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

A randomized, controlled pilot study of positive affect treatment adapted for anorexia nervosa

OBJECTIVE

Novel treatments for adults with anorexia nervosa (AN) are sorely needed. Although psychological interventions have been developed for AN, none have been identified as superior to one another or nonspecific treatments. Common comorbidities (e.g., mood and anxiety disorders) are rarely targeted in AN treatments, possibly impairing long-term clinical improvement. AN is associated with reward processing dysfunctions paralleling those identified in affective disorders; however, few treatments directly target these processes.

METHOD

We adapted Positive Affect Treatment, a neuroscience-informed behavioral treatment developed for affective disorders, to the treatment of AN (PAT-AN). Adults with AN (N = 20) were randomized to 20 weeks of PAT-AN or waitlist to investigate the feasibility, acceptability, preliminary efficacy, and target engagement (on reward mechanisms) of PAT-AN.

RESULTS

PAT-AN demonstrated strong retention (100%) and acceptability ratings (M = 5.67-5.95 on a 7-point scale). BMI (p = .006) and eating disorder symptoms (p < .001) improved over PAT-AN sessions. The PAT-AN group showed medium to large pre-to-post-treatment improvements in BMI, eating disorder symptoms and impairment, depressive and anxiety symptoms, and some reward indices (ds = .56-.87); changes were largely sustained at 3-month follow-up. Waitlist showed negligible changes (ds < .20) on nearly all measures.

DISCUSSION

PAT-AN holds promise as an innovative treatment with capability to simultaneously improve eating disorder symptoms, affective symptoms, and underlying reward mechanisms. Findings should be interpreted cautiously due to small sample size and permitted concurrent enrollment in other treatments. Future, larger-scale research is warranted to establish the efficacy of PAT-AN.

PUBLIC SIGNIFICANCE

This study provided a preliminary evaluation of Positive Affect Treatment for anorexia nervosa (PAT-AN), a novel, neuroscience-informed treatment aimed at increasing rewarding life experiences outside of one's eating disorder. Initial results suggest that PAT-AN is considered acceptable and may alleviate eating disorder, depressive, and anxiety symptoms. Therefore, this study presents promising data on a treatment that may hold potential for improving the lives of individuals with this disorder.

Reward responsivity and habit formation in the co-occurrence of restrictive eating and nonsuicidal self-injury

Dysfunctions in reward and/or habit formation have been proposed as factors contributing individually to the maintenance of restrictive eating and nonsuicidal self-injury (NSSI). However, despite the high comorbidity between these behaviors, the associations between reward and habit formation in their co-occurrence remains unclear. This study examined self-reported reward responsivity and habit strength among individuals with co-occurring restrictive eating and NSSI (Comorbid group; n = 108) and those with one behavior only (One-behavior group; n = 113). Hierarchical logistic regression analyses assessed the association between reward and habit features and the co-occurrence of restrictive eating and NSSI, accounting for the effects of impulsivity (a characteristic commonly considered to underlie co-occurring disordered eating and NSSI). Partial correlations examined the relationships between these features and the severity of eating disorder and NSSI symptoms, also controlling for impulsivity. Lower reward responsivity was associated with the co-occurrence of restrictive eating and NSSI, even after accounting for impulsivity (p = 0.017). In exploratory analyses, this relationship was no longer significant after accounting for self-reported depression. No significant associations were found regarding habit formation and restrictive eating and NSSI co-occurrence. Lower reward responsivity was linked to increased NSSI frequency and versatility in both groups and associated with severity of eating pathology in the Comorbid group (ps < 0.05). Our findings suggest that blunted reward responsivity may relate to the co-occurrence of restrictive eating, NSSI, and depressive symptoms, as well as the severity of restrictive eating and NSSI. Reward disturbances may serve as a crucial target in the treatment of multiple self-destructive behaviors.

Change in motivational bias during treatment predicts outcome in anorexia nervosa

OBJECTIVE

Reward and punishment sensitivity are known to be altered in anorexia nervosa (AN). Most research has examined these constructs separately although motivated behavior is influenced by considering both the potential for reward and risk of punishment. The present study sought to compare the relative balance of reward and punishment sensitivity in AN versus healthy controls (HCs) and examine whether motivational bias is associated with AN symptoms and treatment outcomes.

METHODS

Adolescents and adults with AN (n = 262) in a partial hospitalization program completed the Eating Disorders Examination Questionnaire (EDE-Q), Behavioral Inhibition System/Behavioral Activation System (BIS/BAS) scales, and Sensitivity to Punishment/Sensitivity to Reward Questionnaire (SPSRQ) at admission and discharge. HCs (HC; n = 90) completed the BIS/BAS and SPSRQ. Motivational Bias Scores were calculated to reflect the dominance of reward versus punishment sensitivity.

RESULTS

Individuals with AN demonstrated significantly greater bias toward punishment sensitivity than HC. In AN, a bias toward punishment was associated with higher EDE-Q Global score at admission. Change in motivational bias during treatment predicted EDE-Q Global scores, but not BMI, at discharge, with greater increases in reward sensitivity or greater decreases in punishment sensitivity during treatment predicting lower eating pathology. Similar findings were observed using the BIS/BAS and SPSRQ.

DISCUSSION

Change in motivational bias during treatment is associated with improved outcomes in AN. However, it appears that much of the change in motivational bias can be attributed to changes in punishment sensitivity, rather than reward sensitivity. Future research should examine the mechanisms underlying punishment sensitivity decreases during treatment.

