Cardiac vagal control as a marker of emotion regulation in healthy adults: A review

A unifying conceptual framework of factors associated to cardiac vagal control

Cardiac vagal control (CVC) reflects the activity of the vagus nerve regulating cardiac functioning. CVC can be inferred via heart rate variability measurement, and it has been positively associated to a broad range of cognitive, emotional, social, and health outcomes. It could then be considered as an indicator for effective self-regulation, and given this role, one should understand the factors increasing and decreasing CVC. The aim of this paper is to review the broad range of factors influencing CVC, and to provide a unifying conceptual framework to integrate comprehensively those factors. The structure of the unifying conceptual framework is based on the theory of ecological rationality, while its functional aspects are based on the neurovisceral integration model. The structure of this framework distinguishes two broad areas of associations: person and environment, as this reflects adequately the role played by CVC regarding adaptation. The added value of this framework lies at different levels: theoretically, it allows integrating findings from a variety of scientific disciplines and refining the predictions of the neurovisceral integration model; methodologically, it helps identifying factors that increase and decrease CVC; and lastly at the applied level, it can play an important role for society regarding health policies and for the individual to empower one's flourishing.

Heart rate variability and emotion regulation among individuals with obesity and loss of control eating

Autonomic nervous system functioning, measured with heart rate variability (HRV), is associated with emotion regulation and likely contributes to binge eating. This study examined the link between HRV and binge eating severity and analyzed changes in HRV as a marker of emotion regulation in individuals with binge eating. Participants (n = 28) with obesity and loss of control eating reported overeating and loss of control episodes and completed an HRV assessment at rest and during a mental stressor. At rest, lower time-domain HRV was linked to more severe loss of control (SDNN B = -0.18, p = 0.03). Frequency-domain HRV was associated with more severe overeating (LFn B = 14.92, p = 0.03; HFn B = -14.81, p = 0.04). Frequency-domain HRV differed between resting and stressed conditions (p's < 0.001). Findings contribute to understanding emotion regulation in binge eating and guide future research and novel intervention development.

Cardiac vagal dysfunction moderates patterns of craving across the day in moderate to heavy consumers of alcohol

Background

Alcohol craving, a known correlate of vulnerability to Alcohol Use Disorder (AUD), has been found to be inversely related to cardiac vagal tone (CVT). Here we examine how resting CVT, CVT reactivity to a postural challenge, and their interaction influence craving during imposed alcohol abstinence and their usual drinking among moderate to heavy drinkers.

Methods

Participants were recruited from the local community (final n = 29) and assessed for CVT functioning via respiratory sinus arrhythmia (RSA) at rest (RSA-rest) and during a postural challenge (RSA-react). Craving intensity was assessed throughout the day during 3-day periods of imposed alcohol abstinence (abstained days) and drinking as usual (normal days) via Ecological Momentary Assessment (EMA). Multilevel statistical modeling assessed relationships between patterns of CVT and diurnal craving. The primary hypothesis of interest was that the interaction of RSA-rest with RSA-react would be significantly associated with increased craving across the day.

Results

Overall, craving increased throughout the day and significantly decreased after drinking (p < 0.001). There was a significant interaction between RSA-rest and RSA-react with plots revealing that this effect was driven by an aberrant craving pattern among participants with higher RSA-rest and a sluggish vagal brake in response to a postural shift—atypical RSA-react.

Conclusion

Although additional research is needed to corroborate these findings, our results suggest that moderate-heavy drinkers characterized by higher RSA-rest and atypical RSA-react exhibit aberrant patterns of craving across the day that may represent a risk factor for AUD.

Effects of an acute bout of physical exercise on reward functioning in healthy adults

Exercise has been proposed as a treatment for several psychiatric disorders. Exercise may act in part through beneficial effects on reward functioning, as it alters neurotransmitter levels in reward-related circuits. However, there has been little investigation of the effect of exercise on reward functions in humans. We hypothesized an acute bout of exercise would increase motivation for and pleasurable responses to rewards in healthy humans. In addition, we examined possible moderators of exercise's effects, including demographics, fitness and previous exercise experience. Thirty-five participants completed exercise and sedentary control sessions in randomized, counterbalanced order on separate days. Immediately after each activity, participants completed measures of motivation for and pleasurable responses to rewards, consisting of willingness to exert effort for monetary rewards and subjective responses to emotional pictures. Exercise did not increase motivation or pleasurable responses on average. However, individuals who had been running for more years showed increases in motivation for rewards after exercise, while individuals with less years running showed decreases. Further, individuals with higher resting heart rate variability reported lower arousal in response to all emotional pictures after exercise, while individuals with low heart rate variability reported increased arousal in response to all emotional pictures after exercise. General fitness did not have similar moderating effects. In conclusion, acute exercise improved reward functioning only in individuals accustomed to that type of exercise. This suggests a possible conditioned effect of exercise on reward functioning. Previous experience with the exercise used should be examined as a possible moderator in exercise treatment trials.

