Virtual Reality Breathing Interventions for Mental Health: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Breathing exercises have been shown to reduce mental health problems among clinical and non-clinical populations. Although virtual reality (VR) breathing interventions are assumed to have potential benefits, it remains unclear whether VR breathing interventions are more effective at improving mental health than non-VR breathing interventions. We conducted a systematic literature search in six electronic databases (Web of Science, PsycINFO, Embase, Cochrane Central Register of Controlled Trials, Scopus, and PubMed) from inception to 30th September, 2022. We included randomized controlled trials in adults evaluating effects of VR compared to non-VR breathing interventions on primary outcomes of mental health (stress, anxiety and mood), and secondary outcomes of physiological stress measures (e.g., heart rate (HR), heart rate variability (HRV)). Within these selected studies, we explored differences in likeability and future use between VR and non-VR breathing interventions. 2.848 records were identified of which 65 full-text articles were assessed. Six RCTs were included, of which five were suitable for meta-analyses. Comparing VR to non-VR breathing interventions, there were no significant differences in overall mental health, stress, anxiety or mood, nor in HR or HRV. There was no evidence that participants liked VR breathing interventions more than non-VR, nor would use them more in the future. These results suggest that there is no evidence that VR breathing interventions are more effective than non-VR in improving mental health outcomes, HR, HRV. Further research is required to determine whether there may be advantages to longer-term VR-implementation and practice, and explore possible mechanisms.

Expectation and dyspnoea: the neurobiological basis of respiratory nocebo effects.

Cues such as odours that do not per se evoke bronchoconstriction can become triggers of asthma exacerbations. Despite its clinical significance, the neural basis of this respiratory nocebo effect is unknown.We investigated this effect in a functional magnetic resonance imaging (fMRI) study involving 36 healthy volunteers. The experiment consisted of an experience phase in which volunteers experienced dyspnoea while being exposed to an odorous gas ("Histarinol"). Volunteers were told that Histarinol induces dyspnoea by bronchoconstriction. This was compared with another odorous gas which did not evoke dyspnoea. Dyspnoea was actually induced by a concealed, resistive load inserted into the breathing system. In a second, expectation phase, Histarinol and the control gas were both followed by an identical, very mild load. Respiration parameters were continuously recorded and participants rated dyspnoea intensity after each trial.Dyspnoea ratings were significantly higher in Histarinol compared with control conditions, both in the experience and in the expectation phase, despite identical physical resistance in the expectation phase. Insula fMRI signal matched the actual load, i.e. a significant difference between Histarinol and control in the experience phase, but no difference in the expectation phase. The periaqueductal gray showed a significantly higher fMRI signal during the expectation of dyspnoea. Finally, Histarinol-related deactivations during the expectation phase in the rostral anterior cingulate cortex mirrored similar responses for nocebo effects in pain.These findings highlight the neural basis of expectation effects associated with dyspnoea, which has important consequences for our understanding of the perception of respiratory symptoms.

Adaptive and maladaptive emotion processing and regulation, and the case of alexithymia.

In this conceptual review, we discuss models of emotion and its regulation and identify a spectrum of processes that characterise adaptive adjustment to the affective environment. We describe a dynamic-phasic model of emotion processing and regulation, focusing on five stages: anticipation, response, recovery, habituation and rest as part of a cascade of responses to emotional challenges, as these become progressively expected, proximal, chronic or repeated. We argue for the need to investigate beyond simple reactivity to emotional stimuli, in order to understand mental and physical health conditions where emotional dysregulation plays a role. We propose that a hallmark of an effective and adaptive emotion regulation system is its flexibility, in the service of life goals and values. Consistent with McEwen's model (1998, Stress, adaptation, and disease: Allostasis and allostatic load. Annals of the New York Academy of Sciences, 840(1), 33-44), inflexible emotion regulation can lead to increased allostatic load, from frequent stress, inadequate reactivity, failed shutdown and habituation, which may result in physical and mental illness. Alexithymia exemplifies inflexible emotion regulation, with dysfunctions potentially across all stages of emotion processing, both psychologically and physiologically. These maladaptive processes and their consequence on allostatic load potentially explain the association between alexithymia and physical and mental illness.

