New insights into symptoms and neurocircuit function of anorexia nervosa

Psychosomatic syndromes and anorexia nervosa

BACKGROUND

In spite of the role of some psychosomatic factors as alexithymia, mood intolerance, and somatization in both pathogenesis and maintenance of anorexia nervosa (AN), few studies have investigated the prevalence of psychosomatic syndromes in AN. The aim of this study was to use the Diagnostic Criteria for Psychosomatic Research (DCPR) to assess psychosomatic syndromes in AN and to evaluate if psychosomatic syndromes could identify subgroups of AN patients.

METHODS

108 AN inpatients (76 AN restricting subtype, AN-R, and 32 AN binge-purging subtype, AN-BP) were consecutively recruited and psychosomatic syndromes were diagnosed with the Structured Interview for DCPR. Participants were asked to complete psychometric tests: Body Shape Questionnaire, Beck Depression Inventory, Eating Disorder Inventory-2, and Temperament and Character Inventory. Data were submitted to cluster analysis.

RESULTS

Illness denial (63%) and alexithymia (54.6%) resulted to be the most common syndromes in our sample. Cluster analysis identified three groups: moderate psychosomatic group (49%), somatization group (26%), and severe psychosomatic group (25%). The first group was mainly represented by AN-R patients reporting often only illness denial and alexithymia as DCPR syndromes. The second group showed more severe eating and depressive symptomatology and frequently DCPR syndromes of the somatization cluster. Thanatophobia DCPR syndrome was also represented in this group. The third group reported longer duration of illness and DCPR syndromes were highly represented; in particular, all patients were found to show the alexithymia DCPR syndrome.

CONCLUSIONS

These results highlight the need of a deep assessment of psychosomatic syndromes in AN. Psychosomatic syndromes correlated differently with both severity of eating symptomatology and duration of illness: therefore, DCPR could be effective to achieve tailored treatments.

The role of "mixed" orexigenic and anorexigenic signals and autoantibodies reacting with appetite-regulating neuropeptides and peptides of the adipose tissue-gut-brain axis: relevance to food intake and nutritional status in patients with anorexia nervosa and bulimia nervosa

Eating disorders such as anorexia (AN) and bulimia nervosa (BN) are characterized by abnormal eating behavior. The essential aspect of AN is that the individual refuses to maintain a minimal normal body weight. The main features of BN are binge eating and inappropriate compensatory methods to prevent weight gain. The gut-brain-adipose tissue (AT) peptides and neutralizing autoantibodies play an important role in the regulation of eating behavior and growth hormone release. The mechanisms for controlling food intake involve an interplay between gut, brain, and AT. Parasympathetic, sympathetic, and serotoninergic systems are required for communication between brain satiety centre, gut, and AT. These neuronal circuits include neuropeptides ghrelin, neuropeptide Y (NPY), peptide YY (PYY), cholecystokinin (CCK), leptin, putative anorexigen obestatin, monoamines dopamine, norepinephrine (NE), serotonin, and neutralizing autoantibodies. This extensive and detailed report reviews data that demonstrate that hunger-satiety signals play an important role in the pathogenesis of eating disorders. Neuroendocrine dysregulations of the AT-gut-brain axis peptides and neutralizing autoantibodies may result in AN and BN. The circulating autoantibodies can be purified and used as pharmacological tools in AN and BN. Further research is required to investigate the orexigenic/anorexigenic synthetic analogs and monoclonal antibodies for potential treatment of eating disorders in clinical practice.

Ghrelin: central and peripheral implications in anorexia nervosa

Increasing clinical and therapeutic interest in the neurobiology of eating disorders reflects their dramatic impact on health. Chronic food restriction resulting in severe weight loss is a major symptom described in restrictive anorexia nervosa (AN) patients, and they also suffer from metabolic disturbances, infertility, osteopenia, and osteoporosis. Restrictive AN, mostly observed in young women, is the third largest cause of chronic illness in teenagers of industrialized countries. From a neurobiological perspective, AN-linked behaviors can be considered an adaptation that permits the endurance of reduced energy supply, involving central and/or peripheral reprograming. The severe weight loss observed in AN patients is accompanied by significant changes in hormones involved in energy balance, feeding behavior, and bone formation, all of which can be replicated in animals models. Increasing evidence suggests that AN could be an addictive behavior disorder, potentially linking defects in the reward mechanism with suppressed food intake, heightened physical activity, and mood disorder. Surprisingly, the plasma levels of ghrelin, an orexigenic hormone that drives food-motivated behavior, are increased. This increase in plasma ghrelin levels seems paradoxical in light of the restrained eating adopted by AN patients, and may rather result from an adaptation to the disease. The aim of this review is to describe the role played by ghrelin in AN focusing on its central vs. peripheral actions. In AN patients and in rodent AN models, chronic food restriction induces profound alterations in the « ghrelin » signaling that leads to the development of inappropriate behaviors like hyperactivity or addiction to food starvation and therefore a greater depletion in energy reserves. The question of a transient insensitivity to ghrelin and/or a potential metabolic reprograming is discussed in regard of new clinical treatments currently investigated.

