The predictive value of low heart rate and heart rate variability during stress for reoffending in delinquent male adolescents

Low autonomic (re)activity is a consistent correlate of antisocial behavior in juveniles. However, longitudinal research relating autonomic measures to persistent antisocial behavior has remained scarce. Therefore, in the present study we examined the predictive value of heart rate (HR) and heart rate variability (HRV, often studied as respiratory sinus arrhythmia) for reoffending in delinquent male adolescents. At initial assessment, HR and HRV were measured at rest and in response to a public speaking task. Registered reoffending was assessed after 5-year follow-up. Attenuated HR response and stronger HRV response to stress predicted higher reoffending rates. Results provide evidence that HR/HRV reactivity are neurobiological markers for persistent juvenile antisocial behavior. Although effect sizes were small to moderate, our findings underscore the consistency of the relationship between autonomic markers and antisocial behavior.     

Heart rate variability and pain: associations of two interrelated homeostatic processes

Between-person variability in pain sensitivity remains poorly understood. Given a conceptualization of pain as a homeostatic emotion, we hypothesized inverse associations between measures of resting heart rate variability (HRV), an index of autonomic regulation of heart rate that has been linked to emotionality, and sensitivity to subsequently administered thermal pain. Resting electrocardiography was collected, and frequency-domain measures of HRV were derived through spectral analysis. Fifty-nine right-handed participants provided ratings of pain intensity and unpleasantness following exposure to 4 degrees C thermal pain stimulation, and indicated their thresholds for barely noticeable and moderate pain during three exposures to decreasing temperature. Greater low-frequency HRV was associated with lower ratings of 4 degrees C pain unpleasantness and higher thresholds for barely noticeable and moderate pain. High-frequency HRV was unrelated to measures of pain sensitivity. Findings suggest pain sensitivity is influenced by characteristics of a central homeostatic system also involved in emotion.     

Non-contact monitoring of heart rate variability using medical radar for the evaluation of dynamic changes in autonomic nervous activity during a head-up tilt test

Abstract

Electrocardiography (ECG) is a mandatory standard for monitoring electrical activity of the heart in many clinical settings such as intensive care and emergency units. However, in situations wherein the skin is damaged, such as acute burn injuries, it is impossible to efficiently attach electrodes to the skin. In this study, we developed a non-contact cardiac monitoring system using a 24-GHz medical radar for directly measuring the beat-to-beat heart mechanical activity at a distance from a subject. The heart rate variability (HRV) was analysed using an autoregressive model (AR) from the measured beat-to-beat intervals during a head-up tilt test. To investigate the feasibility of the proposed system, we compared medical radar and ECG recording by using Lin’s correlation coefficient and Bland–Altman analysis, which showed a negligible mean difference from the substantial agreement of Lin’s correlation coefficient of 0.9 between the radar and ECG. The non-contact radar clearly monitored dynamic changes in HRV indices induced by the head-up tilt test. This type of non-contact HRV-sensing technique as an alternative approach has significant potential for advancing personal healthcare in both clinical and out-of-hospital settings.     

AKAP10 (I646V) functional polymorphism predicts heart rate and heart rate variability in apparently healthy, middle-aged European-Americans

Previous evidence suggests that the dual-specific A kinase-anchoring protein 2 functional polymorphism (AKAP10 (A/G) I646V) influences heart rate (HR) and heart rate variability (HRV) in mice and humans ( N =122) with cardiovascular disease. Here, we asked whether this AKAP10 variant predicts HR and HRV in a large sample of healthy humans. Resting HR and short-term time and frequency domain measures of HRV (5 min during paced and unpaced respiration conditions) were assessed in a U.S. community sample ( N =1,033) of generally healthy men and women (age 30–54) of European ancestry. Each person was genotyped for the AKAP10 variant. As with previous work, the AKAP10 Val allele predicted greater resting HR (Paced p <.01; Unpaced p <.03) and diminished HRV (Paced p s <.05) suggesting that this variant may modulate the sensitivity of cardiac pacemaker cells to autonomic inputs, possibly conferring risk for arrhythmias and sudden cardiac death.     

