Compulsivity in anorexia nervosa: a transdiagnostic concept

[Anorexia nervosa: An addiction? Application of the addiction model to eating disorders. A narrative commented review]

OBJECTIVES

Addiction offers a framework for the understanding of eating disorders, particularly those characterized by hyperphagia, with growing interest in food addiction. However, the application of the addiction model to anorexia nervosa remains more controversial. In this commented narrative review, we examine and discuss the addictive features of anorexia nervosa.

METHODS

Commented narrative review of the literature.

RESULTS

Anorexia nervosa could be the consequence of the loss of control of several objects of positive reinforcement: food restriction, physical hyperactivity, and food itself. Craving has been little studied in the field of eating disorders. When investigated, studies mainly focus on food cravings and tend to highlight food cravings that are inversely correlated with the restrictive nature of the disorder. This would thus be less found in anorexia nervosa, in which it is nevertheless reported. The existence of a pre-existing food craving, or its appearance secondary to food restriction, is currently under discussion. In the meantime, the question of a craving for food restriction, underpinned by the gratifying effect of fasting, is raised.

CONCLUSIONS

The management of eating disorders has its place within the addiction care sectors. An integrative approach should be favored, for anorexia nervosa, combining, on the one hand, classic nutritional care, and, on the other hand, care within the framework of addiction treatment. Finally, in people with an eating disorder, the search for an addiction to food, food restriction and physical activity, including a systematic assessment of craving, should be systematized.

Corpus callosum morphology and relationships to illness phenotypes in individuals with anorexia nervosa

Anorexia nervosa is an often-severe psychiatric illness characterized by significantly low body weight, fear of gaining weight, and distorted body image. Multiple neuroimaging studies have shown abnormalities in cortical morphology, mostly associated with the starvation state. Investigations of white matter, while more limited in number, have suggested global and regional volume reductions, as well as abnormal diffusivity in multiple regions including the corpus callosum. Yet, no study has specifically examined thickness of the corpus callosum, a large white matter tract instrumental in the inter-hemispheric integration of sensory, motor, and cognitive information. We analyzed MRI data from 48 adolescents and adults with anorexia nervosa and 50 healthy controls, all girls/women, to compare corpus callosum thickness and examined relationships with body mass index (BMI), illness duration, and eating disorder symptoms (controlling for BMI). There were no significant group differences in corpus callosum thickness. In the anorexia nervosa group, severity of body shape concerns was significantly, positively correlated with callosal thickness in the rostrum, genu, rostral body, isthmus, and splenium. In addition, there were significant positive correlations between eating disorder-related obsessions and compulsions and thickness of the anterior midbody, rostral body, and splenium. There were no significant associations between callosal thickness and BMI or illness duration. In sum, those with AN with worse concerns about bodily appearance and worse eating disorder-related obsessive thought patterns and compulsive behaviours have regionally thicker corpus callosum, independent of current weight status. These findings provide important neurobiological links to key, specific eating disorder behavioural phenotypes.

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

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

Restrained eating and alcohol use: Testing drinking to cope and impulsivity as moderators

The association between restrained eating and alcohol use remains poorly understood among undergraduates. Consistent with tension reduction theory, individuals with disordered eating may be motivated to drink alcohol to cope with negative emotionality. Perhaps what pushes them to drink despite restriction goals is impulsivity. The combined impact of drinking to cope and impulsivity on the theoretically complex link between restrained eating and alcohol outcomes has not been previously examined. The current study tested the moderating effect of drinking to cope and impulsivity on the association between restrained eating and alcohol use and problems. Undergraduates (N = 1,619) self-reported on eating disorder symptoms, alcohol use motives, impulsivity, and alcohol outcomes. A moderation model revealed that restrained eating predicted past 30-day alcohol use, but only for women high in both drinking to cope and impulsivity. These findings help characterize alcohol misuse risk among young adults who restrict their eating, thereby, results may inform interventions.

The Efficacy of Cognitive Remediation Therapy for Anorexia Nervosa: A Systematic Review of Systematic Reviews

BACKGROUND

Cognitive remediation therapy (CRT) for anorexia nervosa (AN) is an intervention specifically focused on addressing cognitive difficulties associated with the eating disorder. This systematic review of systematic reviews and meta-analysis aimed to provide a summary of the existing literature examining the efficacy of CRT in improving the neuropsychological, psychological, and clinical parameters of patients with AN.

METHODS

Systematic reviews and meta-analyses were sought in electronic databases, encompassing studies that explored the impact of CRT on AN. Three eligible reviews were identified based on the inclusion criteria. The Revised Assessment of Multiple SysTemAtic Reviews (R-AMSTAR) was employed to evaluate the methodological quality of the reviews, and all included reviews demonstrated satisfactory methodological quality with an R-AMSTAR score of ≥22. Relevant information was extracted from each review and qualitatively compiled.

