Pain and emotion as predictive factors of interoception in fibromyalgia

The Relationship Between Pain and Interoception: A Systematic Review and Meta-Analysis

Interoception refers to the ability to sense internal bodily sensations. Research suggests that dysfunctions in interoception may be implicated in the transition to chronic pain, however, little work has examined interoceptive ability in pain states. Therefore, this systematic review aimed to assess whether interoception is altered in individuals experiencing pain. Following a systematic search of 4 electronic databases from inception to February 2023, 28 studies were included. Outcomes of interoceptive accuracy, interoceptive sensibility, and interoceptive awareness were meta-analysed. The risk of bias was assessed, and the certainty of the evidence was evaluated. Meta-analyses indicated that those with chronic pain display reduced interoceptive accuracy and increased interoceptive sensibility. Subgroup analyses indicated that the change in interoceptive sensibility is dependent on the measure used, with those with chronic pain scoring higher on measures focusing on attention to bodily sensations, while also scoring lower on emotional reactivity. No difference in interoceptive awareness was observed between individuals with chronic pain and pain-free controls. Only one study was found that measured interoception in those experiencing acute pain, while another study recruited those experiencing recurrent pain. These findings suggest that while those with chronic pain self-report as more interoceptively aware, they are less accurate at detecting internal bodily signals. Further research investigating domains of interoception in those experiencing acute and recurrent pain is needed. Data should be interpreted with caution as the certainty of evidence was very low for all completed analyses. This review was registered on the PROSPERO International Prospective Register of Systematic Reviews (Registration ID = CRD42022318843). PERSPECTIVE: This review considered the relationship between interoception and pain and found that an individual's ability to accurately sense internal signals is decreased in those with chronic pain, despite them reporting being more aware of internal sensations. However, there remains little research examining interoception in non-chronic pain states.

Heightened interoception in adults with fibromyalgia

Previous research suggests that the processing of internal body sensations (interoception) affects how we experience pain. Some evidence suggests that people with fibromyalgia syndrome (FMS) - a condition characterised by chronic pain and fatigue - may have altered interoceptive processing. However, extant findings are inconclusive, and some tasks previously used to measure interoception are of questionable validity. Here, we used an alternative measure - the Phase Adjustment Task (PAT) - to examine cardiac interoceptive accuracy in adults with FMS. We examined: (i) the tolerability of the PAT in an FMS sample (N = 154); (ii) if there are differences in facets of interoception (PAT performance, PAT-related confidence, and scores on the Private Body Consciousness Scale) between an FMS sample and an age- and gender-matched pain-free sample (N = 94); and (iii) if subgroups of participants with FMS are identifiable according to interoceptive accuracy levels. We found the PAT was tolerable in the FMS sample, with additional task breaks and a recommended hand posture. The FMS sample were more likely to be classified as 'interoceptive' on the PAT, and had significantly higher self-reported interoception compared to the pain-free sample. Within the FMS sample, we identified a subgroup who demonstrated very strong evidence of being interoceptive, and concurrently had lower fibromyalgia symptom impact (although the effect size was small). Conversely, self-reported interoception was positively correlated with FMS symptom severity and impact. Overall, interoception may be an important factor to consider in understanding and managing FMS symptoms. We recommend future longitudinal work to better understand associations between fluctuating FMS symptoms and interoception.

The Fibromyalgia Decomposition Phenomenon: A Reflexive Thematic Analysis

Research is needed that can provide an illustration of the different biopsychosocial and environmental experiences of people with fibromyalgia to consider how healthcare professionals can best engage with the challenges that are faced. Qualitative research is well-positioned to do this. The current study used interpretive hermeneutic phenomenology situated within a pragmatic worldview, the aim being to obtain a deeper exploration of the fibromyalgia experience prior to commencing a novel intervention. A purposive sample of individuals with fibromyalgia were selected to undertake a single interview. The interviews were analysed using a thematic analysis. The themes identified key processes of the experience. A total of 16 participants (mean age: 47.1 years) took part. Three themes and 15 sub-themes were identified, together with a process linking different experiences together. The research from this small cohort provides a clear identification of multiple components influencing the experience of fibromyalgia and the decisions around lifestyle and choices made. From this, a novel decomposition/recomposition spiral has been identified, which will benefit patients and healthcare professionals alike. An earlier diagnosis and, thus, earlier and broader treatment options can help to improve functional outcomes.

