Affective traits, states, and breathlessness

Conditioned fear selectively increases the perception and neural processing of respiratory stimuli relative to somatosensory stimuli

Interoception is crucial to the experience of bodily complaints in chronic conditions. Fear can distort the perception of sensations like breathlessness and pain, yet few studies investigated the effects of conditioned fear on both self-report and neural processing of these sensations. In the current study, we conditioned fear of neutral female faces in healthy adults, pairing certain faces (CS+) with an aversive scream. In Experiment 1, we delivered paired inspiratory occlusions during the viewing of the faces. We collected self-reported intensity and unpleasantness of occlusions, and measured N1 and P2 amplitudes of the respiratory-related evoked potential (RREP) in the electroencephalogram, as well as neural gating (the ratio of N1 response to the second over the first occlusion, S2/S1). Skin conductance and self-reported fear increased in response to CS+ faces, and perception of occlusions increased during fear conditioning (FC) relative to baseline, with higher unpleasantness and RREP amplitudes during CS+ relative to CS- trials. We found no effects on neural gating. In Experiment 2, we used the same FC protocol, and delivered paired electrocutaneous pulses during the viewing of the faces. We measured intensity/unpleasantness, fear, N1/P2 amplitudes of the somatosensory evoked potential (SEP), and neural gating. While skin conductance and fear increased, no perceptual effects were found. Unexpectedly, SEP amplitudes decreased and neural gating increased during FC, likely due to habituation. The current results indicate that FC increases the perception and neural processing of respiratory stimuli specifically, consistent with previous literature on respiratory psychophysiology and fearful states.

Affect and post-COVID-19 symptoms in daily life: An exploratory experience sampling study

Insight into the daily life experiences of patients with post-COVID-19 syndrome is lacking. The current study explored temporal fluctuations of and associations between positive and negative affect and symptoms throughout the day in previously hospitalised post-COVID-19 patients using an experience sampling methodology. Ten participants (age: median = 60, interquartile range = 9 years; 50% women; 80% ≥1 comorbidity; 8-12 months since hospital discharge) filled out brief online questionnaires, six times a day for 14 consecutive days. Positive and negative affect, and self-reported symptoms (physical and mental fatigue, cognitive functioning, dyspnoea, and pain) were assessed in real-time. Primarily, graphs were analysed to assess the individual longitudinal courses of and (concurrent and time-lagged) associations between affect and symptoms. Secondly, correlations or multilevel linear regression models were used to support these interpretations. Visual assessment showed limited temporal fluctuation in affect and symptoms. All symptoms appeared to associate positively with each other (correlations between .26 and .85). Positive affect was associated with lower symptoms severity (β's between -.28 and -.67), and negative affect with higher symptoms severity (β's between .24 and .66). Time-lagged analyses showed that-adjusted for residual symptom severity of prior measurements-both types of affect predicted symptom severity two hours later (β's between -.09 and -.31 for positive affect; between .09 and .28 for negative affect). These findings suggest that positive and negative affect may play important roles in post-COVID-19 symptom experience and temporal fluctuation.

Neural oscillatory markers of respiratory sensory gating in human cortices

BACKGROUND

Human respiratory sensory gating is a neural process associated with inhibiting the cortical processing of repetitive respiratory mechanical stimuli. While this gating is typically examined in the time domain, the neural oscillatory dynamics, which could offer supplementary insights into respiratory sensory gating, remain unknown. The purpose of the present study was to investigate central neural gating of respiratory sensation using both time- and frequency-domain analyses.

METHODS

A total of 37 healthy adults participated in this study. Two transient inspiratory occlusions were presented within one inspiration, while responses in the electroencephalogram (EEG) were recorded. N1 amplitudes and oscillatory activities to the first stimulus (S1) and the second stimulus (S2) were measured. The perceived level of breathlessness and level of unpleasantness elicited by the occlusions were measured after the experiment.

RESULTS

As expected, the N1 peak amplitude to the S1 was significantly larger than to the S2. The averaged respiratory sensory gating S2/S1 ratio for the N1 peak amplitude was 0.71. For both the evoked- and induced-oscillations, time-frequency analysis showed higher theta activations in response to S1 relative to S2. A positive correlation was observed between the perceived unpleasantness and induced theta power.

