The Social Regulation of Pain: Autonomic and Neurophysiological Changes Associated With Perceived Threat

Verbal support from a stranger reduces the development of mechanical hypersensitivity: behavioural and neurophysiological evidence

Handholding reduces experimentally induced acute pain, and buffers against the development of mechanical secondary hypersensitivity, an indirect proxy of central sensitization. Here, we tested if verbal support from a stranger, a common occurrence in clinical contexts, exerts the same effects. In this pre-registered study, forty-four healthy female participants were assigned to an alone or support group whereby a supportive female stranger encouraged them through the painful procedure leading to secondary mechanical hypersensitivity. Mechanical hypersensitivity was measured via self-reports and by the size of the anteroposterior and mediolateral spread of mechanical hypersensitivity. We investigated the moderating role of attachment style on self-reports, and the effects of support on skin conductance level, salivary cortisol, and pinprick evoked potentials. We also tested whether theta/beta ratio in the resting-state EEG predicted mechanical hypersensitivity. Self-reported ratings and the late part of the pinprick evoked potentials were reduced in the support group, but the spread of mechanical hypersensitivity was not. Attachment anxiety and avoidance moderated the self-reported intensity such that individuals with higher attachment anxiety and avoidance scores reported lower intensity ratings in the support group. No significant effect of the verbal support was observed on skin conductance level and salivary cortisol. The theta/beta ratio did not predict the extent of hypersensitivity. Our data indicate that in women, verbal support during intense pain leading to hypersensitivity is effective on some behavioural outcomes, but altogether the lack of group differences in cortisol, self-reported stress and skin conductance do not provide strong support for the stress-buffering hypothesis. PERSPECTIVE: Verbal support by a stranger during a painful procedure leading to secondary mechanical hypersensitivity attenuated the development of some measures of mechanical hypersensitivity and associated neural responses in healthy female participants. No evidence was found for a role of stress. DATA AVAILABILITY: The authors will make all data available upon request.

Social Buffering Effects during Craft Activities in Parallel Group Session Revealed by EEG Analysis and Parasympathetic Activity

INTRODUCTION

The therapeutic structure of occupational therapy (OT) includes groups. Although the presence of others is expected to be relaxing due to the social buffering effect and the tend and befriend theory, it has not been sufficiently validated in accordance with the therapeutic structure of OT. The aim of this study was to investigate the electrophysiological evidence for the effectiveness of parallel groups and states of concentration on craft activities used in OT.

METHODS

Thirty healthy young adults were used as controls to measure EEG and autonomic activity during craft activities in three conditions: alone, parallel, and nonparallel. EEG was analyzed using exact low-resolution electromagnetic tomography, and autonomic activity was analyzed using Lorenz plot analysis.

RESULTS

Parasympathetic activity was significantly higher in the parallel condition than in the alone condition. A significant negative correlation was found between current source density and parasympathetic activity in the region centered on the right insular cortex in the α1 band, and functional connectivity in regions including the anterior cingulate cortex and insular cortex was associated with autonomic activity.

CONCLUSION

Craft activities that occurred during frontal midline theta rhythm also increased parasympathetic activity. The results suggest that the parallel groups used in OT and the intensive state of craft activities induce a social buffering effect that increases parasympathetic activity despite the absence of physical contact or social support. This provides evidence for the effectiveness of the therapeutic structure of occupational activities and groups in OT.

Distinct Emotional and Cardiac Responses to Audio Erotica between Genders

Emotional and cardiac responses to audio erotica and their gender differences are relatively unclear in the study of the human sexual response. The current study was designed to investigate gender differences regarding positive and negative emotional responses to erotica, as well as its association with cardiac response. A total of 40 healthy participants (20 women) were exposed to erotic, neutral, and happy audio segments during which emotions and heart rate changes were evaluated. Our data showed distinct emotional responses to erotica between genders, in which women reported a higher level of shame than men and rated erotic audios as less pleasant than happy audios. Meanwhile, men reported erotic and happy audios as equally pleasant. These results were independent of cardiac changes, as both sexes demonstrated comparable heart rate deceleration when exposed to erotica relative to neutral and happy stimuli. Our results highlight the role of sociocultural modulation in the emotional response to erotica.