Mind your heart to bear the weight: Cardiac interoception predicts action-related visual perception when wearing a heavy backpack

Visual perception can be modulated by the physiological potential for action. For instance, it was famously shown that a geographical slant appears steeper when wearing a heavy backpack than not wearing any. However, those results are not always replicated. In the present exploratory study, we test the hypothesis that the backpack weight's effect on perception relies on the ability of the cognitive system to integrate the physiological constraint's change rather than the change itself. Young adults (n = 54) wore an electrocardiogram monitor and completed a computerised task in which photographs of real geographical slants were displayed on a screen while wearing a heavy versus light backpack. The activity of the vagus nerve, as an index of physiological adaptability, was recorded as a proxy of the physiological state during the task. The participants also completed an interoception task assessing one's ability to detect his or her own heartbeat as the index of integration ability of the cognitive system. While Bayesian analyses revealed no difference in angle estimation between carrying a heavy versus light backpack, the results indicated that interoception predicted less accurate angle estimation only when wearing a heavy backpack. In contrast, there was anecdotal evidence that vagal activity changes predicted visual perception. Interoception might thus play a crucial role in the interplay between the physiological potential for action and action-related visual perception.

Neurophysiological and Psychosocial Mechanisms of Fibromyalgia: A Comprehensive Review and Call for An Integrative Model

Research into the neurobiological and psychosocial mechanisms involved in fibromyalgia has progressed remarkably in recent years. Despite this, current accounts of fibromyalgia fail to capture the complex, dynamic, and mutual crosstalk between neurophysiological and psychosocial domains. We conducted a comprehensive review of the existing literature in order to: a) synthesize current knowledge on fibromyalgia; b) explore and highlight multi-level links and pathways between different systems; and c) build bridges connecting disparate perspectives. An extensive panel of international experts in neurophysiological and psychosocial aspects of fibromyalgia discussed the collected evidence and progressively refined and conceptualized its interpretation. This work constitutes an essential step towards the development of a model capable of integrating the main factors implicated in fibromyalgia into a single, unified construct which appears indispensable to foster the understanding, assessment, and intervention for fibromyalgia.

Interoception, Voice Symptom Reporting, and Voice Disorders

OBJECTIVES

Interoception may play a role in how individuals perceive their voice disorder. The first objective of this study was to investigate relationships between interoception and voice disorder class (functional, structural, neurological). The second objective was to determine relationships between interoception and voice-related outcome measures between patients with functional voice and upper airway disorders and typical voice users. The third objective was to determine whether patients with primary muscle tension dysphonia (a type of functional voice disorder) had different levels of interoceptive awareness than typical voice users.

STUDY DESIGN

Prospective cohort study.

METHODS

One hundred subjects with voice disorders completed the multidimensional assessment of interoceptive awareness-2 (MAIA-2). Voice diagnosis and singing experience were also acquired from each patient's medical chart. Voice handicap (VHI-10) and Part 1 of the vocal fatigue index (VFI-Part1) scores were obtained from patients diagnosed with functional voice and upper airway disorders. MAIA-2, VHI-10, VFI-Part1, and singing experience were also obtained from 25 typical voice users. Multivariable linear regression models were used to assess the association between response variables and voice disorder class, adjusting for singing experience, gender, and age.

RESULTS

There were no significant group differences between voice disorder class (functional, structural, neurological) after adjusting for multiple comparisons. Participants with functional voice and upper airway disorders who scored significantly higher on the VHI-10 and VFI-Part1 had lower Attention Regulation sub-scores on the MAIA-2 (P's<0.05). Patients with primary muscle tension dysphonia scored significantly lower on the Emotional Awareness MAIA-2 subscale than typical voice users (P=0.005).

CONCLUSION

Patients with functional voice disorders with lower capabilities to attend to body sensations may score higher on voice-related patient-reported outcome measures, like the VHI-10 and VFI-Part1. Patients with primary muscle tension dysphonia may also have lower capabilities in processing their body sensations than typical voice users.

The two-stage therapeutic effect of posture biofeedback training on back pain and the associated mechanism: A retrospective cohort study

Introduction: Back pain is an extremely common symptom experienced by people of all ages and the number one cause of disability worldwide.² Poor posture has been identified as one of the factors leading to back pain. Digital biofeedback technology demonstrates the promising therapeutic ability in pain management through posture training. One common goal of such an approach is to increase users' posture awareness with associated movement correction. However, we lack a deep understanding of the biofeedback therapeutic mechanisms and the temporal dynamics of efficacy. Objective: This study investigates the temporal dynamics of the biofeedback learning process and associated outcomes in daily life settings, testing the mechanism of the biofeedback-associated pain reduction. Methods: This retrospective real-world evidence study followed 981 users who used the UpRight posture biofeedback platform. Piecewise mixed models were used for modeling the two-stage trajectory of pain levels, perceived posture quality, and weekly training duration following an 8-week biofeedback training. Also, the mediation effect of perceived posture quality on the analgesic effect of training duration was tested using Monte Carlo simulations based on lagged effect mixed models. Results: The analysis revealed significant pain level reduction (p <.0001) and posture quality improvement (p <.0001) during the first 4 weeks of the training, maintaining similar pain levels and perceived posture quality during the next 4 weeks. In addition, weekly training duration demonstrated an increase during the first 3 weeks (p <.001) and decreased during the next 5 weeks (p <.001). Moreover, training duration predicted following-week perceived posture quality (p <.001) and in turn perceived posture quality predicted following-week pain (p <.001) (p = 0.30). Finally, perceived posture quality mediated the effect of weekly training duration on the pain levels in 2 weeks (p <.0001). Conclusion: Our findings provide a better understanding of the therapeutic dynamic during digital biofeedback intervention targeting pain, modeling the associated two-stage process. Moreover, the study sheds light on the biofeedback mechanism and may assist in developing a better therapeutic approach targeting perceived posture quality.

