Heart rate variability biofeedback, executive functioning and chronic brain injury

Heart rate and heart rate variability in obsessive-compulsive disorder: Evidence from patients and unaffected first-degree relatives

Altered heart rate (HR) and heart rate variability (HRV) are common observations in psychiatric disorders. Yet, few studies have examined these cardiac measures in obsessive-compulsive disorder (OCD). The current study aimed to investigate HR and HRV, indexed by the root mean square of successive differences (RMSSD) and further time domain indices, as putative biological characteristics of OCD. Electrocardiogram was recorded during a five-minute resting state. Group differences between patients with OCD (n = 96), healthy participants (n = 112), and unaffected first-degree relatives of patients with OCD (n = 47) were analyzed. As potential moderators of group differences, we examined the influence of age and medication, respectively. As results indicated, patients with OCD showed higher HR and lower HRV compared to healthy participants. These group differences were not moderated by age. Importantly, subgroup analyses showed that only medicated patients displayed lower HRV compared to healthy individuals, while HR alterations were evident in unmedicated patients. Regarding unaffected first-degree relatives, group differences in HRV remained at trend level. Further, an age-moderated group differentiation showed that higher HRV distinguished relatives from healthy individuals in young adulthood, whereas at higher age lower HRV was indicative of relatives. Both the role of familial risk and medication in HRV alterations need further elucidation. Pending future studies, alterations in HR and potentially HRV might serve as useful indices to characterize the pathophysiology of OCD.

Validation of Photoplethysmography Using a Mobile Phone Application for the Assessment of Heart Rate Variability in the Context of Heart Rate Variability-Biofeedback

OBJECTIVE

Heart rate variability-biofeedback (HRV-BF) is an effective intervention to reduce stress and anxiety and requires accurate measures of real-time HRV. HRV can be measured through photoplethysmography (PPG) using the camera of a mobile phone. No studies have directly compared HRV-BF supported through PPG against classical electrocardiogram (ECG). The current study aimed to validate PPG HRV measurements during HRV-BF against ECG.

METHODS

Fifty-seven healthy participants (70% women) with a mean (standard deviation) age of 26.70 (9.86) years received HRV-BF in the laboratory. Participants filled out questionnaires and performed five times a 5-minute diaphragmatic breathing exercise at different paces (range, ~6.5 to ~4.5 breaths/min). Four HRV indices obtained through PPG, using the Happitech software development kit, and ECG, using the validated NeXus apparatus, were calculated and compared: RMSSD, pNN50, LFpower, and HFpower. Resonance frequency (i.e., optimal breathing pace) was also compared between methods.

RESULTS

All intraclass correlation coefficient values of the five different breathing paces were "near perfect" (>0.90) for all HRV indices: lnRMSSD, lnpNN50, lnLFpower, and lnHFpower. All Bland-Altman analyses (with just three incidental exceptions) showed good interchangeability of PPG- and ECG-derived HRV indices. No systematic evidence for proportional bias was found for any of the HRV indices. In addition, correspondence in resonance frequency detection was good with 76.6% agreement between PPG and ECG.

CONCLUSIONS

PPG is a potentially reliable and valid method for the assessment of HRV. PPG is a promising replacement of ECG assessment to measure resonance frequency during HRV-BF.

Reducing decision-making deficits in patients with brain injury: effect of slow-paced breathing

Impairments in decision-making have been reported in brain-damaged (stroke/traumatic brain injury) patients with a wide range of lesion sites. Here, we propose that the performances of patients in complex sequential decision-making (DM) tasks can be explained by their negative affectivity, leading to deliberative processing associated with poor DM performances. We assumed that a slow-paced breathing (SPB) training, by reducing negative affectivity would improve performances in a complex DM task. For 24 days, 34 brain-damaged patients (16 males and 18 females; 12 had a hemorrhagic stroke, 17 with an ischemic stroke and 5 with a TBI), practiced either daily SPB or sham trainings for five min, three times a day. Before and after training, we assessed their vagal tone (electrocardiogram-ECG), affectivity (Positive and Negative Affect Schedule-PANAS) and certainty level (Dimensional Ratings Questionnaire-DRQ) and their performance on the Iowa Gambling Task. All participants showed initial weak performance, which improved only for patients in the SPB training condition. These results suggest that DM disorders in brain-damaged patients can be the consequence of their poor information processing strategy rather than an impairment in their DM abilities. Second, we showed that SPB could be efficient to normalize DM processes in brain injury patients.

Managing challenging behaviours in adults with traumatic brain injury: A scoping review of technology-based interventions

Challenging behaviours are one of the most serious sequelae after a traumatic brain injury (TBI). These chronic behaviours must be managed to reduce the associated burden for caregivers, and people with TBI. Though technology-based interventions have shown potential for managing challenging behaviours, no review has synthesised evidence of technology aided behaviour management in the TBI population. The objective of this scoping review was to explore what technology-based interventions are being used to manage challenging behaviours in people with TBI. Two independent reviewers analysed 3505 studies conducted between 2000 and 2023. Studies were selected from five databases using search strategies developed in collaboration with a university librarian. Sixteen studies were selected. Most studies used biofeedback and mobile applications, primarily targeting emotional dysregulation. These technologies were tested in a variety of settings. Two interventions involved both people with TBI and their family caregivers. This review found that technology-based interventions have the potential to support behavioural management, though research and technology development is at an early stage. Future research is needed to further develop technology-based interventions that target diverse challenging behaviours, and to document their effectiveness and acceptability for use by people with TBI and their families.

