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

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Abstract

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.

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... Participants' diagnostic status (patients vs. healthy controls), the presence of safety behaviors in the situation (SB vs. no SB) and their interaction served as fixed effects. We used LMMs for the analysis of the present data as they are a powerful and flexible tool for analyzing repeated measures data [45,46] and have been successfully employed in other studies on fear and avoidance in eating disorders [47,48]. ...
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Fear of weight gain is a cardinal feature of eating disorders, including Anorexia Nervosa (AN). This fear motivates behaviors aimed at avoiding weight gain, such as restricting food intake. Of note, avoidance in AN is not confined to food-related items but extends to intense emotional states. Despite the presence of several forms of excessive avoidance in AN, little is known about the mechanisms underpinning avoidance behavior in AN. In the present exploratory study, we investigated whether university students with an elevated desire to avoid weight gain (as measured through self-reported Drive for Thinness, DT) show deficits in generic avoidance learning. Two-hundred and seventy-five female students filled in the Eating Disorder Inventory-II (EDI-II) and performed a food-unrelated avoidance task. Generalized and linear mixed models (GLMM) revealed that students scoring higher on the DT scale of the EDI-II showed more ineffective avoidance, suggesting a tendency for excessive avoidance in at-risk individuals for AN. Similar results might extend to other eating disorders.
Article
Background No consistent first-option psychological interventions for adult outpatients with anorexia nervosa emerges from guidelines. We aimed to compare stand-alone psychological interventions for adult outpatients with anorexia nervosa with a specific focus on body-mass index, eating disorder symptoms, and all-cause dropout rate. Methods In this systematic review and network meta-analysis, we assessed randomised controlled trials about stand-alone pharmacological or non-pharmacological treatments of adult outpatients with anorexia nervosa, defined according to standardised criteria, with data for at least two timepoints relating to either body-mass index or global eating disorder psychopathology. We searched Cochrane CENTRAL, CINAHL, MEDLINE, and PsychINFO for published and unpublished literature from inception until March 20, 2020. The primary outcomes were the change in body mass index and clinical symptoms, and the secondary outcome was all-cause dropout rate, which were all assessed for treatment as usual, cognitive behavioural therapy (CBT), Maudsley anorexia treatment for adults, family-based treatment, psychodynamic-oriented psychotherapies, a form of CBT targeting compulsive exercise, and cognitive remediation therapy followed by CBT. Global and local inconsistencies for the network meta-analysis were measured, and CINeMA was used to assess the confidence in evidence for primary outcomes. The protocol is registered in PROSPERO (CRD42017064429). Findings Of 14 003 studies assessed for their title and abstract, 16 (0·1%) randomised controlled trials for psychological treatments were included in the systematic review, of which 13 (0·1%) contributed to the network meta-analysis, with 1047 patients in total (of whom 1020 [97·4%] were female). None of the interventions outperformed treatment as usual in our primary outcomes, but the all-cause dropout rate was lower for CBT than for psychodynamic-oriented psychotherapies (OR 0·54, 95% CI 0·31–0·93). Heterogeneity or inconsistency emerged only for a few comparisons. Confidence in the evidence was low to very low. Interpretation Compared with treatment as usual, specific psychological treatments for adult outpatients with anorexia nervosa can be associated with modest improvements in terms of clinical course and quality of life, but no reliable evidence supports clear superiority or inferiority of the specific treatments that are recommended by clinical guidelines internationally. Our analysis is based on the best data from existing clinical studies, but these findings should not be seen as definitive or universally applicable. There is an urgent need to fund new research to develop and improve therapies for adults with anorexia nervosa. Meanwhile, to better understand the effects of available treatments, participant-level data should be made freely accessible to researchers to eventually identify whether specific subgroups of patients are more likely to respond to specific treatments. Funding Flinders University, National Institute for Health Research Oxford Health Biomedical Research Centre.
Article
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.
