The relationship between subjective difficulty in interoceptive processing and accuracy of heartbeat perception in autistic individuals

Most autistic people experience difficulties in sensory processing, including interoceptive processing. For example, they often report subjective difficulties in the interoceptive processing of interoceptive input, such as difficulty in interpreting bodily signals, including hunger, thirst, and fatigue. However, whether these subjective interoceptive difficulties are from underlying problems in interoceptive accuracy remains unclear. This study investigated the relationship between subjective interoceptive difficulty and behavioral interoceptive accuracy in autistic adults and a control group. Subjective interoceptive accuracy was measured using an interoceptive sensitivity questionnaire, and behavioral interoceptive accuracy was measured using a heartbeat counting task. The results showed no significant relationship between subjective interoceptive difficulty and behavioral interoceptive accuracy in the autistic or control groups. This suggests that subjective interoceptive difficulty and behavioral interoceptive accuracy reflect different aspects of interoceptive processing. One possible interpretation is that autistic adults can identify individual local sensory inputs, such as heartbeats, however, they have difficulty integrating multiple inputs and recognizing internal body states such as hunger and fatigue.

"There's No Separating My View of My Body from My Autism": A qualitative study of positive body image in autistic individuals

While scholars have investigated positive body image across diverse populations, extant theory largely excludes those with differing socio-cognitive experiences, such as autistic individuals. Using constructivist grounded theory, this study sought to develop a grounded theory of positive body image in autistic individuals. One-to-one interviews with photo-elicitation were conducted with 20 autistic adults (7 women, 8 men, 5 non-binary/agender; aged 18-53 years) from the United Kingdom. Through a process of open, axial, and focused coding, a grounded theory was developed around a core category of positive body image in autistic adults and was found to comprise six themes: body connection, body acceptance, appreciating body functionality and neurodivergent strengths, having a body-positive protective filter, taking care of the body, and body and appearance neutrality. Our findings suggest that some aspects of positive body image in autistic individuals are consistent with those found in neurotypical adults. However, positive body image in autistic individuals further encompasses both the sensory (i.e., how the body is felt) and aesthetic (i.e., how the body is seen) body. These findings may stimulate research aimed at improving positive body image in autistic populations.

Recognition of others' interoceptive states in those with and without eating disorders

BACKGROUND

The ability to recognize one's own emotions is associated with one's ability to recognize others' emotions. Beyond the domain of emotion, however, the relationship between recognition of one's own internal states (interoception) and others' interoceptive states has not been investigated, either in the typical population or clinical groups with interoceptive difficulties (e.g. eating disorders; EDs).

METHOD

This study investigated recognition of one's own and others' internal states in adults with and without eating disorders, using a high frequency visual noise paradigm. Participants completed self-report measures of interoception, alexithymia (difficulties recognising one's own emotional internal states) and ED symptomatology, and the Heartbeat Counting Task measure of cardiac interoceptive accuracy.

RESULTS

Alexithymia was significantly negatively correlated with recognition of others' interoceptive states. EDs were not associated with difficulties recognising others' interoceptive states.

CONCLUSIONS

The ability to recognise one's own emotional internal states is associated with the recognition of others' interoceptive states, which may contribute to social skills and the ability to care for others.

Challenges and opportunities for conceptualizing intuitive eating in autistic people

Although intuitive eating (IE) has become an increasingly adopted intervention target, current conceptualisations of IE have yet to pivot away from (neuro)normative physiology and phenomenology. Autistic individuals commonly report disordered eating behaviours and/or poorer well-being but appear to benefit from adaptive interventions using an affirmative approach. This article uses autism as a case example to summarise challenges related to IE's prevailing conceptualisation, before proposing how future research and current practice can be extended to the autistic population. Scholars are encouraged to evaluate the full 10-principal IE framework while utilising a participatory-led approach. We argue that research using a mixed methods design is urgently needed to comprehensively explore the (re)conceptualisation of IE in autistic people. While IE shows promise for producing positive outcomes in the autistic population, we discuss the potential challenges for research and practice due to its current emphasis on accurate interoception, emotional awareness and processing, and executive functioning. This suggests the need for research and practice to integrate autistic needs and experiences into future developments with an affirmative approach. Public Significance: IE is an effective intervention for reducing disordered eating behaviours. Autistic individuals commonly present disordered eating behaviours and have unique nutritional needs which often require intervention. However, there is limited understanding of IE among the autistic population. Research-informed definitions involving autistic perspectives will support translating the IE framework to this underrepresented population.

