Structural and functional neural patterns among sub-threshold bulimia nervosa: Abnormalities in dorsolateral prefrontal cortex and orbitofrontal cortex.

BACKGROUND: Disordered eating behaviors are prevalent among youngsters and highly associated with dysfunction in neurocognitive systems. We aimed to identify the potential changes in individuals with bulimia symptoms (sub-BN) to generate insights to understand developmental pathophysiology of bulimia nervosa. METHODS: We investigated group differences in terms of degree centrality (DC) and gray matter volume (GMV) among 145 undergraduates with bulimia symptoms and 140 matched control undergraduates, with the secondary analysis of the whole brain connectivity in these regions of interest showing differences in static functional connectivity (FC). RESULTS: The sub-BN group exhibited abnormalities of the right dorsolateral prefrontal cortex and right orbitofrontal cortex in both GMV and DC, and displayed decreased FC between these regions and the precuneus. We also observed that sub-BN presented with reduced FC between the calcarine and superior temporal gyrus, middle temporal gyrus and inferior parietal gyrus. Additionally, brain-behavioral associations suggest a distinct relationship between these FCs and psychopathological symptoms in sub-BN group. CONCLUSIONS: Our study demonstrated that individuals with bulimia symptoms present with aberrant neural patterns that mainly involved in cognitive control and reward processing, as well as attentional and self-referential processing, which could provide important insights into the pathology of BN.

Adverse childhood experiences, low self-esteem, and salient stimulus response in eating disorders.

BACKGROUND: Adverse childhood experiences (ACEs) are elevated in individuals with eating disorders (EDs), but how the neurobiology of EDs and ACEs interact is unclear. METHODS: Women 18-45 years old with anorexia nervosa (AN, n = 38), bulimia nervosa (BN, n = 32), or healthy controls (n = 60) were assessed for ACEs and ED behaviours and performed a taste-conditioning task during brain imaging. Mediation analyses tested relationships between ACE score, self-esteem, and ED behaviours. RESULTS: ACE scores were elevated in EDs and correlated positively with body mass index (p = 0.001), drive for thinness (p = 0.001), and body dissatisfaction (p = 0.032); low self-esteem mediated the relationship between ACEs and body dissatisfaction, drive for thinness, and bulimia severity. ACE scores correlated negatively (FDR-corrected) with unexpected, salient stimulus receipt in AN (substantia nigra) and BN (anterior cingulate, frontal and insular cortex, ventral striatum, and substantia nigra). When ACE scores were included in the model, unexpected stimulus receipt brain response was elevated in EDs in the anterior cingulate and ventral striatum. CONCLUSIONS: ACEs attenuate unexpected salient stimulus receipt response, which may be a biological marker for altered valence or hedonic tone perception in EDs. Low self-esteem mediates the relationships between ACEs and ED behaviours. Adverse childhood experiences should be assessed in biological studies, and their effects targeted in treatment.

Facial femininity and perceptions of eating disorders: A reverse-correlation study.

Eating disorders are prevalent in college students but college students are not accurate in identifying the presence of eating disorders (ED) especially when race is involved. Much has been researched about diagnostic ability in vignette form, but little outside of this. For example, it is not known how facial features, such as perceived femininity, may affect observers' beliefs about the likelihood of disordered eating depending on race. In the present study, we examined how biases regarding facial appearance and disordered eating may differ depending on the race of face images. Using a technique called reverse correlation, we estimated the image templates associated with perceived likelihood of disordered eating using both White and Black Faces. Specifically, we recruited 28 college students who categorized White and Black faces according to perceived likelihood of an eating disorder diagnosis in the presence of image noise. Subsequently, we asked Amazon Mechanical Turk participants to categorize the resulting race-specific face templates according to perceived ED likelihood and femininity. The templates corresponding to a high likelihood of an ED diagnosis were distinguished from low-likelihood images by this second independent participant sample at above-chance levels. For Black faces, the templates corresponding to a high likelihood of an ED diagnosis were also selected as more feminine than low-likelihood templates at an above-chance level, whereas there was no such effect found for White faces. These results suggest that stereotyped beliefs about both femininity and the likelihood of disordered eating may interact with perceptual processes.