Respiratory Changes in Response to Cognitive Load: A Systematic Review.

When people focus attention or carry out a demanding task, their breathing changes. But which parameters of respiration vary exactly and can respiration reliably be used as an index of cognitive load? These questions are addressed in the present systematic review of empirical studies investigating respiratory behavior in response to cognitive load. Most reviewed studies were restricted to time and volume parameters while less established, yet meaningful parameters such as respiratory variability have rarely been investigated. The available results show that respiratory behavior generally reflects cognitive processing and that distinct parameters differ in sensitivity: While mentally demanding episodes are clearly marked by faster breathing and higher minute ventilation, respiratory amplitude appears to remain rather stable. The present findings further indicate that total variability in respiratory rate is not systematically affected by cognitive load whereas the correlated fraction decreases. In addition, we found that cognitive load may lead to overbreathing as indicated by decreased end-tidal CO2 but is also accompanied by elevated oxygen consumption and CO2 release. However, additional research is needed to validate the findings on respiratory variability and gas exchange measures. We conclude by outlining recommendations for future research to increase the current understanding of respiration under cognitive load.

The role of respiratory measures to assess mental load in pilot selection.

While cardiovascular measures have a long tradition of being used to determine operator load, responsiveness of the respiratory system to mental load has rarely been investigated. In this study, we assessed basic and variability measures of respiration rate (RR), partial pressure of end-tidal carbon dioxide (petCO2) as well as performance measures in 63 male pilot candidates during completion of a complex cognitive task and subsequent recovery. Mental load was associated with an increase in RR and a decrease in respiratory variability. A significant decrease was also found for petCO2. RR and respiratory variability showed partial and complete effects of recovery, respectively, whereas petCO2 did not return to baseline level. Overall, a good performance was related to a stronger reactivity in RR. Our findings suggest that respiratory parameters would be a useful supplement to common measures for the assessment of mental load in pilot selection. Practitioner Summary: Respiratory measures are a promising yet poorly investigated approach to monitor operator load. For pilot selection, we assessed respiration in response to multitasking in 63 candidates. Task-related changes as well as covariation with performance strongly support the consideration of respiratory parameters when evaluating reactivity to mental load.

Inhalation/Exhalation ratio modulates the effect of slow breathing on heart rate variability and relaxation.

Slow breathing is widely applied to improve symptoms of hyperarousal, but it is unknown whether its beneficial effects relate to the reduction in respiration rate per se, or, to a lower inhalation/exhalation (i/e) ratio. The present study examined the effects of four ventilatory patterns on heart rate variability and self-reported dimensions of relaxation. Thirty participants were instructed to breathe at 6 or 12 breaths/min, and with an i/e ratio of 0.42 or 2.33. Participants reported increased relaxation, stress reduction, mindfulness and positive energy when breathing with the low compared to the high i/e ratio. A lower compared to a higher respiration rate was associated only with an increased score on positive energy. A low i/e ratio was also associated with more power in the high frequency component of heart rate variability, but only for the slow breathing pattern. Our results show that i/e ratio is an important modulator for the autonomic and subjective effects of instructed ventilatory patterns.

The association between pain-related psychological variables and postural control in low back pain: A systematic review and meta-analysis.