Cortical thickness,resting state heart rate,and heart rate variability in female adolescents

Resting state heart rate variability (HRV) is a psychophysiological marker that has gained increasing research interest, in particular in developmental neuroscience. HRV has been shown to be associated with mental and physical health, beyond simple measures of heart rate (HR) and shows inter‐ and intraindividual variance across aging. Recently, three studies reported on a positive correlation between resting state HRV and cortical thickness in selected regions of interest (ROIs) in adult samples. Structural thickness, HRV, and HR change during the sensitive period of adolescence. Previously, no study has addressed the structural concomitants of resting HR and HRV in adolescents. Cortical thickness (3‐T MRI), HR, and HRV were recorded in 20 healthy, female adolescents (mean age: 15.92 years; SD = 1.06; range: 14–17). In line with existing research in adults, cortical thickness in a number of ROIs was associated with resting state HRV but not HR. The comparison of regression analyses using the Bayes factor revealed evidence for a correlation between HRV and cortical thickness of the bilateral rostral anterior cingulate cortex. However, unlike in adults, greater cortical thickness was associated with reduced HRV in female adolescents. Analyses on HR showed no superior model fit. Results suggest that greater HRV might be beneficial for cortical development during adolescence (cortical thinning). On the other hand, cortical development might determine changes in autonomic nervous system function in adolescents. Future studies are needed to replicate these findings in larger samples including boys and to test these hypotheses in longitudinal designs.     

Equine behaviour and heart rate in temperament tests with or without rider or handler

The aim of the present study was to compare horses' heart rate (HR), heart rate variability (RMSSD, pNN50) and behaviour in the same temperament test when being ridden, led, and released free. Behavioural measurements included scores and linear measurements for reactivity (R), activity (A), time to calm down (T) and emotionality (E), recorded during the approach (1) and/or during confrontation with the stimulus (2). Sixty-five horses were each confronted 3 times (1 ridden, 1 led, 1 free running in balanced order) with 3 novel and/or sudden stimuli. Mixed model analysis indicated that leading resulted in the lowest (P < 0.05 throughout) reactions as measured by A1, A2, E1, E2, R2, and pNN50 while riding produced the strongest (A1, T2, HR, RMSSD, pNN50) or medium (E1, E2, R2) reactions. Free running resulted either in the strongest (A2, E1, E2, R2) or in the lowest (A1, T2, HR, RMSSD, pNN50) reactions. The repeatability across tests for HR (0.57), but not for RMSSD (0.23) or pNN50 (0.25) was higher than for any behavioural measurement: the latter ranged from values below 0.10 (A1, A2, T2) to values between 0.30 and 0.45 (E1, E2, R2). Overall, the results show that a rider or handler influences, but not completely masks, the horses' intrinsic behaviour in a temperament test, and this influence appeared to be stronger on behavioural variables and heart rate variability than on the horses' heart rates. Taking both practical considerations and repeatabilities into account, reactivity appears to be the most valuable parameter. Emotionality and heart rate can also yield valid results reflecting additional dimensions of temperament although their practical relevance may be less obvious. If a combination of observed variables is chosen with care, a valid assessment of a horse's temperament may be possible in all types of tests. However, in practice, tests that resemble the practical circumstances most closely, i.e. testing riding horses under a rider, should be chosen.     

