Functional neuroimaging in anorexia nervosa: A clinical approach

Hypothalamic subregion alterations in anorexia nervosa and obesity: Association with appetite-regulating hormone levels

OBJECTIVE

Anorexia nervosa (AN) and obesity are weight-related disorders with imbalances in energy homeostasis that may be due to hormonal dysregulation. Given the importance of the hypothalamus in hormonal regulation, we aimed to identify morphometric alterations to hypothalamic subregions linked to these conditions and their connection to appetite-regulating hormones.

METHODS

Structural magnetic resonance imaging (MRI) was obtained from 78 patients with AN, 27 individuals with obesity and 100 normal-weight healthy controls. Leptin, ghrelin, and insulin blood levels were measured in a subsample of each group. An automated segmentation method was used to segment the hypothalamus and its subregions. Volumes of the hypothalamus and its subregions were compared between groups, and correlational analysis was employed to assess the relationship between morphometric measurements and appetite-regulating hormone levels.

RESULTS

While accounting for total brain volume, patients with AN displayed a smaller volume in the inferior-tubular subregion (ITS). Conversely, obesity was associated with a larger volume in the anterior-superior, ITS, posterior subregions (PS), and entire hypothalamus. There were no significant volumetric differences between AN subtypes. Leptin correlated positively with PS volume, whereas ghrelin correlated negatively with the whole hypothalamus volume in the entire cohort. However, appetite-regulating hormone levels did not mediate the effects of body mass index on volumetric measures.

CONCLUSION

Our results indicate the importance of regional structural hypothalamic alterations in AN and obesity, extending beyond global changes to brain volume. Furthermore, these alterations may be linked to changes in hormonal appetite regulation. However, given the small sample size in our correlation analysis, further analyses in a larger sample size are warranted.

PUBLIC SIGNIFICANCE

Using an automated segmentation method to investigate morphometric alterations of hypothalamic subregions in AN and obesity, this study provides valuable insights into the complex interplay between hypothalamic alterations, hormonal appetite regulation, and body weight, highlighting the need for further research to uncover underlying mechanisms.

The multisensory mind: a systematic review of multisensory integration processing in Anorexia and Bulimia Nervosa

Individuals with Anorexia Nervosa and Bulimia Nervosa present alterations in the way they experience their bodies. Body experience results from a multisensory integration process in which information from different sensory domains and spatial reference frames is combined into a coherent percept. Given the critical role of the body in the onset and maintenance of both Anorexia Nervosa and Bulimia Nervosa, we conducted a systematic review to examine multisensory integration abilities of individuals affected by these two conditions and investigate whether they exhibit impairments in crossmodal integration. We searched for studies evaluating crossmodal integration in individuals with a current diagnosis of Anorexia Nervosa and Bulimia Nervosa as compared to healthy individuals from both behavioral and neurobiological perspectives. A search of PubMed, PsycINFO, and Web of Sciences databases was performed to extract relevant articles. Of the 2348 studies retrieved, 911 were unique articles. After the screening, 13 articles were included. Studies revealed multisensory integration abnormalities in patients affected by Anorexia Nervosa; only one included individuals with Bulimia Nervosa and observed less severe impairments compared to healthy controls. Overall, results seemed to support the presence of multisensory deficits in Anorexia Nervosa, especially when integrating interoceptive and exteroceptive information. We proposed the Predictive Coding framework for understanding our findings and suggested future lines of investigation.

The Effect of Transcranial Direct Current Stimulation (tDCS) on Anorexia Nervosa: A Narrative Review

(1) Introduction: Anorexia nervosa (AN) is a severe, debilitating disease with high incidence and high mortality. The methods of treatment used so far are moderately effective. Evidence from neuroimaging studies helps to design modern methods of therapy. One of them is transcranial direct current stimulation (tDCS), a non-invasive brain neuromodulation technique. (2) Methods: The purpose of this narrative review is to bring together all studies investigating the use of tDCS in the treatment of AN and to evaluate its effect and efficiency. Searches were conducted in the Pubmed/Medline, Research Gate, and Cochrane databases. (3) Results: The literature search resulted in five articles. These studies provide preliminary evidence that tDCS has the potential to alter eating behaviour, body weight, and food intake. Additionally, tDCS reduced symptoms of depression. Throughout all trials, stimulation targeted the left dorsolateral prefrontal cortex (DLPFC). Although the number of studies included is limited, attempts were made to elucidate the potential mechanisms underlying tDCS action in individuals with AN. Recommendations for future tDCS research in AN were issued. (4) Conclusions: The included studies have shown that tDCS stimulation of the left DLPFC has a positive effect on AN clinical symptoms and may improve them, as measured by various assessment measures. It is important to conduct more in-depth research on the potential benefits of using tDCS for treating AN. This should entail well-designed studies incorporating advanced neuroimaging techniques, such as fMRI. The aim is to gain a better understanding of how tDCS works in AN.

Association of emotion recognition ability and interpersonal emotional competence in anorexia nervosa: A study with a multimodal dynamic task

OBJECTIVE

Interpersonal difficulties are evidenced in Anorexia Nervosa (AN) and are thought to contribute to disease onset and maintenance, however, research in the framework of emotional competence is currently limited. Previous studies have often only used static images for emotion recognition tasks, and evidence is lacking on the relationships between performance-based emotional abilities and self-reported intra- and interpersonal emotional traits. This study aimed to test multimodal dynamic emotion recognition ability in AN and analyze its correlation with the psychometric scores of self- and other-related emotional competence.

METHOD

A total of 268 participants (128 individuals with AN and 140 healthy controls) completed the Geneva Emotion Recognition Test, the Profile of Emotional Competence, the Reading the Mind in the Eyes Test, and measures of general and eating psychopathology. Scores were compared between the two groups. Linear mixed effects models were utilized to examine the relationship between emotion recognition ability and self-reported measures and clinical variables.

