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Can you learn to starve yourself? Inducing food avoidance in the laboratory
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.
... Accordingly, we tested whether healthy women with increased levels of anorexia nervosa symptoms and characteristics show learning abnormalities related to the acquisition and extinction of food avoidance behaviors. Data from a previous experiment (Spix, Schutzeichel, et al., 2023) was used and supplemented with new questionnaire data. Based on participants' levels of anorexia nervosa symptoms and characteristics, we subtyped an analogue and a healthy group and compared their performance on a food avoidance learning task. ...
... During classical conditioning, food and eating-related stimuli (conditioned stimuli; CSs) become associated with an aversive outcome (unconditioned stimulus; US), such as (uncontrollable) weight gain, social judgment, or gastrointestinal malaise (Levinson et al., 2019;Levinson & Williams, 2020;. Consequently, food and eating-related stimuli start to trigger aversive conditioned responses (CRs), such as heightened autonomic arousal, fear and/or disgust, and avoidance tendencies (Hildebrandt et al., 2015;Melles et al., 2021;Spix, Schutzeichel, et al., 2023). During operant conditioning, individuals learn about the consequences of their avoidance behaviors (Krypotos et al., 2015;LeDoux et al., 2017): if food restriction leads to the omission of the expected aversive outcome and/or reduces anxiety and disgust, individuals are more likely to avoid food intake again in the future (negative reinforcement;De Houwer & Hughes, 2020). ...
... Additionally, food avoidance can be reinforced by its pleasant consequences, such as weight loss, compliments by others, or elevated feelings of control and self-esteem (Marzola et al., 2015;Selby & Coniglio, 2020;Walsh, 2013). In line with this model, we showed in a previous study that healthy women can acquire persistent food avoidance behaviors via classical and operant conditioning (Spix, Schutzeichel, et al., 2023). ...
Previous research has shown that food avoidance can be learned via classical and operant conditioning. This leads to the question of whether learning deficits could contribute to the harmful food avoidance seen in individuals with anorexia nervosa. Accordingly, we tested whether healthy women with increased levels of anorexia nervosa symptoms and characteristics show learning abnormalities related to the acquisition and extinction of food avoidance behaviors. Data from a previous experiment (Spix, Schutzeichel, et al., 2023) was used and supplemented with new questionnaire data. Based on participants' levels of anorexia nervosa symptoms and characteristics, we subtyped an analogue and a healthy group and compared their performance on a food avoidance learning task. We assessed the frequency of avoidance responses, as well as relief, frustration, eating desires, fear, and liking for the conditioned stimulus (CS) associated with food intake. The analogue group showed more unnecessary food avoidance behaviors, a greater relief about the omission of the food, and a faster and more persistent reduction in eating desires than the healthy group. There were no differences between groups in frustration, fear, and liking. Learning abnormalities might contribute to the development and maintenance of food avoidance in individuals with anorexia nervosa.
... 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]. ...
When evaluating ambiguous situations, humans sometimes use their behavior as a source of information (behavior-as-information effect) and interpret safety behaviors as evidence for danger. Accordingly, we hypothesized that eating disorder safety behaviors (restrictive eating, body checking, etc.) might aggravate fear and anxiety in individuals with an eating disorder. The present study tested to what extent eating disorder safety behaviors increase threat perception in individuals with and without an eating disorder. For this, 108 individuals with a self-reported eating disorder diagnosis and 82 healthy controls rated the dangerousness of several short situations. The situations systematically varied in the presence of eating disorder safety behaviors and danger information. As expected, all participants perceived situations in which the protagonist executed an eating disorder safety behavior as more threatening than situations without a safety behavior. This ‘behavior-as-information’ effect was equally strong in individuals with and without an eating disorder. Additionally, safety behaviors strengthened threat perception more in safe situations than in dangerous situations. To conclude, the presence of eating disorder safety behavior can increase threat perception regardless of whether individuals have an eating disorder or not. This makes eating disorder safety behaviors a potential risk factor for the development and maintenance of eating disorder fears.
Background
Fears and avoidance behaviors are common symptoms of eating disorders. It was investigated whether different eating disorder diagnoses are equally characterized by similar fears and avoidance behaviors.