Prefrontal Responses during Proactive and Reactive Inhibition Are Differentially Impacted by Stress in Anorexia and Bulimia Nervosa.

Binge eating is a distressing, transdiagnostic eating disorder symptom associated with impulsivity, particularly in negative mood states. Neuroimaging studies of bulimia nervosa (BN) report reduced activity in frontostriatal regions implicated in self-regulatory control, and an influential theory posits that binge eating results from self-regulation failures under stress. However, there is no direct evidence that psychological stress impairs self-regulation in binge-eating disorders, or that any such self-regulatory deficits generalize to binge eating in underweight individuals (i.e., anorexia nervosa bingeing/purging subtype; AN-BP). We therefore determined the effect of acute stress on inhibitory control in 85 women (BN, 33 women; AN-BP, 22 women; 30 control participants). Participants underwent repeated functional MRI scanning during performance of the Stop-signal anticipation task, a validated measure of proactive (i.e., anticipation of stopping) and reactive (outright stopping) inhibition. Neural and behavioral responses to induced stress and a control task were evaluated on 2 consecutive days. Women with BN had reduced proactive inhibition, while prefrontal responses were increased in both AN-BP and BN. Reactive inhibition was neurally and behaviorally intact in both diagnostic groups. Both AN-BP and BN groups showed distinct stress-induced changes in inferior and superior frontal activity during both proactive and reactive inhibition. However, task performance was unaffected by stress. These results offer novel evidence of reduced proactive inhibition in BN, yet inhibitory control deficits did not generalize to AN-BP. Our findings identify intriguing alterations of stress responses and inhibitory function associated with binge eating, but they counsel against stress-induced failures of inhibitory control as a comprehensive explanation for loss-of-control eating.SIGNIFICANCE STATEMENT Binge eating is a common psychiatric syndrome that feels uncontrollable to the sufferer. Theoretically, it has been related to reduced self-regulation under stress, but there remains no direct evidence for this link in binge-eating disorders. Here, we examined how experimentally induced stress affected response inhibition in control participants and women with anorexia nervosa and bulimia nervosa. Participants underwent repeated brain scanning under stressful and neutral conditions. Although patient groups had intact action cancellation, the slowing of motor responses was impaired in bulimia nervosa, even when the likelihood of having to stop increased. Stress altered brain responses for both forms of inhibition in both groups, yet performance remained unimpaired. These findings counsel against a simple model of stress-induced disinhibition as an adequate explanation for binge eating.

Emotional imagination of negative situations: Functional neuroimaging in anorexia and bulimia.

AIM: The present study aims to extend the knowledge of the neural correlates of emotion processing in first episode subjects affected by anorexia nervosa (AN) or bulimia nervosa (BN). We applied an emotional distress paradigm targeting negative emotions thought to be relevant for interpersonal difficulties and therapeutic resistance mechanisms. METHODS: The current study applied to 44 female participants with newly diagnosed AN or BN and 20 matched controls a neuroimaging paradigm eliciting affective responses. The measurements also included an extensive assessment comprising clinical scales, neuropsychological tests, measures of emotion processing and empathy. RESULTS: AN and BN did not differ from controls in terms of emotional response, emotion matching, self-reported empathy and cognitive performance. However, eating disorder and psychopathological clinical scores, as well as alexithymia levels, were increased in AN and BN. On a neural level, no significant group differences emerged, even when focusing on a region of interest selected a priori: the amygdala. Some interesting findings put in relation the hippocampal activity with the level of Body Dissatisfaction of the participants, the relative importance of the key nodes for the common network in the decoding of different emotions (BN = right amygdala, AN = anterior cingulate area), and the qualitative profile of the deactivations. CONCLUSIONS: Our data do not support the hypothesis that participants with AN or BN display reduced emotional responsiveness. However, peculiar characteristics in emotion processing could be associated to the three different groups. Therefore, relational difficulties in eating disorders, as well as therapeutic resistance, could be not secondary to a simple difficulty in feeling and identifying basic negative emotions in AN and BN participants.

Assessing for Eating Disorders: A Primer for Gastroenterologists.

