Autonomic cardiac control. II. Noninvasive indices and basal response as revealed by autonomic blockades

Heart rate variability and psychological health: The key role of trait emotional awareness

Studies have shown that Trait Emotional Awareness (TEA) - the ability to recognize one's emotions - and Heart Rate Variability (HRV) are both negatively associated with psychological disorders. Although these studies imply that TEA is related to HRV and may explain the association between HRV and psychological disorders, there is limited research investigating this implication. Such investigation is essential to illuminate the psychophysiological processes linked to psychological disorders. The present study aims to investigate a) the association between TEA and HRV, b) the association between HRV and psychological disorders, and c) whether TEA explains the association between HRV and psychological disorders. A sample of 41 German students completed self-report questionnaires as indicators of psychological disorders, including the Hospital Anxiety and Depression Scale (HADS; Snaith & Zigmond, 1983) for anxiousness and depressiveness, as well as the somatization scale of the Hopkins Symptom Checklist (HSCL; Derogatis et al., 1976) for physical complaints. HRV was measured at baseline (resting HRV) and during exposure to a fear-provoking movie clip (reactive HRV). As hypothesized, a) TEA showed a positive association with reactive HRV, b) HRV showed negative associations with anxiousness and physical complaints, and c) TEA explained the relationships between reactive HRV and anxiousness, as well as physical complaints. Contrary to our hypothesis, we did not find any association between HRV and depressiveness. We discussed the contribution of TEA to psychophysiological health, limited generalizability of the current study, and direct future research to explore the underlying mechanisms linking TEA to health.

Direct and indirect effects of adiposity on markers of autonomic nervous system activity in older adults

Several cardiovascular disease (CVD) risk factors (e.g., hypertension, poor glycemic control) can affect and be affected by autonomic nervous system (ANS) activity. Since excess adiposity can influence CVD development through its effect on hypertension and diabetes mellitus, it is important to determine how adiposity and altered ANS activity are related. The present study employed structural equation modeling to investigate the relation between adiposity and ANS activity both directly and indirectly through biological variables typically associated with glycemic impairment and cardiac stress in older adults. Utilizing the Atherosclerosis Risk in Communities (ARIC) dataset, 1,145 non-smoking adults (74±4.8 yrs, 62.8% female) free from known CVD, hypertension, and diabetes and not currently taking beta-blockers were evaluated for fasting blood glucose (FBG), insulin, and HbA1c concentrations, waist circumference (WC), blood pressure (BP), and markers of ANS activity. WC was recorded just above the iliac crest and was used to reflect central adiposity. Resting 2-minute electrocardiograph recordings, pulse wave velocity, and ankle-brachial index data were used to assess the root mean square of successive differences in RR intervals (RMSSD) and the pre-ejection period (PEP), markers of parasympathetic and sympathetic activity, respectively. FBG, insulin, and HbA1c inferred a latent variable termed glycemic impairment (GI), whereas heart rate and diastolic BP inferred a latent variable termed cardiac stress (CS). The structural equation model fit was acceptable [root mean square error of approximation = 0.050 (90% CI = .036, .066), comparative fit index = .970, Tucker Lewis Index = 0.929], with adiposity having both significant direct (β = 0.208, p = 0.018) and indirect (β = -.217, p = .041) effects on PEP through GI. Adiposity displayed no significant direct effect on RMSSD. CS displayed a significant pathway (β = -0.524, p = 0.035) on RMSSD, but the indirect effect of WC on RMSSD through CS did not reach statistical significance (β = -0.094, p = 0.137). These results suggest that adiposity's relation to ANS activity is multifaceted, as increased central adiposity had opposing direct and indirect effects on markers of sympathetic activity in this population of older adults.

Respiratory sinus arrhythmia (RSA), vagal tone and biobehavioral integration: Beyond parasympathetic function

Linchpin to the entire area of psychophysiological research and discussion of the vagus is the respiratory and cardiovascular phenomenon known as respiratory sinus arrhythmia (RSA; often synonymous with high-frequency heart-rate variability when it is specifically linked to respiratory frequency), i.e. rhythmic fluctuations in heart rate synchronized to inspiration and expiration. This article aims 1) to clarify concepts, terms and measures commonly employed during the last half century in the scientific literature, which relate vagal function to psychological processes and general aspects of health; and 2) to expand upon an earlier theoretical model, emphasizing the importance of RSA well beyond the current focus upon parasympathetic mechanisms. A close examination of RSA and its relations to the vagus may 1) dispel certain commonly held beliefs about associations between psychological functioning, RSA and the parasympathetic nervous system (for which the vagus nerve plays a major role), and 2) offer fresh perspectives about the likely functions and adaptive significance of RSA, as well as RSA's relationship to vagal control. RSA is neither an invariably reliable index of cardiac vagal tone nor of central vagal outflow to the heart. The model here presented posits that RSA represents an evolutionarily entrenched, cardiovascular and respiratory phenomenon that significantly contributes to meeting continuously changing metabolic, energy and behavioral demands.

The Effect of Short-term Inhalation of Fir Essential Oil on Autonomic Nervous Activity in Middle-aged Women

This study aimed to investigate the effect of short-term inhalation of fir essential oil on autonomic nervous activity in middle-aged women. Twenty-six women (mean age, 51.0 ± 2.9 years) participated in this study. The participants sat on a chair, closed their eyes, and inhaled fir essential oil and room air (control) for 3 min. A crossover trial was performed to eliminate the effect of the order of olfactory stimulation. Approximately half of the participants were administered stimuli in the following order: exposure to fir essential oil, then control. The remaining participants were administered control, followed by fir essential oil. Heart rate variability, heart rate, blood pressure, and pulse rate were used as indicators of the autonomic nervous system activity. The Semantic Differential method and Profile of Mood States were used as psychological indicators. The High Frequency (HF) value, an indicator of parasympathetic nerve activity reflecting a relaxed state, was significantly higher during stimulation with fir essential oil than during the control condition. The Low Frequency (LF)/(LF+HF) value, an indicator of sympathetic nerve activity reflecting awake state, was marginally lower during stimulation with fir essential oil than during the control condition. No significant differences were found in heart rate, blood pressure, and pulse rate. After inhaling fir essential oil, "comfortable," "relaxed," and "natural" feelings improved, negative moods decreased, and positive moods increased. In conclusion, inhalation of fir essential oil can help menopausal women in their physiological and psychological relaxation.

Perfluoroalkyl substances (PFAS) and lead (Pb) as "cardiovascular disruptors" in 9-11-year-old children living in Syracuse, New York, United States

OBJECTIVE

Per- and polyfluoro-alkyl substances (PFAS) and lead (Pb) are ubiquitous environmental toxicants with apparent impact on cardiovascular disease (CVD) risk. As one possible mechanism for this increased risk, we have previously demonstrated an association between Pb exposure and heightened cardiovascular reactivity to acute psychological stress, a CVD risk factor. The present study expands this approach and considers both PFAS and Pb exposures (and the possible interaction).

METHODS

We assessed 14 serum PFAS and whole blood Pb concentrations in a sample of 9-11 year-old children (N = 291; 43.2% White, 56.8% Black; 53.5% female). We measured cardiovascular functioning at rest and during psychological stress as well as multiple indicators of subclinical CVD including resting blood pressure (BP), carotid-femoral pulse wave velocity (cfPWV), carotid intima-media thickness (cIMT), and left ventricular mass (LVM). Data analysis included general linear modeling as well as a non-parametric approach to study metal mixtures, specifically Bayesian Kernel Machine Regression (BKMR).