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.

Recovery from anorexia nervosa includes neural compensation for negative body image

OBJECTIVE

To examine whether frontal lobe mediated regulation of emotion permits women to recover from anorexia nervosa (AN).

METHOD

Brain activity associated with the disruption of working memory by images of bodies was examined in women who had recovered from AN and in control women.

RESULTS

Negatively rated images were more disruptive to working memory than neutral or positively rated images in both groups; however, amygdala and fusiform activation were greater in women who had recovered from AN than in controls when viewing images of bodies during the working memory task. There were no group differences in lateral prefrontal activity. However, there was more suppression of medial prefrontal cortex activity in women who had recovered from AN in comparison to controls when negatively rated images were presented during the working memory task.

DISCUSSION

These results suggest that recovery from AN is not achieved by dampening an amygdala mediated emotional response to bodies, but instead by developing compensatory neural mechanisms that prevent emotional responses from disturbing cognition.

Disruption of visuospatial and somatosensory functional connectivity in anorexia nervosa

BACKGROUND

Although body image disturbance is considered one of the core characteristics of anorexia nervosa (AN), the exact nature of this complex feature is poorly understood. Task-related functional magnetic resonance imaging studies can only partially explore the multimodal complexity of body consciousness, which is a complex cognition underpinned by aspects of visual perception, proprioception, and touch. The aim of the present study was to explore the functional connectivity of networks involved in visuospatial and somatosensory processing in AN.

METHODS

Twenty-nine subjects with AN, 16 women who had recovered from it, and 26 healthy women underwent a resting-state functional magnetic resonance imaging scan and neuropsychological assessment of their visuospatial abilities using the Rey-Osterrieth Complex Figure Test.

RESULTS

Both AN groups showed areas of decreased connectivity in the ventral visual network, a network involved in the "what?" pathway of visual perception. Even more interestingly, the AN group, but not the recovered AN group, displayed increased coactivation in the left parietal cortex, encompassing the somatosensory cortex, in an area implicated in long-term multimodal spatial memory and representation, even in the absence of visual information. A neuropsychological assessment of visuospatial abilities revealed that aspects of detail processing and global integration (central coherence) showed correlations with connectivity of this brain area in the AN group.

CONCLUSIONS

Our findings show that AN is associated with double disruption of brain connectivity, which shows a specific association with visuospatial difficulties and may explain the failure of the integration process between visual and somatosensory perceptual information that might sustain body image disturbance.

Increased resting state functional connectivity in the default mode network in recovered anorexia nervosa

Functional brain imaging studies have shown abnormal neural activity in individuals recovered from anorexia nervosa (AN) during both cognitive and emotional task paradigms. It has been suggested that this abnormal activity which persists into recovery might underpin the neurobiology of the disorder and constitute a neural biomarker for AN. However, no study to date has assessed functional changes in neural networks in the absence of task-induced activity in those recovered from AN. Therefore, the aim of this study was to investigate whole brain resting state functional connectivity in nonmedicated women recovered from anorexia nervosa. Functional magnetic resonance imaging scans were obtained from 16 nonmedicated participants recovered from anorexia nervosa and 15 healthy control participants. Independent component analysis revealed functionally relevant resting state networks. Dual regression analysis revealed increased temporal correlation (coherence) in the default mode network (DMN) which is thought to be involved in self-referential processing. Specifically, compared to healthy control participants the recovered anorexia nervosa participants showed increased temporal coherence between the DMN and the precuneus and the dorsolateral prefrontal cortex/inferior frontal gyrus. The findings support the view that dysfunction in resting state functional connectivity in regions involved in self-referential processing and cognitive control might be a vulnerability marker for the development of anorexia nervosa.

What can cognitive neuroscience teach us about anorexia nervosa?

Anorexia nervosa (AN) is a complex illness and highly challenging to treat. One promising approach to significantly advance our understanding of the underlying pathophysiology of AN involves developing a cognitive neuroscience model of illness. Cognitive neuroscience uses probes such as neuropsychological tasks and neuroimaging techniques to identify the neural underpinnings of behavior. With this approach, advances have been made in identifying higher-order cognitive processes that likely mediate symptom expression in AN. Identification of related neuropathology is beginning. Such findings led to the development of complex neurobehavioral models that aim to explain the etiology and persistence of AN. Future research will use these advanced tools to test and refine hypotheses about the underlying mechanisms of AN.

