Towards a comprehensive assessment of interoception in a multi-dimensional framework

Predicting fluctuations in cardiac interoceptive accuracy and sensibility through additional heart rate variability reductions in everyday life

Cardiac interoception, assessed in terms of accuracy (IAcc) and sensibility (IS; beside others), is important for health and wellbeing. Ecological momentary assessment studies exploring the dynamics of cardiac interoception showed substantial fluctuations of IAcc and IS in everyday life. States of increased (physiologically indicated) stress, such as decreased heart rate variability (HRV), may hamper interoceptive skills, while more relaxed states (higher HRV) seem to go along with increased IAcc. We built on this and investigated if higher (physiological) stress indicated via HRV reductions independent of metabolic needs (i.e., additional HRV reduction, AddHRVr) could (differentially) predict IAcc and IS, respectively. In an initial sample of 119 participants, with data of (up to) three consecutive days, we simulated the predictive value of AddHRVr. We found that AddHRVr before an ambulatory cardiac interoception task predicted poor IAcc and higher IS. We replicated this pattern of findings in an independent sample of 66 participants. Both studies provide first insights into the dynamics of IAcc and IS in daily life, which seems to differ when following AddHRVr. This lays the groundwork for just in time adaptive interventions (JITAIs) supporting individuals in states of high vulnerability and promoting cardiac interoceptive skills.

Measuring interoception from infancy to childhood: A scoping review

BACKGROUND

Interoception is the ability to perceive, understand, and respond to internal bodily signals. Despite its importance, our knowledge of interoceptive abilities in the early stages of development remains limited. Delays or atypical patterns in interoceptive development may serve as early indicators of potential developmental psychopathology. Thus, assessing interoception in infancy and early childhood is essential for advancing our understanding of both typical and atypical developmental pathways.

OBJECTIVE

This scoping review summarises existing evidence regarding interoception from infancy to childhood and identifies the most common methods for assessing interoception in neurotypical pediatric populations.

DESIGN

A literature review was performed through a robust search of three scientific databases.

RESULTS

Among 663 studies, 24 articles met the inclusion criteria. The most commonly used methods in infancy were looking-time paradigms and brain-based implicit measures, such as Heart-Evoked Potentials (HEP). Researchers predominantly used child-adapted versions of Heart Tracking Tasks (HTT) for preschool-aged children. The primary methods for investigating interoceptive abilities among school-aged children included HTTs and self-report measures. Only one study used fMRI to examine mind-body connections in childhood, while two relied on parent reports.

CONCLUSIONS

This review offers a comprehensive overview of past and current methods for measuring interoception in the literature. It highlights the strengths and limitations of existing methodologies and presents recommendations to enhance our understanding of interoception in early human development.

Interoception and aging

Interoception refers to the body's perception and regulation of internal physiological states and involves complex neural mechanisms and sensory systems. The current definition of interoception falls short of capturing the breadth of related research; here, we propose an updated definition. Homeostasis, a foundational principle of integrated physiology, is the process by which organisms dynamically maintain optimal balance across all conditions through neural, endocrine, and behavioral functions. This review examines the role of interoception in body homeostasis. Aging is a complex process influenced by multiple factors and involving multiple levels, including physical, psychological, and cognitive. However, interoceptive and aging interoceptive interactions are lacking. A new perspective on interoception and aging holds significant implications for understanding how aging regulates interoception and how interoception affects the aging process. Finally, we summarize that arachidonic acid metabolites show promise as biomarkers of interoception-aging. The aim of this study is to comprehensively analyze interoceptive-aging interactions, understand the aging mechanism from a novel perspective, and provide a theoretical basis for exploring anti-aging strategies.

Experiences of interoception and anxiety in autistic adolescents: A reflexive thematic analysis

Most autistic adolescents experience anxiety. Interoception, defined as one's ability to detect and interpret bodily signals, might contribute to this. The aim of this exploratory, qualitative study was to gain a better understanding of interoceptive experiences in autistic adolescents and how this relates to anxiety. Semi-structured 1:1 interviews were conducted with 13 UK-based, autistic adolescents, aged 14-17 years, who reported experiencing significant, day-to-day anxiety. Interviews were analysed using a reflexive thematic analysis approach. Interoception appeared relevant to experiences of anxiety in most participants, although this influence was exerted through various routes. While hypoawareness of interoceptive signals led to a reduced ability to detect and regulate anxiety, hyperawareness became overwhelming and anxiety-inducing. Overly negative evaluations of interoceptive signals, including catastrophising about the signals indicating danger, also triggered anxiety. Relationships between interoception and anxiety appeared bidirectional, with anxiety also affecting interoceptive awareness and evaluation. Interoceptive experiences were variable both across and within participants, with factors such as arousal and cognitive overload affecting experiences. Future research should focus on assessing the feasibility of interventions based on the mechanisms identified here.Lay abstractAnxiety is common in autistic adolescents. The detection and interpretation of signals coming from inside the body (e.g. heartbeat and hunger) is assumed to be related to both anxiety and autism. We interviewed 13 autistic 14- to 17-year-olds who reported experiencing significant anxiety, to explore the role that bodily signals played in their experiences of anxiety. Across most participants, there did appear to be a relationship, although the exact way it was related varied. When participants were very aware of bodily signals, they could become overwhelming, but if they were not aware at all, then it was difficult for them to notice themselves getting anxious until it was too late. If participants interpreted these signals negatively, for example, assuming the signals meant something was wrong with their body, they were also more likely to feel anxious. Whether participants were aware or negatively evaluated these signals was very variable and appeared to be context-dependent.

The Body Can Balance the Score: Using a Somatic Self-Care Intervention to Support Well-Being and Promote Healing

Natural and human-made disasters, community violence, climate change, and political instability engender mental health problems worldwide. Childhood traumas, now recognized as commonplace and global in nature, augment the urgent need for mental health interventions that are accessible and scalable. The World Health Organization has called for innovative strategies that extend beyond traditional cognitive approaches. Biologically based methods are gaining recognition for their significant role in affect regulation and wellness promotion. This paper explores the potential for interventions focusing on interoceptive awareness, or noticing sensations arising from the body, to address mental health challenges, especially relevant for populations affected by trauma. The Community Resiliency Model (CRM)®, a low-intensity, body-based intervention that cultivates interoceptive awareness, is described and compared to other well-being interventions. Available research studies, program evaluations and anecdotal reports are presented in addition to CRM's biological and theoretical underpinnings. The neurobiology of trauma, interoception research, and the concept of neural synchrony are briefly introduced, further explaining the likely mechanism of action and an underlying rationale for the reported improvements in well-being and resilience among individuals and communities who learn CRM body awareness techniques. Given increasing global demand and limited access to conventional mental health services, CRM and the six core skills that are taught in this model offer a promising, transferable, self-care strategy. Community dissemination has the potential to expand access in underserved populations. This review concludes by suggesting future research directions, such as the exploration of biophysical outcomes, intra- and interpersonal synchrony, and evaluation of interoceptive training for emotional regulation and populations affected by trauma or violence.

Mapping acute alcohol effects on bodily sensations: A cross-dimensional interoceptive approach

BACKGROUND

Interoceptive processes may underlie maladaptive patterns of alcohol use. Bodily sensations experienced during alcohol intoxication could therefore reveal distinct mechanistic components relevant for addiction theory and research. Here, we apply novel tools to examine how intoxication impacts somatic awareness using bodily maps and a cardiac interoception task.

METHODS

In a double-blind, within-subjects, placebo-controlled study, social drinkers (n = 37, 17 female) were administered 0.4 g/kg of alcohol. We measured changes in self-reported bodily sensations during the ascending and descending limbs of the blood-alcohol curves using the emBODY tool. Additionally, we recorded biphasic measures of subjective alcohol effects (sedation and stimulation), changes in heart rate, and assessed psychophysical measures of cardiac beliefs using the heart rate discrimination task.