RESULTS

Findings suggest that CRT can help people increase their awareness of cognitive styles and information processing and have a positive effect on patients' responses to treatment.

CONCLUSIONS

Further research is required to better understand its impact on other relevant outcomes, including psychological variables, to optimize the treatment's benefits.

Adaptive learning from outcome contingencies in eating-disorder risk groups

Eating disorders are characterised by altered eating patterns alongside overvaluation of body weight or shape, and have relatively low rates of successful treatment and recovery. Notably, cognitive inflexibility has been implicated in both the development and maintenance of eating disorders, and understanding the reasons for this inflexibility might indicate avenues for treatment development. We therefore investigate one potential cause of this inflexibility: an inability to adjust learning when outcome contingencies change. We recruited (n = 82) three groups of participants: those who had recovered from anorexia nervosa (RA), those who had high levels of eating disorder symptoms but no formal diagnosis (EA), and control participants (HC). They performed a reinforcement learning task (alongside eye-tracking) in which the volatility of wins and losses was independently manipulated. We predicted that both the RA and EA groups would adjust their learning rates less than the control participants. Unexpectedly, the RA group showed elevated adjustment of learning rates for both win and loss outcomes compared to control participants. The RA group also showed increased pupil dilation to stable wins and reduced pupil dilation to stable losses. Their learning rate adjustment was associated with the difference between their pupil dilation to volatile vs. stable wins. In conclusion, we find evidence that learning rate adjustment is unexpectedly higher in those who have recovered from anorexia nervosa, indicating that the relationship between eating disorders and cognitive inflexibility may be complex. Given our findings, investigation of noradrenergic agents may be valuable in the field of eating disorders.

Conceptualising compulsivity through network analysis: A two-sample study

Compulsivity is a transdiagnostic construct crucial to understanding multiple psychiatric conditions and problematic repetitive behaviours. Despite being identified as a clinical- and research-relevant construct, there are limited insights into the internal conceptual structure of compulsivity. To provide a more nuanced understanding of compulsivity, the current study estimated the structure of compulsivity (indexed using the previously validated Cambridge-Chicago Compulsivity Trait Scale, CHI-T) among two large-scale and geographically distinct samples using the network estimation method. The samples consisted of a United Kingdom cohort (n = 122,346, 51.4% female, Mean age = 43.7, SD = 16.5, range = 9-86 years) and a South Africa cohort (n = 2674, 65.6% female, Mean age = 24.6, SD = 8.6, range = 18-65 years). Network community analysis demonstrated that compulsivity was constituted of three interrelated dimensions, namely: perfectionism, cognitive rigidity and reward drive. Further, 'Completion leads to soothing' and 'Difficulty moving from task to task' were identified as core (central nodes) to compulsivity. The dimensional structure and central nodes of compulsivity networks were consistent across the two samples. These findings facilitate the conceptualisation and measurement of compulsivity and may contribute to the early detection and treatment of compulsivity-related disorders.

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

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

Eating disorder symptoms and control-seeking behavior

OBJECTIVE

Eating disorders (EDs) are a heterogenous group of disorders characterized by disturbed eating patterns. Links have been made between ED symptoms and control-seeking behaviors, which may cause relief from distress. However, whether direct behavioral measures of control-seeking behavior correlate with ED symptoms has not been directly tested. Additionally, existing paradigms may conflate control-seeking behavior with uncertainty-reducing behavior.

METHOD

A general population sample of 183 participants completed part in an online behavioral task, in which participants rolled a die in order to obtain/avoid a set of numbers. Prior to each roll, participants could choose to change arbitrary features of the task (such as the color of their die) or view additional information (such as the current trial number). Selecting these Control Options could cost participants points or not (Cost/No-Cost conditions). Each participant completed all four conditions, each with 15 trials, followed by a series of questionnaires, including the Eating Attitudes Test-26 (EAT-26), the Intolerance of Uncertainty Scale, and the Obsessive-Compulsive Inventory-Revised (OCI-R).

RESULTS

A Spearman's rank test indicated no significant correlation between total EAT-26 score and total number of Control Options selected, with only elevated scores on a measure of obsessions and compulsivity (OCI-R) correlating with the total number of Control Options selected (rs  = .155, p = .036).

DISCUSSION

In our novel paradigm, we find no relationship between EAT-26 score and control-seeking. However, we do find some evidence that this behavior may be present in other disorders that often coincide with ED diagnosis, which may indicate that transdiagnostic factors such as compulsivity are important to control-seeking.