Non-autistic adults can recognize posed autistic facial expressions: Implications for internal representations of emotion

Autistic people report that their emotional expressions are sometimes misunderstood by non-autistic people. One explanation for these misunderstandings could be that the two neurotypes have different internal representations of emotion: Perhaps they have different expectations about what a facial expression showing a particular emotion looks like. In three well-powered studies with non-autistic college students in the United States (total N = 632), we investigated this possibility. In Study 1, participants recognized most facial expressions posed by autistic individuals more accurately than those posed by non-autistic individuals. Study 2 showed that one reason the autistic expressions were recognized more accurately was because they were better and more intense examples of the intended expressions than the non-autistic expressions. In Study 3, we used a set of expressions created by autistic and non-autistic individuals who could see their faces as they made the expressions, which could allow them to explicitly match the expression they produced with their internal representation of that emotional expression. Here, neither autistic expressions nor non-autistic expressions were consistently recognized more accurately. In short, these findings suggest that differences in internal representations of what emotional expressions look like are unlikely to play a major role in explaining why non-autistic people sometimes misunderstand the emotions autistic people are experiencing.

Overactivation of posterior insular, postcentral and temporal regions during preserved experience of envy in autism

Social emotions are critical to successfully navigate in a complex social world because they promote self-regulation of behaviour. Difficulties in social behaviour are at the core of autism spectrum disorder (ASD). However, social emotions and their neural correlates have been scarcely investigated in this population. In particular, the experience of envy has not been addressed in ASD despite involving neurocognitive processes crucially compromised in this condition. Here, we used an fMRI adapted version of a well-validated task to investigate the subjective experience of envy and its neural correlates in adults with ASD (n = 30) in comparison with neurotypical controls (n = 28). Results revealed that both groups reported similarly intense experience of envy in association with canonical activation in the anterior cingulate cortex and the anterior insula, among other regions. However, in participants with ASD, the experience of envy was accompanied by overactivation of the posterior insula, the postcentral gyrus and the posterior superior temporal gyrus, regions subserving the processing of painful experiences and mentalizing. This pattern of results suggests that individuals with ASD may use compensatory strategies based on the embodied amplification of pain and additional mentalizing efforts to shape their subjective experience of envy. Results have relevant implications to better understand the heterogeneity of this condition and to develop new intervention targets.

Autism Spectrum Disorder May Be Highly Prevalent in People with Functional Neurological Disorders

Recent observations suggest that autism spectrum disorder (ASD) co-occurs in people with a functional neurological disorder (FND), but little systematic data are available on the relationship between FND and autism. The study aimed to assess the self-reported autistic traits via a standardized questionnaire and the prevalence of previously diagnosed ASD among people with FND and their 1st-degree relatives. We performed a survey of members of the patient organization FNDHope, using a self-completed questionnaire for screening for autistic traits and ASD: the adult autism subthreshold spectrum (AdAS spectrum). There were 344 respondents diagnosed with FND with a mean age of 39.8 ± 11.6 years (female sex 90%). Eight per cent of respondents volunteered a previous diagnosis of ASD, and 24% reported a 1st-degree relative with a formal diagnosis of ASD, mostly their children. We found that 69% of respondents had scores in the AdAS spectrum indicating a clinically significant ASD and 21% indicating autistic traits. Further studies are needed to provide more evidence regarding the prevalence of ASD in people with FND and how this may influence the aetiology, treatment selection and prognosis.

Validation of the Japanese version of the Interoception Sensory Questionnaire for individuals with autism spectrum disorder