RESULTS

Acute alcohol administration altered bodily sensations, reflected by strong sensations in the chest, limbs, and head, with lesser effects in the placebo condition. Linear-mixed models examined correlates of bodily sensations across conditions. Extent of bodily sensations correlated with heart rate changes and breath alcohol content. In the ascending limb, bodily sensations negatively correlated with subjective stimulation and positively with sedation. Finally, extent of bodily sensations correlated with the metacognitive sensitivity of cardiac beliefs, suggesting a cross-dimensional integration between sensations and interoceptive awareness.

DISCUSSION

These findings highlight the value of bodily mapping in psychopharmacology, as interoceptive components of alcohol intoxication may provide a somatic basis for addiction. We interpret our results through low-sensitivity models, suggesting individuals with reduced bodily sensations during intoxication may face elevated risk for alcohol use disorder, a hypothesis that will be examined in future research.

Analysing the factor structure of the MAIA scale for pregnant women: Development of the MAIA-Preg

During pregnancy many elements of the bodily experience change, suggesting that measuring these constructs may require different instruments to those validated in the general population. This study reports an exploratory and confirmatory factor analysis exploration of the Multidimensional Assessment of Interoceptive Awareness (MAIA) in 716 pregnant women (mean gestation 26.4 weeks), from six different datasets who completed the MAIA online. Exploratory factor analysis condensed the questionnaire from a 32- to a 19- item scale, with five factor structure, which best fitted the data. Key subscales of Trust, Attention Regulation, Self-Regulation and Not Distracting remained robust. The one remaining item from the Noticing subscale loaded heavily with the Emotional Awareness subscale. Subscales of Body Listening, Not Worrying and Noticing did not load and therefore were excluded as factors. This led to the development of the scale referred to as the MAIA-Preg, which demonstrated a good fit with a confirmatory factor analysis along with good subscale reliability (ω= 0.73 -0.92), and measurement invariance for second and third trimesters. The MAIA-Preg was also found to be a good fit for separate non-pregnant (N = 396) and postnatal (N = 174) samples and thus provides a reliable and valid measure, providing nuanced information about the bodily experience in perinatal populations, allowing comparisons of changes to interoceptive sensibility the perinatal period.

Impaired gastric and urinary but preserved cardiac interoception in women with endometriosis

Endometriosis is a chronic inflammatory gynaecological condition frequently associated with chronic pelvic pain. Visceral hypersensitivity could be present, like in other chronic pain conditions, causing altered levels of interoception. So far, studies have explored interoceptive deficits in chronic pain individuals mainly using questionnaires or cardiac interoceptive accuracy tasks. Here, we explore the cardiac, gastric, and urinary domains to probe interoceptive differences between patients with endometriosis and healthy women. 30 patients and 30 controls underwent three interoceptive tasks for assessing the cardiac domain (using the Heartbeat Counting Task, HCT), the gastric domain (using the Water Load Test-II, WLT-II) and the bladder domain (using a novel Urinary Interoceptive Task, UIT). Participants also completed bladder interoceptive beliefs measures and subjective pain ratings for each endometriosis symptom (dysmenorrhea, dyspareunia, dyschezia, chronic pain). A positive correlation between the WLT-II and the UIT emerged in all participants (R = 0.47, p < 0.001), indicating that the lower the gastric interoceptive abilities, the lower the urinary ones. Moreover, compared to healthy controls, women with endometriosis exhibited lower scores in the WLT-II (t(58) = 4.6814, p < 0.001) and the UIT (t(39.931)= 5.1462, p < 0.001), as well as higher scores in the subjective bladder beliefs questions (t(57.346)= -4.0304, p < 0.001). Results indicate a dissociation between patients' poor objective performance on interoceptive tasks and their high bladder interoceptive beliefs. UIT scores were associated with pain symptoms, suggesting that patients, probably due to sensitisation, struggle to ignore discomfort sensations, resulting in reduced accuracy in detecting physiological signals coming from the pelvic area.

Validity Concerns About the Heartbeat Counting Task Extend to Alcohol Use disorder: Evidence From Subclinical and Clinical Samples

Theoretical models propose that interoception plays a role in addictive disorder. However, this assumption has been mostly tested using the heartbeat counting task (HCT), which is known to be contaminated by estimation strategies. An adapted version of the HCT (in which respondents report only felt heartbeats) has been developed to reduce estimation biases. Here, we examined the validity of the classical and adapted HCT versions in samples presenting alcohol use disorders. We recruited a clinical sample of 48 patients with severe alcohol use disorder (SAUD), matched with 41 healthy controls (HC), and a subclinical sample of 32 binge drinkers (BD), matched with 30 HC. Participants performed the classical HCT, adapted HCT, and a time estimation task. We additionally assessed mental health variables theoretically related to interoception (alexithymia, anxiety, childhood trauma, depression and emotion regulation). In all groups, HCT scores were smaller in adapted than classical HCT. Patients with SAUD, but not BD, showed lower HCT scores than matched controls, independently of the task. We found no correlation between HCT scores and psychological constructs. Heartbeats reported during classical HCT correlated with seconds reported during time estimation task for SAUD and matched HC, suggesting the use of time estimation strategies to perform the task. The largely reduced HCT performance in the adapted version, the association between HCT performance and time estimation performance and the lack of theoretically expected associations between HCT scores and psychological variables extend doubts on the validity of these tasks for measuring interoceptive accuracy in problematic alcohol consumption.

Neural Interoceptive Processing Is Modulated by Deep Brain Stimulation to Subcallosal Cingulate Cortex for Treatment-Resistant Depression

BACKGROUND

Symptoms of depression are associated with impaired interoceptive processing of bodily sensation. The antidepressant effects of subcallosal cingulate deep brain stimulation (SCC DBS) include acute change in bodily sensation, and the SCC target is connected to cortical regions critically involved in interoception. This study tested whether cortical interoceptive processing is modulated by SCC DBS for treatment-resistant depression.

METHODS

In 8 patients receiving SCC DBS for treatment-resistant depression, we used electroencephalography to measure the heartbeat-evoked potential (HEP), a putative readout of neural interoception, before surgery and over 6 months of treatment with DBS. We also examined the immediate effect of DBS on the HEP and correlated HEP change over time with outcomes of treatment for depression.

RESULTS

HEP amplitude increased from baseline to 6 months of DBS treatment, and this increase was associated with faster antidepressant response. Recording with stimulation on (vs. off) had an immediate effect on HEP in the laboratory. Overall, modulation of the HEP was most pronounced in sensors over the left parietal cortex.

CONCLUSIONS

Brain-based evidence implies an interoceptive element in the mechanism of treatment efficacy with DBS for treatment-resistant depression and substantiates a theorized connection between interoception and depression.

Comparisons of Body Awareness, Physical, and Cognitive Components and Relationships in Patients with Chronic Neck, Back, and Low Back Pain: A Cross-Sectional Study

PURPOSE

This study aimed to investigate the relationships between body awareness, body image, and physical and cognitive components in patients with neck, back, and low back pain. The secondary aim was to compare body awareness across these spine pain groups.

DESIGN

A cross-sectional study.

METHODS

Sixty-six patients with non-specific chronic spine pain were included, distributed among neck (n = 22, 28.18 ± 9.54 years), back (n = 21, 30.71 ± 12.26 years), and low back (n = 23, 38.43 ± 12.64 years) pain groups. Measurements included visual analogue scale for pain, Body Awareness Questionnaire, Stunkard Body Figure Scale, anthropometric measurements (weight, height, body mass index, waist-hip circumference, waist and hip ratio), one-leg stand test, Y balance test, New York Posture Analysis Scale, Melbourne Decision Making Scale, and Stress Coping Scale. Correlations were analyzed using Pearson/Spearman methods and compared with Kruskal Wallis/ANOVA tests according to their normal distribution.

