Gastric interoception and gastric myoelectrical activity in bulimia nervosa and binge-eating disorder.

OBJECTIVE: Identifying factors that control food intake is crucial to the understanding and treatment of eating disorders characterized by binge eating. In healthy individuals, stomach distension plays an important role in the development of satiation, but gastric sensations might be overridden in binge eating. The present study investigated the perception of gastric signals (i.e., gastric interoception) and gastric motility in patients experiencing binge-eating episodes, that is, bulimia nervosa (BN) and binge-eating disorder (BED). METHOD: Twenty-nine patients with BN or BED (ED group) and 32 age-, sex-, and BMI-matched healthy controls (HC group) participated in the study. The onset of satiation and stomach fullness were assessed using a novel 2-step water load test (WLT-II). Gastric myoelectrical activity (GMA) was measured by electrogastrography (EGG) before and after ingestion of noncaloric water. RESULTS: Individuals in the ED group drank significantly more water until reporting satiation during the WLT-II. The percentage of normal gastric myoelectrical power was significantly smaller in the ED group compared to HC, and negatively related to the number of objective binge-eating episodes per week in patients with BN or BED. Power in the bradygastria range was greater in ED than in HC participants. DISCUSSION: Patients with EDs have a delayed response to satiation compared to HC participants, together with abnormal GMA. Repeated binge-eating episodes may induce disturbances to gastric motor function.

Internal states and interoception along a spectrum of eating disorder symptomology.

OBJECTIVE: Recent studies on atypical interoceptive capabilities have focused on clinical populations, including anorexia nervosa[1,2]. The present exploratory study aims to characterize the influence of disordered eating symptomology on interoceptive capabilities in college students, a population for which dangerous dieting behaviors may emerge. METHOD: Ninety-nine participants were randomized to consume a blinded high calorie or low calorie midday shake. Participants reported frequency of eating disorder cognitions and behaviors; indicated changes in satiety, happiness, and energy pre- and post-consumption; and guessed the calories in their shake. Outcomes (perceived satiety, changes in mood, and caloric guess) were regressed on eating disorder symptoms scores, the high/low calorie shake condition, and the interaction between these predictors. RESULTS: Those randomized to receive the high calorie shake reported feeling fuller, but only when endorsing lower levels of eating concern. Those randomized to the high calorie shake reported greater post-meal happiness, but only at greater levels of eating concerns. Lastly, those with lower levels of eating restraint reported an expected positive association between level of fullness and calorie guess, but those with higher levels of eating restraint did not exhibit any relationship between perceived fullness and calorie guess. DISCUSSION: Results of this exploratory suggest that irregular eating habits (e.g., not eating a sufficient amount for lunch) may have direct consequences on interoceptive capabilities. Further, these capacities may be impacted by individual differences in eating concern and restraint. Preliminary findings suggest that impairment in deciphering visceral signals may be associated with the degree of eating disorder symptomology; such impairment may occur at lower levels of symptomatology than normative data would indicate.

Preoccupied with the body: mild stress amplifies the relation between rumination and interoception.

Classic and modern emotion theories suggest that the perception of bodily sensations, or interoception, is foundational to emotion processing. The present research examined whether interoception is enhanced among people high in ruminative tendencies, especially under stress. To test this notion, the present research examined the effects of a mild stressor on subjective and objective measures of interoception among people varying in ruminative tendencies. Under conditions of mild stress, rumination was positively associated with self-reported private body consciousness -a marker of interoceptive sensibility- in Study 1 (N = 312) and with heartbeat detection accuracy (especially in the presence of auditory interference) in Study 2 (N = 180). In both studies, rumination was not significantly associated with interoceptive sensibility or accuracy in the absence of stress. These findings suggest that stress-induced amplification of bodily sensations may be important in explaining emotional dysregulation among chronic ruminators.

Comment on "Zamariola et al. (2018), Interoceptive Accuracy Scores are Problematic: Evidence from Simple Bivariate Correlations"-The empirical data base, the conceptual reasoning and the analysis behind this statement are misconceived and do not support the authors' conclusions.

