A Swedish population-based study to evaluate the usefulness of resting heart rate in the prediction of suicidal behavior among males

INTRODUCTION

Resting heart rate has been distinctly related to both internalizing (high pulse) and externalizing (low pulse) disorders. We aimed to explore the associations between resting heart rate and suicidal behavior (nonfatal suicide attempt [SA] and suicide death [SD]) and evaluate if such associations exist beyond the effects of internalizing/externalizing symptomatology.

METHOD

We used Cox proportional hazards models to evaluate the associations between resting heart rate (age 19) and later SA/SD in 357,290 Swedish men. Models were controlled for internalizing disorders, externalizing disorders, and resilience (the ability to deal with adversity). Co-relative analysis (comparing pairs of different genetic relatedness) was used to control for unmeasured family confounders and improve causal inference.

RESULTS

In baseline models, low resting heart rate was associated with SA (HR = 0.96; 95% CI: 0.95,0.98) and high resting heart rate with SD (HR = 1.04; 95% CI: 1.002,1.07). The association with SA remained after adjustment for all confounders (HR = 0.98). However, the association with SD did not persist after controlling for covariates. Co-relative analysis did not support causal associations.

CONCLUSIONS

Our findings raise interesting etiological questions for the understanding of suicidal behaviors but do not support the usefulness of resting heart rate in suicide prediction.

The moderating effect of resting heart rate variability on the relationship between pain catastrophizing and depressed mood: an empirical study

Previous research indicated that pain catastrophizing-a negative emotional and cognitive response toward actual or anticipated pain-could contribute to pain intensity and could be associated with depressive symptoms not just in chronic pain patients but in healthy population as well. Accumulated evidence suggests that resting heart rate variability (HRV) as a putative proxy of emotion regulation could moderate the association of self-reported pain catastrophizing and depressed mood. In the present cross-sectional study, we investigated these associations in a healthy young adult sample controlling for the effect of trait rumination. Seventy-two participants (58 females, mean age = 22.2 ± 1.79 years ranging from 19 to 28 years old) completed the Pain Catastrophizing Scale, the Zung Self-Rating Depression Scale and the Ruminative Response Scale. Resting HRV was measured by time domain metric of HRV, the root mean square of successive differences (RMSSD). The results showed that the relationship between pain catastrophizing and depressive symptoms is significantly moderated by resting HRV (indexed by lnRMSSD). Specifically, in participants with higher resting HRV there was no significant relationship between the two investigated variables, while in participants with relatively low or medium HRV pain catastrophizing and depressed mood showed significant positive association. The relationship remained significant after controlling for sex, age and trait rumination. These results might indicate that measuring pain catastrophizing and depressive symptoms is warranted in non-clinical samples as well and higher resting HRV could have a buffer or protective role against depressive symptoms.

Self-regulation training for people with knee osteoarthritis: a protocol for a feasibility randomised control trial (MiNT trial)

Introduction

Knee osteoarthritis (OA) is a chronic secondary musculoskeletal pain condition resulting in disability, reduced quality of life, and high societal costs. Pain associated with knee OA is linked to increased sensitivity in sensory, cognitive, and emotional areas of the brain. Self-regulation training targeting brain functioning related to pain experience could reduce pain and its associated disability. Self-regulatory treatments such as mindfulness meditation (MM) and electroencephalography neurofeedback (EEG-NF) training improve clinical outcomes in people with knee OA. A feasibility clinical trial can address factors that could inform the design of the full trial investigating the effectiveness of self-regulation training programmes in people with knee OA. This clinical trial will evaluate the feasibility, safety, acceptability, experience and perceptions of the self-regulatory training programmes.

