Altered Neural Efficiency of Decision Making During Temporal Reward Discounting in Anorexia Nervosa

Cognitive and motor impulsivity in the healthy brain, and implications for eating disorders and obesity: A coordinate-based meta-analysis and systematic review

Alterations in the impulse-control balance, and in its neural bases, have been reported in obesity and eating disorders (EDs). Neuroimaging studies suggest a role of fronto-parietal networks in impulsive behaviour, with evaluation and anticipatory processes additionally recruiting meso-limbic regions. However, whether distinct facets of cognitive and motor impulsivity involve common vs. specific neural correlates remains unclear. We addressed this issue through Activation Likelihood Estimation (ALE) meta-analyses of fMRI studies on delay discounting (DD) and go/no-go (GNG) tasks, alongside conjunction and subtraction analyses. We also performed systematic reviews of neuroimaging studies using the same tasks in individuals with obesity or EDs. ALE results showed consistent activations in the striatum, anterior/posterior cingulate cortex, medial/left superior frontal gyrus and left supramarginal gyrus for impulsive choices in DD, while GNG tasks elicited mainly right-lateralized fronto-parietal activations. Conjunction and subtraction analyses showed: i) common bilateral responses in the caudate nucleus; ii) DD-specific responses in the ventral striatum, anterior/posterior cingulate cortex, left supramarginal and medial frontal gyri; iii) GNG-specific activations in the right inferior parietal cortex. Altered fronto-lateral responses to both tasks are suggestive of dysfunctional cortico-striatal balance in obesity and EDs, but these findings are controversial due to the limited number of studies directly comparing patients and controls. Overall, we found evidence for distinctive neural correlates of the motor and cognitive facets of impulsivity: the right inferior parietal lobe underpins action inhibition, whereas fronto-striatal regions and the left supramarginal gyrus are related to impulsive decision-making. While showing that further research on clinical samples is required to better characterize the neural bases of their behavioural changes, these findings help refining neurocognitive model of impulsivity and highlight potential translational implications for EDs and obesity treatment.

Habits and Persistent Food Restriction in Patients with Anorexia Nervosa: A Scoping Review

The aetiology of anorexia nervosa (AN) presents a puzzle for researchers. Recent research has sought to understand the behavioural and neural mechanisms of these patients' persistent choice of calorie restriction. This scoping review aims to map the literature on the contribution of habit-based learning to food restriction in AN. PRISMA-ScR guidelines were adopted. The search strategy was applied to seven databases and to grey literature. A total of 35 studies were included in this review. The results indicate that the habit-based learning model has gained substantial attention in current research, employing neuroimaging methods, scales, and behavioural techniques. Food choices were strongly associated with dorsal striatum activity, and habitual food restriction based on the self-report restriction index was associated with clinical impairment in people chronically ill with restricting AN. High-frequency repetitive transcranial magnetic stimulation (HF-rTMS) and Regulating Emotions and Changing Habits (REaCH) have emerged as potential treatments. Future research should employ longitudinal studies to investigate the time required for habit-based learning and analyse how developmental status, such as adolescence, influences the role of habits in the progression and severity of diet-related illnesses. Ultimately, seeking effective strategies to modify persistent dietary restrictions controlled by habits remains essential.

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.

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.

"Your mind doesn't have room for anything else": a qualitative study of perceptions of cognitive functioning during and after recovery from anorexia nervosa

BACKGROUND

Past research has indicated the presence of cognitive difficulties in individuals with anorexia nervosa (AN), although it is unclear how these are experienced in real life. Moreover, it is unclear how and whether the experience of cognitive difficulties changes in nature and intensity over the course of the illness and following recovery.

METHODS

Twenty-one female participants (AN = 11; recovered AN = 10) participated in online semi-structured interviews, utilising open-ended questions and exploring topics relating to their experiences of their cognitive function, changes over time and their perspectives on the future. Reflexive thematic analysis was conducted on the resulting transcripts.

RESULTS

Six themes were identified, centred around the effects of the illness on mental and physical function, cognition, adaptation to living with the illness, similarities between AN and other psychopathology, tentative optimism for the future and recovery as a representation of liberation. Whilst respondents with AN appeared to perform remarkably well in their professional and educational lives, the cognitive difficulties were described as significantly impacting their ability to engage in life, particularly in the context of leisure and socialising. Respondents recovered from AN noted the importance of developing a non-AN identity as well as better emotion-regulation skills as central to recovery.

CONCLUSIONS

Whilst people with AN may be able to adapt their lives to the demands of the illness, they report significant cognitive difficulties that interfere with their engagement in many aspects of daily life. This should be considered by professionals working in the clinical management of AN. Treatments focused on ameliorating cognitive difficulties, and promoting emotional regulation and identity in AN are warranted.

The neural correlates of socio-cognitive factors and eating disorders in young people: A systematic review

BACKGROUND

Although the primary aetiology of Eating Disorders (ED) remains unknown, research suggests a complex interplay of biological, psychological, and cultural/environmental factors. This paper aims to systematically review the literature on neuroimaging studies that measure socio-cognitive factors, in the context of body dissatisfaction and EDs in young people. Specifically, our aim was to identify patterns in the findings linked to social media-type behaviours.

METHODS

The review was conducted in accordance with PRISMA guidelines using PubMed, Scopus, and Web of Science databases. 799 papers were identified in the database search and 38 studies were selected based on exclusion and inclusion criteria. Selected studies were assessed using the National Institute of Health study quality assessment tool.

