Pain sensitivity in anorexia nervosa and bulimia nervosa

Endogenous opioid receptors and the feast or famine of maladaptive feeding

Maladaptive feeding comprises unhealthy eating patterns that jeopardize survival, including over- and underconsumption. These behaviors are often coordinated by endogenous opioid receptors (EORs). Here, we explore the involvement of EORs in obesity and anorexia nervosa (AN), two disorders associated with dysregulated feeding behavior and relevant animal models. While seemingly opposing metabo-psychiatric states, our goal is to highlight common circuit and synaptic mechanisms underlying obesity and AN with a focus on EOR functionality. We examine the neural substrates underlying maladaptive feeding and comorbid conditions including pain, suggesting a role for EOR-driven plasticity in the pathogenesis of both obesity and AN.

Evaluating the predictions of an interoceptive inference model of bulimia nervosa

OBJECTIVE

Bulimia nervosa (BN) is associated with loss-of-control (LOC) eating episodes that frequently occur in response to negative emotions. According to recent neurocomputational models, this link could be explained by a failure to accurately update beliefs about the body in states of high arousal. Specifically, these interoceptive inference models suggest that under-relying on signals from one's body about sensory experience ("low sensory precision") and/or over-relying on previously held beliefs ("excessively precise priors") lead to inaccurate perception and maladaptive behaviors. We conducted an initial test of these core predictions of the interoceptive inference model in BN using self-report measures.

METHODS

We compared women with BN (n = 30) and age-, BMI-, and full-scale IQ-matched controls (n = 31) on trust in sensory information from the body and two types of beliefs about what can be done to regulate high negative affect. Within the BN group, we tested interrelations among these measures and explored their associations with LOC eating frequency.

RESULTS

Compared with healthy controls, the BN group reported lower levels of trust in sensory information and stronger beliefs that once upset, there is little one can do, apart from eating, to self-regulate. These beliefs were associated with each other and with lower body trust. Beliefs about the uncontrollability of emotion were associated with more frequent subjective binge-eating episodes.

CONCLUSIONS

Findings provide initial support for the core predictions of an interoceptive inference account of BN: low trust in sensory information ("sensory precision") may promote an overreliance on maladaptive "prior beliefs" about the effects of eating on negative emotions, ultimately interfering with accurate updating of beliefs about other strategies that could regulate emotions and maintain LOC eating. Low body trust, strong expectations about emotions, and their neurocomputational underpinnings could be promising combined treatment targets for BN.

Perceptual Dysfunction in Eating Disorders

Eating disorders (EDs) are characterized by abnormal responses to food and weight-related stimuli and are associated with significant distress, impairment, and poor outcomes. Because many of the cardinal symptoms of EDs involve disturbances in perception of one's body or abnormal affective or cognitive reactions to food intake and how that affects one's size, there has been longstanding interest in characterizing alterations in sensory perception among differing ED diagnostic groups. Within the current review, we aimed to critically assess the existing research on exteroceptive and interoceptive perception and how sensory perception may influence ED behavior. Overall, existing research is most consistent regarding alterations in taste, visual, tactile, and gastric-specific interoceptive processing in EDs, with emerging work indicating elevated respiratory and cardiovascular sensitivity. However, this work is far from conclusive, with most studies unable to speak to the precise etiology of observed perceptual differences in these domains and disentangle these effects from affective and cognitive processes observed within EDs. Further, existing knowledge regarding perceptual disturbances in EDs is limited by heterogeneity in methodology, lack of multimodal assessment protocols, and inconsistent attention to different ED diagnoses. We propose several new avenues for improving neurobiology-informed research on sensory processing to generate actionable knowledge that can inform the development of innovative interventions for these serious disorders.

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.

The perception of affective and discriminative touch in blind individuals

Enhanced tactile acuity in blindness is among the most widely reported results of neuroplasticity following prolonged visual deprivation. However, tactile submodalities other than discriminative touch are profoundly understudied in blind individuals. Here, we examined the influence of blindness on two tactile submodalities, affective and discriminative touch, the former being vital for social functioning and emotional processing. We tested 36 blind individuals and 36 age- and sex-matched sighted volunteers. In Experiment 1, we measured the perception of affective tactile signals by asking participants to rate the pleasantness of touch delivered on the palm (nonhairy skin, sparsely innervated with C tactile [CT] fibers) or the forearm (hairy skin, densely innervated with CT fibers) in a CT-optimal versus a CT-nonoptimal manner using a paradigm grounded in studies on tactile sensory neurophysiology. In Experiment 2, we implemented a classic task assessing discriminative touch abilities, the grating orientation task. We found that blind individuals rated the touch as more pleasant when delivered on the palm than on the forearm, while the opposite pattern was observed for sighted participants, who rated stimulation on the forearm as more pleasant than stimulation on the palm. We also replicated the previous findings showing enhanced discriminative tactile acuity in blind individuals. Altogether, our results suggest that blind individuals might experience affective touch differently than sighted individuals, with relatively greater pleasantness perceived on the palm. These results provide a broader insight into somatosensory perception in blind individuals, for the first time taking into consideration the socioemotional aspect of touch.

Sensory processing in children and adolescents shortly after the onset of anorexia nervosa: a pilot study

BACKGROUND

Alterations in sensory processing, such as vision, taste, and interoceptive sensation, have been reported in adult anorexia nervosa (AN). Whether these symptoms are traits, states, or "scars" due to chronic starvation has not been fully established. Based on the hypothesis that alterations in sensory processing also occur in adolescent AN in the early stages of the disease, the present study was conducted using both self-administered and parent-administered sensory processing questionnaires.

METHODS

Children and adolescents with anorexia nervosa treated at a single tertiary eating disorder treatment center in Japan (AN group) and female junior high school students attending a public junior high school in Saitama Prefecture, Japan (healthy control group: HC group) were included in the study. The Sensory Profile (SP) and Adult/Adolescent Sensory Profile (AASP) were administered to the participants and their caregivers. In addition, we collected demographic data and administered the Children's Eating Attitude Test and Autism-Spectrum Quotient Children's version.

RESULTS

Seventeen children and adolescents were enrolled in the AN group, and 63 were enrolled in the HC group. There was no statistically significant difference between the AN and HC groups in the quadrant scores of the AASP. In the SP, the Sensory Avoiding score and the Emotional/Social response score were higher in the AN group than in the HC group.

CONCLUSION

From the parents' point of view, the patient avoids unexpected sensory stimuli, but the patients are unaware of their own avoiding behavior in the early stages of the disease. The results suggest that sensory sensitivity in AN may be a "scar" symptom due to chronic starvation and a state symptom. Longitudinal studies from shortly after the onset with larger sample sizes are needed to gain insight into the dynamic relation between sensory processing and eating disorder pathology.