Eating disorders involve irregularities in eating behavior that may cause gastrointestinal (GI) symptoms. Consequently, many patients with eating disorders seek gastroenterological healthcare at some point in their illness, with many seeking this care even before they seek treatment for and/or diagnosed with their eating disorder. As such, the gastroenterology provider is in a unique position to identify, manage, and facilitate treatment for an eating disorder early in the course of the illness. Although assessing eating disorders is already a difficult task, the identification of eating disorders in patients with GI disease represents an even greater challenge. In particular, common GI symptoms, such as nausea, vomiting, and bloating, may disguise an eating disorder because these symptoms are often viewed as a sufficient impetus for dietary restriction and subsequent weight loss. In addition, the focus on identifying an organic etiology for the GI symptoms can distract providers from considering an eating disorder. During this prolonged diagnostic evaluation, the eating disorder can progress in severity and become more difficult to treat. Unfortunately, a misconception that hinders eating disorder detection is the notion that the rate or method of weight loss is associated with an eating disorder. Regardless of whether weight loss is slow or rapid, purposeful or accidental, eating disorder behaviors and thought patterns may be present. Unidentified eating disorders are not only dangerous in their own right but also can interfere with effective management of GI disease and its symptoms. As such, it is imperative for the GI provider to remain well versed in the identification of these diseases.

Resting energy expenditure in acutely ill and stabilized patients with anorexia nervosa and bulimia nervosa.

OBJECTIVE: Determining resting energy expenditure (REE) may be important in the nutritional assessment of adolescents with eating disorders (EDs). Calculated equations assessing REE, developed according to data from healthy people, may under- or overestimate REE in EDs. We have sought to compare the REE measured in clinical settings to that calculated using equations in actively ill adolescents with anorexia nervosa (AN) and bulimia nervosa (BN), and following stabilization of weight and disordered eating. METHODS: Thirty-five female adolescents with AN and 25 with BN were assessed at admission to inpatient treatment and at discharge. REE was measured using indirect calorimetry (DELTATRAC Metabolic Monitor). Expected REE was calculated using the Harris-Benedict equation. RESULTS: An overestimation of expected versus measured REE was found for both patients with AN and BN, both at admission and discharge. Second, the differences between expected and measured REE were significantly less robust in BN versus AN. Third, REE before renourishing was lower in inpatients with AN versus BN. Fourth, the REE of patients with AN (both measured and expected) increased from admission to discharge, to a greater extent than expected solely from the increase in weight. The difference between admission and discharge expected and measured REE was significant also in patients with BN. DISCUSSION: Our findings suggest that predicted and measured REE are different in both AN and BN, and that both expected and measured REE are not useful in the planning of renourishing programs in patients with AN.

Disturbed Resting-State Whole-Brain Functional Connectivity of Striatal Subregions in Bulimia Nervosa.

BACKGROUND: Disturbed self-regulation, taste reward, as well as somatosensory and visuospatial processes were thought to drive binge eating and purging behaviors that characterize bulimia nervosa. Although studies have implicated a central role of the striatum in these dysfunctions, there have been no direct investigations on striatal functional connectivity in bulimia nervosa from a network perspective. METHODS: We calculated the functional connectivity of striatal subregions based on the resting-state functional Magnetic Resonance Imaging data of 51 bulimia nervosa patients and 53 healthy women. RESULTS: Compared with the healthy women, bulimia nervosa patients showed increased positive functional connectivity in bilateral striatal nuclei and thalamus for nearly all of the striatal subregions, and increased negative functional connectivity in bilateral primary sensorimotor cortex and occipital areas for both ventral striatum and putamen subregions. Only for the putamen subregions, we observed reduced negative functional connectivity in the prefrontal (bilateral superior and middle frontal gyri) and parietal (right inferior parietal lobe and precuneus) areas. Several striatal connectivities with occipital and primary sensorimotor cortex significantly correlated with the severity of bulimia. CONCLUSIONS: The findings indicate bulimia nervosa-related alterations in striatal functional connectivity with the dorsolateral prefrontal cortex supporting self-regulation, the subcortical striatum and thalamus involved in taste reward, as well as the visual occipital and sensorimotor regions mediating body image, which contribute to our understanding of neural circuitry of bulimia nervosa and encourage future therapeutic developments for bulimia nervosa by modulating striatal pathway.