RESULTS

Individuals with AN showed significantly poorer recognition of emotions of both negative and positive valence and significantly lower scores in all emotional competence dimensions. Beside emotion type and group, linear mixed models evidenced significant effects of interpersonal comprehension on emotion recognition ability.

DISCUSSION

Individuals with AN show impairment in multimodal emotion recognition and report their difficulties accordingly. Notably, among all emotional competence dimensions, interpersonal comprehension emerges as a significant correlate to emotion recognition in others, and could represent a specific area of intervention in the treatment of individuals with AN.

PUBLIC SIGNIFICANCE

In this study, we evidence that the ability to recognize the emotions displayed by others is related to the level of interpersonal emotional competence reported by individuals with anorexia nervosa. This result helps in understanding the social impairments in people with anorexia nervosa and could contribute to advancements in the application of the training of emotional competence in the treatment of this disorder.

Bridging cognitive, phenomenological and psychodynamic approaches to eating disorders

Cognitive, psychodynamic, and phenomenological scholars converged their attention on abnormal bodily phenomena as the core psychopathological feature of eating disorders (EDs). While cognitive approaches focus their attention on a need for "objective" (i.e., observable, measurable) variables (including behaviours and distorted cognitions), the phenomenological exploration typically targets descriptions of persons' lived experience. According to a new emerging phenomenological perspective, the classic behavioural and cognitive symptoms of EDs should be considered as epiphenomena of a deeper core represented by a disorder of the embodiment. The cognitive-behavioural model is the most studied and, up till now, clinically efficacious treatment for EDs. However, as any coherent and scientifically grounded model, it presents some limitations in its application. Numerous patients report a chronic course, do not respond to treatment and develop a personality structure based on pathological eating behaviours, since "being anorexic" becomes a new identity for the person. Furthermore, the etiopathogenetic trajectory of EDs influences the treatment response: for example, patients reporting childhood abuse or maltreatment respond differently to cognitive-behavioural therapy. To obtain a deeper comprehension of these disorders, it seems important to shift attention from abnormal eating behaviours to more complex and subtle psycho(patho)logical features, especially experiential ones. This characterisation represents the unavoidable premise for the identification of new therapeutic targets and consequently for an improvement of the outcome of these severe disorders. Thus, the present review aims to provide an integrated view of cognitive, psychodynamic, and phenomenological perspectives on EDs, suggesting new therapeutic targets and intervention strategies based on this integrated model. Level of Evidence: Level V.Level of evidence Level V: Opinions of authorities, based on descriptive studies, narrative reviews, clinical experience, or reports of expert committees.

Affective cognition in eating disorders: a systematic review and meta-analysis of the performance on the "Reading the Mind in the Eyes" Test

BACKGROUND

The Reading the Mind in the Eyes Test (RMET) is listed in the National Institute of Mental Health's Research Domain Criteria as a tool apt to measure the understanding of others' mental states. People diagnosed with anorexia nervosa (AN) showed poorer performances on the RMET than healthy controls. Less data are available concerning other eating disorders.

METHODS

Systematic review of four major databases from inception to July 15, 2021 following the PRISMA guidelines. Meta-analysis of cross-sectional observational studies comparing the scores of the RMET between patients with eating disorders and age- and-gender matched control groups.

RESULTS

Out of 21 studies, we retrieved 29 independent samples of patients diagnosed with an eating disorder. Patients with active AN (n = 580) showed worse performances on the RMET than controls (n = 1019). Year of publication accounted for 61% of the (substantial: I² = 81%) heterogeneity in the meta-analysis. Earlier studies were more likely to find worse performances on the RMET of patients with active AN than later studies. Patients with bulimia nervosa (n = 185) performed poorly as compared to controls (n = 249), but the results were not statistically significant on the random-effect model. Obese patients with binge-eating disorder (n = 54) did not differ on the RMET from obese controls (n = 52). Patients with eating disorder not otherwise specified (n = 57) showed minimal differences compared to controls (n = 96). Study quality was good in six studies only.

CONCLUSIONS

Patients with eating disorders do not suffer from an impaired understanding of others' mental states, except for a still-to-be-identified subgroup of patients with active AN.

LEVEL OF EVIDENCE

I, systematic review and meta-analysis.

Association between high levels of body-esteem and increased degree of midcingulate cortex global connectivity: A resting-state fMRI study

Multiple neuroimaging studies have examined the neural underpinnings of body image disturbances in patients with eating disorders. However, key brain regions related to body image, such as body-esteem (BE), among healthy individuals are understudied. Given the extremely crucial role of BE in eating behaviors and physical and mental health, the current study conducted data-driven analysis and characterized the neurobiological correlates of BE with the network properties of the resting brain using the voxel-wise degree centrality (DC) measures of resting-state functional magnetic resonance imaging (rs-fMRI) data and seed-based resting-state functional connectivity (RSFC). A total of 694 healthy young adults (females = 474, mean age = 18.38 years, range = 17-22) underwent rs-fMRI, and completed the Body-Esteem Scale for Adolescents and Adults, the Eating Disorder Diagnosis Scale, and the Restraint Scale. After correcting for differences in age, gender, body mass index, and head motion, whole-brain correlation analyses revealed that a high level of BE was associated with increased DC within the right midcingulate cortex (MCC) and subsequent high levels of MCC-based RSFC strengths. Furthermore, MCC connectivity patterns related to BE were inversely associated with disordered eating behaviors. These findings suggest that adaptive cognitive and emotional regulation (i.e., self-evaluation and emotion based on body image) may explain the potential relationship between MCC connectivity patterns and BE to a certain extent. As such, future studies should investigate these interesting possibilities.