From Virtual Reality to Regenerative Virtual Therapy: Some Insights from a Systematic Review Exploring Inner Body Perception in Anorexia and Bulimia Nervosa

Despite advances in our understanding of the behavioral and molecular factors that underlie the onset and maintenance of Eating Disorders (EDs), it is still necessary to optimize treatment strategies and establish their efficacy. In this context, over the past 25 years, Virtual Reality (VR) has provided creative treatments for a variety of ED symptoms, including body dissatisfaction, craving, and negative emotions. Recently, different researchers suggested that EDs may reflect a broader impairment in multisensory body integration, and a particular VR technique-VR body swapping-has been used to repair it, but with limited clinical results. In this paper, we use the results of a systematic review employing PRISMA guidelines that explore inner body perception in EDs (21 studies included), with the ultimate goal to analyze the features of multisensory impairment associated with this clinical condition and provide possible solutions. Deficits in interoception, proprioception, and vestibular signals were observed across Anorexia and Bulimia Nervosa, suggesting that: (a) alteration of inner body perception might be a crucial feature of EDs, even if further research is needed and; (b) VR, to be effective with these patients, has to simulate/modify both the external and the internal body. Following this outcome, we introduce a new therapeutic approach-Regenerative Virtual Therapy-that integrates VR with different technologies and clinical strategies to regenerate a faulty bodily experience by stimulating the multisensory brain mechanisms and promoting self-regenerative processes within the brain itself.

Headache, eating disorders, PTSD, and comorbidity: implications for assessment and treatment

PURPOSE

Severe headaches (HAs) have been associated with eating disorders (ED) as well as with trauma, posttraumatic stress disorder (PTSD), major depression and anxiety. However, data addressing all of these factors in the same subjects are limited.

METHODS

In a large sample of patients (n = 1461, 93% female) admitted to residential treatment (RT) for an ED, we assessed within 48-72 h of admission subjective reports of frequent HAs and their associations with severity of ED, PTSD, major depressive and state-trait anxiety symptoms, as well as quality of life measures. HA ratings were significantly correlated to the number of lifetime trauma types as well as to symptoms of PTSD, major depression, and state-trait anxiety.

RESULTS

Results indicated that 39% of patients endorsed that frequent HAs occurred "often" or "always" (HA+) in association with their eating or weight issues. This HA-positive (HA+) group had statistically significant higher numbers of lifetime trauma types, higher scores on measures of ED, PTSD, major depressive, and state-trait anxiety symptoms, and worse quality of life measures (p ≤ 0.001) in comparison to the HA-negative (HA-) group, who endorsed that frequent HAs occurred "never," "rarely," or "sometimes" in association with their eating or weight issues. The HA + group also had a significantly higher rate of a provisional PTSD diagnosis (64%) than the HA- group (35%) (p ≤ .001). Following comprehensive RT, HA frequency significantly improved (p ≤ .001).

CONCLUSION

These findings have important implications for the assessment and treatment of HAs in the context of ED, PTSD and related psychiatric comorbidities, especially at higher levels of care. In addition, the importance of identifying traumatic histories and treating comorbid PTSD and related psychopathology in individuals presenting with severe HAs is emphasized.

LEVEL OF EVIDENCE

III Evidence obtained from well-designed cohort or case-control analytic studies.

Interoceptive Awareness and Suicidal Ideation in a Clinical Eating Disorder Sample: The Role of Body Trust

Previous research has demonstrated that both suicidal ideation (SI) and eating disorders (EDs) are associated with poor interoceptive awareness (IA). Suicidality research has demonstrated that the IA dimension of lower body trust is associated with SI, suicide plans, and suicide attempts. Similarly, in ED samples, recent research supports that low body trust has been the most robust dimension of IA associated with eating pathology. However, to date, research is lacking in how dimensions of IA may be associated with SI in an ED sample, above and beyond the impact of eating pathology on SI. Thus, in a clinical ED sample, the present study sought to determine which IA dimensions predict the presence and severity of SI, above and beyond ED symptoms. Participants (N = 102) completed a clinical interview assessing SI and self-report assessments including the Multidimensional Assessment of Interoceptive Awareness (MAIA). Results demonstrated that patients with current SI reported greater ED psychopathology, lower MAIA Attention Regulation, MAIA Self-Regulation, and MAIA Trusting scores compared to patients without SI. Higher ED psychopathology and lower MAIA Attention Regulation, Self-Regulation, and Trusting subscale scores were all significantly associated with the presence of SI. However, only low MAIA Trusting scores predicted the presence of SI, above and beyond covariates (age, depression, and eating pathology). No MAIA subscales were correlated with the severity of SI. Consistent with previous research, results suggest low MAIA Trusting scores may be associated with SI in ED samples and highlight the need for future research on mechanisms of these associations.

Increased anticipatory brain response to pleasant touch in women remitted from bulimia nervosa

Bulimia nervosa (BN) is characterized by affective instability and dysregulated behaviors (binge eating, fasting, self-induced vomiting) that disrupt bodily homeostasis. Mechanisms underlying dysregulation in BN are unclear, although altered reward responsivity, anticipatory processing of environmental cues, and interoception (detection and integration of body-state signals to regulate behavior) have been implicated in BN pathophysiology. We aimed to determine whether BN is associated with ineffectively predicting body state or integrating predicted experience with actual experience by examining neural response to anticipation and experience of affective touch, a pleasant interoceptive stimulus that acts on sensory and emotional systems to guide behavior. During fMRI, we administered soft strokes to the palm and forearm in women remitted from BN (RBN; N = 23) and control women (CW; N = 25). A Group (RBN/CW) × Condition (anticipation/touch) interaction was found in the right dorsal caudate; both CW and RBN had increased activation during touch compared with anticipation, with RBN demonstrating marginally greater anticipatory response than CW. For RBN, those individuals who showed greater anticipatory response in the dorsal caudate also reported higher levels of harm avoidance. RBN individuals relative to CW showed greater activation in left putamen and insula during the anticipation but not when experiencing an affective touch. This increase during anticipation rather than the actual experience of the affective touch is consistent with a top-down preparatory process which is associated with harm avoidance and is similar to what has been observed in anxious individuals. This aberrant signal integration could disrupt feedback processing, serving to maintain disordered behavior.

Heightened affective response to perturbation of respiratory but not pain signals in eating, mood, and anxiety disorders

Several studies have recently suggested that an abnormal processing of respiratory interoceptive and nociceptive (painful) stimuli may contribute to eating disorder (ED) pathophysiology. Mood and anxiety disorders (MA) are also characterized by abnormal respiratory symptoms, and show substantial comorbidity with ED. However, no studies have examined both respiratory and pain processing simultaneously within ED and MA. The present study systematically evaluated responses to perturbations of respiratory and nociceptive signals across the levels of physiology, behavior, and symptom report in a transdiagnostic ED sample (n = 51) that was individually matched to MA individuals (n = 51) and healthy comparisons (HC; n = 51). Participants underwent an inspiratory breath-holding challenge as a probe of respiratory interoception and a cold pressor challenge as a probe of pain processing. We expected both clinical groups to report greater stress and fear in response to respiratory and nociceptive perturbation than HCs, in the absence of differential physiological and behavioral responses. During breath-holding, both the ED and MA groups reported significantly more stress, feelings of suffocation, and suffocation fear than HC, with the ED group reporting the most severe symptoms. Moreover, anxiety sensitivity was related to suffocation fear only in the ED group. The heightened affective responses in the current study occurred in the absence of group differences in behavioral (breath hold duration, cold pressor duration) and physiological (end-tidal carbon dioxide, end-tidal oxygen, heart rate, skin conductance) responses. Against our expectations, there were no group differences in the response to cold pain stimulation. A matched-subgroup analysis focusing on individuals with anorexia nervosa (n = 30) produced similar results. These findings underscore the presence of abnormal respiratory interoception in MA and suggest that hyperreactivity to respiratory signals may be a potentially overlooked clinical feature of ED.