The Interoception Sensory Questionnaire (ISQ) is a self-report instrument used to assess the characteristics of interoceptive processing in individuals with autism spectrum disorder (ASD). Previous studies have shown that scores of the ISQ are more appropriate than other subjective measures for evaluating difficulties in interoceptive processing in individuals with ASD. Yet, no prior research has demonstrated the validation of the ISQ in Japanese samples. This study attempted to validate the Japanese version of the ISQ (ISQ-J) by examining its psychometric properties. We confirmed the score distribution, internal consistency, and factor structure in Japanese samples. We also examined the relationships with other interoceptive questionnaires. In addition, we compared the scores of the ISQ-J between adolescents and adults with ASD participants and control participants. Results of confirmatory factor analyses showed that the reliability of the ISQ-J in adults with ASD reached an acceptable level of a one-factor structure with excellent internal consistency (α = 0.963). The result of the ISQ-J showed a significant positive correlation with the measure of awareness of interoceptive sensitivity for localized bodily states; on the other hand, a significant negative correlation was found with those integrated bodily states. In addition, the ISQ-J scores were significantly higher in the ASD group than in the control group. The current findings depend on self-report data (including a diagnosis of ASD) to measure validity constructs. Additionally, since the ISQ-J was surveyed in adults with ASD, it is unclear whether similar the results would be obtained if the ISQ-J were conducted with children. These results indicate the validity and reliability of the ISQ-J and provide a tool for assessing confusion of interoceptive information in Japanese adults with ASD.

Alexithymia and intolerance of uncertainty predict somatic symptoms in autistic and non-autistic adults

LAY ABSTRACT

Autistic people have more physical health problems than non-autistic people. We were interested in whether autistic people experience more discomfort in their bodies than non-autistic people and whether certain psychological traits contribute to that. A survey was completed online by older adolescents and adults, 51 of whom were autistic, 32 of whom thought they might be autistic but were not diagnosed and 119 who were not autistic. They completed measures of somatic symptoms (daily experience of pain, discomfort, dizziness), alexithymia (difficulty identifying and expressing feelings), interoception (how much people are aware of their bodies) and intolerance of uncertainty (how people handle doubt or uncertainty), and reported any physical or mental health conditions. We found that the autistic participants had more physical and mental health conditions than the non-autistic participants, but even when we took account of this, they experienced higher levels of somatic symptoms. We looked at which psychological factors influenced levels of somatic symptoms across the whole sample, and found that alexithymia, intolerance of uncertainty, having physical health problems, being female and the number of mental health conditions predicted somatic symptoms, while interoception and autism diagnosis did not. The findings suggest that people may be more likely to experience physical discomfort if they are female, and have difficulty identifying and expressing feeling and difficulty tolerating doubt. As these psychological factors are more prominent in autism, we think this is important for physical and mental health providers to know about, so that these psychological factors can be considered when assessing and treating autistic people.

Development and validation of the Interoceptive States Static Images (ISSI) database

Internal bodily signals provide an essential function for human survival. Accurate recognition of such signals in the self, known as interoception, supports the maintenance of homeostasis, and is closely related to emotional processing, learning and decision-making, and mental health. While numerous studies have investigated interoception in the self, the recognition of these states in others has not been examined despite its crucial importance for successful social relationships. This paper presents the development and validation of the Interoceptive States Static Images (ISSI), introducing a validated database of 423 visual stimuli for the study of non-affective internal state recognition in others, freely available to other researchers. Actors were photographed expressing various exemplars of both interoceptive states and control actions. The images went through a two-stage validation procedure, the first involving free-labelling and the second using multiple choice labelling and quality rating scales. Five scores were calculated for each stimulus, providing information about the quality and specificity of the depiction, as well as the extent to which labels matched the intended state/action. Results demonstrated that control action stimuli were more recognisable than internal state stimuli. Inter-category variability was found for the internal states, with some states being more recognisable than others. Recommendations for the utilisation of ISSI stimuli are discussed. The stimulus set is freely available to researchers, alongside data concerning recognisability.

The Emerging Science of Interoception: Sensing, Integrating, Interpreting, and Regulating Signals within the Self

Interoception refers to the representation of the internal states of an organism, and includes the processes by which it senses, interprets, integrates, and regulates signals from within itself. This review presents a unified research framework and attempts to offer definitions for key terms to describe the processes involved in interoception. We elaborate on these definitions through illustrative research findings, and provide brief overviews of central aspects of interoception, including the anatomy and function of neural and non-neural pathways, diseases and disorders, manipulations and interventions, and predictive modeling. We conclude with discussions about major research gaps and challenges.