Anorexia nervosa and obesity are associated with opposite brain reward response

Anorexia nervosa (AN) is a severe psychiatric disorder associated with food avoidance and malnutrition. In this study, we wanted to test whether we would find brain reward alterations in AN, compared with individuals with normal or increased body weight. We studied 21 underweight, restricting-type AN (age M 22.5, SD 5.8 years), 19 obese (age M 27.1, SD 6.7 years), and 23 healthy control women (age M 24.8, SD 5.6 years), using blood oxygen level-dependent functional magnetic resonance brain imaging together with a reward-conditioning task. This paradigm involves learning the association between conditioned visual stimuli and unconditioned taste stimuli, as well as the unexpected violation of those learned associations. The task has been associated with activation of brain dopamine reward circuits, and it allows the comparison of actual brain response with expected brain activation based on established neuronal models. A group-by-task condition analysis (family-wise-error-corrected P<0.05) indicated that the orbitofrontal cortex differentiated all three groups. The dopamine model reward-learning signal distinguished groups in the anteroventral striatum, insula, and prefrontal cortex (P<0.001, 25 voxel cluster threshold), with brain responses that were greater in the AN group, but lesser in the obese group, compared with controls. These results suggest that brain reward circuits are more responsive to food stimuli in AN, but less responsive in obese women. The mechanism for this association is uncertain, but these brain reward response patterns could be biomarkers for the respective weight state.

Clinical and temperamental correlates of body image disturbance in eating disorders

OBJECTIVE

Although body image disturbance (BID) is considered a core symptom in anorexia nervosa (AN) and bulimia nervosa (BN), little is known about its psychopathological correlates. The present study aimed at analysing the correlation of aspects of BID with psychopathological and temperamental characteristics.

METHOD

A sample of 1288 patients (538 AN and 750 BN) were assessed through a structured diagnostic interview, the Eating Disorders Inventory and Tridimensional Personality Questionnaire. Cognition of body image distortion, weight checking, fear of weight gain and body dissatisfaction were assessed by specific questions during the interview.

RESULTS

Various aspects of BID formed similar, but not identical, dimensions in AN and BN. In both groups, anticipatory anxiety and interoceptive awareness were significantly and independently associated with body image distortion, whereas ineffectiveness was associated with weight checking.

DISCUSSION

Body image disturbance is a multidimensional characteristic linked to psychological features, such as anticipatory anxiety, ineffectiveness and interoceptive awareness. These findings have scientific and treatment implications, and should be considered by clinicians in adopting successful treatment strategies.

A debate on current eating disorder diagnoses in light of neurobiological findings: is it time for a spectrum model?

BACKGROUND

Sixty percent of eating disorders do not meet criteria for anorexia- or bulimia nervosa, as defined by the Diagnostic and Statistical Manual version 4 (DSM-IV). Instead they are diagnosed as 'eating disorders not otherwise specified' (EDNOS). Discrepancies between criteria and clinical reality currently hampering eating disorder diagnoses in the DSM-IV will be addressed by the forthcoming DSM-V. However, future diagnoses for eating disorders will rely on current advances in the fields of neuroimaging and genetics for classification of symptoms that will ultimately improve treatment.

DISCUSSION

Here we debate the classification issues, and discuss how brain imaging and genetic discoveries might be interwoven into a model of eating disorders to provide better classification and treatment. The debate concerns: a) current issues in the classification of eating disorders in the DSM-IV, b) changes proposed for DSM-V, c) neuroimaging eating disorder research and d) genetic eating disorder research.

SUMMARY

We outline a novel evidence-based 'impulse control' spectrum model of eating disorders. A model of eating disorders is proposed that will aid future diagnosis of symptoms, coinciding with contemporary suggestions by clinicians and the proposed changes due to be published in the DSM-V.

Dysregulation of brain reward systems in eating disorders: neurochemical information from animal models of binge eating, bulimia nervosa, and anorexia nervosa

Food intake is mediated, in part, through brain pathways for motivation and reinforcement. Dysregulation of these pathways may underlay some of the behaviors exhibited by patients with eating disorders. Research using animal models of eating disorders has greatly contributed to the detailed study of potential brain mechanisms that many underlie the causes or consequences of aberrant eating behaviors. This review focuses on neurochemical evidence of reward-related brain dysfunctions obtained through animal models of binge eating, bulimia nervosa, or anorexia nervosa. The findings suggest that alterations in dopamine (DA), acetylcholine (ACh) and opioid systems in reward-related brain areas occur in response to binge eating of palatable foods. Moreover, animal models of bulimia nervosa suggest that while bingeing on palatable food releases DA, purging attenuates the release of ACh that might otherwise signal satiety. Animal models of anorexia nervosa suggest that restricted access to food enhances the reinforcing effects of DA when the animal does eat. The activity-based anorexia model suggests alterations in mesolimbic DA and serotonin occur as a result of restricted eating coupled with excessive wheel running. These findings with animal models complement data obtained through neuroimaging and pharmacotherapy studies of clinical populations. Information on the neurochemical consequences of the behaviors associated with these eating disorders will be useful in understanding these complex disorders and may inform future therapeutic approaches, as discussed here. This article is part of a Special Issue entitled 'Central Control of Food Intake'.

