Experiential, autonomic, and respiratory correlates of CO2 reactivity in individuals with high and low anxiety sensitivity

Dynamic mechanisms that couple the brain and breathing to the external environment

Brain and breathing activities are closely related. However, the exact neurophysiological mechanisms that couple the brain and breathing to stimuli in the external environment are not yet agreed upon. Our data support that synchronization and dynamic attunement are two key mechanisms that couple local brain activity and breathing to external periodic stimuli. First, we review the existing literature, which provides strong evidence for the synchronization of brain and breathing in terms of coherence, cross-frequency coupling and phase-based entrainment. Second, using EEG and breathing data, we show that both the lungs and localized brain activity at the Cz channel attune the temporal structure of their power spectra to the periodic structure of external auditory inputs. We highlight the role of dynamic attunement in playing a key role in coordinating the tripartite temporal alignment of localized brain activity, breathing and input dynamics across longer timescales like minutes. Overall, this perspective sheds light on potential mechanisms of brain-breathing coupling and its alignment to stimuli in the external environment.

Cyclic vomiting syndrome: From pathophysiology to treatment

Cyclic vomiting syndrome (CVS) is a disorder characterized by recurrent and unpredictable episodes of intense vomiting, interspersed with periods of apparent wellbeing. This disorder, which primarily affects children and adolescents but can persist into adulthood, has recently been the subject of extensive study and analysis in the medical literature. The aim of the present review is to examine the most important aspects of the epidemiology, pathophysiology, subtypes, diagnostic criteria, and current management of CVS. Even though the exact etiology remains unknown, genetic factors (polymorphisms), nervous system alterations and autonomic dysregulation, and environmental factors (use and abuse of cannabinoids) are postulated as possible triggers. CVS has significant diagnostic challenges, given that there is no specific test for confirming its presence. Thorough evaluation of symptoms and the ruling out of other possible causes of recurrent vomiting are required. Management of CVS typically involves a multidisciplinary approach. Pharmacologic options are explored, such as antiemetics and preventive medications, as well as behavioral and psychologic support therapies. Treatment personalization is essential, adapting it to the individual needs of each patient. Despite advances in the understanding of CVS, it remains a significant clinical challenge. This disorder impacts the quality of life of those affected and their families, underscoring the ongoing need for research and the development of more effective treatment strategies.

Sedentary behaviour, but not moderate-to-vigorous physical activity, is associated with respiratory responses to acute psychological stress

BACKGROUND

Acute psychological stress induces respiratory responses, and stress-induced respiratory changes can be used to non-invasively reflect metabolic regulation. Respiratory and cardiovascular responses to stress are both driven by sympathetic mechanisms. Higher volumes of sedentary behaviour and lower volumes of physical activity are associated with elevated sympathetic tone and larger cardiovascular responses to stress. The aim of this study was to test whether these associations translate to measures of respiratory stress reactivity.

METHODS

Daily hours of sedentary behaviour (thigh-mounted activPAL) and moderate-to-vigorous physical activity (MVPA; wrist-mounted ActiGraph) were assessed across seven days. Breath-by-breath respiratory (e.g., breathing frequency [BF], end-tidal carbon dioxide partial pressure [PetCO₂], carbon dioxide output [V̇CO₂] and respiratory exchange ratio [RER]) responses to an 8-min Paced Auditory Serial Addition Test were then measured using a Cortex MetaLyzer3B.

RESULTS

Healthy participants (N = 61, mean age ± SD = 25.7 ± 8.9 years) recorded high volumes of sedentary behaviour (9.96 ± 1.48 h/day) and MVPA (1.70 ± 0.71 h/day). In adjusted models (with the inclusion of sedentary behaviour, MVPA, and other a priori selected covariates) hours of daily sedentary behaviour were associated with baseline to stress changes in BF (Β = 0.695, 95% CI = 0.281 - 1.109, p = .014), V_T (Β = -0.042, 95% CI = -0.058 - -0.026, p = .014), PetCO₂ (Β = -0.537, 95% CI = -0.829 - -0.245, p = .014), V̇CO₂ (Β = -0.008, 95% CI = -0.014 - -0.003, p = .030), and RER (Β = -0.013, 95% CI = -0.021 - -0.005, p = .022). Daily hours of MVPA were not linked with respiratory responses to stress.