PUBLIC SIGNIFICANCE

Sensitivity to reward and punishment may be important treatment targets for individuals with anorexia nervosa (AN). To date, most research has considered reward and punishment sensitivity separately, rather than examining their relationship to each other. We found that the balance of reward and punishment sensitivity (i.e., motivational bias) differs between healthy controls and those with AN and that this bias is associated with eating disorder symptoms and treatment outcome.

Neurocognitive reward processes measured via event-related potentials are associated with binge-eating disorder diagnosis and ecologically-assessed behavior

Altered reward processing has been implicated in the onset and maintenance of binge-eating disorder (BED). However, it is unclear which precise neurocognitive reward processes may contribute to BED. In the present study, 40 individuals with BED and 40 age-, sex-, and BMI-matched controls completed a reward (incentive delay) task while their neural activity was recorded using electroencephalography (EEG). Individuals with BED also completed a 10-day ecological momentary assessment (EMA) protocol assessing binge-eating behavior in the natural environment. Event-related potential (ERP) analysis of the EEG indicated that individuals with BED had stronger anticipatory (CNV) and outcome-related (RewP) neural reward activity to food and monetary rewards, compared to controls. However, within the BED group, greater frequency of binge eating during the EMA protocol was associated with stronger anticipatory (CNV) but weaker outcome-related (RewP) neural reward activity. These associations within the BED group were unique to food, and not monetary, rewards. Although preliminary, these results suggest that both anticipatory ("wanting") and outcome ("liking") reward processes may be generally amplified in BED. However, they also suggest that among individuals with BED, disorder severity may be associated with increased anticipatory reward processes ("wanting"), but relatively decreased reward-outcome processing ("liking"), of food rewards specifically.

Dynamic Amygdala Nuclei Alterations in Relation to Weight Status in Anorexia Nervosa Are Mediated by Leptin

OBJECTIVE

The amygdaloid complex is a subcortical limbic group of distinct nuclei. In a previous patient-control study, differential amygdala nuclei alterations were found in acute anorexia nervosa (AN); rostral-medial nuclei involved in fear and reward processing were substantially reduced in volume and associated with hypoleptinemia, a key neuroendocrine characteristic of AN. Here, longitudinal amygdala nuclei alterations in AN were investigated in relation to weight status and their associations with leptin levels.

METHOD

T1-weighted structural magnetic resonance imaging scans were longitudinally processed with FreeSurfer. Amygdala nuclei volumes in young female patients with acute AN before and after short-term weight restoration (n = 110, >14% body mass index increase over 3 months) and female participants with a history of AN (n = 79, long-term [mean 5 years] weight recovered) were compared with female healthy control participants (n = 271) using linear mixed effects models.

RESULTS

Rostral-medially clustered amygdala nuclei volumes, accessory basal, cortical, medial nuclei, and corticoamygdaloid transition, increased during short-term weight restoration (Cohen's d range 0.18-0.30). However, volumetric normalization across nuclei was heterogeneous. Right cortical, medial nuclei, bilateral corticoamygdaloid transitions, and anterior amygdaloid areas were only partially normalized following short-term weight restoration. Right anterior amygdaloid area remained reduced after long-term weight recovery compared with control participants (d = 0.36). Leptin increase, accompanying short-term weight restoration, mediated the effect of weight gain on volumetric increase in left corticoamygdaloid transition and bilateral medial nuclei.

CONCLUSION

Rostral-medially clustered amygdala nuclei show pronounced volumetric increase but incomplete normalization in AN during and after short-term weight restoration. Leptin increase may be relevant for the recovery of specific amygdala nuclei in addition to nutritional rehabilitation, indicating links between amygdala substructure and leptin dynamics of potential pathophysiological and clinical relevance in AN.

PLAIN LANGUAGE SUMMARY

The amygdala plays a critical role in processing fearful and rewarding stimuli, and alterations in the amygdala are associated with anorexia nervosa. In this study, the authors measured amygdala nuclei volumes in female patients with acute anorexia nervosa undergoing weight-restoration treatment (n = 110), long-term weight-recovered individuals with anorexia (n = 79), and healthy control participants (n = 271). Structural magnetic resonance imaging revealed that volumes of specific nuclei, clustered in the rostral-medial amygdala, were substantially reduced in acute anorexia nervosa and only partially normalized following weight restoration treatment. Residual reductions in volume persisted even after long-term weight-recovery, compared to healthy control participants. Short-term weight restoration was associated with increases in the neurohormone leptin, and increasing leptin levels were found to mediate the positive impact of weight gain on increased amygdala volume over the treatment course.

DIVERSITY & INCLUSION STATEMENT

We worked to ensure race, ethnic, and/or other types of diversity in the recruitment of human participants. We worked to ensure that the study questionnaires were prepared in an inclusive way. One or more of the authors of this paper received support from a program designed to increase minority representation in science. We actively worked to promote sex and gender balance in our author group. We actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our author group. While citing references scientifically relevant for this work, we also actively worked to promote sex and gender balance in our reference list. While citing references scientifically relevant for this work, we also actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our reference list. The author list of this paper includes contributors from the location and/or community where the research was conducted who participated in the data collection, design, analysis, and/or interpretation of the work.