Moving towards specificity: A systematic review of cue features associated with reward and punishment in anorexia nervosa

Models of anorexia nervosa (AN) posit that symptoms are maintained through deficient reward and enhanced punishment processing. However, theoretical and empirical inconsistencies highlight the need for a more nuanced conceptualization of this literature. Our goal was to comprehensively review the research on reward and punishment responding in AN from a cue-specific lens to determine which stimuli evoke or discourage reward and punishment responses in this population, and, ultimately, what properties these rewarding and punishing cues might share. A systematic review interrogating reward and punishment responses to specific cues yielded articles (n = 92) that examined responses to disorder relevant (e.g., food) and irrelevant (e.g., money) stimuli across self-report, behavioral, and biological indices. Overall, in most studies individuals with AN exhibited aversive responses to cues signaling higher body weights, social contexts, and monetary losses, and appetitive responses to cues for weight loss behaviors and thinness. Findings were more mixed on responses to palatable food and monetary gains. Results highlight that reward and punishment responding in AN are context specific and may be affected by varied stimulus qualities (e.g., predictability, controllability, delay, effort). Increasing specificity in future research on reward and punishment mechanisms in AN will better inform development of precisely-targeted interventions.

Altered anticipation and processing of aversive interoceptive experience among women remitted from bulimia nervosa

Bulimia nervosa (BN) is characterized by dysregulated intake of food, which may indicate homeostatic imbalance. Critically important for homeostatic regulation is interoception, or the sensing and processing of body-relevant information. A well-documented link between avoidance of unpleasant body sensations and BN symptoms suggests that aversive interoceptive experiences may be particularly relevant to BN pathophysiology. This study examined whether individuals with a history of BN show aberrant neural processing of aversive interoceptive stimuli. Using a cued inspiratory breathing load paradigm, we compared women remitted from BN (RBN; n = 24; to reduce the confounding effects of active bulimic symptoms) and control women (CW; n = 25). During breathing load anticipation, the RBN group, relative to CW, showed increased activation in mid-insula, superior frontal gyrus, putamen, dorsal anterior cingulate, posterior cingulate, and amygdala. However, over the course of the aversive experience, neural activation in RBN relative to CW showed an aberrant decline in most of these regions. Exploratory analyses indicated that greater activation during breathing load anticipation was associated with past bulimic symptom severity and the duration of symptom remission. An exaggerated anticipatory response and an abnormally decreasing response during aversive homeostatic perturbations may promote hallmark bulimic behaviors-binge eating, dietary restriction, and purging. Our findings support a role for homeostatic instability in BN, and these altered patterns of brain activation may serve as novel targets for pharmacological, neuromodulatory, and behavioral interventions.

Pain Processing in Psychiatric Conditions: A Systematic Review

Pain is a universal, multidimensional experience with sensory, emotional, cognitive, and social components, which is fundamental to our environmental learning when functioning typically. Understanding pain processing in psychiatric conditions could provide unique insight into the underlying pathophysiology or psychiatric disease, especially given the psychobiological overlap with pain processing pathways. Studying pain in psychiatric conditions is likely to provide important insights, yet, there is a limited understanding beyond the work in depression and anxiety. This is a missed opportunity to describe psychiatric conditions in terms of neurobiological alterations. To examine the research into the pain experiences of these groups and the extent to which a-typicality is present, a systematic review was conducted. An electronic search strategy was developed and conducted in several databases. The current systematic review included 46 studies covering five Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5) disorders: autism, attention-deficit hyperactivity disorder (ADHD), schizophrenia, personality disorder, and eating disorders, confirming tentative evidence of altered pain and touch processing. Specifically, hyposensitivity is reported in schizophrenia, personality disorder and eating disorder, hypersensitivity in ADHD, and mixed results for autism. Review of the research highlights a degree of methodological inconsistency in the utilization of comprehensive protocols, the lack of which fails to allow us to understand whether a-typicality is systemic or modality specific.

Which Comes First? An Examination of Associations and Shared Risk Factors for Eating Disorders and Suicidality

PURPOSE OF REVIEW

This narrative review evaluates recent literature on the associations between eating disorders and suicidality and discusses potential shared mechanisms that may account for these relationships. Additionally, the review highlights shortcomings with the literature to date and suggests avenues for future research.

RECENT FINDINGS

Individuals with anorexia nervosa, bulimia nervosa, and binge eating disorder experience elevated rates of suicidality compared to the general population. Suicide risk is higher when eating disorders occur with other psychological conditions. Additionally, genetic factors, emotion dysregulation, trauma, stressful life events, and lack of body regard may have roles in the development of both eating disorders and suicidality. Much of the risk for suicidality in eating disorders appears to be driven by comorbid psychopathology and genetic factors. However, the lack of longitudinal research makes it difficult to draw conclusions about the directionality or temporality of these relations; thus, novel methods are needed.

An interoceptive model of bulimia nervosa: A neurobiological systematic review

The objective of our study was to examine the neurobiological support for an interoceptive sensory processing model of bulimia nervosa (BN). To do so, we conducted a systematic review of interoceptive sensory processing in BN, using the PRISMA guidelines. We searched PsychInfo, Pubmed, and Web of Knowledge databases to identify biological and behavioral studies that examine interoceptive detection in BN. After screening 390 articles for inclusion and conducting a quality assessment of articles that met inclusion criteria, we reviewed 41 articles. We found that global interoceptive sensory processing deficits may be present in BN. Specifically there is evidence of abnormal brain function, structure and connectivity in the interoceptive neural network, in addition to gastric and pain processing disturbances. These results suggest that there may be a neurobiological basis for global interoceptive sensory processing deficits in BN that remain after recovery. Data from taste and heart beat detection studies were inconclusive; some studies suggest interoceptive disturbances in these sensory domains. Discrepancies in findings appear to be due to methodological differences. In conclusion, interoceptive sensory processing deficits may directly contribute to and explain a variety of symptoms present in those with BN. Further examination of interoceptive sensory processing deficits could inform the development of treatments for those with BN.