RESULTS

Resting pain levels were 4.23 ± 2.66 cm (neck), 4.68 ± 2.62 cm (back) and, 4.32 ± 2.84 cm (low back). Body awareness was correlated with weight, body mass index, waist, and hip circumference in neck pain group (r = 0.610/p = .003; r = 0.569/p = .006, r = 0.498/p = .018; r = 0.445/p = .038). In the back pain group, as body awareness level increased, the level of coping with stress increased (r = 0.442/p = .045). No difference was found in intergroup comparisons (p > .05).

CONCLUSION

The study showed that body awareness and body image were associated with physical components (anthropometric measurements and balance) and cognitive components (stress coping skills). However, when comparing neck, back, and low back pain, no significant differences were found between any of the components.

CLINICAL IMPLICATIONS

A holistic approach addresses both physical and cognitive components for more balanced and effective care.

Impaired interoception in Colombian victims of armed conflict with PTSD: a preliminary HEP study

Individuals who have been exposed to violence are at high risk of developing mental health problems, particularly posttraumatic stress disorder (PTSD). A prominent example is the experience of Colombia, which has suffered systemic violence for more than half a century. Subjects with trauma-related disorders have problems regulating their emotions and facial emotion recognition (FER), a phenomenon that can be explained from a biological perspective by interoception. We conducted an experimental study using the heartbeat-evoked cortical potential amplitude (HEP) to determine the differences in FER and interoceptive priming in victims of armed conflict in Colombia with PTSD, complex posttraumatic stress disorder (CPTSD), and a control group. The results of behavioral studies indicate that individuals with PTSD and CPTSD exhibit impairments in interoceptive accuracy and deficits in the FER task. Compared with those in both the control and PTSD groups, the group of CPTSD victims demonstrated a decline in FER performance following interoceptive priming relative to exteroceptive priming. At the brain level, compared with controls, individuals with CPTSD presented a reduced amplitude of the HEP in the frontocentral regions during interoceptive processing. Significant differences were observed between the CPTSD and PTSD groups in the right frontal-lateral region during interoceptive priming. Our findings suggest alterations in FER interoception and HEP attenuation in armed conflict victims with PTSD and CPTSD. These results highlight the importance of interoception tasks in understanding the neurobiological mechanisms underlying emotional regulation and recognition in populations exposed to war trauma, and they may offer potential therapeutic strategies and targets for PTSD.

Trait dissociation is associated with dissociative experiences arising from disrupted multisensory integration

Dissociation is a transdiagnostic mental health symptom involving a sense of detachment from one's own body. A coherent percept of our body relies upon the smooth integration of different senses, such as vision and touch, which are processed by the brain at different speeds. We investigated the association between multi-sensory integration and dissociation in a N = 100 non-clinical sample. An immersive head-mounted display provided participants with a first-person view of their body while their arm was brushed by themselves or by the researcher. This mixed-reality setup allowed for the systematic variation of a delay to the visual feed, resulting in visual information being delayed relative to other senses (e.g. touch). Larger delays were associated with greater self-reported feelings of dis-ownership from the body. In addition, participants with high trait dissociation felt elevated sensations of dis-ownership from the body and were more sensitive to the multi-sensory delay, suggesting an increased tendency to 'fraction' senses in dissociation. Moreover, individuals with higher dissociation displayed similar cardiac reactivity to both self and other touch. These findings highlight two key mechanisms underlying dissociation; altered sensory-integration and increased awareness of self-action.

A cross-sectional study on the relationship between interoceptive sensitivity and somatic symptoms in young bipolar disorder patients

BACKGROUND

Bipolar disorder (BD) with somatic symptoms is a prevalent and refractory clinical syndrome in young patients. Interoception is an important mechanism for coordinating internal physiological and mood states to maintain individual homeostasis, and its mediating physiological systems and brain network dynamics undergo significant development from adolescence to young adulthood. It remains unclear whether interoception is altered and how it relates to somatic and mood symptoms in youths with BD.

METHODS

This study recruited 71 youths (aged 14-25) with BD during maintenance status and 111 age-matched controls. Demographic characteristics, interoceptive sensitivity, somatic symptoms, and symptoms of depression and anxiety were assessed. Mann-Whitney U tests, Kruskal-Wallis H test, partial correlation analysis, and multiple linear regression were used to explore the alteration of interoception in BD patients and its association with somatic and mood symptoms.

RESULTS

BD patients showed lower interoception sensitivity and higher somatic and mood symptoms than controls (p < 0.001). Those with somatic symptoms had the highest depression and anxiety (p < 0.001) but the lowest scores in not-distracting, not-worrying, self-regulation, and trust (p < 0.05). Interoceptive indicators correlated with mood and somatic symptoms (p < 0.05). Not-distracting was the sole predictor of somatic and mood issues, maintaining significance after controlling for mood symptoms (p < 0.05), highlighting attentional focus as a key factor in BD youths.

CONCLUSION

BD youths exhibit deficits in interoception sensitivity, somatic symptoms, and mood issues. The not-distracting aspect of interoception significantly correlates with mood and somatic symptoms in youths with BD, providing insights and targeted strategies for managing psychosomatic symptoms in this demographic.

LIMITATIONS

This study has several limitations. First, the control group's inclusion and exclusion criteria lacking clinical validation. Second, assessment for mood and somatic symptoms relied on screening tools rather than validated questionnaires, and structured clinical evaluations for BD were not conducted. Third, medication effects were not considered. Fourth, some psychiatric conditions (e.g., borderline personality disorder, obsessive-compulsive disorder, etc.) comorbid were not considered. Finally, causal relationships cannot be inferred, highlighting the need for longitudinal studies.

Breaking through the mind-body divide: patient priorities for interoception research

Background

Interoception-sensation, interpretation, and prediction of bodily signals-is reliably disrupted across a wide range of mental health conditions. A growing body of evidence suggests that interoception is a putative mechanism, or 'active ingredient', of effective psychological and pharmacological treatments. Anecdotally, patients with psychiatric disorders report differences in bodily experiences. However, formal priority setting by people with lived experience of mental health conditions has so far been overlooked in this rapidly expanding research area.

Methods

This article takes a mixed-methods approach to investigate experiences of bodily signals in individuals with mental health conditions and determine patients' research priorities. We recruited two UK samples in the context of an in-person workshop (N = 25) and online (N = 47), between April and July 2024. All contributors had a diagnosis of at least one mental health condition. Using a combination of written contributions and small group discussions, we explored the most relevant bodily sensations for patients' mental health, how bodily sensations were experienced by patients, and which research priorities were considered most important.

Findings

Patients' contributions emphasised the multimodal nature of interoception, in particular the importance of less frequently studied modalities such as the stomach and muscle tension, as well as the need to consider the causes and consequences of distressing bodily sensations. We summarise ten key research priorities for patients, spanning three themes: causes, management, and clinical/research approach to interoception in mental health. These priorities include investigating the impact of bodily signals on social contexts, techniques to manage distressing signals, and a shift of approach towards integrating mental and physical health in clinical/research settings.

Interpretation

Together, this broad scoping study establishes new, transdiagnostic, patient-led priorities for the developing field of interoception in psychiatry to ensure future research focusses on the areas of greatest impact for people with mental health conditions.

Funding

This work was supported by a Wellcome Mental Health award to C.L.N. and S.G. (226778/Z/22/Z), intramural funding from the UK Medical Research Council (MC/UU/00030/12), and a Wellcome Career Development Award to C.L.N. (226490/Z/22/Z). G.M. is funded by an ESRC DTP Studentship (RG84395). This research was also supported by the NIHR Cambridge Biomedical Research Centre (BRC-1215-20014).