Mouse-cursor trajectories reveal reduced contextual influence on decision conflict during delay discounting in anorexia nervosa

OBJECTIVE

The capacity of individuals with anorexia nervosa (AN) to forgo immediate food rewards in their long-term pursuit of thinness is thought to reflect elevated self-control and/or abnormal reward sensitivity. Prior research attempted to capture an increased tendency to delay gratification in AN using delay-discounting tasks that assess how rapidly the subjective value of rewards decreases as a function of time until receipt. However, significant effects were mostly subtle or absent. Here, we tested whether the process leading to such decisions might be altered in AN.

METHOD

We recorded mouse-cursor movement trajectories leading to the final choice in a computerized delay-discounting task (238 trials) in 55 acutely underweight females with AN and pairwise age-matched female healthy controls (HC). We tested for group differences in deviations from a direct choice path, a measure of conflict strength in decision making, and whether group moderated the effect of several predictors of conflict strength (e.g., choice difficulty, consistency). We also explored reaction times and changes in trajectory directions (X-flips).

RESULTS

No group differences in delay-discounting parameters or movement trajectories were detected. However, the effect of the aforementioned predictors on deviations (and to a lesser extent reaction times) was reduced in AN.

DISCUSSION

These findings suggest that while delay discounting and conflict strength in decision making are generally unaltered in AN, conflict strength was more stable across different decisions in the disorder. This might enable individuals with AN to pursue (maladaptive) long-term body-weight goals, because particularly conflicting choices may not be experienced as such.

PUBLIC SIGNIFICANCE

The deviations from a direct path of mouse-cursor movements during a computerized delay-discounting task varied less in people with anorexia nervosa. Assuming such deviations measure decision conflict, we speculate that this increased stability might help people with anorexia nervosa achieve their long-term weight goals, as for them the struggle with the decision to eat high-calorie meals when hungry will be milder, so they would be more likely to skip them.

Differential alterations of amygdala nuclei volumes in acutely ill patients with anorexia nervosa and their associations with leptin levels

BACKGROUND

The amygdala is a subcortical limbic structure consisting of histologically and functionally distinct subregions. New automated structural magnetic resonance imaging (MRI) segmentation tools facilitate the in vivo study of individual amygdala nuclei in clinical populations such as patients with anorexia nervosa (AN) who show symptoms indicative of limbic dysregulation. This study is the first to investigate amygdala nuclei volumes in AN, their relationships with leptin, a key indicator of AN-related neuroendocrine alterations, and further clinical measures.

METHODS

T1-weighted MRI scans were subsegmented and multi-stage quality controlled using FreeSurfer. Left/right hemispheric amygdala nuclei volumes were cross-sectionally compared between females with AN (n = 168, 12-29 years) and age-matched healthy females (n = 168) applying general linear models. Associations with plasma leptin, body mass index (BMI), illness duration, and psychiatric symptoms were analyzed via robust linear regression.

RESULTS

Globally, most amygdala nuclei volumes in both hemispheres were reduced in AN v. healthy control participants. Importantly, four specific nuclei (accessory basal, cortical, medial nuclei, corticoamygdaloid transition in the rostral-medial amygdala) showed greater volumetric reduction even relative to reductions of whole amygdala and total subcortical gray matter volumes, whereas basal, lateral, and paralaminar nuclei were less reduced. All rostral-medially clustered nuclei were positively associated with leptin in AN independent of BMI. Amygdala nuclei volumes were not associated with illness duration or psychiatric symptom severity in AN.

CONCLUSIONS

In AN, amygdala nuclei are altered to different degrees. Severe volume loss in rostral-medially clustered nuclei, collectively involved in olfactory/food-related reward processing, may represent a structural correlate of AN-related symptoms. Hypoleptinemia might be linked to rostral-medial amygdala alterations.

Integrating aspects of affect, reward, and cognition to develop more comprehensive models of binge-eating pathology

Reward-related processes are an increasing focus of eating disorders research. Although evidence suggests that numerous distinct reward processes may contribute to eating pathology (e.g., reward learning and delay discounting), existing etiological models of reward dysfunction tend to focus on only a limited number of reward processes, and frequently lack specificity when identifying the individual reward processes hypothesized to contribute to dysregulated eating behavior. Moreover, existing theories have been limited in their integration of reward-related processes with other demonstrated risk and maintenance factors for eating disorders (e.g., affect and cognition), potentially contributing to underdeveloped models of eating pathology. In this article, we highlight five distinct reward processes with theorized or demonstrated relevance to eating disorders involving binge-eating, followed by a review of two well-established risk/maintenance factors for binge-eating pathology. We then introduce two novel models of binge eating onset and maintenance that integrate these factors (i.e., the Affect, Reward, Cognition models), and discuss methods for testing each of the models in future research. Ultimately, we hope that the proposed models provide a springboard for the continued evolution of more precise and comprehensive theories of reward dysfunction in the eating disorders, as well as the development of novel intervention approaches. PUBLIC SIGNIFICANCE STATEMENT: Eating disorders are associated with abnormalities in multiple domains of reward functioning. However, models of reward dysfunction within the eating disorders have not been well-integrated with prominent models of affect and cognition. This article presents two novel models of onset and maintenance for binge-eating pathology, which attempt to integrate observed reward abnormalities with other affective and cognitive processes implicated in binge-type eating disorders.