Methods
Individuals with self-reported eating disorders (n = 250) and healthy controls (n = 95) completed online questionnaires assessing general fears, eating related fears, and avoidance behaviors.
Results
All self-reported eating disorder diagnoses showed more eating related fears, general fears, and avoidance behaviors than healthy controls. Individuals with binge eating disorder showed less specific and general fears on some but by no means all scales, yet they showed less food avoidance behaviors than all other eating disorders and less eating restraint than anorexia nervosa and bulimia nervosa.
Conclusions
Eating related fears, general fears, and food avoidance behaviors were found to be transdiagnostic symptoms in self-reported eating disorders. Individuals with binge eating disorder also exhibit more fears and avoidance behaviors than healthy controls, but to a lesser extent than the other eating disorders. Specialized interventions targeting fears and avoidance may be promising add-on interventions not only in the treatment of anorexia nervosa, but in the treatment of all eating disorders.
Movement tracking is a novel process tracing method promising unique access to the temporal dynamics of cognitive processes. The method involves high-resolution tracking of the hand or handheld devices, e.g., a computer mouse, while they are used to make a choice. In contrast to other process tracing methods, which mostly focus on information acquisition, movement tracking focuses on the processes of information integration and preference formation. In this article, we present a tutorial to movement tracking of cognitive processes with the mousetrap R package. We will address all steps of the research process from design to interpretation, with a particular focus on data processing and analysis. Using a representative working example, we will demonstrate how the various steps of movement tracking analysis can be implemented with mousetrap and provide thorough explanations on their theoretical background and interpretation. Finally, we present a list of recommendations to assist researchers in addressing their own research question using movement tracking of cognitive processes.
Anorexia Nervosa is a severe and disabling mental disorder and a huge challenge to treat. Intense fears of e.g., food, eating, weight gain and social evaluation are core features of anorexia nervosa and obstacles during treatment. The perceived threats trigger avoidance and safety behaviors like highly restrictive eating, strict eating rules, vomiting and body checking, to minimize feared outcomes. The role of avoidance in anorexia nervosa is however hardly studied experimentally. In the present article, the focus is on a new transdiagnostic research agenda featuring both basic and clinical experimental research into avoidance as a most important mechanism maintaining the eating disorder. Avoidance learning and the generalization of learned avoidance behaviors are discussed, as well as safety behaviors and the need for inhibitory learning as a treatment target during exposure therapy.
Mixed-effects models are a powerful tool for modeling fixed and random effects simultaneously, but do not offer a feasible analytic solution for estimating the probability that a test correctly rejects the null hypothesis. Being able to estimate this probability, however, is critical for sample size planning, as power is closely linked to the reliability and replicability of empirical findings. A flexible and very intuitive alternative to analytic power solutions are simulation-based power analyses. Although various tools for conducting simulation-based power analyses for mixed-effects models are available, there is lack of guidance on how to appropriately use them. In this tutorial, we discuss how to estimate power for mixed-effects models in different use cases: first, how to use models that were fit on available (e.g. published) data to determine sample size; second, how to determine the number of stimuli required for sufficient power; and finally, how to conduct sample size planning without available data. Our examples cover both linear and generalized linear models and we provide code and resources for performing simulation-based power analyses on openly accessible data sets. The present work therefore helps researchers to navigate sound research design when using mixed-effects models, by summarizing resources, collating available knowledge, providing solutions and tools, and applying them to real-world problems in sample sizing planning when sophisticated analysis procedures like mixed-effects models are outlined as inferential procedures.