A Systematic Review of Taste Differences Among People With Eating Disorders.

BACKGROUND: Eating disorders are a significant cause of morbidity and mortality. The etiology and maintenance of eating-disorder symptoms are not well understood. Evidence suggests that there may be gustatory alterations in patients with eating disorders. OBJECTIVE: This article systematically reviews research assessing gustatory differences in patients with anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED). METHOD: A systematic review was performed, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, examining taste and eating disorders. We reviewed electronic databases and identified 1,490 peer-reviewed English-language studies. Of these, 49 met inclusion criteria. RESULTS: Studies employed psychophysical measures (n = 27), self-reported questionnaires (n = 5), and neuroimaging techniques (i.e., electroencephalography, functional magnetic resonance imaging; n = 17). Psychophysical studies showed that individuals with BN, in general, had greater preference for sweetness than healthy controls, and those with AN had a greater aversion for fat than controls. In neuroimaging studies, findings suggested that predictable administration of sweet-taste stimuli was associated with reduced activation in taste-reward regions of the brain among individuals with AN (e.g., insula, ventral, and dorsal striatum) but increased activation in BN and BED. DISCUSSION: To our knowledge, this systematic review is the first to synthesize literature on taste differences in AN, BN, and BED. The inconsistency and variability in methods used across studies increased difficulties in comparing studies and disease processes. Further studies with well-defined population parameters are warranted to better understand how taste varies in patients with eating disorders.

Circadian rhythms disruptions and eating disorders: clinical impact and possible psychopathological correlates.

BACKGROUND: A link between abnormalities in circadian rhythms and the development of eating disorders was extensively hypothesized, mainly in consideration of the influence of the circadian clock on eating behavior. The present review is aimed at summarizing the evidence about biological rhythms disruptions in eating disorders, possibly clarifying their impact on the psychopathological profile of such patients. METHODS: Electronic database MEDLINE/PubMed/Index Medicus was systematically searched for original articles examining the prevalence of circadian rhythms disruptions in eating disorders (anorexia nervosa, bulimia nervosa, binge eating disorder). RESULTS: Studies included in the review confirmed the hypothesis of a high prevalence of circadian disruptions in eating disorders. The analyzed research mainly focused on sleep-wake cycle, rest-activity abnormalities and hormonal secretion, whilst literature about other circadian rhythms was scanty. Altered biological rhythms presented higher association with specific psychopathological features, but such relationship was assessed in few studies. CONCLUSIONS: Circadian rhythms disruptions were confirmed to be relevant aspects in the context of eating disorders. Further research is needed in order to clarify the role of biological rhythms in such illnesses, in the attempt to address adjunctive treatment strategies with the possible focus of circadian abnormalities.

Abnormal structural brain network and hemisphere-specific changes in bulimia nervosa.

Bulimia nervosa (BN) is characterized by episodic binge eating and purging behaviors. Disrupted neural processes of self-regulation, taste-rewarding, and body image has been associated with the pathogenesis of BN. However, the structural basis for these behavioral and functional deficits remains largely unknown. We employed diffusion tensor imaging and graph theory approaches (including the nodal properties and network-based statistics (NBS)) to characterize the whole-brain structural network of 48 BN and 44 healthy women. For nodal measures of strength, local efficiency, and betweenness centrality, BN patients displayed abnormal increases in multiple left-lateralized nodes within the mesocorticolimbic reward circuitry (including the orbitofrontal cortex, anterior cingulate, insular, medial temporal, and subcortical areas), lateral temporal-occipital cortex, and precuneus, while reduced global efficiency was observed in the right-lateralized nodes within the dorsolateral prefrontal cortex, mesocorticolimbic circuitry, somatosensory and visuospatial system. Several mesocorticolimbic nodes significantly correlated with BN symptoms. At a network level, we found increased left-lateralized connections primarily within the orbitofrontal cortex and its connections to mesocorticolimbic and lateral temporal-occipital areas, but reduced right-lateralized connections across the inferior frontal gyrus and insula, as well as their connections to the lateral temporal cortex. This study revealed BN-related changes in white-matter connections across the prefrontal control, mesocorticolimbic reward, somatosensory and visuospatial systems. The hemispheric-specific change could be an important aspect of the pathophysiology of BN. By characterizing whole-brain structural network changes of BN, our study provides novel evidence for understanding the behavioral and functional deficits of the disorder.