RESULTS

Significant interactions between different PFAS and with Pb suggest the importance of considering toxicant mixtures when assessing potential disruption of the cardiovascular system. The pattern of findings suggests that greater "vascular reactivity" (elevated BP and vascular resistance during acute psychological stress) was associated with higher concentrations of perfluorononanoic acid (PFNA), perfluorohexane sulfonate (PFHxS), and Pb, but only when perfluorooctanoic acid (PFOA) was concurrently elevated. With respect to subclinical outcomes, increasing perfluorodecanoic acid (PFDA) was associated with greater cIMT (β = 0.21, p = 0.010).

CONCLUSION

To our knowledge this is the first study to consider how PFAS exposures might affect cardiovascular functioning and subclinical disease. Although a complex pattern of associations emerged, it does appear that PFAS and Pb can be classified as "cardiovascular disruptors" in children. Further research is needed to replicate these novel findings and determine whether these disruptions produce future cardiovascular disease.

Heart Rate Variability Covaries with Amygdala Functional Connectivity During Voluntary Emotion Regulation

The Neurovisceral Integration Model posits that shared neural networks support the effective regulation of emotions and heart rate, with heart rate variability (HRV) serving as an objective, peripheral index of prefrontal inhibitory control. Prior neuroimaging studies have predominantly examined both HRV and associated neural functional connectivity at rest, as opposed to contexts that require active emotion regulation. The present study sought to extend upon previous resting-state functional connectivity findings, examining task-related HRV and corresponding amygdala functional connectivity during a cognitive reappraisal task. Seventy adults (52 older and 18 younger adults, 18-84 years, 51% male) received instructions to cognitively reappraise negative affective images during functional MRI scanning. HRV measures were derived from a finger pulse signal throughout the scan. During the task, younger adults exhibited a significant inverse association between HRV and amygdala-medial prefrontal cortex (mPFC) functional connectivity, in which higher task-related HRV was correlated with weaker amygdala-mPFC coupling, whereas older adults displayed a slight positive, albeit non-significant correlation. Furthermore, voxelwise whole-brain functional connectivity analyses showed that higher task-based HRV was linked to weaker right amygdala-posterior cingulate cortex connectivity across older and younger adults, and in older adults, higher task-related HRV correlated positively with stronger right amygdala-right ventrolateral prefrontal cortex connectivity. Collectively, these findings highlight the importance of assessing HRV and neural functional connectivity during active regulatory contexts to further identify neural concomitants of HRV and adaptive emotion regulation.

Planning, conducting, and analyzing a psychophysiological experiment on challenge and threat: A comprehensive tutorial

The biopsychosocial model of challenge and threat (BPS-CT) is a powerful framework linking psychological processes to reliable patterns of cardiovascular responses during motivated performance situations. Specifically, the BPS-CT poses challenge and threat as two motivational states that can emerge in response to a demanding, self-relevant task, where greater challenge arises when perceived resources are higher than demands, and greater threat arises when perceived resources are lower than demands. By identifying unique patterns of physiological responses associated with challenge and threat, respectively, the BPS-CT affords insight into subjective appraisals of resources and demands, and their determinants, during motivated performance situations. Despite its broad utility, lack of familiarity with physiological concepts and difficulty with identifying clear guidelines in the literature are barriers to wider uptake of this approach by behavioral researchers. Our goal is to remove these barriers by providing a comprehensive, step-by-step tutorial on conducting an experiment using the challenge and threat model, offering concrete recommendations for those who are new to the method, and serving as a centralized collection of resources for those looking to deepen their understanding. The tutorial spans five parts, covering theoretical introduction, lab setup, data collection, data analysis, and appendices offering additional details about data analysis and equipment. With this, we aim to make challenge and threat research, and the insights it offers, more accessible to researchers throughout the behavioral sciences.

Does anxiety explain why math-anxious people underperform in math?

Math-anxious people consistently underperform in math. The most widely accepted explanation for why this underperformance occurs is that math-anxious people experience heightened anxiety when faced with math, and this in-the-moment anxiety interferes with performance. Surprisingly, this explanation has not been tested directly. Here, using both self-report and physiological indices of anxiety, we directly test how much in-the-moment anxiety explains math-anxious underperformance. Results indicate that in-the-moment anxiety indeed explains why math-anxious people underperform-but only partially, suggesting a need to seriously consider alternative mechanisms. Results also showed that while some highly math-anxious individuals-those with high levels of heart rate variability-experienced less in-the-moment anxiety, they nevertheless performed no better at math. For these individuals, math-anxious underperformance must occur for reasons unrelated to in-the-moment anxiety. More broadly, our findings point to substantial individual heterogeneity in the mechanisms underlying math-anxious underperformance. Accounting for this mechanistic heterogeneity may prove vital for optimally boosting math performance in math-anxious individuals.

Racial differences in sympathetic nervous system indicators: Implications and challenges for research

Growing evidence indicates the presence of racial differences in sympathetic nervous system (SNS) functioning, yet the nature of these differences is unclear and appears to vary across different indices of SNS activity. Moreover, racial differences among commonly used indices of SNS activity are under-investigated. This systematic review examines racial differences among widely used resting SNS indices, such as electrodermal activity (EDA), pre-ejection period (PEP), and salivary alpha-amylase (sAA). Our review reveals that Black participants have consistently been found to display lower resting EDA compared to White participants. The few studies that have investigated or reported racial differences in PEP and sAA yield mixed findings about whether racial differences exist. We discuss potential reasons for racial differences in SNS activity, such as index-specific factors, lab confounds, psychosocial environmental factors, and their interactions. We outline a framework characterizing possible contributors to racial differences in SNS functioning. Lastly, we highlight the implications of several definitional, analytic, and interpretive issues concerning the treatment of group differences in psychophysiological activity and provide future recommendations.

An examination of autonomic and facial responses to prototypical facial emotion expressions in psychopathy

Meta-analyses have found that people high in psychopathy categorize (or “recognize”) others’ prototypical facial emotion expressions with reduced accuracy. However, these have been contested with remaining questions regarding the strength, specificity, and mechanisms of this ability in psychopathy. In addition, few studies have tested holistically whether psychopathy is related to reduced facial mimicry or autonomic arousal in response to others’ dynamic facial expressions. Therefore, the current study presented 6 s videos of a target person making prototypical emotion expressions (anger, fear, disgust, sadness, joy, and neutral) to N = 88 incarcerated adult males while recording facial electromyography, skin conductance response (SCR), and heart rate. Participants identified the emotion category and rated the valence and intensity of the target person’s emotion. Psychopathy was assessed via the Psychopathy Checklist-Revised (PCL-R). We predicted that overall PCL-R scores and scores for the interpersonal/affective traits, in particular, would be related to reduced emotion categorization accuracy, valence ratings, intensity ratings, facial mimicry, SCR amplitude, and cardiac deceleration in response to the prototypical facial emotion expressions. In contrast to our hypotheses, PCL-R scores were unrelated to emotion categorization accuracy, valence ratings, and intensity ratings. Stimuli failed to elicit facial mimicry from the full sample, which does not allow drawing conclusions about the relationship between psychopathy and facial mimicry. However, participants displayed general autonomic arousal responses, but not to prototypical emotion expressions per se. PCL-R scores were also unrelated to SCR and cardiac deceleration. These findings failed to identify aberrant behavioral and physiological responses to prototypical facial emotion expressions in relation to psychopathy.