Avoidance is a transdiagnostic symptom of clinical anxiety and its reduction a major focus of cognitive-behavioral treatments. This study examined the instrumental extinction of goal-directed avoidance by means of incentives, verbal instruction, and social observation and their influence on fear extinction. Participants acquired conditioned fear and instrumental avoidance responses (N = 160). In four randomized groups, the reduction of avoidance by incentives for non-avoidance, instructions to refrain from avoidance, and social observation of non-avoidance was compared to no intervention before removing the aversive outcome. Conditioned fear when avoidance became unavailable subsequently was tested. Incentives, instruction, and observation all reduced avoidance better than no intervention, however, with different degrees and influence on conditioned fear. Incentives and instructions strongly reduced avoidance despite high levels of fear (i.e., fear-opposite actions). This initiated fear extinction, thereby reducing conditioned fear when avoidance became unavailable. Social observation directly reduced conditioned fear, presumably because it conveyed additional information about the absence of the aversive outcome. However, observation only moderately reduced avoidance and resulted in higher fear when avoidance became unavailable. The effects of social observation may depend on the nuances of the demonstrator's behavior. The clear effects of incentive and instructions provide support for clinical interventions to reduce avoidance during exposure therapy and can serve as experimental models for their controlled investigation.
In both theoretical and applied research, it is often of interest to assess the strength of an observed association. This is typically done to allow the judgment of the magnitude of an effect (especially when units of measurement are not meaningful, e.g., in the use of estimated latent variables; Bollen, 1989), to facilitate comparing between predictors' importance within a given model, or both. Though some indices of effect size, such as the correlation coefficient (itself a standardized covariance coefficient) are readily available, other measures are often harder to obtain. effectsize is an R package (R Core Team, 2020) that fills this important gap, providing utilities for easily estimating a wide variety of standardized effect sizes (i.e., effect sizes that are not tied to the units of measurement of the variables of interest) and their confidence intervals (CIs), from a variety of statistical models. effectsize provides easy-to-use functions, with full documentation and explanation of the various effect sizes offered, and is also used by developers of other R packages as the back-end for effect size computation, such as parameters (Lüdecke et al., 2020), ggstatsplot (Patil, 2018), gtsummary (Sjoberg et al., 2020) and more. Comparison to Other Packages effectsize's functionality is in part comparable to packages like lm.beta (Behrendt, 2014), MOTE (Buchanan et al., 2019), and MBESS (K. Kelley, 2020). Yet, there are some notable differences, e.g.: • lm.beta provides standardized regression coefficients for linear models, based on post-hoc model matrix standardization. However, the functionality is available only for a limited number of models (models inheriting from the lm class), whereas effectsize provides support for many types of models, including (generalized) linear mixed models, Bayesian models, and more. Additionally, in additional to post-hoc model matrix standardization, effectsize offers other methods of standardization (see below). • Both MOTE and MBESS provide functions for computing effect sizes such as Cohen's d and effect sizes for ANOVAs (Cohen, 1988), and their confidence intervals. However, both require manual input of For t-statistics, degrees of freedom, and sums of squares for the computation the effect sizes, whereas effectsize can automatically extract this information from the provided models, thus allowing for better ease-of-use as well as reducing any potential for error.
Open access pdf of book (free) available at: www.psychologyoflearning.be xxxxxxxxxxxxxx
Paper copies for sale at https://mitpress.mit.edu/books/psychology-learning xxxxxxxxxxxxxxx
Book synopsis xxxxxxxxxxxxxx
Learning unites all living creatures, from simple microbes to complex human beings. But what exactly is learning? And how does it work? For over a century now, psychologists have asked and answered such questions. Some (like behavior analysts) examined the way in which the environment shapes behavior whereas others (like cognitive scientists) have sought to understand the mental processes that enable us to learn. Our book offers an introduction to the psychology of learning that draws on the key findings and major insights from both functional (e.g., behavior analysis) and cognitive approaches. We first provide an in depth discussion of the nature of learning and the way it is studied in psychology. We then review research showing how seemingly simple regularities in the environment lead to powerful changes in behavior, from habituation, and classical conditioning, to operant conditioning effects. Moving beyond the known literature, we introduce the concept of complex learning and consider the idea that, in verbal human beings, even seemingly simple types of learning might qualify as instances of complex learning. Finally, we offer many examples of how psychological research on learning is being used to promote human well-being and alleviate societal problems such as psychological suffering and climate change.
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.