Dissatisfaction with own body makes patients with eating disorders more sensitive to pain

Body image represents a multidimensional concept including body image evaluation and perception of body appearance. Disturbances of body image perception are considered to be one of the central aspects of anorexia nervosa and bulimia nervosa. There is growing evidence that body image distortion can be associated with changes in pain perception. The aim of our study was to examine the associations between body image perception, body dissatisfaction, and nociception in women with eating disorders and age-matched healthy control women. We measured body dissatisfaction and pain sensitivity in 61 patients with Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition diagnoses of eating disorders (31 anorexia nervosa and 30 bulimia nervosa) and in 30 healthy women. Thermal pain threshold latencies were evaluated using an analgesia meter and body image perception and body dissatisfaction were assessed using Anamorphic Micro software (digital pictures of their own body distorted into larger-body and thinner-body images). Patients with eating disorders overestimated their body size in comparison with healthy controls, but the two groups did not differ in body dissatisfaction. In anorexia and bulimia patient groups, body dissatisfaction (calculated in pixels as desired size/true image size) correlated with pain threshold latencies (r=0.55, p=0.001), while between body image perception (determined as estimation size/true image size) and pain threshold, no correlation was found. Thus, we demonstrated that in patients with eating disorders, pain perception is significantly associated with emotional contrary to sensory (visual) processing of one’s own body image. The more the patients desired to be thin, the more pain-sensitive they were. Our findings based on some shared mechanisms of body dissatisfaction and pain perception support the significance of negative emotions specific for eating disorders and contribute to better understanding of the psychosomatic characteristics of this spectrum of illnesses.

Does the interpersonal-Psychological theory of suicide provide a useful framework for understanding suicide risk among eating disorder patients? A test of the validity of the IPTS

OBJECTIVE

The current study tested whether the Interpersonal-Psychological Theory of Suicide (IPTS) provides a useful framework for understanding elevated suicide rates among individuals with eating disorders (EDs).

METHOD

Based on predictions of the IPTS, we tested whether the combination of thwarted belongingness and perceived burdensomeness was associated with suicidal desire, and whether the combination of thwarted belongingness, perceived burdensomeness, and fearlessness about death was associated with past suicide attempts in an ED sample (n = 100). We also compared these IPTS constructs in an ED sample versus general psychiatric inpatients (n = 85) and college students (i.e., non-clinical comparison group; n = 93).

RESULTS

Within the ED sample, no hypothesized interactions were found, but perceived burdensomeness was associated with suicidal desire, and perceived burdensomeness and fearlessness about death were associated with past suicide attempts. The ED and psychiatric samples had greater thwarted belongingness, perceived burdensomeness, and suicidal desire than the non-clinical comparison group.

DISCUSSION

The IPTS constructs of perceived burdensomeness and fearlessness about death appear to explain some facets of suicidality among people with EDs, but overall, support for the IPTS was limited. Future research on EDs and suicidality should look beyond the IPTS and consider other biological and sociocultural factors for suicide. © 2016 Wiley Periodicals, Inc. (Int J Eat Disord 2016; 49:1082-1086).

Reduced functional connectivity in the thalamo-insular subnetwork in patients with acute anorexia nervosa

The neural underpinnings of anorexia nervosa (AN) are poorly understood. Results from existing functional brain imaging studies using disorder-relevant food- or body-stimuli have been heterogeneous and may be biased due to varying compliance or strategies of the participants. In this study, resting state functional connectivity imaging was used. To explore the distributed nature and complexity of brain function we characterized network patterns in patients with acute AN. Thirty-five unmedicated female acute AN patients and 35 closely matched healthy female participants underwent resting state functional magnetic resonance imaging. We used a network-based statistic (NBS) approach [Zalesky et al., 2010a] to identify differences between groups by isolating a network of interconnected nodes with a deviant connectivity pattern. Group comparison revealed a subnetwork of connections with decreased connectivity including the amygdala, thalamus, fusiform gyrus, putamen and the posterior insula as the central hub in the patient group. Results were not driven by changes in intranodal or global connectivity. No network could be identified where AN patients had increased coupling. Given the known involvement of the identified thalamo-insular subnetwork in interoception, decreased connectivity in AN patients in these nodes might reflect changes in the propagation of sensations that alert the organism to urgent homeostatic imbalances and pain-processes that are known to be severely disturbed in AN and might explain the striking discrepancy between patient's actual and perceived internal body state.

The expression of cytokines and chemokines in the blood of patients with severe weight loss from anorexia nervosa: an exploratory study

Anorexia nervosa (AN) is a serious, potentially life-threatening disorder characterized by severe weight loss, dysregulated eating, and often excessive exercise. While psychiatric illnesses such as depression are associated with increased levels of pro-inflammatory mediators, evidence for such disturbances in patients with AN has been less clear. In an exploratory study of possible disturbances in immune responses in AN, we assayed a panel of cytokines and chemokines in the blood of patients undergoing inpatient treatment, testing the hypothesis that metabolic disturbances in this disease would lead to a pattern of immune disturbances distinct from that of other psychiatric diseases. For this purpose, we evaluated patients by the Beck Depression Inventory-II (BDI-II) and the Eating Disorders Examination-Questionnaire and assessed cytokines and chemokines by enzyme-linked immunosorbent assays. Patients reported a moderate level of depression (mean BDI-II = 22.6) but exhibited few immunologic abnormalities of the kind associated with major depressive disorder [e.g., increased interleukin (IL)-6]; RANTES showed the most frequent elevations and was increased in 4 of the patients studied. Together, these findings suggest that features of AN such as loss of adipose tissue and excessive exercise may attenuate cytokine production and thus modulate the experience of illness that impacts on core features of disease.

Interoceptive sensitivity deficits in women recovered from bulimia nervosa

Self-report studies suggest that patients with bulimia nervosa (BN) evidence difficulties with interoceptive awareness. Indeed, interoceptive deficits may persist after recovery of BN and may be a biological trait that predisposes symptom development in BN. However, no studies to date have directly assessed interoceptive sensitivity, or accuracy in detecting and perceiving internal body cues, in patients with or recovered from BN. Nine women who had recovered from BN and 10 healthy control women completed the Heart Beat Perception Task (HBPT) in which individuals were required to estimate the number of heartbeats between intervals of time. Accuracy scores were compared between groups. Significant differences were found between the groups on the HBPT ((F1,19) = 7.78, p = .013, Cohen's d = 1.16) when controlling for age. These results suggest that deficits in interoceptive sensitivity are present in individuals recovered from BN. Thus interoceptive deficits may be one factor that bridges the gap between brain dysfunction and symptom presentation in BN.

Full body illusion is associated with widespread skin temperature reduction

A central feature of our consciousness is the experience of the self as a unified entity residing in a physical body, termed bodily self-consciousness. This phenomenon includes aspects such as the sense of owning a body (also known as body ownership) and has been suggested to arise from the integration of sensory signals from the body. Several studies have shown that temporally synchronous tactile stimulation of the real body and visual stimulation of a fake or virtual body can induce changes in bodily self-consciousness, typically resulting in a sense of illusory ownership over the fake body. The present study assessed the effect of anatomical congruency of visuo-tactile stimulation on bodily self-consciousness. A virtual body was presented and temporally synchronous visuo-tactile stroking was applied simultaneously to the participants' body and to the virtual body. We manipulated the anatomical locations of the visuo-tactile stroking (i.e., on the back, on the leg), resulting in congruent stroking (stroking was felt and seen on the back or the leg) or incongruent stroking (i.e., stroking was felt on the leg and seen on the back). We measured self-identification with the virtual body and self-location as well as skin temperature. Illusory self-identification with the avatar as well as changes in self-location were experienced in the congruent stroking conditions. Participants showed a decrease in skin temperature across several body locations during congruent stimulation. These data establish that the full-body illusion (FBI) alters bodily self-consciousness and instigates widespread physiological changes in the participant's body.