Validation of a new impedance cardiography analysis algorithm for clinical classification of stress states

Pre-ejection period (PEP) is an index of sympathetic nervous system activity that can be computed from electrocardiogram (ECG) and impedance cardiogram (ICG) signals, but sensitive to speech/motion artifact. We sought to validate an ICG noise removal method, three-stage ensemble-average algorithm (TEA), in data acquired from a clinical trial comparing active versus sham non-invasive vagal nerve stimulation (tcVNS) after standardized speech stress. We first compared TEA's performance versus the standard conventional ensemble-average algorithm (CEA) approach to classify noisy ICG segments. We then analyzed ECG and ICG data to measure PEP and compared group-level differences in stress states with each approach. We evaluated 45 individuals, of whom 23 had post-traumatic stress disorder (PTSD). We found that the TEA approach identified artifact-corrupted beats with intraclass correlation coefficient > 0.99 compared to expert adjudication. TEA also resulted in higher group-level differences in PEP between stress states than CEA. PEP values were lower in the speech stress (vs. baseline rest) group using both techniques, but the differences were greater using TEA (12.1 ms) than CEA (8.0 ms). PEP differences in groups divided by PTSD status and tcVNS (active vs. sham) were also greater when using the TEA versus CEA method, although the magnitude of the differences was lower. In conclusion, TEA helps to accurately identify noisy ICG beats during speaking stress, and this increased accuracy improves sensitivity to group-level differences in stress states compared to CEA, suggesting greater clinical utility.

Utility of an Isotonic Beverage on Hydration Status and Cardiovascular Alterations

This study determined the beverage hydration index (BHI) and postprandial cardiac autonomic activity after consuming an isotonic beverage (IB) compared to distilled water (DW). Twenty-two participants (50% female; mean ± SD; age, 27 ± 3 year; height, 169.1 ± 12.6 cm; weight, 73.3 ± 13.8 kg; BF%, 23 ± 10%) completed two experimental trials where they consumed 1 L DW or an IB; after which urine volume and cardiac autonomic activity was measured through 240 min. Cardiac autonomic activity was quantified using heart rate (HR), log transformed heart rate variability measures (root mean square of successive R–R intervals; RMSSD; low frequency, LF; and high frequency, HF) and systolic time intervals (pre-ejection period, PEP). BHI was significantly greater after IB consumption at min 0 (MD [95% CI]; 1.31 [0.35, 2.27]), 180 min (0.09 [0.022, 0.16]), and 240 min (0.1 [0.03, 0.17]) compared to DW (p = 0.031). Net fluid balance was significantly greater in IB than DW at 180 min (90 [−16.80, 196.81]) and 240 min (106 [−13.88, 225.88]) (p = 0.037). HR decreased over time in both beverage trials but was higher following IB ingestion at 0 min (3.9 [−2.42, 10.22]), 30 min (5.3 [−0.94, 11.54]), and 60 min (2.7 [−3.42, 8.82]) (p = 0.0002). lnHF was greater 30 min post DW ingestion compared to IB (0.45 [−0.23, 1.13]) (p = 0.039). IB promotes greater fluid retention capacity compared to DW within 4 hours of consumption. The variations in cardiac autonomic measures may warrant further investigation in clinical populations (i.e., patients with autonomic failure).

Physiological and Psychological Effects of Volatile Organic Compounds from Dried Common Rush (Juncus effusus L. var. decipiens Buchen.) on Humans

This study compared the participants’ physiological responses and subjective evaluations of air scented with different concentrations of common rush (Juncus effusus L. var. decipiens Buchen.) (30 g and 15 g, with fresh air as a control). We asked 20 participants to complete a series of visual discrimination tasks while inhaling two different air samples. We evaluated (1) brain activity, (2) autonomic nervous activity, and (3) blood pressure and pulse rate, (4) in combination with self-evaluation. In addition, we quantified the concentrations of volatile organic compounds. The participants reported the scent to be sour, pungent, and smelly; this impression was likely caused by hexanal and acetic acid. Although the self-evaluations showed that participants did not enjoy the scent, their alpha amplitudes of electroencephalogram and parasympathetic nervous activity were increased, suggesting that participants were relaxed in this atmosphere. Moreover, a lower concentration resulted in a greater induction of relaxation. While the air was not pleasant-smelling, the volatile organic compounds present had a positive psychophysiological impact.

β-Adrenergic Contributions to Emotion and Physiology During an Acute Psychosocial Stressor

OBJECTIVE

β-Adrenergic receptor signaling, a critical mediator of sympathetic nervous system influences on physiology and behavior, has long been proposed as one contributor to subjective stress. However, prior findings are surprisingly mixed about whether β-blockade (e.g., propranolol) blunts subjective stress, with many studies reporting no effects. We reevaluated this question in the context of an acute psychosocial stressor with more comprehensive measures and a larger-than-typical sample. We also examined the effects of β-blockade on psychophysiological indicators of sympathetic and parasympathetic nervous system reactivity, given that β-blockade effects for these measures specifically under acute psychosocial stress are not yet well established.

METHODS

In a double-blind, randomized, placebo-controlled study, 90 healthy young adults received 40 mg of the β-blocker propranolol or placebo. Participants then completed the Trier Social Stress Test, which involved completing an impromptu speech and difficult arithmetic in front of evaluative judges. Self-reported emotions and appraisals as well as psychophysiology were assessed throughout.

RESULTS

Propranolol blunted Trier Social Stress Test preejection period reactivity (b = 9.68, p = .003), a marker of sympathetic nervous system activity, as well as salivary α-amylase reactivity (b = -0.50, p = .006). Critically, propranolol also blunted negative, high arousal emotions in response to the stressor (b = -0.22, p = .026), but cognitive appraisals remained intact (b values < -0.17, p values > .10).

CONCLUSIONS

These results provide updated experimental evidence that β-adrenergic blockade attenuates negative, high arousal emotions in response to a psychosocial stressor while also blunting sympathetic nervous system reactivity. Together, these findings shed light on the neurophysiological mechanisms by which stressors transform into the subjective experience we call "stress."Trial Registration: ClinicalTrials.gov Identifier: NCT02972554.

Indoor nature exposure and influence on physiological stress markers

Spending time in nature is beneficial for stress reduction and recovery. Using the properties of biophilic design, this study examined the influence of a nature-based indoor environment on physiological stress systems. An experimental study was designed to assess the influence of indoor natural elements on autonomic activity (heart rate variability or HRV), self-reported environmental assessments. No differences in heart rate variability were found between participants assigned to either condition. The room with natural elements was rated more positively than the room without natural elements. Participant preference had more impact on changes in HRV for participants without exposure to natural elements. The results suggest that natural elements in indoor environments may influence the regulation of stress response via environmental preference.Abbreviations: ANCOVA: Analysis of Covariance; ANS: Autonomic Nervous System; AVNN: Average of NN; DST: Digit Span Test; EAS: Environmental Assessment Scale; ECG: Electrocardiograph; fMRI: Functional magnetic resonance imaging; HF: High Frequency; HRV: Heart Rate Variability; INE: Indoor Nature Exposure; NR: Nature-Relatedness Scale; PANAS: Positive and Negative Affect Schedule; SAM: Search and Memory Test; SLSI: Student Life Stress Inventory; SMT: Sentence Making Test.

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.

Correspondence of parasympathetic-mediated heart rate variability derived from electrocardiogram and photoplethysmography signals in ethnically diverse adolescents

The reliable and valid assessment of heart rate variability (HRV) is important to understanding autonomic functioning in youth. However, use of electrocardiogram (ECG) signals to derive estimates of parasympathetic-mediated HRV may present logistical barriers in applied settings. Thus, this study investigated the concordance between high-frequency HRV [HF-HRV] and root mean square of successive differences [RMSSD] derived from ECG and photoplethysmography (PPG) signals during a video baseline, resting baseline, and mental arithmetic among an ethnically diverse sample of ninety-six youths (M_age = 13.84; 51% male; 62.5% ethnic minority). Results showed moderate to almost perfect agreement between PPG- and ECG- derived HF-HRV and RMSSD for video and resting baselines (Lin's correlations ranged from 0.93 to 0.99) and limits of agreement (LoA) ranging from -0.48 to 0.58 (HF-HRV) and - 11.37 to 9.32 (RMSSD). Conversely, we found poor to moderate agreement for the mental arithmetic task (Lin's correlations ranged from 0.88 to 0.91) and LoA ranging from -0.68 + 0.94 (HF-HRV) and - 17.58 + 20.69 (RMSSD), though we did find ethnic minority youth had higher and moderate Lin's correlations (0.93 to 0.94). Overall, there was a bias towards higher HF-HRV and RMSSD values with PPG. Findings suggest that PPG-derived HF-HRV and RMSSD may be viable alternatives for ECG in baseline conditions, but tasks requiring movement or eliciting mild stress responses may result in less than perfect values and missing data patterns. It is imperative that future studies replicate these findings in other ethnically diverse youth samples and expand to younger children and applied settings.