Brain activation and connectivity in anorexia nervosa and body dysmorphic disorder when viewing bodies: relationships to clinical symptoms and perception of appearance

Anorexia nervosa (AN) and body dysmorphic disorder (BDD) are characterized by distorted perception of appearance, yet no studies have directly compared the neurobiology associated with body perception. We compared AN and BDD in brain activation and connectivity in relevant networks when viewing images of others' bodies and tested their relationships with clinical symptoms and subjective appearance evaluations. We acquired fMRI data from 64 unmedicated females (20 weight-restored AN, 23 BDD, 21 controls) during a matching task using unaltered or spatial-frequency filtered photos of others' bodies. Using general linear model and independent components analyses we compared brain activation and connectivity in visual, striatal, and parietal networks and performed univariate and partial least squares multivariate analyses to investigate relationships with clinical symptoms and appearance evaluations. AN and BDD showed partially overlapping patterns of hyperconnectivity in the dorsal visual network and hypoconnectivity in parietal network compared with controls. BDD, but not AN, demonstrated hypoactivity in dorsal visual and parietal networks compared to controls. Further, there were significant activity and connectivity differences between AN and BDD in both networks. In both groups, activity and/or connectivity were associated with symptom severity and appearance ratings of others' bodies. Thus, AN and BDD demonstrate both distinct and partially-overlapping aberrant neural phenotypes involved in body processing and visually encoding global features. Nevertheless, in each disorder, aberrant activity and connectivity show relationships to clinically relevant symptoms and subjective perception. These results have implications for understanding distinct and shared pathophysiology underlying perceptual distortions of appearance and may inform future novel treatment strategies.

Awareness of Dystonic Posture in Patients With Cervical Dystonia

Background

Cervical dystonia (CD) is a focal dystonia characterized by sensorimotor integration abnormalities and proprioceptive dysfunction. Since proprioception is essential for bodily awareness, we hypothesized that CD patients may have an impairment in dystonic posture awareness. More information on this issue could be useful to better understand whether dystonic posture affects bodily perception in CD and could help in the development of specific rehabilitation strategies based on proprioceptive input manipulation to restore bodily awareness.

Objectives

The aim of our study was to investigate dystonic posture and head tremor awareness in CD patients by comparing evaluations performed by CD patients with those performed by a neurologist expert in movement disorders.

Methods

We enrolled 25 CD patients. We investigated dystonic posture and head tremor awareness in CD patients using a standardized protocol in which patients were asked to describe the type of dystonic pattern, both while viewing standardized images of different CD subtypes (torticollis, laterocollis, anterocollis, and retrocollis) and after watching a video recording of their dystonic posture and head tremor.

Results

We found that 72% of CD patients correctly recognized their dystonic posture when viewing standardized images, whereas 84% of CD patients were able to identify their dystonic pattern when watching a video recording of themselves. CD patients also displayed a preserved awareness of their head tremor. We did not find any associations between dystonic pattern awareness and clinical or demographic features.

Conclusion

Contrary to our hypothesis, the majority of CD patients have a preserved awareness of their dystonic pattern and tremor.

Functional MRI investigation of verbal working memory in adults with anorexia nervosa

Literature regarding verbal working memory (vWM) in anorexia nervosa (AN) has been inconsistent due to a misunderstanding of the key components of vWM and introduction of confounding stimuli. Furthermore, there are no studies looking at how brain function in people with AN relates to vWM performance. The present study used functional magnetic resonance imaging (fMRI) with a letter n-back paradigm to study the effect of increasing vWM task difficulty on cortical functioning in the largest AN sample to date (n = 31). Although the AN group had low BMI and higher anxious and depressive symptomology compared to age-matched controls (HC), there were no between-group differences in accuracy and speed at any task difficulty. fMRI data revealed no regions exhibiting significant differences in activation when groups were compared at each difficulty separately and no regions showing group x condition interaction. Although there was a trend towards lower accuracy as duration of illness increased, this was not correlated with activity in regions associated with vWM. These findings indicate that vWM in AN is as efficient and performed using the same cognitive strategy as HC, and that there may not be a need for therapies to pursue remediation of this particular neurocognitive faculty.

Looking at my body. Similarities and differences between anorexia nervosa patients and controls in body image visual processing

Background

Body image distortion is a core symptom of eating disorders. Functional magnetic resonance imaging (fMRI) studies on body image processing, described different patterns of neural response, mainly involving the inferior and superior parietal lobules, and the dorsolateral prefrontal cortex (DLPFC), with conflicting results.

Methods

The neural response to the view of their own body pictures (normal size and distorted) was evaluated in 18 female anorexia nervosa (AN) restricting type patients, and in 19 healthy female subjects (HC) using fMRI. Clinical assessment was performed by means of the structured clinical interview for DSM-IV and self-reported questionnaires.

Results

In response to the body image distortion, patients and controls showed an inverse pattern of activation, with the widest extent of activation in the oversize condition in AN, while in the undersize condition in HC. AN and HC showed a similar pattern of neural response to the view of their own body, with an increased activation in the extrastriate body area, superior and inferior parietal lobule and prefrontal areas, although the extent of activation in HC was more limited as compared with AN patients. Increased activity in AN patients, compared with HC, was observed in the DLPFC in response to the oversized body picture and a significant correlation was found in AN patients between DLPFC activation and eating disorder psychopathology.

Conclusions

Our findings suggest the existence of a continuum from normalcy to pathology in neural response to body image, and confirm the clinical relevance of body image distortion in AN, reinforcing the key role of attentive, executive and self-evaluation networks in AN visual processing of own distorted body image.

Deficits in response inhibition on varied levels of demand load in anorexia nervosa: an event-related potentials study

PURPOSE

The aim of the present study was to investigate the executive function of inhibitory control in anorexia nervosa (AN), which is considered as an underlying pathophysiology of restricting eating.

METHODS

In this work, we examined the function of response inhibition in 27 unmedicated AN patients and 30 healthy controls (HC) using stop-signal tasks with different demand loads. Two event-related potentials (ERP) during the stop-signal tasks, N2 and P300, were compared between the AN and HC groups.

RESULTS

We found attenuated P300 amplitudes and delayed N2 latencies in AN patients across all three demand loads compared to HCs. We also found significant interaction between group and level of demand load. N2 latencies were prolonged when the inhibitory demand was lower in the AN group, whereas no differences in N2 latencies were found across different demand loads in HCs.