Encoding of Self-Referential Pain Catastrophizing in the Posterior Cingulate Cortex in Fibromyalgia

OBJECTIVE

Pain catastrophizing is a common feature of chronic pain, including fibromyalgia (FM), and is strongly associated with amplified pain severity and disability. While previous neuroimaging studies have focused on evoked pain response modulation by catastrophizing, the brain mechanisms supporting pain catastrophizing itself are unknown. We designed a functional magnetic resonance imaging (fMRI)-based pain catastrophizing task whereby patients with chronic pain engaged in catastrophizing-related cognitions. We undertook this study to test our hypothesis that catastrophizing about clinical pain would be associated with amplified activation in nodes of the default mode network (DMN), which encode self-referential cognition and show altered functioning in chronic pain.

METHODS

During fMRI, 31 FM patients reflected on how catastrophizing (CAT) statements (drawn from the Pain Catastrophizing Scale) impact their typical FM pain experience. Response to CAT statements was compared to response to matched neutral (NEU) statements.

RESULTS

During statement reflection, higher fMRI signal during CAT statements than during NEU statements was found in several DMN brain areas, including the ventral (posterior) and dorsal (anterior) posterior cingulate cortex (vPCC and dPCC, respectively). Patients' ratings of CAT statement applicability were correlated solely with activity in the vPCC, a main DMN hub supporting self-referential cognition (r = 0.38, P < 0.05). Clinical pain severity was correlated solely with activity in the dPCC, a PCC subregion associated with cognitive control and sensorimotor processing (r = 0.38, P < 0.05).

CONCLUSION

These findings provide evidence that the PCC encodes pain catastrophizing in FM and suggest distinct roles for different PCC subregions. Understanding the brain circuitry encoding pain catastrophizing in FM will prove to be important in identifying and evaluating the success of interventions targeting negative affect in chronic pain management.

Prescription opioid misusing chronic pain patients exhibit dysregulated context-dependent associations: Investigating associative learning in addiction with the cue-primed reactivity task

BACKGROUND

Associative learning undergirds the development of addiction, such that drug-related cues serve as conditioned stimuli to elicit drug-seeking responses. Plausibly, among opioid misusing chronic pain patients, pain-related information may serve as a conditioned stimulus to magnify opioid cue-elicited autonomic and craving responses through a process of second-order conditioning.

METHODS

We utilized a novel psychophysiological probe of pain-opioid conditioned associations, the Cue-Primed Reactivity (CPR) task. In this task, participants were presented with images as primes (200 ms) and cues (6000 ms) in pairs organized in four task blocks: "control-opioid," "pain-opioid," "control-pain," and "opioid-pain." Opioid-treated chronic pain patients (N = 30) recruited from an Army base in the Western United States were classified as opioid misusers (n = 17) or non-misusers (n = 13) via a validated cutpoint on the Prescription Drug Use Questionnaire (PDUQ; Compton et al., 2008). Opioid misuse status was examined as a predictor of HRV, craving, and mood responses on the CPR task.

RESULTS

HRV increased to a greater extent during the pain-opioid block compared to the control-opioid block for non-misusers compared to misusers (p = .003, η²_partial = 0.27). In contrast, craving increased to a greater extent from baseline to the pain-opioid block for misusers than for non-misusers (p = .03, η²_partial = .16).

CONCLUSIONS

Findings suggest that opioid-treated chronic pain patients exhibit Pavlovian conditioned responses to opioid cues strengthened by an associative learning process of second-order conditioning when primed by pain-related images. This pain-opioid contingency appears to become disrupted among individuals who engage in opioid misuse, such that opioid-related stimuli elicit motivational responses irrespective of pain-related contextual stimuli.