Increased capacity to delay reward in anorexia nervosa

Individuals with anorexia nervosa (AN) are often characterized as possessing excessive self-control and are unusual in their ability to reduce or avoid the consumption of palatable foods. This behavior promotes potentially life-threatening weight loss and suggests disturbances in reward processing. We studied whether individuals with AN showed evidence of increased self-control by examining the tendency to delay receipt of a monetary, non-food related, reward. Underweight AN (n = 36) and healthy controls (HC, n = 28) completed a monetary intertemporal choice task measuring delay discounting factor. Individuals with AN reduced the value of a monetary reward over time significantly less than HC (F[1,61] = 5.03; p = 0.029). Secondary analyses indicated that the restricting subtype of AN, in particular, showed significantly less discounting than HC (F[1,46] = 8.3; p = 0.006). These findings indicate that some individuals with AN show less temporal discounting than HC, suggestive of enhanced self-control that is not limited to food consumption. This is in contrast to other psychiatric disorders, for example, substance abuse, which are characterized by greater discounting. Though preliminary, these findings suggest that excessive self-control may contribute to pathological processes and individuals with AN may have neuropsychological characteristics that enhance their ability to delay reward and thereby may help to maintain persistent food restriction.

Association between serotonin transporter gene polymorphism and eating disorders outcome: a 6-year follow-up study

Eating disorder patients show different long-term outcomes, and trait-related alterations of serotonergic function, which might be related with the serotonin transporter (5-HTT) gene. We studied the relationships between 5-HTTLPR polymorphism, eating specific and general psychopathology and the long-term outcome of anorexia nervosa (AN) and bulimia nervosa (BN) patients. We evaluated the distribution of the functional 5-HTTLPR polymorphism in a series of 201 Italian, Caucasian, eating disorder patients (113 with AN and 88 with BN binge/purging (BP subtype) and in 150 Caucasian unrelated controls. Prior to starting an individual cognitive behavior therapy, a clinical assessment was performed by means of the structured clinical interview for DSM-IV axis I disorders and several self-report questionnaires. This assessment was repeated at the end of treatment, 3 years after the end of treatment and 3 years after the first follow-up. Diagnostic changes between AN and BN were frequent (28.3%), and the presence of depressive disorders was associated with a higher rate of diagnostic crossover during the follow-up period. The S-allele of the 5-HTTLPR genotype increases the risk susceptibility for both depressive comorbidity (OR = 4.23; 95% CI, 1.45-12.37) and diagnostic crossover during the follow-up period in AN patients (OR = 5.04; 95% CI, 1.69-14.98). Logistic regression analyses confirmed these findings, when the interaction between genotype and psychiatric comorbidity as predictors of diagnostic instability in AN patients were taken into account. No significant association was found between 5-HTTLPR genotype and recovery. The S-allele of the 5-HTTLPR genotype increases the risk for depressive disorders comorbidity, and moderates the long-term outcome of anorectic patients.

Deep-brain stimulation for anorexia nervosa

OBJECTIVE

Anorexia nervosa (AN) is a complex and severe, sometimes life-threatening, psychiatric disorder with high relapse rates under standard treatment. After decades of brain-lesioning procedures offered as a last resort, deep-brain stimulation (DBS) has come under investigation in the last few years as a treatment option for severe and refractory AN.

METHODS AND RESULTS

In this jointly written article, Sun et al. (the Shanghai group) report an average of 65% increase in body weight in four severe and refractory patients with AN after they underwent the DBS procedure (average follow-up: 38 months). All patients weighed greater than 85% of expected body weight and thus no longer met the diagnostic criteria of AN at last follow-up. Nuttin et al. (the Leuven group) describe other clinical studies that provide evidence for the use of DBS for AN and further discuss patient selection criteria, target selection, and adverse event of this evolving therapy.

CONCLUSION

Preliminary results from the Shanghai group and other clinical centers showed that the use of DBS to treat AN may be a valuable option for weight restoration in otherwise-refractory and life-threatening cases. The nature of this procedure, however, remains investigational and should not be viewed as a standard clinical treatment option. Further scientific investigation is essential to warrant the long-term efficacy and safety of DBS for AN.

Functional and effective connectivity of anterior insula in anorexia nervosa and bulimia nervosa

The anterior insula has been proposed to play a crucial role in eating disorders. However, it is still poorly understood how the anterior insula is involved in anorexia nervosa (AN) and bulimia nervosa (BN), which are characterized by opposite motivational responses to food. We applied a cue-reactivity paradigm using blood oxygen level-dependent functional magnetic resonance imaging in women with AN (N=18) and BN (N=20) and age-matched healthy controls (N=20). We defined the left anterior insula as a region-of-interest and performed seed-based functional connectivity and effective connectivity MRI analysis. In response to food images compared to non-food images, both the AN group and BN group demonstrated increased activity in the left anterior insula. In the AN group, the left anterior insula demonstrated significant interactions with the right insula and right inferior frontal gyrus. In the BN group, the left anterior insula demonstrated significant interactions with the medial orbitofrontal cortex. The distinct patterns of functional and effective connectivity of the anterior insula may contribute to the different clinical features of AN and BN.

