Abnormal Social Reward Responses in Anorexia Nervosa: An fMRI Study

Activity-based anorexia in adolescent female rats causes changes in brain mitochondrial dynamics

Anorexia Nervosa (AN) is associated with a high rate of morbidity and mortality as well as a high rate of relapse. The molecular mechanisms underlying the progression of the disorder or the relapses are largely unknown. Patients with AN have been shown to have increased oxidative stress, but its involvement in the development in the disease is unknown. We have previously shown that adolescent female rats undergoing the activity-based anorexia (ABA) paradigm also show signs of oxidative stress. Due to their role in the release of reactive oxygen species (ROS), mitochondria are of high interest in diseases exhibiting oxidative stress. In this study, the impact of ABA on brain mitochondrial dynamics was examined. We found transient changes in the medial prefrontal cortex, hypothalamus, and hippocampus following 25% weight loss and changes in the amygdala at a 10-day weight recovery timepoint. These changes point towards damage in the mitochondria contributing to the oxidative stress.

Longitudinal study in adolescent anorexia nervosa: evaluation of cortico-striatal and default mode network resting-state brain circuits

Anorexia nervosa (AN) typically emerges in adolescence. The cortico-striatal system (CSTS) and the default mode network (DMN) are brain circuits with a crucial development during this period. These circuits underlie cognitive functions that are impaired in AN, such as cognitive flexibility and inhibition, among others. Little is known about their involvement in adolescent AN and how weight and symptom improvement might modulate potential alterations in these circuits. Forty-seven adolescent females (30 AN, 17 healthy control) were clinically/neuropsychologically evaluated and scanned during a 3T-MRI resting-state session on two occasions, before and after a 6-month multidisciplinary treatment of the AN patients. Baseline and baseline-to-follow-up between-group differences in CSTS and DMN resting-state connectivity were evaluated, as well as their association with clinical/neuropsychological variables. Increased connectivity between the left dorsal putamen and the left precuneus was found in AN at baseline. At follow-up, body mass index and clinical symptoms had improved in the AN group. An interaction effect was found in the connectivity between the right dorsal caudate to right mid-anterior insular cortex, with lower baseline AN connectivity that improved at follow-up; this improvement was weakly associated with changes in neuropsychological (Stroop test) performance. These results support the presence of CSTS connectivity alterations in adolescents with AN, which improve with weight and symptom improvement. In addition, at the level of caudate-insula connectivity, they might be associated with inhibitory processing performance. Alterations in CSTS pathways might be involved in AN from the early stages of the disorder.

Social Processing in Eating Disorders: Neuroimaging Paradigms and Research Domain Organizational Constructs

PURPOSE OF REVIEW

Social and environmental factors have been related to both symptom expression of disordered eating in individuals and changes in the prevalence of eating disorders (EDs) in populations. Neural differences in processing social information may contribute to EDs. This review assesses the evidence for aberrant neural responses during social processing in EDs.

RECENT FINDINGS

This review examines how constructs within the social processing domain have been evaluated by neuroimaging paradigms in EDs, including communication, affiliation, and understanding of both oneself and others. Differences related to social processing in EDs include altered processing for self-relevant stimuli, in the context of identity, valence, expectations, and affiliative relationships. Future work is needed to integrate how differences in processing social stimuli relate to alterations in cognitive control and reward as well as specific disordered eating symptoms.

Mapping frontostriatal white matter tracts and their association with reward-related ventral striatum activation in adolescence

The ventral striatum (VS) is implicated in reward processing and motivation. Human and non-human primate studies demonstrate that the VS and prefrontal cortex (PFC), which comprise the frontostriatal circuit, interact to influence motivated behavior. However, there is a lack of research that precisely maps and quantifies VS-PFC white matter tracts. Moreover, no studies have linked frontostriatal white matter to VS activation. Using a multimodal neuroimaging approach with diffusion MRI (dMRI) and functional MRI (fMRI), the present study had two objectives: 1) to chart white matter tracts between the VS and specific PFC structures and 2) assess the association between the degree of VS-PFC white matter tract connectivity and VS activation in 187 adolescents. White matter connectivity was assessed with probabilistic tractography and functional activation was examined with two fMRI tasks (one task with social reward and another task using monetary reward). We found widespread but variable white matter connectivity between the VS and areas of the PFC, with the anterior insula and subgenual cingulate cortex demonstrating the greatest degree of connectivity with the VS. VS-PFC structural connectivity was related to functional activation in the VS though activation depended on the specific PFC region and reward task.

An updated transdiagnostic review of social cognition and eating disorder psychopathology

Existing data suggest that deficits in social cognitive functioning are transdiagnostic phenomena that are observed across various forms of psychopathology. The goal of the present review was to provide an updated systematic review of the literature on social cognitive functioning across eating disorders (EDs), including anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED). Studies that assessed six areas of social cognition were included: theory of mind, social perception, social knowledge, attributional bias, emotion perception, and emotion processing. A systematic search identified 71 studies, the majority of which examined adult women with AN. Research typically focused on alexithymia, theory of mind, empathy, social processing, emotion recognition, or emotion processing. Results suggested some deficits in social cognition in EDs. AN had the most studies with some evidence for deficiencies in social cognition but a fair amount of variability. Research on BN and BED was limited and inconsistent, though there appear to be some deficits in social cognition. Together, the limited coverage across EDs and heterogeneous methodology preclude firm conclusions regarding general or ED-specific deficits, as well as understanding the role of social cognition in ED etiology and maintenance. Therefore, several key questions and future directions are outlined for research moving forward.