CONCLUSIONS

Our results suggest that theta oscillations, evoked as well as induced, reflect the "gating" of respiratory sensation. Theta oscillation, particularly theta-induced power, may be indicative of the emotional processing of respiratory mechanosensation. The findings of this study serve as a foundation for future investigations into the underlying mechanisms of respiratory sensory gating, particularly in patient populations.

A Systematic Review of Breathing Exercise Interventions: An Integrative Complementary Approach for Anxiety and Stress in Adult Populations

Aim: Nurses are well-qualified to deliver integrative complementary therapy interventions, a holistic approach to assist individuals experiencing anxiety and stress. Self-regulated, controlled breathing exercises (a clinical approach) are reported to decrease anxiety and increase stress tolerance. The aim of this systematic review was to evaluate the effectiveness of breathing exercise interventions on the psychological and physiologic outcomes of anxiety and stress among adults and assess the state of the science in the post-COVID-19 population. Methods: A systematic review was conducted, and four scientific databases were searched: PubMed, CINAHL, EMBASE, and Web of Science. Inclusion criteria included: (1) peer-reviewed studies, (2) adults over 18, (3) breathing exercise interventions, and (4) anxiety or stress as outcomes. Results: Out of 309 studies identified, 19 were included. Twelve reported significant improvements in anxiety and nine reported significant improvements in stress following varying breathing exercise interventions (p < .05). No adverse events were reported. Conclusions: Breathing exercises were found to be effective in reducing anxiety and stress in adults, however, there continues to be limited evidence that includes large randomized controlled trials. Breathing exercises are a holistic care approach that can be safely implemented by nurses to decrease symptomatology among adults, including the post-COVID population.

The effect of unpredictability on the perception of breathlessness: a narrative review

Breathlessness is an aversive bodily sensation impacting millions of people worldwide. It is often highly detrimental for patients and can lead to profound distress and suffering. Notably, unpredictable breathlessness episodes are often reported as being more severe and unpleasant than predictable episodes, but the underlying reasons have not yet been firmly established in experimental studies. This review aimed to summarize the available empirical evidence about the perception of unpredictable breathlessness in the adult population. Specifically, we examined: (1) effects of unpredictable relative to predictable episodes of breathlessness on their perceived intensity and unpleasantness, (2) potentially associated neural and psychophysiological correlates, (3) potentially related factors such as state and trait negative affectivity. Nine studies were identified and integrated in this review, all of them conducted in healthy adult participants. The main finding across studies suggested that unpredictable compared to predictable, breathlessness elicits more frequently states of high fear and distress, which may contribute to amplify the perception of unpredictable breathlessness, especially its unpleasantness. Trait negative affectivity did not seem to directly affect the perception of unpredictable breathlessness. However, it seemed to reinforce state fear and anxiety, hence possible indirect modulatory pathways through these affective states. Studies investigating neural correlates of breathlessness perception and psychophysiological measures did not show clear associations with unpredictability. We discuss the implication of these results for future research and clinical applications, which necessitate further investigations, especially in clinical samples suffering from breathlessness.

Dyspnea induced by inspiratory loading limits dual-tasking in healthy young adults

OBJECTIVES

Dyspnea is a common and multidimensional experience of healthy adults and those with respiratory disorders. Due to its neural processing, it may limit or interfere with cognition, which may be examined with a dual-task paradigm. The aim of this study was to compare single-task performance of Stroop Colour and Word Test (SCWT) or inspiratory threshold loading (ITL) to their combined dual-task performance. Secondly, whether mood was related to dyspnea or cognitive performance was also evaluated.

MATERIALS & METHODS

A virtual pre-post design examined single (SCWT and ITL) and dual-task (SCWT+ITL) performance. For ITL, a Threshold Trainer™ was used to elicit a "somewhat severe" rating of dyspnea. The SCWT required participants to indicate whether a colour-word was congruent or incongruent with its semantic meaning. The Depression, Anxiety and Stress Scale-21 (DASS-21) was completed to assess mood. Breathing frequency, Borg dyspnea rating, and breathing endurance time were ascertained.