Reducing Anxiety and Social Stress in Primary Education: A Breath-Focused Heart Rate Variability Biofeedback Intervention

Primary school students suffer from high levels of anxiety and stress. Having emotional regulation abilities can help them to manage challenging emotional situations. Conscious and slow breathing is a physiological, emotional regulation strategy that is feasible for primary school students to learn. Following Polyvagal Theory and PMER Theory, this research presents the results of a breath-focused heart rate variability biofeedback intervention. The intervention aimed to reduce anxiety and physiological and social stress in primary school children. A total of 585 students (46.4% girls and 53.6% boys) from the same public school, aged between 7 and 12 years (M = 8.51; SD = 1.26), participated in this study. To assess the impact of training, a mixed design was used with two groups (Treatment and Control groups), two evaluation phases (Pretest and Post-test), and three educational cycles (first, second and third cycles). To examine heart rate variability, emWave software was used and anxiety and social stress were measured by the BASC II test. The results showed that after the intervention, the students learned to breathe consciously. Moreover, they reduced their levels of anxiety (M(SD)_pretest = 12.81(2.22) vs. M(SD)_posttest = 13.70(1.98)) and stress (M(SD)_pretest = 12.20(1.68) vs. M(SD)_posttest = 12.90(1.44)). The work also discusses the limitations and benefits of this type of intervention in primary schools.

Evaluation of the Heart Rhythm Coherence Ratio During Sleep: A Pilot Study With Polysomnography

The psychophysiological coherence model proposes that a heart rhythm pattern, known as heart rhythm coherence (HRC), is associated with dominant parasympathetic activity and the entrainment of respiratory function, blood pressure, and heart rhythms. Although the HRC pattern has primarily been assessed during wakefulness, changes in cardiac and autonomic activity that occur during sleep stages can also be associated with the HRC pattern. The objective of this study was to examine whether any differences in the HRC pattern could be detected among various sleep stages. Eighteen healthy young individuals participated in this study. Two consecutive polysomnographic (PSG) recordings were obtained from each participant, several segments of cardiac activity were obtained from the second PSG. The HRC pattern was quantitatively evaluated by calculating the HRC ratio (HRCR). The highest peaks in the coherence band (Coher-Peak), 0.1-Hz index, respiratory sinus arrhythmia (RSA), and heart rate (HR) were evaluated. A Friedman test showed significant differences among sleep stages in the Coher-Peak, 0.1-Hz index, RSA, and HR; the Coher-Peak and RSA values were lower in rapid eye movement (REM) sleep, while the 0.1-Hz and HR values were higher in REM sleep. Post hoc analyses identified significant differences between the N2 and REM sleep stages. Among the various sleep stages, HR and RSA measurements behaved independently of the HRC pattern, and the HRC pattern did not appear to be associated with the 0.1 Hz frequency. Further studies are required to identify the characteristics of the HRC pattern during sleep.

Neurobehavioral Symptoms and Heart Rate Variability: Feasibility of Remote Collection Using Mobile Health Technology

OBJECTIVES

To determine the covariance of heart rate variability (HRV) and self-reported neurobehavioral symptoms after traumatic brain injury (TBI) collected using mobile health (mHealth) technology.

SETTING

Community.

PARTICIPANTS

Adults with lifetime history of TBI (n = 52) and adults with no history of brain injury (n = 12).

DESIGN

Two-week prospective ecological momentary assessment study.

MAIN MEASURES

Behavioral Assessment Screening Tool (BASTmHealth) subscales (Negative Affect, Fatigue, Executive Dysfunction, Substance Abuse, and Impulsivity) measured frequency of neurobehavioral symptoms via a RedCap link sent by text message. Resting HRV (root mean square of successive R-R interval differences) was measured for 5 minutes every morning upon waking using a commercially available heart rate monitor (Polar H10, paired with Elite HRV app).

RESULTS

Data for n = 48 (n = 38 with TBI; n = 10 without TBI) participants were included in covariance analyses, with average cross-correlation coefficients (0-day lag) varying greatly across participants. We found that the presence and direction of the relationship between HRV and neurobehavioral symptoms varied from person to person. Cross-correlation coefficients r ≤ -0.30, observed in 27.1% to 29.2% of participants for Negative Affect, Executive Dysfunction, and Fatigue, 22.9% of participants for Impulsivity, and only 10.4% of participants for Substance Abuse, supported our hypothesis that lower HRV would covary with more frequent symptoms. However, we also found 2.0% to 20.8% of participants had positive cross-correlations (r ≥ 0.30) across all subscales, indicating that higher HRV may sometimes correlate with more neurobehavioral symptoms, and 54.2% to 87.5% had no significant cross-correlations.

CONCLUSIONS

It is generally feasible for community-dwelling adults with and without TBI to use a commercially available wearable device to capture daily HRV measures and to complete a short, electronic self-reported neurobehavioral symptom measure for a 2-week period. The covariance of HRV and neurobehavioral symptoms over time suggests that HRV could be used as a relevant physiological biomarker of neurobehavioral symptoms, though how it would be interpreted and used in practice would vary on a person-by-person and symptom domain basis and requires further study.

Biofeedback as an intervention for persistent post-concussive symptoms: A randomized feasibility trial

Background

Case reports indicate that low-resolution electromagnetic tomography neurofeedback and heart rate variability biofeedback may improve physiological functioning in individuals with persistent post-concussive symptoms. However, it is unclear whether larger-scale studies are feasible.

Purpose

To evaluate the feasibility of a combined low-resolution electromagnetic tomography neurofeedback and heart rate variability biofeedback intervention for individuals with persistent post-concussive symptoms.

Methods

Individuals with persistent post-concussive symptoms were randomized into intervention and control groups, and their baseline and post-test assessments were compared to a healthy control group. Outcomes included self-report questionnaires, resting electroencephalograph and electrocardiograph recordings, and a driving simulation task. Participants in the intervention group completed three 20 min low-resolution electromagnetic tomography neurofeedback sessions per week and at-home heart rate variability biofeedback training every morning and night for 8 weeks. Feasibility was evaluated according to recruitment capability and sample characteristics, data collection procedures, suitability of the intervention and study procedures, management and implementation of the study intervention, and preliminary participant responses to the intervention.