Respiratory and cardiac interoceptive sensitivity in the first two years of life

Several recent theoretical accounts have posited that interoception, the perception of internal bodily signals, plays a vital role in early human development. Yet, empirical evidence of cardiac interoceptive sensitivity in infants to date has been mixed. Furthermore, existing evidence does not go beyond the perception of cardiac signals and focuses only on the age of 5-7 mo, limiting the generalizability of the results. Here, we used a modified version of the cardiac interoceptive sensitivity paradigm introduced by Maister et al., 2017 in 3-, 9-, and 18-mo-old infants using cross-sectional and longitudinal approaches. Going beyond, we introduce a novel experimental paradigm, namely the iBREATH, to investigate respiratory interoceptive sensitivity in infants. Overall, for cardiac interoceptive sensitivity (total n=135) we find rather stable evidence across ages with infants on average preferring stimuli presented synchronously to their heartbeat. For respiratory interoceptive sensitivity (total n=120) our results show a similar pattern in the first year of life, but not at 18 mo. We did not observe a strong relationship between cardiac and respiratory interoceptive sensitivity at 3 and 9 mo but found some evidence for a relationship at 18 mo. We validated our results using specification curve- and mega-analytic approaches. By examining early cardiac and respiratory interoceptive processing, we provide evidence that infants are sensitive to their interoceptive signals.

Psychometric network analysis of the Multidimensional Assessment of Interoceptive Awareness, version 2 (MAIA-2) in Peruvian adults

Interoception is a complex, multidimensional construct that refers to the nervous system's processing of internal bodily signals. Currently, there are no comprehensive measurement tools available to capture the full complexity of interoception. The Multidimensional Assessment of Interoceptive Awareness, Version 2 (MAIA-2), is a widely accepted and utilized interoceptive questionnaire that measures the multiple dimensions of conscious interoception through self-report. The aim of this study was to demonstrate the validity of a new Spanish translation of the MAIA-2 in Peruvian adults and to examine the dimensionality of the MAIA-2. A total of 414 Peruvian participants residing in Lima (Peru) were included; 85% were young adults between 18 and 27 years. The fit of the structural equation model (SEM) was assessed using confirmatory factor analysis (CFA). The dimensionality of the MAIA-2 was assessed using bootstrap exploratory bootstrap graph analysis (bootEGA). The results of the CFA suggest an oblique model (8 factors, 34 items) with modifications (items 11, 12, and 15 deleted). The bootEGA analyses indicate that a five-dimensional model is more parsimonious. These findings suggest that the MAIA-2 may have fewer dimensions than the original eight-dimensional theoretical model. The Peruvian Spanish version of the MAIA-2 proves to be a valid and reliable tool for assessing interoception in Peruvian adults, though slight variations in the dimensional structure were observed compared to the original model. This provides a solid basis for future research and clinical applications in Spanish-speaking contexts.

Exploring the impact of maternal early life adversity on interoceptive sensibility in pregnancy: implications for prenatal depression

PURPOSE

Pregnancy is a sensitive period of development in adult life characterized by massive changes in physical, emotional, and cognitive function. Such changes may be adaptive, e.g., facilitating adjustment to physical demands, but they may also reflect or contribute to risks inherent to this stage of life, e.g., prenatal depression. One cognitive ability that may undergo change during pregnancy and contribute to mental wellness is interoception - the ability to perceive, integrate, and model sensory information originating from the body. Strong interoceptive abilities are associated with lower rates of depression in non-pregnant adult populations, and interoception is generally weaker in individuals at higher risk for depression, for example, exposure to early life adversity (ELA). In the present online, cross-sectional study, we investigated whether interoception in pregnant women differed based on histories of ELA, in ways that increased their relative risk for prenatal depression symptoms.

METHODS

The pregnant individuals were in the second trimester of their first pregnancy and were compared to a group of nulliparous, non-parenting women.

RESULTS

Previous exposure to ELA significantly moderated pregnancy-related differences in self-reported interoception (interoceptive sensibility). A further moderated-mediation analysis revealed that the extent to which interoceptive sensibility buffered against depressive symptoms was conditional on ELA exposure, suggesting more ELA is associated with lower interoceptive sensibility during pregnancy, which increased prenatal depression risk.

CONCLUSIONS

Together this work suggests that levels of interoception during pregnancy are sensitive to previous adversity exposure. It also suggests that interoceptive-focused interventions for preventing/treating prenatal depressive symptoms in high-risk women may be worth exploring.

Pain in Tourette Syndrome: A Comprehensive Review

Objectives: Recent survey data suggest that a high proportion of patients with Tourette syndrome (TS) experience pain, yet pain features in TS have not been previously investigated in a systematic manner. This article reviews the current understanding and impact of pain in TS as well as identifies possible areas for emphasis for future research on pain in TS. Methods: Using a comprehensive search strategy in two relevant research databases (PubMed and Scopus), we searched for relevant peer-reviewed, primary research articles, and review articles. Search terms used were Tourette syndrome, tic disorder, pain, pain management, sensory, and sensory gating. Results: A total of 116 pertinent articles were identified. Pain is reported by 47%-60% of individuals with TS and may relate to different aspects of tic phenomenology or other causes. Pain is more prevalent among TS patients than in the general population and negatively impacts quality of life. To standardize future research efforts, we propose the following classification: tic-related immediate pain, tic-related delayed injury/pain, suppression-related pain, premonitory urge-related pain, and associated primary pain syndromes. Altered sensory gating and interoceptive processing abnormalities are possible mechanisms contributing to pain in TS but warrant further study. Despite pain prevalence, most TS clinical rating scales and outcome measures used in therapeutic studies do not incorporate sufficient information regarding pain. Therapies known to improve pain in non-TS conditions that are also reported to improve tics have not been investigated for their effects on pain among TS patients. Conclusion: TS can be associated with a chronic pain syndrome that negatively affects quality of life. Future research using a systematic framework is needed to better understand pain cause(s) and prevalence, develop appropriate assessment methods, establish outcome measures, and understand mechanisms of pain in TS. Such investigations are likely to lead to therapeutic options for this troublesome symptom.

The role of interoception in lifestyle factors: A systematic review

BACKGROUND

Interoception, the perception of the internal state of the body, offers an underrepresented and intriguing potential avenue for altering lifestyle-related behaviors. Interoception is intrinsically related to maintaining homeostasis and the flexible allostatic regulation of complex demands. Internal bodily states may also be influenced by lifestyle factors and related problems. This systematic review aimed to provide insight into the current state of evidence about the role of interoception in lifestyle factors.

METHODS

Studies from three databases (PubMed, Embase, and Web of Science) were screened for eligibility based on two inclusion criteria: 1) at least one measure of interoception (e.g., interoceptive accuracy, attention, or awareness), and 2) at least one measure of a lifestyle factor (i.e., alcohol consumption, cognitive leisure and relaxation activities, eating behavior, exercise, sleep, or smoking). Risk of bias was assessed using an adjusted quality score checklist, consisting of five items related to study design, population size, exposure measurement, outcome measurement, and adjustment for confounders.

RESULTS

The review included 73 studies. Out of the included studies, 51 measured interoceptive accuracy and 36 measured interoceptive attention. Six studies quantified interoceptive awareness. In terms of lifestyle factors, 26 studies on cognitive leisure and relaxation activities, 19 studies on eating behavior, 12 studies focused on alcohol consumption, 10 studies on exercise, five studies on smoking, and four studies on sleep were identified. Findings show positive relations between interoceptive domains and cognitive leisure and relaxation activities, eating behavior, and exercise. Conversely, the consumption of alcohol is negatively related to interoceptive domains. Studies in the smoking and sleep lifestyle factors were sparse and of varying methodological quality.

DISCUSSION

The findings of this review show that interoceptive domains are associated with various lifestyle factors, but the quality of the evidence is limited. Future longitudinal studies with more objective measures of interoception are needed in order to better understand the interrelations between interoception and lifestyle factors.