Methods

The proposed feasibility trial is based on a double-blind (outcome assessor and investigators), three-arm (MM usual care, EEG-NF + usual care and usual care control group) randomised controlled parallel clinical trial. Participants with knee OA will be recruited from the community and healthcare practices. A research assistant (RA) will administer both interventions (20-min sessions, four sessions each week, and 12 sessions over three successive weeks). Feasibility measures (participant recruitment rate, adherence to interventions, retention rate), safety, and acceptability of interventions will be recorded. An RA blinded to the group allocation will record secondary outcomes at baseline, immediately post-intervention (4th week), and 3 months post-intervention. The quantitative outcome measures will be descriptively summarised. The qualitative interviews will evaluate the participants' experiences and perceptions regarding various aspects of the trial, which includes identifying the barriers and facilitators in participating in the trial, evaluating their opinions on the research procedures, such as their preferences for the study site, and determining the level of acceptability of the interventions as potential clinical treatments for managing knee OA. Māori participant perceptions of how assessment and training practices could be acceptable to a Māori worldview will be explored. The interviews will be audio-recorded and analysed thematically.

Discussion

This trial will provide evidence on the feasibility, safety, and acceptability of the MM and EEG-NF training in people with knee OA, thus informing the design of a full randomised clinical control trial.

Pain-related fear among adult patients undergoing open-heart surgery: an interpretative phenomenological analysis

BACKGROUND

One of the sources of anxiety and fear among patients undergoing open-heart surgery is the possibility of experiencing pain, such as sternotomy-related chest pain. Giving them the chance to express their feelings about the potential pain may be effective in reducing their anxiety and may support their coping strategies.

OBJECTIVES

To examine pain-related fear among patients undergoing open-heart surgery and to understand the underlying reasons of their fears.

METHODS

A qualitative interview based on Heidegger's interpretative phenomenological approach was conducted adhering to the COREQ guidelines. Sixteen patients who were undergoing open-heart surgery in the following day were interviewed at the cardiovascular surgery ward of a university hospital. The organization and mapping of the qualitative data was done by using ATLAS.ti 8.0.

RESULTS

The patients who were afraid of experiencing pain after surgery seemed to be more concerned about open-heart surgery itself (such as pain from sternotomy and chest tubes) and the possibility of prolongation of postoperative pain. To cope with these fears, the patients employed a variety of social and self-coping strategies. Trusting the healthcare team, having a high pain tolerance, and having personal thoughts that take precedence over pain-related fear were the key factors explaining not being afraid of experiencing pain.

CONCLUSIONS

This study provides a deeper understanding of the underlying reasons and the needs of patients in controlling their pain-related fears before open-heart surgery. Trusting the healthcare professionals is one of the main factors for patients to control their pain-related fears. To develop a supportive sense of trust and to help patients in controlling their pain-related fears, surgical nurses must dedicate enough time for understanding patients' concerns while planning their nursing care plans. Future studies may focus on exploring the role of nursing interventions and multidisciplinary team approaches on the management of preoperative pain-related fear.

Baseline heart rate variability predicts placebo hypoalgesia in men, but not women

Introduction

Placebo hypoalgesic effects vary greatly across individuals, making them challenging to control for in clinical trials and difficult to use in treatment. We investigated the potential of resting vagally-mediated heart rate variability (vmHRV) to help predict the magnitude of placebo responsiveness.

Methods

In two independent studies (total N = 77), we administered a placebo paradigm after measuring baseline HRV. In Study I, we delivered heat pain to the forearm, on skin patches treated with "real" and "control" cream (identical inactive creams). In Study II, electrical pulses to the forearm were modulated by sham transcutaneous electrical nerve stimulation. We combined data from both studies to evaluate the relationship between vagally-mediated HRV (vmHRV) parameters and the placebo response size, while also assessing sex differences in this relationship.

Results and Discussion

This revealed a positive association between vmHRV and the degree of pain relief, and this effect was driven by men. These results not only reveal new insights into the (sex-specific) mechanisms of placebo hypoalgesia, but also suggest that measuring vmHRV may be helpful in predicting placebo responsiveness. Given that placebo hypoalgesic effects contribute substantially to treatment outcomes, such a non-invasive and easily obtained predictor would be valuable in the context of personalized medicine.