Analgesic efficacy of theta-burst stimulation for postoperative pain

OBJECTIVE

Repetitive transcranial magnetic stimulation (rTMS) may be a relevant method to assist postoperative pain. However, studies to date have only used conventional 10 Hz rTMS and targeted the DLPFC for postoperative pain. A more recent form of rTMS, termed intermittent Theta Burst Stimulation (iTBS), enables to increase cortical excitability in a short period of time. This preliminary double-blind, randomised, sham controlled study was designed to evaluate the efficacy of iTBS in postoperative care across two distinct stimulation targets.

METHODS

A group of 45 patients post laparoscopic surgery were randomised to receive a single session of iTBS over either the dorsolateral prefrontal cortex (DLPFC), primary motor cortex (M1), or Sham stimulation (1:1:1 ratio). Outcome measurements were number of pump attempts, total anaesthetic volume used, and self-rated pain experience, assessed at 1 hour, 6 hours, 24 hours, and 48 hours post stimulation. All randomised patients were analysed (n = 15 in each group).

RESULTS

Compared to Sham stimulation, DLPFC-iTBS reduced pump attempts at 6 (DLPFC = 0.73 ± 0.88, Sham = 2.36 ± 1.65, P = 0.031), 24 (DLPFC = 1.40 ± 1.24, Sham = 5.03 ± 3.87, P = 0.008), and 48 (DLPFC = 1.47 ± 1.41, Sham = 5.87 ± 4.34, P = 0.014) hours post-surgery, whereby M1 stimulation had no effect. No group effect was observed on total anaesthetics, which was mainly provided through the continuous administration of opioids at a set speed for each group. There was also no group or interaction effect on pain ratings. Pump attempts were positively associated with pain ratings in the DLPFC (r = 0.59, P = 0.02) and M1 (r = 0.56, P = 0.03) stimulation.

CONCLUSIONS

Our findings show that iTBS to the DLPFC reduces pump attempts for additional anaesthetics following a laparoscopic surgery. However, reduced pump attempts by DLPFC stimulation did not translate into a significantly smaller volume of total anaesthetic, due to the continuous administration of opioids at a set speed for each group.

SIGNIFICANCE

Our findings therefore provide preliminary evidence for iTBS targeting the DLPFC to be used to improve postoperative pain management.

Emotional dysregulation in women with endometriosis with cyclical and non-cyclical chronic pelvic pain

BACKGROUND

Endometriosis is a pathophysiological condition characterized by glands and stroma outside the uterus in regions such as the bladder, ureter, fallopian tubes, peritoneum, ovaries, and even in extra pelvic sites. One of the main clinical problems of endometriosis is chronic pelvic pain (CPP), which considerably affects the patients' quality of life. Patients with endometriosis may, cyclically or non-cyclically (80% of cases) experience CPP. High levels of anxiety and depression have been described in patients with endometriosis related to CPP; however, this has not been evaluated in endometriosis women with different types of CPP. Therefore, the research question of this study was whether there is a difference in the emotional dysregulation due to the type of pain experienced by women with endometriosis?

METHODS

This work was performed in the National Institute of Perinatology (INPer) in Mexico City from January 2019 to March 2020 and aimed to determine if there are differences in emotional dysregulation in patients with cyclical and non-cyclical CPP. 49 women from 18 to 52 years-old diagnosed with endometriosis presenting cyclical and non-cyclical CPP answered several batteries made up of Mini-Mental State Examination, Visual Analog Scale, Beck's Depression Inventory, State Trait-Anxiety Inventory, and Generalized Anxiety Inventory. Mann-Whitney U and Student's t-test for independent samples to compare the difference between groups was used. Relative risk estimation was performed to determine the association between non-cyclical and cyclical CPP with probability of presenting emotional dysregulation.

RESULTS

We observed that patients with non-cyclical CPP exhibited higher levels of depression and anxiety (trait-state and generalized anxiety) than patients with cyclical pain, p < 0.05 was considered significant. No differences were observed in pain intensity, but there was a higher probability of developing emotional dysregulation (anxiety or depression) in patients with non-cyclical CPP. No differences were observed in cognitive impairment.

CONCLUSIONS

Our data suggest that patients with non-cyclical (persistent) CPP present a higher emotional dysregulation than those with cyclical pain.

Security motives and negative affective experiences during the early months of the COVID-19 pandemic

OBJECTIVE

Self-regulation can help individuals cope during stressful events, but little is known about why and when this might occur. We examined if being more focused on prevention was linked to negative affective experiences during the COVID-19 pandemic. We also examined possible underlying mechanisms for this association, and whether social support buffered it.

DESIGN

Pre-registered longitudinal study, with surveys every 2 weeks over one month (N = 1269).