Associations between physical activity and eating-disorder psychopathology among individuals categorised with binge-eating disorder and bulimia nervosa.

OBJECTIVE: While physical activity (PA) is known to have positive effects on psychological and physical health, little is understood about the association between non-compensatory PA (ie, not compulsive or intended to control weight or shape) and psychopathology among individuals with eating-disorder features. The present study explored associations between non-compensatory PA and psychopathology among adults categorised with bulimia nervosa (BN) and binge-eating disorder (BED). We further explored the association between compensatory PA and psychopathology among those who engaged in that form of "purging." METHOD: Participants were recruited through Mechanical Turk, an online recruitment platform. Individuals categorised with core features of BED (N = 138) and BN (N = 138) completed measures of eating-disorder psychopathology (Eating Disorder Examination - Questionnaire [EDE-Q] and Questionnaire on Eating and Weight Patterns - 5), depression (Patient Health Questionnaire - 2) and PA (both non-compensatory and compensatory, measured using the EDE-Q and Godin Leisure-Time Exercise Questionnaire). RESULTS: Engagement in non-compensatory PA was associated with lower frequency of binge-eating episodes, lower overvaluation of shape/weight and lower dissatisfaction with shape/weight (Ps < .05). Engagement in compensatory PA was related to greater frequency of binge-eating episodes and greater restraint (Ps < .05). DISCUSSION: Non-compensatory PA was associated with lower eating-disorder psychopathology. This suggests that PA is an important, though understudied, health behaviour among persons with features of BED and BN. Future research should examine the potential role of non-compensatory PA in interventions for individuals with core features of these eating disorders.

The influence of oxytocin on risk-taking in the balloon analogue risk task among women with bulimia nervosa and binge eating disorder.

Previous theoretical models of bulimia nervosa (BN) and binge eating disorder (BED) have implicated cross-domain risk-taking behaviour as a significant maintenance factor in both disorders. The present study aimed to test this hypothesis by administering the Balloon Analogue Risk Task (BART) to 25 women with BN or BED and 27 healthy comparison women without a history of an eating disorder. Furthermore, we tested the effect of a divided dose of 64 IU of oxytocin on risk-taking behaviour in the BART. Contrary to our hypothesis, women with BN or BED did not exhibit baseline differences in performance on the BART in the placebo condition (t = 1.42, df = 50, P = 0.161, d = 0.39). Oxytocin did not have a main effect on performance in the BART (F = 0.01, df = 1, P = .907, η2partial  < 0.001); however, there was an interaction, such that participants in the BN/BED participant group, compared to the healthy comparison group, demonstrated safer behaviour on the BART in the oxytocin condition, but not in the placebo condition (F = 4.29, df = 1, P = 0.044, η2partial  = 0.082). These findings cast doubt on the common assumption that individuals with BN and BED exhibit greater risk-taking behaviour in all domains and add to the evidence that oxytocin plays a functional role in modulating behaviours that entail trade-offs between reward approach and risk in humans. We recommend that future dose-response studies investigate the effect of oxytocin on reward approach behaviour further in women with recurrent binge eating behaviour, as well as the clinical significance of this effect.

Reduced mentalizing in patients with bulimia nervosa and features of borderline personality disorder: A case-control study.