Effects of remote ischemic conditioning on conditioned pain modulation and cardiac autonomic modulation in women with knee osteoarthritis: placebo-controlled randomized clinical trial protocol

BACKGROUND

It is estimated that over 240 million people worldwide have osteoarthritis, which is a major contributor to chronic pain and central changes in pain processing, including endogenous pain modulation. The autonomic nervous system plays a crucial role in the pain regulatory process. One of the main mechanisms of remote ischemic conditioning is neuronal signaling from the preconditioned extremity to the heart. This study aims to analyze the acute effect of remote ischemic conditioning on local pain, conditioned pain modulation, and cardiac autonomic control in women with knee osteoarthritis and to see if there is a correlation between them.

METHODS

Women more than 50 years with knee osteoarthritis diagnosed according to the American College of Rheumatology criteria in the postmenopausal period will be considered eligible. The study will have blind randomization, be placebo-controlled, and be balanced in a 1:1 ratio. The total of 44 participants will be divided into two groups (22 participants per group): (i) remote ischemic conditioning and (ii) placebo remote ischemic conditioning. Protocol consisting of four cycles of total ischemia, followed immediately by four cycles of 5 min of vascular reperfusion, totaling 40 min. The primary outcomes in the protocol are conditioned pain modulation, which has the pressure pain threshold (kgf/cm2) as its primary outcome measure, and cardiac autonomic modulation, which has the indices found in heart rate variability as its primary outcome measure. Comparisons will be performed using generalized linear mixed models fitted to the data. For correlation, the Pearson or Spearman test will be used depending on the normality of the data. All analyses will assume a significance level of p < 0.05.

DISCUSSION

It is believed that the results of this study will present a new perspective on the interaction between the pain processing system and the cardiovascular system; they will provide the professional and the patient with a greater guarantee of cardiovascular safety in the use of the intervention; it will provide knowledge about acute responses and this will allow future chronic intervention strategies that aim to be used in the clinical environment, inserted in the multimodal approach, for the treatment of osteoarthritis of the knee.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05059652. Registered on 30 August 2021. Last update on 28 March 2023.

The autonomic and nociceptive response to acute exercise is impaired in people with knee osteoarthritis

Objectives

An acute bout of exercise typically leads to short term exercise induced hypoalgesia (EIH), but this response is more variable in many chronic pain populations, including knee osteoarthritis (OA) and fibromyalgia (FM). There is evidence of autonomic nervous system (ANS) dysfunction in some chronic pain populations that may contribute to impaired EIH, but this has not been investigated in people with knee OA. The aim of this study was to assess the acute effects of isometric exercise on the nociceptive and autonomic nervous systems in people with knee OA and FM, compared to pain-free controls.

Methods

A cross-sectional study was undertaken with 14 people with knee OA, 13 people with FM, and 15 pain free controls. Across two experimental sessions, baseline recordings and the response of the nociceptive and autonomic nervous systems to a 5-min submaximal isometric contraction of the quadriceps muscle was assessed. The nociceptive system was assessed using pressure pain thresholds at the knee and forearm. The ANS was assessed using high frequency heart rate variability, cardiac pre-ejection period, and electrodermal activity. Outcome measures were obtained before and during (ANS) or immediately after (nociceptive) the acute bout of exercise.

Results

Submaximal isometric exercise led to EIH in the control group. EIH was absent in both chronic pain groups. Both chronic pain groups showed lower vagal activity at rest. Furthermore, people with knee OA demonstrated reduced vagal withdrawal in response to acute isometric exercise compared to controls. Sympathetic reactivity was similar across groups.

Discussion

The findings of reduced tonic vagal activity and reduced autonomic modulation in response to isometric exercise raise the potential of a blunted ability to adapt to acute exercise stress and modulate nociception in people with knee OA. The impairment of EIH in knee OA may, in part, be due to ANS dysfunction.