Physiological Stress Response Reactivity Mediates the Link Between Emotional Abuse and Youth Internalizing Problems

Youth who are raised in emotionally abusive families are more likely to have poor mental health outcomes such as depression and anxiety. However, the mechanisms of this association are unclear. The present study utilized a longitudinal sample of low-SES youth (N = 101, M_ageT1 = 10.24) to examine stress response reactivity (i.e. vagal withdrawal, sympathetic activation, and hypothalamic-pituitary-adrenal [HPA] axis activation) as mediators between emotional abuse and prospective youth internalizing symptoms. Results indicated that blunted HPA reactivity to a laboratory social stress task mediated the association between emotional abuse and youth internalizing symptoms. Emotional abuse was also associated with blunted parasympathetic nervous system activity (i.e. less vagal withdrawal than average). In sum, emotional abuse is a potent risk factor for youth internalizing symptoms, and this link may be mediated via dysregulation in physiological stress response systems. Primary prevention of childhood emotional abuse and secondary prevention programs that target self-regulation skills may reduce rates of youth internalizing symptoms and disorders.

Heart Rate Variability and Circulating Inflammatory Markers in Midlife

Theoretical perspectives and empirical evidence suggest that the parasympathetic nervous system engages in active monitoring and moderating of inflammatory processes. A clearer understanding of the bidirectional communication between the parasympathetic nervous system and the immune system could lead to novel clinical interventions for inflammatory illnesses. The current study used a large (N ​= ​836) nationally representative sample of adults in the United States to investigate the associations between resting parasympathetic modulation of the heart, indexed through both high frequency heart rate variability (HF-HRV) and low frequency heart rate variability (LF-HRV), and six circulating markers of inflammation. Statistical analyses revealed robust inverse associations of HF-HRV with interleukin-6 (IL6), C-reactive protein (CRP), and fibrinogen, with or without covariate adjustment. Similar inverse associations were observed between LF-HRV and IL6 and CRP. No significant associations were observed between HRV and either inflammatory adhesion molecules (E-selectin, intracellular adhesion molecule-1) or soluble IL6 receptor. Results are consistent with the cholinergic anti-inflammatory pathway and suggest that parasympathetic modulation of inflammation through the vagus nerve may act on specific inflammatory molecules more than others.

A Close Examination of the Use of Systolic Time Intervals in the Calculation of Impedance Derived Cardiac Autonomic Balance and Regulation

Traditionally, impedance derived measures of cardiac autonomic balance (CAB) and regulation (CAR) are calculated using indices of heart rate variability (HRV) that primarily reflect parasympathetic nervous system activity (e.g., high-frequency HRV | HF-HRV) and pre-ejection period (PEP; a systolic time interval and measure of sympathetic activity). However, HF-HRV and PEP are considered measures of chronotropic and inotropic cardiac influence, respectively. Left ventricular ejection time (LVET) is a systolic time interval that reflects sympathetic chronotropic influence, and therefore may be a more appropriate measure for calculating CAB and CAR compared to PEP. Thus, the current study evaluates both PEP and LVET in the calculation of CAB and CAR. Data from 158 healthy participants (mean age = 19.09 years old, SD = 1.84 years) were available for analyses. CAB and CAR values were calculated using both HF-HRV and the root mean square of successive differences, in addition to both PEP and LVET, in accordance with previously established guidelines. Analyses showed that correlations were significantly weaker between CAB and CAR calculated using LVET for both HF (z = 5.12, p < 0.001) and RMSSD (z = 5.26, p < 0.001) than with PEP. These data suggest that LVET, compared to PEP, provides better “autonomic space” as evidenced by a lack of correlation between CAB and CAR computed using LVET. We stress that future research consider calculating CAB and CAR using chronotropic measures for both parasympathetic and sympathetic activity, as doing so may yield more accurate and independent measures of cardiac autonomic activity compared to a mixture of inotropic (i.e., PEP) and chronotropic (i.e., HF-HRV) measures.

Respiratory sinus arrhythmia reactivity in anxiety and posttraumatic stress disorder: A review of literature

Respiratory sinus arrhythmia (RSA) reactivity is thought to indicate how adaptively one responds to stress. RSA reactivity has been examined across anxiety disorders and posttraumatic stress disorder (PTSD), to better understand the psychophysiological stress response of these disorders. The current state of the literature is mixed, and the association between RSA reactivity and PTSD/anxiety is unclear. This review examines RSA reactivity in response to laboratory stressor tasks across samples with anxiety and PTSD. Results indicated a complex literature that may suggest an association between anxiety/PTSD and RSA reactivity. There is evidence to suggest a pattern of heightened RSA withdrawal in PTSD and trait anxious samples. There was little evidence to suggest a heightened RSA withdrawal pattern in other anxiety disorders. This review also highlights methodological considerations which may allow for clearer interpretations of RSA reactivity. The current literature includes heterogeneity across stressor tasks, RSA measures, and comorbidities that complicates interpretation of results. Studies using samples with comorbid depression produce more consistent evidence of heightened RSA withdrawal in anxiety/PTSD. Future directions for understanding the contribution of these variables (i.e., stressor tasks, RSA measures, comorbid depression) and mechanisms contributing to the possible association between RSA reactivity and anxiety/PTSD are considered.

Investigating the relationship between emotional granularity and cardiorespiratory physiological activity in daily life

Emotional granularity describes the ability to create emotional experiences that are precise and context-specific. Despite growing evidence of a link between emotional granularity and mental health, the physiological correlates of granularity have been under-investigated. This study explored the relationship between granularity and cardiorespiratory physiological activity in everyday life, with particular reference to the role of respiratory sinus arrhythmia (RSA), an estimate of vagal influence on the heart often associated with positive mental and physical health outcomes. Participants completed a physiologically triggered experience-sampling protocol including ambulatory recording of electrocardiogram, impedance cardiogram, movement, and posture. At each prompt, participants generated emotion labels to describe their current experience. In an end-of-day survey, participants elaborated on each prompt by rating the intensity of their experience on a standard set of emotion adjectives. Consistent with our hypotheses, individuals with higher granularity exhibited a larger number of distinct patterns of physiological activity during seated rest, and more situationally precise patterns of activity during emotional events: granularity was positively correlated with the number of clusters of cardiorespiratory physiological activity discovered in seated rest data, as well as with the performance of classifiers trained on event-related changes in physiological activity. Granularity was also positively associated with RSA during seated rest periods, although this relationship did not reach significance in this sample. These findings are consistent with constructionist accounts of emotion that propose concepts as a key mechanism underlying individual differences in emotional experience, physiological regulation, and physical health.