BACKGROUND: Alterations in postural control have been found in individuals with low back pain (LBP), particularly during challenging postural tasks. Moreover, higher levels of negative pain-related psychological variables are associated with increased trunk muscle activity, reduced spinal movement, and worse maximal physical performance in individuals with LBP. RESEARCH QUESTION: Are pain-related psychological variables associated with postural control during static bipedal standing tasks in individuals with LBP? METHODS: A systematic review and meta-analysis were conducted. Pubmed, Web of Science, and PsycINFO were searched until March 2023. Studies were included if they evaluated postural control during static bipedal standing in individuals with LBP by measuring center of pressure (CoP) variables, and reported at least one pain-related psychological variable. Correlation coefficients between pain-related psychological variables and CoP variables were extracted. Study quality was assessed with the "Quality In Prognosis Studies" tool (QUIPS). Random-effect models were used to calculate pooled correlation coefficients for different postural tasks. Sub-analyses were performed for positional or dynamic CoP variables. Certainty of evidence was assessed with an adjusted "Grading of Recommendations, Assessment, Development, and Evaluations" tool (GRADE). The protocol was registered on PROSPERO (CRD42021241739). RESULTS: Sixteen studies (n = 723 participants) were included. Pain-related fear (16 studies) and pain catastrophizing (three studies) were the only reported pain-related psychological variables. Both pain-related fear (-0.04 < pooled r < 0.14) and pain catastrophizing (0.28 < pooled r < 0.29) were weakly associated with CoP variables during different postural tasks. For all associations, the certainty of evidence was very low. SIGNIFICANCE: Pain-related fear and pain catastrophizing are only weakly associated with postural control during static bipedal standing in individuals with LBP, regardless of postural task difficulty. Certainty of evidence is very low thus it is conceivable that future studies accounting for current study limitations might reveal different findings.

Testing emotional response coherence assumptions: Comparing emotional versus non-emotional states.

Although central to theories of emotion, emotional response coherence, that is, coordination among various emotion response systems, has received inconsistent empirical support. This study tests a basic assumption of response coherence, that is, that it characterizes emotional states defining their beginning and end. To do so, we (a) compare response coherence between emotional versus non-emotional states and (b) examine how emotional coherence changes over time, before, during, and after an emotional episode. Seventy-nine participants viewed neutral, pleasant, and unpleasant film clips and rated continuously how pleasant they felt (experience) before (anticipation), during, and after (recovery) each clip. Autonomic physiological arousal responses (skin conductance level, heart rate; physiology) and facial expressions (corrugator, zygomatic activity; expression) were recorded. Within-person cross-correlations between all emotional response pairs were calculated for each phase. Analyses comparing coherence during emotional versus neutral film viewing showed that only experience-expression coherence was higher for emotional versus neutral films, indicating specificity for emotional states. Examining coherence across phases indicated that coherence increased from anticipation to emotional film viewing, as expected, for experience-expression and experience-physiology pairs (SCL only). Of those pairs, increased coherence returned to baseline during recovery, as theoretically assumed, only for experience-corrugator activity coherence. Current findings provide empirical support for theoretical views of response coherence as a defining feature of emotional episodes, but mostly for the coherence between experience and facial expressions. Further research needs to investigate the role of sympathetic arousal indices, as well as the role of response coherence in emotional recovery.

Categorical interoception: the role of disease context and individual differences in habitual symptom reporting.

OBJECTIVE: Symptom reports correspond less to physiological dysfunction in persons with high levels of symptoms in daily life and in patients with functional somatic symptoms, suggesting poor symptom perception. In this study, we investigated whether interoception was impacted by the meaning of the context and by habitual symptom reporting. METHODS: Eight inspiratory resistances that were equidistant in intensity were administered to healthy women (N = 124) varying in habitual symptom reporting. One group was asked to categorise them as benign sensations vs. as bodily symptoms that could suggest a disease (disease context group). Another group was asked to categorise them as low- vs. high-intensity sensations (neutral context group). MAIN OUTCOME: Perceived differences in intensity within- vs. between-category and unpleasantness, categorisation threshold, and the reliability of categorising each stimulus were examined in relation to context (disease, neutral) and symptom reporting levels in daily life. RESULTS: Context (neutral vs. disease) impacted intensity and unpleasantness perception. Processing of respiratory interoceptive stimulation was more detailed, elaborate, and cautious when categorising stimuli as signalling health or disease vs. as low- or high-intensity. Individual differences in habitual symptoms had no effect. CONCLUSION: The pattern of results suggests that these categorisation effects indicate flexible, context-sensitive interoceptive processing, which may characterise healthy individuals.

