Combining top-down and bottom-up interventions targeting the vagus nerve to increase resilience

Mental distress and inflammation in bladder cancer: The nerve makes things less vague

Objectives

This study aimed to explore the interaction between perceived stress, life satisfaction, heart rate variability (HRV), and immune-inflammatory markers in bladder cancer patients. We investigated how HRV moderates the relationship between psychological distress and levels of TNF-α and TGF-β cytokines. We hypothesized that high vagal nerve activity, as indicated by higher HRV, mitigates the impact of perceived stress and life dissatisfaction on inflammation.

Methods

The study included 73 patients with bladder cancer. HRV was determined from a 5-min ECG recording, focusing on the standard deviation of normal-to-normal interbeat intervals (SDNN). Psychological distress was measured using the Perceived Stress Scale (PSS), and life satisfaction was evaluated with the Life Satisfaction Questionnaire (LSQ). Serum concentrations of TNF-α and plasma levels of TGF-β were determined using sandwich ELISA.

Results

We found evidence that HRV modulates the relation between perceived stress and inflammation. In patients with low HRV (SDNN <20 ms), PSS was positively correlated with serum level of TNF-α and negatively with the level of TGF-β, while life satisfaction was positively correlated with TGF-β. These relationships were not significant in patients with high HRV (SDNN ≥20 ms).

Conclusion

Our findings suggest that high vagal activity, as indicated by higher HRV, may mitigate the adverse effects of psychological distress on immune-inflammatory responses in patients with bladder cancer. Stress-related inflammation took place under conditions of low HRV, highlighting the potential role of autonomic regulation in cancer prognosis. Future research should further explore these relationships to develop interventions aimed at improving patient outcomes through stress management and enhanced vagal nerve activity to regulate inflammation in cancer.

The neural mechanisms subserving the adaptiveness of emotion regulation flexibility and its link to depression

Emotion Regulation Flexibility (ERF) is defined as an individual's ability to adaptively respond to changing situations and goals. Deficits in the adaptiveness of ERF have been linked to depression, suggesting a critical relationship between emotional processing and mental health. The objective of the present study was to investigate how variations in situational and goal-related contexts influence the association between ERF adaptiveness and depression. We employed functional magnetic resonance imaging (fMRI) and behavioral tasks to explore this relationship. Participants completed tasks designed to provoke changing situations and changing goals, while fMRI captured neural activity. Our findings revealed a significant negative correlation between depression scores and ERF adaptiveness. Specifically, during changing-situations, activation was observed in temporal and limbic regions, while changing-goals engaged prefrontal and parietal regions. Correlation analyses indicated that the adaptiveness of ERF was supported by distinct neural contributions: the temporoparietal junction (TPJ) in the changing-situations condition and the dorsolateral prefrontal cortex (dlPFC) in the changing-goals condition. Furthermore, the functional coupling between the dlPFC and the ventromedial prefrontal cortex (vmPFC) mediated the relationship between ERF adaptiveness and depression during changing-goals, but not during changing-situations. These findings elucidate the neural mechanisms of ERF adaptiveness and its implications for understanding and addressing depression.

Effects of Electrical Stimulation on Activation of Mirror Neuron Network in Healthy Adults during Motor Execution and Imitation: An fNIRS Study

BACKGROUND

Observation, execution, and imitation of target actions based on mirror neuron network (MNN) have become common physiotherapy strategies. Electrical stimulation (ES) is a common intervention to improve muscle strength and motor control in rehabilitation treatments. It is possible to enhance MNN's activation by combining motor execution (ME) and motor imitation (MI) with ES simultaneously. This study aims to reveal whether ES could impact cortical activation during ME and MI.

METHODS

We recruited healthy individuals and assigned them randomly to the control group (CG) or experiment group (EG). Participants in EG performed ME and MI tasks with ES, while participants in CG performed the same two tasks with sham ES. We utilized functional near-infrared spectroscopy (fNIRS) to detect brain activation of MNN during ME and MI with and without ES, a randomized block design experiment paradigm was designed. Descriptive analysis of oxy-hemoglobin (HbO) and deoxy-hemoglobin (HbR) were used to show the hemoglobin (Hb) concentration changes after different event onsets in both CG and EG, a linear mixed-effects model (LMM) of HbO data was employed to analyze the effect of ES on the activation of MNN.