Can you learn to starve yourself? Inducing food avoidance in the laboratory

The restriction of energy intake is a central and persistent symptom of anorexia nervosa. Recent models of the disorder suggest that food restrictions are learned avoidance behaviours, which are acquired and maintained by classical and operant conditioning. The present study aims to test this learning model of food restriction. It investigates whether introducing negative consequences for the intake of tasty high-calorie food and introducing positive consequences for its avoidance can create food avoidance, increase fear of food, and decrease eating desires in healthy individuals. 104 women were randomly assigned to an experimental or control condition and completed an appetitive conditioning and avoidance learning task. While the experimental condition received money after avoiding the tasty high-calorie food item and heard an aversive sound after not avoiding food intake, the control condition never received these consequences. In the extinction phase, reward and punishment discontinued for both conditions. We measured avoidance frequency, mouse movements, fear, eating desires and stimulus liking. Participants in the experimental condition avoided the food more often than controls and showed increased fear, reduced eating desires and less liking for cues associated with food intake. These results support the notion that food avoidance behaviours, reduced eating desires and fear of food can be learned via classical and operant conditioning. Conditioning paradigms might be a useful tool to study the development and maintenance of food restriction in anorexia nervosa.

The effects of acute tryptophan depletion on instrumental reward learning in anorexia nervosa - an fMRI study

BACKGROUND

The serotonin (5-HT) hypothesis of anorexia nervosa (AN) posits that individuals predisposed toward or recovered from AN (recAN) have a central nervous hyperserotonergic state and therefore restrict food intake as a means to reduce 5-HT availability (via diminished tryptophan-derived precursor supply) and alleviate associated negative mood states. Importantly, the 5-HT system has also been generally implicated in reward processing, which has also been shown to be altered in AN.

METHODS

In this double-blind crossover study, 22 individuals recAN and 25 healthy control participants (HC) underwent functional magnetic resonance imaging (fMRI) while performing an established instrumental reward learning paradigm during acute tryptophan depletion (ATD; a dietary intervention that lowers central nervous 5-HT availability) as well as a sham depletion.

RESULTS

On a behavioral level, the main effects of reward and ATD were evident, but no group differences were found. fMRI analyses revealed a group × ATD × reward level interaction in the ventral anterior insula during reward anticipation as well as in the medial orbitofrontal cortex during reward consumption.

DISCUSSION

The precise pattern of results is suggestive of a 'normalization' of reward-related neural responses during ATD in recAN compared to HC. Our results lend further evidence to the 5-HT hypothesis of AN. Decreasing central nervous 5-HT synthesis and availability during ATD and possibly also by dieting may be a means to normalize 5-HT availability and associated brain processes.

Learned industriousness as a translational mechanism in anorexia nervosa

It remains unexplained why some behaviours persist despite being non-hedonic and ostensibly aversive. This phenomenon is especially baffling when such behaviours are taken to excess in the form of psychopathology. Anorexia nervosa is one psychiatric disorder in which effortful behaviours that most people find unpleasant (suchas restrictive eating) are persistently performed. We propose thatthe social psychology theory of learned industriousness providesa novel mechanistic account for such phenomena. This theoryposits that high-effort behaviour can be conditioned to acquire secondary reinforcing properties through repeated pairing with reward. Accordingly, effort sensations become less aversive andmore appetitive, increasing willingness to engage in effortful behaviour. In this Perspective, we review pre-clinical behaviouraland biological data that support learned industriousness, contrast learned industriousness with other models of non-hedonic persistence (such as habit learning), highlight evidence that supports learned industriousness in individuals with anorexia nervosa and consider implications of the model, including translation to other psychiatric presentations.

The potential application of event-related potentials to enhance research on reward processes in eating disorders

OBJECTIVE

Reward-related processes have been posited as key mechanisms underlying the onset and persistence of eating disorders, prompting a growing body of research in this area. Existing studies have primarily utilized self-report, behavioral, and functional magnetic resonance imaging measures to interrogate reward among individuals with eating disorders. However, limitations inherent in each of these methods (e.g., poor temporal resolution) may obscure distinct neurocognitive reward processes, potentially contributing to underdeveloped models of reward dysfunction within eating disorders. The temporal precision of event-related potentials (ERPs), derived from electroencephalography, may thus offer a powerful complementary tool for elucidating the neurocognitive underpinnings of reward. Indeed, a considerable amount of research in other domains of psychopathology (e.g., depression, substance use disorders), as well as studies investigating food reward among non-clinical samples, highlights the utility of ERPs for probing reward processes. However, no study to date has utilized ERPs to directly examine reward functioning in eating disorders.

METHODS

In this paper, we review evidence underscoring the clinical utility of ERP measures of reward, as well as a variety of reward-related tasks that can be used to elicit specific ERP components with demonstrated relevance to reward processing. We then consider the ways in which these tasks/components may be used to help answer a variety of open questions within the eating disorders literature on reward.

RESULTS/DISCUSSION

Given the promise of ERP measures of reward to the field of eating disorders, we ultimately hope to spur and guide research in this currently neglected area.

PUBLIC SIGNIFICANCE

Abnormalities in reward functioning appear to contribute to eating disorders. Event-related potentials (ERPs) offer temporally precise measures of neurocognitive reward processing and thus may be important tools for understanding the relationship between reward and disordered eating. However, research in this area is currently lacking. This paper attempts to facilitate the use of ERPs to study reward among individuals with eating disorders by reviewing the relevant theories and methods.