A novel self-report scale of interoception: the three-domain interoceptive sensations questionnaire (THISQ).

OBJECTIVES: The self-reported perception of bodily sensations is assumed predictive for health and disease. Existing questionnaires mostly focus on aversive sensations, and associated emotions and cognitions, which potentially confounds associations between interoception and illness. Therefore, we developed the Three-domain Interoceptive Sensations Questionnaire (THISQ), assessing self-reported perception of neutral respiratory, cardiac, and gastroesophageal sensations. DESIGN: Using cross-sectional surveys, we developed and validated the THISQ. MAIN OUTCOME MEASURES: In Sample 1 (n = 357), a pool of 28 Dutch items was subjected to exploratory factor analysis. Eighteen items with a primary factor loading >.40 were retained for confirmatory factor analysis in Sample 2 (n = 374) and Sample 3 (n = 484) for the validation of the Dutch and English questionnaire, respectively. RESULTS: Analyses supported the 3-factor solution: cardiorespiratory activation, cardiorespiratory deactivation, and gastroesophageal sensations. Scales showed acceptable to good internal consistency. Convergent validity was confirmed by significant medium associations between THISQ scores and other self-report measures of interoception. Divergent validity was supported by non-significant or small associations with measures of negative affectivity and symptom-related anxiety. CONCLUSION: Our findings suggest that the Dutch and English THISQs are valid and reliable self-report measures of interoception, which could advance our understanding of interoceptive processes in health and disease.Supplemental data for this article is available online at https://doi.org/10.1080/08870446.2021.2009479 .

Respiratory psychophysiology and COVID-19: A research agenda.

After multiple waves of the COVID-19 pandemic, it has become clear that the impact of SARS-CoV-2 will carry on for years to come. Acutely infected patients show a broad range of disease severity, depending on virus variant, vaccination status, age and the presence of underlying medical and physical conditions, including obesity. Additionally, a large number of patients who have been infected with the virus present with post-COVID syndrome. In September 2020, the International Society for the Advancement of Respiratory Psychophysiology organized a virtual interest meeting on 'Respiratory research in the age of COVID-19', which aimed to discuss how research in respiratory psychophysiology could contribute to a better understanding of psychophysiological interactions in COVID-19. In the resulting current paper, we propose an interdisciplinary research agenda discussing selected research questions on acute and long-term neurobiological, physiological and psychological outcomes and mechanisms related to respiration and the airways in COVID-19, as well as research questions on comorbidity and potential treatment options, such as physical rehabilitation.

Imposing respiratory variability patterns.

To ensure respiratory stability and flexibility, healthy breathing shows balanced variability consisting of considerable correlated variability (parameters of each breath are correlated to parameters of adjoining breaths) and some random variability. Sighing resets this balance when respiration lacks variability or becomes excessively irregular. The present study aimed to investigate the effect of imposed patterns of breathing variability on sighing and self-reported (dis)comfort. Spontaneous breathing was compared to imposed non-variable, correlated and random breathing. Results show that executing imposed breathing is difficult, demanding, and induces tension. Sigh occurrence following spontaneous and imposed breathing patterns could be predicted by self-reported discomfort and increased random variability. However, including non-variable, correlated and random breathing patterns only, the effects of self-reported discomfort on sigh occurrence override the effects of altered breathing variability.

The psychophysiology of the sigh: II: The sigh from the psychological perspective.