Can interoceptive sensitivity provide information on the difference in the perceptual mechanisms of recurrent and chronic pain? Part I. A retrospective clinical study related to multidimensional pain assessment

OBJECTIVES

Although neurobiological research has shown that interoception plays a role in the perception of pain and its chronification, the relationship between interoceptive sensitivity and pain has not been definitively confirmed by clinical studies. The aim of this study was therefore to better understand the relationship between interoceptive sensitivity, somatization, and clinical pain, and to identify any differences in the interoceptive sensitivity of patients with recurrent vs. chronic pain.

METHODS

Scores from 43 Chronic pain subjects, assessed using ICD-11 Criteria; 42 healthy subjects (without pain or psychiatric disorders); and 38 recurrent pain subjects on the Multidimensional Assessment of Interoceptive Awareness (MAIA), Body Perception Questionnaire (BPQ-SF), Somatosensory amplification scale (SSAS), Patient Health Questionnaire (PHQ-15), Symptom Checklist-Revised (SCL-90-R), and Italian Pain Questionnaire (IPQ) were compared.

RESULTS

Negative attention to the body was indicated by higher scores of psychosomatic dimensions as SSAS, SCL90R somatization, and PHQ-15 in recurrent, but especially chronic pain (p<0.000 for all). An increase in psychosomatic dimension scores (i.e., somatization, somatosensory amplification) was associated with an increase in both autonomic nervous system reactivity (ANSR) dimension scores and the negative influence of the Not-worrying, attention regulation and trusting of the MAIA. In contrast, the presence of pain and scores for its dimensions with associated with lower supra-diaphragmatic activity as per the BPQ.

CONCLUSIONS

Pain chronification might depend on both the impairment of interoceptive sensitivity and an increase on psychosomatic dimensions via modification of ANSR hyperactivity and a reduction of the MAIA Not-worrying dimension.

Interoceptive accuracy and bias in somatic symptom disorder, illness anxiety disorder, and functional syndromes: A systematic review and meta-analysis

Somatic symptom disorder, illness anxiety disorder, and functional syndromes are characterized by burdensome preoccupation with somatic symptoms. Etiological models propose either increased interoceptive accuracy through hypervigilance to the body, or decreased and biased interoception through top-down predictions about sensory events. This systematic review and meta-analysis summarizes findings of 68 studies examining interoceptive accuracy and 8 studies examining response biases in clinical or non-clinical groups. Analyses yielded a medium population effect size for decreased interoceptive accuracy in functional syndromes, but no observable effect in somatic symptom disorder and illness anxiety disorder. The overall effect size was highly heterogeneous. Regarding response bias, there was a small significant effect in somatic symptom disorder and illness anxiety disorder. Our findings strengthen the notion of top-down factors that result in biased rather than accurate perception of body signals in somatic symptom disorder and illness anxiety disorder.

What do measures of self-report interoception measure? Insights from a systematic review, latent factor analysis, and network approach

Recent conceptualizations of interoception suggest several facets to this construct, including "interoceptive sensibility" and "self-report interoceptive scales", both of which are assessed with questionnaires. Although these conceptual efforts have helped move the field forward, uncertainty remains regarding whether current measures converge on their measurement of a common construct. To address this question, we first identified -via a systematic review- the most cited questionnaires of interoceptive sensibility. Then, we examined their correlations, their overall factorial structure, and their network structure in a large community sample (n = 1003). The results indicate that these questionnaires tap onto distinct constructs, with low overall convergence and interrelationships between questionnaire items. This observation mitigates the interpretation and replicability of findings in self-report interoception research. We call for a better match between constructs and measures.

Bodily Illusions and Motor Imagery in Fibromyalgia

Fibromyalgia (FM) is characterised by chronic, continuous, widespread pain, often associated with a sense of fatigue, non-restorative sleep and physical exhaustion. Due to the nature of this condition and the absence of other neurological issues potentially able to induce disorders in body representations per se, it represents a perfect model since it provides an opportunity to study the relationship between pain and the bodily self. Corporeal illusions were investigated in 60 participants with or without a diagnosis of FM by means of an ad hoc devised interview. In addition, motor imagery was investigated and illusions relating to body part movements and changes in body size, feelings of alienness, and sensations of body parts not belonging to one’s own body (disownership and somatoparaphrenic-like sensations) were found. Crucially, these symptoms do not correlate with any of the clinical measures of pain or functional deficits. The results showed that motor imagery was also impaired, and the severity of the deficits found correlated with the functional impairment of the participant. This indicates that disorders in body representations and motor imagery are part of the clinical expression of FM. However, while motor imagery seems to be linked to reduced autonomy and functional deficits, bodily illusions are independent and potentially represent a concurrent symptom.