Aberrant neural representation of food stimuli in women with acute anorexia nervosa predicts treatment outcome and is improved in weight restored individuals

Anorexia nervosa (AN) has been associated with altered reward processing. We recently reported greater neural response in secondary visual areas when processing visual food stimuli in acutely underweight AN patients (acAN). In order to examine whether the observed alterations are indicative of acute undernutrition or a potential trait marker of AN, we set out to assess neural responses in acAN and in individuals weight-recovered from AN (recAN). FMRI data were collected from a total of 126 female volunteers, 35 acAN, 33 recAN, and 58 age-matched healthy controls (HC) while they viewed streams of food, social and neutral stimuli. A standard general linear model (GLM) was used to interrogate neural responses to the different stimuli in recAN vs. age-matched HC. Moreover, within-subject multivoxel pattern analyses (MVPA) in the two matched samples (acAN/HC and recAN/HC) were used to estimate neural representation of food vs. neutral, and social vs. neutral stimuli. A multiple regression analysis was conducted to test associations between the accuracy of the neural representation and treatment outcome. The GLM revealed no group differences between recAN and HC. The MVPAs showed greater classification accuracy of food stimuli in the posterior fusiform gyrus in acAN but not recAN. Classification accuracy was associated with better treatment outcome. Our findings suggest that the neural representation of food stimuli is altered in secondary visual areas in acAN and normalizes with weight recovery. Possibly this altered representation reflects attentional engagement motivating food intake, which may promote the recovery process.

Tracking temporal response dynamics in the ventral striatum during social feedback in anorexia nervosa: A functional magnetic resonance imaging exploratory study

OBJECTIVE

Research suggests abnormalities in reward-based processes in anorexia nervosa (AN). However, few studies have explored if such alterations might be associated with different temporal activation patterns. This study aims to characterize alterations in time-dependent processes in the ventral striatum (VS) during social feedback in AN using functional magnetic resonance imaging (fMRI).

METHOD

Twenty women with restrictive-subtype AN and 20 age-matched healthy controls (HC) underwent a social judgment experimental fMRI task. Temporal VS hemodynamic responses were extracted in SPM for each participant and each social condition (acceptance/rejection).

RESULTS

Compared with age-matched HC, patients with AN showed a significant time by group interaction of peak VS response throughout the task, with a progressive blunting of peak activation responses, accompanied by a progressive increase in baseline activity levels over time.

DISCUSSION

The results suggest an attenuated response pattern to repetitive social rejection in the VS in patients with AN, together with a difficulty in returning to baseline. The information obtained from this study will guide future, design-specific studies to further explore alterations temporal dynamics.

Differences in the use of emotion regulation strategies between anorexia and bulimia nervosa: A systematic review and meta-analysis

OBJECTIVE

Research has identified abnormal emotion regulation (ER) as an underlying mechanism in the onset and maintenance of eating disorders. Yet, it still remains unclear whether different forms of ER, adaptive and maladaptive strategies, are similar across categories of eating disorders.

METHOD

A systematic review and meta-analysis were carried out to look at ER differences between anorexia nervosa (AN) and bulimia nervosa (BN), two common eating disorder pathologies with different eating patterns.

RESULTS

41 studies were included in the meta-analysis. The results revealed no differences in the use of maladaptive ER strategies between individuals with AN and BN, however patients with AN tend to use less adaptive ER strategies as compared to patients with BN.

CONCLUSIONS

Making less use of adaptive strategies in AN might be due to low body weight and high levels of alexithymia which define AN. In order to improve treatment outcome in individuals suffering from AN, these findings suggest to focus more on improving the use of adaptive ER strategies.

Neural correlates of negative expectancy and impaired social feedback processing in social anxiety

Social anxiety has been associated with abnormalities in cognitive processing in the literature, manifesting as various cognitive biases. To what extent these biases interrupt social interactions remains largely unclear. This study used the Social Judgment Paradigm that could separate the expectation and experience stages of social feedback processing. Event-related potentials (ERPs) in these two stages were recorded to detect the effect of social anxiety that might not be reflected by behavioral data. Participants were divided into two groups according to their social anxiety level. Participants in the high social anxiety (HSA) group were more likely to predict that they would be socially rejected by peers than did their low social anxiety (LSA) counterparts (i.e. the control group). Compared to the ERP data of the LSA group, the HSA group showed: (a) a larger P1 component to social cues (peer faces) prior to social feedback presentation, possibly indicating an attention bias; (b) a difference in feedback-related negativity amplitude between unexpected social acceptance and unexpected social rejection, possibly indicating an expectancy bias; and (c) a diminished sensitivity of the P3 amplitude to social feedback valence (be accepted/be rejected), possibly indicating an experience bias. These results could help understand the cognitive mechanisms that comprise and maintain social anxiety.