MAIN OUTCOME MEASURES

Regulatory focus and worry for health (T1), adherence to self-isolation and preventive health behaviours (T2), negative affective experiences, positive affect, frequency of online interactions, and perceived social support (T3).

RESULTS

Prevention focus was associated with health worries at baseline and linked to greater adherence to preventive health behaviours (T2). Only adherence to self-isolation was linked to more negative affective experiences (T3). Exploratory analyses showed that prevention focus was linked to more negative affective experiences (T3), but only for participants with fewer online interactions with their family and less perceived social support from family and friends.

CONCLUSIONS

Prevention motives in threatening times can be a double-edged sword, with benefits for health behaviours and consequences for negative affective experiences. Having a strong social network during these times can alleviate these consequences.

Concurrent TMS-EEG to Reveal the Neuroplastic Changes in the Prefrontal and Insular Cortices in the Analgesic Effects of DLPFC-rTMS

The dorsolateral prefrontal cortex (DLPFC) is an important target for repetitive transcranial magnetic stimulation (rTMS) to reduce pain. However, the analgesic efficacy of DLPFC-rTMS needs to be optimized, in which the mechanisms of action remain unclear. Concurrent TMS and electroencephalogram (TMS-EEG) is able to evaluate neuroplastic changes beyond the motor cortex. Using TMS-EEG, this study was designed to investigate the local and distributed neuroplastic changes associated with DLPFC analgesia. Thirty-four healthy adults received DLPFC or sham stimulation in a randomized, crossover design. In each session, participants underwent cold pain and TMS-EEG assessment both before and after 10-Hz rTMS. We provide novel findings that DLPFC analgesia is associated with a smaller N120 amplitude in the contralateral prefrontal cortex as well as with a larger N120 peak in the ipsilateral insular cortex. Furthermore, there was a strong negative correlation between N120 changes of these two regions whereby the amplitude changes of this dyad were associated with increased pain threshold. In addition, DLPFC stimulation enhanced coherence between the prefrontal and somatosensory cortices oscillating in the gamma frequency. Overall, our data present novel evidence on local and distributed neuroplastic changes associated with DLPFC analgesia.

Getting in touch: A neural model of comforting touch

Comforting touch involves contact distress-alleviating behaviors of an observer towards the suffering of a target. A growing number of studies have investigated the effects of touch on pain attenuation, focusing on the (toucher), the target (comforted) or both. Here we synthesize findings of brain mechanisms underlying comforting touch in the target and toucher to propose an integrative brain model for understanding how touch attenuates distress. Building on evidence from the pain and distress literatures, our model applies interchangeably to pain and distress regulation. We describe comforting touch as a feedback-loop that begins with distress experienced by the target, triggering an empathic response in the toucher which in turn reduces distress in the target. This cycle is mediated by interactions between the neural circuits associated with touch perception, shared distress, emotion regulation and reward as well as brain-to-brain coupling in the observation-execution system. We conclude that formulating a model of comforting touch offers a mechanistic framework for understanding the effects of touch as well as other social interactions involving social support.

Effects of Hand Holding on Anxiety and Pain During Prostate Biopsies: A Pilot Randomized Controlled Trial

BACKGROUND

Effective pain management is limited for patients during prostate biopsy (PBx). Touch support, such as hand holding, has stress-buffering benefits and effective analgesic effects. We conducted a prospective, single-center randomized clinical trial to assess whether hand holding can reduce patient anxiety, pain, and dissatisfaction during PBx.

METHODS

Between April 2020 and October 2020, 120 male patients were randomized into three groups: a hand holding with relatives (HR) group, a hand holding with strangers (HS) group and a control group. A visual analog scale (VAS) was used for self-assessments of pain and satisfaction. Anxiety levels were quantified according to the State-Trait Anxiety Inventory (STAI). Hemodynamic changes were also measured.

RESULTS

The degree of pain and anxiety in the hand-holding groups was significantly better than that in the control group (P<0.001), and the patients were more willing to undergo repeat PBx (P=0.017). The anxiety levels in the HR group were significantly lower than those in the HS group (P=0.019). During PBx, the changes in systolic blood pressure and heart rate in the hand-holding groups were more stable than those in the control group (P<0.01), and the fluctuations in heart rate in the HR group were smaller than those in the HS group (P<0.01).

CONCLUSION

Hand holding, especially with relatives, can promote incremental reductions in anxiety, pain and dissatisfaction in patients during PBx. Hence, we recommend hand holding with relatives as an effective adjunct during PBx.