Decision-Making in Childhood Predicts Prodromal Eating Pathology in Adolescence

OBJECTIVE

Differences in decision-making under conditions of risk have been observed cross-sectionally in clinical groups of people with eating disorders but have never been studied longitudinally or in large cohorts. We investigated whether responses on the Cambridge Gambling Task (CGT), measured in the Millennium Cohort Study in childhood, would predict prodromal eating pathology in adolescence.

METHOD

Regression models were built to explore relationships between CGT variables at age 11 years and prodromal eating pathology (body dissatisfaction, intention to lose weight, dietary restriction, significant under/overweight, and excessive exercise) at 14 years.

RESULTS

In 11,303 boys and girls, those with better quality decision-making were 34% less likely to show an intention to lose weight (b = -0.40, odds ratio [OR] = 0.66, p < 0.05) and 34% less likely to be overweight (b = -0.41, relative risk ratio [RRR] = 0.66, p < 0.05). Those with higher risk-taking were 58% more likely to report dietary restriction (b = 0.45, OR = 1.58, p < 0.05) and 46% more likely to report excessive exercise (b = 0.38, OR = 1.46, p < 0.05). In the complete-cases sample, higher risk-adjustment scores were associated with a 47% increased risk of underweight (b = 0.39, RRR = 1.47, p < 0.05), and better quality of decision-making was associated with a 46% lower risk of overweight (b = -0.60, RRR = 0.54, p < 0.05).

CONCLUSION

Disadvantageous decision-making in childhood may predict prodromal eating pathology in adolescence and might represent a prevention target.

Neural, physiological, and psychological markers of appetitive conditioning in anorexia nervosa: a study protocol

BACKGROUND

Anorexia nervosa (AN) is a chronic and disabling psychiatric condition characterized by low hedonic drive towards food, and is thought to be inclusive of altered dimensions of reward processing. Whether there exists a fundamental aberrancy in the capacity to acquire and maintain de novo hedonic associations-a critical component of hedonic responding-has never been studied in AN.

METHODS

This multi-modal study will employ a 2-day Pavlovian appetitive conditioning paradigm to interrogate the (1) acquisition, (2) extinction, (3) spontaneous recovery and (4) reinstatement of appetitive learning in adolescents and young adults with AN. Participants will be 30 currently ill, underweight individuals with AN; 30 weight-restored individuals with AN; and 30 age-matched healthy controls, all aged 12-22 years. All subjects will undergo clinical assessment, followed by the 2-day appetitive conditioning task during which fMRI, pupillometry, heart rate deceleration, and subjective ratings will be acquired.

DISCUSSION

This study will be the first to interrogate appetitive conditioning in AN-a disorder characterized by altered hedonic responding to food. Results will help establish objective biomarkers of appetitive conditioning in AN and lay the groundwork for developing novel lines of treatment for AN and other psychiatric disorders involving diminished ability to experience pleasure and reward.

TRIAL REGISTRATION

Pending.

INTENDED REGISTRY

Clinicaltrials.gov.

Mesolimbic Neurobehavioral Mechanisms of Reward Motivation in Anorexia Nervosa: A Multimodal Imaging Study

Diminished motivation to pursue and obtain primary and secondary rewards has been demonstrated in anorexia nervosa (AN). However, the neurobehavioral mechanisms underlying the behavioral activation component of aberrant reward motivation remains incompletely understood. This work aims to explore this underexplored facet of reward motivation in AN. We recruited female adolescents with AN, restricting type (n = 32) and a healthy control group (n = 28). All participants underwent functional magnetic resonance imaging (fMRI) while performing a monetary reward task. Diffusion MRI data was also collected to examine the reward motivation circuit's structural connectivity. Behavioral results demonstrated slower speed of reward-seeking behavior in those with AN compared with controls. Accompanying this was lower functional connectivity and reduced white matter structural integrity of the connection between the ventral tegmental area/substantia nigra pars compacta and the nucleus accumbens within the mesolimbic circuit. Further, there was evidence of neurobehavioral decoupling in AN between reward-seeking behavior and mesolimbic regional activation and functional connectivity. Aberrant activity of the bed nucleus of the stria terminalis (BNST) and its connectivity with the mesolimbic system was also evident in AN during the reward motivation period. Our findings suggest functional and structural dysconnectivity within a mesolimbic reward circuit, neurofunctional decoupling from reward-seeking behavior, and abnormal BNST function and circuit interaction with the mesolimbic system. These results show behavioral indicators of aberrant reward motivation in AN, particularly in its activational component. This is mediated neuronally by mesolimbic reward circuit functional and structural dysconnectivity as well as neurobehavioral decoupling. Based on these findings, we suggest a novel circuit-based mechanism of impaired reward processing in AN, with the potential for translation to developing more targeted and effective treatments in this difficult-to-treat psychiatric condition.

Increased self-reported delay of gratification in acutely underweight, but not remitted anorexia nervosa

OBJECTIVE

Laboratory experiments using delay discounting tasks have delivered some evidence of an increased capacity to delay reward in anorexia nervosa (AN). Overall, however, findings have been inconclusive and no comprehensive studies of self-reported tendency to forgo immediate gratification in favor of long-term rewards exist in AN.

METHOD

A total of 71 acutely underweight female inpatients with AN (acAN); 52 women long-term weight-recovered from AN (recAN); and 120 healthy control women completed the Delaying Gratification Inventory (DGI). Fifty-two acAN were reassessed after short-term weight rehabilitation. Separate cross-sectional and longitudinal group comparisons tested for differences in DGI subscales (food, physical pleasure, social interaction, money, and achievement) and total scores.