DISCUSSION

Sedentary behaviour, but not MVPA, is associated with respiratory stress reactivity. Future work should untangle the underlying mechanisms of these findings and explore the consequences for cardiometabolic disease.

Anxiety Sensitivity Social Concerns Predicts Electrodermal Activity during the Niacin Biological Challenge Paradigm

Anxiety sensitivity social concerns (ASSC), or the fear of observable anxiety symptoms, is a risk factor for social anxiety. ASSC predicts anxiety following the niacin biological challenge, a paradigm in which niacin is used to manipulate facial flushing during a speech task. However, it remains unclear if ASSC predicts physiological arousal during this task. The current study was designed to examine the effects of ASSC on self-reported distress and electrodermal activity (EDA) during the niacin biological challenge in a sample of undergraduates (N = 36; M age = 18.9, SD = 0.84; 69.4% female). Participants were randomly assigned to one of four conditions in a 2 (100 mg niacin vs. 100 mg sugar) × 2 (instructional set) design. Participants completed a speech task in a virtual reality environment. Participants rated their distress halfway through the speech and EDA was averaged over four intervals. There was a main effect for ASSC on subjective distress. There was a significant ASSC by condition interaction predicting EDA, in that ASSC was related to EDA only in the niacin condition. ASSC also was more strongly related to EDA anticipating the speech. These findings highlight the role of ASSC in predicting anxiety and physiological arousal.

The Role of Anxiety Sensitivity and Expectancy Manipulation on Panic-Like Response to the 35% CO2 Challenge in Healthy Subjects

BACKGROUND

The 35% CO2 challenge is a well-established method triggering panic attacks under laboratory-controlled conditions. There is an ongoing debate whether single or the joined effects of the instructional set and anxiety sensitivity (AS) can alter the outcome of the challenge.

OBJECTIVES

The present study investigated the effects of instruction manipulation and AS on panic-like response to the 35% CO2 challenge.

METHODS

Eighty healthy subjects, with high or low levels of AS, were randomized into 4 groups based on standard/manipulated instructional sets as well as 35% CO2 mixture/room air inhalation. Subjects filled in the Visual Analogue Scale of Anxiety (VAAS), the Visual Analogue Scale of Fear (VAS-F), the VAS of Discomfort (VAS-D), and the Panic Symptom List (PSL). Blood pressure and heart rate were measured at pre- and posttest.

RESULTS

Hierarchical multiple regression analyses showed greater psychological responses at VAAS, VAS-F, VAS-D, and PSL and higher systolic blood pressure under 35% CO2 challenge if compared to room air inhalation while instructional set and AS did not influence the response.

CONCLUSIONS

The present study confirms that neither instructional test nor AS alter the outcome of the 35% CO2 challenge.

Cognitive Vulnerability in the Context of Panic: Assessment of Panic-Related Associations and Interpretations in Individuals with Varying Levels of Anxiety Sensitivity

Background

Cognitive models of panic disorder (PD) highlight the role of panic-related associations and interpretations. However, results are mixed and rely on specific measures. This study examined panic-related associations and interpretations using established and new paradigms in individuals varying on anxiety sensitivity (AS).

Methods

Associations were measured using a priming task and a novel Single Target Implicit Association Test (STIAT); interpretations were assessed using the Interpretation Bias Questionnaire (IBQ) and a novel Scrambled Sentences Task (SST). Symptoms were assessed via a provocation task (Straw Breathing Task, SBT).

Results

Panic-related interpretations correlated with AS and other PD-related measures. Of the association tasks, only the priming task correlated with one of the other PD-related measures. Panic-related interpretations assessed via the SST, but not priming, STIAT, and IBQ, predicted SBT reactivity. The relationship between AS and SBT reactivity was mediated by panic-related interpretations.