Critical incidents in anorexia nervosa: perspectives of those with a lived experience

BACKGROUND

Although social-emotional difficulties are believed play a key role in anorexia nervosa (AN), there is uncertainty regarding what these difficulties might look like. Previous research has largely focused on a "disease model" of social-emotional processing in AN with little attention paid to positive emotions and experiences. Therefore, the aim of the present study was to obtain a fuller picture of critical life events as identified by those with lived AN experience.

METHODS

Thirty-four participants aged 16-48 with current or past AN completed an online survey describing self-defined positive and difficult critical events. Thematic analysis was used to assess patterns in participants narrative responses.

RESULTS

Two major themes were identified in the descriptions of positive critical events: Moments of celebration and Unexpected positive outcomes. These major themes revealed increased external focus and some corrective experiences that challenged the participants pre-existing expectations leading to new positive outcomes. Difficult events clustered into life events that were identified as Eating disorder (ED) related and Non-ED related and included the dimensions of relational conflict and feeling unsupported.

DISCUSSION

The findings suggest that although negative emotionality was identified in the accounts of those with lived experience of AN capacity for "big-picture" thinking with and explicit focus on others was also identified. Moreover, an openness to corrective experiences that worked to challenge negative expectations was evident for some participants. Together these findings have scope as targets for further clinical research and treatment interventions.

Exploring Neural Mechanisms Related to Cognitive Control, Reward, and Affect in Eating Disorders: A Narrative Review of FMRI Studies

Studies using functional magnetic resonance imaging (fMRI) have contributed to our understanding of possible neural abnormalities among individuals with eating disorders. Many of these studies have focused on three domains: 1) cognitive control, 2) reward processing, and 3) affective processing. This review attempts to summarize the recent fMRI findings across these domains among the most well-characterized eating disorders: anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED). Though the literature is a bit murky, a few major themes have emerged. Cognitive control systems are affected among individuals across eating disorder diagnoses, but effects seem least pronounced in AN. Specifically, individuals with all eating disorders appear to show decreased prefrontal activation during cognitive control, but there is less evidence in AN linking decreased prefrontal activation with behavior. There is some evidence that the reinforcing value of food is reduced in AN, but individuals with BN and BED show hyperactivation to rewarding food-related stimuli, suggesting the reinforcing value of food may be enhanced. However, more complex reward processing paradigms show that individuals with BN and BED exhibit hypoactivation to reward anticipation and provide mixed results with regards to reward receipt. There are fewer neuroimaging findings related to affective processing, yet behavioral findings suggest affective processing is important in understanding eating disorders. Though the extant literature is complicated, these studies represent a foundation from which to build and provide insight into potential neurobiological mechanisms that may contribute to the pathophysiology of eating disorders.

The vicious circle of social exclusion and psychopathology: a systematic review of experimental ostracism research in psychiatric disorders

Social exclusion (ostracism) is a major psychosocial factor contributing to the development and persistence of psychiatric disorders and is also related to their social stigma. However, its specific role in different disorders is not evident, and comprehensive social psychology research on ostracism has rather focused on healthy individuals and less on psychiatric patients. Here, we systematically review experimental studies investigating psychological and physiological reactions to ostracism in different responses of psychiatric disorders. Moreover, we propose a theoretical model of the interplay between psychiatric symptoms and ostracism. A systematic MEDLINE and PsycINFO search was conducted including 52 relevant studies in various disorders (some of which evaluated more than one disorder): borderline personality disorder (21 studies); major depressive disorder (11 studies); anxiety (7 studies); autism spectrum disorder (6 studies); schizophrenia (6 studies); substance use disorders (4 studies); and eating disorders (2 studies). Psychological and physiological effects of ostracism were assessed with various experimental paradigms: e.g., virtual real-time interactions (Cyberball), social feedback and imagined scenarios. We critically review the main results of these studies and propose the overall concept of a vicious cycle where psychiatric symptoms increase the chance of being ostracized, and ostracism consolidates or even aggravates psychopathology. However, the specificity and stability of reactions to ostracism, their neurobiological underpinnings, determinants, and moderators (e.g., attachment style, childhood trauma, and rejection sensitivity) remain elusive.

Computer-aided therapeutic diagnosis for anorexia

Background

Anorexia nervosa is a clinical disorder syndrome of the wide spectrum without a fully recognized etiology. The necessary issue in the clinical diagnostic process is to detect the causes of this disease (e.g., my body image, food, family, peers), which the therapist gradually comes to by verifying assumptions using proper methods and tools for diagnostic process. When a person is diagnosed with anorexia, a clinician (a doctor, a therapist or a psychologist) proposes a therapeutic diagnosis and considers the kind of treatment that should be applied. This process is also continued during therapeutic diagnosis. In both cases, it is recommended to apply computer-aided tools designed for testing and confirming the assumptions made by a psychologist. The paper aims to present the computer-aided therapeutic diagnosis method for anorexia. The proposed method consists of 4 stages: free statements of a patient about his/her body image, the general sentiment analysis of statement based on Recurrent Neural Network, assessment of the intensity of five basic emotions: happiness, anger, sadness, fear and disgust (using the Nencki Affective Word List and conversion of words to their basic form), and the assessment of particular areas of difficulties—the sentiment analysis based on the dictionary approach was applied.