CONCLUSIONS

Taken together, altered P300 amplitudes and N2 latencies may be associated with impaired response inhibition in AN patients. In particular, alterations of fronto-central N2 activations were demand-related, which might contribute to an aberrant inhibitory control process in AN.

LEVEL OF EVIDENCE

Level II, controlled trial without randomization.

Differentiating weight-restored anorexia nervosa and body dysmorphic disorder using neuroimaging and psychometric markers

Anorexia nervosa (AN) and body dysmorphic disorder (BDD) are potentially life-threatening conditions whose partially overlapping phenomenology—distorted perception of appearance, obsessions/compulsions, and limited insight—can make diagnostic distinction difficult in some cases. Accurate diagnosis is crucial, as the effective treatments for AN and BDD differ. To improve diagnostic accuracy and clarify the contributions of each of the multiple underlying factors, we developed a two-stage machine learning model that uses multimodal, neurobiology-based, and symptom-based quantitative data as features: task-based functional magnetic resonance imaging data using body visual stimuli, graph theory metrics of white matter connectivity from diffusor tensor imaging, and anxiety, depression, and insight psychometric scores. In a sample of unmedicated adults with BDD (n = 29), unmedicated adults with weight-restored AN (n = 24), and healthy controls (n = 31), the resulting model labeled individuals with an accuracy of 76%, significantly better than the chance accuracy of 35% (p^<10‑4). In the multivariate model, reduced white matter global efficiency and better insight were associated more with AN than with BDD. These results improve our understanding of the relative contributions of the neurobiological characteristics and symptoms of these disorders. Moreover, this approach has the potential to aid clinicians in diagnosis, thereby leading to more tailored therapy.

Insula H-coil deep transcranial magnetic stimulation in severe and enduring anorexia nervosa (SE-AN): a pilot study

INTRODUCTION

Anorexia nervosa (AN) is a complex disorder of unknown etiology, characterized by obsessions and compulsions around body shape, weight, and calorie intake. In the course of AN, 10%-30% will recover, while the rest will develop a treatment-resistant course with a high mortality rate due to AN-related complications. The insula is a region in the brain of considerable interest to its role in gustatory modulation, feeding behavior, and processing of interoceptive stimuli.

OBJECTIVE

Recent advances in the neurophysiology of AN suggest insula dysfunction as a potential biomarker for people with severe and enduring AN (SE-AN). Deep transcranial magnetic stimulation (dTMS) is of particular interest in SE-AN because of its ability to target deep areas of the brain.

DESIGN

We conducted a pilot study to investigate the feasibility and safety of insula dTMS in subjects with SE-AN.

RESULTS

We found that dTMS is a safe and well-tolerated treatment. We also found a reduction in AN-related obsessions and compulsions, as well as depression and anxiety scores from baseline to the end of the trial. Due to small sample size, the results of this study should be interpreted with great caution.

DISCUSSION

The results suggest that dTMS is safe and well tolerated and may be of some clinical interest in patients with SE-AN. However, to determine the true efficacy of dTMS for SE-AN, there is a need to conduct a randomized controlled trial comparing real versus sham dTMS in a larger number of AN subjects.

Contributions of medial prefrontal cortex to decision making involving risk of punishment

The prefrontal cortex (PFC) plays an important role in several forms of cost-benefit decision making. Its contributions to decision making under risk of explicit punishment, however, are not well understood. A rat model was used to investigate the role of the medial PFC (mPFC) and its monoaminergic innervation in a Risky Decision-making Task (RDT), in which rats chose between a small, "safe" food reward and a large, "risky" food reward accompanied by varying probabilities of mild footshock punishment. Inactivation of mPFC increased choice of the large, risky reward when the punishment probability increased across the session ("ascending RDT"), but decreased choice of the large, risky reward when the punishment probability decreased across the session ("descending RDT"). In contrast, enhancement of monoamine availability via intra-mPFC amphetamine reduced choice of the large, risky reward only in the descending RDT. Systemic administration of amphetamine reduced choice of the large, risky reward in both the ascending and descending RDT; however, this reduction was not attenuated by concurrent mPFC inactivation, indicating that mPFC is not a critical locus of amphetamine's effects on risk taking. These findings suggest that mPFC plays an important role in adapting choice behavior in response to shifting risk contingencies, but not necessarily in risk-taking behavior per se.

Neuroendocrinology and brain imaging of reward in eating disorders: A possible key to the treatment of anorexia nervosa and bulimia nervosa

Anorexia nervosa and bulimia nervosa are severe eating disorders whose etiopathogenesis is still unknown. Clinical features suggest that eating disorders may develop as reward-dependent syndromes, since eating less food is perceived as rewarding in anorexia nervosa while consumption of large amounts of food during binge episodes in bulimia nervosa aims at reducing the patient's negative emotional states. Therefore, brain reward mechanisms have been a major focus of research in the attempt to contribute to the comprehension of the pathophysiology of these disorders. Structural brain imaging data provided the evidence that brain reward circuits may be altered in patients with anorexia or bulimia nervosa. Similarly, functional brain imaging studies exploring the activation of brain reward circuits by food stimuli as well as by stimuli recognized to be potentially rewarding for eating disordered patients, such as body image cues or stimuli related to food deprivation and physical hyperactivity, showed several dysfunctions in ED patients. Moreover, very recently, it has been demonstrated that some of the biochemical homeostatic modulators of eating behavior are also implicated in the regulation of food-related and non-food-related reward, representing a possible link between the aberrant behaviors of ED subjects and their hypothesized deranged reward processes. In particular, changes in leptin and ghrelin occur in patients with anorexia or bulimia nervosa and have been suggested to represent not only homeostatic adaptations to an altered energy balance but to contribute also to the acquisition and/or maintenance of persistent starvation, binge eating and physical hyperactivity, which are potentially rewarding for ED patients. On the basis of such findings new pathogenetic models of EDs have been proposed, and these models may provide new theoretical basis for the development of innovative treatment strategies, either psychological and pharmacological, with the aim to improve the outcomes of so severe disabling disorders.