Article
Objective: Eating-related fear and anxiety are hallmark symptoms of eating disorders (EDs). However, it is still unclear which fears are most important (e.g., food, weight gain), which has practical implications, given treatments for eating-related fear necessitate modifications based on the specific fear driving ED pathology. For example, exposure treatments should be optimized based on specific fears that maintain pathology. The current study (N = 1,622 combined clinical ED and undergraduate sample) begins to answer questions on the precise nature of ED fears and how they operate with other ED symptoms. Method: We used network analysis to create two models of ED fears and symptoms. The first model consisted of ED fears only (e.g., fears of food, fears of weight gain) to identify which fear is most central. The second model consisted of ED fears and ED symptoms to detect how ED fears operate with ED symptoms. Results: We found fear of disliking how one's body feels due to weight gain, disliking eating in social situations, feeling tense around food, fear of judgment due to weight gain, and food anxiety were the most central ED fears. We also identified several bridge symptoms between ED fears and symptoms. Finally, we found that the most central ED fears predicted excessive exercise at two-month follow-up. Discussion: These data support the idea that consequences (i.e., judgment) associated with fears of weight gain and interoceptive fears are the most central ED fears. These data have implications for the future development of precision interventions targeted to address ED-related fear.
Article
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.
Article
The role of positive emotion in anorexia nervosa (AN) has been underappreciated in both theory and treatment. Yet, people with AN demonstrate high motivation for and sustained effort toward weight loss, achieving success to an extreme beyond the capability of most people. Positive emotion dysregulation may facilitate and reinforce such efforts. The positive emotion amplification (PE-AMP) model of AN describes a dynamic interplay between biologically based enhanced reward responding and cognitive-behavioral factors that amplify positive emotion, resulting in positive feedback cycles that motivate and reinforce weight loss behavior during the AN onset phase. These experiences subvert the pursuit of happiness by providing artificial senses of autonomy, competency, and relatedness to others (self-determination theory; Ryan & Deci, 2000) that provide a stark contrast to an otherwise negative emotional environment, resulting in the emergence and persistence of AN psychopathology as a self-sustaining sense of purpose. Ultimately, negative emotion, PE dysregulation, and artificial self-determination threats continue to drive AN behavior during the AN maintenance phase, pushing patients toward a genuine self-determination breakdown that can lead to hospitalization, health crises, relational strife and diminished quality of life, or even manifest in suicidal behavior. Future research directions and novel methodological approaches inspired by the PE-AMP model are discussed, as are important treatment implications for addressing this highly treatment-resistant disorder. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
Article
Findings of a few recent studies suggest that obesity is characterized by deficits in appetitive learning about food cues. This could point towards an increased tendency in obese individuals to overgeneralize appetitive responding to stimuli that resemble the conditioned food cue - possibly explaining frequent eating desires and overeating in obesity. The current study aimed to investigate whether obese individuals 1) indeed exhibit appetitive learning deficits and 2) show overgeneralization of conditioned appetitive responses. Obese and matched healthy-weight females (N = 85) completed a differential appetitive conditioning task using food as rewards. First, appetitive responding to a novel stimulus was learned (acquisition phase), after which stimuli with varying resemblance to the food-associated stimulus were presented (generalization phase). Cue-elicited eating expectancies, eating desires, stimulus evaluations, and actual food intake were examined. Results indicated successful acquisition of appetitive responding across all outcome measures. The acquired responses also generalized, indicating that generalization can function as an additional mechanism by which learned food cues can promote food consumption. The data further suggested that overweight and obesity are not characterized by appetitive learning deficits nor by overgeneralization, but that a subgroup of obese individuals (those high in trait anxiety) may be more prone to overgeneralization of appetitive responding.
Article
Objective Anorexia nervosa is characterized by severe malnutrition. This study tested the hypothesis that fear of food is a learned behaviour and evaluated the feasibility and effectiveness of gradual exposure to food to improve eating behaviour in people with anorexia nervosa. Methods Eighteen women were recruited and completed baseline self‐reports. They were interviewed regarding early experiences of eating and the development of food‐related anxiety. Participants received eight sessions of in vivo food exposure. Results Findings indicated that fear of food is a learned behaviour, associated with catastrophic thoughts around the consequences of eating and safety behaviours. Patients consumed at least half of the food item selected in all but one session. Body mass index increased, and food restriction, eating concern, eating disorder‐related preoccupations, and overall anxiety reduced (medium/large ES). Conclusion Findings corroborate an anxiety‐based model of anorexia nervosa and support the relevance of targeting food‐related fears using exposure‐based protocols.