Neural basis of a multidimensional model of body image distortion in anorexia nervosa

Body image distortion is a key symptom of anorexia nervosa (AN). The majority of the neuroimaging studies on body image distortion in AN conceptualized it as an unidimensional symptom. However, behavioural research considers such symptom as a multidimensional construct. Our paper systematically reviews the functional magnetic resonance (fMRI) studies on body image distortion in AN and classifies them according to a speculative model of body image distortion, that consists of the three most widely accepted components in the behavioural research: perceptive, affective and cognitive. We found that: (1) the perceptive component is mainly related to alterations of the precuneus and the inferior parietal lobe; (2) the affective component is mainly related to alterations of the prefrontal cortex, the insula and the amygdala; (3) the cognitive component has been weakly explored. These evidences seem to confirm that specific neural alterations are related to the components of the body image distortion in AN. Further neuroimaging studies are needed to better understand the complexity of the body image distortion in AN.

Advances in the diagnosis of anorexia nervosa and bulimia nervosa using brain imaging

INTRODUCTION: Anorexia and bulimia nervosa are severe psychiatric disorders and the availability of brain imaging techniques hold promise that those techniques will be useful in clinical practice. AREAS COVERED: In this review I describe currently available brain imaging techniques and focus on the brain imaging methods functional magnetic resonance imaging (fMRI) and positron emission tomography (PET). Those techniques have helped describe alterations in brain circuitry in AN and BN that related to anxiety and reward processing. Novel computational models help further define brain function in relation to particular neurotransmitters. EXPERT OPINION: Brain imaging techniques are exciting methods to learn about brain function and progress has been made to identify in healthy populations brain circuits that code behaviors. These techniques have been used in AN and BN over the past decade and have improved our understanding of brain function in those disorders. Still, human brain imaging is not at a point yet where it could be used diagnostically. However, with the refinement of imaging hardware as well as improved models that describe brain function we will get closer to our aims to not only better understand the neurobiology of those disorders, but predict illness development, treatment response and long term prognosis.

Allocentric lock in anorexia nervosa: new evidences from neuroimaging studies

Individuals with anorexia nervosa (AN) have a disturbance in the way in which their body is experienced and tend to evaluate negatively their own body and body parts. It is controversial whether these symptoms are secondary to dysfunctions in the neuronal processes related to appetite and emotional regulation or reflect a primary disturbance in the way the body is experienced and remembered. According to the "Allocentric Lock Hypothesis--ALH" (http://dx.doi.org/10.1016/j.mehy.2011.10.039) individuals with AN may be locked to an allocentric (observer view) negative memory of the body that is no more updated by contrasting egocentric representations driven by perception. Recent neuroimaging studies are showing several structural and functional alterations in frame- and memory-related body-image-processing brain circuits that may support ALH.

Effects of low dose tryptophan depletion on emotional processing in dieters

Biased processing of ED-relevant stimuli (eg Fairburn, Shafran, & Cooper, 1999) and 5-HT function (Kaye, Fudge, & Paulus, 2009) are implicated in vulnerability to and the maintenance of eating disorders (EDs), but it is not known if these findings are connected: Could manipulating 5-HT function affect the processing of ED-relevant stimuli? To address this question we assessed emotional processing in female dieters (T+n=12, T-n=14) following acute low dose tryptophan depletion. ATD increased interference in the masked condition of the emotional Stroop to all negative emotional stimuli, in the absence of any other differences in emotional processing. These results suggest that ATD affects the processing of some negative (including ED-relevant) stimuli, and that reduced 5-HT function may be involved in some aspects of psychological vulnerability to EDs.

Serotonin transporter binding after recovery from bulimia nervosa

OBJECTIVE

Physiological and pharmacological studies indicate that altered brain serotonin (5-HT) activity could contribute to a susceptibility to develop appetitive and behavioral alterations that are characteristic of bulimia nervosa (BN).

METHOD

Eight individuals recovered from BN (REC BN) and eight healthy control women were scanned with [11C]DASB and positron emission tomography imaging of the 5-HT transporter (5-HTT). Logan graphical analysis was applied, and parametric binding potential (BP(nondisplaceable (ND)) ) images were generated. Voxel-by-voxel t-tests and a region of interest (ROI) analysis were conducted.

RESULTS

REC BN had significantly lower [11C]DASB BP(ND) in midbrain, superior and inferior cingulate and significantly higher [11C]DASB BP(ND) in anterior cingulate and superior temporal gyrus in the voxel-based analysis. ROI analysis indicated lower [11C]DASB BP(ND) in midbrain (p = .07), containing the dorsal raphe, in REC BN, consistent with our earlier studies.

DISCUSSION

These preliminary findings of a small-scale study confirm and extend previous data suggesting that ill and recovered BN have altered 5-HTT measures, which potentially contribute to BN symptomatology and/or differential responses to medication.