Dietary sodium effects on heart rate variability in salt sensitivity of blood pressure

High dietary sodium intake is a risk factor for hypertension, and heart rate variability (HRV) is decreased in hypertension. Effects of dietary sodium intake on HRV of normotensive persons have not, however, been investigated to date. The present study examined effects of low and high sodium diets on blood pressure, heart rate, and HRV in 36 healthy, normotensive women, ages 40-70. Each was placed on a low sodium diet for 6 days followed by a high sodium diet for 6 days. The high salt diet increased mean systolic blood pressure, decreased heart rate, and increased high frequency HRV (HF). Cardiac vagal tone, estimated at baseline from heart period and a time domain estimate of respiratory sinus arrhythmia, was higher in salt-sensitive than salt-insensitive subjects. The finding of increased vagal tone in normotensive persons on high salt intake indicates that dietary sodium status should be considered in behavioral studies of HRV.     

Effect of low-dose endurance training on heart rate variability at rest and during an incremental maximal exercise test

We evaluated the effects of low-dose endurance training on autonomic HR control. We assessed the heart rate variability (HRV) of 11 untrained male subjects (36.8 +/- 7.2 years) at rest and during an incremental maximal aerobic exercise test prior to a 7-week preparatory period and prior to and following a 14-week endurance training period, including a low to high intensity exercise session twice a week. Total (0.04-1.2 Hz), low (0.04-0.15 Hz) and high (0.15-1.2 Hz) frequency power of HRV were computed by short-time Fourier transform. The preparatory period induced no change in aerobic power or HRV. The endurance training period increased peak aerobic power by 12% (P < 0.001), decreased the HR (P < 0.01) and increased all HRV indices (P < 0.05-0.01) at absolute submaximal exercise intensities, but not at rest. In conclusion, low-dose endurance training enhanced vagal control during exercise, but did not alter resting vagal HR control.     

Visual discrimination learning in dwarf goats and associated changes in heart rate and heart rate variability

We studied visual discrimination learning in a group of Nigerian dwarf goats using a computer-based learning device which was integrated in the animals' home pen. We conducted three consecutive learning tasks (T1, T2 and T3), each of which lasted for 13 days. In each task, a different set of four visual stimuli was presented on a computer screen in a four-choice design. Predefined sequences of stimulus combinations were presented in a pseudorandom order. Animals were rewarded with drinking water when they chose the positive stimulus by pressing a button next to it. Noninvasive measurements of goats' heartbeat intervals were carried out on the first and the last 2 days of each learning task. We analysed heart rate (HR) and heart rate variability (HRV) of resting animals to study sustained physiological effects related to general learning challenge rather than acute excitement during an actual learning session. The number of trials to reach the learning criterion was 1000 in T1, when visual stimuli were presented to the goats for the first time, but decreased to 210 in T2 and 240 in T3, respectively. A stable plateau of correct choices between 70% and 80% was reached on Day 10 in T1, on Day 8 in T2 and on Day 6 in T3. We found a significant influence of the task and of the interaction between task and day on learning success. Whereas HR increased throughout T1, this relationship was inverted in T2 and T3, indicating different effects on the HR depending on how familiar goats were with the learning task. We found a significant influence of the task and the interaction between task and time within the task on HRV parameters, indicating changes of vagal activity at the heart. The results suggest that changes in HR related to learning were predominantly caused by a withdrawal of vagal activity at the heart. With regard to nonlinear processes in heartbeat regulation, increased deterministic shares of HRV indicated that the animals did not really relax until the end of T3. Comparing changes of HR and HRV in T3 and in a subsequent postexperiment (PE), we assume a positive effect of such cognitive challenges once the task had been learned by the animals.     

Circadian rhythm changes in heart rate variability during chronic sound stress

To study the circadian rhythm changes of the heart rate variability (HRV) during chronic sound stress, Wistar rats were implanted with telemetry transmitters and exposed to chronic ultrasound stress for 14 days. The heart rate, mean R-R intervals (mean R-R) and body temperature were monitored hourly. The spectra of five-minute heart rate variability were plotted on a log-log scale of frequency versus power spectral density, and the spectral exponent β of the regression line of this plot was calculated. The exponent β, heart rate (HR) and body temperature recorded hourly were plotted and fitted to sine curves to observe the circadian rhythm of these parameters. The correlation coefficient of the fitted sine curves in β decreased from 0.644 in the control period to 0.105 in the stress period, indicating that the rhythm of β deceased during stress. This did not occur in the other two parameters, demonstrating that the HRV exponent can assess chronic stress.     