A recent paper by Zamariola and colleagues is widely cited as an authority on the invalidity of the Heartbeat Counting Task as a measure of interoceptive accuracy. Given the widespread interest in this field, it is essential that papers about methods are conceptually sound. However, only one of the authors' four criticisms appears substantiated - that people count too few heartbeats. Their arguments about "simple bivariate correlations" and their finding that interoceptive accuracy and heart rate correlate, depend on 'spurious correlations' arising from the overlooked point that interoceptive accuracy is a ratio. Moreover, scrutiny of the authors' data shows that their fourth criticism (that interoceptive accuracy is lower on longer trials) is confounded by differences in mean heart rate between trials. We present data from our own labs to refute it. We draw the authors' and editors' attention to these issues and trust that they will reconsider these erroneous conclusions.

Investigating Multidimensional Interoceptive Awareness in a Japanese Population: Validation of the Japanese MAIA-J.

The Multidimensional Assessment of Interoceptive Awareness (MAIA) is a self-report instrument to assess relevant dimensions of bodily awareness. The aim of this study was to offer a Japanese version and adaptation of the MAIA (MAIA-J), as well as to analyse its psychometric properties in a Japanese population. The English MAIA was systematically forward and backward translated by bi-lingual Japanese experts; additionally, content validity aspects regarding language were discussed by a panel of experts. The MAIA-J was administered to 390 Japanese young adults (age: 20.3 ± 2.2), 67.7% women and 32.2% men. Exploratory factor analysis (EFA) reduced the questionnaire from 32 to 25 items and from 8 to 6 factors (Noticing, Not-Distracting, Attention Regulation, Emotional Awareness, Body Listening, and Trusting). The Japanese version showed appropriate indicators of construct validity and reliability, with Cronbach's α between 0.67 and 0.87 for the 6 MAIA-J dimensions. The findings demonstrate that MAIA-J has a slightly different factor structure compared to the original English MAIA. Results are discussed with respect to cultural differences. However, the study results support acceptable reliability of the MAIA-J in the Japanese sample, warranting its use for future studies with Japanese populations.

Atypical Self-Focus Effect on Interoceptive Accuracy in Anorexia Nervosa.

Background: Interoceptive abilities are known to be affected in anorexia nervosa (AN). Previous studies could show that private self-focus can enhance interoceptive accuracy (IAcc) in healthy participants. As body dissatisfaction is high in AN, confrontation with bodily features such as the own face might have a directly opposed effect in AN. Whether patients with AN can benefit from self-focus in their IAcc and whether this pattern changes over the time-course of cognitive behavioral therapy was investigated in this study. Methods: Fifteen patients with AN from the Psychosomatic Clinic in Windach were assessed three times in the time course of a standardized cognitive-behavioral therapy. They were compared to 15 controls, recruited from Ulm University and tested in a comparable setting. Both groups performed the heartbeat perception task assessing IAcc under two conditions either enhancing ("Self") or decreasing ("Other") self-focused attention. Furthermore, body dissatisfaction was assessed by a subscale of the Eating Disorder (ED) Inventory 2. Results: Patients with AN scored higher in IAcc when watching others' faces as compared to one's own face while performing the heartbeat perception task. The opposite pattern was observed in controls. IAcc remained reduced in AN as compared to controls in the time-course of cognitive-behavioral therapy, while body-dissatisfaction improved in AN. High body dissatisfaction was related to poorer IAcc in the "Self" condition. Conclusions: Our findings suggest that using self-focused attention reduces IAcc in AN while the opposite pattern was observed in controls. Confronting anorexic patients with bodily features might increase body-related avoidance and therefore decrease IAcc. The current study introduces a new perspective concerning the role of interoceptive processes in AN and generates further questions regarding the therapeutic utility of methods targeting self-focus in the treatment of AN.

The Water Load Test As a Measure of Gastric Interoception: Development of a Two-Stage Protocol and Application to a Healthy Female Population.