Human fear conditioning research since Watson's case study on "Little Albert" has vastly evolved and its impact today is reaching far beyond phobic anxiety. This review focuses on how fear conditioning research, mainly using exteroceptive conditioned stimuli (CSs) and aversive, non-noxious stimuli as unconditioned stimuli (USs), has been extended and translated to chronic pain research. We describe the different pain-related fear conditioning paradigms using proprioceptive and interoceptive CSs and painful stimuli as USs that have been developed to study specific forms of pain-related fear (i.e. fear of movement, fear of touch, fear of visceral sensations, and fear of penetration) that are relevant for different chronic pain conditions (i.e. musculoskeletal pain, neuropathic pain, visceral pain, and genital pain). We present evidence that patients with chronic pain demonstrate impaired safety learning and excessive fear generalization; learning anomalies that have also been observed in anxiety disorders. Extinction-based protocols (exposure in vivo) have been developed to reduce pain-related fear and increase daily functioning in various chronic pain disorders. Finally, we outline some challenges and future directions to further our understanding of learning mechanisms underlying the development, persistence, and treatment of chronic pain disability.
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).
Fear motivates different types of defensive behaviors. These behaviors are, however, not merely byproducts of fear. In this review, we highlight a bi-directional relationship between conditioned fear and instrumental defensive behavior in humans. We discuss mechanisms involved in the link from fear to goal-directed avoidance (e.g., relief,
generalization), that may become habitual. These defensive behaviors may in turn reduce, preserve, or amplify fear responding (e.g., protection-from-extinction, behavior-asinformation). Multiple factors moderate this bi-directional relationship. Evidence for amplifying and dampening effects of inter-individual differences (e.g., trait anxiety, distress tolerance), intra-individual states (e.g., stress), and external factors (e.g., incentives for competing behavior) on goal-directed and/or habitual avoidance is reviewed. However, the exact mechanisms by which these factors moderate the bi-directional relationship between fear and instrumental defensive behavior are still largely unknown (e.g., modulating avoidance directly vs. indirectly via conditioned fear). Finally, we discuss major implications: First, understanding factors moderating the bi-directional relationship provides insights into risk and resilience factors for anxious psychopathology. Second, specific experimental models and clinical interventions can be mapped onto distinct defensive behaviors (e.g.,
goal-directed vs. habitual avoidance). More precise matching will help to develop nuanced models and interventions to reduce pathological behaviors and individualize treatments.
Background and objectives
When avoiding threat conflicts with approaching rewards, balanced responses to threat and reward information is required to guide functional behavior. Elevated threat avoidance characterizes anxious psychopathology. However, little is known about the mutual impact of threat and reward information on approach-avoidance behavior and its link to anxiety.
Methods
High trait-anxious and low-anxious individuals (N = 74) repeatedly choose between two options. A threat/high-reward option was linked to two outcomes: a varying chance to receive an aversive stimulus and a varying high reward. A safe/low-reward option was linked to absence of the aversive stimulus and a low reward.
Results
Avoidance of the threat/high-reward option increased with increasing threat. Despite threat, low-anxious individuals increasingly approach the threat/high-reward option when rewards increased. High-compared to low-anxious individuals showed elevated avoidance, but only in the presence of high competing rewards.
Limitations
Future research should examine boundary conditions by manipulating type and motivational value of appetitive and aversive outcomes (e.g., food as primary reinforcer, real money).
Conclusions
These findings suggest that a weaker impact of rewards competing with threat during approach-avoidance behavior contributes to elevated threat avoidance in anxious psychopathology. Costly avoidance may thus be a factor involved in anxious psychopathology.
Maladaptive safety behavior maintains fear and anxiety by prohibiting inhibitory learning about the non-occurrence of feared outcomes (known as protection from extinction). Not engaging in safety behavior, however, requires to act opposite to fear-motivated behavioral tendencies. The initiation of such fear-opposite action by positive outcomes, which were in conflict with safety behavior, was tested. Following fear acquisition to a warning signal (CS+), participants acquired safety behavior to prevent the aversive outcome (n = 48). Next, safety behavior also prevented gaining rewards. In a control group (n=50), neutral outcomes were presented to control for novelty effects of the second outcome. Subsequently, no aversive outcome occurred anymore. Phases with safety behavior were intermitted by phases without safety behavior being available to examine cognitive and physiological indicators of fear and anxiety. Without competing positive outcomes, safety behavior was frequently executed, persisted in absence of the aversive outcome, and prohibited extinction learning. Positive outcomes clearly reduced safety behavior despite equal levels of acquired fear. This enabled fear extinction as soon as the aversive outcome was absent. Importantly, this extinction learning resulted in attenuated fear and anxiety responses when safety behavior became unavailable. Post-hoc findings indicated that the mere anticipation of positive outcomes slightly reduced safety behavior. Thus, competing positive outcomes triggered fear-opposite action that prevented persistent safety behavior and protection from extinction.