A sigh is a distinct respiratory behavior with specific psychophysiological roles. In two accompanying reviews we will discuss the physiological and psychological functions of the sigh. The present review will focus on the psychological functions of the sigh. We discuss the regulatory effects of a sigh, and argue how these effects may become maladaptive when sighs occur excessively. The adaptive role of a sigh is discussed in the context of regulation of psychophysiological states. We propose that sighs facilitate transitions from one psychophysiological state to the next, and this way contribute to psychophysiological flexibility, via a hypothesized resetting mechanism. We discuss how a sigh resets respiration, by controlling mechanical and metabolic properties of respiration associated with respiratory symptoms. Next, we elaborate on a sigh resetting emotional states by facilitating emotional transitions. We attempt to explain the adaptive and maladaptive functions of a sigh in the framework of stochastic resonance, in which we propose occasional, spontaneous sighs to be noise contributing to psychophysiological regulation, while excessive sighs result in psychophysiological dysregulation. In this context, we discuss how sighs can contribute to therapeutic interventions, either by increasing sighs to improve regulation in case of a lack of sighing, or by decreasing sighs to restore regulation in case of excessive sighing. Finally, a research agenda on the psychology of sighs is presented.

The psychophysiology of the sigh: I: The sigh from the physiological perspective.

Breathing is composed of multiple, distinct behaviors that are bidirectionally regulated through autonomic and voluntary mechanisms. One behavioral component is the sigh, which serves distinct physiological and psychological roles. In two accompanying reviews we will discuss these roles. The present review focuses on the physiological function, where sighs play a critical role in controlling lung compliance by preventing the collapse of alveoli. Implicated in the generation of sighs and normal breathing is the preBötzinger Complex, a rhythmogenic network in the medulla. Although sighs and normal inspiration are generated within the same network, they show distinct temporal characteristics. While sighs occur every few minutes, normal breathing is generated in the range of seconds. Both are differentiated by distinct modulatory and synaptic mechanisms, and recent evidence indicates that these mechanisms are regulated by inputs from different regions of the brain. An important modulator of sighs is hypoxia, implicating sighs in the arousal response.

The sigh and related behaviors.

Breathing is a critical, complex, and highly integrated behavior. Normal rhythmic breathing, also referred to as eupnea, is interspersed with different breathing related behaviors. Sighing is one of such behaviors, essential for maintaining effective gas exchange by preventing the gradual collapse of alveoli in the lungs, known as atelectasis. Critical for the generation of both sighing and eupneic breathing is a region of the medulla known as the preBötzinger Complex (preBötC). Efforts are underway to identify the cellular pathways that link sighing as well as sneezing, yawning, and hiccupping with other brain regions to better understand how they are integrated and regulated in the context of other behaviors including chemosensation, olfaction, and cognition. Unraveling these interactions may provide important insights into the diverse roles of these behaviors in the initiation of arousal, stimulation of vigilance, and the relay of certain behavioral states. This chapter focuses primarily on the function of the sigh, how it is locally generated within the preBötC, and what the functional implications are for a potential link between sighing and cognitive regulation. Furthermore, we discuss recent insights gained into the pathways and mechanisms that control yawning, sneezing, and hiccupping.

Bottom-Up and Cognitive Top-Down Emotion Regulation: Experiential Emotion Regulation and Cognitive Reappraisal on Stress Relief and Follow-Up Sleep Physiology.

Emotional stress throughout the day is known to affect objective sleep physiology and subjective sleep quality. In the interplay between emotions and sleep, emotion regulation plays a critical role in the recovery from stressful, emotional events and subsequent sleep. While the effects of top-down emotion regulation strategies such as cognitive reappraisal on sleep have been studied before, the impact of bottom-up emotion regulation strategies such as experiential emotion regulation is understudied. Cognitive reappraisal reflects the cognitive reinterpretation of the meaning of a stressful event, while experiential emotion regulation involves an active, non-intervening, accepting, open and welcoming approach of acknowledging awareness of raw sensory affective experiences or 'experiential awareness' in a first phase and expression in a second phase. The present study aims to investigate the effects of experiential emotion regulation and cognitive reappraisal on the recovery from pre-sleep emotional stress measured by (1) negative affect and (2) sleep structure. Sleep of forty-three healthy Dutch-speaking participants (22 females, 21 males) has been assessed using EEG polysomnography. Stress was triggered using a pre-sleep emotional failure induction, after which emotion regulation by experiential emotion regulation versus cognitive reappraisal versus control was induced twice. The control condition consisted of the reallocation of attention towards the neutral aspects of the emotional event. The results indicated that recovery from negative affect of the failure experience after single or repeated deployment of experiential emotion regulation and cognitive reappraisal was not significantly different from the control condition. Moreover, after repeated deployment, sleep physiology did not significantly differ between experiential emotion regulation, cognitive reappraisal, and the control condition in the impact of the regulation of the failure experience. The implications of the distinctive impact of experiential emotion regulation and cognitive reappraisal on both the pre-sleep emotional experience and follow-up sleep physiology are discussed.

