Index Of Parasympathetic Activity Research Articles

Brain-body dysconnectivity: deficient autonomic regulation of cortical function in first-episode schizophrenia.

An accumulating body of evidence indicates that peripheral physiological rhythms help regulate and organize large-scale brain activity. Given that schizophrenia (SZ) is characterized by marked abnormalities in oscillatory cortical activity as well as changes in autonomic function, the present study aimed to identify mechanisms by which central and autonomic nervous system deficits may be related. We evaluated phase-amplitude coupling (PAC) as a physiological mechanism through which autonomic nervous system (ANS) and central nervous system (CNS) activity are integrated and that may be disrupted in SZ. PAC was measured between high-frequency heart rate variability (HF-HRV) as an index of parasympathetic activity and electroencephalography (EEG) oscillations in 36 individuals with first-episode SZ and 38 healthy comparison participants at rest. HRV-EEG coupling was lower in SZ in the alpha and theta bands, and HRV-EEG coupling uniquely predicted group membership, whereas HRV and EEG power alone did not. HRV-EEG coupling in the alpha band correlated with measures of sustained attention in SZ. Granger causality analyses indicated a stronger heart-to-brain effect than brain-to-heart effect, consistent across groups. Lower HRV-EEG coupling provides evidence of deficient autonomic regulation of cortical activity in SZ, suggesting that patterns of dysconnectivity observed in brain networks extend to brain-body interactions. Deficient ANS-CNS integration in SZ may foster a breakdown in the spatiotemporal organization of cortical activity, which may contribute to core cognitive impairments in SZ such as dysregulated attention. These findings encourage pursuit of therapies targeting autonomic function for the treatment of SZ.

Effects of acute hyperoxia on autonomic function and coronary tone in patients with peripheral artery disease.

Numerous studies have shown that oxidative stress plays an important role in peripheral artery disease (PAD). Prior reports suggested autonomic dysfunction in PAD. We hypothesized that responses of the autonomic nervous system and coronary tone would be impaired in patients with PAD during exposure to acute hyperoxia, an oxidative stressor. In 20 patients with PAD and 16 healthy, sex- and age-matched controls, beat-by-beat heart rate (HR, from ECG) and blood pressure (BP, with Finometer) were recorded for 10 min during room air breathing and 5 min of hyperoxia. Cardiovagal baroreflex sensitivity and HR variability (HRV) were evaluated as measures of autonomic function. Transthoracic coronary echocardiography was used to assess peak coronary blood flow velocity (CBV) in the left anterior descending coronary artery. Cardiovagal baroreflex sensitivity at rest was lower in PAD than in healthy controls. Hyperoxia raised BP solely in the patients with PAD, with no change observed in healthy controls. Hyperoxia induced an increase in cardiac parasympathetic activity assessed by the high-frequency component of HRV in healthy controls but not in PAD. Indices of parasympathetic activity were lower in PAD than in healthy controls throughout the trial as well as during hyperoxia. Hyperoxia induced coronary vasoconstriction in both groups, while the coronary perfusion time fraction was lower in PAD than in healthy controls. These results suggest that the response in parasympathetic activity to hyperoxia (i.e., oxidative stress) is blunted and the coronary perfusion time is shorter in patients with PAD.NEW & NOTEWORTHY Patients with peripheral artery disease (PAD) showed consistently lower parasympathetic activity and blunted cardiovagal baroreflex sensitivity compared with healthy individuals. Notably, hyperoxia, which normally boosts parasympathetic activity in healthy individuals, failed to induce this response in patients with PAD. These data suggest altered autonomic responses during hyperoxia in PAD.

Electrocardiographic activity depends on the relative position between intimate persons

Interpersonal space (IPS) refers to the area surrounding the body in which we engage in social interactions while maintaining our comfort. Numerous previous studies have reported the psychological and physiological changes associated with the proximity of two people engaged in face-to-face interaction. Currently, there is limited knowledge about how the relative position between two socially intimate individuals affects their psychological and physiological states. This research measured the subjective discomfort and electrocardiographic responses of participants when standing static at various relative positions. The highest discomfort, lowest heart rate, and highest heart rate variability (HRV; parasympathetic activity index) were observed when the friend stood in the face-to-face position. Interestingly, heart rate also decreased when the friend stood on the right side, although HRV did not change. We interpreted the results as suggesting that the presence of a familiar person elicits the electrocardiographic responses associated with an increase in parasympathetic activity.