Notes for life: a Henrian research methodology in psychology

Abstract This study aims to consider a Henrian methodology in Psychology. It is a theoretical, cross-sectional study that, drawing on the phenomenological tradition in Psychology, seeks to structure a research itinerary in two dimensions or layers of appearance. 1st – the intentional classical phenomenology display, and 2nd – the essence of the Henrian phenomenology manifestation. This route follows phases ranging from the design of the research and the constitution of the phenomenological view, reaching the synthesis scenario in which researchers can draw their conclusions about the content of the experience investigated. The insertion of the essence dimension manifestation enriches the traditional phenomenological method, opening up to Psychology the possibility of exploring the pathos avec. It provides Psychology with a methodological route to understand the dynamics of human experience beyond the health-disease model. It is necessary to continue the research in view of the development of the measurement instruments.

Alcohol use and interoception - A narrative review

Interoception, defined as the ability to perceive and interpret body signals, may play an important role in alcohol use disorder (AUD). Earlier studies suggested an association between interoception impairment and known risk factors for AUD (e.g., alexithymia, emotion dysregulation, impulsivity, pain). Neurobiological studies show that the neurotoxicity of alcohol affects various elements of the interoceptive system (especially the insula) at structural and functional levels, with differential short/long term impacts. Conversely, primary interoceptive impairments may promote alcohol consumption and foster the evolution towards addiction. Despite convincing evidence demonstrating that interoception impairment may be an important contributor to the development and course of AUD, only a few studies directly evaluated interoceptive abilities in AUD. The research shows that interoceptive accuracy, the objective component of interoception, is lower in AUD individuals, and is correlated with craving and emotion dysregulation. Interoceptive sensibility is in turn higher in AUD individuals compared to healthy controls. Moreover, there is evidence that therapy focused on improving the ability to sense signals from the body in addiction treatment is effective. However, important methodological limitations in interoceptive measures persist, and it is therefore necessary to further investigate the associations between interoception and AUD.

Interoception and social cognition in chronic low back pain: a common inference disturbance? An exploratory study

Aim: Lower interoceptive abilities are a characteristic of chronic pain conditions. Social support plays an important role in chronic low back pain (cLBP) but social cognitive skills have rarely been investigated. This study aimed to characterize interoceptive and social cognitive abilities in cLBP and to study the relationship between both domains that have been brought closer together by brain predictive coding models. Materials & methods: Twenty-eight patients with cLBP and 74 matched controls were included. Interoceptive accuracy (Heart Beat Perception Task), sensibility/awareness (Multidimensional Assessment of Interoceptive Awareness) and mental-states inference abilities (Mini-Social Cognition and Emotional Assessment) were assessed. Results: cLBP Patients had lower interoceptive accuracy and mentalizing performance. Conclusion: Less efficient interoceptive accuracy and mentalizing abilities were found in cLBP patients without correlation between these performances.

The Impact of a Peer Social Support Network from the Perspective of Women with Fibromyalgia: A Qualitative Study

Background: Fibromyalgia is a chronic and complex disease whose management by patients requires a high level of commitment. Patient empowerment therefore represents an important milestone in chronic disease treatment and control. We explored the impact of a peer social support network from the perspective of women with fibromyalgia. Methods: A generic qualitative design was proposed for the study, for which women who had been diagnosed with fibromyalgia were purposefully selected. Six semi-structured interviews were conducted, and the collected data were thematically analysed. Results: Three key themes emerged regarding the peer social support network: (1) empowerment (facilitating acceptance of the diagnosis and acting as a source of information); (2) effects on well-being and quality of life (attenuated the stigma, improved physical well-being, provided emotional support and was a socialization medium); and (3), valuable aspects (transmitted feelings of being understood and listened to and increased personal feelings of satisfaction). Conclusions: A peer social support network for women with fibromyalgia exerts positive effects on their physical, mental, and social well-being and empowers them to better manage their disease. Healthcare for women with fibromyalgia should include strategies that connect them through peer social support networks.

Revisiting the bipolar disorder with migraine phenotype: Clinical features and comorbidity

INTRODUCTION

To evaluate the prevalence and clinical correlates of lifetime migraine among patients with bipolar disorder (BD).

METHODS

In a cross-sectional study, we evaluated 721 adults with BD from the Mayo Clinic Bipolar Disorder Biobank and compared clinical correlates of those with and without a lifetime history of migraine. A structured clinical interview (DSM-IV) and a clinician-assessed questionnaire were utilized to establish a BD diagnosis, lifetime history of migraine, and clinical correlates.