Conclusions

Our data provide support for panic-related interpretations as an important cognitive mechanism.

Emotional responding: Integration of multiple constructs and association with psychological health

OBJECTIVE

Numerous psychological constructs exist to describe different facets of emotional responding, but they have rarely been examined together. We empirically modeled the associations between four psychological constructs (mindfulness, emotional nonacceptance, experiential avoidance, and anxiety sensitivity) of individuals' responses to their affective experience, hypothesizing that a bifactor model would fit the data best.

METHOD

We used exploratory structural equation modeling, a novel latent variable modeling framework, to compare five measurement models of emotional responding in an online community sample (N = 307).

RESULTS

A bifactor model including a general emotional responding factor had substantial factor loadings from nearly all items, with mixed results for specific factors. Exploratory analyses supported the significant association of avoidant emotional responding and psychopathology/well-being.

CONCLUSION

The general avoidant emotional responding factor appears to overlap most directly with experiential avoidance and may be a transtheoretical construct relevant to mental health.

Temporal stability of multiple response systems to 7.5% carbon dioxide challenge

Self-reported anxiety, and potentially physiological response, to maintained inhalation of carbon dioxide (CO₂) enriched air shows promise as a putative marker of panic reactivity and vulnerability. Temporal stability of response systems during low-dose, steady-state CO₂ breathing challenge is lacking. Outcomes on multiple levels were measured two times, one week apart, in 93 individuals. Stability was highest during the CO₂ breathing phase compared to pre-CO₂ and recovery phases, with anxiety ratings, respiratory rate, skin conductance level, and heart rate demonstrating good to excellent temporal stability (ICCs≥0.71). Cognitive symptoms tied to panic were somewhat less stable (ICC=0.58) than physical symptoms (ICC=0.74) during CO₂ breathing. Escape/avoidance behaviors and DSM-5 panic attacks were not stable. Large effect sizes between task phases also were observed. Overall, results suggest good-excellent levels of temporal stability for multiple outcomes during respiratory stimulation via 7.5% CO₂.

Anxiety sensitivity and the anticipation of predictable and unpredictable threat: Evidence from the startle response and event-related potentials

There is growing evidence that heightened sensitivity to unpredictable threat is a core mechanism of dysfunction in anxiety disorders. However, it is unclear whether anxiety sensitivity is also associated with sensitivity to unpredictable threat. In the present study, 131 participants completed the Anxiety Sensitivity Index-3, which includes physical concerns (PC), social concerns (SC), and cognitive concerns (CC) subscales, and a predictable vs. unpredictable threat-of-shock task. Startle eyeblink and ERP responses (N100, P300) to the acoustic startle probes were measured during the task. PC and CC were associated with heightened and attenuated, respectively, startle for the unpredictable (but not predictable) condition. CC were also associated with attenuated probe N100 for the unpredictable condition only, and PC were associated with increased P300 suppression across the predictable and unpredictable conditions. This study provides novel evidence that the different anxiety sensitivity dimensions demonstrate unique relationships with the RDoC domains "acute" and "potential" threat.

Psychiatric disorders and symptoms in children and adolescents with sleep bruxism

OBJECTIVE

This study examines state-trait anxiety, anxiety sensitivity (AS), depressive symptom levels, and psychiatric disorders in children and adolescents with sleep bruxism (SB).

SUBJECTS AND METHOD

Thirty-five patients (aged 8-17 years) with a diagnosis of SB and 35 healthy controls were included in the study. All participants were evaluated for psychiatric disorders using a structured clinical interview and completed self-report questionnaires.

RESULTS

At least one psychiatric disorder was present in 42.9% of the patient group and 17.1% of the control group (p < 0.05). Trait and state anxiety, anxiety sensitivity, and the severity of depression symptoms were also higher in the SB group (p < 0.05). After the multivariate analysis, the associations between state and trait anxiety, depression, and SB became statistically insignificant, while the association with anxiety sensitivity persisted.

CONCLUSION

This study suggests that SB is related to AS, regardless of the severity of anxiety or depressive symptoms.