RESULTS

Findings point to state-related impairments in inhibitory control and salient emotional processing. Anorexia Nervosa(AN) showed impaired set-shifting abilities, working memory and decision making, while altered activation in attention networks and associated difficulties with conflict resolution were seen for Bulimia Nervosa(BN) and Other Specified Feeding and Eating Disorders(OSFED). AN and BN also demonstrated altered sensitivity to food-related stimuli in striatal regions, suggesting aberrant top-down emotional-cognitive control. ED participants also show deficits in body representation, impaired control over social behaviours and altered integration of visual and body perception.

DISCUSSION

These findings support the notion that socio-cognitive dysfunctions in ED are underpinned by a distributed network of structural and functional brain changes which influence the way young people with ED interact with and respond to social media, and ultimately places at them at increased risk for body image disturbances. This Review was registered with the PROSPERO International Register of Systematic Reviews, Registration number CRD42021270696.

Increased Habit Frequency in the Daily Lives of Patients with Acute Anorexia Nervosa

Strict eating routines and frequent rigid behavior patterns are commonly observed in patients with anorexia nervosa (AN). A recent theory proposes that while these behaviors may have been reinforced initially, they later become habitual. To date, however, research has been overly focused on eating-disorder (ED)-related habits. Over the course of seven days, we applied an ecological momentary assessment (EMA) to investigate the habit frequency and strength of ED-specific (food intake) and ED-unspecific (hygiene) habits in the daily lives of a sample of n = 57 AN and n = 57 healthy controls (HC). The results of the hierarchical models revealed that habits were significantly more likely in patients compared with HC for both categories, independently. Furthermore, a lower body mass index (BMI) was associated with increased habit frequency in AN. Our study strengthens the habit theory of AN by showing the relevance of habits beyond ED-specific behavioral domains. This also supports the development of innovative therapeutic interventions targeting habitual behavior in EDs.

Real-Life Self-Control Conflicts in Anorexia Nervosa: An Ecological Momentary Assessment Investigation

Background

Individuals with anorexia nervosa (AN) are often thought to show heightened self-control and increased ability to inhibit desires. In addition to inhibitory self-control, antecedent-focused strategies (e.g., cognitive reconstrual—the re-evaluation of tempting situations) might contribute to disorder maintenance and enable disorder-typical, maladaptive behaviors.

Methods

Over a period of 14 days, 40 acutely underweight young female patients with anorexia nervosa (AN) and 40 healthy control (HC) participants reported their affect and behavior in self-control situations via ecological momentary assessment during inpatient treatment (AN) and everyday life (HC). Data were analyzed via hierarchical analyses (linear and logistic modeling).

Results

Conflict strength had a significantly lower impact on self-control success in AN compared to HC. While AN and HC did not generally differ in the number or strength of self-control conflicts or in the percentage of self-control success, AN reported self-controlled behavior to be less dependent on conflict strength.

Conclusions

While patients with AN were not generally more successful at self-control, they appeared to resolve self-control conflicts more effectively. These findings suggest that the magnitude of self-control conflicts has comparatively little impact on individuals with AN, possibly due to the use of antecedent-focused strategies. If confirmed, cognitive-behavioral therapy might focus on and help patients to exploit these alternative self-control strategies in the battle against their illness.

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.

Functional Abnormality of the Executive Control Network in Individuals With Obesity During Delay Discounting

Individuals with obesity (OB) prefer immediate rewards of food intake over the delayed reward of healthy well-being achieved through diet management and physical activity, compared with normal-weight controls (NW). This may reflect heightened impulsivity, an important factor contributing to the development and maintenance of obesity. However, the neural mechanisms underlying the greater impulsivity in OB remain unclear. Therefore, the current study employed functional magnetic resonance imaging with a delay discounting (DD) task to examine the association between impulsive choice and altered neural mechanisms in OB. During decision-making in the DD task, OB compared with NW had greater activation in the dorsolateral prefrontal cortex (DLPFC) and posterior parietal cortex, which was associated with greater discounting rate and weaker cognitive control as measured with the Three-Factor Eating Questionnaire (TFEQ). In addition, the association between DLPFC activation and cognitive control (TFEQ) was mediated by discounting rate. Psychophysiological interaction analysis showed decreased connectivity of DLPFC-inferior parietal cortex (within executive control network [ECN]) and angular gyrus-caudate (ECN-reward) in OB relative to NW. These findings reveal that the aberrant function and connectivity in core regions of ECN and striatal brain reward regions underpin the greater impulsivity in OB and contribute to abnormal eating behaviors.

A review of effort-based decision-making in eating and weight disorders

Effort-based decision-making provides a framework to understand the mental computations estimating the amount of work ("effort") required to obtain a reward. The aim of the current review is to systematically synthesize the available literature on effort-based decision-making across the spectrum of eating and weight disorders. More specifically, the current review summarises the literature examining whether 1) individuals with eating disorders and overweight/obesity are willing to expend more effort for rewards compared to healthy controls, 2) if particular components of effort-based decision-making (i.e. risk, discounting) relate to specific binge eating conditions, and 3) how individual differences in effort and reward -processing measures relate to eating pathology and treatment measures. A total of 96 studies were included in our review, following PRISMA guidelines. The review suggests that individuals with binge eating behaviours 1) are more likely to expend greater effort for food rewards, but not monetary rewards, 2) demonstrate greater decision-making impairments under risk and uncertainty, 3) prefer sooner rather than delayed rewards for both food and money, and 4) demonstrate increased implicit 'wanting' for high fat sweet foods. Finally, individual differences in effort and reward -processing measures relating to eating pathology and treatment measures are also discussed.