Results

Thirty-three individuals were recruited and 24 completed this study (seven intervention participants, nine persistent post-concussive symptoms control participants, and eight healthy control participants). One-quarter of participants (four intervention participants and three persistent post-concussive symptoms control participants) experienced simulator sickness during the driving simulator task and had to withdraw from the study. Intervention participants had an 88% and 86% compliance rate for the low-resolution electromagnetic tomography neurofeedback and heart rate variability biofeedback sessions, respectively. Low-resolution electromagnetic tomography neurofeedback sessions took approximately 1 h to complete per participant. Preliminary analysis indicated that the intervention reduced electroencephalograph z-score deviation with a very large effect size ( d = 1.36) compared to the other study groups.

Conclusions

Pilot studies evaluating the efficacy of low-resolution electromagnetic tomography neurofeedback and heart rate variability biofeedback should be performed to confirm these preliminary findings. However, the protocol should be modified to reduce participant fatigue and withdrawal. This trial was registered with Clinicialtrials.gov (NCT03338036; https://clinicaltrials.gov/ct2/show/NCT03338036?term=03338036&draw=2&rank=1 ).

Regulating emotion following severe traumatic brain injury: a randomized controlled trial of heart-rate variability biofeedback training

BACKGROUND

While difficulties regulating emotions are almost ubiquitous after traumatic brain injury (TBI), remediation techniques are limited. Heart-rate variability (HRV) is a physiological measure of emotion regulation and can be modified using biofeedback training. The aim of the current study was to evaluate the efficacy of repeated biofeedback training for improving emotion regulation difficulties following TBI.

DESIGN

Fifty adults with severe TBI were allocated to either biofeedback or waitlist conditions. Treatment consisted of six biofeedback sessions whereby participants were taught to breathe at their resonant frequency. Outcomes included changes in physiological and subjective reactivity to anger-induction, emotional well-being, and physiology at rest, together with symptoms of psychological distress and sleep disturbances (ACTRN12618002031246).

RESULTS

While biofeedback led to reduced skin conductance, it did not affect any other objective or subjective response to the mood induction procedure. Biofeedback led to fewer sleep disturbances, and reduced negative mood valence and depression during follow-up.

CONCLUSIONS

HRV biofeedback training is a feasible technique following TBI that transfers to improved symptoms of general emotional well-being, psychological distress, and sleep. Biofeedback does not transfer to a laboratory-based emotional provocation task. HRV biofeedback training may represent a novel adjunct for generalized emotional difficulties following injury.

Does Heart Rate Variability Biofeedback Enhance Executive Functions Across the Lifespan? A Systematic Review

The scope of this systematic review was to summarize the existing literature on the effects of heart rate variability biofeedback (HRV-BF) on executive functions (EFs) across the lifespan. Specifically, it aimed to investigate the factors that may affect the efficacy of HRV-BF interventions, such as the study population, duration and intensity of the intervention, or the technical equipment. This review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies that measured and presented at least one EF were included. We included controlled and uncontrolled trials involving clinical and general populations. From the initial list of 137 papers, 16 final studies were reviewed, with 777 participants. Fifty-six percent of the studies included in this review reported significant positive effects of HRV-BF intervention on at least one EF. Attention was the domain that most often benefited from the intervention. The majority of EF improvements (78%) occurred in studies that addressed patient populations or individuals that may present particular profiles: individuals exposed to stress, professional athletes, war veterans, children and adults with ADHD, and clinical older patients. The remaining studies (22%) that reported significant improvements focused on the general population. Efficacy was neither related to the duration or intensity of the intervention nor related to the technical equipment. Overall, our review shows that HRV-BF may be beneficial (a) to increase attentional skills, inhibition, and working memory and (b) when targeting more vulnerable individuals or individuals with particular profiles. However, further development of standardized, controlled protocols and consistent reporting of effect sizes may contribute to establishing the relevance of HRV-BF biofeedback interventions within the field of cognitive enhancement.

Heart rate variability biofeedback in chronic disease management: A systematic review

BACKGROUND

Heart rate variability biofeedback (HRVB) is a non-pharmacological intervention used in the management of chronic diseases.

METHOD

A systematic search was performed according to eligibility criteria including adult chronic patients, HRVB as main treatment with or without control conditions, and psychophysiological outcomes as dependent variables.

RESULTS

In total, 29 articles were included. Reported results showed the feasibility of HRVB in chronic patients without adverse effects. Significant positive effects were found in various patient profiles on hypertension and cardiovascular prognosis, inflammatory state, asthma disorders, depression and anxiety, sleep disturbances, cognitive performance and pain, which could be associated with improved quality of life. Improvements in clinical outcomes co-occurred with improvements in heart rate variability, suggesting possible regulatory effect of HRVB on autonomic function.

CONCLUSIONS

HRVB could be effective in managing patients with chronic diseases. Further investigations are required to confirm these results and recommend the most effective method.

Does Double Biofeedback Affect Functional Hemispheric Asymmetry and Activity? A Pilot Study

In the current pilot study, we attempt to find out how double neurofeedback influences functional hemispheric asymmetry and activity. We examined 30 healthy participants (8 males; 22 females, mean age = 29; SD = 8). To measure functional hemispheric asymmetry and activity, we used computer laterometry in the ‘two-source’ lead-lag dichotic paradigm. Double biofeedback included 8 min of EEG oscillation recording with five minutes of basic mode. During the basic mode, the current amplitude of the EEG oscillator gets transformed into feedback sounds while the current amplitude of alpha EEG oscillator is used to modulate the intensity of light signals. Double neurofeedback did not directly influence the asymmetry itself but accelerated individual sound perception characteristics during dichotic listening in the preceding effect paradigm. Further research is needed to investigate the effect of double neurofeedback training on functional brain activity and asymmetry, taking into account participants’ age, gender, and motivation.