Insular dysfunction and descending pain inhibition in anorexia nervosa

OBJECTIVE

Reduced perception of pain is a well-established phenomenon in patients with anorexia nervosa (AN). We tested the hypothesis that altered processing of pain within the insula might account for reduced perception of pain.

METHOD

Heat pain thresholds were obtained in nineteen patients with AN and matched controls. Thereafter, a thermode was used to deliver thermal painful stimuli to the right arm during functional magnetic resonance imaging (fMRI) measurements. Stimuli were initiated for 10 s from a baseline resting temperature (32°C) to three different levels (37, 42, 45°C).

RESULTS

Significantly increased heat pain thresholds were observed in patients. A stronger activation during heat pain perception was found in the left posterior insula in controls. In contrast, higher levels of activity were shown in the ipsilateral pons in patients when compared to controls. In patients, we found a significant interrelation between the depression score (Beck depression inventory) and heat pain activations.

CONCLUSION

We suggest that reduced activity in the left posterior insula might contribute to increased pain thresholds in patients, while increased activations in the right anterior insula and pons mirror augmented sympathetic modulation putatively related to amplification of adrenergic descending pain inhibition. In addition, pain thresholds and brain activations were influenced by disease-inherent depressed mood.

Altered insula activation during pain anticipation in individuals recovered from anorexia nervosa: evidence of interoceptive dysregulation

OBJECTIVE

Recent evidence raises the possibility that symptoms of anorexia nervosa (AN) could be related to impaired interoception. Pain is an interoceptive process with well-characterized neuroanatomical pathways that may overlap to a large degree with neural systems that may be dysregulated in individuals with AN, such as the insula.

METHOD

Functional magnetic resonance imaging (fMRI) was used to assess neural substrates of pain anticipation and processing in 10 healthy control women (CW) and 12 individuals recovered from AN (REC AN) in order to avoid the confounding effects of malnutrition. Painful heat stimuli were applied while different colors signaled the intensity of the upcoming stimuli.

RESULTS

REC AN compared with CW showed greater activation within right anterior insula (rAI), dorsolateral prefrontal cortex (dlPFC) and cingulate during pain anticipation, and greater activation within dlPFC and decreased activation within posterior insula during painful stimulation. Greater anticipatory rAI activation correlated positively with alexithymic feelings in REC AN participants.

DISCUSSION

REC AN showed a mismatch between anticipation and objective responses, suggesting altered integration and, possibly, disconnection between reported and actual interoceptive state. Alexithymia assessment provided additional evidence of an altered ability to accurately perceive bodily signals in women recovered from AN.

[The processing of pain in psychiatric diseases]

The perception and processing of pain is disturbed in many psychiatric diseases. Some diseases are known to show decreased perception of pain (e.g. borderline personality disorder), while others are associated with augmented pain perception (e.g. alcohol and drug dependence). The close relationship between psychiatric diseases and pain is most probably caused by aberrant processing of pain in brain structures, known to be involved in psychiatric disorders as well. Aberrant perception and processing of pain in patients with anorexia nervosa (AN) will be used to demonstrate this close relationship. Dysfunction within the insula has been suggested to account for many features of AN and might contribute to reduced pain perception. Moreover, it might lead to increased adrenergic descending inhibition associated with increased sympathetic modulation. Thus, pain research might be able to alter our view on autonomic regulation, which is putatively associated with increased cardiac mortality of the disease.

Intact sensory function in anorexia nervosa

BACKGROUND

In anorexia nervosa (AN), taste and smell are believed to be anhedonic, hunger and pain are muted, and body-image distortion obscures wasting, which together facilitate self-starvation. However, the emphasis on these deficits may be biased because other sensory systems have been sparsely investigated.

OBJECTIVES

Objectives of the study were to clarify whether these dysfunctions are specific or part of a pattern of sensory-perceptual deficits in AN patients and to test the gustatory senses dissociated from ingestion to clarify whether any deficit is sensory or affective.

DESIGN

In 15 adolescent, first-episode, hospitalized, restrictive AN patients and 15 matched healthy controls who responded to gustatory stimuli (intensity and hedonics of 5 basic tastes and tastes and odors of foods and nonfoods), size estimation (manual and oral judgment of size and shape, kinesthesia, and body size and esthetics), cold pain, and auditory and visual processing were compared.

RESULTS

AN patients did not differ on most tests, were better at odor recognition, were less successful in central auditory processing and oral assessment of size and shape, and may have been more sensitive to cold. Body-image dissatisfaction in AN patients was not related to dysfunctional size estimation.

CONCLUSIONS

There is no systematic sensory-perceptual deficit in AN patients, and specifically, not in gustatory function. The few differences shown might be due to fear of food-related stimuli or comorbidity.

Habitual starvation and provocative behaviors: two potential routes to extreme suicidal behavior in anorexia nervosa

Anorexia nervosa (AN) is perhaps the most lethal mental disorder, in part due to starvation-related health problems, but especially because of high suicide rates. One potential reason for high suicide rates in AN may be that those affected face pain and provocation on many fronts, which may in turn reduce their fear of pain and thereby increase risk for death by suicide. The purpose of the following studies was to explore whether repetitive exposure to painful and destructive behaviors such as vomiting, laxative use, and non-suicidal self-injury (NSSI) was a mechanism that linked AN-binge-purging (ANBP) subtype, as opposed to AN-restricting subtype (ANR), to extreme suicidal behavior. Study 1 utilized a sample of 787 individuals diagnosed with one or the other subtype of AN, and structural equation modeling results supported provocative behaviors as a mechanism linking ANBP to suicidal behavior. A second, unexpected mechanism emerged linking ANR to suicidal behavior via restricting. Study 2, which used a sample of 249 AN patients, replicated these findings, including the second mechanism linking ANR to suicide attempts. Two potential routes to suicidal behavior in AN appear to have been identified: one route through repetitive experience with provocative behaviors for ANBP, and a second for exposure to pain through the starvation of restricting in ANR.

Pain sensitivity is reduced in borderline personality disorder, but not in posttraumatic stress disorder and bulimia nervosa

BACKGROUND

Several studies revealed reduced pain sensitivity in patients suffering from borderline personality disorder (BPD) under baseline and stress conditions. To establish whether these findings are specific for BPD, we compared pain thresholds in patients with BPD, posttraumatic stress disorder (PTSD), bulimia nervosa, and healthy controls.