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."

Resting-state functional network connectivity underlying eating disorder symptoms in healthy young adults

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This study examined the resting-state functional network connectivity underlying eating disorder symptoms in a large sample of healthy young adults (n = 693).

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Individuals with higher levels of eating disorder symptoms displayed weaker intra-network connectivity of the executive control network and basal ganglia network, as well as weaker inter-network connectivity in the three examined networks (i.e., the executive control network, basal ganglia network, and default mode network).

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The findings suggest that these neural circuits may play a key role in symptoms of disordered eating in healthy adults. They further reveal that the less efficient information exchange within and between intrinsic networks associated with self-referential thinking, inhibitory control, and reward sensitivity are strongly related to eating disorder symptoms.

Previous neuroimaging research of eating disorders such as anorexia nervosa and bulimia nervosa has mainly focused on clinical patients, indicating the crucial role of intrinsic connectivity networks involved in aberrant behavioral control (i.e., executive control network), reward reactivity (i.e., basal ganglia network), and excessive self-focused and body-focused ruminations (i.e., default mode network) in the onset and maintenance of eating disturbances. However, examinations of large-scale resting-state networks that support the role of cognitive control, reward sensitivity, and self-directed thinking in disordered eating have rarely involved non-clinical samples from the general population. This study, involving a total of 693 healthy young adults (68.69% females; mean age, 18.37 years), investigated these issues by using pre-defined functional regions of interest from the executive control network, basal ganglia network, default mode network, and a seed-based region of interest-to-region of interest approach. After statistically controlling for differences in age, sex, body mass index, and head motion, we observed significant associations of higher levels of eating disorder symptoms, especially bulimia-type eating (i.e., binge eating and a combination of binge eating and compensatory behaviors, such as purging via self-induced vomiting or laxative use, and compulsive exercise), with weaker intra-network and inter-network functional synchrony. These results remained significant after excluding underweight, overweight, and obese participants. These findings suggest that these neural circuits may play a key role in the symptoms of disordered eating in healthy adults. They further reveal that the less efficient information exchange within and between intrinsic networks associated with self-referential thinking, inhibitory control, and reward sensitivity are strongly related to eating disorder symptoms.

Hunger-driven adaptive prioritization of behavior

In order to survive, an animal must adapt its behavioral priorities to accommodate changing internal and external conditions. Hunger, a universally recognized interoceptive signal, promotes food intake though increasingly well-understood neural circuits. Less understood, is how hunger is integrated into the neural computations that guide nonfeeding behaviors. Within the brain, agouti-related peptide neurons in the arcuate nucleus of the hypothalamus have been found to powerfully stimulate feeding in addition to mediating other hunger-driven behavioral phenotypes. In this review, we compile the behavioral plasticity downstream of hunger and present identified or potential molecular and neural circuit mechanisms. We catalogue hunger's ability to increase exploration, decrease anxiety, and alter social behavior, among other phenotypes. Finally, we suggest paths forward for understanding hunger-driven behavioral adaptation and discuss the benefits of understanding state-dependent modulation of neural circuits controlling behavior.

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.

Can't decide how much to EAT? Effort variability for reward is associated with cognitive restraint

Food intake is inherently variable and often characterized by episodical restraint or overeating (uncontrolled eating). Such heightened variability in intake has been associated with higher variability in the brain response to food reward, but it is an open issue whether comparable associations with elevated variability in reward seeking exist. Here, we assessed whether restraint and uncontrolled eating as markers of trait-like variability in eating are associated with higher intra-individual variability in reward seeking as captured by a cost-benefit paradigm. To test this hypothesis, 81 healthy, overnight-fasting participants (M_BMI = 23.0 kg/m² ± 3.0) completed an effort allocation task (EAT) twice. In the EAT, participants had to exert physical effort to earn monetary and food rewards and indicated levels of wanting through visual analog scales (VAS). As predicted, we found that greater trial-by-trial effort variability was associated with lower scores on cognitive restraint, r_p(78) = -0.28, p = .011 (controlled for average effort). In line with previous findings, higher wanting variability was associated with higher BMI, r_p(78) = 0.25, p = .026 (controlled for average effort). Collectively, our results support the idea that higher variability in reward seeking is a potential risk factor for eating beyond homeostatic need. Since associations with variability measures of reward exceeded associations with average reward seeking, our findings may indicate that variability in the representation of the reward value could be a crucial aspect driving fluctuations in food intake.

Study protocol of comprehensive risk evaluation for anorexia nervosa in twins (CREAT): a study of discordant monozygotic twins with anorexia nervosa

BACKGROUND

Anorexia nervosa (AN) is a severe disorder, for which genetic evidence suggests psychiatric as well as metabolic origins. AN has high somatic and psychiatric comorbidities, broad impact on quality of life, and elevated mortality. Risk factor studies of AN have focused on differences between acutely ill and recovered individuals. Such comparisons often yield ambiguous conclusions, as alterations could reflect different effects depending on the comparison. Whereas differences found in acutely ill patients could reflect state effects that are due to acute starvation or acute disease-specific factors, they could also reflect underlying traits. Observations in recovered individuals could reflect either an underlying trait or a "scar" due to lasting effects of sustained undernutrition and illness. The co-twin control design (i.e., monozygotic [MZ] twins who are discordant for AN and MZ concordant control twin pairs) affords at least partial disambiguation of these effects.