Real-time monitoring of barriers to patient engagement for improved rehabilitation: a protocol and representative case reports

PURPOSE

There is ample evidence that patient engagement is of major clinical importance in rehabilitation, and it seems this engagement is based upon effective allocation of attention to the tasks during the rehabilitation session. It is possible to discern two types of barriers which hinder attentive engagement: (1) dysfunctional affective coping and (2) limited cognitive recruitment and specifically attention deficit. These barriers might be general for a given patient, due to pre-morbid or co-morbid dysfunctions. But more often they are evoked by tasks or challenges during the rehabilitation session which might be too complicated or stressing for the specific patient who copes with potentially grave impairments. These barriers hinder rehabilitation progress and should be monitored and overcome, by the therapist, throughout the session.

METHODS

We have developed an easy-to-use tool for monitoring a patient's attentive engagement in real-time throughout a rehabilitation session based on analysing the electrophysiological signal sampled from a simple headset. The tool then analyzes the dynamics of the marker over time to identify cognitive and affective barriers during the session. It enables the therapist to insert feedback regarding the patient's functional performance and to combine it with the analysed barriers, in order to derive automatic recommendations for overcoming the cognitive and affective barriers (if identified) for significant enhancement of the rehabilitation session.

RESULTS AND CONCLUSIONS

In this work we present the principles of the tool as well as three detailed case reports to demonstrate its potential usefulness.IMPLICATIONS FOR REHABILITATIONCognitive and affective barriers hinder patient engagment and rehabilitation success.In this work we present an easy to use electrophysiology-based tool which monitors these barriers.Based on the measured barriers and patient's performance, the tool derives treatment suggestions.

Daily self-regulation with biofeedback to improve stress and job satisfaction in a primary care clinic

BACKGROUND

Burnout in healthcare professions is higher than other careers. An undesirable work-life balance has resulted in declining job satisfaction among primary care physicians. Biofeedback devices teach self-regulation techniques, which reduce stress and increase resilience.

OBJECTIVES

We assessed whether self-regulation with biofeedback is effective at decreasing stress and improving job satisfaction among primary care clinicians and nurses.

METHODS

Two naturally occurring cohorts of clinicians and nurses were followed over 12 weeks. The treatment group (N = 9) completed 12 weeks of self-regulation with optional clinic-based biofeedback and received peer support for the first half. The control group (N = 9) started a delayed intervention after 6 weeks without peer support. Descriptive and bivariate analyses were conducted.

RESULTS

The treatment group averaged one biofeedback session weekly for 6 min and the control group two sessions for 11 min. Adherence differed by age. Subjects also reported using self-regulation techniques without biofeedback. Perceived stress initially increased in both groups with intervention implementation, more so in the treatment group (P = 0.03) whose stress then decreased but was not significant. Overall and extrinsic job satisfaction similarly increased but were not significance.

CONCLUSION

The initial increase in perceived stress was related to daily biofeedback adherence and clinic responsibilities. Treatment group stress then decreased with self-regulation but was difficult to quantify in a small cohort. Larger studies could increase daily self-regulation adherence by improving biofeedback accessibility for leisurely use. Using self-regulation with biofeedback may be an innovative approach to reduce stress and improve job satisfaction in primary care.

Biocueing and ambulatory biofeedback to enhance emotion regulation: A review of studies investigating non-psychiatric and psychiatric populations

Over the last years, biofeedback applications are increasingly used to enhance interoceptive awareness and self-regulation, in psychiatry and beyond. These applications are used to strengthen emotion regulation skills by home training (ambulatory biofeedback) and real-time support in everyday life stressful situations (biocueing). Unfortunately, knowledge about the feasibility and effectivity of these applications is still scarce. Therefore, a systematic literature search was performed. In total, 30 studies (4 biocueing, 26 ambulatory biofeedback) were reviewed; 21 of these studies were conducted in non-psychiatric samples and 9 studies in psychiatric samples. Study characteristics, biofeedback characteristics, effectivity and feasibility outcomes were extracted. Despite the rapid advances in wearable technology, only a few biocueing studies were found. In the majority of the studies significant positive effects were found on self-reported (stress-related) psychological measures. Significant improvements on physiological measures were also reported, though these measures were used less frequently. Feasibility of the applications was often reported as sufficient, though not adequately assessed in most studies. Taken into account the small sample sizes and the limited quality of the majority of the studies in this recently emerging field, biocueing and ambulatory biofeedback interventions showed promising results. Future research is expected to be focusing on biocueing as a just-in-time adaptive intervention. To establish this research field, closer cooperation between research groups, use of more rigorous as well as individually tailored research designs and more valid feasibility and effectivity assessment are recommended.

Can biofeedback-based training alleviate fatigue and vigilance performance in fatigued MS patients?

MS related fatigue might be related to autonomous nervous system (ANS) dysfunctions or to inflammation related vagal (hyper-) activation. Consequently, influencing ANS status may lead to relieve of fatigue. We used two opposite biofeedback interventions to either increase sympathetic ("self-alert training", SAT) or parasympathetic activation ("progressive muscle relaxation", PMR). We recorded fatigue status of patients before and after a challenging vigilance task, their behavioural performance on this task, their skin conductance response (SCR), and parameters indicating parasympathetic activity concerning heart rate variability (HRV). We repeated these recordings after the biofeedback training sessions. Patients of the SAT group were able to learn to increase their SCR voluntarily. Patients of the PMR group showed increasing parameters indicating parasympathetic modulation of the HRV. The vigilance task increased their feeling of fatigue. However, there was no effect of biofeedback training on either fatigue status or performance on the vigilance task. Our results show that MS patients can learn to change voluntarily their ANS activity using biofeedback instructions based on SCR and this can be used in future studies to test the postulated link between ANS and fatigue. However, in this experimental intervention we were unable to document a relation between ANS activity and fatigue.Trial registration: ClinicalTrials.gov identifier: NCT03268187.

Loneliness and Telomere Length: Immune and Parasympathetic Function in Associations With Accelerated Aging

BACKGROUND

Lonely people's heightened risks for chronic health conditions and early mortality may emerge in part through cellular aging. Lonelier people have more severe sympathetic responses to acute stress, increasing their risk for herpesvirus reactivation, a possible path to shorter telomeres. Parasympathetic function may modulate this risk.