Mechanical Stimulation of the Lower Extremities with a Textile-Based Pneumatic Massager Increases Parasympathetic Activity Index and Lowers Blood Glucose Levels

Mechanical Stimulation of the Lower Extremities with a Textile-Based Pneumatic Massager Increases Parasympathetic Activity Index and Lowers Blood Glucose Levels

Relaxing effects of music and odors on physiological recovery after cognitive stress and unexpected absence of multisensory benefit.

Several studies have described, often separately, the relaxing effects of music or odor on the autonomic nervous system (ANS) activity. Only a few studies compared the presentation of these stimuli and their interaction within a same experimental protocol. Here, we examined whether relaxing music (slow-paced classical pieces) and odor (lavender essential oil) either presented in isolation or in combination would facilitate physiological recovery after cognitive stress. We continuously recorded the electrocardiogram to assess the high-frequency component of heart rate variability (HF-HRV), an index of parasympathetic activity, and electrodermal activity (EDA), an index of sympathetic activity, 10min before, during and 30 min after a cognitive stress (i.e., completing timely constrained cognitively demanding tasks) in 99 participants allocated to four recovery conditions (control N=26, music N=23, odor N=24, music+odor N=26). The stressing event triggered both a significant increase in EDA and decrease in HF-HRV (compared to baseline). During the recovery period, the odor elicited a greater decrease in EDA compared to an odorless silent control, whereas no difference in HRV was observed. Conversely, during this period, music elicited a greater increase in HF-HRV compared to control whereas no difference in EDA was observed. Strikingly, in the multimodal music+odor condition, no beneficial effect was observed on ANS indexes 30 min after stress. Overall, our study confirms that both olfactory and musical stimuli have relaxing effects after stress on ANS when presented separately only, which might rely on distinct neural mechanisms and autonomic pathways.

Effets d’un programme de marche rapide chez le sujet institutionnalisé sur l’activité du système nerveux ­autonome

Introduction: The age-related decline of the autonomic nervous system (ANS) activity is a well-known risk factor for adverse cardiovascular outcomes that can be prevented through regular physical activity (PA) but PA engagement remains too low in older adults. The aim of this study was to investigate the effects of a 9-month brisk walking training on the ANS activity assessed through the measure of heart rate variability (HRV). Methods: Sixty-one older adults aged 60 and over were recruited among 14 French nursing homes to participate in a randomized control trial that consisted of a 9-month brisk walking training. They were randomized into three intervention groups: 1 exercise session per week, 3 exercise sessions per week, and a control group. HRV was measured at baseline and at the 3, 6, and 9-month visits. Results: Compared with individuals from the control group and those who exercised 1 day per week, older adults who performed 3 sessions per week exhibited a significant improvement in HRV indices of parasympathetic activity (root mean square of successive differences – RMSSD). Conclusion: Regular PA performed 3 times per week is effective in enhancing cardiac autonomic drive in nursing home older adults aged 60 and over.

코그니사이즈(Cognicise)와 매트 필라테스 복합 운동이 여성 노인의 신체조성과 정신건강 지수에 미치는 영향

In this study, elderly women were subjected to a combination of Cognicise and Pilates exercise 3 times a week for 12 weeks to determine their body composition (weight, muscle mass, body fat percentage, waist circumference, hip circumference) and mental health index (pulse wave, brain wave). It was carried out to analyze what kind of effect it has, and the following conclusions were obtained through the results.BR First, in body composition, the exercise group significantly (p.01) decreased in body weight, significantly increased (p.01) muscle mass, and significantly (p.05) decreased waist and hip circumferences. Second, in the exercise group, the HRV-index and sympathetic nerve activity index among the pulse wave items increased significantly (p.001), and the autonomic nerve health index also increased significantly (p.01). Body (autonomic nerve) age decreased significantly (p.001). The control group significantly (p.01) decreased in the parasympathetic activity index. EEG significantly (p.001) increased in the exercise group in the brain health score. The control group showed a significant (p.05) increase in body weight and body fat percentage. As described above, 12 weeks of Cognicise and Pilates combined exercise is effective for positive changes in body composition and improvement of mental health index in elderly women, and it is thought to be helpful in maintaining a healthy life.

The Relationship Between Sexual Activity and Heart Rate Variability in Menopausal Women.