Genetic influences on heart rate variability at rest and during stress

We tested whether the heritability of heart rate variability (HRV) under stress is different from rest and its dependency on ethnicity or gender. HRV indexed by root mean square of successive differences (RMSSD) and high-frequency (HF) power was measured at rest and during 3 stressors in 427 European and 308 African American twins. No ethnic or gender differences were found for any measures. There was a nonsignificant increase in heritability of RMSSD (from 0.48 to 0.58) and HF (from 0.50 to 0.58) under stress. Up to 81% and 60% of the heritabilities of RMSSD and HF under stress could be attributed to genes influencing rest levels. The heritabilities due to genes expressed under stress were 0.11 for RMSSD and 0.23 for HF. The findings suggest that, independent of ethnicity and gender, HRV regulation at rest and under stress is largely influenced by the same genes with a small but significant contribution of stress-specific genetic effects.     

The effect of eccentric strength training on heart rate and on its variability during isometric exercise in healthy older men

The purpose of this study was to investigate if chronic eccentric strength training (ST) affects heart rate (HR) and heart rate variability (HRV) during sub-maximal isometric voluntary contractions (SIVC). The training group (TG) (9 men, 62 ± 2) was submitted to ST (12 weeks, 2 days/week, 2–4 sets of 8–12 repetitions at 75–80% peak torque (PT). The control group (CG) (8 men, 64 ± 4) did not perform ST. The HR and the HRV (RMSSD index) were evaluated during SIVC of the knee extension (15, 30 and 40% of PT). ST increased the eccentric torque only in TG, but did not change the isometric PT and the duration of SIVC. During SIVC, the HR response pattern and the RMSSD index were similar for both groups in pre- and post-training evaluations. Although ST increased the eccentric torque in the TG, it did not generate changes in HR or HRV.     

Familiality of heart rate and cardiac-related autonomic activity in five-month-old twins: the Québec newborn twins study

The familiality of infant sleeping heart rate (HR) and cardiac-related autonomic activity, as indexed by spectral analysis of HR variability (HRV) and response to postural change, was investigated in 322 5-month-old twin pairs. The postural change elicited only minor changes in cardiovascular activity. As a result, analyses focused on supine cardiovascular activity. Multivariate genetic modeling indicated that individual differences in sleeping HR and high frequency (HF) HRV were determined by unique environmental and distinct additive genetic factors. These variables, along with low frequency (LF) HRV, were also affected by overlapping familial environmental influences. Familial influences in HF HRV were more pronounced for baby girls than boys. Estimates of relative LF and HF HRV were determined by common (familial) and unique environmental factors; familial influences on these estimates did not overlap with familial influences on sleeping HR.     

Hemodynamic responses and linear and non-linear dynamics of cardiovascular autonomic regulation following supramaximal exercise

The purpose of this study was to examine hemodynamic responses and cardiovascular autonomic regulation following supramaximal exercise. Electrocardiographic R–R intervals and beat-to-beat hemodynamics were recorded before and for 10 min after a 30-s Wingate test in 11 males. Spectral analysis of heart rate (HR) and arterial pressure variability, analysis of HR complexity, the sequence technique and the cross-spectral transfer function were used to quantify autonomic regulation and baroreflex sensitivity. After exercise, the high frequency component of HR variability (vagal-related index) was lower than pre-exercise values, whereas the ratio low frequency to high frequency (index of sympathovagal balance) and the low frequency component of blood pressure variability (index of sympathetic vasomotor tone) were greater than baseline (p < 0.05). Post-exercise HR complexity and baroreflex sensitivity were reduced compared to baseline, p < 0.05. Cardiovascular autonomic control requires more than 10 min to fully recover after intense physical exertion of only 30-s in young healthy males.     