From feeling chilly to burning up: How thermal signals shape the physiological state of the body and impact physical, emotional, and social well-being

This review examines the role of thermal interoception-awareness of body temperature-in shaping physiological states and its impact on physical, emotional, and social well-being. We describe the neural pathways and mechanisms involved in thermal processing and environmental heat exchange and how thermal interoception influences both autonomic and behavioral responses, contributing to survival and homeostasis. Additionally, the review highlights the significance of thermal signals and thermoregulation in determining higher-order cognitive and emotional functions, such as regulating sleep patterns and activity levels, monitoring physical well-being, regulating emotions, and even social interactions. We describe the existing instruments for assessing body temperature and thermal awareness and call for further research to investigate the role of thermal interoception in emotional and social domains. We also discuss potential therapeutic applications, particularly in the context of psychosomatic and neurological disorders characterized by emotional dysregulation, disrupted sleep and mood patterns, social difficulties, and alterations in self-consciousness.

Eating Pathology and Interoceptive Sensibility Using the Brief Multidimensional Assessment of Interoceptive Awareness-2: Can There be Too Much of a Good Thing?

This study evaluated the factorial structure and invariance of the Multidimensional Assessment of Interoceptive Awareness-v2 (MAIA-2). We also investigated incremental validity of the MAIA-2 factors for predicting eating pathology beyond appetite-based interoception. US-based online respondents (N = 1294; Mage=48.7 ± 18.4; 63% cis women; 78% White) were sampled. We conducted hierarchical stepwise regressions, dominance analysis, and multiple-group confirmatory factor analyses across age, gender, and eating disorder symptoms. An 8-factor, 24-item Brief MAIA-2 (BMAIA-2) model showed optimal fit. Using strict criteria (Δ CFI > 0.002), configural, metric, and scalar invariance were supported. After controlling for appetite-based interoception, higher scores on body listening, noticing, and emotional awareness unexpectedly predicted worse eating pathology, while higher scores on not worrying, not distracting, and trusting predicted less eating pathology, as hypothesized. Dominance analysis showed no subscales contributed >2% unique variance to global disordered eating beyond appetite-based interoception. For loss of control eating, however, not worrying was the dominant BMAIA-2 predictor, explaining 5% unique variance beyond appetite-based interoception. Research supported the relevance of multiple interoceptive sensibility dimensions captured by the BMAIA-2 to understanding eating-based pathology. Future studies should consider assessing its incremental validity using behavioral tasks and autonomic biomarkers of interoception to better understand the complex interplay among interoceptive skills and eating behavior.

Discrepancies in the Definition and Measurement of Human Interoception: A Comprehensive Discussion and Suggested Ways Forward

Interoception has been the subject of renewed interest over the past 2 decades. The involvement of interoception in a variety of fundamental human abilities (e.g., decision-making and emotional regulation) has led to the hypothesis that interoception is a central transdiagnostic process that causes and maintains mental disorders and physical diseases. However, interoception has been inconsistently defined and conceptualized. In the first part of this article, we argue that the widespread practice of defining interoception as the processing of signals originating from within the body and limiting it to specific physiological pathways (lamina I spinothalamic afferents) is problematic. This is because, in humans, the processing of internal states is underpinned by other physiological pathways generally assigned to the somatosensory system. In the second part, we explain that the consensual dimensions of interoception are empirically detached from existing measures, the latter of which capture loosely related phenomena. This is detrimental to the replicability of findings across measures and the validity of interpretations. In the general discussion, we discuss the main insights of the current analysis and suggest a more refined way to define interoception in humans and conceptualize its underlying dimensions.

Exploring Individual Differences in Interoception Among Athletes Based on a Three-Dimensional Construct of Interoception

Previous studies demonstrated that sensorimotor training enhances interoceptive abilities. Athletes are highly engaged in performance-driven physical training and often incorporate-to varying degrees-sensorimotor training into their routines. In this study, we investigated the role of individual differences in interoception by comparing professional athletes of different performance levels and both sexes with recreational athletes and controls, applying a three-dimensional model of interoception. Twenty-six elite athletes, 52 recreational athletes, and 50 college students were recruited from national sports teams, local sports training centers, and local universities. We used the Multidimensional Assessment of Interoperative Awareness (MAIA), the Heartbeat Detecting Task (HDT), and a numeric rating scale based on HDT to measure interoceptive sensibility, accuracy, and awareness. At average, athletes showed significantly higher interoceptive sensibility, interoceptive accuracy, and interoceptive awareness than controls. Elite athletes reported significantly higher scores in all measures of interception compared to recreational athletes. Intriguingly, Non-Distracting for interoceptive sensibility was positively correlated with the level of experience in elite athletes. Male athletes had better interoceptive sensibility and interoceptive awareness compared to female athletes in the elite group, while no significant sex differences were detected in the other two groups. These results indicated that level of sport experience and sex are associated with differences in interoceptive accuracy, interoceptive sensibility, and interoceptive awareness. It also suggests that interoceptive ability is possibly an experience-dependent trait for athletic performance, which provides insight for improving sports performance through an approach of enhancing interoceptive ability.

Interoceptive ageing and the impact on psychophysiological processes: A systematic review

Interoception, the perception and response to internal bodily states, significantly influences physical and mental wellbeing. While ageing is associated with interoceptive decline, research has primarily examined selective dimensions of interoception. Understanding these changes is vital as the global population ages, addressing age-related health issues and sustaining psychological wellbeing. This systematic review synthesised findings from 22 studies on age-related interoceptive changes and their impact on psychophysiological processes. Results showed age-related declines (48.4 %), no age differences (32.3 %), an age-related increase (16.13 %), and an inverted U-shaped curvilinear relationship (3.23 %) in interoceptive sensitivity across age groups and interoceptive dimensions. Three patterns emerged regarding psychophysiological processes in older adults: altered mind-body connections with age were associated with reduced high-arousal and increased positive emotional experiences, cognitive protective effects, and improved body representation that correlated with better interoceptive sensitivity. These patterns indicate the complex relationships between interoceptive ageing and psychophysiological processes, showing both, aspects of decline and compensatory mechanisms. We propose future research avenues to elucidate the functional significance of different interoceptive dimensions across the lifespan for optimised psychological wellbeing and health behaviours in older adults.

Interoceptive Mechanisms and Emotional Processing

Interoception, the sensing of internal bodily signals, is intricately linked with the experience of emotions. Various theoretical models of emotion incorporate aspects of interoception as a fundamental component alongside higher-order processes such as the appraisal of internal signals guided by external context. Interoception can be delineated into different dimensions, which include the nature of afferent signals, the accuracy with which they can be sensed, their neural processing, and the higher-order interpretation of these signals. This review methodically evaluates these interoceptive dimensions through empirical research to illustrate their role in shaping emotions. Clinical and neurodevelopmental conditions characterized by altered emotional profiles, such as anxiety, depression, schizophrenia, posttraumatic stress disorder, emotionally unstable personality disorder, and autism, exhibit distinct changes in interoception. Various therapeutic approaches, including behavioral, pharmacological, and psychological strategies, may be efficacious for treating conditions associated with emotional alterations by targeting interoceptive mechanisms.

Allostatic Interoceptive Overload Across Psychiatric and Neurological Conditions

Emerging theories emphasize the crucial role of allostasis (anticipatory and adaptive regulation of the body's biological processes) and interoception (integration, anticipation, and regulation of internal bodily states) in adjusting physiological responses to environmental and bodily demands. In this review, we explore the disruptions in integrated allostatic interoceptive mechanisms in psychiatric and neurological disorders, including anxiety, depression, Alzheimer's disease, and frontotemporal dementia. We assess the biological mechanisms associated with allostatic interoception, including whole-body cascades, brain structure and function of the allostatic interoceptive network, heart-brain interactions, respiratory-brain interactions, the gut-brain-microbiota axis, peripheral biological processes (inflammatory, immune), and epigenetic pathways. These processes span psychiatric and neurological conditions and call for developing dimensional and transnosological frameworks. We synthesize new pathways to understand how allostatic interoceptive processes modulate interactions between environmental demands and biological functions in brain disorders. We discuss current limitations of the framework and future transdisciplinary developments. This review opens a new research agenda for understanding how allostatic interoception involves brain predictive coding in psychiatry and neurology, allowing for better clinical application and the development of new therapeutic interventions.