Background:Menopause is an important life stage for women, which can bring along sexual and cardiac problems. Increased heart rate variability is an indicator of parasympathetic activity and is associated with mental and physical health and life expectancy. This study aimed to evaluate the effect of sexual activity (only penile–vaginal intercourse but not masturbation or non-coital sex with a partner) on heart rate variability in healthy menopausal women.Methods:We evaluated 130 menopausal patients aged 45-60 years, without chronic disease. The average weekly sexual activity numbers remembered in the last 1 year were questioned. The patients were divided into 2 groups according to the presence of sexual activity. The sexually active group was divided into subgroups as 1 per week and 2 or more per week. Menopause Rating Scale was applied for menopausal symptoms. Heart rate variability was analyzed from the 24-hour electrocardiography Holter recording.Results:Heart rate variability parameters were higher in the sexually active group than in the sexually inactive group (mean of the standard deviations of all the NN intervals for each 5 min segment of a 24-hour heart rate variability recording: P = .004; root mean square of differences between adjacent normal RR intervals, expressed in ms: P = .001; number of NN intervals exceeding 50 milliseconds: P = .011; percentage of adjacent RR intervals with a difference of duration >50 ms: P = .009; low frequency: P = .011; high frequency: P = .008, low frequency/high frequency: P = .018). When assessed by multiple linear regression analysis by adjusting for age, body mass index, and menopause duration, the variables mean of the standard deviations of all the NN intervals for each 5 min segment of a 24-hour heart rate variability recording, root mean square of differences between adjacent normal RR intervals, expressed in ms, and low frequency were independently associated with the number of sexual activities per week (B = 2.89 ± 1.02, 95% CI = 0.866-4.91, P = .005; B = 4.57 ± 1.83, 95% CI = 0.94-8.2, P = .014; and B = 1174.9 ± 592.2, 95% CI = 2.9-2346.9, P = .049, respectively).Conclusion:In healthy menopausal women, continued sexual activity with penile–vaginal intercourse is associated with better health outcomes on cardiac autonomic function through higher heart rate variability, an index of parasympathetic activity.

Resting autonomic activity in adults who stutter and its association with self-reports of social anxiety

PurposeThe purpose of this study was to investigate resting autonomic activity in adults who stutter (AWS) compared to adults who do not stutter (ANS) and the relationship this has on self-reports of social anxiety. MethodsThirteen AWS and 15 ANS completed the Social Interaction Anxiety Scale (SIAS; Mattick & Clark, 1998) and Brief Fear of Negative Evaluation (BFNE; Leary, 1983). Following this, measures of skin conductance levels (i.e. index of sympathetic activity) and respiratory sinus arrhythmia (i.e. index of parasympathetic activity) were taken during a 5-minute resting, baseline period. Independent sample t tests were used to assess differences between groups on self-reports of anxiety (SIAS, BFNE) and resting autonomic levels (SCL, RSA). Separate multiple regression analyses were performed in order to assess the relationship between self-reports of anxiety and autonomic measures. ResultsResults showed significantly higher mean SCL and lower mean RSA levels in the AWS compared to the ANS at resting, baseline. Regression analysis showed that self-reports from the SIAS had a significant effect on RSA levels for the AWS but not the ANS. No significant effects were found for BFNE on RSA. Nor was there a significant effect from SIAS or BFNE on SCL levels for either group. ConclusionFindings suggest that resting RSA levels may be a physiological marker for social anxiety levels in adults who stutter.

Does COVID‐19 influence the sympathetic regulation of blood pressure?

Does COVID‐19 influence the sympathetic regulation of blood pressure?

Non-medical prescription opioid users exhibit dysfunctional physiological stress responses to social rejection

Non-medical prescription opioid use (NMPOU) recently increased dramatically, especially in the U.S. Although chronic opioid use is commonly accompanied by deficits in social functioning and dysregulation of the hypothalamic-pituitary adrenergic (HPA) stress axis, little is known about the impact of NMPOU on psychosocial stress responses. Therefore, we measured physiological responses of the autonomic nervous system and the HPA axis to social rejection using the Cyberball paradigm. We compared 23 individuals with NMPOU, objectively confirmed by hair and urine analyses, with 29 opioid-naïve, healthy controls. As expected, heart rate variability (HRV), an index of parasympathetic activity, increased significantly during exclusion within controls, while in the NMPOU group only a trend in the same direction was found. However, increased HRV was robustly moderated by opioid craving indicating worse emotion regulation to social exclusion specifically in individuals with high opioid craving. Greater levels of the adrenocorticotropic hormone and cortisol responses to social rejection were found in the NMPOU group indicating hyperreactivity of the HPA axis to social exclusion. Self-ratings suggest that opioid users were aware of rejection, but less emotionally affected by exclusion. Furthermore, controls showed greater negative mood after the Cyberball confirming the task’s validity. Moreover, NMPOU individuals reported a smaller social network size compared to controls. Present findings suggest that chronic NMPOU is associated with dysfunctional physiological responses to psychosocial stressors such as social rejection. In sum, NMPOU was associated with poorer regulation of the parasympathetic nervous system, especially under opioid craving highlighting its potential importance in relapse prevention.