The sensitivity for one's own internal body signals (i.e., interoception) has been demonstrated to play an important role in the pathogenesis of eating and weight disorders. Most previous measures assessing interoceptive processing have not, or only partly, captured perception of hunger and satiety cues, which is a core aspect of interoceptive deficits in eating disorders. In addition, methods used to measure sensitivity to gastric signals are heterogeneous and findings inconsistent. The primary aim of the present study was to establish a standardised test to measure gastric interoception, and to provide normative data using a non-clinical adult sample. The two-step Water Load Test (WLT-II) involves ingestion of non-caloric water until perceived satiation (step 1) and until maximum fullness (step 2). The WLT-II consists of several variables: Besides volumes of water ingested until satiation and maximum fullness expressed in ml, percentage of satiation to maximum fullness is calculated as an individual index of gastric interoception that is not confounded with stomach capacity. Ninety-nine healthy women participated in the study. Measures included the WLT-II, the heartbeat tracking test, a self-report questionnaire assessing subjective sensations, and the Eating Disorder Inventory-2. Twenty-eight participants underwent test-retest of the WLT-II. Results suggest that the WLT-II is a valid and reliable measure of gastric interoception. Importantly, satiation volume and percentage of satiation to maximum fullness were strongly positively related to self-reported bulimic symptoms, indicating that the WLT-II could emerge as a useful clinical tool to measure interoceptive processing in the field of eating disorders.

German version of the intuitive eating scale: Psychometric evaluation and application to an eating disordered population.

Intuitive eating has been described to represent an adaptive eating behaviour that is characterised by eating in response to physiological hunger and satiety cues, rather than situational and emotional stimuli. The Intuitive Eating Scale-2 (IES-2) has been developed to measure such attitudes and behaviours on four subscales: unconditional permission to eat (UPE), eating for physical rather than emotional reasons (EPR), reliance on internal hunger and satiety cues (RHSC), and body-food choice congruence (B-FCC). The present study aimed at validating the psychometric properties of the German translation of the IES-2 in a large German-speaking sample. A second objective was to assess levels of intuitive eating in participants with an eating disorder diagnosis (anorexia nervosa, bulimia nervosa, or binge eating disorder). The proposed factor structure of the IES-2 could be confirmed for the German translation of the questionnaire. The total score and most subscale scores were negatively related to eating disorder symptomatology, problems in appetite and emotional awareness, body dissatisfaction, and self-objectification. Women with eating disorders had significantly lower values on all IES-2 subscale scores and the total score than women without an eating disorder diagnosis. Women with a binge eating disorder (BED) diagnosis had higher scores on the UPE subscale compared to participants with anorexia nervosa (AN) or bulimia nervosa (BN), and those diagnosed with AN had higher scores on the EPR subscale than individuals with BN or BED. We conclude that the German IES-2 constitutes a useful self-report instrument for the assessment of intuitive eating in German-speaking samples. Further studies are warranted to evaluate psychometric properties of the IES-2 in different samples, and to investigate its application in a clinical setting.

Changes in interoceptive processes following brain stimulation.

The processing and perception of individual internal bodily signals (interoception) has been differentiated to comprise different levels and processes involved. The so-called heartbeat-evoked potential (HEP) offers an additional possibility to examine automatic processing of cardiac signals. Knowledge on neural structures potentially supporting different facets of interoception is still sparse. One way to get insights into neuroanatomical function is to manipulate the activity of different brain structures. In this study, we used repetitive transcranial magnetic stimulation (rTMS) and a continuous theta-burst protocol to inhibit specific central locations of the interoceptive network including the right anterior insula and the right somatosensory cortices and assessed effects on interoceptive facets and the HEP in 18 male participants. Main results were that inhibiting anterior insula resulted in a significant decline in cardiac and respiratory interoceptive accuracy (IAc) and in a consistent decrease in perception confidence. Continuous theta-burst stimulation (cTBS) over somatosensory cortices reduced only cardiac IAc and affected perception confidence. Inhibiting right anterior insula and right somatosensory cortices increased interoceptive sensibility and reduced the HEP amplitude over frontocentral locations. Our findings strongly suggest that cTBS is an effective tool to investigate the neural network supporting interoceptive processes.This article is part of the themed issue 'Interoception beyond homeostasis: affect, cognition and mental health'.