PURPOSE

The current study aimed to examine the associations among loneliness, herpesvirus reactivation, and telomere length, with parasympathetic activity as a moderator, in healthy middle-aged and older adults.

METHODS

A sample of 113 healthy men and women of ages 40-85 provided blood samples that were assayed for telomere length, as well as the latent herpesviruses cytomegalovirus (CMV) and Epstein-Barr virus (EBV). They also provided heart rate variability (HRV), a measure of parasympathetic activity, and reported on their feelings of loneliness.

RESULTS

Lonelier people with lower HRV (i.e., lower parasympathetic activity) had greater CMV reactivation and shorter telomeres compared with their less lonely counterparts, above and beyond demographics, health behaviors, resting heart rate, and social network size. However, loneliness was not associated with viral reactivation or telomere length among those with higher HRV. In turn, greater CMV and EBV reactivation was associated with shorter telomeres.

CONCLUSIONS

Taken together, these data implicate parasympathetic function in novel links between loneliness and accelerated cellular aging.

Pediatric Traumatic Brain Injury and Exercise Medicine: A Narrative Review

The multidisciplinary field of pediatric traumatic brain injury (TBI) and exercise medicine is of growing importance. There is active study into the diagnostic and therapeutic potential of exercise in pediatric TBI as well as the effects of TBI on postinjury fitness. With the evidence-based growing, a literature review can help establish the state of the science and inform future research. Therefore, the authors performed a narrative review (based on a search of 6 health sciences databases) to summarize evidence on pediatric TBI and cardiorespiratory fitness, muscular fitness and neuromotor control, and obesity. To date, studies related to cardiorespiratory fitness have centered on exercise tolerance and readiness to return to play, and indicate that protracted rest may not facilitate symptom recovery; this suggests a role for exercise in concussion management. Furthermore, strength and gait may be impaired following pediatric brain injury, and interventions designed to train these impairments may lead to their improvement. Pediatric brain injury can also lead to changes in body composition (which may be related to poorer cognitive recovery), but additional research is required to better understand such associations. This narrative review of pediatric TBI and exercise medicine can serve as a reference for researchers and clinicians alike.

Effects of Heart Rate Variability Biofeedback in Patients With Acute Ischemic Stroke: A Randomized Controlled Trial

BACKGROUND

Autonomic dysfunction, cognitive impairment, and psychological distress are associated with poorer prognosis in patients with acute ischemic stroke (AIS). Heart rate variability (HRV) biofeedback (BF) improves autonomic dysfunction, cognitive impairment, and psychological distress in other patient populations, but its effect in patients with AIS is still unclear.

OBJECTIVE

This study investigated the effects of an HRVBF intervention on autonomic function, cognitive impairment, and psychological distress in patients with AIS.

METHOD

In this randomized, controlled, single-blind trial, patients with AIS were randomly assigned to the experimental or control group. The experimental group received four HRVBF training sessions. The control group received usual care. Repeated measures of HRV, mini-mental status examination (MMSE), and Hospital Anxiety and Depression Scales (HADS) were collected prior to and at 1 and 3 months postintervention.

RESULTS

A total of 35 patients completed the study (19 experimental, 16 control). HRV and HADS significantly improved in the experimental group (p < .001) but not in the control group. Likewise, only the experimental group showed significant improvements in HRV, MMSE, and HADS over time (p < .05).

CONCLUSION

HRVBF is a promising intervention for improving autonomic function, cognitive impairment, and psychological distress in patients with AIS. More studies of HRVBF interventions are needed to further optimize the effects of HRVBF on autonomic, cognitive, and psychological function in patients with AIS.

Heart Rate Variability Biofeedback Based on Slow-Paced Breathing With Immersive Virtual Reality Nature Scenery

This study investigated the benefits of using a virtual nature environment to administer immersive heart rate variability biofeedback (HRV-BF) based on slow-paced breathing. We compared the virtual reality (VR)-based HRV-BF with a standard implementation in a randomized controlled experiment with 60 healthy employees. After a cognitive stress induction, the participants performed a single-session of HRV-BF before repeating the cognitive stressor task. VR-based versus standard HRV-BF was comparable in terms of biofeedback performance (cardiac coherence and cardiac vagal tone). However, the VR-based implementation buffered perceived stress in the subsequent stressor task, increased relaxation self-efficacy more, reduced mind wandering, helped participants focus on the present moment, and helped preserve attentional resources. Potential long-term effects and generalizability need to be assessed in future research.

Heart rate variability biofeedback: implications for cognitive and psychiatric effects in older adults

OBJECTIVES

Two decades of heart rate variability (HRV) biofeedback research have focused on adolescent and adult populations with a variety of symptoms and conditions at the exclusion of older adults. This study explores HRV biofeedback as a novel treatment to decrease psychiatric symptoms and improve cognitive functioning in older adults.

METHODS

Participants enrolled in a three-week intervention that included six 30-min biofeedback sessions. Neuropsychological and psychiatric measures were administered before and after the intervention.

RESULTS

Decreases in depression (Cohen's d = 1.02, p < .001), state anxiety (Cohen's d = 0.82, p = .003), and trait anxiety (Cohen's d = 0.84, p = .002) were observed. An increase in attentional skills as measured by the Trail Making Test - Part A was seen (Cohen's d = 1.00, p = .001). Differences in executive skills as measured by the Trial Making Test - Part B and the Stroop Task did not reach statistical significance.

CONCLUSION

This study suggests that older adults may benefit from HRV biofeedback interventions much like the younger populations that have been studied for decades. Depression, anxiety, and attentional skills were positively affected. Several participants reported improved sleep quality and stress management. Future studies should corroborate these findings.