RESULTS

Thirty young healthy adults (15F, 15M; median age = 24, IQR [23-26] years) completed the study. SCWT+ITL had lower SCWT accuracy compared to SCWT alone (98.6%, [97.1-100.0] vs 99.5%, [98.6-100.0]; p = 0.009). Endurance time was not different between ITL and SCWT+ITL (14.5 minutes, [6.9-15.0]) vs 13.7 minutes, [6.1-15.0]; p = 0.59). DASS-21 scores positively correlated with dyspnea scores during ITL (rho = 0.583, p<0.001) and SCWT+ITL (rho = 0.592, p<0.001).

CONCLUSIONS

ITL significantly reduced dual-task performance in healthy young adults. Lower mood was associated with greater perceived dyspnea during single and dual-task ITL. Considering the prevalence of dyspnea in respiratory disorders, the findings of this dual task paradigm warrant further exploration to inform dyspnea management during daily activities.

Breathlessness in older adults: What we know and what we still need to know

Breathlessness is common among older adults, but it is often hidden as "normal aging "or considered narrowly as a symptom of cardio-respiratory diseases. Studies on breathlessness in older adults are mostly focused on specific diseases, whereas older adults are characterized by multimorbidity and multi-system age-related impairments. This article aims to provide an overview of what is known so far on breathlessness in the general population of older adults and identify areas for further research. Research shows that breathlessness in older adults is a multifactorial geriatric condition, crossing the borders of system-based impairments and diseases, and a valuable independent prognostic indicator for adverse outcomes. Further research needs to investigate (1) the multi-factorial mechanisms of breathlessness in community-dwelling older adults including the role of respiratory sarcopenia; (2) the influence of affective and cognitive changes of older age on the perception and report of breathlessness; (3) the best way to assess and use breathlessness for risk prediction of adverse outcomes in general geriatric assessments; and (4) the most appropriate multi-modal rehabilitation interventions and their outcomes. Clinicians need to shift their approach to dyspnea from a disease symptom to a multifactorial geriatric condition that should be proactively searched for, as it identifies higher risk for adverse outcomes, and can be addressed with evidence-based interventions that can improve the quality of life and may reduce the risk of adverse outcomes in older adults.

Asthma's effect on brain connectivity and cognitive decline

Objective

To investigate the changes in dynamic voxel mirror homotopy connection (dVMHC) between cerebral hemispheres in patients with asthma.

Methods

Our study was designed using a case-control method. A total of 31 subjects with BA and 31 healthy subjects with matching basic information were examined using rsfMRI. We also calculated and obtained the dVMHC value between the cerebral cortexes.

Results

Compared with the normal control group, the dVMHC of the lingual gyrus (Ling) and the calcarine sulcus (CAL), which represented the visual network (VN), increased significantly in the asthma group, while the dVMHC of the medial superior frontal gyrus (MSFG), the anterior/middle/posterior cingulate gyrus (A/M/PCG), and the supplementary motor area (SMA) of the sensorimotor network decreased significantly in the asthma group.

Conclusion

This study showed that the ability of emotion regulation and the efficiency of visual and cognitive information processing in patients with BA was lower than in those in the HC group. The dVMHC analysis can be used to sensitively evaluate oxygen saturation, visual function changes, and attention bias caused by emotional disorders in patients with asthma, as well as to predict airway hyperresponsiveness, inflammatory progression, and dyspnea.

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.

The impact of emotional context on neural substrates of respiratory sensory gating

