Menstrual Cycle Changes in Vagally-Mediated Heart Rate Variability are Associated with Progesterone: Evidence from Two Within-Person Studies

Publication guidelines for human heart rate and heart rate variability studies in psychophysiology-Part 1: Physiological underpinnings and foundations of measurement

This Committee Report provides methodological, interpretive, and reporting guidance for researchers who use measures of heart rate (HR) and heart rate variability (HRV) in psychophysiological research. We provide brief summaries of best practices in measuring HR and HRV via electrocardiographic and photoplethysmographic signals in laboratory, field (ambulatory), and brain-imaging contexts to address research questions incorporating measures of HR and HRV. The Report emphasizes evidence for the strengths and weaknesses of different recording and derivation methods for measures of HR and HRV. Along with this guidance, the Report reviews what is known about the origin of the heartbeat and its neural control, including factors that produce and influence HRV metrics. The Report concludes with checklists to guide authors in study design and analysis considerations, as well as guidance on the reporting of key methodological details and characteristics of the samples under study. It is expected that rigorous and transparent recording and reporting of HR and HRV measures will strengthen inferences across the many applications of these metrics in psychophysiology. The prior Committee Reports on HR and HRV are several decades old. Since their appearance, technologies for human cardiac and vascular monitoring in laboratory and daily life (i.e., ambulatory) contexts have greatly expanded. This Committee Report was prepared for the Society for Psychophysiological Research to provide updated methodological and interpretive guidance, as well as to summarize best practices for reporting HR and HRV studies in humans.

Associations of luteal phase changes in vagally mediated heart rate variability with premenstrual emotional changes

BACKGROUND

A recent meta-analysis revealed that vagally mediated heart rate variability (vmHRV; a biomarker of emotion regulation capacity) significantly decreases in the luteal phase of the menstrual cycle. As two follow-up studies suggest, these vmHRV decreases are driven primarily by increased luteal progesterone (P4). However, analyses also revealed significant interindividual differences in vmHRV reactivity to the cycle, which is in line with longstanding evidence for interindividual differences in mood sensitivity to the cycle. The present study begins to investigate whether these interindividual differences in vmHRV cyclicity can explain who is at higher risk of showing premenstrual emotional changes. We expected a greater degree of midluteal vmHRV decrease to be predictive of a greater premenstrual increase in negative affect.

METHODS

We conducted an observational study with a naturally cycling community sample (N = 31, M = 26.03 years). Over a span of six weeks, participants completed (a) daily ratings of negative affect and (b) counterbalanced lab visits in their ovulatory, midluteal, and perimenstrual phases. Lab visits were scheduled based on positive ovulation tests and included assessments of baseline vmHRV and salivary ovarian steroid levels.

RESULTS

In line with previous research, multilevel models suggest that most of the sample shows ovulatory-to-midluteal vmHRV decreases which, however, were not associated with premenstrual emotional changes. Interestingly, it was only the subgroup with luteal increases in vmHRV whose negative affect markedly worsened premenstrually and improved postmenstrually.

CONCLUSION

The present study begins to investigate cyclical changes in vmHRV as a potential biomarker of mood sensitivity to the menstrual cycle. The results demonstrate a higher level of complexity in these associations than initially expected, given that only atypical midluteal increases in vmHRV are associated with greater premenstrual negative affect. Potential underlying mechanisms are discussed, among those the possibility that luteal vmHRV increases index compensatory efforts to regulate emotion in those with greater premenstrual negative affect. However, future studies with larger and clinical samples and more granular vmHRV assessments should build on these findings and further explore associations between vmHRV cyclicity and menstrually related mood changes.

Sleep-phasic heart rate variability predicts stress severity: Building a machine learning-based stress prediction model

We propose a novel approach for predicting stress severity by measuring sleep phasic heart rate variability (HRV) using a smart device. This device can potentially be applied for stress self-screening in large populations. Using a Holter electrocardiogram (ECG) and a Huawei smart device, we conducted 24-h dual recordings of 159 medical workers working regular shifts. Based on photoplethysmography (PPG) and accelerometer signals acquired by the Huawei smart device, we sorted episodes of cyclic alternating pattern (CAP; unstable sleep), non-cyclic alternating pattern (NCAP; stable sleep), wakefulness, and rapid eye movement (REM) sleep based on cardiopulmonary coupling (CPC) algorithms. We further calculated the HRV indices during NCAP, CAP and REM sleep episodes using both the Holter ECG and smart-device PPG signals. We later developed a machine learning model to predict stress severity based only on the smart device data obtained from the participants along with a clinical evaluation of emotion and stress conditions. Sleep phasic HRV indices predict individual stress severity with better performance in CAP or REM sleep than in NCAP. Using the smart device data only, the optimal machine learning-based stress prediction model exhibited accuracy of 80.3 %, sensitivity 87.2 %, and 63.9 % for specificity. Sleep phasic heart rate variability can be accurately evaluated using a smart device and subsequently can be used for stress predication.

Menstrual Irregularity: A Physiological Adaptation to Cope Perceived Stress

INTRODUCTION

Menstrual cycle characteristics are regulated hormonally and are integrated at the level of the hypothalamus. Stress can affect the hypothalamic-pituitary gonadal axis. The objective of the study was to analyse the stress levels of women and compare their autonomic tone and menstrual characteristics.