Neural responses to emotional faces in women recovered from anorexia nervosa

Impairments in emotional processing have been associated with anorexia nervosa. However, it is unknown whether neural and behavioural differences in the processing of emotional stimuli persist following recovery. The aim of this study was to investigate the neural processing of emotional faces in individuals recovered from anorexia nervosa compared with healthy controls. Thirty-two participants (16 recovered anorexia nervosa, 16 healthy controls) underwent a functional magnetic resonance imaging (fMRI) scan. Participants viewed fearful and happy emotional faces and indicated the gender of the face presented. Whole brain analysis revealed no significant differences between the groups to the contrasts of fear versus happy and vice versa. Region of interest analysis demonstrated no significant differences in the neural response to happy or fearful stimuli between the groups in the amygdala or fusiform gyrus. These results suggest that processing of emotional faces may not be aberrant after recovery from anorexia nervosa.

Thinking about eating food activates visual cortex with reduced bilateral cerebellar activation in females with anorexia nervosa: an fMRI study

Background

Women with anorexia nervosa (AN) have aberrant cognitions about food and altered activity in prefrontal cortical and somatosensory regions to food images. However, differential effects on the brain when thinking about eating food between healthy women and those with AN is unknown.

Methods

Functional magnetic resonance imaging (fMRI) examined neural activation when 42 women thought about eating the food shown in images: 18 with AN (11 RAN, 7 BPAN) and 24 age-matched controls (HC).

Results

Group contrasts between HC and AN revealed reduced activation in AN in the bilateral cerebellar vermis, and increased activation in the right visual cortex. Preliminary comparisons between AN subtypes and healthy controls suggest differences in cortical and limbic regions.

Conclusions

These preliminary data suggest that thinking about eating food shown in images increases visual and prefrontal cortical neural responses in females with AN, which may underlie cognitive biases towards food stimuli and ruminations about controlling food intake. Future studies are needed to explicitly test how thinking about eating activates restraint cognitions, specifically in those with restricting vs. binge-purging AN subtypes.

Subliminal food images compromise superior working memory performance in women with restricting anorexia nervosa

Prefrontal cortex (PFC) is dysregulated in women with restricting anorexia nervosa (RAN). It is not known whether appetitive non-conscious stimuli bias cognitive responses in those with RAN. Thirteen women with RAN and 20 healthy controls (HC) completed a dorsolateral PFC (DLPFC) working memory task and an anterior cingulate cortex (ACC) conflict task, while masked subliminal food, aversive and neutral images were presented. During the DLPFC task, accuracy was higher in the RAN compared to the HC group, but superior performance was compromised when subliminal food stimuli were presented: errors positively correlated with self-reported trait anxiety in the RAN group. These effects were not observed in the ACC task. Appetitive activation is intact and anxiogenic in women with RAN, and non-consciously interacts with working memory processes associated with the DLPFC. This interaction mechanism may underlie cognitive inhibition of appetitive processes that are anxiety inducing, in people with AN.

Reward processing in anorexia nervosa

Individuals with anorexia nervosa (AN) demonstrate a relentless engagement in behaviors aimed to reduce their weight, which leads to severe underweight status, and occasionally death. Neurobiological abnormalities, as a consequence of starvation are controversial: evidence, however, demonstrates abnormalities in the reward system of patients, and recovered individuals. Despite this, a unifying explanation for reward abnormalities observed in AN and their relevance to symptoms of the illness, remains incompletely understood. Theories explaining reward dysfunction have conventionally focused on anhedonia, describing that patients have an impaired ability to experience reward or pleasure. We review taste reward literature and propose that patients' reduced responses to conventional taste-reward tasks may reflect a fear of weight gain associated with the caloric nature of the tasks, rather than an impaired ability to experience reward. Consistent with this, we propose that patients are capable of 'liking' hedonic taste stimuli (e.g., identifying them), however, they do not 'want' or feel motivated for the stimuli in the same way that healthy controls report. Recent brain imaging data on more complex reward processing tasks provide insights into fronto-striatal neural circuit dysfunction related to altered reward processing in AN that challenges the relevance of anhedonia in explaining reward dysfunction in AN. In this way, altered activity of the anterior cingulate cortex and striatum could explain patients' pathological engagement in behaviors they consider rewarding (e.g., self-starvation) that are otherwise aversive or punishing, to those without the eating disorder. Such evidence for altered patterns of brain activity associated with reward processing tasks in patients and recovered individuals may provide important information about mechanisms underlying symptoms of AN, their future investigation, and the development of treatment approaches.

Anorexia nervosa--a noradrenergic dysregulation hypothesis

Anorexia nervosa manifests a wide range of features which cannot fully be explained on the basis of socio-cultural pressures to be thin, nor by starvation, nor dehydration. Evidence is emerging of a significant neurobiological contribution to its aetiology. However there has to date been no explanation for its pathogenesis that integrates the previously identified genetic, neurobiological and socio-cultural contributing factors. In this paper we propose an empirically-based hypothesis that genetically determined noradrenergic dysregulation, interacting with epigenetic factors, leads to high levels of anxiety, impaired neuroplasticity and regional cerebral hypoperfusion. These, in combination, lead to insula dysfunction. The resulting impairment in insula homuncular representation explains the pathognomonic body image distortion. This distortion, combined with high levels of body-focused anxiety, gives rise to intense dieting, noradrenergic precursor depletion, and initial reduction in anxiety. The subsequent rebound exacerbation of anxiety leads to a vicious cycle of maintenance. Novel treatment implications based on this hypothesis are briefly considered.