Adrenergic Tone as an Intermediary in the Temperament Syndrome Associated With Flight Speed in Beef Cattle

The temperament of farm animals can influence their resilience to everyday variations within the managed production environment and has been under strong direct and indirect selection during the course of domestication. A prominent objective measure used for assessing temperament in beef cattle is the behavioral flight response to release from confinement in a crush or chute. This behavioral measure, termed flight speed (also known as escape velocity) is associated with physiological processes including body temperature, feeding behavior, growth rate, carcass composition, immune function, and health outcomes. This review examines the functional links between this suite of traits and adrenergic activity of the sympathetic nervous system and the adrenomedullary hormonal system. It is suggested that flight speed is the behavioral aspect of an underlying “flightiness” temperament syndrome, and that elevated adrenergic tone in animals with a high level of flightiness (i.e., flighty animals) tunes physiological activities toward a sustained “fight or flight” defense profile that reduces productivity and the capacity to flourish within the production environment. Nonetheless, despite a common influence of adrenergic tone on this suite of traits, variation in each trait is also influenced by other regulatory pathways and by the capacity of tissues to respond to a range of modulators in addition to adrenergic stimuli. It is suggested that tuning by adrenergic tone is an example of homeorhetic regulation that can help account for the persistent expression of behavioral and somatic traits associated with the flight speed temperament syndrome across the life of the animal. At a population level, temperament may modulate ecological fit within and across generations in the face of environmental variability and change. Associations of flight speed with the psychological affective state of the animal, and implications for welfare are also considered. The review will help advance understanding of the developmental biology and physiological regulation of temperament syndromes.

Correlation of sympathetic and parasympathetic nervous system activity during rest and acute stress tasks

Autonomic nervous system (ANS) activity is a core and central component of emotion and motivated action. The myriad social and cognitive challenges faced by humans require flexible modulation of ANS activity for different contexts. In this study, simultaneous activity of the parasympathetic and sympathetic nervous system was measured using respiratory sinus arrhythmia (RSA) and pre-ejection period (PEP), respectively. Samples combined four previous studies (N = 325, 63% female, aged 15-55) in which RSA and PEP were collected continuously during a resting baseline and an acute stressor, the Trier Social Stress Task. The concurrent relation between RSA and PEP responses was modelled in order to determine the extent to which SNS and PNS activity is correlated across the task within and between participants, and whether this correlation was moderated by age, race, sex, or baseline RSA and PEP. Overall, RSA and PEP were reciprocally coupled. However, recovery from a stressor was characterized by coactivation. Individuals also vary in the extent to which their SNS and PNS are reciprocally coupled; women, younger adults, and individuals with higher baseline RSA showed more reciprocal coupling than men, older adults, and those with lower baseline RSA, respectively, reflecting greater coordination of physiological responding in the former groups.

Maturation of the Cardiac Autonomic Nervous System Activity in Children and Adolescents

Background

Despite the increasing interest in cardiac autonomic nervous activity, the normal development is not fully understood. The main aim was to determine the maturation of different cardiac sympathetic‐(SNS) and parasympathetic nervous system (PNS) activity parameters in healthy patients aged 0.5 to 20 years. A second aim was to determine potential sex differences.

Methods and Results

Five studies covering the 0.5‐ to 20‐year age range provided impedance‐ and electrocardiography recordings from which heart rate, different PNS‐parameters (eg, respiratory sinus arrhythmia) and an SNS‐parameter (pre‐ejection period) were collected. Age trends were computed in the mean values across 12 age‐bins and in the age‐specific variances. Age was associated with changes in mean and variance of all parameters. PNS‐activity followed a cubic trend, with an exponential increase from infancy, a plateau phase during middle childhood, followed by a decrease to adolescence. SNS‐activity showed a more linear trend, with a gradual decrease from infancy to adolescence. Boys had higher SNS‐activity at ages 11 to 15 years, while PNS‐activity was higher at 5 and 11 to 12 years with the plateau level reached earlier in girls. Interindividual variation was high at all ages. Variance was reasonably stable for SNS‐ and the log‐transformed PNS‐parameters.

Conclusions

Cardiac PNS‐ and SNS‐activity in childhood follows different maturational trajectories. Whereas PNS‐activity shows a cubic trend with a plateau phase during middle childhood, SNS‐activity shows a linear decrease from 0.5 to 20 years. Despite the large samples used, clinical use of the sex‐specific centile and percentile normative values is modest in view of the large individual differences, even within narrow age bands.

Brief Report: Reduced Heart Rate Variability in Children with Autism Spectrum Disorder

Dysregulation of the autonomic nervous system (ANS), which can be indexed by heart rate variability (HRV), has been posited to contribute to core features of autism spectrum disorder (ASD). However, the relationship between ASD and HRV remains uncertain. We assessed tonic and phasic HRV of 21 children with ASD and 21 age- and IQ-matched typically developing (TD) children and examined (1) group differences in HRV and (2) associations between HRV and ASD symptomatology. Children with ASD showed significantly lower tonic HRV, but similar phasic HRV compared to TD children. Additionally, reduced tonic HRV was associated with atypical attentional responsivity in ASD. Our findings suggest ANS dysregulation is present in ASD and may contribute to atypical attentional responses to sensory stimulation.

Cardiac sympathetic activity during recovery as an indicator of sympathetic activity during task performance

The goals of this research were to analyze cardiac sympathetic recovery patterns and evaluate whether sympathetic cardiac responses to a task challenge can be predicted using residual cardiac activity measured directly after the task (that is, during the recovery period). In two studies (total N = 181), we measured cardiac sympathetic activity, quantified as pre-ejection period and RB interval, during both task performance and the 2-min recovery period following the task. Additional analyses examined effects on the RZ interval. We found that sympathetic recovery from a task was rather quick: Cardiovascular recovery occurred within the first 30 s of the recovery period. Nevertheless, residual cardiac activity during the recovery period had predictive power for task-related cardiac activity. This suggests that sympathetic cardiac activity during recovery may serve as a useful indicator of task-related cardiac sympathetic activity. We discuss the implications of these findings for practical applications and the design of future studies.

The autonomic nervous system in its natural environment: Immersion in nature is associated with changes in heart rate and heart rate variability

Stress Recovery Theory (SRT) suggests that time spent in nature reduces stress. While many studies have examined changes in stress physiology after exposure to nature imagery, nature virtual reality, or nature walks, this study is the first to examine changes in heart rate (HR) and vagally mediated HR variability, as assessed by Respiratory Sinus Arrythmia (RSA), after a longer duration of nature exposure. Consistent with SRT, we hypothesized that immersion in nature would promote stress recovery, as indexed by an increase in RSA and a decrease in HR. We also predicted that exposure to nature would improve self-reported mood. We used a within-subjects design (N = 67) to assess changes in peripheral physiology before, during, and after a 5-day nature trip. Results demonstrated a significant decrease in RSA and a significant increase in HR during the trip compared to before or after the trip, suggesting that immersion in nature is associated with a shift toward parasympathetic withdrawal and possible sympathetic activation. These results were contrary to our hypotheses and may suggest increased attentional intake or presence of emotions associated with an increase in sympathetic activation. We also found an improvement in self-reported measures of mood during the trip compared to before or after the trip, confirming our hypotheses and replicating previous research. Implications of this study are discussed in the context of SRT.

An autonomic nervous system context of harsh parenting and youth aggression versus delinquency

Harsh parenting is a significant predictor of youth aggression and delinquency. However, not every child exposed to adverse parenting develops such problem behaviors. Recent developmental evolutionary models suggest that variability in stress response reactivity to parenting, reflected by autonomic nervous system (ANS) functioning, may affect the impact of adverse parenting on youth behavioral adjustment. The aim of the present study was to investigate whether the parasympathetic and sympathetic branches of the ANS moderate the association between parenting and aggressive and delinquent behaviors. The study sample included low-income, ethnically diverse preadolescents (M = 10.28 years old; N = 101) and their caregivers. Direct effects were found from basal RSA to delinquent behaviors. In addition, harsh parenting predicted increased youths' aggressive and delinquent behaviors in the context of high RSA withdrawal and increased youths' delinquent behaviors in the context of shortened basal PEP. Implications for prevention and intervention are discussed.