Emotion regulation and the salience network: a hypothetical integrative model of fibromyalgia

Fibromyalgia is characterized by widespread pain, fatigue, sleep disturbances and other symptoms, and has a substantial socioeconomic impact. Current biomedical and psychosocial treatments are unsatisfactory for many patients, and treatment progress has been hindered by the lack of a clear understanding of the pathogenesis of fibromyalgia. We present here a model of fibromyalgia that integrates current psychosocial and neurophysiological observations. We propose that an imbalance in emotion regulation, reflected by an overactive 'threat' system and underactive 'soothing' system, might keep the 'salience network' (also known as the midcingulo-insular network) in continuous alert mode, and this hyperactivation, in conjunction with other mechanisms, contributes to fibromyalgia. This proposed integrative model, which we term the Fibromyalgia: Imbalance of Threat and Soothing Systems (FITSS) model, should be viewed as a working hypothesis with limited supporting evidence available. We hope, however, that this model will shed new light on existing psychosocial and biological observations, and inspire future research to address the many gaps in our knowledge about fibromyalgia, ultimately stimulating the development of novel therapeutic interventions.

Triad Multisystem Phenotype with High-risk for Developing Temporomandibular Disorders- Characteristics and Potential Pathophysiology Results from the OPPERA Dataset

ABSTRACT

A multisystem phenotype with the Triad of bodily pain, psychological distress, and sleep disturbance was found to have high risk for developing initial onset of painful temporomandibular disorders (TMDs) in the multicenter Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) dataset. In this study, we systemically examined phenotypic characteristics and explored potential pathophysiology in quantitative sensory testing (QST) and autonomic nervous system (ANS) domains in this multisystem Triad phenotype. Secondary analysis was performed on 1199 non-Triad and 154 Triad TMD-free OPPERA enrollees at baseline. Results indicate that prior to developing TMDs, the Triad phenotype demonstrated both orofacial and systemic signs and symptoms that can only be captured through multisystem assessment. In addition, we found significantly lower resting heart rate variability and higher resting heart rate in the Triad phenotype as compared to the non-Triad group. However, pain sensitivity measured by QST was not different between groups. These findings highlight the importance of whole-person multisystem assessment at the stage prior to developing complex pain conditions such as TMDs, and suggest that, in addition to a "tissue damage monitor", pain should be considered in a broader context, such as a component within a "distress monitoring system" at the whole-person level when multisystem issues co-present. Therefore, the presence or absence of multisystem issues may carry critical information when searching for disease mechanisms and developing mechanism-based intervention and prevention strategies for TMDs and related pain conditions. Cardiovascular autonomic function should be further researched when multisystem issues co-present prior to developing TMDs.

Heart Rate Variability and Pain: A Systematic Review

Background and Objective: Heart rate variability (HRV) as an index of the autonomic nervous system appears to be related to reactivity to experimental pain stimuli. HRV could better explain the contributions of sympathetic and parasympathetic activity response to nociceptive stimulation. The aim of this study was to systematically review and synthesize the current evidence on HRV in relation to the experience of pain in experimental tasks. Databases and Data Treatment: Studies indexed in the PubMed, PsycINFO, MEDLINE, WebOfScience, and Scopus databases were reviewed for eligibility. Studies on the autonomic response (i.e., HRV) to experimentally induced pain in healthy adults were included. Different methods of pain induction were considered (e.g., thermal, pressure, and electrical). Data were synthesized considering the association between HRV and both pain induction and subjective measures of pain. Results: Seventy-one studies were included. The results underline significant change in both the sympathetic and parasympathetic autonomic nervous systems during the painful stimulation independent of the pain induction method. The autonomic reaction to pain could be affected by several factors, such as sex, age, body mass index, breathing patterns, the intensity of the stimulation, and the affective state. Moreover, an association between the autonomic nervous system and the subjective experience of pain was found. Higher parasympathetic activity was associated with better self-regulation capacities and, accordingly, a higher pain inhibition capacity. Conclusions: HRV appears to be a helpful marker to evaluate nociceptive response in experimentally induced pain. Future studies are also needed in clinical samples to understand better the interindividual changes of autonomic response due to pain stimuli.

Wearable Devices: Current Status and Opportunities in Pain Assessment and Management

INTRODUCTION

We investigated the possibilities and opportunities for using wearable devices that measure physical activity and physiometric signals in conjunction with ecological momentary assessment (EMA) data to improve the assessment and treatment of pain.