METHODOLOGY

A group of 100 apparently healthy, young, female volunteers were included in this pilot cohort study. Subjects were assessed for perceived stress using the Perceived Stress Scale 14 Item (PSS-14) questionnaire, underwent a heart rate variability (HRV) test on the second, 10th, and 21st days of their menstrual cycle, and their menstrual history was recorded. The statistical analysis was done using Statistical Product and Service Solutions (SPSS, version 21.0; IBM SPSS Statistics for Windows, Armonk, NY) software. Metric data were expressed in terms of numerical value and analysed as mean ± SD. Paired Student's T-test was used to compare the HRV data of all three days of the menstrual cycle separately, and p value<0.05 was considered significant. Menstrual irregularity was complained of by 13 subjects (Group A), and the rest (87 subjects) reported regular menses (Group B).

RESULT

The perceived stress scores of Group A were significantly higher than Group B (32.53±5.062 vs 28.057±7.618; p=0.044). On second day, Group A had higher median R-R interval (714.38±106 vs 656.84±73.50 ms; p=0.015) and lower average heart rate (85.85±12.07 vs 92.39±9.98 bpm; p=0.034) than Group B, suggesting parasympathetic dominance. On the 10th day, Group A had a higher standard deviation of heart rate (7.09±1.88 vs 5.97±1.71 bpm; p=0.032) and a very low-frequency band (1105.94±984.12 vs 730.49±557.41 μs2; p=0.046) than Group B, indicating parasympathetic dominance in Group A. On the 21st day, Group A had a higher standard deviation of R-R interval (58.19±20.46 vs 44.85±14.55 ms; p=0.004), root mean square standard deviation (55.71±29.84 vs 31.89±15.99 ms; p<0.001), percentage of R-R differing by 50 ms (19.20±19.58 vs 10.87±10.31%; p=0.020), total power (3,440.23±2722.29 vs 2,068.28±1,322.49 μs2; p=0.004), high-frequency band (1,247.57±1173.54 vs 539.06±HPO438.92 μs2; p<0.001), standard deviation ratio of the Poincaré plot (0.53±0.19 vs 0.39±0.16; p=0.003), normalised HF (44.0±12.9 vs 35.4±10.6; p=0.009), and a lower LF/HF ratio (1.43±0.80 vs 2.11±1.16; p=0.043) and normalised LF (53.9±14.4 vs 64.1±11.9; p=0.006) than Group B, suggesting higher parasympathetic tone of Group A than Group B.

CONCLUSION

Analysing these results, it can be concluded that, in apparently healthy young women, menstrual irregularity is a physiological adaptation to combat perceived stress and maintain parasympathetic dominance.

Autonomic nervous system and endocrine system response to upper or lower cervical spine mobilization in males with persistent post-concussion symptoms: a proof-of-concept trial

INTRODUCTION

The peripheral stress response, consisting of the autonomic nervous system (ANS) and hypothalamic pituitary adrenal-axis (HPA-axis), functions to maintain homeostasis in response to stressors. Cervical spine manual therapy has been shown to differentially modulate the stress response in healthy populations. No study has investigated whether cervical spine mobilizations can differentially modulate the stress response in individuals with persistent post-concussion symptoms (PPCS), a population characterized by a dysfunctional stress response.

METHODS

A randomized, controlled, parallel design trial was performed to investigate whether upper or lower cervical spine mobilization can differentially modulate components of the stress response in individuals with PPCS. The outcomes were salivary cortisol (sCOR) concentration (primary) and the HRV metric, rMSSD, measured with a smartphone application (secondary). Nineteen males diagnosed with PPCS, aged 19-35, were included. Participants were randomly assigned into either intervention group, upper (n = 10) or lower (n = 9) cervical spine mobilization. Each outcome was collected at different time points, pre- and post-intervention. Statistical analyses were performed using the Friedman's Two-Way ANOVA, Mann-Whitney U test, and Wilcoxon Signed Rank Test.

RESULTS

There was a statistically significant within-group reduction in sCOR concentration 30 minutes following lower cervical spine mobilizations and statistically significant within-group increase in rMSSD 30 minutes following upper cervical spine mobilizations.

CONCLUSION

The results of this trial provide preliminary evidence for cervical spine mobilizations to differentially modulate components of the stress response at specific time points. Understanding the mechanisms of the effect of cervical spine mobilizations on the stress response provides a novel rationale for selecting cervical spine mobilizations to rehabilitate individuals with PPCS.

Asymptomatic Autonomic Dysregulation after Recovery from Mild COVID-19 Infection Revealed by Analysis of Heart Rate Variability Responses to Task Load

(1) Background: The coronavirus disease 2019 (COVID-19) infection is often followed by various complications, which can cause disturbances in daily life after recovery from the infectious state, although etiological mechanisms are not fully elucidated. Previous studies have indicated that autonomic dysregulation is an underlying factor, and it is of interest to clarify whether autonomic dysregulation is also present in the asymptomatic subjects after COVID-19 infection (post-COVID-19) for early detection of post-COVID-19 complications. (2) Methods: In the present study, autonomic activity was assessed using heart rate variability (HRV) analysis in the workers who recovered from mild COVID-19 infection (n = 39). They took a leave of absence for an average of 11.9 days and returned to the original work without complications. HRV was measured after an average of 9.3 days from return. High-frequency (HF) and low-frequency (LF) HRV parameters and heart rate (HR) were recorded during a three-behavioral-state paradigm of approximately 5 min length composed of initial rest, task load, and post-task rest periods and were compared with the data of the workers without the history of COVID-19 infection (normal, n = 38). (3) Results: The HRV and HR scores at the initial rest in the post-COVID-19 subjects showed no difference from those in the control. It is found that the post-COVID-19 subjects exhibited an attenuation of LF/HF increment during the task load and an excessive increase of HF together with a decrease of LF, LF/HF and HR during the post-task rest period in comparison with the initial rest scores. (4) Conclusions: These abnormalities are evaluated as asymptomatic autonomic dysregulation in response to task load, are frequently present after COVID-19 infection, and could be related to the generation of complications.

