on the first postoperative day to collect 24-h electrocardiographic (ECG) data. Parameters in the time domain [the standard deviation of the normal-to-normal (NN) intervals (SDNN), mean of the standard deviations of all the NN intervals for each 5-min segment of a 24-h HRV recording (SDNNI), and the root mean square of successive differences of the NN intervals (RMSSD)] and frequency domain [heart rate (HR), high frequency (HF), low frequency (LF), very low frequency (VLF), ultra low frequency (ULF), and total power (TP)] were calculated. Assessment of delirium was performed daily up to the seventh postoperative day using the Chinese version of the 3-Min Diagnostic Interview for CAM-defined Delirium (3D-CAM). The relationship between HRV and POD, as well as the association between HRV and duration of POD, was assessed.ResultsOf the 294 cases that finally completed the follow-up, 60 cases developed POD. Among the HRV parameters, SDNNI, VLF, and ULF were related to the occurrence of POD. After adjustment for potential confounders, the correlation between HRV indices and POD disappeared. Through stratified analysis, two significant negative correlations emerged: ULF in young-old participants and SDNNI, VLF, and ULF in male patients.ConclusionThe lower HRV parameters may be related to the occurrence of POD, and this correlation is more significant in young-old and male patients. ANS disorders and rhythm abnormalities reflected by HRV changes may represent a possible mechanism that promotes POD.

A functional selective effect of oxytocin secreted under restraint stress in rats

Restraint stress (RS) is an unavoidable stress model that triggers activation of the autonomic nervous system, endocrine activity, and behavioral changes in rodents. Furthermore, RS induces secretion of oxytocin into the bloodstream, indicating a possible physiological role in the stress response in this model. The presence of oxytocin receptors in vessels and heart favors this possible idea. However, the role of oxytocin secreted in RS and effects on the cardiovascular system are still unclear. The aim of this study was to analyze the influence of oxytocin on cardiovascular effects during RS sessions. Rats were subjected to pharmacological (blockade of either oxytocin, vasopressin, or muscarinic receptors) or surgical (hypophysectomy or sinoaortic denervation) approaches to study the functional role of oxytocin and its receptor during RS. Plasma levels of oxytocin and vasopressin were measured after RS. RS increased arterial pressure, heart rate, and plasma oxytocin content, but not vasopressin. Treatment with atosiban (a Gi biased agonist) inhibited restraint-evoked tachycardia without affecting blood pressure. However, this effect was no longer observed after sinoaortic denervation, homatropine (M2 muscarinic antagonist) treatment or hypophysectomy, indicating that parasympathetic activation mediated by oxytocin secreted to the periphery is responsible for blocking the increase in tachycardic responses observed in the atosiban-treated group. Corroborating this, L-368,899 (oxytocin antagonist) treatment showed an opposite effect to atosiban, increasing tachycardic responses to restraint. Thus, this provides evidence that oxytocin secreted to the periphery attenuates tachycardic responses evoked by restraint via increased parasympathetic activity, promoting cardioprotection by reducing the stress-evoked heart rate increase.

Use of Mobile Technology Paired with Heart Rate Monitor to Remotely Quantify Behavioral Health Markers among Military Reservists and First Responders.

Heart rate variability (HRV) is a biological marker that reflects an individual's autonomic nervous system regulation. Psychological resilience is an individual's ability to recover from an adverse event and return to physiological homeostasis and mental well-being, indicated by higher resting HRV. The Biofeedback Assisted Resilience Training (BART) study evaluates a resilience-building intervention, with or without HRV biofeedback. This article evaluates the feasibility of remote psychophysiological research by validating the HRV data collected. The BART platform consists of a mobile health application (BART app) paired to a wearable heart rate monitor. The BART app is installed on the participant's personal phone/tablet to track and collect self-report psychological and physiological data. The platform collects raw heart rate data and processes HRV to server as online biofeedback. The raw data is processed offline to derive HRV for statistical analysis. The following HRV parameters are validated: inter-beat interval, respiratory sinus arrhythmia, low-frequency HRV, biofeedback HRV, and heart period. Bland-Altman and scatter plots are used to compare and contrast online and offline HRV measures. Repeated-measures ANOVA are used to compared means across tasks during the stress (rest, stress, and recovery) and training (rest and paced breathing) sessions in order to validate autonomic nervous system changes to physiological challenges. The analyses included 245 participants. Bland-Altman plots showed excellent agreement and minimal bias between online and offline unedited inter-beat interval data during the stress session. RMANOVA during the training session indicated a significant strong effect on biofeedback HRV, F(11,390) = 967.96, P < .01. During the stress session, RMANOVA showed significant strong effect on respiratory sinus arrhythmia and low-frequency HRV, and a significant but weak effect on heart period. The BART digital health platform supports remote behavioral and physiological data collection, intervention delivery, and online HRV biofeedback.

Evaluation of the Autonomic Nervous System Changes and Temporal-Spatial Gait Analysis in Patients with Ischemic Stroke Subjected to Neurorehabilitation Conventional Methods and Using Special. Literature Revie

Introduction: The persistent high rate of disability in people after stroke in Poland and globally requires continuous analysis of the effectiveness of rehabilitation. This review of the global literature analyzes the effectiveness of two therapeutic concepts in relation to changes in the autonomic nervous system and gait quality. Material and Methods: We searched PubMed for available literature using keywords. The search included literature available in English between January 2000 and June 2017. Results: Most studies described in this literature review did not show any significant advantage in terms of effectiveness of neurorehabilitation methods over conventional ones. Conclusions: The effectiveness of rehabilitation focuses mainly on modulating brain plasticity associated with neurologic deficits in the central nervous system, ignoring the autonomic nervous system.