RESULTS

Two hundred and seven (29%) BD patients had a lifetime history of migraine. BD patients with migraine were younger and more likely to be female as compared to those without migraine (p values <0.01). In a multivariate logistic regression model, younger age (OR=0.98, p<0.01), female sex (OR=2.02, p<0.01), higher shape/weight concern (OR=1.04, p=0.02), greater anxiety disorder comorbidities (OR=1.24, p<0.01), and evening chronotype (OR=1.65, p=0.03) were associated with migraine. In separate regression models for each general medical comorbidity (controlled for age, sex, and site), migraines were significantly associated with fibromyalgia (OR=3.17, p<0.01), psoriasis (OR=2.65, p=0.03), and asthma (OR=2.0, p<0.01). Participants with migraine were receiving ADHD medication (OR=1.53, p=0.05) or compounds associated with weight loss (OR=1.53, p=0.02) at higher rates compared to those without migraine.

LIMITATIONS

Study design precludes determination of causality. Migraine subtypes and features were not assessed.

CONCLUSIONS

Migraine prevalence is high in BD and is associated with a more severe clinical burden that includes increased comorbidity with pain and inflammatory conditions. Further study of the BD-migraine phenotype may provide insight into common underlying neurobiological mechanisms.

Visuospatial working memory abilities and spontaneous sensations perception

Aim: Body awareness arises when attending to and maintaining awareness of visuospatial body representations. By the same token, focussing on representations transfers them to working memory. Body awareness and working memory seemingly rely on similar processes and recruit common parietal areas involved in perception. Therefore, we asked whether visuospatial working memory abilities would define individual differences in the perception of spontaneous sensations (SPS), i.e., bodily sensations perceived in the absence of triggers (e.g., tactile stimulation or movement), when attending to the body.Method: Participants completed two visuospatial working memory tasks to assess various mechanisms: (i) the decay of representations was assessed through a Brown-Peterson task in which the delay between the memorandum presentation and its recall was manipulated, and (ii) the impact of distractors' interference and cognitive load (i.e., complexity) on recall performances were assessed through a complex span task that required the processing of distractors while maintaining a memorandum. A standard SPS task involving localization and characterization of SPS perceived on the hands was completed afterwards.Results: Low performance due to decay, distractors' interference and cognitive load in visuospatial working memory was associated with a decrease in the frequency of SPS. Additionally, low performance due to distractors' cognitive load predicted a decrease in the perception of surface-type sensations, and high performance despite distractors' interference led to a better perception of SPS on less sensitive areas of the hand.Conclusion: We discuss how visuospatial working memory processes might contribute to body awareness and perceptual distortions of the body.

Feeling Oneself Requires Embodiment: Insights From the Relationship Between Own-Body Transformations, Schizotypal Personality Traits, and Spontaneous Bodily Sensations

Subtle bodily sensations such as itching or fluttering that occur in the absence of any external trigger (i.e., spontaneous sensations, or SPS) may serve to locate the spatial boundaries of the body. They may constitute the normal counterpart of extreme conditions in which body-related hallucinations and perceptual aberrations are experienced. Previous investigations have suggested that situations in which the body is spontaneously experienced as being deformed are related to the ability to perform own-body transformations, i.e., mental rotations of the body requiring disembodiment. We therefore decided to consider whether the perception of SPS might relate to embodiment as assessed through (i) the ability to perform own-body transformations (OBT task) and (ii) schizotypal traits (Schizotypal Personality Questionnaire, or SPQ), since high degrees of schizotypy in the general population have been associated with more vivid perceptions and aberrant perceptual experiences. Then participants completed a standard SPS task. Our analysis revealed that the slower the response time in the OBT task, the more frequent the perception of SPS. This suggests that difficulties in disembodying and mentally transforming one's own body facilitate feeling oneself. Furthermore, a greater number of correct responses in the OBT task was associated with less frequent perception of SPS. This suggests that finding it easier to disembody and perform mental own-body transformations interferes with the ability to sense oneself. The results also show that higher schizotypal traits, as assessed through the SPQ, are associated with more frequent perception of SPS. Taken together, these results provide a coherent picture and suggest that embodiment is required in order to correctly feel oneself, as expressed through the perception of SPS. The ability to easily experience disembodiment reduces the sense of feeling oneself, and proneness to schizotypal traits produces body misperceptions that enhance and amplify this feeling. The results are discussed in the light of current knowledge and theories about body representations, taking into account attention and interoception as factors that influence body awareness. We offer explanations for perceptual aberrations, body-related delusions, and hallucinations based on misperceived or misinterpreted SPS, and we discuss possible mechanisms that may contribute to feeling and misperceiving oneself.