Autonomic nervous system and endocrine system response to upper and lower cervical spine mobilization in healthy male adults: a randomized crossover trial

BACKGROUND

Cervical spine mobilizations may differentially modulate both components of the stress response, consisting of the autonomic nervous system and hypothalamic pituitary adrenal-axis, depending on whether the target location is the upper or lower cervical spine. To date, no study has investigated this.

METHODS

A randomized, crossover trial investigated the effects of upper versus lower cervical mobilization on both components of the stress response simultaneously. The primary outcome was salivary cortisol (sCOR) concentration. The secondary outcome was heart rate variability measured with a smartphone application. Twenty healthy males, aged 21-35, were included. Participants were randomly assigned to block-AB (upper then lower cervical mobilization, n = 10) or block-BA (lower than upper cervical mobilization, n = 10), separated by a one-week washout period. All interventions were performed in the same room (University clinic) under controlled conditions. Statistical analyses were performed with a Friedman's Two-Way ANOVA and Wilcoxon Signed Rank Test.

RESULTS

Within groups, sCOR concentration reduced thirty-minutes following lower cervical mobilization (p = 0.049). Between groups, sCOR concentration was different at thirty-minutes following the intervention (p = 0.018).

CONCLUSION

There was a statistically significant reduction in sCOR concentration following lower cervical spine mobilization, and between-group difference, 30 min following the intervention. This indicates that mobilizations applied to separate target locations within the cervical spine can differentially modulate the stress response.

Free-living competitive racewalkers and runners with energy availability estimates of <35 kcal·kg fat-free mass-1·day-1 exhibit peak serum progesterone concentrations indicative of ovulatory disturbances: a pilot study

Introduction

The release of luteinising hormone (LH) before ovulation is disrupted during a state of low energy availability (EA). However, it remains unknown whether a threshold EA exists in athletic populations to trigger ovulatory disturbances (anovulation and luteal phase deficiency) as indicated by peak/mid-luteal serum progesterone concentration (Pk-PRG) during the menstrual cycle.

Methods

We assessed EA and Pk-PRG in 15 menstrual cycles to investigate the relationship between EA and Pk-PRG in free-living, competitive (trained-elite) Guatemalan racewalkers (n = 8) and runners (n = 7) [aged: 20 (14-41) years; post-menarche: 5 (2-26) years; height: 1.53 ± 0.09 m; mass: 49 ± 6 kg (41 ± 5 kg fat-free mass "FFM")]. EA was estimated over 7 consecutive days within the follicular phase using food, training, and physical activity diaries. A fasted blood sample was collected during the Pk-PRG period, 6-8 days after the LH peak, but before the final 2 days of each cycle. Serum progesterone concentration was quantified using electrochemiluminescence immunoassay.

Results

Participants that reported an EA of <35 kcal·kg FFM-1·day-1 (n = 7) exhibited ovulatory disturbances (Pk-PRG ≤9.40 ng·mL-1). Athletes with EA ≥36 kcal·kg FFM-1·day-1 (n = 8) recorded "normal"/"potentially fertile" cycles (Pk-PRG >9.40 ng·mL-1), except for a single racewalker with the lowest reported protein intake (1.1 g·kg body mass-1·day-1). EA was positively associated with Pk-PRG [r(9) = 0.79, 95% confidence interval (CI): 0.37-0.94; p = 0.003; 1 - β = 0.99] after excluding participants (n = 4) that likely under-reported/reduced their dietary intake.

Conclusions

The result from the linear regression analysis suggests that an EA ≥ 36 kcal·kg FFM-1·day-1 is required to achieve "normal ovulation." The threshold EA associated with ovulatory disturbances in athletes and non-invasive means of monitoring the ovulatory status warrant further research.

Analyzing physiological signals recorded with a wearable sensor across the menstrual cycle using circular statistics

This study aims to identify the most significant features in physiological signals representing a biphasic pattern in the menstrual cycle using circular statistics which is an appropriate analytic method for the interpretation of data with a periodic nature. The results can be used empirically to determine menstrual phases. A non-uniform pattern was observed in ovulating subjects, with a significant periodicity (p< 0.05) in mean temperature, heart rate (HR), Inter-beat Interval (IBI), mean tonic component of Electrodermal Activity (EDA), and signal magnitude area (SMA) of the EDA phasic component in the frequency domain. In contrast, non-ovulating cycles displayed a more uniform distribution (p> 0.05). There was a significant difference between ovulating and non-ovulating cycles (p< 0.05) in temperature, IBI, and EDA but not in mean HR. Selected features were used in training an Autoregressive Integrated Moving Average (ARIMA) model, using data from at least one cycle of a subject, to predict the behavior of the signal in the last cycle. By iteratively retraining the algorithm on a per-day basis, the mean temperature, HR, IBI and EDA tonic values of the next day were predicted with root mean square error (RMSE) of 0.13 ± 0.07 (C°), 1.31 ± 0.34 (bpm), 0.016 ± 0.005 (s) and 0.17 ± 0.17 (μS), respectively.