Autonomic nervous system activity predicts increasing serum cytokines in children

Systemic inflammation is associated with increased risk for prevalent and costly diseases, and animal models implicate the autonomic nervous system in the control of inflammatory processes. In humans, research on autonomic-immune connections has been much more limited, and has focused on single branch autonomic measures (i.e., either parasympathetic or sympathetic). The current study utilized cardiac autonomic balance (CAB), derived from dual-branch cardiac autonomic recordings, to test the relation between resting autonomic function and inflammatory reactivity to challenge in children.

METHODS

Participants included 96 children (51 boys, 45 girls) ages 9-11 years (mean age = 9.93 years, SD = 0.57 years). CAB values were calculated from standardized measures of parasympathetic and sympathetic activity, namely resting respiratory sinus arrhythmia and pre-ejection period data, respectively. Children provided two blood samples, one before and one following exposure to an acute social stressor or control condition. Serum was assayed for four cytokines that orchestrate inflammation: interleukin-6 (IL6), interleukin-8 (IL8), interleukin-10 (IL10), and tumor necrosis factor-alpha (TNFa).

RESULTS

We discovered large individual differences in inflammatory marker production across children, and no average main effect of stress condition. CAB significantly predicted these individual differences, such that children lower on CAB showed increasing serum cytokines from time 1 to time 2. In contrast, children with greater CAB tended to show declining inflammatory markers across the session.

DISCUSSION

Low cardiac autonomic balance (i.e., the combination of low parasympathetic and high sympathetic activity) may be a useful marker of proinflammatory tendencies in children, suggesting novel paths for early risk detection and intervention.

Response Inhibition, Response Execution, and Emotion Regulation among Children with Attention-Deficit/Hyperactivity Disorder

Attention-deficit/hyperactivity disorder (ADHD) is associated with deficits in response inhibition, response execution, and emotion regulation. However, the nature of the associations among these deficits remains unclear. Thus, this study examines these associations using a multi-method design. One hundred sixty-six children (aged 5-13 years; 66.3% male; 75 with ADHD) completed two conditions (i.e., neutral and fear) of an emotional go/no-go task. Parasympathetic-based regulation was indexed via respiratory sinus arrhythmia (RSA), and sympathetic-based reactivity was indexed via cardiac pre-ejection period (PEP). Overall, children exhibited more difficulty with response execution (i.e., more omission errors, fewer correct go responses) and less difficulty with response inhibition (i.e., fewer commission errors, more correct no-go responses) during the fear condition than the neutral condition. Children with ADHD displayed more difficulty with response execution during the fear condition compared to typically developing youth. Additionally, children with ADHD displayed parasympathetic-based dysregulation (i.e., RSA increase from baseline) and reduced sympathetic-based reactivity (i.e., PEP lengthening) compared to typically developing youth across task conditions. In sum, children with ADHD demonstrate greater difficulty with response execution during emotionally salient contexts, as well as parasympathetic-based emotion dysregulation. Future work should examine these associations longitudinally with the aim of predicting impairment and treatment response in youth with ADHD.

Context-aware experience sampling reveals the scale of variation in affective experience

Emotion research typically searches for consistency and specificity in physiological activity across instances of an emotion category, such as anger or fear, yet studies to date have observed more variation than expected. In the present study, we adopt an alternative approach, searching inductively for structure within variation, both within and across participants. Following a novel, physiologically-triggered experience sampling procedure, participants' self-reports and peripheral physiological activity were recorded when substantial changes in cardiac activity occurred in the absence of movement. Unsupervised clustering analyses revealed variability in the number and nature of patterns of physiological activity that recurred within individuals, as well as in the affect ratings and emotion labels associated with each pattern. There were also broad patterns that recurred across individuals. These findings support a constructionist account of emotion which, drawing on Darwin, proposes that emotion categories are populations of variable instances tied to situation-specific needs.

Features of autonomic cardiovascular control during cognition in major depressive disorder

Previous research has suggested reduced parasympathetic cardiac regulation during cognitive activity in major depressive disorder (MDD). However, little is known about possible abnormalities in sympathetic control and cardiovascular reactivity. This study aimed to provide a comprehensive analysis of autonomic cardiovascular control in the context of executive functions in MDD. Thirty six MDD patients and 39 healthy controls participated. Parameters of sympathetic (pre-ejection period, PEP) and parasympathetic control (high and low frequency heart rate variability, HF HRV, LF HRV; and baroreflex sensitivity, BRS) as well as RR interval were obtained at rest and during performance of executive function tasks (number-letter task, n-back task, continuous performance test, and Stroop task). Patients, as compared to controls, exhibited lower HF HRV and LF HRV during task execution and smaller shortenings in PEP and RR interval between baseline and tasks. They displayed longer reaction times during all conditions of the tasks and more omission errors and false alarms on the continuous performance test. In the total sample, on-task HF HRV, LF HRV and BRS, and reactivity in HF HRV, LF HRV, and PEP, were positively associated with task performance. As performance reduction arose independent of executive function load of the tasks, the behavioral results reflect impairments in attention and processing speed rather than executive dysfunctions in MDD. Abnormalities in cardiovascular control during cognition in MDD appear to involve both divisions of the autonomic nervous system. Low tonic parasympathetic control and blunted sympathetic reactivity imply reduced physiological adjustment resources and, by extension, provide suboptimal conditions for cognitive performance.

The effects of testosterone on the physiological response to social and somatic stressors

Higher testosterone levels in males have previously been linked to decreased stress reactivity, but in other cases, testosterone has been reported to increase the stress response. We addressed these inconsistencies in a placebo-controlled single-dose testosterone administration study, in which 120 male participants were randomly assigned to undergo a cold-pressor test (CPT, a non-social somatic stressor), a socially evaluated cold-pressor test (SECPT, a social-somatic stressor), or a lukewarm water test (LWT, a non-stressful control condition). Throughout the experiment, blood pressure and interbeat intervals were measured continuously, and saliva samples for hormonal analyses were taken repeatedly at predefined time points. When comparing the groups treated with placebo, the SECPT elicited a larger increase in the systolic blood pressure than CPT, in agreement with previous studies. However, testosterone administration altered this pattern. Compared to placebo, testosterone increased systolic blood pressure during the CPT, whereas the opposite effect was found during the SECPT. Cortisol reactivity was not affected by testosterone administration. The CAG repeat polymorphism of the androgen receptor gene was unrelated to the effects of testosterone on the stress response, but it was correlated with blood pressure across the whole sample. Our findings demonstrate that testosterone's effects on the stress response are dependent on the social context. Testosterone's ability to flexibly influence the response to stressors may be an important mechanism through which the hormone promotes adaptive behavior. Our results are also in line with research showing that testosterone decreases social anxiety and suggest it may help to modulate the effects of stress in socially challenging situations.