A core eating network and its modulations underlie diverse eating phenomena

We propose that a core eating network and its modulations account for much of what is currently known about the neural activity underlying a wide range of eating phenomena in humans (excluding homeostasis and related phenomena). The core eating network is closely adapted from a network that Kaye, Fudge, and Paulus (2009) proposed to explain the neurocircuitry of eating, including a ventral reward pathway and a dorsal control pathway. In a review across multiple literatures that focuses on experiments using functional Magnetic Resonance Imaging (fMRI), we first show that neural responses to food cues, such as food pictures, utilize the same core eating network as eating. Consistent with the theoretical perspective of grounded cognition, food cues activate eating simulations that produce reward predictions about a perceived food and potentially motivate its consumption. Reviewing additional literatures, we then illustrate how various factors modulate the core eating network, increasing and/or decreasing activity in subsets of its neural areas. These modulating factors include food significance (palatability, hunger), body mass index (BMI, overweight/obesity), eating disorders (anorexia nervosa, bulimia nervosa, binge eating), and various eating goals (losing weight, hedonic pleasure, healthy living). By viewing all these phenomena as modulating a core eating network, it becomes possible to understand how they are related to one another within this common theoretical framework. Finally, we discuss future directions for better establishing the core eating network, its modulations, and their implications for behavior.

Functional brain alterations in anorexia nervosa: a scoping review

BACKGROUND

Neuroimaging allows for the identification of brain abnormalities and alterations that are associated with anorexia nervosa (AN). We performed a scoping review to map out the extent and nature of recent research activity on functional magnetic resonance imaging (fMRI) in individuals diagnosed with, or recovered from, AN (AN-REC).

MAIN TEXT

A literature search of PubMed, Psychinfo and Embase was conducted using the search terms "anorexia nervosa" AND "functional magnetic resonance imaging." We included fMRI studies that involved a comparison between individuals with AN or AN-REC and healthy controls published in English language between 2010 and 2015. A total of 49 papers were included, regardless of the experimental stimuli or paradigm.

CONCLUSIONS

Findings varied considerably across studies, reflecting methodological differences in study design, such as sample differences and experimental paradigms. Collectively, studies published during the past five years suggest altered activation in regions related to the fronto-striato and the limbic circuits, which are theorized to have an important role in the pathophysiology of AN.

n-back task performance and corresponding brain-activation patterns in women with restrictive and bulimic eating-disorder variants: preliminary findings

Eating disorder (ED) variants characterized by "binge-eating/purging" symptoms differ from "restricting-only" variants along diverse clinical dimensions, but few studies have compared people with these different eating-disorder phenotypes on measures of neurocognitive function and brain activation. We tested the performances of 19 women with "restricting-only" eating syndromes and 27 with "binge-eating/purging" variants on a modified n-back task, and used functional magnetic resonance imaging (fMRI) to examine task-induced brain activations in frontal regions of interest. When compared with "binge-eating/purging" participants, "restricting-only" participants showed superior performance. Furthermore, in an intermediate-demand condition, "binge-eating/purging" participants showed significantly less event-related activation than did "restricting-only" participants in a right posterior prefrontal region spanning Brodmann areas 6-8-a region that has been linked to planning of motor responses, working memory for sequential information, and management of uncertainty. Our findings suggest that working memory is poorer in eating-disordered individuals with binge-eating/purging behaviors than in those who solely restrict food intake, and that observed performance differences coincide with interpretable group-based activation differences in a frontal region thought to subserve planning and decision making.

Eating disorder psychopathology, brain structure, neuropsychological correlates and risk mechanisms in very preterm young adults

This study investigates the prevalence of eating disorder (ED) psychopathology, neuropsychological function, structural brain correlates and risk mechanisms in a prospective cohort of very preterm (VPT) young adults. We assessed ED psychopathology and neuropsychological correlates in 143 cohort individuals born at <33 weeks of gestation. Structural brain correlates and risk factors at birth, in childhood and adolescence, were investigated using prospectively collected data throughout childhood/adolescence. VPT-born individuals had high levels of ED psychopathology at age 21 years. Executive function did not correlate with ED symptomatology. VPT adults presenting with ED psychopathology had smaller grey matter volume at age 14/15 years in the left posterior cerebellum and smaller white matter volume in the fusiform gyrus bilaterally, compared with VPT adults with no ED psychopathology. Caesarean delivery predicted engaging in compensatory behaviours, and severe eating difficulty at age 14 years predicted ED symptomatology in young adulthood. VPT individuals are at risk for ED symptomatology, with evidence of associated structural alterations in posterior brain regions. Further prospective studies are needed to clarify the pathways that lead from perinatal/obstetric complications to ED and relevant neurobiological mechanisms. © 2015 The Authors. European Eating Disorders Review published by John Wiley &Sons, Ltd.

Obsessive-compulsivity and working memory are associated with differential prefrontal cortex and insula activation in adolescents with a recent diagnosis of an eating disorder

The role of rumination at the beginning of eating disorder (ED) is not well understood. We hypothesised that impulsivity, rumination and restriction could be associated with neural activity in response to food stimuli in young individuals with eating disorders (ED). We measured neural responses with functional magnetic resonance imaging (fMRI), tested working memory (WM) and administered the eating disorders examination questionnaire (EDE-Q), Barratt impulsivity scale (BIS-11) and obsessive-compulsive inventory (OCI-R) in 15 adolescent females with eating disorder not otherwise specified (EDNOS) (mean age 15 years) and 20 age-matched healthy control females. We found that EDNOS subjects had significantly higher scores on the BIS 11, EDE-Q and OCI-R scales. Significantly increased neural responses to food images in the EDNOS group were observed in the prefrontal circuitry. OCI-R scores in the EDNOS group also significantly correlated with activity in the prefrontal circuitry and the cerebellum. Significantly slower WM responses negatively correlated with bilateral superior frontal gyrus activity in the EDNOS group. We conclude that ruminations, linked to WM, are present in adolescent females newly diagnosed with EDNOS. These may be risk factors for the development of an eating disorder and may be detectable before disease onset.