Article
Pervasive avoidance behaviour is a core feature of anxiety disorders. However, little is known about how the availability of avoidance modulates learned threat responding. To assess this question, we recorded avoidance behaviour, electrodermal activity and expectancy ratings in 53 healthy participants during an associative learning paradigm with embedded unavoidable and avoidable trials. When avoidance was available, we observed greater avoidance behaviour for threat versus safety cues, as well as reduced differential skin conductance responses for unavoidable threat versus safety cues. When avoidance was unavailable, as during the extinction phase, we observed sustained differential skin conductance responses for threat versus safety cues. For all phases, we found greater expectancy ratings for threat versus safe cues. Furthermore, greater avoidance behaviour predicted larger differential skin conductance responses to threat versus safety cues during extinction. Overall, the results show that the conditioned response is attenuated during situations where avoidance is available, but it recovers when avoidance is unavailable, subsequently prolonging threat extinction.
Article
Over the past decade, mouse tracking in choice tasks has become a popular method across psychological science. This method exploits hand movements as a measure of multiple response activations that can be tracked continuously over hundreds of milliseconds. Whereas early mouse-tracking research focused on specific debates, researchers have realized that the methodology has far broader theoretical value. This more recent work demonstrates that mouse tracking is a widely applicable measure across the field, capable of exposing the microstructure of real-time decisions, including their component processes and millisecond-resolution time course, in ways that inform theory. In this article, recent advances in the mouse-tracking approach are described, and comparisons with the gold standard measure of reaction time and other temporally sensitive methodologies are provided. Future directions, including mapping to neural representations with brain imaging and ways to improve our theoretical understanding of mouse-tracking methodology, are discussed.
Article
Background. To determine the impact of specialized treatments, relative to comparator treatments, upon the weight and psychological symptoms of anorexia nervosa (AN) at end-of-treatment (EOT) and follow-up. Methods. Randomized controlled trials (RCTs) between January 1980 and December 2017 that reported the effects of at least two treatments on AN were screened. Weight and psychological symptoms were analyzed separately for each study. PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were followed, and studies were assessed using the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) criteria and Cochrane risk of bias tool. Results. We identified 35 eligible RCTs, comprising data from 2524 patients. Meta-analyses revealed a significant treatment effect on weight outcomes at EOT [g = 0.16, 95% CI (0.05– 0.28), p = 0.006], but not at follow-up [g = 0.11, 95% CI (−0.04 to 0.27), p = 0.15]. There was no significant treatment effect on psychological outcomes at either EOT [g = −0.03, 95% CI (−0.14 to 0.08), p = 0.63], or follow-up [g = −0.001, 95% CI (−0.11 to 0.11), p = 0.98]. There was no strong evidence of publication bias or significant moderator effects for illness duration, mean age, year of publication, comparator group category, or risk of bias (all p values > 0.05). Conclusions. Current specialized treatments are more adept than comparator interventions at imparting change in weight-based AN symptoms at EOT, but not at follow-up. Specialized treatments confer no advantage over comparator interventions in terms of psychological symptoms. Future precision treatment efforts require a specific focus on the psychological symptoms of AN.