Attachment buffers the physiological impact of social exclusion.

Attachment systems facilitate coping with stress, with previous studies demonstrating attachment figures diminishing subjective, behavioral and neural responses to social pain. Yet little is known about the physiological mechanisms governing this benefit in the context of social exclusion. This study investigated the impact of attachment (vs non-attachment) priming on affective and cardiovascular responses to social exclusion induced by the computerized “Cyberball” ball-tossing game, and the moderating influence of individual differences in attachment style, rejection sensitivity and self-construal. No significant change in high frequency heart rate variability (HF-HRV)–an index of parasympathetic activity and cardiovagal balance–was observed across the time course in the attachment priming condition, whereas the non-attachment condition showed significant fluctuation in HF-HRV–increasing during Cyberball and decreasing relative to baseline during recovery. Moreover, the benefit afforded by attachment priming on was enhanced amongst participants with lower rejection sensitivity and higher collectivistic self-construal, and those with higher anxious attachment style in the non-attachment prime group showed a trend towards increased HF-HRV during the Cyberball. Results are consistent with Social Baseline Theory, which argues that social proximity–particularly from attachment figures–protects against the metabolic costs associated with strong reactions to stress, including the preservation of cardiovagal homeostasis in this instance. Social attachments may provide an important mechanism to increase adaptive responding to the distressing experience of social exclusion.

Measures of sympathetic and parasympathetic autonomic outflow from heartbeat dynamics.

Reliable and effective noninvasive measures of sympathetic and parasympathetic peripheral outflow are of crucial importance in cardiovascular physiology. Although many techniques have been proposed to take up this long-lasting challenge, none has proposed a satisfying discrimination of the dynamics of the two separate branches. Spectral analysis of heart rate variability is the most currently used technique for such assessment. Despite its widespread use, it has been demonstrated that the subdivision in the low-frequency (LF) and high-frequency (HF) bands does not fully reflect separate influences of the sympathetic and parasympathetic branches, respectively, mainly due to their simultaneous action in the LF. Two novel heartbeat-derived autonomic measures, the sympathetic activity index (SAI) and parasympathetic activity index (PAI), are proposed to separately assess the time-varying autonomic nervous system synergic functions. Their efficacy is validated in landmark autonomic maneuvers generally employed in clinical settings. The novel measures move beyond the classical frequency domain paradigm through identification of a set of coefficients associated with a proper combination of Laguerre base functions. The resulting measures were compared with the traditional LF and HF power. A total of 236 ECG recordings were analyzed for validation, including autonomic outflow changes elicited by procedures of different nature and temporal variation, such as postural changes, lower body negative pressure, and handgrip tests. The proposed SAI-PAI measures consistently outperform traditional frequency-domain indexes in tracking expected instantaneous autonomic variations, both vagal and sympathetic, and may aid clinical decision making, showing reduced intersubject variability and physiologically plausible dynamics. NEW & NOTEWORTHY While it is possible to obtain reliable estimates of parasympathetic activity from the ECG, a satisfying method to disentangle the sympathetic component from HRV has not been proposed yet. To overcome this long-lasting limitation, we propose two novel HRV-based indexes, the sympathetic and parasympathetic activity indexes.

Parasympathetic Regulation and Inhibitory Control Predict the Development of Externalizing Problems in Early Childhood.

The current report examined the longitudinal relations between cognitive self-regulation, physiological self-regulation, and externalizing problems. At age 4 (n=98; 49 girls) and 6 (n=87; 42 girls), children completed the Day-Night task, which taps the inhibitory control dimension of executive function. During the task, cardiac activity was measured and respiratory sinus arrhythmia (RSA) was derived as an index of parasympathetic activity. Mothers reported on externalizing problems. A cross-lagged path model was used to estimate longitudinal predictions while controlling for stability in all constructs over time. Earlier inhibitory control negatively predicted later externalizing problems, but not vice versa. However, RSA reactivity moderated this link; better inhibitory control predicted fewer externalizing problems only when reactivity to the Day-Night task ranged from mild RSA suppression to RSA augmentation. Externalizing problems at 6years were highest among preschoolers who augmented RSA but showed poor inhibitory control performance, suggesting that risk for psychopathology may be better delineated by viewing self-regulation from an integrated, multi-system perspective.