Social insecurity in relation to orbitofrontal activity in patients with eating disorders: a near-infrared spectroscopy study

BACKGROUND

Functional neuroimaging techniques are widely used to elucidate changes in brain activity, and various questionnaires are used to investigate psychopathological features in patients with eating disorders (ED). It is well known that social skills and interpersonal difficulties are strongly associated with the psychopathology of patients with ED. However, few studies have examined the association between brain activity and social relationships in patients with ED, particularly in patients with extremely low body weight.

METHODS

In this study, 22-channel near-infrared spectroscopy was used to quantify regional hemodynamic changes during a letter fluency task (LFT) in 20 female patients with ED with a mean body mass index of 14.0 kg/m(2) and 31 female controls (CTLs). Symptoms were assessed using the Eating Disorder Inventory-2 and Beck Depression Inventory. We hypothesized that frontal activity in patients with ED would be lower than in CTLs and would show different correlations with psychopathological features compared with CTLs.

RESULTS

The LFT performance and score on the social insecurity subscale of the Eating Disorder Inventory-2 were significantly higher in the ED group than in the CTL group. The mean change in oxygenated hemoglobin (oxy-Hb) in bilateral frontal regions during the LFT was significantly smaller in the ED group than in the CTL group. Social insecurity score was positively correlated with the concentration of oxy-Hb in the bilateral orbitofrontal cortex in the ED group but not in the CTL group.

CONCLUSIONS

These results suggest that activity of the orbitofrontal cortex is associated with social insecurity and disturbed in patients with ED. Therefore, disturbed orbitofrontal cortex activity may underlie the lack of insight and social isolation that is characteristic of patients with ED.

Aberrant network integrity of the inferior frontal cortex in women with anorexia nervosa

Neuroimaging studies investigating the neural profile of anorexia nervosa (AN) have revealed a predominant imbalance between the reward and inhibition systems of the brain, which are also hallmark characteristics of the disorder. However, little is known whether these changes can also be determined independent of task condition, using resting-state functional magnetic resonance imaging, in currently ill AN patients.

Therefore the aim of our study was to investigate resting-state connectivity in AN patients (n = 12) compared to healthy athlete (n = 12) and non-athlete (n = 14) controls. For this purpose, we used degree centrality to investigate functional connectivity of the whole-brain network and then Granger causality to analyze effective connectivity (EC), to understand directional aspects of potential alterations.

We were able to show that the bilateral inferior frontal gyrus (IFG) is a region of special functional importance within the whole-brain network, in AN patients, revealing reduced functional connectivity compared to both healthy control groups. Furthermore, we found decreased EC from the right IFG to the midcingulum and increased EC from the bilateral orbitofrontal gyrus to the right IFG. For the left IFG, we only observed increased EC from the bilateral insula to the left IFG.

These results suggest that AN patients have reduced connectivity within the cognitive control system of the brain and increased connectivity within regions important for salience processing. Due to its fundamental role in inhibitory behavior, including motor response, altered integrity of the inferior frontal cortex could contribute to hyperactivity in AN.

•

We evaluate resting-state functional (FC) and effective (EC) connectivity.

•

We compare anorexia nervosa (AN) patients with healthy controls.

•

AN patients show reduced FC in the inferior frontal gyrus (IFG).

•

AN patients show reduced EC from the IFG and increased EC to the IFG.

•

Altered FC patterns correlate with physical activity.

The ethics of neuromodulation for anorexia nervosa: a focus on rTMS

OBJECTIVE

Recently there has been emerging clinical and research interest in the application of deep brain stimulation (DBS) and repetitive transcranial magnetic stimulation (rTMS) to the treatment of anorexia nervosa (AN). To our knowledge, few studies have discussed ethical aspects associated with the increased use of neuromodulation in AN, some of which are quite specific to AN, despite the rapid development and dissemination of these new technologies.

METHOD

We provide a brief overview of three published rTMS studies for AN and discuss ethical issues involved in the use of neuromodulation for AN.

RESULTS

In contrast to neurosurgery or DBS, rTMS is a less invasive technique, with less associated risk, and thus has greater potential to become a more widespread augmentation or add-on therapy for AN. New therapeutic procedures are promising, yet they raise ethical questions regarding informed consent and patient selection. Illness-specific issues surrounding authenticity and autonomy are important to consider, ensuring an ethical approach to treatment for patients with AN.

DISCUSSION

We argue that ethical investigations for neuromodulation techniques are timely and important, and discussions should go beyond the immediate goals of patient safety, consent, and risk and benefit, to consider broader ethical concepts such as authenticity and autonomy.

The diagnostic classification of eating disorders: current situation, possible alternatives and future perspectives

The current nosography of eating disorders (ED) has various limitations in terms of validity and accuracy. The changes adopted in the DSM-5 limit some of the current problems, such as excessive prevalence of ED not otherwise specified (EDNOS) and the lack of longitudinal stability, but are unlikely to adequately capture the clinical complexity of ED. Many authors suggest the need for a thorough review of the current nosography to support evidence-based classification. In this paper, we discuss the validity of the current diagnostic categories and their possible reorganization. Furthermore, we review the main empirical models of classification and the diagnostic approach from a personality perspective, with particular attention to research and to the prognostic and therapeutic implications.

Increased BOLD signal in the fusiform gyrus during implicit emotion processing in anorexia nervosa

Background

The behavioural literature in anorexia nervosa (AN) has suggested impairments in psychosocial functioning and studies using facial expression processing tasks (FEPT) have reported poorer recognition and slower identification of emotions.