Development and Parasympathetic Regulation in Male and Female Adolescents with Autism Spectrum Disorder: A Two-Timepoint Longitudinal Study

Prolonged dysregulation of the autonomic nervous system (ANS) may increase propensity for physical or psychiatric illness. The current study examined differences in respiratory sinus arrhythmia (RSA) regulation in 215 adolescents with or without autism spectrum disorder (ASD) at Time 1 (T1; 10-13 years old) and 1 year later (Time 2; T2). Linear mixed effects models demonstrated lower RSA regulation in ASD, and a small interaction effect, showing blunted change in RSA from T1 to T2. Developmental differences in RSA regulation were particularly notable in females with ASD and those taking psychotropic medications. Results expand previous findings of reduced parasympathetic regulation in ASD by revealing a blunted developmental slope, indicating diagnostic differences may persist or worsen over time, particularly in females.

Heart rate variability between hormone phases of the menstrual and oral contraceptive pill cycles of young women

INTRODUCTION

The interplay between the sympathetic and parasympathetic branches of the autonomic nervous system contribute to adequate hemodynamic responses to stressors, reflected by the variation in intervals between heart beats, known as heart rate variability. The sex hormones estrogen and progesterone have been shown to affect autonomic function. The extent to which autonomic function may vary between different hormone phases of the natural menstrual cycle and how this relationship may differ in women taking oral contraceptives has yet to be fully elucidated.

PURPOSE

To investigate differences in heart rate variability between the early follicular and early luteal phases of the menstrual cycle in naturally menstruating women and in oral contraceptive pill users.

METHODS

Twenty-two young (22 ± 3 years), healthy women who were naturally menstruating or taking oral contraceptive pills participated in this study. Heart rate variability was measured at rest and during two sympathomimetic stressors: isometric handgrip exercise and cold pressor test.

RESULTS

The proportion of successive NN intervals that differ by more than 50 ms was higher in oral contraceptive pill users during the placebo pill phase. Absolute high-frequency power was higher in the naturally menstruating women during the early luteal phase, relative to the early follicular phase. Other indices of vagal modulation were not different at rest or during sympathetic activation between hormone phases or groups.

CONCLUSIONS

Vagal modulation may be increased in the early luteal menstrual cycle phase. Further,oral contraceptive use does not appear to adversely affect this modulation in young, healthy women.

Nocturnal Heart Rate Variability in Women Discordant for Hormonal Contraceptive Use

PURPOSE

The aim of this study was to investigate within-cycle differences in nocturnal heart rate (HR) and heart rate variability (HRV) in naturally menstruating women (NM) and women using combined hormonal contraceptives (CU) or progestin-only hormonal contraceptives (PU).

METHODS

Physically active participants were recruited into three groups: NM ( n = 19), CU ( n = 11), and PU ( n = 12). Participants' HR and HRV (with Bodyguard 2 HRV monitor) and blood hormones were monitored during one menstrual cycle (MC) (NM group) or for 4 wk (CU and PU groups). Estradiol, progesterone, and luteinizing hormone were analyzed from fasting blood samples collected four times in the NM (M1 = bleeding, M2 = follicular phase, M3 = ovulation, and M4 = luteal phase) and PU groups (M1 = lowest E 2 , M2 = M1 + 7 d, M3 = M1 + 14 d, and M4 = M1 + 21 d) and twice in the CU group (active and inactive pill phases). After every blood sample, nightly HR and HRV were recorded and examined as an average from two nights.

RESULTS

Hormonal concentrations differed ( P < 0.05) between MC phases in the NM and PU groups, but not ( P ≥ 0.116) between the active and the inactive phases in the CU group. In the NM and PU groups, some of the HRV values were higher, whereas in the NM group, HR was lower during M2 compared with M3 ( P < 0.049) and M4 ( P < 0.035). In the CU group, HRV values ( P = 0.014-0.038) were higher, and HR was lower ( P = 0.038) in the inactive phase compared with the first week of the active phase.

CONCLUSIONS

The MC and the hormonal cycle phases influence autonomic nervous system balance, which is reflected in measurements of nocturnal HR and HRV. This should be considered when monitoring recovery in physically active individuals.

Periovulatory Subphase of the Menstrual Cycle Is Marked by a Significant Decrease in Heart Rate Variability

(1) Background: High-frequency heart rate variability (HF-HRV) is an essential ultradian rhythm that reflects the activity of the PNS to decelerate the heart. It is unknown how HF-HRV varies across the menstrual cycle (MC), and whether progesterone mediates this potential variation. (2) Methods: We enrolled 33 women in the study to attend eight clinic visits across the MC, during which we measured their resting HF-HRV and collected samples for the analysis of luteinizing hormone (LH) and progesterone. We realigned the study data according to the serum LH surge to the early follicular, mid-follicular, periovulatory, early luteal, mid-luteal and late luteal subphases. (3) Results: Pairwise comparisons between all the subphases showed significant differences between the early follicular and periovulatory subphases (β = 0.9302; p ≤ 0.001) and between the periovulatory and early luteal subphases (β = -0.6955; p ≤ 0.05). Progesterone was positively associated with HF-HRV in the early follicular subphase but not the periovulatory subphase (p ≤ 0.05). (4) Conclusions: The present study shows a significant drop in HF-HRV in the anticipation of ovulation. Further research in this area is critical given the marked cardiovascular disease mortality in women.