Maternal rearing environment impacts autonomic nervous system activity.

While it is now well known that social deprivation during early development permanently perturbs affective responding, accumulating evidence suggests that less severe restriction of the early social environment may also have deleterious effects. In the present report, we evaluate the affective responding of rhesus macaque (Macaca mulatta) infants raised by their mothers in restricted social environments or by their mothers in large social groups by indexing autonomic nervous system activity. Following a 25-hr evaluation of biobehavioral organization, electrocardiogram, and an index of respiration were recorded for 10 min. This allowed for an evaluation of both heart rate and respiratory sinus arrhythmia (RSA), an index of parasympathetic activity, during a challenging situation. Three- to four-month-old infants raised in restricted social environments had significantly higher heart rates and lower RSA as compared to infants raised in unrestricted social environments, consistent with a more potent stress response to the procedure. These results are consistent with mounting evidence that the environment in which individuals are raised has important consequences for affective processing.

Serotonin 2A receptor (5-HT2A) gene promoter variant interacts with chronic perceived stress to modulate resting parasympathetic activity in humans

Decreased resting vagal (parasympathetic) tone is implicated in the development of stress-related disorders, including anxiety and depression. Chronic stress elevates the expression of serotonin 2A receptors (5-HT2A), while activation of 5-HT2A leads to inhibition of parasympathetic synaptic transmission. The T allele of the promoter variant, rs6311 (C>T), of the 5-HT2A gene has been shown to increase the 5-HT2A expression in vitro and to be associated with anxiety and depressive disorders. We thus hypothesized that the 5-HT2A functional polymorphism may influence resting vagal activity among persons with chronically high levels of perceived stress. A total of 1138 well-defined healthy, medication-free Han Chinese were included for 5-HT2A genotyping. The Perceived Stress Scale (PSS) was used to measure the level of perceived stress during the last month and participants were divided into low and high PSS groups. Resting-state heart rate variability (HRV) was used to assess autonomic function. No significant between-genotype difference was found in any HRV variable in the low PSS group (n=610). However, in the high PSS group (n=528), high frequency power and root mean square of successive heartbeat interval differences (both HRV indices of parasympathetic activity) were significantly reduced in T/T genotype carriers compared to C/C homozygotes. Our findings are the first to show that individuals homozygous for the high-expressing 5-HT2A (T) allele exhibit diminished resting vagal tone—an index of stress vulnerability—when experiencing chronically elevated levels of perceived stress. The present results may advance our understanding of the genetic mechanism underlying individual differences in susceptibility to stress.

Relationships between transepidermal water loss, cutaneous microcirculatory function and autonomic nervous activity.

Several studies have shown that a deterioration of skin properties, an impaired cutaneous microcirculatory function and an imbalance of autonomic nervous activity are observed in smokers and in patients with diabetes mellitus or Raynaud's phenomenon. These observations suggest that skin properties are associated with cutaneous microcirculatory function and autonomic nervous activity in pathological conditions. However, there is no published evidence to support the concept that these two functions have any relationship with skin properties even in healthy subjects. To investigate the hypothesis that these properties are related, we conducted a survey of healthy adult subjects to investigate the relationships between cutaneous microcirculatory function and autonomic nervous activity and skin properties. The hydration of the stratum corneum and transepidermal water loss (TEWL) were investigated as skin properties, and the responsiveness of skin blood flow (SkBF) to local warming was examined as an index of cutaneous microcirculatory function in 19 healthy adult male subjects. Electrocardiograms were monitored for 24 h and heart rate variability was analysed considering low-frequency power (LF: 0.04-0.15 Hz), high-frequency power (HF: 0.15-0.40 Hz) and a ratio of low- to high-frequency power (LF/HF) as indices of autonomic nervous activity; HF is an index of parasympathetic activity, whereas LF/HF is an index of sympathovagal balance. The relationships between those indices were then analysed. A moderate negative correlation was found between TEWL and the relative maximum rate of increases in the responsiveness of SkBF on local warming. A moderate positive and a moderate negative correlation were observed between TEWL and LF/HF or HF, respectively. Moreover, a moderate negative and a moderate positive correlation were shown between the responsiveness of SkBF and LF/HF or HF, respectively. The hydration of the stratum corneum showed no correlations with any indices of microcirculation or autonomic nervous activity. These results indicate that skin barrier function, cutaneous microcirculatory function and autonomic nervous activity are mutually associated in healthy adults.