METHODS

The study included 76 female subjects: 16 patients with BPD, 16 patients with PTSD, 20 patients with bulimia nervosa and 24 healthy controls. Heat and cold pain thresholds were assessed under baseline and stress conditions, using a contact thermode. Mental stress was induced by the Paced Auditory Serial Addition Task.

RESULTS

Under baseline conditions, pain thresholds in patients with BPD were significantly higher compared to healthy controls. Patients with PTSD and bulimia nervosa did not show significant differences in pain thresholds compared to healthy controls. Under stress conditions, the difference between BPD patients and healthy controls became even more prominent, whereas the results in the other patient groups remained insignificant.

CONCLUSIONS

Our results support the hypothesis that reduced pain sensitivity is a prominent feature of BPD, which may differentiate this disorder from other stress-related psychiatric conditions.

Use of pain threshold reports to satisfy social needs

OBJECTIVE

To examine the hypothesis that experimental threats to social belongingness, interacting with individual differences in attachment security, cause modification of pain threshold reports by individuals who report high pain thresholds at baseline.

METHODS

In each of three studies, baseline pain threshold and tolerance were assessed in response to a pain task (cold pressor pain in Studies 1 and 2, finger pressure pain in Study 3). Participants then completed a measure of attachment security and were randomly assigned to a social exclusion or control condition (exclusion from a computer game in Study 1, recalling past rejection experiences in Studies 2 and 3). The pain task was administered again to examine the effects on pain threshold and tolerance.

RESULTS

Those with high anxious attachment and high baseline pain thresholds reported higher postmanipulation pain thresholds in the exclusion conditions than in the control conditions. Those with low anxious attachment and high baseline pain thresholds reported lower postmanipulation pain thresholds in the exclusion conditions than in the control conditions. No differences were found for pain tolerance.

CONCLUSIONS

Across studies, results suggested that postmanipulation pain threshold reports of individuals with high baseline pain thresholds were particularly responsive to social exclusion. The form of the response was dependent on the level of anxious attachment. The present studies provide evidence that variance in pain threshold reports not accounted for by pain intensity may reflect the use of pain reports to satisfy social needs. This work also suggests that baseline measures of pain thresholds may, in interaction with psychological variables, have predictive power beyond serving as a control variable.

Psychologically induced cooling of a specific body part caused by the illusory ownership of an artificial counterpart

The sense of body ownership represents a fundamental aspect of our self-awareness, but is disrupted in many neurological, psychiatric, and psychological conditions that are also characterized by disruption of skin temperature regulation, sometimes in a single limb. We hypothesized that skin temperature in a specific limb could be disrupted by psychologically disrupting the sense of ownership of that limb. In six separate experiments, and by using an established protocol to induce the rubber hand illusion, we demonstrate that skin temperature of the real hand decreases when we take ownership of an artificial counterpart. The decrease in skin temperature is limb-specific: it does not occur in the unstimulated hand, nor in the ipsilateral foot. The effect is not evoked by tactile or visual input per se, nor by simultaneous tactile and visual input per se, nor by a shift in attention toward the experimental side or limb. In fact, taking ownership of an artificial hand slows tactile processing of information from the real hand, which is also observed in patients who demonstrate body disownership after stroke. These findings of psychologically induced limb-specific disruption of temperature regulation provide the first evidence that: taking ownership of an artificial body part has consequences for the real body part; that the awareness of our physical self and the physiological regulation of self are closely linked in a top-down manner; and that cognitive processes that disrupt the sense of body ownership may in turn disrupt temperature regulation in numerous states characterized by both.

De-stabilization of the positive vago-vagal reflex in bulimia nervosa

Bulimia nervosa is characterized by consuming large amounts of food over a defined period with a loss of control over the eating. This is followed by a compensatory behavior directed at eliminating the consumed calories, usually vomiting. Current treatments include antidepressants and/or behavioral therapies. Consensus exists that these treatments are not very effective and are associated with high relapse rates. We review evidence from literature and present original data to evaluate the hypothesis that bulimia involves alterations in vago-vagal function. Evidence in support of this include (1) laboratory studies consistently illustrate deficits in meal size, meal termination, and satiety in bulimia; (2) basic science studies indicate that meal size and satiation are under vagal influences; (3) anatomical, behavioral and physiological data suggest that achieving satiety and the initiation of emesis involve common neural substrates; (4) abnormal vagal and vago-vagal reflexive functions extend to non-eating activational stimuli; and (5) studies from our laboratory modulating vagal activation have shown significant effects on binge/vomit frequencies and suggest a return of normal satiation. We propose a model for the pathophysiology of bulimia based upon de-stabilization of a bi-stable positive vago-vagal feedback loop. This model is not meant to be complete, but rather to stimulate anatomical, psychobiological, and translational neuroscience experiments aimed at elucidating the pathophysiology of bulimia and developing novel treatment strategies.

Changes of pain perception, autonomic function, and endocrine parameters during treatment of anorectic adolescents

OBJECTIVES

The underlying mechanisms of reduced pain perception in anorexia nervosa (AN) are unknown. To gain more insight into the pathology, the authors investigated pain perception, autonomic function, and endocrine parameters before and during successful treatment of adolescent AN patients.

METHOD

Heat pain perception was assessed in 15 female adolescent AN patients and matched controls. Results were correlated with autonomic and endocrine parameters (free triiodothyronine, free cortisol). Autonomic function was studied using heart rate variability and pupillary light reflex assessment. To investigate the influence of therapy on these parameters, data were obtained at three different time points.

RESULTS

Heat pain thresholds were significantly increased in the acute state and decreased after weight had been regained for 6 months. Similarly, an increased parasympathetic tone was present in the acute state only. The relative amplitude of the pupillary light reflex showed a positive correlation to pain thresholds over time and predicted disease progression. In addition, the authors found a negative correlation between increased pain thresholds and low free cortisol.

CONCLUSION

Increased pain thresholds are associated with increased parasympathetic tone and a hypothyroid state in AN. This may either indicate common central mechanisms or suggest a causative interaction.

Pain experience related to self-injury in eating disorder patients

A reduced pain sensitivity has been found in eating disorder (ED) patients. These patients often show various types of self-injurious behaviors (SIB) which some experience as painful, while others report analgesia during episodes of SIB. How can we explain these differences? We studied female ED patients (N=185) of whom 84 had admitted some form of SIB in their recent history. The presence/absence of pain report during SIB was not significantly related to the type of ED. The longer the history of SIB, the less pain was reported. Ratings of dissociation and traumatic experiences were higher in patients who did not experience pain while injuring themselves. We discuss several biopsychosocial explanations for these findings with suggestions for future research.

Evidence for a vagal pathophysiology for bulimia nervosa and the accompanying depressive symptoms

BACKGROUND

The bilateral vagus nerves (Cranial X) provide both afferent and efferent connections between the viscera and the caudal medulla. The afferent branches increasingly are being recognized as providing significant input to the central nervous system for modulation of complex behaviors. In this paper, we review evidence from our laboratory that increases in vagal afferent activity are involved in perpetuating binge-eating and vomiting in bulimia nervosa. Preliminary findings are also presented which suggest that a subgroup of depressions may have a similar pathophysiology.