METHODS

Comprehensive Risk Evaluation for Anorexia nervosa in Twins (CREAT) will be the largest and most comprehensive investigation of twins who are discordant for AN to date. CREAT utilizes a co-twin control design that includes endocrinological, neurocognitive, neuroimaging, genomic, and multi-omic approaches coupled with an experimental component that explores the impact of an overnight fast on most measured parameters.

DISCUSSION

The multimodal longitudinal twin assessment of the CREAT study will help to disambiguate state, trait, and "scar" effects, and thereby enable a deeper understanding of the contribution of genetics, epigenetics, cognitive functions, brain structure and function, metabolism, endocrinology, microbiology, and immunology to the etiology and maintenance of AN.

Heterogeneity in Fear Processing across and within Anxiety, Eating, and Compulsive Disorders

BACKGROUND

To assess within and across diagnosis variability we examined fear processing in healthy controls (HC) and three diagnostic groups that share symptoms of pathological anxiety: obsessive compulsive disorder (OCD); social anxiety disorder (SAD), and anorexia nervosa (AN).

METHODS

Unmedicated adults (N=166) participated in a paradigm assessing associative fear acquisition, extinction, extinction recall, and fear renewal. Data were analyzed from two perspectives: comparison of each disorder to HC and exploratory latent class analysis (LCA) of the combined data.

RESULTS

The diagnosis-based analyses indicated significantly increased fear renewal in OCD and trends toward decreased extinction recall in OCD and increased renewal in SAD. The LCA indicated four Response Types, none of which were congruent with the diagnostic categories. Most participants had a normative response (50%) or a moderate extinction recall deficit (30%). The two remaining groups (8% each) had more extreme responses: one showed complete failure of extinction recall; the other persistent arousal in expectation of, but prior to, actual conditioning (threat sensitivity).

LIMITATIONS

Due to small sample size (N=20) results for AN are regarded as preliminary.

CONCLUSIONS

Our diagnosis-based findings are consistent with previous data suggesting an association between pathological anxiety and difficulties maintaining fear extinction. The LCA reveal substantial within-diagnosis heterogeneity in fear processing and support inclusion of empirically driven approaches as a complement to standard analyses. This heterogeneity may also have implications for treatment, particularly cognitive behavioral therapy, which relies on strengthening extinction recall and requires patients to tolerate anxious expectation in order to engage with feared situations.

Metabolic state and value-based decision-making in acute and recovered female patients with anorexia nervosa

BACKGROUND

Patients with anorexia nervosa forgo eating despite emaciation and severe health consequences. Such dysfunctional decision-making might be explained by an excessive level of self-control, alterations in homeostatic and hedonic regulation, or an interplay between these processes. We aimed to understand value-based decision-making in anorexia nervosa and its association with the gut hormone ghrelin. Besides its homeostatic function, ghrelin has been implicated in the hedonic regulation of appetite and reward via the modulation of phasic dopamine signalling.

METHODS

In a cross-sectional design, we studied acutely underweight (n = 94) and recovered (n = 37) patients with anorexia nervosa of the restrictive subtype, as well as healthy control participants (n = 119). We assessed plasma concentrations of desacyl ghrelin and parameters of delay discounting, probability discounting for gains and losses, and loss aversion.

RESULTS

Recovered patients displayed higher risk aversion for gains, but we observed no group differences for the remaining decision-making parameters. Desacyl ghrelin was higher in acutely underweight and recovered participants with anorexia nervosa relative to healthy controls. Moreover, we found a significant group × desacyl ghrelin interaction in delay discounting, indicating that in contrast to healthy controls, acutely underweight patients with anorexia nervosa who had high desacyl ghrelin concentrations preferably chose the delayed reward option.

LIMITATIONS

We probed decision-making using monetary rewards, but patients with anorexia nervosa may react differently to disorder-relevant stimuli. Furthermore, in contrast to acyl ghrelin, the functions of desacyl ghrelin are unclear. Therefore, the interpretation of the results is preliminary.

CONCLUSION

The propensity for risk aversion as found in recovered patients with anorexia nervosa could help them successfully complete therapy, or it could reflect sequelae of the disorder. Conversely, ghrelin findings might be related to a mechanism contributing to disease maintenance; that is, in acutely underweight anorexia nervosa, a hungry state may facilitate the ability to forgo an immediate reward to achieve a (dysfunctional) long-term goal.

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.

Neural correlates of delay discount alterations in addiction and psychiatric disorders: A systematic review of magnetic resonance imaging studies

Delay discounting (DD) represents decreased subjective value for delayed reward relative to the same reward at present. The concept of DD has been applied for pathophysiology of addiction and psychiatric disorders. However, the detailed neuroimaging correlates of DD underlying pathophysiology still remain unclear. Thus, we conducted a systematic review to investigate neural correlates of DD on magnetic resonance imaging studies among addiction and psychiatric disorders. Specific search terms were set on PubMed to identify relevant articles. Initial search identified 551 records and 31 studies met the inclusion criteria. The present review revealed that greater DD was correlated with increased activity in areas related to reward evaluation and prediction as well as decreased activity in areas related to cognitive control. Healthy controls showed smaller changes in activities of these areas associated with DD when compared to patient groups. As the neural basis related to DD, three neural networks have been proposed that are associated with the actions of short-term interests and long-term benefits. Among the three potential neural networks on DD, the first one included the ventromedial prefrontal cortex and ventral striatum and implicated in evaluating reward values, the second network included the anterior cingulate cortex and linked to cognitive control, and the third network included the middle temporal gyrus and was involved in predictions and affection. This review generated consistent findings on the neural basis of DD among patients with addiction and psychiatric disorders, which may represent the pathophysiology related to DD and impulsivity of mental illness.