Association of neuropeptide Y promoter polymorphism (rs16147) with perceived stress and cardiac vagal outflow in humans.

Neuropeptide Y (NPY) is involved in resilience to stress, and higher vagal (parasympathetic) activity has been associated with greater stress resilience. Thus, we examined whether rs16147, a functional promoter polymorphism (C>T) of the NPY gene, could influence vagal tone during chronic high stress levels. NPY genotyping, chronic psychological stress level measurement (using the Perceived Stress Scale [PSS]), cardiac autonomic function assessment (using short-term heart rate variability [HRV]) were performed in 1123 healthy, drug-free Han Chinese participants who were divided into low- and high-PSS groups. In the high-PSS group (n = 522), the root mean square of successive heartbeat interval differences and high frequency power (both HRV indices of parasympathetic activity) were significantly increased in T/T homozygotes compared to C/C homozygotes. However, no significant between-genotype difference was found in any HRV variable in the low-PSS group (n = 601). Our results are the first to demonstrate that functional NPY variation alters chronic stress-related vagal control, suggesting a potential parasympathetic role for NPY gene in stress regulation.

A Triphasic Change of Cardiac Autonomic Nervous System During Electroconvulsive Therapy.

Dynamic autonomic activity changes have been repeatedly reported during electroconvulsive therapy (ECT). However, the specific timing of these changes remains unclear. To clarify whether sympathetic or parasympathetic nervous activity contributes separately to the second stage and the third stage during and after induced seizures by ECT, we examined heart rate (HR) and spectral analysis of variability (HRV) during ECT. Seventeen patients with depression participated in the study and underwent ECT. The R-R intervals (RRI) were recorded and analyzed sequentially for the HRV indices high-frequency (HF) (an index of parasympathetic activity) and low-frequency (LF)/high-frequency (an index of sympathetic activity) for 4 minutes before and after stimulus onset by the maximum entropy method. Averaged HRs were compared between 3 heart beats prestimulus and poststimulus onset. The HRV power in the range of 30 to 80 and 80 to 130 seconds after a seizure was compared between the HF and LF/HF components. There was a significant reduction of the averaged HR over 3 HRs just after stimulus onset, suggesting parasympathetic dominance in the first phase. The LF/HF power significantly increased in the 30 to 80 s range after stimulus onset, whereas the HF power significantly increased in the 80 to 130 s range after stimulus onset, reflecting sympathetic activation in the second phase and parasympathetic activation in the third phase, respectively. The evaluation of HR and HRV revealed a triphasic change from parasympathetic to sympathetic to parasympathetic cardiac autonomic activity after ECT stimulus onset in depression patients.

Cardiac Sympathetic Dominance and Systemic Inflammation in COPD

Cardiac autonomic dysfunction is an independent determinant of adverse outcomes in many diseases. The available literature on the relative changes in sympathetic and parasympathetic components in chronic obstructive pulmonary disease (COPD) is equivocal, the clinical and physiological correlates are poorly defined and association with markers of systemic inflammation has not been explored. As both autonomic dysfunction and systemic inflammation may contribute to cardiovascular morbidity in COPD, we hypothesized that these may be associated. Sixty three stable patients of COPD and 36 controls underwent spirometry, estimation of diffusion capacity, six-minute walk test and measurements of serum interleukin-6 (IL-6) and high-sensitivity C-Reactive protein. Cardiac autonomic activity was evaluated by standard five-minute heart rate variability (HRV) recordings to obtain time- and frequency-domain indices and the averaged heart rate. We observed that HRV indices of overall autonomic modulation, the standard deviation of time intervals between consecutive normal beats (SDNN) and total power, were greater in patients with higher levels of indices of both parasympathetic and sympathetic activity. The heart rate was significantly higher in patients indicating an overall sympathetic dominance and was inversely correlated with diffusion capacity. Serum IL-6 was inversely correlated with pNN50, an index of parasympathetic activity, and positively with LF/HF ratio, a measure of sympathetic: parasympathetic balance. None of the HRV indices was significantly correlated with physiological measures of severity. It was concluded that patients with COPD have increased cardiac autonomic modulation with sympathetic dominance. This is associated with decreased lung diffusion capacity and systemic inflammation.