Article
Background and Objectives The reduction of avoidance behavior is a central target in the treatment of anxiety disorders, but it has rarely been studied how approach of fear-relevant stimuli may be initiated. In two studies, the impact of hypothetical monetary and symbolic social incentives on approach-avoidance behavior was examined. Methods In Study 1, individuals high or low on fear of spiders (N = 84) could choose to approach a fear-relevant versus a neutral stimulus, which were equally rewarded. During a subsequent micro-intervention, approach of the fear-relevant stimulus was differentially rewarded either by monetary or social incentives. In Study 2 (N = 76), initial incentives for approach were discontinued in the second phase to investigate the stability of approach. Results Results indicated that hypothetical monetary and symbolic social incentives reduced or eliminated initial avoidance, even in highly fearful individuals. Approach resulted in a decrease of self-reported aversiveness towards the fear-relevant stimulus. However, even after successful approach, fearful individuals showed significant avoidance behavior when incentives for approach were discontinued. Limitations Future research should investigate the long-term effects of prolonged approach incentives on multiple levels of fear (e.g., self-report, behavioral, physiological). It should also be tested if such an intervention actually improves compliance with exposure based interventions. Conclusions The present findings highlight that incentives are useful to initiate initial approach towards a feared stimulus. Although incentive-based approach may neither fully eliminate avoidance nor negative feelings towards the feared stimulus, such operant interventions may set the stage for more extensive extinction training.
Article
Clinical and preclinical findings suggest that individuals with abnormal responses to reward cues (stimuli associated with reward) may be at risk for maladaptive behaviors including obesity, addiction and depression. Our objective was to develop a new paradigm for producing appetitive conditioning using primary (food) rewards in humans, and investigate the equivalency of several outcomes previously used to measure appetitive responses to conditioned cues. We used an individualized food reward, and multimodal subjective, psychophysiological and behavioral measures of appetitive responses to a conditioned stimulus (CS) that predicted delivery of that food. We tested convergence among these measures of appetitive response, and relationships between these measures and action impulsivity, a putative correlate of appetitive conditioning. 90 healthy young adults participated. Although the paradigm produced robust appetitive conditioning in some measures, particularly psychophysiological ones, there were not strong correlations among measures of appetitive responses to the CS, as would be expected if they indexed a single underlying process. In addition, there was only one measure that related to impulsivity. These results provide important information for translational researchers interested in appetitive conditioning, suggesting that various measures of appetitive conditioning cannot be treated interchangeably.
Article
Functional magnetic resonance imaging (fMRI) studies have displayed a dysregulation in the way in which the brain processes pleasant taste stimuli in patients with anorexia nervosa (AN) and bulimia nervosa (BN). However, exactly how the brain processes disgusting basic taste stimuli has never been investigated, even though disgust plays a role in food intake modulation and AN and BN patients exhibit high disgust sensitivity. Therefore, we investigated the activation of brain areas following the administration of pleasant and aversive basic taste stimuli in symptomatic AN and BN patients compared to healthy subjects. Twenty underweight AN women, 20 symptomatic BN women and 20 healthy women underwent fMRI while tasting 0.292 M sucrose solution (sweet taste), 0.5 mM quinine hydrochloride solution (bitter taste) and water as a reference taste. In symptomatic AN and BN patients the pleasant sweet stimulus induced a higher activation in several brain areas than that induced by the aversive bitter taste. The opposite occurred in healthy controls. Moreover, compared to healthy controls, AN patients showed a decreased response to the bitter stimulus in the right amygdala and left anterior cingulate cortex, while BN patients showed a decreased response to the bitter stimulus in the right amygdala and left insula. These results show an altered processing of rewarding and aversive taste stimuli in ED patients, which may be relevant for understanding the pathophysiology of AN and BN.
Article
Anorexia nervosa (AN) is uniquely placed in the spectrum of psychiatric nosology as the only disorder in which an actualization of the core symptomatic fear (ie, weight gain) is directly targeted as a primary treatment goal. While treatment outcomes are generally indexed along dimensions of both weight-based and cognitive symp-tomatology, the initial focus on immediate weight restoration raises an important question relating to how the fear of weight gain might be abated throughout treatment when this primary symptomatic fear (ie, weight gain) is targeted and confirmed. Here, we address an important gulf between extinction theory and the practice of exposure therapy for AN. Recent fear extinction literature posits that the ame-lioration of acquired fear does not operate solely according to habituation processes, such that exposure to feared stimuli alone is insufficient in ensuring long-term fear reduction. 1 Rather, fear reduction more centrally operates via mechanisms of inhibitory learning, which is an active learning process in which the violation of expected feared outcomes results in the new learning of nonthreat associations relating to the originally feared stimulus, which in turn serves to inhibit anxiety 1 (Figure). As such, exposure therapies are now tailored toward maximally violating fear expectancies, rather than aiming for habituation, per se, with long-term consolidation of fear extinction being centrally linked to treatment outcome. 2 However, this theoretical framework is predicated on the clear distinction drawn between feared cues/ stimuli and feared outcomes, which, in turn, may be violated throughout treatment to generate inhibitory learning. 1 This is particularly relevant in the context of AN, for which, despite the inherent centrality of exposure processes, sparse empirical evidence has precisely deconstructed core fear associations, which may nullify the most salient pathway of fear extinction.