Results

The sentiment analysis of a document achieved 72% and 51% of effectiveness, respectively, for RNN and dictionary-based methods. The intensity of sadness (emotion) occurring within the dictionary method is differentiated between control and research group at the level of 10%.

Conclusion

The quick access to the sentiment analysis of a statement on the image of patient’s body, emotions experienced by the patient and particular areas of difficulties of people prone to the anorexia nervosa disorders, may help to establish the diagnosis in a very short time and start an immediate therapy. The proposed automatic method helps to avoid patient’s aversions towards the therapy, which may include avoiding patient–therapist communication, talking about less essential topics, coming late for the sessions. These circumstances can guarantee promising prognosis for recovering.

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

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

The predictive value of the early maladaptive schemas in social situations in anorexia nervosa

BACKGROUND

Patients with anorexia nervosa (AN) show an impairment in the recognition and expression of emotions, as well as an increased sensitivity to being socially excluded, and rigid maladaptive schemas. The Cyberball paradigm is a virtual ball-toss game that can simulate social exclusion and inclusion. Our aim is to evaluate how cognitive schemas can influence the perception and the evaluation of the experiences of social inclusion/exclusion.

METHODS

Thirty-two AN patients and 34 healthy controls completed a psychological evaluation and were randomly assigned to exclusion or overinclusion paradigm of the Cyberball task.

RESULTS

Patients with AN showed a significantly higher level of maladaptive schemas as well as higher sensitivity to being ostracized by peers in comparison with healthy controls. Regression analyses identified specific significant relation between being ostracized and dependence/incompetence, negativity/pessimism, and self-sacrifice.

DISCUSSION

Our findings provide evidence that patients with AN may be ineffective in expressing their mood in exclusive and overinclusive social situations. Specific cognitive/temperamental schemas might play a role in the way people communicate their feelings, and they could be considered targets for psychotherapy interventions to improve social interpretation and emotional recognition/communication.

Neural Processing of Disorder-Related Stimuli in Patients with Anorexia Nervosa: A Narrative Review of Brain Imaging Studies

Abnormalities and alterations in brain function are commonly associated with the etiology and maintenance of anorexia nervosa (AN). Different symptom categories of AN have been correlated with distinct neurobiological patterns in previous studies. The aim of this literature review is to provide a narrative overview of the investigations into neural correlates of disorder-specific stimuli in patients with AN. Although findings vary across studies, a summary of neuroimaging results according to stimulus category allows us to account for methodological differences in experimental paradigms. Based on the available evidence, the following conclusions can be made: (a) the neural processing of visual food cues is characterized by increased top-down control, which enables restrictive eating, (b) increased emotional and reward processing during gustatory stimulation triggers disorder-specific thought patterns, (c) hunger ceases to motivate food foraging but instead reinforces disorder-related behaviors, (d) body image processing is related to increased emotional and hedonic reactions, (e) emotional stimuli provoke increased saliency associated with decreased top-down control and (f) neural hypersensitivity during interoceptive processing reinforces avoidance behavior. Taken together, studies that investigated symptom-specific neural processing have contributed to a better understanding of the underlying mechanisms of AN.

The reduction of astrocytes and brain volume loss in anorexia nervosa-the impact of starvation and refeeding in a rodent model

Anorexia nervosa (AN) is an often chronic, difficult to treat illness that leads to brain volume reductions in gray and white matter. The underlying pathophysiology is poorly understood, despite its potential importance in explaining the neuropsychological deficits and clinical symptoms associated with the illness. We used the activity-based anorexia model (ABA), which includes food reduction and running wheel access in female rats to study brain changes after starvation and refeeding. Longitudinal animal MRI and post-mortem brain sections confirmed a reduction in the mean brain volumes of ABA animals compared to controls. In addition, the mean number of astrocytes was reduced by over 50% in the cerebral cortex and corpus callosum, while the mean number of neurons was unchanged. Furthermore, mean astrocytic GFAP mRNA expression was similarly reduced in the ABA animals, as was the mean cell proliferation rate, whereas the mean apoptosis rate did not increase. After refeeding, the starvation-induced effects were almost completely reversed. The observation of the astrocyte reduction in our AN animal model is an important new finding that could help explain starvation-induced neuropsychological changes in patients with AN. Astrocyte-targeted research and interventions could become a new focus for both AN research and therapy.