RESULTS

A total of 102 healthy adults were recruited and 72 participants' data were analysed in the final report. The block averaged Hb data showed that HbO concentration increased and HbR concentration decreased in most MNN regions during ME and MI in both groups. The LMM results showed that ES can significantly improve the activation of inferior frontal gyrus, middle frontal gyrus, and precentral gyrus during MI, the supplementary motor area, inferior parietal lobule, and superior temporal gyri showed increased activation, but without statistical significance. Although the results did not reach statistical significance during ME, ES still showed positive effects on increased overall activations.

CONCLUSIONS

In this study, we present potential novel rehabilitation approaches that combines MNN strategies and low-frequency ES to enhance cortical activation. Our results revealed that ES has potential to increase activation of most MNN brain areas, providing evidence for related rehabilitative interventions and device development.

CLINICAL TRIAL REGISTRATION

This study was registered on the China Clinical Trial Registration Center (identifier: ChiCTR2200064082, registered 26, September 2022, https://www.chictr.org.cn/showproj.html?proj=178285).

Unraveling the temporal interplay of slow-paced breathing and prefrontal transcranial direct current stimulation on cardiac indices of autonomic activity

The neurovisceral integration model proposes that information flows bidirectionally between the brain and the heart via the vagus nerve, indexed by vagally mediated heart rate variability (vmHRV). Voluntary reduction in breathing rate (slow-paced breathing, SPB, 5.5 Breathing Per Minute (BPM)) can enhance vmHRV. Additionally, prefrontal transcranial direct current stimulation (tDCS) can modulate the excitability of the prefrontal region and influence the vagus nerve. However, research on the combination of SPB and prefrontal tDCS to increase vmHRV and other cardiac (heart rate (HR) and blood pressure) and peripheral (skin conductance) indices is scarce. We hypothesized that the combination of 20 min of SPB and prefrontal tDCS would have a greater effect than each intervention in isolation. Hence, 200 participants were divided into four groups: active tDCS with SPB, active tDCS with 15 BPM breathing, sham tDCS with SPB, and sham tDCS with 15 BPM breathing. Regardless of the tDCS condition, the 5.5 BPM group showed a significant increase in vmHRV over 20 minutes and significant decreases in HR at the first and second 5-min epochs of the intervention. Regardless of breathing condition, the active tDCS group exhibited higher HR at the fourth 5-min epoch of the intervention than the sham tDCS group. No other effects were observed. Overall, SPB is a robust technique for increasing vmHRV, whereas prefrontal tDCS may produce effects that counteract those of SPB. More research is necessary to test whether and how SPB and neuromodulation approaches can be combined to improve cardiac vagal tone.

Dose-dependent response of prefrontal transcranial direct current stimulation on the heart rate variability: An electric field modeling study

Transcranial direct current stimulation (tDCS) of the prefrontal cortex (PFC) modulates the autonomic nervous system by activating deeper brain areas via top-down pathway. However, effects on the nervous system are heterogeneous and may depend on the amount of current that penetrates. Therefore, we aimed to investigate the variable effects of tDCS on heart rate variability (HRV), a measure of the functional state of the autonomic nervous system. Using three prefrontal tDCS protocols (1.5, 3 mA and sham), we associated the simulated individual electric field (E-field) magnitude in brain regions of interest with the HRV effects. This was a randomized, double-blinded, sham-controlled and within-subject trial, in which healthy young-adult participants received tDCS sessions separated by 2 weeks. The brain regions of interest were the dorsolateral PFC (DLPFC), anterior cingulate cortex, insula and amygdala. Overall, 37 participants were investigated, corresponding to a total of 111 tDCS sessions. The findings suggested that HRV, measured by root mean squared of successive differences (RMSSD) and high-frequency HRV (HF-HRV), were significantly increased by the 3.0 mA tDCS when compared to sham and 1.5 mA. No difference was found between sham and 1.5 mA. E-field analysis showed that all brain regions of interest were associated with the HRV outcomes. However, this significance was associated with the protocol intensity, rather than inter-individual brain structural variability. To conclude, our results suggest a dose-dependent effect of tDCS for HRV. Therefore, further research is warranted to investigate the optimal current dose to modulate HRV.