The relationship between self-reported interoception and anxiety: A systematic review and meta-analysis

Interoception, the processing of internal bodily sensations, is associated with various mental health conditions. In particular, anxiety is often considered to be the prototypical interoceptive disorder. However, empirical evidence is mixed, with meta-analytic work reporting no relationship between anxiety and cardiac interoceptive accuracy. Less explored, however, are the mixed results relating to anxiety and self-reported interoception. This meta-analysis of 71 studies explored the relationship between self-report measures of interoception and anxiety. Across 12 measures (20 subscales), anxiety was associated with increased negative evaluations of, frequency of, and sensitivity to, bodily signals. Anxiety was also associated with greater (negative) attention to bodily signals, and difficulties describing bodily signals and emotions. However, anxiety was not associated with the use of bodily signals to inform emotions (e.g., noticing emotionally induced bodily signals). Results are discussed considering the overlap between anxiety and interoception questionnaires, the lack of specificity of certain measures, and the potential confound of individual differences in questionnaire interpretation. We also discuss limitations of anxiety measures and the clinical relevance of findings.

Interoceptive Ability and Emotion Regulation in Mind-Body Interventions: An Integrative Review

It is increasingly recognized that interoceptive ability, the capacity to detect, interpret, and consciously integrate signals related to the physiological condition of the body, is central to emotion experience and regulation. Interoceptive ability can be trained and improved through mind-body interventions. This article attempts to provide an integrative review of the link between interoceptive ability and emotion regulation in mind-body interventions. To this aim, (1) we address the constructs of interoceptive ability and mind-body interventions in relation to the double pathway of emotion regulation, and (2) we include a review of selected empirical and qualitative studies. These show that mindfulness meditation affects the brain-body axis through top-down processing, improving both interoceptive ability and emotion regulation. Interventions based on bottom-up processing through body movement and emotional expression are illustrated, but it is argued that they are still under-investigated. In light of the literature reviewed, we contend that interoceptive ability is a crucial aspect associated with the effects of mind-body interventions on emotion regulation. Additionally, we suggest that if studied through both quantitative and qualitative methods, interoceptive ability may serve as a general construct that allows a more integrated view of the polarities related to the spectrum of embodied experience: top-down and bottom-up emotion processing, observational and non-observational body awareness, conscious and unconscious level of interoception.

A systematic review and meta-analysis of the relationship between subjective interoception and alexithymia: Implications for construct definitions and measurement

Although research indicates that self-reported interoception is associated with deficits in identifying and describing emotional experience, and externally oriented thinking styles (alexithymia), this relationship appears moderated by how interoception is measured. A systematic review and meta-analyses examined the association between self-reported interoception and alexithymia, investigating how different interoceptive questionnaires relate to alexithymia at global and facet levels. PsychINFO, PubMed, Scopus, and Web of Science databases were searched with predefined terms related to self-reported interoception and alexithymia. Three reviewers independently assessed articles, extracted data, and undertook risk of bias assessment. Thirty-two cross-sectional studies published between 1996 and 2023 were included. Random-effects meta-analyses and narrative synthesis indicated that global alexithymia was positively associated with measures of interoceptive confusion, autonomic nervous system reactivity, and heightened interoceptive attention, and inversely associated with interoceptive accuracy and adaptive interoception, indexed by composite Multidimensional Assessment of Interoceptive Awareness scores, but particularly interoceptive trusting, self-regulation, and attention regulation. These patterns were observed for alexithymic facets and stronger in magnitude for difficulty identifying feelings and difficulty describing feelings, relative to externally oriented thinking. Overall, results suggested that the association between self-reported interoception and alexithymia differs as a function of the interoceptive self-report. The review highlighted issues with construct definition and operationalisation and determined that existing interoceptive self-reports broadly capture maladaptive and adaptive sensing, attention, interpretation, and memory. The findings underscore the importance of specifying interoceptive constructs and using appropriate assessments to improve convergence between constructs and measurements, further suggesting potential clinical utility in using existing self-reports to measure interoception and alexithymia, facilitating interventions targeting mind-body connections.

WACARDIA: Graphical MATLAB software for Wireless Assessment of CARDiac Interoceptive Accuracy

Many theories of psychological function emphasize the importance of bodily sensations and the ability to accurately detect them, known as interoceptive accuracy. The most common measure of interoceptive accuracy uses heartbeat detection tasks such as the Whitehead Task, yet to our knowledge there are no freely accessible programs to conduct this task. In this paper, we present novel software called WACARDIA (Wireless Assessment of CARDiac Interoceptive Accuracy), which is free, open-source software that conducts the heartbeat detection task using Matlab and Psychtoolbox. WACARDIA contains several key features supporting participant engagement, operator convenience, and measurement accuracy. First, the program includes an optional practice trial of unlimited duration, a participant-facing graphical interface, and the ability to perform heartbeat detection training. Second, the operator is provided with a graphical user interface, live trial feedback, an accurate wireless electrocardiogram device, and a separate program to conduct the related Heartbeat Tracking task. Finally, the program ensures the accuracy of collected data by scheduling the delivery of tones with high precision and implementing fail-safes to automatically reset erroneous measurements. This paper includes flowcharts that help create transparency by describing our algorithm. We also outline customizable aspects of the program with the intent to have WACARDIA's algorithm expanded to accommodate more situations and applications. With this paper, we hope to encourage the practice of publicizing research software to contribute to the transparency, rigor, and reproducibility of scientific studies. WACARDIA and video tutorials are available at www.github.com/iankleckner/wacardia and http://wacardia.iankleckner.com.

He Who Seeks Finds (Bodily Signals): German Validation of the Interoceptive Attention Scale (IATS) and its Relationship with Subclinical Psychopathology

Alterations in interoception have been linked to psychopathology. Recent findings suggest that both the attention to and the accuracy of, interoceptive perceptions may be oppositely related to subclinical symptomatology. Thus, providing well-validated tools that tap into these interoceptive processes is crucial for understanding the relation between interoceptive processing and subclinical psychopathology. In the current study (N = 642), we aimed to (1) validate the German version of the Interoceptive Attention Scale (IATS; Gabriele et al., 2022), and (2) test the differential association of self-reported interoceptive attention and accuracy with subclinical symptomatology, including alexithymia, depressive, and anxious symptomatology. We observed that a one-factor solution is a well-fitting model for the IATS. Further, the IATS showed good internal consistency, convergent, and divergent validity, but poor test-retest reliability. Self-reported interoceptive attention and accuracy were unrelated to each other. However, IATS scores were positively related to all measures of psychopathology (except depressive symptomatology), whereas self-reported interoceptive accuracy scores showed negative or nonsignificant relations with these. Our data suggest that the IATS is a good instrument to measure self-report interoceptive attention in the German population. Further, we highlight the need to distinguish between constructs of interoception to better understand the relation between interoception and psychopathology.

First-person thought is associated with body awareness in daily life

Sensations from the body are thought to play a critical role in many aspects of conscious experience, including first-person thought. In the present set of studies, we examined within-person relationships between in-the-moment subjective awareness of sensations from the body and self-reported first-person thought in real-world settings using ecological momentary assessment (EMA) protocols. In Study 1, participants reported experiencing greater first-person thoughts in moments when they also reported heightened awareness of sensations from their body, and this relationship was stable over a 4-week period even with mean-level changes in body awareness and first-person thought. In Study 2, we replicated this association in a 1-week EMA protocol using both self-report measures and measures derived from participants' open-ended descriptions of their ongoing thoughts using a natural language processing approach. Taken together, findings shed light on the role of subjective body awareness in other facets of conscious experience.