Interoceptive Sensibility, Alexithymia, and Emotion Regulation in Individuals Suffering from Fibromyalgia

INTRODUCTION

People suffering from fibromyalgia syndrome report various difficulties in emotional processing, possibly resulting from changes in bodily perception (interoception). In our study, we investigated the relationships between interoceptive sensibility (IS) and two disease-relevant emotional components (alexithymia and emotion regulation) in fibromyalgia sufferers compared to healthy individuals.

METHODS

Fifty-five fibromyalgia sufferers and 55 healthy individuals, matched with regard to age and gender, participated in our cross-sectional study. All participants completed the following self-report measures: the Multidimensional Assessment of Interoceptive Awareness, the Toronto Alexithymia Scale, and the Emotion Regulation Skills Questionnaire. Depression and anxiety scores served as confounding variables.

RESULTS

Fibromyalgia sufferers reported a stronger tendency to note as well as to avoid (unpleasant) body sensations. IS and psychopathology each explained about thirty percent of the variance in emotion regulation in fibromyalgia sufferers. Alexithymia was related to IS and emotion regulation in controls but not in fibromyalgia sufferers.

CONCLUSION

Disturbances in interoception could be seen as the starting point of emotional difficulties in people with fibromyalgia. Following the fear-avoidance-model, experiential avoidance may restrict patients' ability to adaptively regulate emotional states, possibly initiating a vicious cycle of psychological distress and pain.

The challenges of chronic pain and fatigue

In this review, we explore the challenges of chronic pain and fatigue in clinical practice. Both pain and fatigue are common, troubling and frequently overlapping symptoms, and we describe both the clinical burden and the 'clinical problem'. We explore commonly associated symptoms and possible pathological associations, including variant connective tissue (joint hypermobility), small fibre neuropathy, mast cell activation, dysregulated inflammatory and interoceptive processes, which may inform treatment targets. We suggest a multidisciplinary management approach.

Multidimensional Assessment of Interoceptive Abilities, Emotion Processing and the Role of Early Life Stress in Inflammatory Bowel Diseases

Perception of internal bodily sensations includes three dissociable processes: interoceptive accuracy, interoceptive sensibility, and interoceptive awareness. Interoceptive abilities play a crucial role in emotion processing and impairments of these processes have been reported in several psychiatric disorders. Studies investigating interoceptive abilities and their role in emotional experience in individuals with somatic disorders such as inflammatory bowel diseases (IBD) are sparse. Recent findings suggested an association between adverse childhood experiences (ACE) and the development of gastrointestinal disorders. The aim of the current study was to investigate the associations between the different dimensions of interoception and emotional processing in IBD while taking ACE into account. We recruited IBD patients in clinical remission (n = 35) and 35 healthy control participants (HC) matched for age, education and IQ. Interoception was measured as a three-dimensional construct. Interoceptive accuracy was assessed with the heartbeat tracking task and interoceptive sensibility with a self-report measure (Multidimensional Assessment of Interoceptive Awareness questionnaire). Emotional processing was measured using an experimental task, where participants were asked to rate the subjectively perceived valence and arousal when presented with positive, neutral and negative visual stimuli. IBD patients significantly differed in two interoceptive sensibility domains, Emotional awareness and Not-distracting. Patients reported greater awareness of the connection between bodily sensations and emotional states, while showing a stronger tendency to use distraction from unpleasant sensations compared with HC. Higher emotional awareness was linked to higher perceived intensity and arousal of negative stimuli. The strength of this relation was dependent on the severity of ACE, with severer traumatization being associated with a stronger association between emotional awareness and perceived valence and arousal. Our findings suggest that it is the subjective component of interoception, especially the one assessing interoceptive abilities within the scope of emotional experience, which affects emotional processing in IBD. This is the first study providing evidence that IBD patients did not differ in their perception of visceral signals per se but only in the subjective ability to attribute certain physical sensations to physiological manifestations of emotions. Our findings support the hypothesis that ACE affect the association between interoception and emotional processing.

Pain and Interoceptive Awareness Outcomes of Chronic Pain Patients With Spinal Cord Stimulation

OBJECTIVES

Meditation has been shown to improve outcomes for chronic pain by increasing patients' awareness of their own bodies. Some patients have an innate ability to leverage their mind-body connection, and this interoceptive awareness may aid them in garnering pain relief. We explored whether spinal cord stimulation (SCS) patients with greater innate awareness had better outcomes.

MATERIALS AND METHODS

We contacted 30 thoracic SCS patients with baseline and postoperative pain, psychological, and disability outcomes to complete the Multidimensional Assessment of Interoceptive Awareness (MAIA) survey. MAIA distinguishes between beneficial and maladaptive aspects of the perception of body sensations via six positive subscales (noticing, attention regulation, emotional awareness, self-regulation, body listening, and trusting) and two negative subscales (not distracting, not worrying). MAIA subscales and positive/negative groups were correlated with percentage change in Numerical Rating Scale (NRS), Oswestry Disability Index (ODI), Beck's Depression Inventory (BDI), Pain Catastrophizing Scale (PCS), and McGill Pain Questionnaire (MPQ).