Review: Environmental enrichment builds functional capacity and improves resilience as an aspect of positive welfare in production animals

The success of the animal in coping with challenges, and in harnessing opportunities to thrive, is central to its welfare. Functional capacity describes the capacity of molecules, cells, organs, body systems, the whole animal, and its community to buffer against the impacts of environmental perturbations. This buffering capacity determines the ability of the animal to maintain or regain functions in the face of environmental perturbations, which is recognised as resilience. The accuracy of physiological regulation and the maintenance of homeostatic balance underwrite the dynamic stability of outcomes such as biorhythms, feed intake, growth, milk yield, and egg production justifying their assessment as indicators of resilience. This narrative review examines the influence of environmental enrichments, especially during developmental stages in young animals, in building functional capacity and in its subsequent expression as resilience. Experience of enriched environments can build skills and competencies across multiple functional domains including but not limited to behaviour, immunity, and metabolism thereby increasing functional capacity and facilitating resilience within the context of challenges such as husbandry practices, social change, and infection. A quantitative method for measuring the distributed property of functional capacity may improve its assessment. Methods for analysing embedded energy (emergy) in ecosystems may have utility for this goal. We suggest functional capacity provides the common thread that links environmental enrichments with an ability to express resilience and may provide a novel and useful framework for measuring and reporting resilience. We conclude that the development of functional capacity and its subsequent expression as resilience is an aspect of positive animal welfare. The emergence of resilience from system dynamics highlights a need to shift from the study of physical and mental states to the study of physical and mental dynamics to describe the positive dimension of animal welfare.

Vagally-mediated HRV as a marker of trait rumination in healthy individuals? A large cross-sectional analysis

The tendency to ruminate (i.e., repetitive, self-referential, negative thoughts) is a maladaptive form of emotional regulation and represents a transdiagnostic vulnerability factor for stress-related psychopathology. Vagally-mediated heart rate variability (vmHRV) provides a non-invasive, surrogate measure of vagal modulation of the heart, and higher HRV is considered an indicator of susceptibility, or ability to respond to stress. Past research has suggested a link between trait rumination and vmHRV; however, inconsistent results exist in healthy individuals. In this study, we investigated the association between the tendency to ruminate, brooding, and reflection (using the Ruminative Response Scale) with vmHRV measured at baseline in a healthy population using a large cross-sectional dataset (N = 1189, 88% female; mean age = 21.55, ranging from 17 to 48 years old), which was obtained by combining samples of healthy individuals from different studies from our laboratory. The results showed no cross-sectional correlation between vmHRV and trait rumination (confirmed by Bayesian analysis), even after controlling for important confounders such as gender, age, and depressive symptoms. Also, a non-linear relationship was rejected. In summary, based on our results in a large sample of healthy individuals, vmHRV is not a marker of trait rumination (as measured by the Ruminative Response Scale).

Yoga is effective for treating chronic pain in veterans with Gulf War Illness at long-term follow-up

BACKGROUND

Clinical Practice Guidelines for Gulf War Illness (GWI) recommend integrative health approaches such as yoga for relief from symptoms, yet little is known about the long-term efficacy of yoga in reducing symptoms of GWI. Here, we evaluated the long-term efficacy of yoga and cognitive-behavioral therapy (CBT) chronic pain treatment in a randomized controlled trial (RCT) of 75 Veterans (57 men, 42-71 ± 7.1 years of age) with Gulf War Illness (GWI).

METHODS

Participants received either 10 weeks of yoga or 10 weeks of CBT for chronic pain. The primary outcome measures were pain severity, and pain interference (Brief Pain Inventory-Short Form). The secondary outcome measures were fatigue, as indicated by a measure of functional exercise capacity (6-Minute Walk Test), depression, autonomic symptom severity, and quality of life. Piecewise linear mixed models were used to examine study hypotheses.

RESULTS

Compared to the CBT group, yoga was associated with greater reductions in pain severity during the 6-month follow-up period (group × time interaction: b = 0.036, se = 0.014, p = .011). Although we did not find between-group differences in the other primary or secondary outcome measures during follow-up (p's > 0.05), exploratory analyses revealed within-group improvements in pain interference, total pain (an experimental outcome variable which combines pain severity and interference), and fatigue in the yoga group (p's < 0.05) but not in the CBT group.

CONCLUSIONS

This is the first study to report long-term follow-up results of yoga as a treatment for GWI. Our results suggest that yoga may offer long-term efficacy in reducing pain, which is a core symptom of GWI.

TRIAL REGISTRATION

Secondary analyses of ClinicalTrials.gov NCT02378025.

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

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

Perseverative Cognition as a Mediator Between Perceived Stress and Sleep Disturbance: A Structural Equation Modeling Meta-analysis (meta-SEM)

Background

According to the perseverative cognition (PC) hypothesis, the repetitive chronic activation of the cognitive representations of stressors are associated with a concomitant prolonged and sustained physiological stress response, including sleep disruption.