METHODS

Two main approaches were used to study the role of vagal afferents. Ondansetron (ONDAN), a 5-HT3 antagonist, was used as a pharmacological tool for inhibiting or reducing vagal afferent neurotransmission. Second, somatic pain detection thresholds were assessed for monitoring a physiological process known to be modulated by vagal afferents, including the gastric branches involved in meal termination and satiety. High levels of vagal activity result in an increase in pain detection thresholds. Depressive symptoms were assessed using the Beck Depression Inventory (BDI). Positron Emission Tomography (PET) was used to identify higher cortical brain areas activated by vagal stimulation produced by proximal gastric distention in normal eating subjects.

RESULTS

Double-blind treatment of severe bulimia nervosa subjects with ONDAN resulted in a rapid and significant decrease in binge-eating and vomiting compared to placebo controls. The decrease in abnormal eating episodes was accompanied by a return of normal satiety. Pain detection thresholds measured weekly over the course of the treatment protocol were found to dynamically fluctuate in association with bulimic episodes. Thresholds were the most elevated during periods of short-term abstinence from the behaviors, suggesting that not engaging in a binge/vomit episode is accompanied by an increase in vagal activity. ONDAN also resulted in abolition of the fluctuations in pain thresholds. Depressive symptoms in these subjects also were reduced by ONDAN. Like pain thresholds, depressive symptoms varied dynamically with the bulimic behaviors, with BDI scores increasing (more depressed) as more time elapsed since the last bulimic episode. PET studies indicated that mechanical distention of the stomach with a balloon (a non-nutritive stimulus) was associated with the activation of several brain loci, including those associated with vagal activation (parabrachial nucleus), emotive aspects of eating (lateral inferior frontal and orbitofrontal), and depressive symptoms (anterior cingulate).

CONCLUSIONS

The results of the ONDAN study in bulimia nervosa subjects suggest that cyclic increases in vagal activity drive the urge to binge-eat and vomit. The alterations in vagal firing patterns are possibly a physiological adaptation to the high levels of vagal stimulation initially provided by voluntarily binge-eating and vomiting for weight control. The depressive symptoms that occur in association with the urge to binge-eat are also likely due to the cyclic increase in vagal activity. This suggestion is supported by the reduction of depressive symptoms during ONDAN treatment in bulimia subjects and PET imaging studies in normal eating subjects showing that brain loci classically involved in depression are activated by vagal stimulation administered by mechanical gastric distention. In normal eating individuals, depressions accompanying visceral diseases may also be vagally mediated. Ondansetron and other drugs known to modulate vagal activity may be helpful in treating depressions of this origin.

Gastric compliance in bulimia nervosa

Bulimia nervosa (BN) is a psychiatric illness characterized by eating binges followed by inappropriate behavioral attempts to compensate for the binges, usually vomiting or laxative abuse. Patients with BN have disturbances in the development of satiety during a meal as well as disturbances in functions of the upper gastrointestinal tract such as slowed gastric emptying, impaired gastric accommodation reflex and blunted cholecystokinin release. The present study examined gastric compliance and sensory responses to gastric distention in women with BN and controls. Sixteen women with BN and 13 healthy control subjects swallowed an inflatable bag that was placed in the proximal stomach. The bag was inflated to produce increasing steps of pressure against the stomach wall, before and after consumption of a 200 ml (200 Kcal) liquid meal. Pressure and volume were recorded for 2-min periods, beginning at 0 mm Hg pressure and increasing in steps of 2 mm Hg until subjects reported discomfort, gastric volume reached 600 ml, or pressure reached 20 mm Hg. At each pressure step subjects made sensory ratings. Gastric compliance was calculated as the slope of the best-fit straight line of each subject's gastric volume vs. gastric pressure. There was a significant postmeal increase in gastric compliance in both groups of subjects but there was no difference in compliance between patients with BN and controls. Patients with BN appeared to have diminished sensitivity to gastric distention. In conclusion, although other studies have described gastrointestinal abnormalities associated with BN, the current study found gastric compliance of patients with BN to be normal.

Double stimulation of tiny skin areas in human subjects increases the number of C- and Aδ-fiber responses

The stimulation of tiny skin areas has been shown to be a useful method for the investigation of the central nervous processing of C-fiber stimulation. However, recent studies have also indicated that most subjects fail to recognize a large number of such stimulation. This fact renders this method to be rather time consuming, a fact that limits its applicability. To reduce the duration of examination, we here examined the effects of double stimulation of tiny skin areas as compared to the stimulation of tiny skin areas with a single stimulus. The comparison is based on subjects' number of recognized stimuli for single and double stimulation and ratings of stimulus intensity. Double stimulation of tiny skin areas resulted in a significant increase of the number of recognized stimuli as compared to single stimulation. This increase of the number of recognized stimuli is accompanied by an increase of the averaged subjects' experience of stimulus intensity. However, there was no significant increase of intensity rating for the different types of fibers stimulated. Data indicate that the double stimulation of tiny skin areas represents an alternative option to the application of single stimuli to tiny skin areas that significantly reduces the exposure time of subjects in order to evaluate behavioral consequences of the stimulation as well as central nervous processing of C- and Adelta-fiber input.

Elevated pain threshold in eating disorders: physiological and psychological factors

Several studies have found decreased pain sensitivity in patients with eating disorders but it is unclear what physiological and psychological factors are associated with this abnormality. In the present investigation, thermal pain threshold latency, somatoform dissociation, body image disturbance and physiological indices of autonomic neural system activity were measured in 39 female patients with eating disorders (21 with anorexia nervosa and 18 with bulimia nervosa) and 17 healthy women. Pain threshold was elevated in patients with eating disorders, especially those with binge-purging symptomatology. A regression analysis indicated that increased pain threshold is moderately associated with decreased peripheral skin temperature and weakly associated with lack of familiarity with one's own body. However, the between group differences in pain perception remained significant after controlling for peripheral skin temperature. Hence, elevation of pain threshold in eating disorders is a replicable finding, which is not explicable by peripheral indices of autonomic system activity or by somatoform dissociation. In future research it may be evaluated as a potential marker of broader phenotype of decreased interoceptive awareness, which may be associated with vulnerability to the development of eating disorders.

Psychobiology of altered states of consciousness

The article reviews the current knowledge regarding altered states of consciousness (ASC) (a) occurring spontaneously, (b) evoked by physical and physiological stimulation, (c) induced by psychological means, and (d) caused by diseases. The emphasis is laid on psychological and neurobiological approaches. The phenomenological analysis of the multiple ASC resulted in 4 dimensions by which they can be characterized: activation, awareness span, self-awareness, and sensory dynamics. The neurophysiological approach revealed that the different states of consciousness are mainly brought about by a compromised brain structure, transient changes in brain dynamics (disconnectivity), and neurochemical and metabolic processes. Besides these severe alterations, environmental stimuli, mental practices, and techniques of self-control can also temporarily alter brain functioning and conscious experience.