Instantaneous changes in heart rate regulation due to mental load in simulated office work.

The cardiac regulation effects of a mental task added to regular office work are described. More insight into the time evolution during the different tasks is created by using time-frequency analysis (TFA). Continuous wavelet transformation was applied to create time series of instantaneous power and frequency in specified frequency bands (LF 0.04-0.15 Hz; HF 0.15-0.4 Hz), in addition to the traditional linear heart rate variability (HRV) parameters. In a laboratory environment, 43 subjects underwent a protocol with three active conditions: a clicking task with low mental load and a clicking task with high mental load (mental arithmetic) performed twice, each followed by a rest condition. The heart rate and measures related to vagal modulation could differentiate the active conditions from the rest condition, meaning that HRV is sensitive to any change in mental or physical state. Differences between physical and mental stress were observed and a higher load in the combined task was observed. Mental stress decreased HF power and caused a shift toward a higher instantaneous frequency in the HF band. TFA revealed habituation to the mental load within the task (after 3 min) and between the two tasks with mental load. In conclusion, the use of TFA in this type of analysis is important as it reveals extra information. The addition of a mental load to a physical task elicited further effect on HRV parameters related to autonomic cardiac modulation.

The respiratory occlusion discrimination task: A new paradigm to measure respiratory interoceptive accuracy.

Interoception, or the sense of the internal state of the body, is hypothesized to be essential for a wide range of psychobiological processes and the development and perpetuation of several (mental) health problems. However, the study of interoceptive accuracy, the objectively measured capacity to detect or discriminate conscious bodily signals, has been hampered by the use of tasks with questionable construct validity and is often limited to studying interoception solely in the cardiac domain. We developed a novel task to measure interoceptive accuracy in the respiratory domain, the respiratory occlusion discrimination (ROD) task. In this task, interoceptive accuracy is defined as an individual's ability to detect small differences in lengths of short respiratory occlusions, assessed by means of an adaptive staircase procedure. This article describes a validation study (N = 97) aimed at investigating the internal consistency, test-retest reliability, and discriminant validity of the ROD task. The average just noticeable difference of lengths of respiratory occlusion was 74.22 ms, with large inter-individual variability (SD = 37.1 ms). The results of the validation study indicate acceptable internal consistency (Cronbach's alpha = 0.70), 1-week test-retest reliability (r = 0.53), and discriminant validity, as indicated by a lack of correlation between the ROD task and an auditory discrimination task with identical design (r = 0.18), and a weak correlation with breathing behavior (r = -0.27). The ROD task is a promising novel paradigm to study interoceptive accuracy and its role in various psychobiological processes and disorders.

Sighs can become learned behaviors via operant learning.

Sighs have important physiological and psychological regulatory functions. These rewarding effects of a sigh potentially reinforce sighing in situations that require physiological and/or psychological regulation. The present study aimed to investigate whether sighs can become learned behaviors via operant learning. In two studies, we manipulated the effect of spontaneous sighs in response to dyspnea relief, by either punishing a sigh by the onset of dyspnea, or not punishing a sigh by continued dyspnea relief. Results show that sigh rates in response to cues predicting the punishment of sighs are 1.20-1.28 times lower than sigh rates in response to cues predicting no punishment of sighs. These findings suggest that sighs can become learned behaviors via operant learning, contributing to both maladaptive sighing, potentially leading to respiratory dysregulation and respiratory complaints, and to adaptive sighing. Furthermore, these findings suggest new clinical practices to increase and decrease sigh rates during breathing training.