The terms food avoidance and food aversion are often used interchangeably in the eating disorders (EDs) literature. However, they represent two different (but closely related) constructs that are the result of different processes. In patients suffering from anorexia nervosa, bulimia nervosa and avoidant/restrictive food intake disorder, food avoidance/restriction is usually assumed to be motivated by fear/anxiety (e.g., “intense fear of gaining weight or becoming fat” or “being afraid to eat after a frightening episode of choking”). In contrast, studies show that taste-aversion often leads to food avoidance. Unlike fear-motivated avoidance in which the flavour of food becomes a signal for danger, avoidance produced by taste aversions involves a reduction in the amount consumed due to a hedonic downshift. Here the attractiveness of the flavour changes by its association with a nauseogenic event. It is noteworthy that both sources of food avoidance exhibit different behavioural characteristics, contents of learning, and activate different brain regions and neuromodulators. This is especially important for the understanding and treatment of the EDs and their most serious behavioural manifestation: the life-threatening food refusal. Finally, the clinical implications of such a distinction and promising future research directions are discussed.
Rewards for approaching a feared stimulus may compete with fear reduction inherent to avoidance and thereby alter fear and avoidance learning. However, the impact of such competing rewards on fear and avoidance acquisition has not been investigated. During acquisition, participants chose between one option (CS + option) associated with a neutral stimulus followed by an aversive unconditioned stimulus (US) and another option (CS option) associated with another neutral stimulus followed by no US (N = 223 randomized into three groups). In a subsequent test, no more USs occurred. In one group, competing rewards were established by linking the CS + option to high rewards and the CS option to low rewards during acquisition and test (Reward Group). In a second group, rewards were present during acquisition, but discontinued during test (Initial-Reward Group). In a third group, rewards were completely absent (No-Reward Group). Without competing rewards, significant avoidance was acquired and persisted in the absence of the US. Competing rewards attenuated avoidance acquisition already after the first experience of the aversive US. Avoidance remained attenuated even when rewards were discontinued during test. Rewards did, however, not change the level of fear responses to the CS+ (US expectancy, skin conductance). Finally, rewards did not change the level of fear reduction during test, which was, however, experienced earlier. Summarized, rewards for approaching aversive events do not buffer fear acquisition, but can prevent avoidance. This damping of avoidance may initiate fear extinction.
Excessive avoidance towards innocuous cues is a central diagnostic criterion across anxiety-related disorders. Relevant laboratory paradigms typically include instrumental learning procedures, where the presentation of an aversive cue (e.g., a shock) can be prevented by executing an experimenter-defined response (e.g., a button press) during the presentation of a warning cue (e.g., a square). Despite the popularity of these paradigms, there is no evaluation of how well the experimental findings of conditioned avoidance extend to maladaptive avoidance, or whether findings from animal studies could be informative for human studies. Here, we present a validation of the conditioned avoidance paradigm. We show that although this procedure meets the majority of the tested validity criteria (i.e. face, construct, predictive, and diagnostic validity), it also faces a number of challenges, including the non-consideration of individual differences in learning or the use of procedures that cannot be easily translated to clinical settings. For meeting these challenges, we suggest extensions of the paradigm including the test of individual differences by using ambiguous stimuli as well as the use of virtual reality procedures. Our main conclusion is that despite the significant knowledge provided in conditioned avoidance paradigms, their expansion will allow reaching more theoretical and clinical insights.