RESULTS

DGI scores were elevated in acAN even after removing food-related items and accounting for comorbid symptoms. DGI scores remained relatively elevated following short-term weight rehabilitation, but no differences were evident between recAN and HC.

DISCUSSION

This study delivers self-report evidence supporting the notion of an increased propensity to delay gratification in individuals acutely ill with AN which does not appear to change with partial weight restoration alone. A reduction in the tendency to delay reward may thus be an important cognitive correlate of long-term recovery in AN.

Is decision-making impairment an endophenotype of anorexia nervosa?

Background

Patients with anorexia nervosa (AN) show impaired decision-making ability, but it is still unclear if this is a trait marker (i.e., being associated with AN at any stage of the disease) or a state parameter of the disease (i.e., being present only in acutely ill patients), and if it has endophenotypic characteristics. The aim of this study was to determine the endophenotypic, and state- or trait-associated nature of decision-making impairment in AN.

Methods

Ninety-one patients with acute AN (A-AN), 90 unaffected relatives (UR), 23 patients remitted from AN (R-AN), and 204 healthy controls (HC) carried out the Iowa gambling task (IGT). Prospective valence learning (PVL) model was employed to distinguish the cognitive dimensions underlying the decision-making process, that is, learning, consistency, feedback sensitivity, and loss aversion. IGT performance and decision-making dimensions were compared among groups to assess whether they had endophenotypic (i.e., being present in A-AN, UR, and R-AN, but not in HC) and/or trait-associated features (i.e., present in A-AN and R-AN but not in HC).

Results

Patients with A-AN had lower performance at the IGT (p < 0.01), while UR, R-AN, and HC had comparable results. PVL-feedback sensitivity was lower in patients with R-AN and A-AN than in HC (p < 0.01).

Conclusions

Alteration of decision-making ability did not show endophenotypic features. Impaired decision-making seems a state-associated characteristic of AN, resulting from the interplay between trait-associated low feedback sensitivity and state-associated features of the disease.

Beyond Description and Deficits: How Computational Psychiatry Can Enhance an Understanding of Decision-Making in Anorexia Nervosa

PURPOSE OF REVIEW

Despite decades of research, knowledge of the mechanisms maintaining anorexia nervosa (AN) remains incomplete and clearly effective treatments elusive. Novel theoretical frameworks are needed to advance mechanistic and treatment research for this disorder. Here, we argue the utility of engaging a novel lens that differs from existing perspectives in psychiatry. Specifically, we argue the necessity of expanding beyond two historically common perspectives: (1) the descriptive perspective: the tendency to define mechanisms on the basis of surface characteristics and (2) the deficit perspective: the tendency to search for mechanisms associated with under-functioning of decision-making abilities and related circuity, rather than problems of over-functioning, in psychiatric disorders.

RECENT FINDINGS

Computational psychiatry can provide a novel framework for understanding AN because this approach emphasizes the role of computational misalignments (rather than absolute deficits or excesses) between decision-making strategies and environmental demands as the key factors promoting psychiatric illnesses. Informed by this approach, we argue that AN can be understood as a disorder of excess goal pursuit, maintained by over-engagement, rather than disengagement, of executive functioning strategies and circuits. Emerging evidence suggests that this same computational imbalance may constitute an under-investigated phenotype presenting transdiagnostically across psychiatric disorders. A variety of computational models can be used to further elucidate excess goal pursuit in AN. Most traditional psychiatric treatments do not target excess goal pursuit or associated neurocognitive mechanisms. Thus, targeting at the level of computational dysfunction may provide a new avenue for enhancing treatment for AN and related disorders.

Temperament and psychopathology in early childhood predict body dissatisfaction and eating disorder symptoms in adolescence

Eating disorders (ED) are highly impairing and dangerous conditions that typically onset in adolescence. However, very few prospective studies have examined early childhood risk factors for ED pathology. Given well-established links between temperament and psychopathology, examination of these factors could inform prevention efforts. The current multi-method, multi-informant prospective longitudinal study tested whether laboratory-observed and parent-reported temperament and psychiatric disorders at ages 3 and 6 (N = 609) predict body dissatisfaction at ages 12 and 15 and dimensional symptoms of EDs (anorexia nervosa [AN] and bulimia nervosa [BN]) at age 15 (n = 458) in a community sample. Results indicated that early childhood temperament (positive and negative emotionality, perceptual sensitivity, impulsivity, less shyness) and childhood psychopathology (anxiety, oppositional defiant, attention deficit/hyperactivity, and depressive disorders), predicted body dissatisfaction in adolescence. In addition, childhood perceptual sensitivity and oppositional defiant and depressive disorders predicted AN symptoms. Demographic characteristics (female sex, lower levels of fathers' education, and parental marital status) in childhood predicted body dissatisfaction and AN symptoms. No temperament or psychopathology variables predicted BN symptoms. This study is an important first step toward continuing to identify areas of focus for future research on early childhood risk factors for ED symptoms and body dissatisfaction.

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.