Reflecting on Existential Threats Elicits Self-Reported Negative Affect but No Physiological Arousal

There is mixed evidence whether reflecting on an existential threat increases negative affect and thereby elicits subjective arousal and physiological activation. Additionally, it is debated whether different existential and non-existential threats elicit different arousal responses, although systematic comparisons are lacking. The current study explored affective, subjective, and physiological arousal responses while comparing several existential threats with a non-existential threat and with a control condition. One-hundred-and-seventy-one undergraduate students were randomly allocated to one of four existential threat conditions: mortality salience (MS), freedom restriction, uncontrollability, and uncertainty; or to the non-existential threat condition: social-evaluative threat (SET); or to a control condition (TV salience). Self-reported positive/negative affect was measured before and after reflection, while subjective arousal and physiological activation (electrodermal, cardiovascular, and respiratory) were measured on a high time-scale during baseline and reflection. Results showed larger increases in self-reported negative affect, as compared to the control condition, for all existential threat conditions, while there were no differences between the control condition and threat conditions regarding positive affect, subjective arousal, skin conductance, respiratory rate, and respiratory sinus arrythmia. There were subtle differences between existential and non-existential threat conditions, most notably in affective responses. Correlations showed positive associations between negative affect and subjective arousal and between trait avoidance and subjective arousal. This study is the first to systematically compare affective, subjective, and physiological changes in arousal due to reflecting on different existential threats, as well as one non-existential threat. We showed that, as compared to a control condition, reflecting on threats has a large impact on negative affect, but no significant impact on positive affect, subjective arousal, and physiological activation.

Autonomic influences on heart rate during marital conflict: Associations with high frequency heart rate variability and cardiac pre-ejection period

Psychosocial factors predict the development and course of cardiovascular disease, perhaps through sympathetic and parasympathetic mechanisms. At rest, heart rate (HR) is under parasympathetic control, often measured as high-frequency heart rate variability (HF-HRV). During stress, HR is influenced jointly by parasympathetic and sympathetic processes, the latter often quantified as pre-ejection period (PEP). In studies of cardiovascular risk factors that involve social interaction (e.g. marital conflict), HF-HRV might be altered by speech artifacts, weakening its validity as a measure of parasympathetic activity. To evaluate this possibility, we tested associations of HF-HRV and PEP with HR at rest and across periods of marital conflict interaction that varied in experimentally-manipulated degrees of speech in 104 couples. At rest, only HF-HRV was independently related to HR, for both husbands and wives. During speaking, listening, and recovery periods, husbands' and wives' HF-HRV and PEP change independently predicted HR change. These findings support interpretation of HF-HRV as a parasympathetic index during stressful social interactions that may confer risk for cardiovascular disease.

Controlling the uncontrolled: Are there incidental experimenter effects on physiologic responding?

The degree to which experimenters shape participant behavior has long been of interest in experimental social science research. Here, we extend this question to the domain of peripheral psychophysiology, where experimenters often have direct, physical contact with participants, yet researchers do not consistently test for their influence. We describe analytic tools for examining experimenter effects in peripheral physiology. Using these tools, we investigate nine data sets totaling 1,341 participants and 160 experimenters across different roles (e.g., lead research assistants, evaluators, confederates) to demonstrate how researchers can test for experimenter effects in participant autonomic nervous system activity during baseline recordings and reactivity to study tasks. Our results showed (a) little to no significant variance in participants' physiological reactivity due to their experimenters, and (b) little to no evidence that three characteristics of experimenters that are well known to shape interpersonal interactions-status (using five studies with 682 total participants), gender (using two studies with 359 total participants), and race (in two studies with 554 total participants)-influenced participants' physiology. We highlight several reasons that experimenter effects in physiological data are still cause for concern, including the fact that experimenters in these studies were already restricted on a number of characteristics (e.g., age, education). We present recommendations for examining and reducing experimenter effects in physiological data and discuss implications for replication.

Social-evaluative threat: Stress response stages and influences of biological sex and neuroticism

Social-evaluative threat (SET) - when the self could be negatively judged by others - can cause pronounced responses in the different stress systems: threat/challenge appraisal, the sympathetic (SNS) and parasympathetic (PNS) nervous systems, experienced motivation and affect, and the hypothalamus-pituitary-adrenal (HPA) axis. Here, we utilize a four-stage stress response model to shed light on the complex associations between different stress responses, where earlier stages are hypothesized to predict later stages. Additionally, we take into account important moderators, such as biological sex (controlling for menstrual cycle phase), personality traits (neuroticism and extraversion), and baseline stress levels. Thirty-seven men and 30 women in their luteal phase participated in an impromptu public speaking task to induce SET. Stress responses in four different stages were measured using: self-reported appraisal (threat or challenge, stage 1: S1), cardiovascular measures (pre-ejection period as SNS index, respiratory sinus arrhythmia as PNS index, S2), self-reported motivation and affect (state approach motivation, state anxiety, S3) and endocrine measures (cortisol as HPA index, S4). Stress reactivity was calculated by subtracting individual peaks from baseline. Results showed that SET induced pronounced stress reactivity in stages two to four. Against expectations, self-reported appraisal (S1) or motivation and affect (S3) did not predict later stress reactivity. As hypothesized, increased SNS (but not PNS) reactivity (S2) predicted increased HPA reactivity (S4). Bayesian model comparison confirmed the absence of sex differences in stress reactivity, likely due to controlling for menstrual cycle phase and sex differences in neuroticism levels. Higher trait neuroticism predicted blunted SNS (S2) and HPA (S4) reactivity, while higher baseline stress levels predicted blunted stages two and three reactivity overall. In conclusion, this rigorously controlled experiment partly supports and partly contradicts previous findings regarding associations between stress response stages, and offers new insight into the causes of blunted HPA responses in women.

Reduced caregiving quality measured during the strange situation procedure increases child's autonomic nervous system stress response

BACKGROUND

Dysfunctional maternal behavior has been shown to lead to disturbances in infant's regulatory capacities and alterations in vagal reactivity. We aim to investigate the autonomic nervous system (ANS) response of the child during the strange situation procedure (SSP) in relation to the quality of maternal behavior.

METHODS

Twelve month after birth, 163 mother-child-dyads were investigated during the SSP. Heart rate (HR) and both, the parasympathetic branch (PNS) via the respiratory sinus arrhythmia (RSA) and the sympathetic branch (SNS) via the left ventricular ejection time (LVET) of the ANS were continuously determined during the SSP using electrocardiogram (ECG) and impedance cardiogram (ICG) measures. Maternal behavior was assessed by using the AMBIANCE measure.

RESULTS

The ANS response in infants of mothers with disruptive behavior compared to infants of non-disruptive mothers was significantly altered during the SSP: HR increased especially when infants of disruptive mothers were alone with the stranger (F (1, 161) = 4.15, p = .04) with a significant vagal withdrawal when being in contact with the stranger despite of presence of the mother (F (1, 161) = 5.11, p = .03) and a significant increase in vagal tone during final reunion (F (1, 161) = 3.76, p = .05). HR increase was mainly based on a decrease in LVET (F (1, 161) = 4.08, p = .05) with a maximum infant's HR when the stranger came into the room instead of the mother.

CONCLUSION

Both, SNS and PNS branches of the child are significantly altered in terms of an ANS imbalance, especially during contract to a stranger, in relation to dysfunctional maternal behavior. Our findings suggest the importance of supporting high quality caregiving that enables the infant to adapt adequately to stressful interpersonal situations which is likely to promote later health.

Changes in heart rate and blood pressure during nocturnal hot flashes associated with and without awakenings

Hot flashes (HFs) are a hallmark of menopause in midlife women. They are beyond bothersome symptoms, having a profound impact on quality of life and wellbeing, and are a potential marker of cardiovascular (CV) disease risk. Here, we investigated the impact on CV functioning of single nocturnal HFs, considering whether or not they were accompanied by arousals or awakenings. We investigated changes in heart rate (HR, 542 HFs), blood pressure (BP, 261 HFs), and pre-ejection period (PEP, 168 HFs) across individual nocturnal physiological HF events in women in the menopausal transition or post-menopause (age: 50.7 ± 3.6 years) (n = 86 for HR, 45 for BP, 27 for PEP). HFs associated with arousals/awakenings (51.1%), were accompanied by an increase in systolic (SBP; ~6 mmHg) and diastolic (DBP; ~5 mmHg) BP and HR (~20% increase), sustained for several minutes. In contrast, HFs occurring in undisturbed sleep (28.6%) were accompanied by a drop in SBP and a marginal increase in HR, likely components of the heat dissipation response. All HFs were accompanied by decreased PEP, suggesting increased cardiac sympathetic activity, with a prolonged increase for HFs associated with sleep disruption. Older age predicted greater likelihood of HF-related sleep disturbance. HFs were less likely to wake a woman in rapid-eye-movement and slow-wave sleep. Findings show that HFs associated with sleep disruption, which are in the majority and more likely in older women, lead to increases in HR and BP, which could have long-term impact on nocturnal CV restoration in women with multiple HFs.