Emotion regulation after acquired brain injury: a study of heart rate variability, attentional control, and psychophysiology

Primary objective: To examine the efficacy of heart rate variability biofeedback (HRV-BF) to treat emotional dysregulation in persons with acquired brain injury. Design: A secondary analysis of a quasi-experimental study which enrolled 13 individuals with severe chronic acquired brain injury participating in a community-based programme. Response-to-treatment was measured with two HRV resonance indices (low frequency activity [LF] and low frequency/high frequency ratio [LF/HF]). Main outcome: Behavior Rating Inventory of Executive Function-informant report (emotional control subscale [EC]). Results: Results show significant correlation between LF and EC with higher LF activity associated with greater emotional control; the association between LF/HF pre-post-change score and EC is not statistically significant. A moderation model, however, demonstrates a significant influence of attention on the relation between LF/HF change and EC when attention level is high, with an increase in LF/HF activity associated with greater emotional control. Conclusions: HRV-BF is associated with large increases in HRV, and it appears to be useful for the treatment of emotional dysregulation in individuals with severe acquired brain injury. Attention training may enhance an individual's emotional control.

Shift Work and Heart Rate Variability Coherence: Pilot Study Among Nurses

This study used ambient heart rate monitoring among health care workers to determine whether a novel measure of heart rate variability (HRV), as well as sleep disturbances, fatigue, or cognitive performance differed among non-rotating night shift nurses relative to those working permanent day shifts. Continuous ambulatory HRV monitoring was performed among night nurses (n = 11), and a comparison group of permanent day nurses (n = 7), over a 36-h period coinciding with the last two 12-h shifts of each participant's work week. Symptoms and psychomotor vigilance were assessed at the end of the ambient HRV monitoring period, and no differences between shifts were observed. Day nurses exhibited an increase in hourly mean HRV coherence ratios during their sleep period, suggesting a circadian pattern of cardiorespiratory phase coupling, whereas night nurses had no increase in HRV coherence ratios during their sleep period. The HRV coherence patterns were similar to high frequency HRV power among nurses on the same shift. To the authors knowledge, this study was the first to quantify patterns of the HRV coherence ratio among shiftworkers in a non-experimental (work/home) setting. The results suggest a pattern of autonomic dysregulation among night workers during their sleep period relative to those working day shifts. The HRV coherence ratio may serve as a novel indicator of HRV dysregulation among shift workers.

One-minute heart rate variability - an adjunct for airway obstruction identification

Heart rate variability (HRV) reflects cardiac and autonomic nervous system activity. It is usually measured over a relatively prolonged period and presented using multiple parameters. Here, we studied rapid HRV changes during airway obstruction using a short (1 min) sampling window. Forty healthy volunteers underwent a trial of obstructed breathing. Heart rate was recorded during three consecutive sets comprised of 1-min control followed by 1 min of obstructed breathing, with 1 min of rest between sets. Time and frequency domain analysis were used to compare HRV during control versus obstructed breathing. Compared with control, HRV intensely increased during obstructed breathing: R-R intervals (time between consecutive R waves) standard deviation increased from 65 to 108 msec (P < 0.0001), root mean square of successive R-R interval from 61 to 82 msec (P = 0.001), number of pairs of successive R-R intervals that differ by more than 50 msec (NN50) from 16.5 to 25.3 events (P < 0.0001), and proportion of NN50 divided by total number of R-R intervals from 26.6 to 35.1% (P = 0.001). Low frequency power increased by more than fourfold (P < 0.0001), allowing 90% sensitivity and 75% specificity for identifying airway obstruction (ROC area 0.88, P < 0.0001). We observed a rapid intense increase in HRV during obstructed breathing, significant enough to detect during a short 1-min sampling window. These findings suggest that HRV may be useful for rapid detection of airway obstruction, especially in situations where end-tidal CO2 monitoring is not optimal, such as during partial airway obstruction.

Brain-heart interaction in perseverative cognition

The move from the concept of homeostasis to that of allostasis has led reactivity stress research to widen the object of its investigation: from the brief physiological response that occurs when one is facing a stressor to what happens when one is anticipating or recovering from a stressor. A paradigmatic example is represented by perseverative cognition, during which human beings react "as if" they were constantly facing a concrete stressor. The core idea behind this review is that the cognitive inflexibility that characterizes perseverative cognition is reflected in both our body (by increased autonomic nervous system rigidity assessed by heart rate variability; HRV) and our brain (by reduced prefrontal-amygdala functional connectivity). This is a review of studies conducted in different settings (laboratory, daily life), populations (healthy, major depression, generalized anxiety), location (United States, Europe), and age groups (children, adults) that consistently replicated the association between autonomic, subjective, and behavioral measures of cognitive inflexibility during perseverative cognition. Moreover, compelling neuroimaging data suggest that HRV reduction from pre- to post-induction of perseverative cognition is associated with both structural and functional brain abnormalities reflecting impaired prefrontal inhibitory control over subcortical structures (e.g., diminished prefrontal-amygdala functional connectivity). The integration of neuroscience techniques with clinical autonomic research has advanced our understanding of the neurobiology of brain-heart interaction during perseverative cognition, potentially yielding to more effective treatment packages. This is clinically relevant if one considers that perseverative cognition is a pervasive transdiagnostic factor that carries prognostic risk for both psychological and somatic health.

New Frontiers in Heart Rate Variability and Social Coherence Research: Techniques, Technologies, and Implications for Improving Group Dynamics and Outcomes