In psychology, attempts to replicate published findings are less successful than expected. For properly powered studies replication rate should be around 80%, whereas in practice less than 40% of the studies selected from different areas of psychology can be replicated. Researchers in cognitive psychology are hindered in estimating the power of their studies, because the designs they use present a sample of stimulus materials to a sample of participants, a situation not covered by most power formulas. To remedy the situation, we review the literature related to the topic and introduce recent software packages, which we apply to the data of two masked priming studies with high power. We checked how we could estimate the power of each study and how much they could be reduced to remain powerful enough. On the basis of this analysis, we recommend that a properly powered reaction time experiment with repeated measures has at least 1,600 word observations per condition (e.g., 40 participants, 40 stimuli). This is considerably more than current practice. We also show that researchers must include the number of observations in meta-analyses because the effect sizes currently reported depend on the number of stimuli presented to the participants. Our analyses can easily be applied to new datasets gathered.
We conducted a human fear conditioning experiment in which three different color cues were followed by an aversive electric shock on 0, 50, and 100% of the trials, and thus induced low (L), partial (P), and high (H) shock expectancy, respectively. The cues differed with respect to the strength of their shock association (L < P < H) and the uncertainty of their prediction (L < P > H). During conditioning we measured pupil dilation and ocular fixations to index differences in the attentional processing of the cues. After conditioning, the shock-associated colors were introduced as irrelevant distracters during visual search for a shape target while shocks were no longer administered and we analyzed the cues’ potential to capture and hold overt attention automatically. Our findings suggest that fear conditioning creates an automatic attention bias for the conditioned cues that depends on their correlation with the aversive outcome. This bias was exclusively linked to the strength of the cues’ shock association for the early attentional processing of cues in the visual periphery, but additionally was influenced by the uncertainty of the shock prediction after participants fixated on the cues. These findings are in accord with attentional learning theories that formalize how associative learning shapes automatic attention.
Formal theories have linked pathological anxiety to a failure in fear response inhibition. Previously, we showed that aberrant response inhibition is not restricted to anxiety patients, but can also be observed in anxiety-prone adults. However, less is known about the influence of currently experienced levels of anxiety on inhibitory learning. The topic is highly important as state anxiety has a debilitating effect on cognition, emotion, and physiology and is linked to several anxiety disorders. In the present study, healthy female volunteers performed a fear conditioning task, after being informed that they will have to perform the Trier Social Stress Test task (n = 25; experimental group) or a control task (n = 25; control group) upon completion of the conditioning task. The results showed that higher levels of state anxiety corresponded with a reduced discrimination between a stimulus (CS+) typically followed by an aversive event and a stimulus (CS-) that is never followed by an aversive event both during the acquisition and the extinction phase. No effect of state anxiety on the skin conductance response associated with CS+ and CS- was found. Additionally, higher levels of state anxiety coincided with more negative valence ratings of the CSs. The results suggest that increased stress-induced state anxiety might lead to stimulus generalization during fear acquisition, thereby impairing associative learning.
Research on avoidance conditioning began in the late 1930s as a way to use laboratory experiments to better understand uncontrollable fear and anxiety. Avoidance was initially conceived of as a two-factor learning process in which fear is first acquired through Pavlovian aversive conditioning (so-called fear conditioning), and then behaviors that reduce the fear aroused by the Pavlovian conditioned stimulus are reinforced through instrumental conditioning. Over the years, criticisms of both the avoidance paradigm and the two-factor fear theory arose. By the mid-1980s, avoidance had fallen out of favor as an experimental model relevant to fear and anxiety. However, recent progress in understanding the neural basis of Pavlovian conditioning has stimulated a new wave of research on avoidance. This new work has fostered new insights into contributions of not only Pavlovian and instrumental learning but also habit learning, to avoidance, and has suggested that the reinforcing event underlying the instrumental phase should be conceived in terms of cellular and molecular events in specific circuits rather than in terms of vague notions of fear reduction. In our approach, defensive reactions (freezing), actions (avoidance) and habits (habitual avoidance) are viewed as being controlled by unique circuits that operate nonconsciously in the control of behavior, and that are distinct from the circuits that give rise to conscious feelings of fear and anxiety. These refinements, we suggest, overcome older criticisms, justifying the value of the new wave of research on avoidance, and offering a fresh perspective on the clinical implications of this work.Molecular Psychiatry advance online publication, 18 October 2016; doi:10.1038/mp.2016.166.