The absence of association between anorexia nervosa and smoking: converging evidence across two studies

Previous studies have found increased smoking prevalence amongst adults with anorexia nervosa (AN) compared to the general population. The current investigation explored bidirectional associations between AN and smoking behaviour (initiation and heaviness), to address questions surrounding causation. In Study One, logistic regression models with variance robust standard errors assessed longitudinal associations between AN and smoking, using data from adolescent participants of the Avon Longitudinal Study of Parents and Children (N = 5100). In Study Two, two-sample Mendelian randomisation (MR) tested possible causal effects using summary statistics from publicly available genome-wide association studies (GWAS). Study One provided no clear evidence for a predictive effect of AN on subsequent smoking behaviour, or for smoking heaviness/initiation predicting later AN. MR findings did not support causal effects between AN and smoking behaviour, in either direction. Findings do not support predictive or causal effects between AN and smoking behaviour. Previously reported associations may have been vulnerable to confounding, highlighting the possibility of smoking and AN sharing causal risk factors.

Hooked on weight control: An economic theory of anorexia nervosa and its impact on health and longevity

In this paper, I integrate a theory of body image, weight control, and addiction in a life cycle model with health deficit accumulation in order to explain the phenomenon of anorexia nervosa and its impact on health and longevity. Individuals consume normal goods and foods and can work off excess calories with physical exercise. There exists a healthy body mass index and deviations from it increasingly cause health deficits due to obesity or underweight. There exists also a subjective target weight and being heavier than target weight causes a loss of utility from body image. Anorexia is initiated in individuals who are particularly successful in weight control and prone to addiction. Addiction to weight control motivates anorexic individuals to perpetually adjust their target weight downwards and to eat less and exercise more. With declining weight, health deficits accumulate faster and mortality risk rises. I calibrate the model to an average American woman with bmi 28. Due to weight loss addiction, the bmi declines to a level of 15 and causes an expected loss of 15 years of life. I also discuss potential therapies and recovery from the disease.

Food Restriction in Anorexia Nervosa in the Light of Modern Learning Theory: A Narrative Review

Improvements in the clinical management of anorexia nervosa (AN) are urgently needed. To do so, the search for innovative approaches continues at laboratory and clinical levels to translate new findings into more effective treatments. In this sense, modern learning theory provides a unifying framework that connects concepts, methodologies and data from preclinical and clinical research to inspire novel interventions in the field of psychopathology in general, and of disordered eating in particular. Indeed, learning is thought to be a crucial factor in the development/regulation of normal and pathological eating behaviour. Thus, the present review not only tries to provide a comprehensive overview of modern learning research in the field of AN, but also follows a transdiagnostic perspective to offer testable explanations for the origin and maintenance of pathological food rejection. This narrative review was informed by a systematic search of research papers in the electronic databases PsycInfo, Scopus and Web of Science following PRISMA methodology. By considering the number and type of associations (Pavlovian, goal-directed or habitual) and the affective nature of conditioning processes (appetitive versus aversive), this approach can explain many features of AN, including why some patients restrict food intake to the point of life-threatening starvation and others restrict calorie intake to lose weight and binge on a regular basis. Nonetheless, it is striking how little impact modern learning theory has had on the current AN research agenda and practice.

The Treatment Experience of Anorexia Nervosa in Adolescents from Healthcare Professionals' Perspective: A Qualitative Study

Anorexia nervosa (AN) is a serious psychiatric illness with a high mortality rate and a poor outcome. AN in adolescents can be difficult to treat. The prognosis of patients with AN depends highly on how early specialized AN treatment starts. Therefore, the purpose of this study was to explore the experiences of healthcare professionals in treating adolescents with AN. A qualitative study approach was conducted. Through semi-structured interviews, 16 healthcare professionals, including 10 nurses, 3 dieticians and 3 physicians from the paediatric ward at a university-affiliated medical centre in central Taiwan, shared their experiences. Recorded interviews were transcribed and analyzed by content analysis. Five themes and ten subthemes were identified: 1. Building a trusting relationship first: (a) spending time to build trust with the client and (b) establishing a relationship with the client's parents; 2. The key to treatment success: (a) Clients' awareness of the illness and (b) parents' support for clients; 3. Consistency of team treatment goals: (a) maintaining stable vital signs and (b) achieving caloric intake; 4. Empowerment with knowledge about anorexia: (a) continuing education for healthcare professionals and (b) interdisciplinary collaborative care; and 5. Using different interaction strategies: (a) the hard approach and (b) the soft approach. In conclusion, the findings will provide important information for healthcare professionals to apply in monitoring the psychological and emotional states of adolescents with AN. The findings indicate that healthcare professionals should invite parents to participate in the treatment, support and guide them in their adolescent care, develop scales of family stress and support for AN in adolescents, develop interventions, and establish an early therapeutic alliance.