Electrophysiological evidence for an attentional bias in processing body stimuli in bulimia nervosa.

Empirical evidence suggests abnormalities in the processing of body stimuli in bulimia nervosa (BN). This study investigated central markers of processing body stimuli by means of event-related potentials in BN. EEG was recorded from 20 women with BN and 20 matched healthy controls while watching and evaluating underweight, normal and overweight female body pictures. Bulimics evaluated underweight bodies as less unpleasant and overweight bodies as bigger and more arousing. A higher P2 to overweight stimuli occurred in BN only. In contrast to controls, no N2 increase to underweight bodies was observed in BN. P3 was modulated by stimulus category only in healthy controls; late slow waves to underweight bodies were more pronounced in both groups. P2 amplitudes to overweight stimuli were correlated with drive for thinness and body dissatisfaction. We present novel support for altered perceptual and cognitive-affective processing of body images in BN on the subjective and electrophysiological level.

Attenuated interoceptive sensitivity in overweight and obese individuals.

OBJECTIVE: Perceiving internal signals of hunger and satiety is related to the regulation of food intake. Recent data suggest that interoception (perception of bodily signals) and interoceptive sensitivity (sensitivity for internal signals) might be a crucial variable for the regulation of behavior associated with feelings of satiety. It is yet unclear whether interoceptive sensitivity is altered in overweight and obese participants. DESIGN AND METHODS: We therefore examined interoceptive sensitivity among 75 overweight and obese women and men using a heartbeat detection task and compared them to normal weight controls. We hypothesized that overweight and obesity would be related to attenuated interoceptive sensitivity. RESULTS: Interoceptive sensitivity was higher in normal weight participants as compared to overweight and obese participants. Additionally, we found a negative correlation coefficient between the BMI and interoceptive sensitivity in the overweight and obese group only. CONCLUSIONS: In accordance with our hypotheses, we found evidence for reduced interoceptive sensitivity in overweight and obese individuals. Interoceptive sensitivity presumably interacts with the regulation of food intake in everyday life in part by facilitating the detection of bodily changes accompanying satiety. Overweight and obese individuals might experience greater difficulties in accurately detecting such signals due to reduced interoceptive sensitivity.

Startling sweet temptations: hedonic chocolate deprivation modulates experience, eating behavior, and eyeblink startle.

Many individuals restrict their food intake to prevent weight gain. This restriction has both homeostatic and hedonic effects but their relative contribution is currently unclear. To isolate hedonic effects of food restriction, we exposed regular chocolate eaters to one week of chocolate deprivation but otherwise regular eating. Before and after this hedonic deprivation, participants viewed images of chocolate and images of high-calorie but non-chocolate containing foods, while experiential, behavioral and eyeblink startle responses were measured. Compared to satiety, hedonic deprivation triggered increased chocolate wanting, liking, and chocolate consumption but also feelings of frustration and startle potentiation during the intertrial intervals. Deprivation was further characterized by startle inhibition during both chocolate and food images relative to the intertrial intervals. Individuals who responded with frustration to the manipulation and those who scored high on a questionnaire of impulsivity showed more relative startle inhibition. The results reveal the profound effects of hedonic deprivation on experiential, behavioral and attentional/appetitive response systems and underscore the role of individual differences and state variables for startle modulation. Implications for dieting research and practice as well as for eating and weight disorders are discussed.

Eat your troubles away: electrocortical and experiential correlates of food image processing are related to emotional eating style and emotional state.

Emotional eating, a trait-like style of food intake in response to negative emotion states, represents an important aspect of overeating and eating related psychopathology. The mechanisms of emotional eating both on experiential and neuronal levels are not well delineated. We recorded event related potentials (ERPs) while individuals with high or low emotional eating style (HEE, n=25; LEE, n=20) viewed and rated pictures of high-caloric food during neutral state vs. negative idiosyncratic emotion induction. Craving ratings increased in HEE and decreased in LEE during negative relative to neutral states. ERPs to food pictures showed an enhanced late positive potential (LPP) over parieto-occipital regions for HEE compared to LEE. Emotional state modulated food picture evoked ERPs over right frontal regions in HEE only. This suggests that appetitive food processing is susceptible to both concurrent emotion and habitual eating style which is of relevance for overeating in healthy and abnormal eating.