A Transdiagnostic Perspective on Social Anhedonia

Humans are highly social beings, yet people with social anhedonia experience reduced interest in or reward from social situations. Social anhedonia is a key facet of schizotypal personality, an important symptom of schizophrenia, and increasingly recognized as an important feature in a range of other psychological disorders. However, to date, there has been little examination of the similarities and differences in social anhedonia across diagnostic borders. Here, our goal was to conduct a selective review of social anhedonia in different psychological and life course contexts, including the psychosis continuum, depressive disorder, posttraumatic stress disorder, eating disorders, and autism spectrum disorders, along with developmental and neurobiological factors. Current evidence suggests that the nature and expression of social anhedonia vary across psychological disorders with some groups showing deficient learning about, enjoyment from, and anticipation of the pleasurable aspects of social interactions, while for others, some of these components appear to remain intact. However, study designs and methodologies are diverse, the roles of developmental and neurobiological factors are not routinely considered, and direct comparisons between diagnostic groups are rare-which prevents a more nuanced understanding of the underlying mechanisms involved. Future studies, parsing the wanting, liking, and learning components of social reward, will help to fill gaps in the current knowledge base. Consistent across disorders is diminished pleasure from social situations, subsequent withdrawal, and poorer social functioning in those who express social anhedonia. Nonetheless, feelings of loneliness often remain, which suggests the need for social connection is not entirely absent. Adolescence is a particularly important period of social and neural development and may provide a valuable window on the developmental origins of social anhedonia. Adaptive social functioning is key to recovery from mental health disorders; therefore, understanding the intricacies of social anhedonia will help to inform treatment and prevention strategies for a range of diagnostic categories.

Interacting neural ensembles in orbitofrontal cortex for social and feeding behaviour

Categorically distinct basic drives (for example, for social versus feeding behaviour^1-3) can exert potent influences on each other; such interactions are likely to have important adaptive consequences (such as appropriate regulation of feeding in the context of social hierarchies) and can become maladaptive (such as in clinical settings involving anorexia). It is known that neural systems regulating natural and adaptive caloric intake, and those regulating social behaviours, involve related circuitry^4-7, but the causal circuit mechanisms of these drive adjudications are not clear. Here we investigate the causal role in behaviour of cellular-resolution experience-specific neuronal populations in the orbitofrontal cortex, a major reward-processing hub that contains diverse activity-specific neuronal populations that respond differentially to various aspects of caloric intake^8-13 and social stimuli^14,15. We coupled genetically encoded activity imaging with the development and application of methods for optogenetic control of multiple individually defined cells, to both optically monitor and manipulate the activity of many orbitofrontal cortex neurons at the single-cell level in real time during rewarding experiences (caloric consumption and social interaction). We identified distinct populations within the orbitofrontal cortex that selectively responded to either caloric rewards or social stimuli, and found that activity of individually specified naturally feeding-responsive neurons was causally linked to increased feeding behaviour; this effect was selective as, by contrast, single-cell resolution activation of naturally social-responsive neurons inhibited feeding, and activation of neurons responsive to neither feeding nor social stimuli did not alter feeding behaviour. These results reveal the presence of potent cellular-level subnetworks within the orbitofrontal cortex that can be precisely engaged to bidirectionally control feeding behaviours subject to, for example, social influences.

Neurobiology of social reward valuation in adults with a history of anorexia nervosa

Objective

Anorexia nervosa (AN) is a disorder characterized by atypical patterns of reward valuation (e.g. positive valuation of hunger). Atypical reward processing may extend into social domains. If so, such findings would be of prognostic significance as impaired social functioning predicts worse outcome. We explore neural circuits implicated in social reward processing in individuals with a history of AN who are weight-restored relative to controls and examine the effects of illness course on the experience of social value.

Method

20 weight-restored individuals with a history of AN (AN-WR) and 24 healthy control (HC) participants were assessed using fMRI tasks that tapped social reward: smiling faces and full human figures that varied in attractiveness and weight.

Results

AN-WR differed from HC in attractiveness ratings by weight (negatively correlated in AN-WR). While there were no significant differences when viewing smiling faces, viewing full figures resulted in decreased activation in regions implicated in reward valuation (the right caudate) for AN-WR and this region was negatively correlated with a sustained course of the disorder. Exploratory whole brain analyses revealed reduced activation in regions associated with social reward, self-referential processing, and cognitive reappraisal (e.g., medial prefrontal cortex, striatum, and nucleus accumbens) with sustained disorder course.

Discussion

The rewarding value of full body images decreases with a sustained disorder course. This may reflect an extension of atypical reward processing documented in AN-WR, perhaps as a function of starvation dampening visceral motivational signals; the deployment of cognitive strategies that lessen the experience of reward; and/or the nature of the stimuli themselves as provocative of eating disorder symptoms (e.g., thin bodies). These findings did not extend to smiling face stimuli. Advances in technology (e.g., virtual avatars, text messaging) may provide novel means to build relationships, including therapeutic relationships, to support improved social connections without threats to symptom provocation.