Article
In this study, we aimed to examine the psychological experience over the course of an inpatient treatment implementing rapid-refeeding protocol for adolescent patients with anorexia nervosa (AN). Ten female participants were included in the study and interviews were conducted on a weekly basis over the course of their admissions. Interviews were audio-recorded and analysed according to the principles of thematic analysis. Results revealed a multidimensional process broadly implicating three phases of treatment; reconciling with the ‘AN’ diagnosis, adjustment to treatment, and reflection and integration. Overall, these phases demonstrated a complex and often ambivalent psychological process whereby acceptance for physical and medical interventions was often in conflict with individuals’ affective experiences. Clinical implications of these findings are discussed and avenues for future research highlighted.
Article
Objective: To report on long-term mortality in anorexia nervosa (AN), bulimia nervosa (BN), binge eating disorder (BED), and eating disorder not otherwise specified (ED-NOS), causes of death, and predictors of early death. Method: A large sample of consecutively admitted inpatients (N = 5,839) was followed-up on vital status through the German civil registry office. Of these patients 1,639 were treated for AN, 1,930 for BN, 363 for BED, and 1,907 for ED-NOS. Data from the main inpatient hospital treatment were applied to bivariate and multivariate Cox regression analyses on survival time from onset of eating disorder to death or end of observation. Standardized mortality ratios (SMR) were computed matched for age, gender, and person-years. Results: SMR were 5.35 for AN, 1.49 for BN, 1.50 for BED, 2.39 for narrowly defined ED-NOS, and 1.70 for widely defined ED-NOS. Patients with AN died earlier than patients with BN, BED, or ED-NOS who did not differ. A diagnosis of AN, chronicity, later age of onset, not living in a relationship, and an irregular type of discharge from index inpatient treatment were major predictors of a shorter time to death. Suicidality was a univariate predictor of a shorter time to death in BN only. AN patients mostly died from natural causes related to their eating disorder. Discussion: Mortality in AN is excessive and considerably higher than in BN, BED, and ED-NOS. © 2015 Wiley Periodicals, Inc. (Int J Eat Disord 2015).
Article
Anorexia nervosa is characterized by chronic food avoidance that is resistant to change. Disgust conditioning offers one potential unexplored mechanism for explaining this behavioral disturbance because of its specific role in facilitating food avoidance in adaptive situations. A food based reversal learning paradigm was used to study response flexibility in 14 adolescent females with restricting subtype anorexia nervosa (AN-R) and 15 healthy control (HC) participants. Expectancy ratings were coded as a behavioral measure of flexibility and electromyography recordings from the levator labii (disgust), zygomaticus major (pleasure), and corrugator (general negative affect) provided psychophysiological measures of emotion. Response inflexibility was higher for participants with AN-R, as evidenced by lower extinction and updated expectancy ratings during reversal. EMG responses to food stimuli were predictive of both extinction and new learning. Among AN-R patients, disgust specific responses to food were associated with impaired extinction, as were elevated pleasure responses to the cued absence of food. Disgust conditioning appears to influence food learning in acutely ill patients with AN-R and may be maintained by counter-regulatory acquisition of a pleasure response to food avoidance and an aversive response to food presence. Developing strategies to target disgust may improve existing interventions for patients with AN. Copyright © 2015 Elsevier Ltd. All rights reserved.