Exploring Social Biomarkers in High-Functioning Adults with Autism and Asperger's Versus Healthy Controls: A Cross-Sectional Analysis

Biomarkers for autism spectrum disorder (ASD) are lacking but would facilitate drug development for the core deficits of the disorder. We evaluated markers proposed for characterization of differences in social communication and interaction in adults with ASD versus healthy controls (HC) for utility as biomarkers. Data pooled from an observational study and baseline data from a placebo-controlled study were analyzed. Between-group differences were observed in eye-tracking tasks for activity monitoring, biomotion, human activity preference, composite score (p = 0.0001-0.037) and pupillometry (various tasks, p = 0.017-0.05). Impaired olfaction was more common in the ASD sample versus HC (p = 0.018). Our preliminary results suggest the potential use for stratification and response sub-analyses outcome-prediction of specific eye-tracking tasks, pupillometry and olfaction tests in ASD trials.

Systematic review and meta-analysis of the relationship between the heartbeat-evoked potential and interoception

The Heartbeat Evoked Potential (HEP) has been proposed as a neurophysiological marker of interoceptive processing. Despite its use to validate interoceptive measures and to assess interoceptive functioning in clinical groups, the empirical evidence for a relationship between HEP amplitude and interoceptive processing, including measures of such processing, is scattered across several studies with varied designs. The aim of this systematic review and meta-analysis was to examine the body of HEP-interoception research, and consider the associations the HEP shows with various direct and indirect measures of interoception, and how it is affected by manipulations of interoceptive processing. Specifically, we assessed the effect on HEP amplitude of manipulating attention to the heartbeat; manipulating participants' arousal; the association between the HEP and behavioural measures of cardiac interoception; and comparisons between healthy and clinical groups. Following database searches and screening, 45 studies were included in the systematic review and 42 in the meta-analyses. We noted variations in the ways individual studies have attempted to address key confounds, particularly the cardiac field artefact. Meta-analytic summaries indicated there were moderate to large effects of attention, arousal, and clinical status on the HEP, and a moderate association between HEP amplitude and behavioural measures of interoception. Problematically, the reliability of the meta-analytic effects documented here remain unknown, given the lack of standardised protocols for measuring the HEP. Thus, it is possible effects are driven by confounds such as cardiac factors or somatosensory effects.

Nutritional Deficiency Disease Secondary to ARFID Symptoms Associated with Autism and the Broad Autism Phenotype: A Qualitative Systematic Review of Case Reports and Case Series

BACKGROUND

The demographics, weight statuses, and dietary patterns of people with autism or the broad autism phenotype who experience a severe nutrient deficiency disease due to symptoms of avoidant/restrictive food intake disorder have not been well established.

OBJECTIVE

The primary objective of this review was to examine the relationship between the demographics, weight statuses, dietary patterns, and nutrient deficiency diseases that characterize the most severe manifestations of avoidant/restrictive food intake disorder symptomology associated with autism or the broad autism phenotype.

METHODS

A systematic review of English and non-English articles published up to August 29, 2019, on the Scopus, PubMed, and Cumulative Index to Nursing and Allied Health Literature Plus electronic databases was conducted. Additional cases were identified through the reference list of all included articles. The search terms used were "autis^∗ AND (deficiency OR scurvy)". Only case reports or case series in which a person of any age who had been identified as having a formal diagnosis of autism or autism symptoms and a disease of nutritional deficiency due to self-imposed dietary restrictions were included. Data were independently extracted by 8 authors using predefined data fields.

RESULTS

A total of 76 cases (patients were aged 2.5 to 17 years) from 63 articles that were published from 1993 through 2019 were found. More than 85% cases (65 of 76 patients) were from articles published in the past 10 years. The largest percentage of published cases (69.7% [53 of 76]) involved scurvy, a vitamin C deficiency. The second-largest percentage of published cases (17.1% [13 of 76]) involved eye disorders secondary to vitamin A deficiency. Other primary nutrient deficiencies reported were thiamin, vitamin B-12, and vitamin D. In 62.9% (22 of 35) of the patients for which a body mass index or a weight percentile for age was provided, the patient was within normal weight parameters, per Centers for Disease Control weight status categories.

CONCLUSIONS

Based on the 63 articles extracted for this systematic review, nutritional deficiency diseases related to inadequate intakes of vitamin A, thiamin, vitamin B-12, vitamin C, and vitamin D were found in individuals with autism and the broad autism phenotype who had severe self-imposed dietary restrictions. When weight information was provided, most of the youth in these cases were not reported to be underweight. Individuals of any weight who present with symptoms of avoidant/restrictive food intake disorder can benefit from early and frequent screening for adequacy of micronutrient intake, regardless of whether they have a clinical diagnosis of autism.