Concepts embraced by the term coherence have been identified as central to fields such as quantum physics, physiology, and social science. There are different types of coherence, although the term always implies a harmonious relationship, correlations and connections between the various parts of a system. A specific measure derived from heart rate variability (HRV) provides a measure of physiological coherence. Another type of coherence, social coherence, relates to the harmonious alignment between couples or pairs, family units, small groups, or larger organizations in which a network of relationships exists among individuals who share common interests and objectives. A high degree of social coherence is reflected by stable and harmonious relationships, which allows for the efficient flow and utilization of energy and communication required for optimal collective cohesion and action. Social coherence requires that group members are attuned and are emotionally connected with each other, and that the group’s emotional energy is organized and regulated by the group as a whole. A number of studies are reviewed which have explored various types of synchronization in infants, pairs and groups, indicating that feelings of cooperation, trust, compassion and increased prosocial behaviors depends largely on the establishment of a spontaneous synchronization of various physiological rhythms between individuals. This article discusses a new application using HRV monitoring in social coherence research and the importance of physiological synchronization in group developmental processes and dynamics. Building on the extensive body of research showing that providing feedback of HRV coherence level at the individual level can improve self-regulation, we suggest the following hypotheses: (1) providing feedback of individual and collective HRV coherence and the degree of heart rhythm synchronization will increase group coherence, and heart rhythm synchronization among group members. (2) Training in techniques to increase group coherence and heart rhythm synchronization will correlate with increased prosocial behaviors, such as kindness and cooperation among individuals, improved communication, and decreases in social discord and adversarial interactions. (3) Biomagnetic fields produced by the heart may be a primary mechanism in mediating HRV synchronization among group members. Data supporting each of the hypothesis is discussed.

A theoretical and empirical modeling of anxiety integrated with RDoC and temporal dynamics

The newly launched Research Domain Criteria (RDoC) emphasize specific mechanisms over diagnostic categories of psychopathology. In our view, RDoC provides a useful heuristic for mental health disorders, but does not capture the complexity of psychological data when proposed mechanisms are viewed as static entities. However, temporal and complex system dynamics may advance RDoC's utility. By investigating temporal patterns within trajectories and the interaction of complex networks, we propose that dynamic modeling provides comprehensive methods with which to investigate the etiopathology and maintenance of mental health disorders. We examine applications of dynamical systems to periphery physiology, an RDoC construct that has been widely used in psychological science. A review of the literature suggests methodological problems with aggregate and reductive models. We present a dynamical systems modeling of anxiety which suggests avenues for future biomarker research. This model appears congruent with RDoC and recent learning theory.

Manipulation of heart rate variability can modify response to anger-inducing stimuli

Research suggests that heart rate variability (HRV) is a physiological indicator of the flexibility of the autonomic nervous system and can provide an objective measure of an individual's ability to appropriately match emotional responses to environmental demands. The present study investigated whether angry response to emotional stimuli was related to HRV, and whether manipulation of HRV using biofeedback could change the anger response in a healthy adult population. Fifty-eight participants received HRV biofeedback (n = 29) or an active control condition (n = 29). HRV measures included standard deviation of normal-to-normal intervals (SDNN), low-frequency (LF) and high-frequency (HF) power, and was recorded across three sessions: baseline, training, and anger induction. The anger induction procedure resulted in increased subjective experience of anger, as well as physiological changes. The biofeedback group had higher HRV than active controls both during the training session (SDNN and LF HRV) and during anger induction (LF HRV). HRV during anger induction was significantly associated with self-reported emotional response for participants receiving biofeedback but not for active controls. Results provide support for HRV as an index of emotion regulation, specifically anger. Further research is needed to determine whether long-term HRV biofeedback can have a lasting effect on managing anger.

Executive Functioning in Children, Adolescents, and Young Adults with Chronic Kidney Disease

OBJECTIVE

To compare behavior ratings of executive functioning in individuals with chronic kidney disease (CKD), using the Behavior Rating Inventory for Executive Functions (BRIEF), with a typically developing comparison group and to examine the correlation between disease severity and ratings of executive functioning.

METHODS

Participants included 92 individuals with CKD (eGFR < 90 mL/min per 1.73 m), aged 8 to 25 years, recruited from nephrology clinics in both hospital and community settings. The disease severity ranged from CKD Stage II to V. The BRIEF was completed by parents for individuals younger than 18 years of age and the BRIEF-Adult was completed by individuals who were older than 18.

RESULTS

For individuals with CKD younger than 18 years of age, the parent-reported BRIEF revealed significant group differences when compared with controls on the Metacognition Index and the individual scales of Initiate, Working Memory, and Plan/Organize. A large proportion of individuals with CKD were rated as being at-risk for executive dysfunction. For the individuals of 18 years of age and older, there were no significant group differences. The relationship between BRIEF ratings and disease severity was limited to a few scales across both versions of the BRIEF.

CONCLUSION

This study supported the presence of executive dysfunction through a parent report, although the level of impairment was mild and its association with disease severity was related to select executive functions. Few difficulties were reported by older adolescents and young adults with CKD. It will be important for developmental-behavioral pediatricians to be cognizant of the level and pattern of executive function capabilities in their patients with CKD, and possible discrepancies with parent reports, so as to facilitate their management and transition planning.

The impact of cardiac coherence on executive functioning in children with emotional disturbances

OBJECTIVE

We used archival data originally collected using a quasi-experimental design to analyze inhibition, emotional regulation, working memory, and cognitive flexibility before and after an intervention of a coherence training program incorporating heart rate variability biofeedback.

METHOD

Sixty-three participants, ages 7 to 14 years, were involved in the study: 30 in the treatment group and 33 in the control group. Split-plot analysis of variance (SPANOVA) was used to assess the impact of the intervention for the 4 dependent variables.

RESULTS

SPANOVA yielded no significant differences among inhibition, emotional regulation, working memory, and cognitive flexibility in response to the coherence training intervention.

CONCLUSIONS

Future research in this area would benefit from the use of more objective measures of executive functioning. Qualitative assessment of child-reported symptomatology and treatment acceptability on the part of students and staff would also be an area for future research.

Heart Rate Variability: New Perspectives on Physiological Mechanisms, Assessment of Self-regulatory Capacity, and Health risk

Heart rate variability, the change in the time intervals between adjacent heartbeats, is an emergent property of interdependent regulatory systems that operates on different time scales to adapt to environmental and psychological challenges. This article briefly reviews neural regulation of the heart and offers some new perspectives on mechanisms underlying the very low frequency rhythm of heart rate variability. Interpretation of heart rate variability rhythms in the context of health risk and physiological and psychological self-regulatory capacity assessment is discussed. The cardiovascular regulatory centers in the spinal cord and medulla integrate inputs from higher brain centers with afferent cardiovascular system inputs to adjust heart rate and blood pressure via sympathetic and parasympathetic efferent pathways. We also discuss the intrinsic cardiac nervous system and the heart-brain connection pathways, through which afferent information can influence activity in the subcortical, frontocortical, and motor cortex areas. In addition, the use of real-time HRV feedback to increase self-regulatory capacity is reviewed. We conclude that the heart's rhythms are characterized by both complexity and stability over longer time scales that reflect both physiological and psychological functional status of these internal self-regulatory systems.