Psychological challenges have been found to impact respiratory symptom perception in healthy individuals as well as in patients with various neurological disorders. Human respiratory sensory gating is an objective measure to examine respiratory sensory information processing of repetitive respiratory mechanical stimuli in the central nervous system. With this electrophysiological method, patients with higher anxiety levels showed reduced respiratory sensory gating function in the cortex, and increased symptom perception. In addition, positive emotional contexts were found to increase the respiratory sensory gating function using RREPs. However, neural substrates related to emotional impacts on respiratory sensory gating remain still unclear. In the present study, we examined the emotion processing of respiratory sensory gating using functional magnetic resonance imaging. We hypothesized that positive compared with neutral stimuli would result in reduced brain activations in cortical areas with the paired occlusion paradigm. Thirty-five healthy adults participated in this event-designed fMRI experiment. Paired inspiratory occlusions (two transient occlusions with a 500 ms inter-stimulus-interval are delivered during one inspiration) were provided using an external trigger outside of the scanner. At least 40 paired inspiratory occlusions were collected for each trial. The experiment contained three runs during which participants underwent 12 min for the paired inspiratory occlusion paradigm while watching a fixation cross (the control condition), neutral and positive emotional picture series. The order of emotional picture series was randomized across the participants. Our results revealed an overall trend of reduction of brain activity from the neutral (minus fixation) condition, to the pleasant (minus fixation) condition. For bilateral thalamus and primary visual cortices, there was no significant difference in neural activation between the two contrasts of pleasant (Contrast_P–F) and neutral condition (Contrast_N–F). The activation of the mid-cingulate and the orbitofrontal cortex was lower in Contrast_P–F compared to Contrast_N–F. In conclusion, our results suggest that emotional context, especially positive valence, modulates neural correlates in middle cingulate cortex and orbitofrontal cortex in terms of respiratory sensory gating. Future studies are recommended to test emotional impacts on respiratory sensations in patients with neurological disorders.

The breathing brain: The potential of neural oscillations for the understanding of respiratory perception in health and disease

Dyspnea or breathlessness is a symptom occurring in multiple acute and chronic illnesses, however, the understanding of the neural mechanisms underlying its subjective experience is limited. In this topical review, we propose neural oscillatory dynamics and cross-frequency coupling as viable candidates for a neural mechanism underlying respiratory perception, and a technique warranting more attention in respiration research. With the evidence for the potential of neural oscillations in the study of normal and disordered breathing coming from disparate research fields with a limited history of interdisciplinary collaboration, the main objective of the review was to converge the existing research and suggest future directions. The existing findings show that distinct limbic and cortical activations, as measured by hemodynamic responses, underlie dyspnea, however, the time-scale of these activations is not well understood. The recent findings of oscillatory neural activity coupled with the respiratory rhythm could provide the solution to this problem, however, more research with a focus on dyspnea is needed. We also touch on the findings of distinct spectral patterns underlying the changes in breathing due to experimental manipulations, meditation and disease. Subsequently, we suggest general research directions and specific research designs to supplement the current knowledge using neural oscillation techniques. We argue for the benefits of interdisciplinary collaboration and the converging of neuroimaging and behavioral methods to best explain the emergence of the subjective and aversive individual experience of dyspnea.

The impact of unpredictability of dyspnea offset on dyspnea perception, fear, and respiratory neural gating

Dyspnea is a debilitating and threatening symptom in various diseases. Affected patients often report the unpredictability of dyspnea episodes being particularly anxiety-provoking and amplifying the perception of dyspnea. Experimental studies testing dyspnea unpredictability together with related neural processes, physiological fear responses, and dyspnea-related personality traits are sparse. Therefore, we investigated the impact of unpredictability of dyspnea offset on dyspnea perception and fear ratings, respiratory neural gating and physiological fear indices, as well as the influence of interindividual differences in fear of suffocation (FoS). Forty healthy participants underwent a task manipulating the offset predictability of resistive load-induced dyspnea including one unloaded safety condition. Respiratory variables, self-reports of dyspnea intensity, dyspnea unpleasantness, and fear were recorded. Moreover, respiratory neural gating was measured in a paired inspiratory occlusion paradigm using electroencephalography, while electrodermal activity, startle eyeblink, and startle probe N100 were assessed as physiological fear indices. Participants reported higher dyspnea unpleasantness and fear when dyspnea offset was unpredictable compared to being predictable. Individuals with high levels of FoS showed the greatest increase in fear and overall higher levels of fear and physiological arousal across all conditions. Respiratory neural gating, startle eyeblink, and startle probe N100 showed general reductions during dyspnea conditions but no difference between unpredictable and predictable dyspnea conditions. Together, the current results suggest that the unpredictable offset of dyspnea amplifies dyspnea perception and fear, especially in individuals with high levels of FoS. These effects were unrelated to respiratory neural gating or physiological fear responses, requiring future studies on underlying mechanisms.