Strengthened Default Mode Network Activation During Delay Discounting in Adolescents with Anorexia Nervosa After Partial Weight Restoration: A Longitudinal fMRI Study

The capacity of patients with anorexia nervosa (AN) to resist food-based rewards is often assumed to reflect excessive self-control. Previous cross-sectional functional magnetic resonance imaging (fMRI) studies utilizing the delay discounting (DD) paradigm, an index of impulsivity and self-control, suggested altered neural efficiency of decision-making in acutely underweight patients (acAN) and a relative normalization in long-term, weight-recovered individuals with a history of AN (recAN). The current longitudinal study tested for changes in functional magnetic resonance imaging (fMRI) activation during DD associated with intensive weight restoration treatment. A predominately adolescent cohort of 22 female acAN patients (mean age—15.5 years) performed an established DD paradigm during fMRI at the beginning of hospitalization and again after partial weight restoration (≥12% body mass index (BMI) increase). Analyses investigated longitudinal changes in both reward valuation and executive decision-making processes. Additional exploratory analyses included comparisons with data acquired in aged-matched healthy controls (HC) as well as probes of functional connectivity between empirically identified nodes of the “task-positive” frontoparietal control network (FPN) and “task-negative” default-mode network (DMN). While treatment was not associated with changes in behavioral DD parameters or activation, specific to reward processing, deactivation of the DMN during decision-making was significantly less pronounced following partial weight restoration. Strengthened DMN activation during DD might reflect a relative relaxation of cognitive overcontrol or improved self-referential, decision-making. Together, our findings present further evidence that aberrant decision-making in AN might be remediable by treatment and, therefore, might constitute an acute effect rather than a core trait variable of the disorder.

Intact value-based decision-making during intertemporal choice in women with remitted anorexia nervosa? An fMRI study

BACKGROUND

Extreme restrictive food choice in anorexia nervosa is thought to reflect excessive self-control and/or abnormal reward sensitivity. Studies using intertemporal choice paradigms have suggested an increased capacity to delay reward in anorexia nervosa, and this may explain an unusual ability to resist immediate temptation and override hunger in the long-term pursuit of thinness. It remains unclear, however, whether altered delay discounting in anorexia nervosa constitutes a state effect of acute illness or a trait marker observable after recovery.

METHODS

We repeated the analysis from our previous fMRI investigation of intertemporal choice in acutely underweight patients with anorexia nervosa in a sample of weight-recovered women with anorexia nervosa (n = 36) and age-matched healthy controls (n = 36) who participated in the same study protocol. Follow-up analyses explored functional connectivity separately in both the weight-recovered/healthy controls sample and the acute/healthy controls sample.

RESULTS

In contrast to our previous findings in acutely underweight patients with anorexia nervosa, we found no differences between weight-recovered patients with anorexia nervosa and healthy controls at either behavioural or neural levels. New analysis of data from the acute/healthy controls sample sample revealed increased coupling between dorsal anterior cingulate cortex and posterior brain regions as a function of decision difficulty, supporting the hypothesis of altered neural efficiency in the underweight state.

LIMITATIONS

This was a cross-sectional study, and the results may be task-specific.

CONCLUSION

Although our results underlined previous demonstrations of divergent temporal reward discounting in acutely underweight patients with anorexia nervosa, we found no evidence of alteration in patients with weight-recovered anorexia nervosa. Together, these findings suggest that impaired valuebased decision-making may not constitute a defining trait variable or “scar” of the disorder.

Abnormal Spontaneous Regional Brain Activity in Young Patients With Anorexia Nervosa

OBJECTIVE

Functional magnetic resonance imaging (fMRI) studies have repeatedly shown alterations in patients with anorexia nervosa (AN). These alterations might be driven by baseline signal characteristics such as the (fractional) amplitude of low frequency fluctuations (fALFF/ALFF), as well as regional signal consistency (ie, regional homogeneity [ReHo]) within circumscribed brain regions. Previous studies have also demonstrated gray matter (pseudo-) atrophy in underweight individuals with AN. Here we study fALFF/ALFF and ReHo in predominantly adolescent patients with AN, while taking gray matter changes into consideration.

METHOD

Resting state fMRI data were acquired from a sample of 148 female volunteers: 74 underweight patients with AN and 74 age-matched female healthy controls (HC).

RESULTS

Group differences for fALFF and ReHo measures were found in several AN-relevant brain regions, including networks related to cognitive control, habit formation, and the ventral visual stream. Furthermore, the magnitude of correlation between gray matter volume/thickness and fALFF and ReHo were reduced in AN compared to HC.

CONCLUSION

Abnormal local resting state characteristics in AN-related brain-networks as well as reduced structure-function relationships may help to explain previously reported task-related and classical resting state neural alterations in underweight AN. Patients with AN may serve as a valuable population for investigating dynamic changes in the relationships between brain structure and function.

Delay Discounting as a Transdiagnostic Process in Psychiatric Disorders: A Meta-analysis

IMPORTANCE

Delay discounting is a behavioral economic index of impulsive preferences for smaller-immediate or larger-delayed rewards that is argued to be a transdiagnostic process across health conditions. Studies suggest some psychiatric disorders are associated with differences in discounting compared with controls, but null findings have also been reported.