Menstrual cycle symptomatology during the COVID-19 pandemic: The role of interoceptive sensibility and psychological health

The literature on the COVID-19 pandemic has shown the importance of investigating its impact on mental health during this sensitive period, also in relation to the female menstrual cycle. To this end, interceptive sensibility has emerged as a fundamental construct for studying the mind-body interaction among psychosomatic and pain symptoms, particularly through the distinction between two attentional styles (namely, a "mindful" and a "non-mindful" sensibility). The aim of the following study is to verify the role of mental health and interoceptive sensibility on menstrual symptoms in women of childbearing age, during the pandemic, as well as to identify the specific contribution of the existing dimensions of interoceptive sensibility in the prediction of symptoms' severity. Data were collected through an online survey, for which 5294 women responded on demographic information, menstrual history, symptoms' disturbance, and completed the Italian versions of the GHQ-12 and the MAIA. The analyses showed that symptoms were strongly correlated to either the GHQ-12 and the MAIA subscales Noticing, Emotional Awareness, Trusting and Not-Worrying. This result was further verified via a hierarchical regression, which revealed that the same interoceptive dimensions and mental health strongly predicted the intensity of menstrual symptoms (R² = 0.177, ΔR² = 0.143) compared to other considered dimensions (R² = 0.180, ΔR² = 0.002). Results are partially in line with the premises but suggest that mental health has a strong impact on the experience of the menstrual cycle and that only a few interoceptive dimensions may be relevant in explaining the severity of menstrual symptoms. It is here suggested that noticing internal bodily signals and being aware of emotional states might become dysfunctional if not reconciled with a good ability to self-regulate internal states, but may rather contribute to the perpetuation of the 'vicious cycle' of heightened affective and attentional reactions to interoceptive sensations.

Face your heart: resting vagally mediated Heart Rate Variability Shapes Social Attributions from facial appearance

Phylogenetic theories suggest resting vagally mediated heart rate variability (vmHRV) as a biomarker for adaptive behavior in social encounters. Until now, no study has examined whether vmHRV can predict individual differences in inferring personality traits and intentions from facial appearance. To test this hypothesis, resting vmHRV was recorded in 83 healthy individuals before they rated a series of faces based on their first impression of trustworthiness, dominance, typicality, familiarity, caring, and attractiveness. We found an association between individual differences in vmHRV and social attributions from facial appearance. Specifically, higher levels of vmHRV predicted higher scores on ratings of caring and trustworthiness, suggesting that strangers’ faces are more likely to be perceived as safer. The present results suggest that higher levels of vmHRV (compared with lower levels of vmHRV) are associated with the tendency to minimize social evaluative threat and maximize affiliative social cues at a first glance of others’ faces.

Using machine learning to estimate the calendar age based on autonomic cardiovascular function

Introduction

Aging is accompanied by physiological changes in cardiovascular regulation that can be evaluated using a variety of metrics. In this study, we employ machine learning on autonomic cardiovascular indices in order to estimate participants' age.

Methods

We analyzed a database including resting state electrocardiogram and continuous blood pressure recordings of healthy volunteers. A total of 884 data sets met the inclusion criteria. Data of 72 other participants with an BMI indicating obesity (>30 kg/m²) were withheld as an evaluation sample. For all participants, 29 different cardiovascular indices were calculated including heart rate variability, blood pressure variability, baroreflex function, pulse wave dynamics, and QT interval characteristics. Based on cardiovascular indices, sex and device, four different approaches were applied in order to estimate the calendar age of healthy subjects, i.e., relevance vector regression (RVR), Gaussian process regression (GPR), support vector regression (SVR), and linear regression (LR). To estimate age in the obese group, we drew normal-weight controls from the large sample to build a training set and a validation set that had an age distribution similar to the obesity test sample.

Results

In a five-fold cross validation scheme, we found the GPR model to be suited best to estimate calendar age, with a correlation of r=0.81 and a mean absolute error of MAE=5.6 years. In men, the error (MAE=5.4 years) seemed to be lower than that in women (MAE=6.0 years). In comparison to normal-weight subjects, GPR and SVR significantly overestimated the age of obese participants compared with controls. The highest age gap indicated advanced cardiovascular aging by 5.7 years in obese participants.

Discussion

In conclusion, machine learning can be used to estimate age on cardiovascular function in a healthy population when considering previous models of biological aging. The estimated age might serve as a comprehensive and readily interpretable marker of cardiovascular function. Whether it is a useful risk predictor should be investigated in future studies.

Pilot examination of stress, heart rate variability, and alcohol craving and use among female veterans

Rates of alcohol use disorder (AUD) are increasing among civilian and veteran populations of women in the United States, and stress pathophysiology (i.e., abnormal acute and long-term change in physiological responses to stress) is central to the maintenance of alcohol misuse within this population. Heart rate variability (HRV) is one measure of stress regulation that may help to explain the association of stress with alcohol misuse among women. In the current analysis of pilot data, 20 women veterans attended an in-person laboratory session and completed 35 daily assessments of their alcohol use and craving. During the lab session, the effects of a stress induction procedure on self-reported alcohol craving and HRV were assessed. HRV was continuously measured and indexed in the time domain, using the root mean square of successive differences between normal heartbeats (RMSSD). Alcohol craving and use during the longitudinal 35-day study period were measured via self-report questionnaires sent to participants' phones. Results indicated that resting HRV in the lab was positively associated with odds of daily craving. Moreover, HRV during the stressor, as measured in lab, was positively associated with (1) overall alcohol craving in the lab (i.e., with resting and post-stress craving), and (2) number of daily drinks during the 35-day study period. This pilot study suggests the potential role of HRV in response to stressors in predicting alcohol craving and use among female veterans. It provides pilot data for research on stress-reactive HRV as a biomarker for alcohol misuse among women, and discusses directions for future research.