Heart rate variability biofeedback: Theoretical basis, delivery, and its potential for the treatment of substance use disorders

Heart rate variability biofeedback (HRV BFB) is a biobehavioural clinical intervention that is gaining growing empirical support for the treatment of a number of psychological disorders, several of which are highly comorbid with substance use disorders (SUDs). The present article reviews the autonomic nervous system bases of two key processes implicated in the formation and maintenance of addictive pathology-affect dysregulation and craving-and asks if HRV BFB may be an effective intervention to ameliorate autonomic nervous system dysregulation in these processes, and as such, prove to be an effective intervention for SUDs. A detailed description of HRV BFB and its delivery is provided. Preliminary evidence suggests HRV BFB may be an effective addendum to current first-line SUD treatments, though no firm conclusions can be drawn at this time; more research is needed.

Subliminal versus supraliminal stimuli activate neural responses in anterior cingulate cortex, fusiform gyrus and insula: a meta-analysis of fMRI studies

Background

Non-conscious neural activation may underlie various psychological functions in health and disorder. However, the neural substrates of non-conscious processing have not been entirely elucidated. Examining the differential effects of arousing stimuli that are consciously, versus unconsciously perceived will improve our knowledge of neural circuitry involved in non-conscious perception. Here we conduct preliminary analyses of neural activation in studies that have used both subliminal and supraliminal presentation of the same stimulus.

Methods

We use Activation Likelihood Estimation (ALE) to examine functional Magnetic Resonance Imaging (fMRI) studies that uniquely present the same stimuli subliminally and supraliminally to healthy participants during functional magnetic resonance imaging (fMRI). We included a total of 193 foci from 9 studies representing subliminal stimulation and 315 foci from 10 studies representing supraliminal stimulation.

Results

The anterior cingulate cortex is significantly activated during both subliminal and supraliminal stimulus presentation. Subliminal stimuli are linked to significantly increased activation in the right fusiform gyrus and right insula. Supraliminal stimuli show significantly increased activation in the left rostral anterior cingulate.

Conclusions

Non-conscious processing of arousing stimuli may involve primary visual areas and may also recruit the insula, a brain area involved in eventual interoceptive awareness. The anterior cingulate is perhaps a key brain region for the integration of conscious and non-conscious processing. These preliminary data provide candidate brain regions for further study in to the neural correlates of conscious experience.

Electronic supplementary material

The online version of this article (doi:10.1186/s40359-014-0052-1) contains supplementary material, which is available to authorized users.

Cardiac coherence, self-regulation, autonomic stability, and psychosocial well-being

The ability to alter one’s emotional responses is central to overall well-being and to effectively meeting the demands of life. One of the chief symptoms of events such as trauma, that overwhelm our capacities to successfully handle and adapt to them, is a shift in our internal baseline reference such that there ensues a repetitive activation of the traumatic event. This can result in high vigilance and over-sensitivity to environmental signals which are reflected in inappropriate emotional responses and autonomic nervous system dynamics. In this article we discuss the perspective that one’s ability to self-regulate the quality of feeling and emotion of one’s moment-to-moment experience is intimately tied to our physiology, and the reciprocal interactions among physiological, cognitive, and emotional systems. These interactions form the basis of information processing networks in which communication between systems occurs through the generation and transmission of rhythms and patterns of activity. Our discussion emphasizes the communication pathways between the heart and brain, as well as how these are related to cognitive and emotional function and self-regulatory capacity. We discuss the hypothesis that self-induced positive emotions increase the coherence in bodily processes, which is reflected in the pattern of the heart’s rhythm. This shift in the heart rhythm in turn plays an important role in facilitating higher cognitive functions, creating emotional stability and facilitating states of calm. Over time, this establishes a new inner-baseline reference, a type of implicit memory that organizes perception, feelings, and behavior. Without establishing a new baseline reference, people are at risk of getting “stuck” in familiar, yet unhealthy emotional and behavioral patterns and living their lives through the automatic filters of past familiar or traumatic experience.

A computational physiology approach to personalized treatment models: the beneficial effects of slow breathing on the human cardiovascular system

Heart rate variability biofeedback intervention involves slow breathing at a rate of ∼6 breaths/min (resonance breathing) to maximize respiratory and baroreflex effects on heart period oscillations. This intervention has wide-ranging clinical benefits and is gaining empirical support as an adjunct therapy for biobehavioral disorders, including asthma and depression. Yet, little is known about the system-level cardiovascular changes that occur during resonance breathing or the extent to which individuals differ in cardiovascular benefit. This study used a computational physiology approach to dynamically model the human cardiovascular system at rest and during resonance breathing. Noninvasive measurements of heart period, beat-to-beat systolic and diastolic blood pressure, and respiration period were obtained from 24 healthy young men and women. A model with respiration as input was parameterized to better understand how the cardiovascular processes that control variability in heart period and blood pressure change from rest to resonance breathing. The cost function used in model calibration corresponded to the difference between the experimental data and model outputs. A good match was observed between the data and model outputs (heart period, blood pressure, and corresponding power spectral densities). Significant improvements in several modeled cardiovascular functions (e.g., blood flow to internal organs, sensitivity of the sympathetic component of the baroreflex, ventricular elastance) were observed during resonance breathing. Individual differences in the magnitude and nature of these dynamic responses suggest that computational physiology may be clinically useful for tailoring heart rate variability biofeedback interventions for the needs of individual patients.