OBJECTIVE

To conduct a meta-analysis of the published literature on delay discounting in people with psychiatric disorders.

DATA SOURCES

PubMed, MEDLINE, PsycInfo, Embase, and Web of Science databases were searched through December 10, 2018. The psychiatric keywords used were based on DSM-IV or DSM-5 diagnostic categories. Collected data were analyzed from December 10, 2018, through June 1, 2019.

STUDY SELECTION

Following a preregistered Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) protocol, 2 independent raters reviewed titles, abstracts, and full-text articles. English-language articles comparing monetary delay discounting between participants with psychiatric disorders and controls were included.

DATA EXTRACTION AND SYNTHESIS

Hedges g effect sizes were computed and random-effects models were used for all analyses. Heterogeneity statistics, one-study-removed analyses, and publication bias indices were also examined.

MAIN OUTCOMES AND MEASURES

Categorical comparisons of delay discounting between a psychiatric group and a control group.

RESULTS

The sample included 57 effect sizes from 43 studies across 8 diagnostic categories. Significantly steeper discounting for individuals with a psychiatric disorder compared with controls was observed for major depressive disorder (Hedges g = 0.37; P = .002; k = 7), schizophrenia (Hedges g = 0.46; P = .004; k = 12), borderline personality disorder (Hedges g = 0.60; P < .001; k = 8), bipolar disorder (Hedges g = 0.68; P < .001; k = 4), bulimia nervosa (Hedges g = 0.41; P = .001; k = 4), and binge-eating disorder (Hedges g = 0.34; P = .001; k = 7). In contrast, anorexia nervosa exhibited statistically significantly shallower discounting (Hedges g = -0.30; P < .001; k = 10). Modest evidence of publication bias was indicated by a statistically significant Egger test for schizophrenia and at the aggregate level across studies.

CONCLUSIONS AND RELEVANCE

Results of this study appear to provide empirical support for delay discounting as a transdiagnostic process across most of the psychiatric disorders examined; the literature search also revealed limited studies in some disorders, notably posttraumatic stress disorder, which is a priority area for research.

The Neurobiology of Eating Disorders

Eating disorders are severe psychiatric illnesses with a typical age of onset in adolescence. Brain research in youth and young adults may help us identify specific neurobiology that contributes to onset and maintenance of those disorders. This article provides a state-of-the-art review of our current understanding of the neurobiology of anorexia nervosa and bulimia nervosa. This includes brain structure and function studies to understand food restriction, binge-eating or purging behaviors, cognitive and emotional factors, as well as interoception. Binge-eating disorder and avoidant restrictive food intake disorder are also discussed, but the literature is still very small.

Goal-directed vs. habitual instrumental behavior during reward processing in anorexia nervosa: an fMRI study

Previous studies have proposed that altered reward processing and elevated cognitive control underlie the etiology of anorexia nervosa (AN). A newly debated notion suggests altered habit learning and an overreliance on habits may contribute to the persistence of AN. In weight-recovered AN patients, we previously found neuroimaging-based evidence for unaltered reward processing, but elevated cognitive control. In order to differentiate between state versus trait factors, we here contrast the aforementioned hypotheses in a sample of acutely underweight AN (acAN) patients. 37 acAN patients and 37 closely matched healthy controls (HC) underwent a functional MRI while performing an established instrumental motivation task. We found no group differences with respect to neural responses during the anticipation or receipt of reward. However, the behavioral response data showed a bimodal distribution, indicative for a goal-directed (gAN) and a habit-driven (hAN) patient subgroup. Additional analyses revealed decreased mOFC activation during reward anticipation in hAN, which would be in line with a habit-driven response. These findings provide a new perspective on the debate regarding the notion of increased goal-directed versus habitual behavior in AN. If replicable, the observed dissociation between gAN and hAN might help to tailor therapeutic approaches to individual patient characteristics.

Cognitive Neuroscience of Eating Disorders

Anorexia nervosa and bulimia nervosa are characterized by severely restricted intake, binge eating, and compensatory behaviors like self-induced vomiting. The neurobiological underpinnings of these maladaptive behaviors are poorly understood, but the application of cognitive neuroscience and neuroimaging to eating disorders has begun to elucidate their pathophysiology. Specifically, this review focuses on 3 areas that suggest paths forward: reward, cognitive and behavioral control, and decision making. Understanding the brain-based mechanisms that promote and maintain these often chronic symptoms could guide the development of new and more effective treatments.

Can delay discounting deliver on the promise of RDoC?

The National Institute of Mental Health launched the Research Domain Criteria (RDoC) initiative to better understand dimensions of behavior and identify targets for treatment. Examining dimensions across psychiatric illnesses has proven challenging, as reliable behavioral paradigms that are known to engage specific neural circuits and translate across diagnostic populations are scarce. Delay discounting paradigms seem to be an exception: they are useful for understanding links between neural systems and behavior in healthy individuals, with potential for assessing how these mechanisms go awry in psychiatric illnesses. This article reviews relevant literature on delay discounting (or the rate at which the value of a reward decreases as the delay to receipt increases) in humans, including methods for examining it, its putative neural mechanisms, and its application in psychiatric research. There exist rigorous and reproducible paradigms to evaluate delay discounting, standard methods for calculating discount rate, and known neural systems probed by these paradigms. Abnormalities in discounting have been associated with psychopathology ranging from addiction (with steep discount rates indicating relative preference for immediate rewards) to anorexia nervosa (with shallow discount rates indicating preference for future rewards). The latest research suggests that delay discounting can be manipulated in the laboratory. Extensively studied in cognitive neuroscience, delay discounting assesses a dimension of behavior that is important for decision-making and is linked to neural substrates and to psychopathology. The question now is whether manipulating delay discounting can yield clinically significant changes in behavior that promote health. If so, then delay discounting could deliver on the RDoC promise.