Skipping breakfast: gender effects on resting heart rate measures in preadolescents

The cardiovascular response in children to morning nutrition has received little attention, and associated gender-related effects are virtually uninvestigated. This study evaluated resting heart-rate (HR) and heart-rate variability (HRV) in preadolescents after overnight fasting and again after eating a standardized breakfast or continuing to fast. HR increased slightly after eating and decreased significantly with continued fasting. These effects were present for both sexes. Relative to children who ate, those who continued fasting showed increases in HRV-particularly for inter-beat-interval and low frequency component (LF: 0.04-0.15 Hz) measures. Analyses revealed significant increases across variability measures for fasting children, but a selective LF decrease in those who were fed-an effect most prominent in females. Otherwise, males and females showed similar treatment-related changes in HRV. While within-gender comparisons showed similar results for HR, i.e., faster HR in fed compared with fasting males and females, respectively, fasting females-but not males-showed significantly greater increases in variability relative to their fed counterparts. Together, these findings suggest that extended overnight fasting initiates an increase in parasympathetic activity that attenuates the expected increase in cardiovascular output following a mid-morning meal. Observed gender differences were related to greater parasympathetic activity in males and to the apparent emphasis on parasympathetic regulation of LF variability. The implications of these findings for health concerns, the nature of responses to physiological and cognitive stressors, and how such differences may influence performance variables-particularly early in development when cardiovascular responses to these stressors may be more sensitive to nutritional factors-are discussed.     

Intraindividual analysis of instantaneous heart rate variability

We examined the use and potential of quantifying instantaneous heart rate variability (HRV) using a joint time-frequency and time-domain methods. These new techniques are promising, because they provide tools to quantify nonstationary, beat-by-beat changes in HRV components, and are therefore flexible with respect to the design of experimental protocols. A smoothed pseudo-Wigner-Ville distribution (SPWVD) and a time-domain index using polynomial filtering produced fairly coherent estimates of band-specific HRV amplitudes, whereas SPWVD yielded additional information on the frequency characteristics of HRV. Instantaneous HRV appeared to have a complex and a frequency-specific relationship to cardiac activity and electrodermal activity, It is concluded that the time-frequency analysis of HRV is a very promising method for mapping transient changes in the frequency and amplitude characteristics of cardiac dynamics.     

Spectral analysis of heart rate variability using the integral pulse frequency modulation model

Spectral analysis of heart rate variability (HRV) is a widely accepted approach for assessment of cardiac autonomic function and its relationship to numerous disorders and diseases. As a rule, the non-parametric methods for HRV spectral analysis are tested using the integral pulse frequency modulation (IPFM) model. However, published results with simulated HRV signals show differences requiring further development of the existing methods. With the aim of improving estimation accuracy, an entirely IPFM-based method for HRV analysis is investigated. According to this method, the spectra are computed by finding the least squares solution of two matrix equations that are derived using the IPFM model and involve irregular samples of a signal representing the HRV. The method is validated with various synthesised signals (in all tests, the relative errors of the power estimates at the modulating frequencies are within 3%, and the relative power of the spurious terms is less than 0.8% only) and is furthermore applied to the spectral analysis of RR interval series obtained from diabetic children. The results, with simulated and real HRV signals, show that the developed method yields very accurate estimations of the spectral region below half the mean heart rate. Moreover, it allows the detection and assessment of certain genuine modulating components beyond the traditional frequency limit of the HRV spectra.     