How Bud Craig's Insights Reshape the Research on Pain and Mind-Body Therapies

With his elegant studies, Bud Craig determined the structural neural basis for interoception and critically expanded our conceptual understanding of it. Importantly, he placed pain in the framework of interoception and redefined pain as a homeostatic emotion. Craig understood emotions and pain as experiences based on inferential brain processes within the theoretical model of prediction processing. This chapter aims to give a brief overview of relevant research. Mind-body therapies, such as meditation, mindfulness, yoga, Tai Chi, and others, are included as first-line non-pharmacological approaches in clinical guidelines for the management of chronic pain. Craig's groundbreaking work provided the background for our contemporary understanding of mind-body therapies and for the key role that interoceptive processes play in these therapies as they apply to a wide range of clinical conditions, including pain. This chapter reviews the tremendous influence that Craig's work had on the current state of research on mind-body therapies for managing chronic pain and how it led to new directions for cutting-edge clinical and neuroscientific research.

Interoceptive sensibility and alcohol craving in Polish prisoners: the role of alexithymia and emotional dysregulation

Introduction

Alcohol craving, characterized by a strong desire or compulsion to consume alcohol, is a prominent symptom of substance dependence syndrome. Research indicates that alcohol craving is a significant factor leading to the termination of abstinence. The mechanisms underlying the activation of alcohol craving remain not fully understood. The urge to reach for alcohol may be stimulated by emotions, memories, thoughts, or bodily sensations, as well as external factors. It has been postulated that individuals with high levels of interoceptive sensibility tend to exhibit a high degree of alexithymia and emotion dysregulation in the context of alcohol craving. Deficits in identifying and verbalizing emotions, along with an operational thinking style, facilitate alcohol consumption by impeding accurate insight into one's mental state, thereby hindering the comprehension of bodily states, emotions, and the regulation of self.

Method

This study involved 160 inmates incarcerated in a prison in Poland, awaiting participation in therapy for individuals with substance dependence following psychiatric diagnosis. Four questionnaires were used in the study: multidimensional Assessment of Interoceptive Sensibility (MAIA) for interoceptive sensibility, Toronto Alexithymia Scale (TAS-20) for alexithymia, Difficulties in Emotion Regulation Scale (DERS) for emotional dysregulation, and the Penn Alcohol Craving Scale (PACS) for alcohol craving assessment.

Results

The results of the study are as follows: the study findings indicated that alexithymia and emotional dysregulation significantly mediates the relationship between interoceptive sensibility and alcohol craving. The indirect effect for both factors was found to be significant, similar to the indirect effect observed for alexithymia as an mediator. However, in the case of emotional dysregulation, no significant indirect effect was observed.

Conclusion

Our study provides insights into the potential contribution of interoceptive sensibility to the heightened risk of alcohol dependence. Specifically, impaired interoceptive sensibility may be associated with the development of alexithymia and emotional dysregulation, potentially rendering individuals more susceptible to alcohol craving. Interoceptive sensibility could serve as a prerequisite for the cultivation of positive emotional processing skills.

Insights into interoceptive and emotional processing: Lessons from studies on insular HD-tDCS

Interoception, the processing of internal bodily signals, is proposed as the fundamental mechanism underlying emotional experiences. Interoceptive and emotional processing appear distorted in psychiatric disorders. However, our understanding of the neural structures involved in both processes remains limited. To explore the feasibility of enhancing interoception and emotion, we conducted two studies using high-definition transcranial direct current stimulation (HD-tDCS) applied to the right anterior insula. In study one, we compared the effects of anodal HD-tDCS and sham tDCS on interoceptive abilities (sensibility, confidence, accuracy, emotional evaluation) in 52 healthy subjects. Study two additionally included physical activation through ergometer cycling at the beginning of HD-tDCS and examined changes in interoceptive and emotional processing in 39 healthy adults. In both studies, HD-tDCS was applied in a single-blind cross-over online design with two separate sessions. Study one yielded no significant effects of HD-tDCS on interoceptive dimensions. In study two, significant improvements in interoceptive sensibility and confidence were observed over time with physical preactivation, while no differential effects were found between sham and insula stimulation. The expected enhancement of interoceptive and emotional processing following insula stimulation was not observed. We conclude that HD-tDCS targeting the insula does not consistently increase interoceptive or emotional variables. The observed increase in interoceptive sensibility may be attributed to the activation of the interoceptive network through physical activity or training effects. Future research on HD-tDCS involving interoceptive network structures could benefit from protocols targeting larger regions within the network, rather than focusing solely on insula stimulation.

Interoception, network physiology and the emergence of bodily self-awareness

The interplay between the brain and interoceptive signals is key in maintaining internal balance and orchestrating neural dynamics, encompassing influences on perceptual and self-awareness. Central to this interplay is the differentiation between the external world, others and the self, a cornerstone in the construction of bodily self-awareness. This review synthesizes physiological and behavioral evidence illustrating how interoceptive signals can mediate or influence bodily self-awareness, by encompassing interactions with various sensory modalities. To deepen our understanding of the basis of bodily self-awareness, we propose a network physiology perspective. This approach explores complex neural computations across multiple nodes, shifting the focus from localized areas to large-scale neural networks. It examines how these networks operate in parallel with and adapt to changes in visceral activities. Within this framework, we propose to investigate physiological factors that disrupt bodily self-awareness, emphasizing the impact of interoceptive pathway disruptions, offering insights across several clinical contexts. This integrative perspective not only can enhance the accuracy of mental health assessments but also paves the way for targeted interventions.

Understanding the mechanisms of fatigue in multiple sclerosis: linking interoception, metacognition and white matter dysconnectivity

One of the most prominent symptoms in multiple sclerosis is pathological fatigue, often described by sufferers as one of the most debilitating symptoms, affecting quality of life and employment. However, the mechanisms of both, physical and cognitive fatigue in multiple sclerosis remain elusive. Here, we use behavioural tasks and quantitative MRI to investigate the neural correlates of interoception (the ability to sense internal bodily signals) and metacognition (the ability of the brain to assess its own performance), in modulating cognitive fatigue. Assuming that structural damage caused by multiple sclerosis pathology might impair the neural pathways subtending interoception and/or metacognition, we considered three alternative hypotheses to explain fatigue as a consequence of, respectively: (i) reduced interoceptive accuracy, (ii) reduced interoceptive insight or (iii) reduced global metacognition. We then explored associations between these behavioural measures and white matter microstructure, assessed by diffusion and magnetisation transfer MRI. Seventy-one relapsing-remitting multiple sclerosis patients participated in this cross-sectional study (mean age 43, 62% female). Patient outcomes relevant for fatigue were measured, including disability, disease duration, depression, anxiety, sleepiness, cognitive function, disease modifying treatment and quality of life. Interoceptive and metacognitive parameters were measured using heartbeat tracking and discrimination tasks, and metacognitive visual and memory tasks. MRI was performed in 69 participants, including diffusion tensor MRI, neurite orientation dispersion and density imaging and quantitative magnetisation transfer. Associations between interoception and metacognition and the odds of high cognitive fatigue were tested by unconditional binomial logistic regression. The odds of cognitive fatigue were higher in the people with low interoceptive insight (P = 0.03), while no significant relationships were found between fatigue and other interoceptive or metacognitive parameters, suggesting a specific impairment in interoceptive metacognition, rather than interoception generally, or metacognition generally. Diffusion MRI-derived fractional anisotropy and neurite density index showed significant (P < 0.05) negative associations with cognitive fatigue in a widespread bilateral white matter network. Moreover, there was a significant (P < 0.05) interaction between cognitive fatigue and interoceptive insight, suggesting that the poorer the white matter structure, the lower the interoceptive insight, and the worse the fatigue. The results point towards metacognitive impairment confined to the interoceptive domain, in relapsing-remitting patients with cognitive fatigue. The neural basis of this impairment is supported by a widespread white matter network in which loss of neurite density plays a role.