Subliminal and supraliminal processing of reward-related stimuli in anorexia nervosa

BACKGROUND

Previous studies have highlighted the role of the brain reward and cognitive control systems in the etiology of anorexia nervosa (AN). In an attempt to disentangle the relative contribution of these systems to the disorder, we used functional magnetic resonance imaging (fMRI) to investigate hemodynamic responses to reward-related stimuli presented both subliminally and supraliminally in acutely underweight AN patients and age-matched healthy controls (HC).

METHODS

fMRI data were collected from a total of 35 AN patients and 35 HC, while they passively viewed subliminally and supraliminally presented streams of food, positive social, and neutral stimuli. Activation patterns of the group × stimulation condition × stimulus type interaction were interrogated to investigate potential group differences in processing different stimulus types under the two stimulation conditions. Moreover, changes in functional connectivity were investigated using generalized psychophysiological interaction analysis.

RESULTS

AN patients showed a generally increased response to supraliminally presented stimuli in the inferior frontal junction (IFJ), but no alterations within the reward system. Increased activation during supraliminal stimulation with food stimuli was observed in the AN group in visual regions including superior occipital gyrus and the fusiform gyrus/parahippocampal gyrus. No group difference was found with respect to the subliminal stimulation condition and functional connectivity.

CONCLUSION

Increased IFJ activation in AN during supraliminal stimulation may indicate hyperactive cognitive control, which resonates with clinical presentation of excessive self-control in AN patients. Increased activation to food stimuli in visual regions may be interpreted in light of an attentional food bias in AN.

Altered Medial Frontal Feedback Learning Signals in Anorexia Nervosa

BACKGROUND

In their relentless pursuit of thinness, individuals with anorexia nervosa (AN) engage in maladaptive behaviors (restrictive food choices and overexercising) that may originate in altered decision making and learning.

METHODS

In this functional magnetic resonance imaging study, we employed computational modeling to elucidate the neural correlates of feedback learning and value-based decision making in 36 female patients with AN and 36 age-matched healthy volunteers (12-24 years). Participants performed a decision task that required adaptation to changing reward contingencies. Data were analyzed within a hierarchical Gaussian filter model that captures interindividual variability in learning under uncertainty.

RESULTS

Behaviorally, patients displayed an increased learning rate specifically after punishments. At the neural level, hemodynamic correlates for the learning rate, expected value, and prediction error did not differ between the groups. However, activity in the posterior medial frontal cortex was elevated in AN following punishment.

CONCLUSIONS

Our findings suggest that the neural underpinning of feedback learning is selectively altered for punishment in AN.

The real-life costs of emotion regulation in anorexia nervosa: a combined ecological momentary assessment and fMRI study

Regulation of emotions is necessary for successful attainment of short-term and long-term goals. However, over-regulation may also have its costs. In anorexia nervosa (AN), forgoing food intake despite emaciation and endocrine signals that promote eating is an example of "too much" self-control. Here we investigated whether voluntary emotion regulation in AN patients comes with associated disorder-relevant costs. Thirty-five patients with acute AN and thirty-five age-matched healthy controls (HCs) performed an established emotion regulation paradigm during functional magnetic resonance imaging after an overnight fast. The task required reducing emotions induced by positively valenced pictures via distancing. We calculated a neural regulation score from responses recorded in a reward-related brain region of interest (ventral striatum; VS) by subtracting activation measured on "positive distance" trials from that elicited under the "positive watch" (baseline) condition. Complementing the imaging data, we used ecological momentary assessment (EMA) to probe disorder-related rumination and affect six times/day for 2 weeks following the scanning session. The neural regulation score indicating reduced VS activation during emotion regulation was used as a predictor in hierarchical linear models with EMA measures as outcomes. No group differences in neural activity were found for the main contrasts of the task. However, regulation of VS activity was associated with increased body-related rumination and increased negative affect in AN, but not in HC. In line with this finding, correlational analysis with longitudinal BMI measurements revealed a link between greater VS regulation and poorer treatment outcome after 60 and 90 days. Together, these results identify a neural correlate of altered emotion regulation in AN, which seems to be detrimental to psychological well-being and may interfere with recovery.

Social Difficulties As Risk and Maintaining Factors in Anorexia Nervosa: A Mixed-Method Investigation

Anorexia nervosa (AN) is a serious psychiatric disorder characterized by severe restriction of energy intake and dangerously low body weight. Other domains of functioning are affected, including social functioning. Although difficulties within this domain have started to be acknowledged by the literature, some important gaps remain to be filled. Do social difficulties predate the onset of the illness? What difficulties in particular are relevant for the development and maintenance of the illness? The aim of this study is to combine the use of quantitative and qualitative methods to answer these questions. Ninety participants with lifetime AN (88 women and 2 men) completed an online survey assessing memories of involuntary submissiveness within the family, fear of negative evaluation from others, perceived lack of social competence, feelings of social belonging, eating disorder symptoms, and work and social adjustment. Participants also answered three open questions regarding their experience of social relationships before and after the illness onset. The findings provided support for the hypothesized relationships between the study variables. Involuntary submissiveness and fear of negative evaluation predicted eating disorder symptoms and these associations were partially mediated by perceived lack of social competence. Two-thirds of the sample recalled early social difficulties before illness onset and recognized that these had played a role in the development of the illness. A larger proportion of participants stated that the eating disorder had affected their social relationships in a negative way. This study sheds some light on patients' perspective on the predisposing and maintaining role that social difficulties play in AN and identifies key psychological variables that could be targeted in treatment.