METHODS

We considered studies with cross-sectional and longitudinal designs as well as interventional or observational studies correlating pain scores with measures derived from wearable devices. A search was also performed on studies that investigated physical activity and physiometric signals among patients with pain.

RESULTS

Few studies have assessed the possibility of incorporating wearable devices as objective tools for contextualizing pain and physical function in free-living environments. Of the studies that have been conducted, most focus solely on physical activity and functional outcomes as measured by a wearable accelerometer. Several studies report promising correlations between pain scores and signals derived from wearable devices, objectively measured physical activity, and physical function. In addition, there is a known association between physiologic signals that can be measured by wearable devices and pain, though studies using wearable devices to measure these signals and associate them with pain in free-living environments are limited.

CONCLUSION

There exists a great opportunity to study the complex interplay between physiometric signals, physical function, and pain in a real-time fashion in free-living environments. The literature supports the hypothesis that wearable devices can be used to develop reproducible biosignals that correlate with pain. The combination of wearable devices and EMA will likely lead to the development of clinically meaningful endpoints that will transform how we understand and treat pain patients.

Exploring the relationship between the speed-resolved perfusion of blood flux and HRV following different thermal stimulations using MSE and MFE analyses

Our previous study employed the classic laser Doppler flux (LDF) to explore the complexity of local blood flow signals and their relationship with heart rate variability (HRV). However, microcirculation blood flow is composed of different velocity components. To investigate the complexity of local speed-resolved perfusion and HRV following stimulation with different temperatures in healthy subjects, multiscale entropy (MSE) and multiscale fuzzy entropy (MFE) were used to measure the complexity of local speed-resolved perfusion signals. MSE was also used to evaluate the complexity of HRV. The results indicated that thermal stimulation increased all components of local speed-resolved perfusion and that stimulation with different temperatures resulted in different changes in the complexity area index. However, the same stimulation had no effect on the MSE of HRV. Further research showed that 44°C thermal stimulation resulted in a weak correlation between the composite speed-resolved perfusion and the HRV complexity. The current study provides a new approach for studying the relationship between speed-resolved perfusion signals and cardiac function.

Can a Brief Relaxation Exercise Modulate Placebo or Nocebo Effects in a Visceral Pain Model?

Translational research aiming to elucidate mediators and moderators of placebo and nocebo effects is highly relevant. This experimental study tested effects of a brief progressive muscle relaxation (PMR) exercise, designed to alter psychobiological stress parameters, on the magnitude of placebo and nocebo effects in a standardized psychosocial treatment context. In 120 healthy volunteers (60 men, 60 women), pain expectation, pain intensity, and pain unpleasantness in response to individually-calibrated rectal distensions were measured with visual analog scales during a baseline. Participants were then randomized to exercise PMR (relaxation group: N = 60) or a simple task (control group: N = 60), prior to receiving positive (placebo), negative (nocebo) or neutral suggestions regarding an intravenous administration that was in reality saline in all groups. Identical distensions were repeated (test). State anxiety, salivary cortisol, heart rate, and blood pressure were assessed repeatedly. Data were analyzed using analysis of covariance, planned Bonferroni-corrected group comparisons, as well as exploratory correlational and mediation analyses. Treatment suggestions induced group-specific changes in pain expectation, with significantly reduced expectation in placebo and increased expectation in nocebo groups. PMR had no discernable effect on pain expectation, state anxiety or cortisol, but led to significantly lower heart rate and systolic blood pressure. Relaxation significantly interacted with positive treatment suggestions, which only induced placebo analgesia in relaxed participants. No effects of negative suggestions were found in planned group comparisons, irrespective of relaxation. Exploratory correlation and mediation analyses revealed that pain expectation was a mediator to explain the association between treatment suggestions and pain-related outcomes. Clearly, visceral pain modulation is complex and involves many cognitive, emotional, and possibly neurobiological factors that remain to be fully understood. Our findings suggest that a brief relaxation exercise may facilitate the induction of placebo analgesia by positive when compared to neutral treatment suggestions. They underscore the contribution of relaxation and stress as psychobiological states within the psychosocial treatment context-factors which clearly deserve more attention in translational studies aiming to maximize positive expectancy effects in clinical settings.