Autonomic dysregulation and sleep homeostasis in insomnia

Insomnia is common in older adults, and is associated with poor health, including cognitive impairment and cardio-metabolic disease. Although the mechanisms linking insomnia with these comorbidities remain unclear, age-related changes in sleep and autonomic nervous system (ANS) regulation might represent a shared mechanistic pathway. In this study, we assessed the relationship between ANS activity with indices of objective and subjective sleep quality in older adults with insomnia. Forty-three adults with chronic insomnia and 16 age-matched healthy sleeper controls were studied. Subjective sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI), objective sleep quality by electroencephalogram spectral components derived from polysomnography, and ANS activity by measuring 24-h plasma cortisol and norepinephrine (NE). Sleep cycle analysis displayed lower slow oscillatory (SO: 0.5-1.25 Hz) activity in the first cycle in insomnia compared to controls. In insomnia, 24-h cortisol levels were higher and 24-h NE levels were lower than controls. In controls, but not in insomnia, there was a significant interaction between NE level during wake and SO activity levels across the sleep cycles, such that in controls but not in insomnia, NE level during wake was positively associated with the amount of SO activity in the first cycle. In insomnia, lower 24-h NE level and SO activity in the first sleep cycle were associated with poorer subjective sleep quality. Dysregulation of autonomic activity may be an underlying mechanism that links objective and subjective measures of sleep quality in older adults with insomnia, and potentially contribute to adverse health outcomes.

The Effect of Manual Lymph Drainage on the Changes of Autonomic Nervous System and Pain in Stressed Hospital Office Employees

The Effect of Manual Lymph Drainage on the Changes of Autonomic Nervous System and Pain in Stressed Hospital Office Employees

Autonomic Nervous System Changes in Individuals with Anxiety and Depression Across the Lifespan: A Systematic Review

The primary aim of this systematic review is to determine the relationship between anxiety and/or depression and heart rate variability across the age spectrum.

Classifying sleep–wake stages through recurrent neural networks using pulse oximetry signals

The regulation of the autonomic nervous system changes with the sleep stages causing variations in the physiological variables. We exploit these changes with the aim of classifying the sleep stages in awake or asleep using pulse oximeter signals. We applied a recurrent neural network to heart rate and peripheral oxygen saturation signals to classify the sleep stage every 30 seconds. The network architecture consists of two stacked layers of bidirectional gated recurrent units (GRUs) and a softmax layer to classify the output. In this paper, we used 5000 patients from the Sleep Heart Health Study dataset. 2500 patients were used to train the network, and two subsets of 1250 were used to validate and test the trained models. In the test stage, the best result obtained was 90.13% accuracy, 94.13% sensitivity, 80.26% specificity, 92.05% precision, and 84.68% negative predictive value. Further, the Cohen’s Kappa coefficient was 0.74 and the average absolute error percentage to the actual sleep time was 8.9%. The performance of the proposed network is comparable with the state-of-the-art algorithms when they use much more informative signals (except those with EEG).

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

Changes in autonomic nervous system (ANS) function have been observed in a variety of psychological disorders, including posttraumatic stress disorder (PTSD). Analysis of heart rate variability (HRV) provides insight into the functioning of the ANS. Previous research on PTSD found lower HRV in PTSD patients compared to controls, indicating altered sympathetic and parasympathetic activity, but findings are inconsistent. The purpose of this meta-analysis was to examine differences in HRV indices between individuals with PTSD and healthy controls at baseline and during stress. The included primary studies present an aggregate of studies analyzing different HRV indices. Examined HRV indices were standard deviation of the normalized NN-intervals (SDNN), root mean square of successive differences (RMSSD), low-frequency (LF) and high-frequency (HF) spectral components, LF/HF ratio, and heart rate (HR). Moderating effects of study design, HRV and PTSD assessment, and sample characteristics were examined via subgroup-analyses and meta-regressions. Random-effects meta-analyses for HRV parameters at rest revealed significant group differences for RMSSD and HF-HRV, suggesting lower parasympathetic activity in PTSD. The aggregated effect size for SDNN was medium, suggesting diminished total variability in PTSD. A small effect was found for LF-HRV. A higher LF/HF ratio was found in the PTSD sample as compared to controls. Individuals with PTSD showed significantly higher HR. During stress, individuals with PTSD showed higher HR and lower HF-HRV, both indicated by small effect sizes. Findings suggest that PTSD is associated with ANS dysfunction.

Distribution, Stability, and Continuity of Autonomic Nervous System Responsivity at 18- and 36-Months of Age.

Cardiac autonomic nervous system (ANS) measures, respiratory sinus arrhythmia (RSA) and preejection period (PEP), are valid and reliable indicators of children's sensitivity to their environment; however, there are few studies of ANS measures in children less than three years of age. This study's aim was to summarize the distributions, stability, and continuity of RSA and PEP measures during resting, challenge, and reactivity for children at 18- and 36-months. This was a cohort study of racially- and ethnically-diverse, low-income children who completed a developmentally challenging protocol while we simultaneously assessed their RSA and PEP at 18-months (N = 134) and 36-months (N = 102). The ANS resting, challenge, and reactivity measures at 18- and 36-months of age were normally distributed. The RSA resting (r = 0.29), RSA challenge (r = 0.44), PEP resting (r = 0.55) and PEP challenge (r = 0.58) measures were moderately stable but RSA (r = 0.01) and PEP reactivity (r = 0.02) were not stable from 18- to 36-months of age. There was no continuity in the ANS measures from 18- to 36-months of age with statistically significant changes in sample means for all of the ANS measures. These developmental changes in ANS are shown at the sample level but there are individual differences in ANS responses from 18- to 36-months that may be affected by adversity or protective factors experienced early in life.