Cardiovascular autonomic dysfunction, altered sleep architecture, and muscle overactivity during nocturnal sleep in pediatric patients with narcolepsy type 1

Study Objectives

Arterial blood pressure (ABP) decreases during sleep compared with wakefulness and this change is blunted in mouse models of and adult patients with narcolepsy type 1 (NT1). We tested whether: (1) pediatric patients with NT1 have similar cardiovascular autonomic abnormalities during nocturnal sleep; and (2) these abnormalities can be linked to hypocretin-1 cerebrospinal fluid concentration (CSF HCRT-1), sleep architecture, or muscle activity.

Methods

Laboratory polysomnographic studies were performed in 27 consecutive drug-naïve NT1 children or adolescents and in 19 matched controls. Nocturnal sleep architecture and submentalis (SM), tibialis anterior (TA), and hand extensor (HE) electromyographic (EMG) activity were analyzed. Cardiovascular autonomic function was assessed through the analysis of pulse transit time (PTT) and heart period (HP).

Results

PTT showed reduced lengthening during total sleep and REM sleep compared with nocturnal wakefulness in NT1 patients than in controls, whereas HP did not. NT1 patients had altered sleep architecture, higher SM EMG during REM sleep, and higher TA and HE EMG during N1–N3 and REM sleep when compared with controls. PTT alterations found in NT1 patients were more severe in subjects with lower CSF HRCT-1, but did not cluster or correlate with sleep architecture alterations or muscle overactivity during sleep.

Conclusion

Our results suggest that pediatric NT1 patients close to disease onset have impaired capability to modulate ABP as a function of nocturnal wake–sleep transitions, possibly as a direct consequence of hypocretin neuron loss. The relevance of this finding for cardiovascular risk later in life remains to be determined.

Automatic analysis of pre-ejection period during sleep using impedance cardiogram

The pre-ejection period (PEP) is a valid index of myocardial contractility and beta-adrenergic sympathetic control of the heart defined as the time between electrical systole (ECG Q wave) to the initial opening of the aortic valve, estimated as the B point on the impedance cardiogram (ICG). B-point detection accuracy can be severely impacted if ICG cardiac cycles corrupted by motion artifact, noise, or electrode displacement are included in the analyses. Here, we developed new algorithms to detect and exclude corrupted ICG cycles by analyzing their level of activity. PEP was then estimated and analyzed on ensemble-averaged clean ICG cycles using an automatic algorithm previously developed by the authors for the detection of B point in awake individuals. We investigated the algorithms' performance relative to expert visual scoring on long-duration data collected from 20 participants during overnight recordings, where the quality of ICG could be highly affected by movement artifacts and electrode displacements and the signal could also vary according to sleep stage and time of night. The artifact rejection algorithm achieved a high accuracy of 87% in detection of expert-identified corrupted ICG cycles, including those with normal amplitude as well as out-of-range values, and was robust to different types and levels of artifact. Intraclass correlations for concurrent validity of the B-point detection algorithm in different sleep stages and in-bed wakefulness exceeded 0.98, indicating excellent agreement with the expert. The algorithms show promise toward sleep applications requiring accurate and reliable automatic measurement of cardiac hemodynamic parameters.

Lower resting cardiac autonomic balance in young adults with current major depression

Research on cardiac autonomic function in major depressive disorder (MDD) has predominantly examined cardiac vagal control and adopted a model of reciprocal autonomic balance. A proposed bivariate autonomic continuum uses cardiac autonomic balance (CAB) and cardiac autonomic regulation (CAR) models, derived from normalized values of respiratory sinus arrhythmia and pre-ejection period, to more adequately index patterns of autonomic control. The purpose of this study was to assess resting levels of CAB and CAR among young adults with and without a current diagnosis of major depression. One hundred forty-two young adults (n = 65 MDD, n = 77 healthy controls; 20.8 ± 2.6 years) completed a structured diagnostic interview, cardiovascular assessment, and a maximal aerobic fitness test. The findings revealed that CAB, but not CAR, significantly predicted current MDD status (OR = 0.70, 95% CI [0.53, 0.93]), an effect that remained after controlling for aerobic fitness and body mass index. Although CAB was found to be a significant predictor of current MDD status among a sample of young adults, there remained substantial variation in autonomic control that was not captured by the traditional model of reciprocal autonomic balance.

Gut permeability and depressive symptom severity in unmedicated adolescents

OBJECTIVE

This study examined gut permeability in unmedicated adolescents with and without major depressive disorder.

METHOD

Medically healthy, non-medicated, 12-17 year-old females in a major depressive episode (MDE) or healthy controls, without any psychiatric condition, were enrolled. They completed the Children's Depression Rating Scale-Revised (CDRS-R) and underwent a clinical interview. Preejection period (PEP) and respiratory sinus arrhythmia (RSA) data were collected to measure autonomic nervous system activity. Following an overnight fast, participants ingested lactulose and mannitol and collected urine for 4 hours while still fasting, to examine gut permeability. Plasma cytokines (interleukin 1β, interleukin 6, and tumor necrosis factor α) were measured. Correlational analyses were used to examine the associations between relevant variables.

RESULTS

41 female participants (age: 14.8 ± 1.6 years, n = 25 with MDE) were enrolled. PEP, but not RSA, was inversely associated with neurovegetative symptom severity on the CDRS-R (r = -0.31, p < 0.06). In the 30 participants with gut permeability data, the lactulose to mannitol ratio (LMR) was significantly positively associated with depression severity, particularly neurovegetative symptom severity (r = 0.37, p < 0.05). Notably, the association between neurovegetative symptom severity and PEP was substantially reduced after adjusting for LMR. Additionally, depression severity was significantly associated with circulating cytokines.

CONCLUSIONS

This is the first study to examine gut permeability in unmedicated adolescents, offering preliminary support for a mechanistic pathway linking sympathetic nervous system activation to increased gut permeability and activation of the innate immune system, likely contributing to the emergence of neurovegetative symptoms of depression.

Should heart rate variability be "corrected" for heart rate? Biological, quantitative, and interpretive considerations

Metrics of heart period variability are widely used in the behavioral and biomedical sciences, although somewhat confusingly labeled as heart rate variability (HRV). Despite their wide use, HRV metrics are usually analyzed and interpreted without reference to prevailing levels of cardiac chronotropic state (i.e., mean heart rate or mean heart period). This isolated treatment of HRV metrics is nontrivial. All HRV metrics routinely used in the literature exhibit a known and positive relationship with the mean duration of the interval between two beats (heart period): as the heart period increases, so does its variability. This raises the question of whether HRV metrics should be "corrected" for the mean heart period (or its inverse, the heart rate). Here, we outline biological, quantitative, and interpretive issues engendered by this question. We provide arguments that HRV is neither uniformly nor simply a surrogate for heart period. We also identify knowledge gaps that remain to be satisfactorily addressed with respect to assumptions underlying existing HRV correction approaches. In doing so, we aim to stimulate further progress toward the rigorous use and disciplined interpretation of HRV. We close with provisional guidance on HRV reporting that acknowledges the complex interplay between the mean and variability of the heart period.