BACKGROUND: Mentalizing, the mental capacity to understand oneself and others in terms of mental states, has been found to be reduced in some mental disorders such as Borderline Personality Disorder (BPD). Some studies have suggested that Eating Disorders (EDs) may also be associated with impairments in mentalizing, but studies have not always yielded consistent results. This is the first study to systematically investigate mentalizing impairments in patients with Bulimia Nervosa (BN) compared with controls. In addition, we investigated whether impairments in mentalizing were related to BPD features, rather than BN per se, given the high comorbidity between BPD and BN. METHODS: Patients with BN (n = 53) and healthy controls (HCs; n = 87) completed a battery of measures assessing mentalizing including the Reflective Function Questionnaires (RFQ), the Object Relations Inventory (ORI; Differentiation-Relatedness Scales) and the Reading The Mind in The Eyes Test (RMET). RESULTS: Patients with BN scored significantly lower than HCs on all tests of mentalizing, with moderate to large between-group effect sizes. These differences were partially accounted for by BPD features as assessed with the Zanarini Rating Scale for Borderline Personality Disorder (ZAN-BPD), and partially by bulimic symptoms measured with the Eating Disorder Examination Questionnaire (EDE-Q). CONCLUSIONS: Patients with BN have significantly lower levels of mentalizing as assessed with a broad range of tests compared to HCs. These differences were related to both bulimic symptoms and BPD features. Although further research in larger samples is needed, if replicated, these findings suggest that poor mentalizing may be a significant factor in BN patients and should be addressed in treatment, regardless of the presence of BPD features.

Changes in the sense of agency: Implications for the psychotherapy of bulimia nervosa- A case study.

A sense of agency is a transtheoretical concept that increases our understanding of important processes in psychotherapy. Agency can be described in terms of how strongly the person believes that she can have an impact on her problematic experiences and behaviors. In this case study, a patient's sense of agency in relation to symptoms of bulimia nervosa was assessed during 3 years of psychotherapy. Five distinct phases of agency in relation to eating disorder symptoms were identified: A false sense of agency or no agency at all, a weak sense of agency, a nascent sense of agency, a wavering sense of agency, and a strong sense of agency. A better understanding of patient agency can facilitate adapting approaches and methods best suited for the patient's capacity for change throughout treatment.

Neural Processing of Food and Erotic Cues in Bulimia Nervosa.

OBJECTIVE: Event-related brain potential (ERP) studies have shown that bulimia nervosa (BN) is associated with facilitated processing of disorder-specific stimuli, visible in altered early components during presentation of food cues and bodies varying in size. Less is known about BN and late ERPs, typically less influenced by perceptual features and regarded as more reliable indices of motivational relevance. The purpose of this study was to use the late positive potential (LPP) to investigate the motivational significance of BN-relevant stimuli. METHODS: Highly salient stimuli, such as pictures of personal binge foods and images that are pleasant, neutral, and unpleasant (e.g., human attacks) were presented to 24 women with bulimia and 24 healthy women (19.7 ± 2.1 and 20.5 ± 2.6 years, respectively). Pictures of erotic couples, previously shown to prompt the greatest appetitive reactions in healthy women, were used as pleasant cues. Based on BN aversion to body cues, we hypothesized that the motivational significance of erotic cues could be increased in bulimic women. RESULTS: Consistent with the literature, the LPP was modulated by the salience of the pictures (F(2.8,130.7) = 24.6, p < .001). An additional interaction with diagnostic group (F(2.8,130.7) = 2.8, p = .047) indicated that bulimic women showed a larger LPP than healthy controls during pictures displaying binge foods (p = .037) and erotic couples (p = .031). CONCLUSIONS: The findings provide objective evidence that BN is characterized by dysregulated emotional processing that is not limited to food cues. The implications are discussed within a transdiagnostic perspective on food-related disorders.

Altered thalamo­cortical and occipital­parietal­ temporal­frontal white matter connections in patients with anorexia and bulimia nervosa: a systematic review of diffusion tensor imaging studies