Neural Network Alterations Across Eating Disorders: A Narrative Review of fMRI Studies

BACKGROUND

Functional magnetic resonance imaging (fMRI) has provided insight on how neural abnormalities are related to the symptomatology of the eating disorders (EDs): anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED). More specifically, an increasingly growing number of brain imaging studies has shed light on how functionally connected brain networks contribute not only to disturbed eating behavior, but also to transdiagnostic alterations in body/interoceptive perception, reward processing and executive functioning.

METHODS

This narrative review aims to summarize recent advances in fMRI studies of patients with EDs by highlighting studies investigating network alterations that are shared across EDs.

RESULTS AND CONCLUSION

Findings on reward processing in both AN and BN patients point to the presence of altered sensitivity to salient food stimuli in striatal regions and to the possibility of hypothalamic inputs being overridden by top-down emotional-cognitive control regions. Additionally, innovative new lines of research suggest that increased activations in fronto-striatal circuits are strongly associated with the maintenance of restrictive eating habits in AN patients. Although significantly fewer studies have been carried out in patients with BN and BED, aberrant neural responses to both food cues and anticipated food receipt appear to occur in these populations. These altered responses, coupled with diminished recruitment of prefrontal cognitive control circuitry, are believed to contribute to the binge eating of palatable foods. Results from functional network connectivity studies are diverse, but findings tend to converge on indicating disrupted resting-state connectivity in executive networks, the default-mode network and the salience network across EDs.

Social Rank and Rejection Sensitivity as Mediators of the Relationship between Insecure Attachment and Disordered Eating

AIM

The current study assessed a new interpersonal model for eating disorders (EDs), in which interpersonal rejection sensitivity (RS), appearance-based RS and social rank were hypothesised to mediate the relationship between insecure attachment and disordered eating.

METHOD

The sample comprised a clinical ED group (N = 122) and a control group (N = 622). Participants were asked to complete a number of self-report measures related to the variables of interest.

RESULTS

Invariance testing indicated that the model was structurally non-invariant (different across groups). For the ED group, appearance-based RS and social rank were significant mediators of the relationship between insecure attachment and disordered eating. For the controls, the relationship between insecure attachment and disordered eating was mediated through multiple pathways involving interpersonal RS, appearance-based RS and social rank.

CONCLUSION

These findings may inform existing therapies such as interpersonal psychotherapy for EDs, by emphasising the role of sensitivity to rejection in the development and maintenance of disordered eating. Copyright © 2017 John Wiley & Sons, Ltd and Eating Disorders Association.

Neural correlates of social exclusion across ages: A coordinate-based meta-analysis of functional MRI studies

Given the recent surge in functional neuroimaging studies on social exclusion, the current study employed activation likelihood estimation (ALE) based meta-analyses to identify brain regions that have consistently been implicated across different experimental paradigms used to investigate exclusion. We also examined the neural correlates underlying Cyberball, the most commonly used paradigm to study exclusion, as well as differences in exclusion-related activation between developing (7-18 years of age, from pre-adolescence up to late adolescence) and emerging adult (broadly defined as undergraduates, including late adolescence and young adulthood) samples. Results revealed involvement of the bilateral medial prefrontal and posterior cingulate cortices, right precuneus and left ventrolateral prefrontal cortex across the different paradigms used to examine social exclusion; similar activation patterns were identified when restricting the analysis to Cyberball studies. Investigations into age-related effects revealed that ventrolateral prefrontal activations identified in the full sample were driven by (i.e. present in) developmental samples, while medial prefrontal activations were driven by emerging adult samples. In addition, the right ventral striatum was implicated in exclusion, but only in developmental samples. Subtraction analysis revealed significantly greater activation likelihood in striatal and ventrolateral prefrontal clusters in the developmental samples as compared to emerging adults, though the opposite contrast failed to identify any significant regions. Findings integrate the knowledge accrued from functional neuroimaging studies on social exclusion to date, highlighting involvement of lateral prefrontal regions implicated in regulation and midline structures involved in social cognitive and self-evaluative processes across experimental paradigms and ages, as well as limbic structures in developing samples specifically.