Birth, love, and fear: Physiological networks from pregnancy to parenthood

Pregnancy and childbirth are among the most dramatic physiological and emotional transformations of a lifetime. Despite their central importance to human survival, many gaps remain in our understanding of the temporal progression of and mechanisms underlying the transition to new parenthood. The goal of this paper is to outline the physiological and emotional development of the maternal-infant dyad from late pregnancy to the postpartum period, and to provide a framework to investigate this development using non-invasive timeseries. We focus on the interaction among neuroendocrine, emotional, and autonomic outputs in the context of late pregnancy, parturition, and post-partum. We then propose that coupled dynamics in these outputs can be leveraged to map both physiologic and pathologic pregnancy, parturition, and parenthood. This approach could address gaps in our knowledge and enable early detection or prediction of problems, with both personalized depth and broad population scale.

Longitudinally Tracking Maternal Autonomic Modulation During Normal Pregnancy With Comprehensive Heart Rate Variability Analyses

Changes in the maternal autonomic nervous system are essential in facilitating the physiological changes that pregnancy necessitates. Insufficient autonomic adaptation is linked to complications such as hypertensive diseases of pregnancy. Consequently, tracking autonomic modulation during progressing pregnancy could allow for the early detection of emerging deteriorations in maternal health. Autonomic modulation can be longitudinally and unobtrusively monitored by assessing heart rate variability (HRV). Yet, changes in maternal HRV (mHRV) throughout pregnancy remain poorly understood. In previous studies, mHRV is typically assessed only once per trimester with standard HRV features. However, since gestational changes are complex and dynamic, assessing mHRV comprehensively and more frequently may better showcase the changing autonomic modulation over pregnancy. Subsequently, we longitudinally (median sessions = 8) assess mHRV in 29 healthy pregnancies with features that assess sympathetic and parasympathetic activity, as well as heart rate (HR) complexity, HR responsiveness and HR fragmentation. We find that vagal activity, HR complexity, HR responsiveness, and HR fragmentation significantly decrease. Their associated effect sizes are small, suggesting that the increasing demands of advancing gestation are well tolerated. Furthermore, we find a notable change in autonomic activity during the transition from the second to third trimester, highlighting the dynamic nature of changes in pregnancy. Lastly, while we saw the expected rise in mean HR with gestational age, we also observed increased autonomic deceleration activity, seemingly to counter this rising mean HR. These results are an important step towards gaining insights into gestational physiology as well as tracking maternal health via mHRV.

Heart rate variability as a function of menopausal status, menstrual cycle phase, and estradiol level

Low estradiol status is associated with increased cardiovascular risk. We sought to determine the association between heart rate variability (HRV), a marker of cardiovascular risk, at baseline and in response to stressor as a function of menopausal status, menstrual cycle phase and estradiol level. Forty-one healthy women (13 postmenopausal, 28 premenopausal) were studied. Eleven premenopausal women were additionally studied in the high and low estradiol phases of the menstrual cycle. HRV was calculated by spectral power analysis (low Frequency (LF), high frequency (HF) and LF:HF) at baseline and in response to graded Angiotensin II (AngII) infusion. The primary outcomes were differences in HRV at baseline and in response to AngII. Compared to premenopausal women in the low estradiol phase, postmenopausal women demonstrated lower baseline LF (p = 0.01) and HF (p < 0.001) measures, which were not significant after adjustment for age and BMI. In response to AngII, a decrease in cardioprotective HRV (ΔHF = -0.43 ± 0.46 ln ms² , p = 0.005 vs. baseline) was observed in postmenopausal women versus premenopausal women. Baseline HRV parameters did not differ by menstrual phase in premenopausal women. During the low estradiol phase, no differences were observed in the HRV response to AngII challenge. In contrast, women in the high estradiol phase were unable to maintain HRV (ΔLF = -0.07 ± 0.46 ln ms² , p = 0.048 response vs. baseline, ΔHF = -0.33 ± 0.74 ln ms2, p = 0.048 response vs. baseline). No association was observed between any measure of HRV and estradiol level. Menopausal status and the high estradiol phase in premenopausal women were associated with reduced HRV, a marker of cardiovascular risk. Understanding the role of estradiol in the modulation of cardiac autonomic tone may help guide risk reduction strategies in women.

Tracking Sleep, Temperature, Heart Rate, and Daily Symptoms Across the Menstrual Cycle with the Oura Ring in Healthy Women

Background and Objective

The ovulatory menstrual cycle is characterized by hormonal fluctuations that influence physiological systems and functioning. Multi-sensor wearable devices can be sensitive tools capturing cycle-related physiological features pertinent to women’s health research. This study used the Oura ring to track changes in sleep and related physiological features, and also tracked self-reported daily functioning and symptoms across the regular, healthy menstrual cycle.

Methods

Twenty-six healthy women (age, mean (SD): 24.4 (1.1 years)) with regular, ovulatory cycles (length, mean (SD): 28.57 (3.8 days)) were monitored across a complete menstrual cycle. Four menstrual cycle phases, reflecting different hormone milieus, were selected for analysis: menses, ovulation, mid-luteal, and late-luteal. Objective measures of sleep, sleep distal skin temperature, heart rate (HR) and vagal-mediated heart rate variability (HRV, rMSSD), derived from the Oura ring, and subjective daily diary measures (eg sleep quality, readiness) were compared across phases.

Results

Wearable-based measures of sleep continuity and sleep stages did not vary across the menstrual cycle. Women reported no menstrual cycle-related changes in perceived sleep quality or readiness and only marginally poorer mood in the midluteal phase. However, they reported moderately more physical symptoms during menses (p < 0.001). Distal skin temperature and HR, measured during sleep, showed a biphasic pattern across the menstrual cycle, with increased HR (p < 0.03) and body temperature (p < 0.001) in the mid- and late-luteal phases relative to menses and ovulation. Correspondingly, rMSSD HRV tended to be lower in the luteal phase. Further, distal skin temperature was lower during ovulation relative to menses (p = 0.05).