Elevated levels of fear and avoidance are core symptoms across the anxiety disorders. It has long been known that fear serves to motivate avoidance. Consequently, fear extinction has been the primary focus in pre-clinical anxiety research for decades, under the implicit assumption that removing the motivator of avoidance (fear) would automatically mitigate the avoidance behaviors as well. Although this assumption has intuitive appeal, it has received little scientific scrutiny. The scarce evidence from animal studies is mixed, while the assumption remains untested in humans. The current study applied an avoidance conditioning protocol in humans to investigate the effects of fear extinction on the persistence of low-cost avoidance. Online danger-safety ratings and skin conductance responses documented the dynamics of conditioned fear across avoidance and extinction phases. Anxiety- and avoidance-related questionnaires explored individual differences in rates of avoidance. Participants first learned to click a button during a predictive danger signal, in order to cancel an upcoming aversive electrical shock (avoidance conditioning). Next, fear extinction was induced by presenting the signal in the absence of shocks while button-clicks were prevented (by removing the button in Experiment 1, or by instructing not to click the button in Experiment 2). Most importantly, post-extinction availability of the button caused a significant return of avoidant button-clicks. In addition, trait-anxiety levels correlated positively with rates of avoidance during a predictive safety signal, and with the rate of pre- to post-extinction decrease during this signal. Fear measures gradually decreased during avoidance conditioning, as participants learned that button-clicks effectively canceled the shock. Preventing button-clicks elicited a sharp increase in fear, which subsequently extinguished. Fear remained low during avoidance testing, but danger-safety ratings increased again when button-clicks were subsequently prevented. Together, these results show that low-cost avoidance behaviors can persist following fear extinction and induce increased threat appraisal. On the other hand, fear extinction did reduce augmented rates of unnecessary avoidance during safety in trait-anxious individuals, and instruction-based response prevention was more effective than removal of response cues. More research is needed to characterize the conditions under which fear extinction might mitigate avoidance.
Change your lifestyle: decrease your energy intake and increase your energy expenditure, is what obesity experts tell people who need to lose weight. Though the advice might be correct, it appears to be extremely difficult to change one’s lifestyle. Unhealthy habits usually are ingrained and hard to change, especially for people with an “obese cognitive profile.” Knowledge of the cognitive mechanisms that maintain unhealthy eating habits is necessary for the development of interventions that can change behavior effectively. This paper discusses some cognitive processes that might maintain unhealthy eating habits and make healthier eating difficult, like increased food cue reactivity, weak executive skills and attention bias. An effort is also done to translate these basic scientific findings into new interventions which aim to tackle the sabotaging cognitive processes. Preliminary studies into the effectiveness of these interventions, if available, are presented.
Avoidance is a key characteristic of adaptive and maladaptive fear. Here, we review past and
contemporary theories of avoidance learning. Based on the theories, experimental findings and
clinical observations reviewed, we distil key principles of how adaptive and maladaptive
avoidance behavior is acquired and maintained. We highlight clinical implications of avoidance
learning theories and describe intervention strategies that could reduce maladaptive avoidance and
prevent its return. We end with a brief overview of recent developments and avenues for further research.
The ego-syntonic nature of anorexia nervosa (AN) emphasizes how some aspects of this disorder can be highly valuable to patients. To understand the different perspectives that patients with AN hold about their condition, we explored the meanings they attribute to it. Thirty-four AN patients were asked to write a letter to their condition describing what it represents and means to them. Letters were then evaluated using a standardized coding scheme. Three pro-codes resulted to be mostly represented: difference (i.e. feeling different from others because of AN), company (i.e. being protected by the disorder), and identity (i.e. being totally represented by the illness). Some anti-codes were also particularly used: anger/hate, expressing anger toward AN, fear/distress, betrayal/pretend (i.e. feeling cheated by the disorder), and loss/waste (i.e. describing a feeling of life being wasted). In addition to pro- and anti-codes, the ambivalence theme was also well represented. Given the complex adaptive function of this disorder, this study may provide a framework of different perspectives that therapists could refer to and patients could identify with during the therapeutic process toward discovering individual meanings of the disorder.