Differential changes in self-reported aspects of interoceptive awareness through 3 months of contemplative training.

Interoceptive body awareness (IA) is crucial for psychological well-being and plays an important role in many contemplative traditions. However, until recently, standardized self-report measures of IA were scarce, not comprehensive, and the effects of interoceptive training on such measures were largely unknown. The Multidimensional Assessment of Interoceptive Awareness (MAIA) questionnaire measures IA with eight different scales. In the current study, we investigated whether and how these different aspects of IA are influenced by a 3-months contemplative intervention in the context of the ReSource project, in which 148 subjects engaged in daily practices of "Body Scan" and "Breath Meditation." We developed a German version of the MAIA and tested it in a large and diverse sample (n = 1,076). Internal consistencies were similar to the English version (0.56-0.89), retest reliability was high (rs: 0.66-0.79), and the MAIA showed good convergent and discriminant validity. Importantly, interoceptive training improved five out of eight aspects of IA, compared to a retest control group. Participants with low IA scores at baseline showed the biggest changes. Whereas practice duration only weakly predicted individual differences in change, self-reported liking of the practices and degree of integration into daily life predicted changes on most scales. Interestingly, the magnitude of observed changes varied across scales. The strongest changes were observed for the regulatory aspects of IA, that is, how the body is used for self-regulation in daily life. No significant changes were observed for the Noticing aspect (becoming aware of bodily changes), which is the aspect that is predominantly assessed in other IA measures. This differential pattern underscores the importance to assess IA multi-dimensionally, particularly when interested in enhancement of IA through contemplative practice or other mind-body interventions.

Sensitivity and specificity of hypnosis effects on gastric myoelectrical activity.

OBJECTIVES: The effects of hypnosis on physiological (gastrointestinal) functions are incompletely understood, and it is unknown whether they are hypnosis-specific and gut-specific, or simply unspecific effects of relaxation. DESIGN: Sixty-two healthy female volunteers were randomly assigned to either a single session of hypnotic suggestion of ingesting an appetizing meal and an unappetizing meal, or to relax and concentrate on having an appetizing or unappetizing meal, while the electrogastrogram (EGG) was recorded. At the end of the session, participants drank water until they felt full, in order to detect EGG-signal changes after ingestion of a true gastric load. During both conditions participants reported their subjective well-being, hunger and disgust at several time points. RESULTS: Imagining eating food induced subjective feelings of hunger and disgust as well as changes in the EGG similar to, but more pronounced than those seen with a real gastric water load during both hypnosis and relaxation conditions. These effects were more pronounced when imagining an appetizing meal than with an unappetizing meal. There was no significant difference between the hypnosis and relaxation conditions. CONCLUSION: Imagination with and without hypnosis exhibits similar changes in subjective and objective measures in response to imagining an appetizing and an unappetizing food, indicating high sensitivity but low specificity.

Intuitive eating is associated with interoceptive sensitivity. Effects on body mass index.

Intuitive eating is relevant for adaptive eating, body weight and well-being and impairments are associated with dieting and eating disorders. It is assumed to depend on the ability to recognize one's signs of hunger and fullness and to eat accordingly. This suggests a link to the individual ability to perceive and processes bodily signals (interoceptive sensitivity, IS) which has been shown to be associated with emotion processing and behavior regulation. This study was designed to clarify the relationships between IS as measured by a heartbeat perception task, intuitive eating and body mass index (BMI) in N=111 healthy young women. Intuitive eating was assessed by the Intuitive Eating Scale (IES) with three facets, reliance on internal hunger and satiety cues (RIH), eating for physical rather than emotional reasons (EPR), and unconditional permission to eat when hungry (UPE). IS was not only positively related to total IES score and RIH and EPR, and negatively predicted BMI, but also proved to fully mediate the negative relationship between RIH, as well as EPR and BMI. Additionally, the subjective appraisal of one's interoceptive signals independently predicted EPR and BMI. IS represents a promising mechanism in research on eating behavior and body weight.