RESULTS

Patients included 14 males/16 females with a mean age of 58. At a mean follow-up of 14.13 months (range 6-26), NRS, ODI, BDI, PCS, and MPQ showed improvements. Positive traits correlated with improvements in pain (MAIA-self regulation with NRS-worst [p = 0.018], NRS-least [p = 0.042], NRS-average [p = 0.006], NRS-current [p = 0.001]; MAIA-body listening with MPQ-total [p = 0.016] and MPQ-sensory [p = 0.026]). Improvement in PCS-total was associated with higher scores in noticing (p = 0.002), attention regulation (p = 0.017), emotional awareness (p = 0.039), and trusting (p = 0.047). PCS-rumination correlated with MAIA-positive total (p = 0.012). In contrast, better attention regulation signified less improvement in ODI (p = 0.043) and MPQ affective (p = 0.026).

CONCLUSIONS

Higher interoceptive awareness in SCS patients correlated with greater improvement following the procedure, particularly with regards to pain relief and pain catastrophizing. These findings suggest that patients with better mind-body connections may achieve greater pain relief following SCS in this patient population, thereby aiding providers in determining who may benefit from this intervention.

Altered Interoceptive Perception and the Effects of Interoceptive Analgesia in Musculoskeletal, Primary, and Neuropathic Chronic Pain Conditions

Chronic pain (CP) severely disrupts the daily life of millions. Interoception (i.e., sensing the physiological condition of the body) plays a pivotal role in the aetiology and maintenance of CP. As pain is inherently an interoceptive signal, interoceptive frameworks provide important, but underutilized, approaches to this condition. Here we first investigated three facets of interoceptive perception in CP, compared with pain-free controls. We then introduce a novel interoceptive treatment and demonstrate its capacity to reduce pain severity in CP, potentially providing complementary analgesic treatments. Study 1 measured interoceptive accuracy, confidence and sensibility in patients (N = 60) with primary, secondary musculoskeletal, and neuropathic CP. Compared with matched controls, CP participants exhibited significantly lower interoceptive accuracy and interoceptive confidence. Pain severity was predicted positively by interoceptive accuracy, anxiety and depression, and negatively by interoceptive confidence. Study 2 tested a promising new interoceptive treatment for CP, in a single-blind between-subjects design (N = 51) with primary, secondary musculoskeletal, and neuropathic CP patients. The treatment specifically activates the C-Tactile system, by means of controlled stimulation of interoceptive unmyelinated afferents, at 3 cm/s with a force of 2.5 mN. This treatment led to significant pain reduction (mean 23%) in the CP treatment group after only 11 min, while CP controls who received comparable but non-interoceptive stimulation reported no change in pain intensity. These studies highlight the importance of interoceptive approaches to CP and demonstrate the potential of this novel method of C-Tactile stimulation to provide complementary analgesic treatments.

Patients with fibromyalgia show increased beta connectivity across distant networks and microstates alterations in resting-state electroencephalogram

Fibromyalgia (FM) is a chronic condition characterized by widespread pain of unknown etiology associated with alterations in the central nervous system. Although previous studies demonstrated altered patterns of brain activity during pain processing in patients with FM, alterations in spontaneous brain oscillations, in terms of functional connectivity or microstates, have been barely explored so far. Here we recorded the EEG from 43 patients with FM and 51 healthy controls during open-eyes resting-state. We analyzed the functional connectivity between different brain networks computing the phase lag index after group Independent Component Analysis, and also performed an EEG microstates analysis. Patients with FM showed increased beta band connectivity between different brain networks and alterations in some microstates parameters (specifically lower occurrence and coverage of microstate class C). We speculate that the observed alterations in spontaneous EEG may suggest the dominance of endogenous top-down influences; this could be related to limited processing of novel external events and the deterioration of flexible behavior and cognitive control frequently reported for FM. These findings provide the first evidence of alterations in long-distance phase connectivity and microstate indices at rest, and represent progress towards the understanding of the pathophysiology of fibromyalgia and the identification of novel biomarkers for its diagnosis.

Altered Interoceptive Awareness in High Habitual Symptom Reporters and Patients With Somatoform Disorders

Objective: Altered interoception may play a major role in the etiology of medically unexplained symptoms (MUS). It remains unclear, however, if these alterations concern noticing of signals or if they are limited to the interpretation of signals. We investigated whether individuals with MUS differ in interoceptive awareness as assessed with the Multidimensional Assessment of Interoceptive Awareness (MAIA) questionnaire.