Poor cognitive flexibility in eating disorders: examining the evidence using the Wisconsin Card Sorting Task

BACKGROUND

People with eating disorders (ED) frequently present with inflexible behaviours, including eating related issues which contribute to the maintenance of the illness. Small scale studies point to difficulties with cognitive set-shifting as a basis. Using larger scale studies will lend robustness to these data.

METHODOLOGY/PRINCIPAL FINDINGS

542 participants were included in the dataset as follows: Anorexia Nervosa (AN) n = 171; Bulimia Nervosa (BN) n = 82; Recovered AN n = 90; Healthy controls (HC): n = 199. All completed the Wisconsin Card Sorting Task (WCST), an assessment that integrates multiple measurement of several executive processes concerned with problem solving and cognitive flexibility. The AN and BN groups performed poorly in most domains of the WCST. Recovered AN participants showed a better performance than currently ill participants; however, the number of preservative errors was higher than for HC participants.

CONCLUSIONS/SIGNIFICANCE

There is a growing interest in the diagnostic and treatment implications of cognitive flexibility in eating disorders. This large dataset supports previous smaller scale studies and a systematic review which indicate poor cognitive flexibility in people with ED.

Peripheral signals modifying food reward

The pleasure derived from eating may feel like a simple emotion, but the decision to eat, and perhaps more importantly what to eat, involves central pathways linking energy homeostasis and reward and their regulation by metabolic and endocrine factors. Evidence is mounting that modulation of the hedonic aspects of energy balance is under the control of peripheral neuropeptides conventionally associated with homeostatic appetite control. Here, we describe the significance of reward in feeding, the neural substrates underlying the reward pathway and their modification by peptides released into the circulation from peripheral tissues.

Neural substrates underlying interactions between appetite stress and reward

Neurobiological mechanisms that normally control food intake and energy expenditure can be overcome by environmental cues and by stress. Of particular importance is the influence of the mesolimbic reward pathway. In genetically susceptible individuals, problematic over-eating likely reflects a changing balance in the control exerted by homeostatic versus reward circuits that are strongly influenced by environmental factors such as stress. Both stress and activation of the reward pathway have been shown to increase food intake and promote a preference for palatable, high-energy foods. Recent research has focused on the important role of circulating and central neuropeptides that powerfully regulate the brain response to food cues. For example, ghrelin has a potent positive effect on the motivational aspects of food intake, and central oxytocin may be involved in satiety. Thus, the decision to eat, or indeed to over-eat, involves a complex integrated neurobiology that includes brain centres involved in energy balance, reward and stress and their regulation by metabolic and endocrine factors.

Discerning thoughts from feelings: the cognitive-affective division in eating disorders

This article delineates the phenomenon of "cognitive-affective division" in eating disorders, used to refer to the difficulty some patients face in translating what they "think" cognitively to what they "feel" emotionally. A clinical description of cognitive-affective division is first presented, drawing on existing research, before moving on to discuss psychological theories that might shed some light on this often-seen but seldom understood phenomenon. These include the role of emotion awareness and alexithymia, cognitive and emotional development, and neuropsychological theories. We discuss implications for treatment and further research of the cognitive-affective division in eating disorders.

Altered implicit category learning in anorexia nervosa

OBJECTIVE

Recent research has identified specific cognitive deficits in patients with anorexia nervosa (AN), including impairment in executive functioning and attention. Another such cognitive process, implicit category learning has been less studied in AN. This study examined whether implicit category learning is impaired in AN.

METHOD

Twenty-one women diagnosed with AN and 19 control women (CW) were administered an implicit category learning task in which they were asked to categorize simple perceptual stimuli (Gabor patches) into one of two categories. Category membership was based on a linear integration (i.e., an implicit task) of two stimulus dimensions (orientation and spatial frequency of the stimulus).

RESULTS

AN individuals were less accurate on implicit category learning relative to age-matched CW. Model-based analyses indicated that, even when AN individuals used the appropriate (i.e., implicit) strategy they were still impaired relative to CW who also used the same strategy. In addition, task performance in AN patients was worse the higher they were in self-reported novelty seeking and the lower they were in sensitivity to punishment.

CONCLUSIONS

These results indicate that AN patients have implicit category learning deficits, and given this type of learning is thought to be mediated by striatal dopamine pathways, AN patients may have deficits in these neural systems. The finding of significant correlations with novelty seeking and sensitivity to punishment suggests that feedback sensitivity is related to implicit learning in AN.