Relationships Between Psychological, Social, Physical Activity, and Sleep Measures and Somatosensory Function in Individuals With Spinal Pain: A Systematic Review and Meta-analysis

OBJECTIVE

Somatosensory abnormalities are linked to clinical pain outcomes in individuals with spinal pain. However, a range of factors might confound the relationship between altered somatosensory function and clinical pain outcomes. This systematic review aimed to evaluate the literature to assess the level of evidence of associations between psychological, social, physical activity, and sleep measures and somatosensory function (assessed via sensory psychophysical testing) among individuals with spinal pain.

METHODS

A comprehensive literature search was performed in 6 electronic databases from their inception to June 2018. Two reviewers independently assessed the methodological quality using a modified Quality in Prognostic Studies (QUIPS) tool and supplemented with recommendations from the Critical Appraisal and Data Extraction for the Systematic Review of Prediction Modelling Studies (CHARMS) checklist and the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. The level of evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) system. Data were pooled to evaluate the strength of the relationships of interest.

RESULTS

Among the 17 factors identified in the included studies, pain catastrophizing, depression, and pain-related fear have significant negative (small to fair) associations with pain thresholds. A "very low" to "moderate" quality of evidence was found for all the investigated factors. Subgroup analysis showed a smaller effect size for pain catastrophizing/fear of movement and pain thresholds in individuals with low back pain.

CONCLUSIONS

Psychological factors are associated negatively with pain thresholds and they need to be adjusted when establishing predictive relationships between somatosensory function and pain outcomes in individuals with spinal pain.

Investigating the Influence and a Potential Mechanism of Self-Compassion on Experimental Pain: Evidence From a Compassionate Self-Talk Protocol and Heart Rate Variability

Previous studies have indicated a positive relationship between self-compassion and psychological and emotional well-being in chronic pain populations. However, evidence on the role and mechanisms of self-compassion in pain perception is largely limited. The current study was designed to investigate the effects and a potential mechanism of self-compassion on experimental pain. Thirty healthy participants underwent a compassionate self-talk protocol, which was followed by cold pain exposure during which high-frequency heart rate variability (HF-HRV) was evaluated. The compassionate self-talk protocol successfully generated compassionate statements among the participants. Our behavioral data showed lower pain ratings in the self-compassion compared to the control condition. Moreover, self-compassion manipulation resulted in higher HF-HRV during pain, which was associated with lower pain ratings. We present interesting findings that a short period of compassionate self-talk may decrease experimental pain as well as mechanistic evidence surrounding bodily control over pain-related arousal indicated by HF-HRV. PERSPECTIVE: This study presents the first line of evidence that a short period of compassionate self-talk may be sufficient to reduce experimental pain. We also demonstrate increased bodily control as a potential mechanism underlying this effect.

Shared Sensitivity to Physical Pain and Social Evaluation

Many studies have demonstrated a link between experiences of physical pain and those of social rejection, both of which can trigger cognitive processes involved in detecting, orienting toward, or reacting to potentially threatening events. This study tested the hypothesis that healthy individuals who are more sensitive to physical pain are also more sensitive to social rejection. We recruited participants with high or low pain-sensitivity (HPS and LPS), as assessed by scores on a pain-sensitivity questionnaire and confirmed by experimental pain-sensitivity assessment. A modified social-judgment task was adopted in which participants first provided expectations about being liked/disliked by "peers", and then received "peers" feedback indicating acceptance or rejection. While both groups rated rejection as more unpleasant than acceptance, this difference was greater in the HPS group. Electroencephalographic results showed that only participants in the HPS group exhibited greater early delta/theta-oscillations (δ/θ-oscillations) in response to rejection than to acceptance, regardless of whether the feedback was expected or unexpected. However, both groups consistently exhibited greater late δ/θ-oscillations in response to rejection when the feedback was unexpected. These results suggest that participants in the HPS group were more sensitive to social cues signaling acceptance or rejection at early stages of information processing. Furthermore, neither early nor late δ/θ-oscillations following nonsocial feedback (correct or incorrect time-estimation) differed between groups. Altogether, these results supported the idea of shared sensitivity in detecting potentially physical and social threats in the environment. PERSPECTIVES: This study showed the greater emotional reactions and early-latency δ/θ-oscillations in response to social evaluation among healthy individuals with high pain sensitivity. It supports the idea of shared sensitivity to physical pain and social evaluation, which could be governed by a common system for detecting and monitoring potentially environmental threats.