Conclusion

The menstrual cycle was not accompanied by significant fluctuations in objective and perceived measures of sleep or in mood, in healthy women with regular, ovulatory menstrual cycles. However, other physiological changes in skin temperature and HR were evident and may be longitudinally tracked with the Oura ring in women over multiple cycles in a natural setting.

Comparison of Heart Rate Variability, QTc, and JT Interval Between Diabetic Patients and Healthy Controls: Role of Gender and Phases of Menstrual Cycle

Background and objectives

Type 2 Diabetes mellitus (T2DM) is a heterogeneous group of metabolic disorders with variable degrees of insulin resistance and altered glucose metabolism. Increased attention in studying the role of gonadal hormones in diabetes is not only due to their relation to insulin sensitivity, and glucose tolerance but also to the gender-specific nature of the prevalence of various diabetic complications. The cyclical change in the hormone level in females will make it necessary to consider the menstrual cycle while analyzing the risk factors for diabetes. Hence, the role of gender and menstrual cycle in T2DM are analyzed here using the simple non-invasive cardiovascular risk indices like heart rate variability (HRV), QT interval corrected for heart rate (QTc), and JT interval.

Materials and methods

In this analytical study, T2DM patients in the age group of 18-45 years with less than five years duration from diagnosis and taking not more than two anti-hyperglycemic drugs were included. Time and frequency domains of HRV analysis, QTc, and JT intervals were compared with age and BMI matched control group. The comparison of these parameters was also made between two genders in the diabetic group and they were analyzed across different phases of the menstrual cycle in female diabetic patients when physiological variation in the gonadal hormones occurred as a natural phenomenon.

Results

HRV parameters were reduced and the QTc and JT intervals were prolonged in diabetic patients of both genders. Reduction in low-frequency (LF) band power and high-frequency (HF) band power of HRV analysis in diabetic females were statistically significant in the luteal phase of the menstrual cycle in comparison with age and BMI-matched healthy controls. There was no significant difference in the HRV parameters, QTc, and JT interval between the male and female diabetic groups. HF band power is significantly reduced in the menstrual phase and relatively higher in the follicular phase when compared to the luteal phase among female diabetic patients.

Conclusion

The reduced sympathetic and parasympathetic activity were observed in diabetic patients of both genders and they were significant in the luteal phase of diabetic females compared to the healthy control group. Vagal activity is relatively higher in the follicular phase of the menstrual cycle in female diabetic patients.

Autonomic dysfunction in adults following mild traumatic brain injury: A systematic review

BACKGROUND

Increasing evidence suggests autonomic nervous system (ANS) dysfunction may occur following mild traumatic brain injury (mTBI). Measures of heart rate, heart rate variability, blood pressure and baroreceptor sensitivity can be used to evaluate ANS dysfunction following mTBI.

OBJECTIVE

Summarize the evidence for ANS dysfunction in adults following mTBI.

METHODS

A search of Embase, MEDLINE, Cochrane Central Register, PsycINFO, CINAHL and SPORTDiscus databases was conducted. Search topics included: mTBI and ANS. Identified abstracts were independently reviewed by 2 reviewers followed by full text screening. Risk of bias was assessed using a modified SIGN checklist. A structured synthesis was performed.

RESULTS

Thirty-nine studies (combined 1,467 participants diagnosed with mTBI) evaluating ANS function were included. ANS function was evaluated under various conditions including: rest, during exertion, cold pressor test, Valsalva maneuver, using face cooling and eyeball pressure paradigms. Short-term or ultra-short-term recordings were most common. The majority of studies (28/39) were rated as "unacceptable" for quality of evidence.

CONCLUSIONS

Altered parameters of ANS function have been reported in multiple conditions following mTBI, both acutely and in the post-acute/chronic stages of recovery. However, due to methodological limitations, conclusions regarding the severity and timing of ANS dysfunction following mTBI cannot be drawn.

Competitive dynamics underlie cognitive improvements during sleep

Sleep facilitates both long-term episodic memory consolidation and short-term working memory functioning. However, the mechanism by which the sleeping brain performs both complex feats and which sleep features are associated with these processes remain unclear. Using a pharmacological approach, we demonstrate that long-term and working memory are served by distinct offline neural mechanisms and that these mechanisms are mutually antagonistic. We propose a sleep switch model in which the brain toggles between the two memory processes via a complex interaction at the synaptic, systems, and mechanistic level with implications for research on cognitive disturbances observed in neurodegenerative disorders such as Alzheimer’s and Parkinson's disease, both of which involve the decline of sleep.

We provide evidence that human sleep is a competitive arena in which cognitive domains vie for limited resources. Using pharmacology and effective connectivity analysis, we demonstrate that long-term memory and working memory are served by distinct offline neural mechanisms that are mutually antagonistic. Specifically, we administered zolpidem to increase central sigma activity and demonstrated targeted suppression of autonomic vagal activity. With effective connectivity, we determined the central activity has greater causal influence over autonomic activity, and the magnitude of this influence during sleep produced a behavioral trade-off between offline long-term and working memory processing. These findings suggest a sleep switch mechanism that toggles between central sigma-dependent long-term memory and autonomic vagal-dependent working memory processing.