Earlier studies provided preliminary support for the role of classical conditioning as a pathway of disgust learning, yet this evidence has been limited to self-report. This study included facial electromyographical (EMG) measurements (corrugator and levator muscles) and a behavioural approach task to assess participants' motivation-to-eat the actual food items (conditioned stimuli, CS). Food items served as CS and film excerpts of a woman vomiting served as unconditioned stimuli (US). Following acquisition the CS+ (neutral CS paired with US disgust) was rated as more disgusting and less positive. Notably, the conditioned response was transferred to the actual food items as evidenced by participants' reported lowered willingness-to-eat. Participants also showed heightened EMG activity in response to the CS+ which seemed driven by the corrugator indexing a global negative affect. These findings suggest that classical conditioning as a pathway of disgust learning can be reliably observed in subjective but not in disgust-specific physiological responding.
Clinical fear is at the core of anxiety disorders. Considerable research has examined processes through which clinical fears are learned and unlearned (i.e., acquisition, generalization, extinction, return of fear) in anxiety disorders. Empirically supported models of these processes implicate both associative and instrumental learning. Research has also delineated that avoidance (i.e., behaviors intended to prevent aversive experiences) and fear approach (i.e., behaviors that involve exposure to one's fear) modulate fear learning, yet these processes remain under-researched in anxiety-based disorders. The purpose of the current review is to a) review existing research on clinical fear learning, incorporating fear approach, avoidance, and inhibitory learning, and b) extend this model to advance the understanding of fear-based learning in eating disorders. Implications for research and treatment are discussed, including how the anxiety field can inform eating disorder research and the importance of empirically testing fear learning in eating disorders to improve treatment.
Food choice and its underlying processes is understudied in Bulimia Nervosa (BN) and Anorexia Nervosa (AN). Thus, we examined cognitive processes during food choice through mouse tracing in AN (n = 36) and BN (n = 27) undergoing inpatient treatment. Both patient groups and matched healthy controls (HC, n = 59) made 153 binary food choices before rating all foods on their liking and calorie density. Choice outcomes and corresponding mouse movements were modelled as a function of inpatient treatment stage in our analyses.
Compared to patients with BN and HC, those with AN showed a clear calorie avoidance on most trials. Yet, mouse paths in AN patients early in treatment, revealed a late direction reversal (‘change of mind’, CoM) on high-calorie choices. AN patients later in treatment, by contrast, showed fewer CoM alongside more choices for – and liking of – high-calorie foods. Patients with BN showed more CoM trials during low-calorie choices and low-calorie choices were more frequent in patients later in treatment. Thus, relative to patients early in treatment, patients who are later in treatment show less of the overall group pattern of consistently choosing low-calorie food (AN) or high-calorie food (BN). Less cognitive regulation (fewer CoM trials) went along with higher liking for high-calorie foods in AN. These cross-sectional differences between AN early and late in treatment might reflect the formation of healthier habits. In addition, clear patient group differences suggest more specific treatment strategies.
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.
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.
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.
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.
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.
Objective
This meta‐analysis examines the efficacy of recently developed psychological treatments for anorexia nervosa, compared with control condition. Outcome criteria are weight gain, eating disorder pathology, and quality of life.
Method
Twelve thousand nine hundred ninety‐seven abstracts, published between 1980 and 2017, were retrieved. End‐of‐treatment data from 1,279 participants, from 15 of 17 eligible studies, were used to calculate pooled‐effect sizes (Hedges' g) for outcome using random‐effects model. Subgroup analyses were used to explore the influence of various patient and study characteristics.
Results
No significant differences between psychological treatment and controls were found on weight gain, g = 0.07, 95% CI [−0.09, 0.23], eating disorder pathology, g = 0.06, 95% CI [−0.10, 0.21], and quality of life, g = −0.11, 95% CI [−0.36, 0.15]. Studies including only patients over 18 years of age were more effective on weight gain than studies including adolescents as well. High‐quality studies and studies with reported therapist training had larger effects on weight gain and quality of life compared with low‐quality studies and studies without reported training.
Conclusions
Despite progress in the development of specialized treatments, the efficacy of psychological treatment over an active control condition could not be established. Outcomes, however, are obscured by low‐quality and heterogeneous studies.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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).
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.