Impact of chronic obstructive pulmonary disease on linear and nonlinear dynamics of heart rate variability in patients with heart failure

The objective of this study was to investigate the impact of chronic obstructive pulmonary disease (COPD)-heart failure (HF) coexistence on linear and nonlinear dynamics of heart rate variability (HRV). Forty-one patients (14 with COPD-HF and 27 HF) were enrolled and underwent pulmonary function and echocardiography evaluation to confirm the clinical diagnosis. Heart rate (HR) and R-R intervals (iRR) were collected during active postural maneuver (APM) [supine (10 min) to orthostasis (10 min)], respiratory sinus arrhythmia maneuver (RSA-M) (4 min), and analysis of frequency domain, time domain, and nonlinear HRV. We found expected autonomic response during orthostatic changes with reduction of mean iRR, root mean square of successive differences between heart beats (RMSSD), RR tri index, and high-frequency [HF (nu)] and an increased mean HR, low-frequency [LF (nu)], and LF/HF (nu) compared with supine only in HF patients (P<0.05). Patients with COPD-HF coexistence did not respond to postural change. In addition, in the orthostatic position, higher HF nu and lower LF nu and LF/HF (nu) were observed in COPD-HF compared with HF patients. HF patients showed an opposite response during RSA-M, with increased sympathetic modulation (LF nu) and reduced parasympathetic modulation (HF nu) (P<0.05) compared with COPD-HF patients. COPD-HF directly influenced cardiac autonomic modulation during active postural change and controlled breathing, demonstrating an autonomic imbalance during sympathetic and parasympathetic maneuvers compared with isolated HF.     

Heart rate discrimination and heart rate control: a test of Brener's theory

Three experiments were conducted to examine predictions from Brener's theory regarding the relationship between autonomic discrimination and autonomic control. Experiment 1 examined the possibility that training subjects to discriminate their heart rates would enhance their skill at controlling that response. Twenty subjects participated in two sessions during which one group of 10 subjects received training (knowledge of results) on the Ashton discrimination technique. The second group performed the discrimination task but received no training. All subjects then took part in a third session of heart rate (HR) control (both increase and decrease) where half of each of the aforementioned groups received feedback during the control task, while the other half performed the HR control task without feedback. Results indicated that for the control of both HR increases and decreases, there was no significant difference between those subjects trained to discriminate their HR, and those who had received no training to discriminate HR. The second experiment investigated the hypothesis that training subjects with feedback to control their HR would enhance their capacity to discriminate their heart activity. Ten subjects participated in two sessions of HR control during which half the subjects received feedback training to increase HR. During a third session, all subjects underwent a test of discrimination ability using the Ashton technique, and no knowledge of results regarding performance was provided. Results confirmed the hypothesis. The final experiment in the series investigated the discrimination/control relationship within a problem-solving framework and used 20 subjects. Results confirmed the hypothesis that subjects forewarned at the time of discrimination training that a heart rate control task was to follow would perform better than 10 subjects receiving no forewarning of the task objective. This effect took place independently of cardiac discrimination ability. A second finding from this experiment was that subjects trained to discriminate heart rate were better able to increase heart rate than untrained subjects. This result contradicts that of Experiment 1, and reasons for this anomaly are discussed in detail.     

Heart rate variability in relation to cognition and behavior in neurodegenerative diseases: A systematic review and meta-analysis

Neurodegenerative diseases, which frequently present with neuropsychiatric symptoms related to prefrontal cortical dysfunction, can alter the integrity of the neural networks involved in central autonomic nervous system regulation, which is proposed to be indexed by heart rate variability (HRV). We systematically reviewed the characteristics, methodology and outcomes of 27 studies of HRV in relation to measures of cognition and behavior in neurodegenerative conditions, and assessed the strength of this relationship, cross-sectionally, across 18 studies. A significant, moderate effect was observed (r = 0.25), such that higher HRV was related to better cognitive and behavioral scores, which was not influenced by mean age or cognitive status. There was no evidence of small-study effects but we could not rule out publication bias, and other factors may have contributed to heterogeneity between studies. Our findings support the proposal that HRV may be a marker of self-regulatory processes in neurodegenerative conditions, and further research on this association is needed in relation to neuropsychiatric symptoms and alongside neuroimaging methods.