Mindfulness-based interventions for eating disorders: The potential to mobilize multiple associative-learning change mechanisms

Mindfulness is a two-component skill that includes mindful awareness (attentional monitoring of present moment experience) and mindful acceptance (adopting an attitude of acceptance toward this experience). Although mindfulness-based interventions (MBIs) are efficacious for many conditions, there is a lack of research on MBIs for eating disorders (EDs). We propose that MBIs may be promising for EDs given their potential to mobilize not one, but multiple associative-learning change mechanisms in EDs-defined as adaptive processes of change involving one of two forms of associative-learning: Pavlovian and operant learning. We hypothesize how MBIs-via increasing either mindful awareness or mindful acceptance-may mobilize up to eight associative-learning change mechanisms, two involving Pavlovian learning, and six involving operant learning. We also elaborate on similarities and differences between MBIs and CBT approaches for EDs, as well as opportunities for synergy. Finally, we present recommendations for future research related to the development and evaluation of novel MBI interventions for EDs and the testing of mechanisms and patient-treatment matching hypotheses.

Disorder specific rewarding stimuli in anorexia nervosa

OBJECTIVE

To enhance our understanding of reward stimuli in anorexia nervosa (AN) and to provide a basis for future research on reward processes, disorder specific reward stimuli as well as primary and secondary reinforcers were investigated.

METHOD

We developed a set of pictures with "disorder specific reward" stimuli, with the six subcategories "sport," "losing weight," "healthy food," "discipline," "thin bodies," "appreciation of others," and evaluated reward ratings of these "disorder specific reward" stimuli as well as "erotic," "high caloric," and "neutral" stimuli in 25 patients with AN and 25 participants in the comparison group (CG).

RESULTS

We found a significant main effect for picture category and a significant interaction. The reward ratings were higher in patients with AN compared with CG for the "disorder specific reward" stimuli. In the reward subcategories, patients with AN had higher reward ratings compared with CG in all categories except of healthy food. The "disorder specific reward" stimuli of the categories "sport," "losing weight," and "healthy food" showed higher reward ratings compared with the categories "discipline," "thin bodies," and "appreciation of others" in patients with AN.

DISCUSSION

The previously used category "thin bodies" used to investigate the reward system might be less effective compared with stimuli from the categories "sport," "losing weight," and "healthy food."

An empirical taxonomy of reward response patterns in a transdiagnostic eating disorder sample

Reward response patterns may contribute to risk and maintenance of eating disorders (EDs), and there may be clinically meaningful heterogeneity in behavioral responses to different actual and anticipated rewards across ED diagnoses. We used an empirical approach to classify individuals with EDs based on self-reported tendencies for responding to reward-related stimuli. Latent profile analysis was conducted in a transdiagnostic ED sample (N = 104) using Temperament and Character Inventory (Cloninger et al., 1993) subscales to categorize participants on reward responses of behavioral activation towards immediate, hedonic rewards (Novelty Seeking subscale), persistence towards long-term rewards (Persistence subscale), and maintenance by social rewards (Reward Dependence subscale) rewards. Two profiles were identified: (1) Behavioral Activation group (elevated Novelty Seeking; n = 62); and (b) Behavioral Persistence group (elevated Persistence; n = 42). Generalized linear models comparing profiles showed that frequency of these reward response profiles did not differ in probable AN, BN, or OSFED groups; however, individuals with probable BED more often demonstrated the Behavioral Activation profile (p = .041). These profiles exhibited comparable ED severity, but different presentations. Across probable ED diagnoses, the Behavioral Activation group reported greater binge eating (p = .006, d = 0.32) and had higher BMIs (p = .001, d = 0.57); the Behavioral Persistence group endorsed greater driven exercise (p = .042, d = 0.33). Categorization by activation to novel, immediate rewards versus persistence towards long-term rewards was associated with different symptoms across diagnoses, potentially supporting the role of specific reward response profiles in ED phenomenology.

Avoidance in Anorexia Nervosa: Towards a research agenda

Anorexia Nervosa is a severe and disabling mental disorder and a huge challenge to treat. Intense fears of e.g., food, eating, weight gain and social evaluation are core features of anorexia nervosa and obstacles during treatment. The perceived threats trigger avoidance and safety behaviors like highly restrictive eating, strict eating rules, vomiting and body checking, to minimize feared outcomes. The role of avoidance in anorexia nervosa is however hardly studied experimentally. In the present article, the focus is on a new transdiagnostic research agenda featuring both basic and clinical experimental research into avoidance as a most important mechanism maintaining the eating disorder. Avoidance learning and the generalization of learned avoidance behaviors are discussed, as well as safety behaviors and the need for inhibitory learning as a treatment target during exposure therapy.

Adapting a neuroscience-informed intervention to alter reward mechanisms of anorexia nervosa: a novel direction for future research

Accumulating psychobiological data implicate reward disturbances in the persistence of anorexia nervosa (AN). Evidence suggests that individuals with AN demonstrate decision-making deficits similar to those with mood and anxiety disorders that cause them to under-respond to many conventionally rewarding experiences (e.g., eating, interacting socially). In contrast, unlike individuals with other psychiatric disorders, individuals with AN simultaneously over-respond to rewards associated with eating-disorder behaviors (e.g., restrictive eating, exercising). This pattern of reward processing likely perpetuates eating-disorder symptoms, as the rewards derived from eating-disorder behaviors provide temporary relief from the anhedonia associated with limited responsivity to other rewards. Positive Affect Treatment (PAT) is a cognitive-behavioral intervention designed to target reward deficits that contribute to anhedonia in mood and anxiety disorders, including problems with reward anticipation, experiencing, and learning. PAT has been found to promote reward responsivity and clinical improvement in mood and anxiety disorders. This manuscript will: (1) present empirical evidence supporting the promise of PAT as an intervention for AN; (2) highlight nuances in the maintaining processes of AN that necessitate adaptations of PAT for this population; and (3) suggest future directions in research on PAT and other reward-based treatments that aim to enhance clinical outcomes for AN.