Background: Anorexia nervosa and bulimia nervosa are complex mental disorders, and their etiology is still not fully understood. This paper reviews the literature on diffusion tensor imaging studies in patients with anorexia nervosa and bulimia nervosa to explore the usefulness of white matter microstructural analysis in understanding the pathophysiology of eating disorders. Methods: We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to identify diffusion tensor imaging studies that compared patients with an eating disorder to control groups. We searched relevant databases for studies published from database inception to August 2018, using combinations of select keywords. We categorized white matter tracts according to their 3 main classes: projection (i.e., thalamo­cortical), association (i.e., occipital­parietal­temporal­frontal) and commissural (e.g., corpus callosum). Results: We included 19 papers that investigated a total of 427 participants with current or previous eating disorders and 444 controls. Overall, the studies used different diffusion tensor imaging approaches and showed widespread white matter abnormalities in patients with eating disorders. Despite differences among the studies, patients with anorexia nervosa showed mainly white matter microstructural abnormalities of thalamo­cortical tracts (i.e., corona radiata, thalamic radiations) and occipital­parietal­temporal­frontal tracts (i.e., left superior longitudinal and inferior fronto-occipital fasciculi). It was less clear whether white matter alterations persist after recovery from anorexia nervosa. Available data on bulimia nervosa were partially similar to those for anorexia nervosa. Limitations: Study sample composition and diffusion tensor imaging analysis techniques were heterogeneous. The number of studies on bulimia nervosa was too limited to be conclusive. Conclusion: White matter microstructure appears to be affected in anorexia nervosa, and these alterations may play a role in the pathophysiology of this eating disorder. Although we found white matter alterations in bulimia nervosa that were similar to those in anorexia nervosa, white matter changes in bulimia nervosa remain poorly investigated, and these findings were less conclusive. Further studies with longitudinal designs and multi-approach analyses are needed to better understand the role of white matter changes in eating disorders.

Subcortical Shape Abnormalities in Bulimia Nervosa.

BACKGROUND: Bulimia nervosa (BN) is associated with functional abnormalities in frontostriatal and frontolimbic circuits. Although structural alterations in the frontal portions of these circuits have been observed, this is the first study of subcortical surface morphometry and the largest study of subcortical volume in BN. METHODS: Anatomical magnetic resonance scans were acquired from 62 female participants with full and subthreshold BN (mean age ± SD, 18.7 ± 4.0 years) and 65 group-matched healthy control participants (mean age ± SD, 19.3 ± 5.7 years). General linear models were used to compare groups and assess the significance of group-by-age interactions on the shape and total volume of 15 subcortical structures (p < .05, familywise error corrected). Associations with illness severity and duration were assessed in the BN group. RESULTS: Subcortical volumes did not differ across groups, but vertexwise analyses revealed inward shape deformations on the anterior surface of the pallidum in BN relative to control participants that were associated with binge-eating frequency and illness duration. Inward deformations on the ventrolateral thalamus and dorsal amygdala were more pronounced with advancing age in the BN group, and inward deformations on the caudate, putamen, and amygdala were associated with self-induced vomiting frequency. CONCLUSIONS: Our findings point to localized deformations on the surface of subcortical structures in areas that comprise both reward and cognitive control circuits. These deformations were more pronounced among older BN participants and among those with the most severe symptoms. Such precise localization of alterations in subcortical morphometry may ultimately aid in efforts to identify markers of risk and BN persistence.

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

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

Increased Functional Connectivity Between Ventral Attention and Default Mode Networks in Adolescents With Bulimia Nervosa.

OBJECTIVE: Bulimia nervosa (BN) is characterized by excessive attention to self and specifically to body shape and weight, but the ventral attention (VAN) and default mode (DMN) networks that support attentional and self-referential processes are understudied in BN. This study assessed whether altered functional connectivity within and between these networks contributes to such excessive concerns in adolescents with BN early the course of the disorder. METHOD: Resting-state functional magnetic resonance images were acquired from 33 adolescents with BN and 37 healthy control adolescents (12-21 years) group matched by age and body mass index. Region-of-interest analyses were performed to examine group differences in functional connectivity within and between the VAN and DMN. In addition associations of VAN-DMN connectivity with BN symptoms, body shape/weight concerns, and sustained attention were explored using the Continuous Performance Test (CPT). RESULTS: Compared with control adolescents, those with BN showed significantly increased positive connectivity between the right ventral supramarginal gyrus and all DMN regions and between the right ventrolateral prefrontal cortex and the left lateral parietal cortex. Within-network connectivity did not differ between groups. VAN-DMN connectivity was associated with BN severity and body shape/weight concerns in the BN group. No significant group-by-CPT interactions on VAN-DMN connectivity were detected. CONCLUSION: Increased positive VAN-DMN connectivity in adolescents with BN could reflect abnormal engagement of VAN-mediated attentional processes at rest, perhaps related to their excessive attention to self-referential thoughts about body shape/weight. Future studies should further investigate these circuits as targets for the development of early interventions aimed at decreasing excessive body shape/weight concerns.