Methods

Functional magnetic resonance imaging (fMRI) was used alongside a FEPT, depicting neutral, mildly happy and happy faces, to examine the neural correlates of implicit emotion processing in AN. Participants were instructed to specify the gender of the faces. Levels of depression, anxiety, obsessive–compulsive symptoms and eating disorder behaviour were obtained and principal component analysis (PCA) was performed to acquire uncorrelated variables.

Results

fMRI analysis revealed a greater blood-oxygenation level dependent (BOLD) response in AN in the right fusiform gyrus to all facial expressions. This response showed a linear increase with the happiness of the facial expression and was found to be stronger in those not taking medication. PCA analysis revealed a single component indicating a greater level of general clinical symptoms.

Conclusion

Neuroimaging findings would suggest that alterations in implicit emotion processing in AN occur during early perceptual processing of social signals and illustrate greater engagement on the FEPT. The lack of separate components using PCA suggests that the questionnaires used might not be suited as predictive measures.

•

Greater BOLD response in AN in the right fusiform gyrus to all facial expressions.

•

The BOLD response showed a linear increase with the happiness of the expression

•

The BOLD response was stronger in those not taking psychotropic medication

•

These alterations occur during early perceptual processing of social signals

Advances in the neurobiology of eating disorders

PURPOSE OF REVIEW

To systematize new neurobiological findings on the cause and treatment of eating disorders.

RECENT FINDINGS

The conceptual framework of the cause of eating disorders has undergone great changes in the past decades. Recently, the National Institute of Mental Health proposed a new set of criteria for research purposes--the Research Domain Criteria (RDoC). We aim to structure this study as much as possible using these constructs across biological units of analysis, summarizing new findings. Brain imaging techniques have become sophisticated in identifying brain circuits related to illness behaviour and to fundamental traits such as reward and social processing. Genetic studies have moved from candidate gene studies onto genome-wide association studies; however, the field needs to cooperate to collect larger samples in order to benefit from this approach. Hormonal changes as the results of starvation or as underlying factors for behavioural changes still receive attention in both animal and human studies. Advances made in neuropsychology show problems in cognition (set shifting and central coherence) and in other RDoC domains. Some of these findings have been translated into treatment.

SUMMARY

New biological models are being developed which explain causal and maintaining factors. The RDoC construct may be used to systematize these findings.

Is deep brain stimulation a treatment option for anorexia nervosa?

Anorexia nervosa (AN) is a severe psychiatric disorder with high rates of morbidity, comorbidity and mortality, which in a subset of patients (21%) takes on a chronic course. Since an evidence based treatment for AN is scarce, it is crucial to investigate new treatment options, preferably focused on influencing the underlying neurobiological mechanisms of AN. The objective of the present paper was to review the evidence for possible neurobiological correlates of AN, and to hypothesize about potential targets for Deep brain stimulation (DBS) as a treatment for chronic, therapy-refractory AN. One avenue for exploring new treatment options based on the neurobiological correlates of AN, is the search for symptomatologic and neurobiologic parallels between AN and other compulsivity- or reward-related disorders. As in other compulsive disorders, the fronto-striatal circuitry, in particular the insula, the ventral striatum (VS) and the prefrontal, orbitofrontal, temporal, parietal and anterior cingulate cortices, are likely to be implicated in the neuropathogenesis of AN. In this paper we will review the few available cases in which DBS has been performed in patients with AN (either as primary diagnosis or as comorbid condition). Given the overlap in symptomatology and neurocircuitry between reward-related disorders such as obsessive compulsive disorder (OCD) and AN, and the established efficacy of accumbal DBS in OCD, we hypothesize that DBS of the nucleus accumbens (NAc) and other areas associated with reward, e.g. the anterior cingulated cortex (ACC), might be an effective treatment for patients with chronic, treatment refractory AN, providing not only weight restoration, but also significant and sustained improvement in AN core symptoms and associated comorbidities and complications. Possible targets for DBS in AN are the ACC, the ventral anterior limb of the capsula interna (vALIC) and the VS. We suggest conducting larger efficacy studies that also explore the functional effects of DBS in AN.

Visual processing in anorexia nervosa and body dysmorphic disorder: similarities, differences, and future research directions

Anorexia nervosa (AN) and body dysmorphic disorder (BDD) are psychiatric disorders that involve distortion of the experience of one's physical appearance. In AN, individuals believe that they are overweight, perceive their body as "fat," and are preoccupied with maintaining a low body weight. In BDD, individuals are preoccupied with misperceived defects in physical appearance, most often of the face. Distorted visual perception may contribute to these cardinal symptoms, and may be a common underlying phenotype. This review surveys the current literature on visual processing in AN and BDD, addressing lower- to higher-order stages of visual information processing and perception. We focus on peer-reviewed studies of AN and BDD that address ophthalmologic abnormalities, basic neural processing of visual input, integration of visual input with other systems, neuropsychological tests of visual processing, and representations of whole percepts (such as images of faces, bodies, and other objects). The literature suggests a pattern in both groups of over-attention to detail, reduced processing of global features, and a tendency to focus on symptom-specific details in their own images (body parts in AN, facial features in BDD), with cognitive strategy at least partially mediating the abnormalities. Visuospatial abnormalities were also evident when viewing images of others and for non-appearance related stimuli. Unfortunately no study has directly compared AN and BDD, and most studies were not designed to disentangle disease-related emotional responses from lower-order visual processing. We make recommendations for future studies to improve the understanding of visual processing abnormalities in AN and BDD.

A systematic review of the effects of neuromodulation on eating and body weight: evidence from human and animal studies

BACKGROUND

Eating disorders (ED) are chronic and sometimes deadly illnesses. Existing treatments have limited proven efficacy, especially in the case of adults with anorexia nervosa (AN). Emerging neural models of ED provide a rationale for more targeted, brain-directed interventions.

AIMS

This systematic review has examined the effects of neuromodulation techniques on eating behaviours and body weight and assessed their potential for therapeutic use in ED.