Eating-related anxiety in individuals with eating disorders

Although previous research has supported the importance of anxiety as an etiological and maintenance factor for eating disorders, the specific mechanisms are not well understood. The role of anxiety in the context of eating behavior is especially unclear. The purpose of this study was to identify anxiety-eliciting eating situations and anxiety management strategies patients use to mitigate anxiety experienced in the context of eating as determined by diagnostic groups and symptom patterns. Fifty-three eating disorder outpatients were administered the Eating and Anxiety Questionnaire (EAQ) and the Eating Disorder Diagnostic Scale. Ratings indicated significant anxiety in most eating situations, whereas management strategies were more limited yet regularly employed. Factor analysis of the EAQ revealed a 6-factor solution for anxiety management strategies and a 4-factor solution for anxiety-eliciting situations. These results indicate patients with eating disorders report high levels of anxiety associated with eating behaviors but utilize limited yet consistent anxiety management strategies. Effective intervention strategies for managing eating-related anxiety should be incorporated into treatment and may need to be specified for different diagnostic subgroups.

Parental expressed emotion of adolescents with anorexia nervosa: outcome in family-based treatment

OBJECTIVE

The purpose of this study was to determine the relationship between expressed emotion (EE) and outcome in family-based treatment (FBT) for anorexia nervosa (AN).

METHOD

Eighty-six adolescents with AN participated in an RCT comparing two doses of FBT. Seventy-nine of these patients and their parents participated in a structured interview, from which EE ratings were made at baseline. Parents were compared on five subscales of EE as well as overall level of EE (high vs. low).

RESULTS

Overall EE levels were low with 32.9% of families presenting as High EE at baseline. Ratings of baseline warmth for both mothers (p = .014) and fathers (p = .037) were related to good outcome at end-of-treatment.

DISCUSSION

EE in parents of adolescents with AN is remarkably low. Notwithstanding, parental warmth may be a predictor of good outcome.

Psychometric Properties of the Eating Disorder Inventory in Clinical and Nonclinical Populations in Taiwan

Objective. To examine psychometric properties and investigate factor structures of the Mandarin Chinese version of the Eating Disorder Inventory (C-EDI). Method. The Mandarin C-EDI and other self-administered questionnaires were completed by a group of female eating disorder (ED) patients ( n = 551) and a group of female nursing students ( n = 751). Internal consistency, and convergent and discriminant validities were evaluated. Exploratory and confirmatory factor analyses were conducted to examine the construct validity of the Mandarin C-EDI. Results. The Mandarin C-EDI had good internal consistency and convergent and discriminant validities. With a few exceptions, the original clinically derived eight EDI subscales were clearly identified and the factorial validity of the first-order eight-factor structure and the second-order two-factor structure showed an acceptable degree of fit to our empirical data in clinical patients. Discussion. The findings suggest that the Mandarin C-EDI is a valid tool for clinical use in Taiwan.

Neuroscience and eating disorders: the allocentric lock hypothesis

Evidence from psychology and neuroscience indicates that our spatial experience, including the bodily one, involves the integration of different sensory inputs within two different reference frames egocentric (body as reference of first-person experience) and allocentric (body as object in the physical world). Even if functional relations between these two frames are usually limited, they influence each other during the interaction between long- and short-term memory processes in spatial cognition. If, for some reasons, this process is impaired, the egocentric sensory inputs are no more able to update the contents of the allocentric representation of the body: the subject is locked to it. In the presented perspective, subjects with eating disorders are locked to an allocentric representation of their body, stored in long-term memory (allocentric lock). A significant role in the locking may be played by the medial temporal lobe, and in particular by the connection between the hippocampal complex and amygdala. The differences between exogenous and endogenous causes of the lock may also explain the difference between bulimia nervosa and anorexia nervosa.

Restraint of appetite and reduced regional brain volumes in anorexia nervosa: a voxel-based morphometric study

BACKGROUND

Previous Magnetic Resonance Imaging (MRI) studies of people with anorexia nervosa (AN) have shown differences in brain structure. This study aimed to provide preliminary extensions of this data by examining how different levels of appetitive restraint impact on brain volume.

METHODS

Voxel based morphometry (VBM), corrected for total intracranial volume, age, BMI, years of education in 14 women with AN (8 RAN and 6 BPAN) and 21 women (HC) was performed. Correlations between brain volume and dietary restraint were done using Statistical Package for the Social Sciences (SPSS).

RESULTS

Increased right dorsolateral prefrontal cortex (DLPFC) and reduced right anterior insular cortex, bilateral parahippocampal gyrus, left fusiform gyrus, left cerebellum and right posterior cingulate volumes in AN compared to HC. RAN compared to BPAN had reduced left orbitofrontal cortex, right anterior insular cortex, bilateral parahippocampal gyrus and left cerebellum. Age negatively correlated with right DLPFC volume in HC but not in AN; dietary restraint and BMI predicted 57% of variance in right DLPFC volume in AN.

CONCLUSIONS

In AN, brain volume differences were found in appetitive, somatosensory and top-down control brain regions. Differences in regional GMV may be linked to levels of appetitive restraint, but whether they are state or trait is unclear. Nevertheless, these discrete brain volume differences provide candidate brain regions for further structural and functional study in people with eating disorders.