Purpose

We conducted a systematic review and structural equation modeling meta-analysis (meta-SEM) on PC as mediator of the association between perceived stress and subjective sleep disturbance (i.e., difficulties falling asleep or maintaining sleep).

Methods

PubMed, Scopus, Medline, CINAHL, and PsycInfo were searched up to September 2021. To test mediation, only longitudinal studies assessing the predictor (perceived stress) at T0, the mediator (PC) at T1, and the outcome (sleep disturbance) at T2, were eligible.

Results

Findings on 3,733 individuals (k = 8) showed a significant component effect of perceived stress on PC (β = 0.340, p &lt; .001), which in turn was related to sleep disturbance (β = 0.258, p &lt; .001). The direct effect of stress on sleep disturbance was significant (β = 0.133, p &lt; .001). Lastly, the indirect effect between stress and sleep disturbance via PC supported the mediation hypothesis (β = 0.09, 95% CI 0.078–0.100). The mediation path remained significant (β = 0.03, 95% CI 0.020–0.036) after adjusting for baseline sleep disturbance. Further leave-one-out sensitivity and control analyses confirmed that all direct and indirect effects were not driven by any single study included in the meta-analysis, as well as their robustness when controlling for sex and age, respectively.

Conclusions

Overall, results of this meta-analysis indicate that PC may be one of the mechanisms explaining how perceived stressful experiences lead to subjective sleep disturbance.

Effects of voluntary slow breathing on heart rate and heart rate variability: A systematic review and a meta-analysis

Voluntary slow breathing (VSB) is used as a prevention technique to support physical and mental health, given it is suggested to influence the parasympathetic nervous system (PNS). However, to date, no comprehensive quantitative review exists to support or refute this claim. We address this through a systematic review and meta-analysis of the effects of VSB on heart rate variability (HRV). Specifically, we focus on HRV parameters indexing PNS activity regulating cardiac functioning, referred to as vagally-mediated (vm)HRV: (1) during the breathing session (i.e., DURING), (2) immediately after one training session (i.e., IM-AFTER1), as well as (3) after a multi-session intervention (i.e., AFTER-INT). From the 1842 selected abstracts, 223 studies were suitable for inclusion (172 DURING, 16 IM-AFTER1, and 49 AFTER-INT). Results indicate increases in vmHRV with VSB, DURING, IM-AFTER1, and AFTER-INT. Given the involvement of the PNS in a large range of health-related outcomes and conditions, VSB exercises could be advised as a low-tech and low-cost technique to use in prevention and adjunct treatment purposes, with few adverse effects expected.

Does concurrent self-administered transcranial direct current stimulation and attention bias modification training improve symptoms of binge eating disorder? Protocol for the TANDEM feasibility randomized controlled trial

BACKGROUND

Binge eating disorder (BED) is a common and disabling problem associated with impaired cognitive control. Preliminary studies show that brain-directed treatments, including transcranial direct current stimulation (tDCS) and attention bias modification training (ABMT), improve cognitive control and alleviate symptoms of BED. When combined, tDCS may enhance the effects of ABMT, and vice versa, thereby improving treatment outcomes.

METHODS

This protocol describes a feasibility single-blind randomized sham-controlled trial of concurrent self-administered tDCS and ABMT in adults with BED (The TANDEM Trial). Eighty adults with BED will be randomly assigned to one of four groups: ABMT with real or sham self-administered tDCS, ABMT only, or waiting list control. In the treatment arms, participants will complete 10-sessions of their allocated intervention over 2-3 weeks. Outcomes will be assessed at baseline (T0), immediately post treatment (T1), and 6 weeks after end of treatment (T2), and at comparable timepoints for participants in the waitlist control group. Feasibility will be evaluated by assessing recruitment/retention rates and blinding success. Acceptability will be assessed quantitatively via participant ratings and qualitatively via semi-structured interviews. Episodes of binge eating at follow-up will be the primary clinical outcome and rate ratios from Poisson regression will be reported. Secondary outcomes will assess changes in ED and general psychopathology, attention bias toward high calorie foods, and executive function.

DISCUSSION

It is hoped that data from the trial will contribute to the development of neurobiologically informed treatments for BED, provide insights into the potential use of at-home variants of tDCS, and inform the design of future large scale trials.