Pain perception in recovered bulimia nervosa patients

OBJECTIVE

Decreased pain sensitivity is found in individuals who are ill with bulimia nervosa (BN). The purpose of this study is to determine whether altered pain perception persists after recovery from bulimia nervosa (RBN).

METHODS

Eleven women who were recovered from BN for more than 1 year were compared with 15 healthy volunteer women. The participants received two pain evaluations--thermal pain stimulation (TPS), which evaluates threshold and tolerance to heat, and the submaximal effort tourniquet test (SETT), which assesses threshold and tolerance to ischemic pain induced by inflation of a blood pressure cuff.

RESULTS

Compared with the controls, the RBN women showed elevated pain threshold as measured with the SETT and a tendency to elevated pain threshold on the TPS.

DISCUSSION

Decreased pain sensitivity persists after recovery from BN and may reflect altered modulatory function in this illness.

Anaesthetic implications of anorexia nervosa

The provision of anaesthesia for patients suffering from anorexia nervosa or bulimia nervosa is not without its risks. The anaesthetist needs to appreciate that these eating disorders can predispose the patient to significant risk of multi-organ dysfunction related to starvation and purging. Any such organ dysfunction can have serious implications on morbidity and mortality. Therefore, careful peri-operative management is essential to avoid anaesthetic complications. Both disorders are common, with incidences in the general population of up to 30% in girls and young women. A review of the literature on the provision of anaesthesia for anorexic patients was carried out to evaluate the potential impact of these disorders on the patient's physiology and the subsequent implications for anaesthesia.

Deficits in haptic perception and right parietal theta power changes in patients with anorexia nervosa before and after weight gain

OBJECTIVE

Our goal was to investigate whether patients with anorexia nervosa (AN) show deficits in haptic exploration tasks before and after weight gain.

METHOD

The haptic exploration tasks consisted of palpating the structure of six sunken reliefs in sequence with both hands, eyes closed. After each exploration, the structure was reproduced on a piece of paper. A 19-channel digital electroencephalogram (EEG; linked ears) was continuously recorded during rest and haptic tasks for 10 AN patients (females, mean age: 15.90) and 10 healthy controls (CO; females, mean age: 16.14). Mean spectral power density was calculated as the mean amplitude of the spectral lines of the theta band (4-8 Hz). The AN patients were examined again after weight gain (T(0) and T(1)).

RESULTS

The reproductions submitted by the AN patients were of notably poorer quality than those of the CO. Reproduction quality was unchanged after weight gain and independent of body mass index and intelligence. Mean exploration time was similiar in AN patients and CO. The analysis of spectral EEG power of both groups showed significant decrease in power data in the theta frequency band during haptic exploration compared with the rest intervals. The comparison of the theta power between CO and AN patients during haptic exploration showed major differences between the groups in both T(0) and T(1). Theta power was lower in AN patients than in the CO over the right hemisphere and right parietal regions.

DISCUSSION

The quality of reproduction of the haptic stimuli and the theta-power changes indicate a cortical dysfunction and deficits in somatosensory integration processing of the right parietal cortex in AN patients even after weight gain.

Psychological determinants of fibromyalgia and related syndromes

Fibromyalgia and other chronic pain and fatigue syndromes constitute an increasingly greater societal burden that currently is not being approached effectively by traditional Western medicine. Although the hallmarks of fibromyalgia--chronic widespread pain, fatigue, and multiple other somatic symptoms--have neurophysiologic and endocrinologic underpinnings, these biological aspects derive primarily from psychological variables. Female gender, adverse experiences during childhood, psychological vulnerability to stress, and a stressful, often frightening environment and culture are important antecedents of fibromyalgia. To understand fibromyalgia and related syndromes and to provide optimum care requires a biopsychosocial, not a biomedical, viewpoint.

Pain modulation role of melatonin in eating disorders

The objective of this study was to test the effect of melatonin on thermal pain threshold in female patients with eating disorders. Fourteen patients were included in the study. We found a parabolic relation between pain threshold and the content of urine sulfatoxymelatonin (r = 0.6299, P < 0.05). We can speculate that increase in severity of eating disorder pathology may decrease both the melatonin level and pain sensitivity. In contrast with expected melatonin analgesic effect, our results showed its possible normalizing influence as well on pathologically decreased pain sensitivity.

Effect of decreasing afferent vagal activity with ondansetron on symptoms of bulimia nervosa: a randomised, double-blind trial

BACKGROUND

Several lines of evidence have led us to postulate that afferent vagal hyperactivity could be an important factor in the pathophysiology of the eating disorder bulimia nervosa. Ondansetron is a peripherally active antagonist of the serotonin receptor 5-HT3, and is marketed for prevention of vagally-mediated emesis caused by cancer chemotherapeutic agents. We investigated the effects of ondansetron on bulimic behaviours in patients with severe and chronic bulimia nervosa in a randomised, double-blind, placebo-controlled study.

METHODS

We enrolled patients with severe bulimia nervosa (at least seven coupled binge/vomit episodes per week). The patients were otherwise healthy, their weight was normal, and they were not receiving medical or psychiatric treatment. During the first week of the study, patients recorded all eating-behaviour events to establish a baseline. In the second week, all patients received placebo, but were told that they were receiving either placebo or active drug. At the end of this single-blind phase, patients were randomly assigned placebo or ondansetron (24 mg daily) for a further 4 weeks. The primary outcome measure was the number of binge/vomit episodes per week. Data were analysed by intention to treat.

FINDINGS

29 patients met the inclusion criteria, of whom 28 completed the baseline study, and 26 completed the single-blind placebo week. 12 patients were assigned placebo, and 14 ondansetron; one patient in the ondansetron group dropped out owing to accidental injury. During the 4th week of double-blind treatment, mean binge/vomit frequencies were 13.2 per week (SD 11.6) in the placebo group, versus 6.5 per week (3.9) in the ondansetron group (estimated difference 6.8 [95% CI 4.0-9.5]; p<0.0001). The ondansetron group also showed significant improvement, compared with the placebo group, in two secondary indicators of disease severity. The amount of time spent engaging in bulimic behaviours was decreased on average by 7.6 h per week in the ondansetron group, compared with 2.3 h in the placebo group (estimated difference 5.1 [0.6-9.7]). Similarly, the number of normal meals and snacks increased on average by 4.3 normal eating episodes without vomiting per week in the ondansetron group, compared with 0.2 in the placebo group (estimated difference 4.1 [1.0-7.2]).

INTERPRETATION

The decrease in binge-eating and vomiting under ondansetron treatment was not achieved by compensatory changes in eating behaviour such as by a smaller number of binges of longer duration, or by not eating, or by binge-eating without vomiting. Instead, our findings indicate a normalisation of the physiological mechanism(s) controlling meal termination and satiation. Since meal termination and satiety are mainly vagally mediated functions, since binge-eating and vomiting produce intense stimulation of vagal afferent fibres, and since ondansetron and other 5-HT3 antagonists decrease afferent vagal activity, the symptom improvement may result from a pharmacological correction of abnormal vagal neurotransmission.