From Desire to Dread-A Neurocircuitry Based Model for Food Avoidance in Anorexia Nervosa

Anorexia nervosa is a severe psychiatric illness associated with food avoidance. Animal models from Berridge et al. over the past decade showed that environmental ambience, pleasant or fear inducing, can trigger either appetitive (desire) or avoidance (dread) behaviors in animals via frontal cortex, nucleus accumbens dopamine D1 and D2 receptors, and hypothalamus. Those mechanisms could be relevant for understanding anorexia nervosa. However, models that translate animal research to explain the psychopathology of anorexia nervosa are sparse. This article reviews animal and human research to find evidence for whether this model can explain food avoidance behaviors in anorexia nervosa. Research on anorexia nervosa suggests fear conditioning to food, activation of the corticostriatal brain circuitry, sensitization of ventral striatal dopamine response, and alterations in hypothalamic function. The results support the applicability of the animal neurocircuitry derived model and provide directions to further study the pathophysiology that underlies anorexia nervosa.

Current directions in biomarkers and endophenotypes for anorexia nervosa: A scoping review

There are currently no validated biomarkers for anorexia nervosa (AN), though recent literature suggests an increased research interest in this area. Biomarkers are objective, measurable indicators of illness that can be used to assist with diagnosis, risk assessment, and tracking of illness state. Related to biomarkers are endophenotypes, which are quantifiable phenomena that are distinct from symptoms and which link genes to manifest illness. In this scoping review, we sought to provide a summary of recent research conducted in the pursuit of biomarkers and endophenotypes for AN. The findings indicate that a number of possible biomarkers which can assess the presence or severity of AN independently of weight status, including psychophysical (e.g., eye-tracking) and biological (e.g., immune, endocrine, metabolomic, neurobiological) markers, are currently under investigation. However, this research is still in early phases and lacking in replication studies. Endophenotype research has largely been confined to the study of several neurocognitive features, with mixed evidence to support their classification as possible endophenotypes for the disorder. The study of biomarkers and endophenotypes in AN involves significant challenges due to confounding factors of illness-related sequalae, such as starvation. Future research in these areas must prioritise direct evaluation of the sensitivity, specificity and test-retest reliability of proposed biomarkers and enhanced control of confounding physical consequences of AN in the study of biomarkers and endophenotypes.

Targeting maladaptive overcontrol with radically open dialectical behaviour therapy in a day programme for adolescents with restrictive eating disorders: an uncontrolled case series

BACKGROUND

Radically Open Dialectical Behaviour Therapy (RO-DBT) was developed to target maladaptive overcontrol, a proposed core difficulty of restrictive eating disorders. RO-DBT is now the main group treatment model at the Intensive day Treatment Programme (ITP), Maudsley Hospital. This ITP case series aimed to investigate whether overcontrol is associated with restrictive eating disorder symptoms in adolescents and to evaluate ITP outcomes since RO-DBT skills classes were introduced.

METHOD

Self-report measures of eating disorder symptoms and temperament, personality and social characteristics linked to overcontrol were collected at assessment and discharge from ITP for all consecutive adolescents who attended between February 2015 and January 2019 (N = 131). Weight change, global outcomes and treatment needs post-ITP were also recorded.

RESULTS

Eating disorder symptoms at assessment were significantly correlated with overcontrol factors, including social connectedness (r = -.67), reward responsivity (r = -.54), and cognitive inflexibility (r = .52). Adolescents stayed in ITP on average 13.40 weeks. 70.8% had a Good-Intermediate outcome on Morgan-Russell scale. 4.6% did not respond and were referred to inpatient treatment from ITP. Significant improvements in drive for thinness (d = .33), depressive mood (d = .41), social connectedness (d = .48), and emotional expressiveness (d = .97) were reported at discharge. No changes were observed in perfectionism or negative temperament.

CONCLUSIONS

This study offers preliminary evidence that eating disorder symptoms are associated with overcontrol factors in adolescence and that they can improve with RO-DBT informed day programme treatment. RO-DBT is a promising treatment that offers a new way of conceptualising treatment targets and recovery for adolescent restrictive eating disorders.

Conceptualizing eating disorder psychopathology using an anxiety disorders framework: Evidence and implications for exposure-based clinical research

Eating disorders (EDs) and anxiety disorders (ADs) evidence shared risk and significant comorbidity. Recent advances in understanding of anxiety-based disorders may have direct application to research and treatment efforts for EDs. The current review presents an up-to-date, behavioral conceptualization of the overlap between anxiety-based disorders and EDs. We identify ways in which anxiety presents in EDs, consider differences between EDs and ADs relevant to treatment adaptions, discuss how exposure-based strategies may be adapted for use in ED treatment, and outline directions for future mechanistic, translational, and clinical ED research from this perspective. Important research directions include: simultaneous examination of the extent to which EDs are characterized by aberrant avoidance-, reward-, and/or habit-based neurobiological and behavioral processes; improvement in understanding of how nutritional status interacts with neurobiological characteristics of EDs; incorporation of a growing knowledge of biobehavioral signatures in ED treatment planning; development of more comprehensive exposure-based treatment approaches for EDs; testing whether certain exposure interventions for AD are appropriate for EDs; and improvement in clinician self-efficacy and ability to use exposure therapy for EDs.