Regulating interpersonal stress: the link between heart-rate variability, physical exercise and social perspective taking under stress

Social interactions can be stressful, especially if they involve provocation or ambiguity. At the same time, such interactions necessitate social cognition. The question thus arises how stress affects social cognition and how personality attributes modulate this effect. The aim of the current study was to investigate the link between emotional reactivity, physical exercise, and social cognition under stress. As a measure of social cognition, we used spontaneous perspective taking, i.e., the degree to which participants represented the mental state of another agent. Studying young female participants, we investigated how physiological regulation, measured through resting heart-rate variability, is related to spontaneous social perspective taking under stress, and to predicted anger in an ambiguous social scenario. When controlling for resting heart rate, vagally mediated heart-rate variability was negatively correlated with the effect of stress on perspective taking, indicating that good physiological regulation supports social cognition under stress. Further, participants who reported to exercise at least once a week showed higher perspective taking under stress than less active participants. Finally, we found tentative evidence for participants who exercised regularly to show reduced predicted anger in response to an ambiguous provocation. Our findings suggest that good physiological regulation and regular physical exercise support social cognition under stress.

Moderation of the Stressor-Strain Process in Interns by Heart Rate Variability Measured with a Wearable and Smartphone App: a Within-Subject Design Using Continuous Monitoring

Background

The emergence of smartphones and wearable sensor technologies enables easy and unobtrusive monitoring of physiological and psychological data related to an individual’s resilience. Heart rate variability (HRV) is a promising biomarker for resilience based on between-subject population studies, but observational studies that apply a within-subject design and use wearable sensors in order to observe HRV in a naturalistic real-life context are needed.

Objective

This study aims to explore whether resting HRV and total sleep time (TST) are indicative and predictive of the within-day accumulation of the negative consequences of stress and mental exhaustion. The tested hypotheses are that demands are positively associated with stress and resting HRV buffers against this association, stress is positively associated with mental exhaustion and resting HRV buffers against this association, stress negatively impacts subsequent-night TST, and previous-evening mental exhaustion negatively impacts resting HRV, while previous-night TST buffers against this association.

Methods

In total, 26 interns used consumer-available wearables (Fitbit Charge 2 and Polar H7), a consumer-available smartphone app (Elite HRV), and an ecological momentary assessment smartphone app to collect resilience-related data on resting HRV, TST, and perceived demands, stress, and mental exhaustion on a daily basis for 15 weeks.

Results

Multiple linear regression analysis of within-subject standardized data collected on 2379 unique person-days showed that having a high resting HRV buffered against the positive association between demands and stress (hypothesis 1) and between stress and mental exhaustion (hypothesis 2). Stress did not affect TST (hypothesis 3). Finally, mental exhaustion negatively predicted resting HRV in the subsequent morning but TST did not buffer against this (hypothesis 4).

Conclusions

To our knowledge, this study provides first evidence that having a low within-subject resting HRV may be both indicative and predictive of the short-term accumulation of the negative effects of stress and mental exhaustion, potentially forming a negative feedback loop. If these findings can be replicated and expanded upon in future studies, they may contribute to the development of automated resilience interventions that monitor daily resting HRV and aim to provide users with an early warning signal when a negative feedback loop forms, to prevent the negative impact of stress on long-term health outcomes.

How to study the menstrual cycle: Practical tools and recommendations

Despite decades of research on the physiological and psychological effects of the menstrual cycle, studies have not sufficiently adopted consistent methods for operationalizing the menstrual cycle. This has resulted in substantial confusion in the literature and limited possibilities to conduct systematic reviews and meta-analyses. In order to facilitate more rapid accumulation of knowledge on cycle effects, the present paper offers a set of integrative guidelines and standardized tools for studying the menstrual cycle as an independent variable. We begin with (1) an overview of the menstrual cycle and (2) premenstrual disorders, followed by (3) recommendations and tools regarding data collection in cycle studies. These recommendations address selecting the appropriate study design and sampling strategy, managing demand characteristics, identifying a sample of naturally-cycling individuals, and measuring menstrual bleeding dates, ovarian hormones, and ovulation. We proceed with suggestions for (4) data preparation and coding of cycle day and phases, as well as (5) data visualization, statistical modeling, and interpretation of menstrual cycle associations. We also provide (6) recommendations for using menses start day and ovulation testing to schedule visits in laboratory studies and end with a (7) comprehensive summary and conclusion. Regardless of whether the influence of the menstrual cycle is of central interest in a study or should be controlled to accurately assess the effects of another variable, the use of these recommendations and tools will help make study results more meaningful and replicable.

The autonomic correlates of dysphoric rumination and post-rumination savoring

Trait dysphoric rumination is a transdiagnostic factor associated with depression and anxiety that has also been linked with blunted respiratory sinus arrhythmia (RSA), an index of reduced emotion regulation capacity. However, the autonomic correlates of state dysphoric rumination remain unclear. We examined the physiological correlates of state dysphoric rumination and the potential repairing effects of savoring on autonomic functioning. To provide a comprehensive assessment of autonomic correlates, we examined changes in parasympathetic (RSA) and sympathetic (cardiac pre-ejection period, PEP; and electrodermal activity, EDA) arousal independently, as well as autonomic coordination among indices. Eighty-two women (ages 18-25) completed laboratory physiological assessments, including rumination and savoring tasks, and self-report measures of trait rumination. Dysphoric rumination was associated with sympathetic activation (i.e., decreases in PEP, increases in EDA), and subsequent savoring following a recovery period also corresponded with decreases in PEP. Trait rumination did not predict autonomic changes during state rumination. However, higher trait rumination was associated with greater sympathetic coordination (PEP-EDA correspondence) during savoring. In summary, dysphoric rumination co-occurred with sympathetic activation, and subsequent savoring successfully recruited sympathetic activity (PEP) redirected on positive moods and events. Results also emphasize the utility of examining sympathetic and parasympathetic indices, and coordination among autonomic indices to delineate autonomic activity associated with emotion regulation strategies.