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.

Increased delayed reward during intertemporal decision-making in schizophrenic patients and their unaffected siblings

Intertemporal choices are decisions with consequences in multiple time periods and constitute a significant part of social cognition. The shared neuropathological characteristics of patients with schizophrenia and their siblings might express intermediate phenotypes in behavior that could be used to further characterize the illness. Schizophrenic patients, unaffected siblings, and healthy controls underwent a computerized version of the "Intertemporal Choice Task". All participants could choose between sooner-smaller (SS) and later-larger (LL) options in now-trials and in not-now-trials. Subjects also underwent a battery of cognitive neuropsychological assessment. Our results indicated that schizophrenic patients and unaffected siblings both had a tendency to choose LL options in now-trials or not-now-trials compared to healthy controls. Schizophrenic patients had significantly lower scores in several cognitive tasks, including MoCA, attention, executive functions, and information processing when compared with the other two groups. Moreover, within the schizophrenic patient group, significant correlations were found between intertemporal decision-making performance and executive function. The present study showed that both schizophrenic patients and unaffected siblings preferred to choose larger-delayed rewards during intertemporal decision-making, which may result from frontal-striatal and frontal-parietal network dysfunction. Their intertemporal decision-making performance was associated with executive function performance.

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.

The Perception of Time Is Underestimated in Adolescents With Anorexia Nervosa

Research has revealed reduced temporal discounting (i.e., increased capacity to delay reward) and altered interoceptive awareness in anorexia nervosa (AN). In line with the research linking temporal underestimation with a reduced tendency to devalue a reward and reduced interoceptive awareness, we tested the hypothesis that time duration might be underestimated in AN. Our findings revealed that patients with AN displayed lower timing accuracy in the form of timing underestimation compared with controls. These results were not predicted by clinical, demographic factors, attention, and working memory performance of the participants. The evidence of a temporal underestimation bias in AN might be clinically relevant to explain their abnormal motivation in pursuing a long-term restrictive diet, in line with the evidence that increasing the subjective temporal proximity of remote future goals can boost motivation and the actual behavior to reach them.

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.

Processing and regulation of negative emotions in anorexia nervosa: An fMRI study

Theoretical models and recent advances in the treatment of anorexia nervosa (AN) have increasingly focused on the role of alterations in the processing and regulation of emotions. To date, however, our understanding of these changes is still limited and reports of emotional dysregulation in AN have been based largely on self-report data, and there is a relative lack of objective experimental evidence or neurobiological data. The current functional magnetic resonance imaging (fMRI) study investigated the hemodynamic correlates of passive viewing and voluntary downregulation of negative emotions by means of the reappraisal strategy detachment in AN patients. Detachment is regarded as adaptive regulation strategy associated with a reduction in emotion-related amygdala activity and increased recruitment of prefrontal brain regions associated with cognitive control processes. Emotion regulation efficacy was assessed via behavioral arousal ratings and fMRI activation elicited by an established experimental paradigm including negative images. Participants were instructed to either simply view emotional pictures or detach themselves from feelings triggered by the stimuli. The sample consisted of 36 predominantly adolescent female AN patients and a pairwise age-matched healthy control group. Behavioral and neuroimaging data analyses indicated a reduction of arousal and amygdala activity during the regulation condition for both patients and controls. However, compared with controls, individuals with AN showed increased activation in the amygdala as well as in the right dorsolateral prefrontal cortex (dlPFC) during the passive viewing of aversive compared with neutral pictures. These results extend previous findings indicative of altered processing of salient emotional stimuli in AN, but do not point to a general deficit in the voluntary regulation of negative emotions. Increased dlPFC activation in AN during passive viewing of negative stimuli is in line with the hypothesis that the disorder may be characterized by excessive self-control. Taken together, the data seem to suggest that reappraisal via detachment may be an effective strategy to reduce negative arousal for individuals with AN.

The Science Behind the Academy for Eating Disorders' Nine Truths About Eating Disorders

OBJECTIVE

In 2015, the Academy for Eating Disorders collaborated with international patient, advocacy, and parent organizations to craft the 'Nine Truths About Eating Disorders'. This document has been translated into over 30 languages and has been distributed globally to replace outdated and erroneous stereotypes about eating disorders with factual information. In this paper, we review the state of the science supporting the 'Nine Truths'.

METHODS

The literature supporting each of the 'Nine Truths' was reviewed, summarized and richly annotated.

RESULTS

Most of the 'Nine Truths' arise from well-established foundations in the scientific literature. Additional evidence is required to further substantiate some of the assertions in the document. Future investigations are needed in all areas to deepen our understanding of eating disorders, their causes and their treatments.

CONCLUSIONS

The 'Nine Truths About Eating Disorders' is a guiding document to accelerate global dissemination of accurate and evidence-informed information about eating disorders. Copyright © 2017 John Wiley & Sons, Ltd and Eating Disorders Association.