On the embodiment of emotion regulation: interoceptive awareness facilitates reappraisal.

The ability to cognitively regulate emotional responses to aversive events is essential for mental and physical health. One prerequisite of successful emotion regulation is the awareness of emotional states, which in turn is associated with the awareness of bodily signals [interoceptive awareness (IA)]. This study investigated the neural dynamics of reappraisal of emotional responses in 28 participants who differed with respect to IA. Electroencephalography was used to characterize the time course of emotion regulation. We found that reappraisal was accompanied by reduced arousal and significant modulation of late neural responses. What is more, higher IA facilitated downregulation of affect and was associated with more pronounced modulation of underlying neural activity. Therefore, we conclude that IA not only advances the consolidation of somatic markers required for guiding individual behaviour but also creates processing advantages in tasks referring to these bodily markers.

Interoception across modalities: on the relationship between cardiac awareness and the sensitivity for gastric functions.

The individual sensitivity for ones internal bodily signals ("interoceptive awareness") has been shown to be of relevance for a broad range of cognitive and affective functions. Interoceptive awareness has been primarily assessed via measuring the sensitivity for ones cardiac signals ("cardiac awareness") which can be non-invasively measured by heartbeat perception tasks. It is an open question whether cardiac awareness is related to the sensitivity for other bodily, visceral functions. This study investigated the relationship between cardiac awareness and the sensitivity for gastric functions in healthy female persons by using non-invasive methods. Heartbeat perception as a measure for cardiac awareness was assessed by a heartbeat tracking task and gastric sensitivity was assessed by a water load test. Gastric myoelectrical activity was measured by electrogastrography (EGG) and subjective feelings of fullness, valence, arousal and nausea were assessed. The results show that cardiac awareness was inversely correlated with ingested water volume and with normogastric activity after water load. However, persons with good and poor cardiac awareness did not differ in their subjective ratings of fullness, nausea and affective feelings after drinking. This suggests that good heartbeat perceivers ingested less water because they subjectively felt more intense signals of fullness during this lower amount of water intake compared to poor heartbeat perceivers who ingested more water until feeling the same signs of fullness. These findings demonstrate that cardiac awareness is related to greater sensitivity for gastric functions, suggesting that there is a general sensitivity for interoceptive processes across the gastric and cardiac modality.

The body in the mind: on the relationship between interoception and embodiment.

The processing, representation, and perception of bodily signals (interoception) plays an important role for human behavior. Theories of embodied cognition hold that higher cognitive processes operate on perceptual symbols and that concept use involves reactivations of the sensory-motor states that occur during experience with the world. Similarly, activation of interoceptive representations and meta-representations of bodily signals supporting interoceptive awareness are profoundly associated with emotional experience and cognitive functions. This article gives an overview over present findings and models on interoception and mechanisms of embodiment and highlights its relevance for disorders that are suggested to represent a translation deficit of bodily states into subjective feelings and self-awareness.

Effects of short-term food deprivation on interoceptive awareness, feelings and autonomic cardiac activity.

The perception of internal bodily signals (interoception) plays a relevant role for emotion processing and feelings. This study investigated changes of interoceptive awareness and cardiac autonomic activity induced by short-term food deprivation and its relationship to hunger and affective experience. 20 healthy women were exposed to 24h of food deprivation in a controlled setting. Interoceptive awareness was assessed by using a heartbeat tracking task. Felt hunger, cardiac autonomic activity, mood and subjective appraisal of interoceptive sensations were assessed before and after fasting. Results show that short-term fasting intensifies interoceptive awareness, not restricted to food cues, via changes of autonomic cardiac and/or cardiodynamic activity. The increase of interoceptive awareness was positively related to felt hunger. Additionally, the results demonstrate the role of cardiac vagal activity as a potential index of emotion related self-regulation, for hunger, mood and the affective appraisal of interoceptive signals during acute fasting.