METHOD

All articles in PubMed, PsychInfo and Web of Knowledge were considered and screened against a priori inclusion/exclusion criteria. The effects of repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation, vagus nerve stimulation (VNS) and deep brain stimulation (DBS) were examined across studies in ED samples, other psychiatric and neurological disorders, and animal models.

RESULTS

Sixty studies were identified. There is evidence for ED symptom reduction following rTMS and DBS in both AN and bulimia nervosa. Findings from studies of other psychiatric and neurological disorders and from animal studies demonstrate that increases in food intake and body weight can be achieved following DBS and that VNS has potential value as a means of controlling eating and inducing weight loss.

CONCLUSIONS

Neuromodulation tools have potential for reducing ED symptomatology and related behaviours, and for altering food intake and body weight. In response to such findings, and emerging neural models of ED, treatment approaches are highly unlikely to remain 'brainless'. More research is required to evaluate the potential of neuromodulation procedures for improving long-term outcomes in ED.

Impaired inhibitory control in anorexia nervosa elicited by physical activity stimuli

Besides food restriction, hyperactivity is considered a key behavioral trait of anorexia nervosa (AN), playing a major role in the pathogenesis and progression of the disorder. However, the underlying neurophysiology remains poorly understood. We used functional magnetic resonance imaging during two affective go/no-go tasks to probe inhibitory control in response to stimuli depicting physical activity vs inactivity and food vs non-food in AN patients compared with 26 healthy athlete and non-athlete controls. We hypothesized that neural correlates of behavioral inhibition are biased by the emotional information of the stimuli in AN patients, leading to a differential neural inhibitory pattern during the two tasks. Indeed, we found reduced response inhibition for food and non-food images in the putamen, while stimuli depicting physical activity resulted in an exaggerated response of the prefrontal cortex (PFC) and cerebellum in AN patients. However, both AN patients and athletes revealed an increased response in the somatosensory cortex to physical activity stimuli. These results suggest that physical activity stimuli might place an increased demand on the inhibitory control system in AN patients. The resulting hyperactivity of the PFC and cerebellum may lead to altered executive function and motor control, sustaining increased physical activity in AN patients.

The effects of prenatal and postnatal environmental interaction: prenatal environmental adaptation hypothesis

Adverse antenatal maternal environments during pregnancy influence fetal development that consequently increases risks of mental health problems including psychiatric disorders in offspring. Therefore, behavioral and brain alterations caused by adverse prenatal environmental conditions are generally considered as deficits. In this article, we propose a novel hypothesis, along with summarizing a body of literatures supporting it, that fetal neurodevelopmental alterations, particularly synaptic network changes occurring in the prefrontal cortex, associated with adverse prenatal environmental conditions may be adaptation to cope with expected severe postnatal environments, and therefore, psychiatric disorders may be able to be understood as adaptive strategies against severe environmental conditions through evolution. It is hoped that the hypothesis presented in this article stimulates and opens a new venue on research toward understanding of biological mechanisms and therapeutic treatments of psychiatric disorders.

Dissociations between the horizontal and dorsoventral axes in body-size perception

Body size can vary throughout a person's lifetime, inducing plasticity of the internal body representation. Changes in horizontal width accompany those in dorsal-to-ventral thickness. To examine differences in the perception of different body axes, neural correlates of own-body-size perception in the horizontal and dorsoventral directions were compared using functional magnetic resonance imaging. Original and distorted (-30, -10, +10 and +30%) images of the neck-down region of their own body were presented to healthy female participants, who were then asked whether the images were of their own body or not based explicitly on body size. Participants perceived body images distorted by -10% as their own, whereas those distorted by +30% as belonging to others. Horizontal width images yielded slightly more subjective own-body perceptions than dorsoventral thickness images did. Subjective perception of own-body size was associated with bilateral inferior parietal activity. In contrast, other-body judgments showed pre-supplementary motor and superior parietal activity. Expansion in the dorsoventral direction was associated with the left fusiform gyrus and the right inferior parietal lobule, whereas horizontal expansions were associated with activity in the bilateral somatosensory area. These results suggest neural dissociations between the two body axes: dorsoventral images of thickness may require visual processing, whereas bodily sensations are involved in horizontal body-size perception. Somatosensory rather than visual processes can be critical for the assessment of frontal own-body appearance. Visual body thickness and somatosensory body width may be integrated to construct a whole-body representation.

A review of attention biases in women with eating disorders

There is robust evidence that women with eating disorders (EDs) display an attention bias (AB) for disorder-salient stimuli. Emerging data suggest that the presence of these biases may be due, in part, to neurological deficits, such as poor set shifting and weak central coherence. While some have argued that these biases function to predispose and/or act to maintain disordered eating behaviours, evidence supporting this view has rarely been examined. This report summarises and integrates the existing literature on AB in EDs and other related psychiatric disorders to better understand its potential role in the development and maintenance of an ED. The domains reviewed include experimental data using the dot-probe and modified Stroop task and neurobiological findings on AB in women with EDs as well as the role of AB in current theoretical models. We conclude by proposing an integrated model on the role of AB in EDs and discuss treatment approaches aimed at modifying these biases.

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.

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.

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.

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.

Structural magnetic resonance imaging in eating disorders: a systematic review of voxel-based morphometry studies

This systematic review summarises and critically appraises the literature on structural magnetic resonance imaging in people with a current or past eating disorder. Studies using voxel-based morphometry image analysis were included. Ten studies reported on a total of 236 people with a current or past eating disorder and 257 healthy controls. Sample heterogeneity prohibited a meta-analytic approach. The findings do not unequivocally indicate grey or white matter volume abnormalities in people with an eating disorder. Nevertheless, these preliminary data suggest that, compared with healthy controls, people with anorexia nervosa have decreased grey matter in a range of brain regions and that those with bulimia nervosa have increased grey matter volumes in frontal and ventral striatal areas. Research in the recovery phase and longitudinal studies suggest that potential brain tissue abnormalities may recover with clinical improvement. Overall, as the available data are inconclusive, further efforts in this field are warranted.