Eye tracking is more sensitive than skin conductance response in detecting mild environmental stimuli

The skin conductance (SC) and eye tracking data are two potential arousal-related psychophysiological signals that can serve as the interoceptive unconditioned response to aversive stimuli (e.g. electric shocks). The current research investigates the sensitivity of these signals in detecting mild electric shock by decoding the hidden arousal and interoceptive awareness (IA) states. While well-established frameworks exist to decode the arousal state from the SC signal, there is a lack of a systematic approach that decodes the IA state from pupillometry and eye gaze measurements. We extract the physiological-based features from eye tracking data to recover the IA-related neural activity. Employing a Bayesian filtering framework, we decode the IA state in fear conditioning and extinction experiments where mild electric shock is used. We independently decode the underlying arousal state using binary and marked point process (MPP) observations derived from concurrently collected SC data. Eight of 11 subjects present a significantly (P-value < 0.001 ) higher IA state in trials that were always accompanied by electric shock ( CS + US + ) compared to trials that were never accompanied by electric shock ( CS - ). According to the decoded SC-based arousal state, only five (binary observation) and four (MPP observation) subjects present a significantly higher arousal state in CS + US + trials than CS - trials. In conclusion, the decoded hidden brain state from eye tracking data better agrees with the presented mild stimuli. Tracking IA state from eye tracking data can lead to the development of contactless monitors for neuropsychiatric and neurodegenerative disorders.

Interoceptive attention and mood in daily life: an experience-sampling study

Theories of emotion ascribe a fundamental role to the processing of bodily signals (interoception) in emotional experience. Despite evidence consistent with this, current knowledge is limited by a focus on interoceptive accuracy and laboratory-based interoception measures. This experience-sampling study examines how state interoceptive attention and state emotional experience are related in everyday life, providing the first data to our knowledge examining: (1) within-subject fluctuations in interoceptive attention across domains, and (2) the relationship between trait and state interoception. Compared with rates of exteroceptive attention (auditory attention: engaged 83% of the time), interoceptive signals captured attention approximately 20% of the time, with substantial within- and between-person variability across domains. There were relationships between interoceptive attention and emotion in daily life (greater attention being associated with more negative valence and fatigue) that were specific to interoceptive attention (different patterns were observed with exteroceptive attention). State measures of interoceptive (but not exteroceptive) attention were correlated with the trait interoceptive attention, but not accuracy. Results underscore the relationship between interoceptive attention and emotion, providing new insights into interoceptive attention and the structure of interoceptive ability. Future research should examine the source(s) of within- and between-person variability in interoceptive and exteroceptive attention and its relationship with emotional experience. This article is part of the theme issue 'Sensing and feeling: an integrative approach to sensory processing and emotional experience'.

Interoceptive Processing in Functional Gastrointestinal Disorders

Functional gastrointestinal disorders (FGIDs) are characterized by chronic gastrointestinal symptoms in the absence of overt pathology and affect a significant percentage of the worldwide population. They are commonly accompanied by co-morbid psychiatric symptomatology and are associated with significant suffering and great healthcare services utilization. There is growing evidence that dysregulation of the gut-brain axis and disturbances in the processing of afferent interoceptive signals lie at the heart of these disorders. In this context, the aim of the current review was to detect and critically review original articles focusing on the role of interoception in the pathophysiology of FGIDs. Our search yielded 38 relevant studies. FGID patients displayed increased visceral sensitivity, enhanced attention to gastrointestinal interoceptive cues, and greater emotional arousal when coping with gut-derived sensations. Neuroimaging studies have shown significant structural and functional changes in regions of the interoceptive network, while molecular and genetic studies have revealed significant associations between interoceptive signaling and deficits in excitatory neurotransmission, altered endocrine and immune physiological pathways, and aberrant expression of transient receptor potential channel genes. Finally, there were emerging data suggesting that interoception-based interventions may reduce physical symptoms and improve quality of life and should be integrated into FGID clinical management practices.

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.

Interoception in anxiety, depression, and psychosis: a review

Research has examined the relationship between interoception and anxiety, depression, and psychosis; however, it is unclear which aspects of interoception have been systematically examined, what the combined findings are, and which areas require further research. To answer these questions, we systematically searched and narratively synthesised relevant reviews, meta-analyses, and theory papers (total n = 34). Existing systematic reviews and meta-analyses (anxiety n = 2; depression n = 2; psychosis n = 0), focus on cardiac interoceptive accuracy (heartbeat perception), and indicate that heartbeat perception is not systematically impaired in anxiety or depression. Heartbeat perception might be poorer in people with psychosis, but further evidence is needed. Other aspects of interoception, such as different body systems and processing levels, have been studied but not systematically reviewed. We highlight studies examining these alternative bodily domains and levels, review the efficacy of interoception-based psychological interventions, and make suggestions for future research.

Funding

Wellcome Trust UK.

Maternal interoceptive focus is associated with greater reported engagement in mother-infant stroking and rocking

Parental caregiving during infancy is primarily aimed at the regulation of infants' physiological and emotional states. Recent models of embodied cognition propose that interoception, i.e., the perception of internal bodily states, may influence the quality and quantity of parent-infant caregiving. Yet, empirical investigations into this relationship remain scarce. Across two online studies of mothers with 6- to 18-month-old infants during Covid-19 lockdowns, we examined whether mothers' self-reported engagement in stroking and rocking their infant was related to self-reported interoceptive abilities. Additional measures included retrospective accounts of pregnancy and postnatal body satisfaction, and mothers' reports of their infant's understanding of vocabulary relating to body parts. In Study 1 (N = 151) and Study 2 (N = 111), mothers reported their engagement in caregiving behaviours and their tendency to focus on and regulate bodily states. In a subsample from Study 2 (N = 49), we also obtained an objective measure of cardiac interoceptive accuracy using an online heartbeat counting task. Across both studies, the tendency to focus on and regulate interoceptive states was associated with greater mother-infant stroking and rocking. Conversely, we found no evidence for a relationship between objective interoceptive accuracy and caregiving. The findings suggest that interoception may play a role in parental engagement in stroking and rocking, however, in-person dyadic studies are warranted to further investigate this relationship.

Delving into the relationship between regular physical exercise and cardiac interoception in two cross-sectional studies

Cardiac interoception, the ability to sense and process cardiac afferent signals, has been shown to improve after a single session of acute physical exercise. However, it remains unclear whether repetitive engagement in physical exercise over time leads to long-term changes in cardiac interoceptive accuracy. It is also unknown whether those changes affect the neural activity associated with the processing of afferent cardiac signals, assessed by the heart-evoked potential (HEP). In this study, we aimed to investigate this hypothesis through two cross-sectional studies, categorizing participants as active or inactive based on physical fitness (Study I; N = 45) or self-reported physical activity levels (Study II; N = 60). Interoception was assessed at rest using the HEP (Studies I and II), the Heartbeat Counting task (Study II), and the Rubber Hand Illusion (RHI) (Study II). Study I showed strong evidence of better cardiovascular fitness in the active group than in the inactive group as well as robust between-group differences in electrocardiogram (ECG) recordings. Study 2 replicated the clear differences in ECG as a function of regular physical activity. Those results were expected due to clear differences in physical activity habits. In contrast, our analysis revealed no robust differences between groups across cardiac interoception tasks and the RHI, although the direct relevance of these measures to interoception remains under investigation. In sum, our results do not provide convincing evidence to support a strong version of the notion that regular physical exercise is associated with an enhanced in cardiac interoception.