The effects of propranolol on heart rate variability and quantitative, mechanistic, pain profiling: a randomized placebo-controlled crossover study

Background and aims

The autonomic nervous system (ANS) is capable of modulating pain. Aberrations in heart rate variability (HRV), reflective of ANS activity, are associated with experimental pain sensitivity, chronic pain, and more recently, pain modulatory mechanisms but the underlying mechanisms are still unclear. HRV is lowered during experimental pain as well as in chronic pain conditions and HRV can be increased by propranolol, which is a non-selective β-blocker. Sensitization of central pain pathways have been observed in several chronic pain conditions and human mechanistic pain biomarkers for these central pain pathways include temporal summation of pain (TSP) and conditioned pain modulation (CPM). The current study aimed to investigate the effect of the β-blocker propranolol, and subsequently assessing the response to standardized, quantitative, mechanistic pain biomarkers.

Methods

In this placebo-controlled, double-blinded, randomized crossover study, 25 healthy male volunteers (mean age 25.6 years) were randomized to receive 40 mg propranolol and 40 mg placebo. Heart rate, blood pressure, and HRV were assessed before and during experimental pain tests. Cuff pressure pain stimulation was used for assessment of pain detection (cPDTs) and pain tolerance (cPTTs) thresholds, TSP, and CPM. Offset analgesia (OA) was assessed using heat stimulation.

Results

Propranolol significantly reduced heart rate (p<0.001), blood pressure (p<0.02) and increased HRV (p<0.01) compared with placebo. No significant differences were found comparing cPDT (p>0.70), cPTT (p>0.93), TSP (p>0.70), OA-effect (p>0.87) or CPM (p>0.65) between propranolol and placebo.

Conclusions

The current study demonstrated that propranolol increased HRV, but did not affect pressure pain sensitivity or any pain facilitatory or modulatory outcomes.

Implications

Analgesic effects of propranolol have been reported in clinical pain populations and the results from the current study could indicate that increased HRV from propranolol is not associated with peripheral and central pain pathways in healthy male subjects.

Negative Affectivity, Depression, and Resting Heart Rate Variability (HRV) as Possible Moderators of Endogenous Pain Modulation in Functional Somatic Syndromes

Background: Several studies have shown that patients with functional somatic syndromes (FSS) have, on average, deficient endogenous pain modulation (EPM), as well as elevated levels of negative affectivity (NA) and high comorbidity with depression and reduced resting heart rate variability (HRV) compared to healthy controls (HC). The goals of this study were (1) to replicate these findings and (2) to investigate the moderating role of NA, depression, and resting HRV in EPM efficiency within a patient group with fibromyalgia and/or chronic fatigue syndrome (CFS). Resting HRV was quantified as the root mean square of successive differences between inter-beat intervals (RMSSD) in rest, a vagally mediated time domain measure of HRV.

Methods: Seventy-eight patients with fibromyalgia and/or CFS and 33 HC completed a counter-irritation paradigm as a measure of EPM efficiency. Participants rated the painfulness of electrocutaneous stimuli (of individually calibrated intensity) on the ankle before (baseline phase), during (counter-irritation phase) and after (recovery phase) the application of a cold pain stimulus on the forearm. A larger reduction in pain in the counter-irritation phase compared to the baseline phase reflects a more efficient EPM.

Results: In contrast to our expectations, there was no difference between pain ratings in the baseline compared to counter-irritation phase for both patients and HC. Therefore, reliable conclusions on the moderating effect of NA, depression, and RMSSD could not be made. Surprisingly, patients reported more pain in the recovery compared to the counter-irritation and baseline phase, while HC did not. This latter effect was more pronounced in patients with comorbid depression, patients who rated the painfulness of the counter-irritation stimulus as high and patients who rated the painfulness of the electrocutaneous stimuli as low. We did not manage to successfully replicate the counter-irritation effect in HC or FSS patients. Therefore, no valid conclusions on the association between RMSSD, depression, NA and EPM efficiency can be drawn from this study. Possible reasons for the lack of the counter-irritation effect are discussed.