Hemispheric lateralization of resting-state functional connectivity of the ventral striatum: an exploratory study

Resting-state functional connectivity (rsFC) is widely used to examine cerebral functional organization. The ventral striatum (VS) is critical to motivated behavior, with extant studies suggesting functional hemispheric asymmetry. The current work investigated differences in rsFC between the left (L) and right (R) VS and explored gender differences in the extent of functional lateralization. In 106 adults, we computed a laterality index (fcLI) to query whether a target region shows greater or less connectivity to the L vs R VS. A total of 45 target regions with hemispheric masks were examined from the Automated Anatomic Labeling atlas. One-sample t test was performed to explore significant laterality in the whole sample and in men and women separately. Two-sample t test was performed to examine gender differences in fcLI. At a corrected threshold (p < 0.05/45 = 0.0011), the dorsomedial prefrontal cortex (dmPFC) and posterior cingulate cortex (pCC) showed L lateralization and the intraparietal sulcus (IPS) and supramarginal gyrus (SMG) showed R lateralization in VS connectivity. Except for the pCC, these findings were replicated in a different data set (n = 97) from the Human Connectome Project. Furthermore, the fcLI of VS-pCC was negatively correlated with a novelty seeking trait in women but not in men. Together, the findings may suggest a more important role of the L VS in linking saliency response to self control and other internally directed processes. Right lateralization of VS connectivity to the SMG and IPS may support attention and action directed to external behavioral contingencies.

Attachment Insecurity Predicts Punishment Sensitivity in Anorexia Nervosa

Individuals with anorexia nervosa (AN) experience insecure attachment. We investigated whether insecure attachment is associated with punishment and reward sensitivity in women with AN. Women with AN (n = 24) and comparison women (n = 26) (CW) completed The Eating Disorder Examination Questionnaire, Depression Anxiety Stress Scale, The Attachment Style Questionnaire, and Sensitivity to Punishment/Sensitivity to Reward Questionnaire. Participants with AN returned higher ratings for insecure attachment (anxious and avoidant) experiences and greater sensitivity to punishment (p = 0.001) than CW. In AN, sensitivity to punishment was positively correlated with anxious attachment and negative emotionality but not eating disorder symptoms. Regression analysis revealed that anxious attachment independently predicted punishment sensitivity in AN. Anxious attachment experiences are related to punishment sensitivity in AN, independent of negative emotionality and eating disorder symptoms. Results support ongoing investigation of the contribution of attachment experiences in treatment and recovery.

Alterations in emotion generation and regulation neurocircuitry in depression and eating disorders: A comparative review of structural and functional neuroimaging studies

Major depression and eating disorders (EDs) are highly co-morbid and may share liability. Impaired emotion regulation may represent a common etiological or maintaining mechanism. Research has demonstrated that depressed individuals and individuals with EDs exhibit impaired emotion regulation, with these impairments being associated with changes in brain structure and function. The goal of this review was to evaluate findings from neuroimaging studies of depression and EDs to determine whether there are overlapping alterations in the brain regions known to be involved in emotion regulation, evidence of which would aid in the diagnosis and treatment of these conditions. Our review of the literature suggests that depression and EDs exhibit common structural and functional alterations in brain regions involved in emotion regulation, including the amygdala, ventral striatum and nucleus accumbens, anterior cingulate cortex, insula, and dorsolateral prefrontal cortex. We present preliminary support for a shared etiological mechanism. Future studies should consider manipulating emotion regulation in a sample of individuals with depression and EDs to better characterize abnormalities in these brain circuits.

Facial expression to emotional stimuli in non-psychotic disorders: A systematic review and meta-analysis

Facial expression of emotion is crucial to social interaction and emotion regulation; therefore, altered facial expressivity can be a contributing factor in social isolation, difficulties with emotion regulation and a target for therapy. This article provides a systematic review and meta-analysis of the literature on automatic emotional facial expression in people with non-psychotic disorders compared to healthy comparison groups. Studies in the review used an emotionally salient visual induction method, and reported on automatic facial expression in response to congruent stimuli. A total of 39 studies show alterations in emotional facial expression across all included disorders, except anxiety disorders. In depression, decreases in facial expression are mainly evident for positive affect. In eating disorders, a meta-analysis showed decreased facial expressivity in response to positive and negative stimuli. Studies in autism partially support generally decreased facial expressivity in this group. The data included in this review point towards decreased facial emotional expressivity in individuals with different non-psychotic disorders. This is the first review to synthesise facial expression studies across clinical disorders.

Targeting Neural Endophenotypes of Eating Disorders with Non-invasive Brain Stimulation

The term "eating disorders" (ED) encompasses a wide variety of disordered eating and compensatory behaviors, and so the term is associated with considerable clinical and phenotypic heterogeneity. This heterogeneity makes optimizing treatment techniques difficult. One class of treatments is non-invasive brain stimulation (NIBS). NIBS, including repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), are accessible forms of neuromodulation that alter the cortical excitability of a target brain region. It is crucial for NIBS to be successful that the target is well selected for the patient population in question. Targets may best be selected by stepping back from conventional DSM-5 diagnostic criteria to identify neural substrates of more basic phenotypes, including behavior related to rewards and punishment, cognitive control, and social processes. These phenotypic dimensions have been recently laid out by the Research Domain Criteria (RDoC) initiative. Consequently, this review is intended to identify potential dimensions as outlined by the RDoC and the underlying behavioral and neurobiological targets associated with ED. This review will also identify candidate targets for NIBS based on these dimensions and review the available literature on rTMS and tDCS in ED. This review systematically reviews abnormal neural circuitry in ED within the RDoC framework, and also systematically reviews the available literature investigating NIBS as a treatment for ED.

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.