An adaptive, individualized fMRI delay discounting procedure to increase flexibility and optimize scanner time

Research on the rate at which people discount the value of future rewards has become increasingly prevalent as discount rate has been shown to be associated with many unhealthy patterns of behavior such as drug abuse, gambling, and overeating. fMRI research points to a fronto-parietal-limbic pathway that is active during decisions between smaller amounts of money now and larger amounts available after a delay. Researchers in this area have used different variants of delay discounting tasks and reported various contrasts between choice trials of different types from these tasks. For instance, researchers have compared 1) choices of delayed monetary amounts to choices of the immediate monetary amounts, 2) 'hard' choices made near one's point of indifference to 'easy' choices that require little thought, and 3) trials where an immediate choice is available versus trials where one is unavailable, regardless of actual eventual choice. These differences in procedure and analysis make comparison of results across studies difficult. In the present experiment, we designed a delay discounting task with the intended capability of being able to construct contrasts of all three comparisons listed above while optimizing scanning time to reduce costs and avoid participant fatigue. This was accomplished with an algorithm that customized the choice trials presented to each participant with the goal of equalizing choice trials of each type. We compared this task, which we refer to here as the individualized discounting task (IDT), to two other delay discounting tasks previously reported in the literature (McClure et al., 2004; Amlung et al., 2014) in 18 participants. Results show that the IDT can examine each of the three contrasts mentioned above, while yielding a similar degree of activation as the reference tasks. This suggests that this new task could be used in delay discounting fMRI studies to allow researchers to more easily compare their results to a majority of previous research while minimizing scanning duration.

Neural correlates of altered feedback learning in women recovered from anorexia nervosa

Anorexia nervosa (AN) is associated with exaggerated self-control and altered reward-based decision making, but the underlying neural mechanisms are poorly understood. Consistent with the notion of excessive cognitive control, we recently found increased dorsal anterior cingulate cortex (dACC) activation in acutely ill patients (acAN) on lose-shift trials in a probabilistic reversal learning (PRL) task. However, undernutrition may modulate brain function. In attempt to disentangle trait from state factors, the current fMRI study investigated cognitive control in recovered patients (recAN). Thirty-one recAN and 31 healthy controls (HC) completed a PRL task during fMRI. Based on previous findings, we focused on hemodynamic responses during lose-shift behaviour and conducted supplementary functional connectivity analysis. RecAN showed elevated lose-shift behaviour relative to HC. On the neural level, recAN showed normal dACC responses, but increased activation in fronto-parietal control regions. A trend for increased coupling between frontal and parietal regions of interest was also evident in recAN. The current findings in recAN differ from those in our previous study in acAN. While aberrant dACC response to negative feedback may be a correlate of the underweight state in acAN, impaired behavioural adaptation and elevated activation of cognitive control regions in recAN is suggestive of altered neural efficiency.

Temporal discounting across three psychiatric disorders: Anorexia nervosa, obsessive compulsive disorder, and social anxiety disorder

BACKGROUND

Temporal discounting refers to the tendency for rewards to lose value as the expected delay to receipt increases. Individuals with anorexia nervosa (AN) have been found to show reduced temporal discounting rates, indicating a greater preference for delayed rewards compared to healthy peers. Obsessive-compulsive disorder (OCD) and social anxiety disorder (SAD) commonly co-occur with AN, and anxiety has been related to development and prognosis of AN. We examined whether reduced temporal discounting is present across these potentially related disorders, and explored the relationship between temporal discounting and anxiety transdiagnostically.

METHODS

One hundred ninety six individuals (75 healthy controls (HC); 50 OCD; 27 AN; 44 SAD) completed two temporal discounting tasks in which they chose between smaller-sooner and larger-later monetary rewards. Two measures of discounting-discount rate and discount factor-were compared between diagnostic groups, and associations with anxious traits were examined.

RESULTS

Individuals with AN showed decreased temporal discounting compared to HC. OCD and SAD groups did not differ significantly from HC. Across the sample, anxiety was associated with decreased discounting; more anxious individuals showed a greater preference for delayed reward.

CONCLUSIONS

We replicated the findings that individuals with AN show an increased preference for delayed reward relative to HC and that individuals with OCD do not differ from HC. We also showed that individuals with SAD do not differ from HC in discounting. Across this large sample, two measures of anxious temperament were associated with temporal discounting. These data raise new questions about the relationship between this dimensional trait and psychopathology.

Increased anterior cingulate cortex response precedes behavioural adaptation in anorexia nervosa

Patients with anorexia nervosa (AN) are characterised by increased self-control, cognitive rigidity and impairments in set-shifting, but the underlying neural mechanisms are poorly understood. Here we used functional magnetic resonance imaging (fMRI) to elucidate the neural correlates of behavioural adaptation to changes in reward contingencies in young acutely ill AN patients. Thirty-six adolescent/young adult, non-chronic female AN patients and 36 age-matched healthy females completed a well-established probabilistic reversal learning task during fMRI. We analysed hemodynamic responses in empirically-defined regions of interest during positive feedback and negative feedback not followed/followed by behavioural adaptation and conducted functional connectivity analyses. Although overall task performance was comparable between groups, AN showed increased shifting after receiving negative feedback (lose-shift behaviour) and altered dorsal anterior cingulate cortex (dACC) responses as a function of feedback. Specifically, patients had increased dACC responses (which correlated with perfectionism) and task-related coupling with amygdala preceding behavioural adaption. Given the generally preserved task performance in young AN, elevated dACC responses specifically during behavioural adaption is suggestive of increased monitoring for the need to adjust performance strategies. Higher dACC-amygdala coupling and increased adaptation after negative feedback underlines this interpretation and could be related to intolerance of uncertainty which has been suggested for AN.