Interoception is Impaired in Children, But Not Adults, with Autism Spectrum Disorder

Interoception (the ability to sense what’s going on inside one’s body) is considered integral to many higher-order cognitive processes. Some have speculated that impaired interoception may underpin some features of ASD. Yet, in Experiment 1, we found no evidence of a between-group difference in either cardiac or respiratory interoceptive accuracy among 21 adults with ASD and 21 matched controls. Bayesian analyses suggested the data strongly supported the null hypothesis. In Experiment 2, we measured cardiac interoceptive accuracy in 21 children with ASD and 21 matched controls. Here interoceptve accuracy was significantly diminished in the ASD group and was associated with a moderate-to-large effect size. Results suggest early interoception difficulties are resolved or compensated for by adulthood in people with ASD.

Major Depressive Disorder Is Associated with Impaired Interoceptive Accuracy: A Systematic Review

Interoception is the sense of the physiological condition of the entire body. Impaired interoception has been associated with aberrant activity of the insula in major depressive disorder (MDD) during heartbeat perception tasks. Despite clinical relevance, studies investigating interoceptive impairments in MDD have never been reviewed systematically according to the guidelines of the PRISMA protocol, and therefore we collated studies that assessed accuracy in detecting heartbeat sensations (interoceptive accuracy, IAc) in MDD (databases: PubMed/Medline, PsycINFO, and PsycARTICLES). Out of 389 records, six studies met the inclusion criteria. The main findings suggest that (i) moderately depressed samples exhibit the largest interoceptive deficits as compared with healthy adults. (ii) difficulties in decision making and low affect intensity are correlated with low IAc, and (iii) IAc seems to normalize in severely depressed subjects. These associations may be confounded by sex, anxiety or panic disorder, and intake of selective serotonin reuptake inhibitors. Our findings have implications for the development of interoceptive treatments that might relieve MDD-related symptoms or prevent relapse in recurrent depression by targeting the interoceptive nervous system.

Being socially uninterested versus not having social prediction skills: The impact of multisensory integration deficits on social skills in autism

Jaswal & Akhtar in their target article convincingly argue that subjects with autism do not have diminished social motivation. However, they still recognize that autistic people behave socially in an unusual way. Why? Here we suggest that these behaviours are the results of a multisensory integration deficit. Viewed from this perspective, the assumption that autistic people's unusual behaviours indicate diminished social motivation has to be replaced by the one that they have diminished social prediction skills.

Interoceptive impairments do not lie at the heart of autism or alexithymia

Quattrocki and Friston (2014) argued that abnormalities in interoception—the process of representing one’s internal physiological states—could lie at the heart of autism, because of the critical role interoception plays in the ontogeny of social-affective processes. This proposal drew criticism from proponents of the alexithymia hypothesis, who argue that social-affective and underlying interoceptive impairments are not a feature of autism per se, but of alexithymia (a condition characterized by difficulties describing and identifying one’s own emotions), which commonly co-occurs with autism. Despite the importance of this debate for our understanding of autism spectrum disorder (ASD), and of the role of interoceptive impairments in psychopathology, more generally, direct empirical evidence is scarce and inconsistent. Experiment 1 examined in a sample of 137 neurotypical (NT) individuals the association among autistic traits, alexithymia, and interoceptive accuracy (IA) on a standard heartbeat-tracking measure of IA. In Experiment 2, IA was assessed in 46 adults with ASD (27 of whom had clinically significant alexithymia) and 48 NT adults. Experiment 1 confirmed strong associations between autistic traits and alexithymia, but yielded no evidence to suggest that either was associated with interoceptive difficulties. Similarly, Experiment 2 provided no evidence for interoceptive impairments in autistic adults, irrespective of any co-occurring alexithymia. Bayesian analyses consistently supported the null hypothesis. The observations pose a significant challenge to notions that interoceptive impairments constitute a core feature of either ASD or alexithymia, at least as far as the direct perception of interoceptive signals is concerned.

This article suggests that impairments in interoception—the process of representing one’s internal physiological states—do not lie at the heart of either autism or alexithymia.