Methods: Study 1: A total of 486 individuals completed the Screening for Somatoform Disorders (SOMS-2). Thirty-two individuals each of the upper and lower decile of the SOMS distribution (low symptom reporters/LSR, high symptom reporters/HSR) completed the MAIA. Study 2: MAIA scores of individuals diagnosed with somatoform disorder (SFD; n = 26) were compared to individuals with major depressive disorder (MDD; n = 25) and healthy controls (HC; n = 26).

Results: HSR had lower scores than LSR on the MAIA scales Not-Distracting and Not-Worrying. The SFD and MDD groups showed lower scores than HC on the MAIA scales Not-Distracting, Self-Regulation, and Trusting. The MDD group scored lower than the other two groups on the scales Body Listening and Attention Regulation. There were no group differences on the scale Noticing.

Conclusion: HSR, SFD, and MDD patients do not differ from HC in the awareness of noticing of interoceptive signal processing, whereas cognitive facets of interoception, such as distraction or self-regulation are differentially affected. This highlights the necessity of including specifically targeted interventions, which improve interoceptive awareness, in the prevention and treatment of SFDs.

The association of different interoceptive dimensions with functional gastrointestinal symptoms

The aim of the current cross-sectional studies was to investigate the association of interoceptive dimensions with irritable bowel syndrome-related functional gastrointestinal symptoms using a multimethod approach. Two studies were conducted in Hungarian volunteers. Study 1 involved questionnaires regarding interoceptive sensibility. In Study 2, an experimental task was additionally used for the measurement of interoceptive accuracy. Reporters of high functional gastrointestinal symptoms were characterised by an increased perception of different somatic sensations together with a reduced trust in bodily signals. Our results support the hypothesis that there are interactions between interoceptive dimensions in the production of functional somatic symptoms. A data accessibility statement is included.

An Active Inference Approach to Interoceptive Psychopathology

Interoception refers to the process by which the nervous system senses and integrates signals originating from within the body, providing a momentary mapping of the body's internal landscape and its relationship to the outside world. Active inference is based on the premise that afferent sensory input to the brain is constantly shaped and modified by prior expectations. In this review we propose that interoceptive psychopathology results from two primary interoceptive dysfunctions: First, individuals have abnormally strong expectations of the situations that elicit bodily change (i.e., hyperprecise priors), and second, they have great difficulty adjusting these expectations when the environment changes (i.e., context rigidity). Here we discuss how these dysfunctions potentially manifest in mental illness and how interventions aimed at altering interoceptive processing can help the brain create a more realistic model of its internal state.

Spontaneous sensations reveal distorted body perception in complex regional pain syndrome (CRPS)

Distortions of body representation have been reported in Complex Regional Pain Syndrome (CRPS). The perception of sensations arising without external triggers (spontaneous sensations or SPS) was assessed here as a means of investigating distortions of body representation and awareness in CRPS. To avoid confounds between CRPS symptoms and SPS, lower-limb CRPS patients were included, whereas SPS were tested on the hands. Patients and controls were required to focus on their hands and to report the spatial and qualitative characteristics of SPS arising there. We found an ipsilateral decrease in the perception of thermal, pain-related and surface/mechanical SPS, as well as in the number of SPS-sensitive areas. The latter finding was predicted by decreased body awareness as assessed through questionnaires. A bilateral decrease in the perception of paresis-like SPS was also observed. Finally, the ipsilateral spatial distribution of SPS frequency and intensity underwent a shift from the fingers towards the lower parts of the palm. CRPS is likely to distort patient's body perception and awareness of the entire half-body ipsilateral to the affected limb, and even of both sides. Such disturbances are not manifested solely as a decrease in sensitivity, but sometimes as shifts in the spatial distribution of sensitivity.

Atypical bodily self-awareness in vicarious pain responders

Vicarious perception refers to the ability to co-represent the experiences of others. Prior research has shown considerable inter-individual variability in vicarious perception of pain, with some experiencing conscious sensations of pain on their own body when viewing another person in pain (conscious vicarious perception/mirror-pain synaesthesia). Self-Other Theory proposes that this conscious vicarious perception may result from impairments in self-other distinction and maintaining a coherent sense of bodily self. In support of this, individuals who experience conscious vicarious perception are more susceptible to illusions of body ownership and agency. However, little work has assessed whether trait differences in bodily self-awareness are associated with conscious vicarious pain. Here we addressed this gap by examining individual difference factors related to awareness of the body, in conscious vicarious pain responders. Increased self-reported depersonalization and interoceptive sensibility was found for conscious vicarious pain responders compared with non-responders, in addition to more internally oriented thinking (associated with lower alexithymia). There were no significant differences in trait anxiety. Results indicate that maintaining a stable sense of the bodily self may be important for vicarious perception of pain, and that vicarious perception might also be enhanced by attention towards internal bodily states. This article is part of a discussion meeting issue 'Bridging senses: novel insights from synaesthesia'.