Pavlovian-to-Instrumental Transfer across Mental Disorders: A Review

A mechanism known as Pavlovian-to-instrumental transfer (PIT) describes a phenomenon by which the values of environmental cues acquired through Pavlovian conditioning can motivate instrumental behavior. PIT may be one basic mechanism of action control that can characterize mental disorders on a dimensional level beyond current classification systems. Therefore, we review human PIT studies investigating subclinical and clinical mental syndromes. The literature prevails an inhomogeneous picture concerning PIT. While enhanced PIT effects seem to be present in non-substance-related disorders, overweight people, and most studies with AUD patients, no altered PIT effects were reported in tobacco use disorder and obesity. Regarding AUD and relapsing alcohol-dependent patients, there is mixed evidence of enhanced or no PIT effects. Additionally, there is evidence for aberrant corticostriatal activation and genetic risk, e.g., in association with high-risk alcohol consumption and relapse after alcohol detoxification. In patients with anorexia nervosa, stronger PIT effects elicited by low caloric stimuli were associated with increased disease severity. In patients with depression, enhanced aversive PIT effects and a loss of action-specificity associated with poorer treatment outcomes were reported. Schizophrenic patients showed disrupted specific but intact general PIT effects. Patients with chronic back pain showed reduced PIT effects. We provide possible reasons to understand heterogeneity in PIT effects within and across mental disorders. Further, we strengthen the importance of reliable experimental tasks and provide test-retest data of a PIT task showing moderate to good reliability. Finally, we point toward stress as a possible underlying factor that may explain stronger PIT effects in mental disorders, as there is some evidence that stress per se interacts with the impact of environmental cues on behavior by selectively increasing cue-triggered wanting. To conclude, we discuss the results of the literature review in the light of Research Domain Criteria, suggesting future studies that comprehensively assess PIT across psychopathological dimensions.

Cardiopulmonary exercise testing for patients with anorexia nervosa: a case-control study

PURPOSE

Patients with anorexia nervosa (AN) require appropriate nutrient therapy and physical activity management. Eating disorder treatment guidelines do not include safe, evidence-based intensity criteria for exercise. This study used cardiopulmonary exercise testing (CPX) to evaluate the exercise tolerance of patients with AN.

METHODS

CPX was performed with 14 female patients with AN admitted to a specialized eating disorder unit between 2015 and 2019. Their anaerobic threshold (AT) was determined by assessing their exercise tolerance using CPX and compared with 14 healthy controls (HC). The metabolic equivalents (AT-METS) were compared when AT was reached. We examined factors related to AT (AN-AT) in the AN group, including age, body mass index (BMI), previous lowest weight, minimum BMI, past duration of BMI < 15, exercise history, and ΔHR (heart rate at the AT-resting heart rate).

RESULTS

The AT of the AN group (BMI: 15.7 [Mean] ± 1.8 standard deviation [SD]) was significantly lower than that of the HC group (BMI: 19.7 ± 1.8) (AN: 10.0 ± 1.8 vs. HC: 15.2 ± 3.0 ml/kg/min, P < 0.001). AT-METS was also significantly lower in the AN group than in the HC group (AN: 2.9 ± 0.52 vs. HC: 4.4 ± 0.91, P < 0.001). AN-AT was highly influenced by ΔHR.

CONCLUSIONS

This study showed that AT and AT-METS were lower in patients with AN than in HC. Patients with AN should be prescribed light-intensity aerobic exercise, and the current findings may help develop future physical management guidelines for patients with AN.

LEVEL OF EVIDENCE

III: Evidence obtained from case-control analytic studies.

The effect of body image dissatisfaction on goal-directed decision making in a population marked by negative appearance beliefs and disordered eating

Eating disorders are associated with one of the highest mortality rates among all mental disorders, yet there is very little research about them within the newly emerging and promising field of computational psychiatry. As such, we focus on investigating a previously unexplored, yet core aspect of eating disorders-body image dissatisfaction. We continue a freshly opened debate about model-based learning and its trade-off against model-free learning-a proxy for goal-directed and habitual behaviour. We perform a behavioural study that utilises a two-step decision-making task and a reinforcement learning model to understand the effect of body image dissatisfaction on model-based learning in a population characterised by high scores of disordered eating and negative appearance beliefs, as recruited using Prolific. We find a significantly reduced model-based contribution in the body image dissatisfaction task condition in the population of interest as compared to a healthy control. This finding suggests general deficits in deliberate control in this population, leading to habitual, compulsive-like behaviours (body checking) dominating the experience. Importantly, the results may inform treatment approaches, which could focus on enhancing the reliance on goal-directed decision making to help cope with unwanted behaviours.

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

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

Understanding relations between intolerance of uncertainty and body checking and body avoiding in anorexia nervosa

BACKGROUND

A key feature of anorexia nervosa is body image disturbances and is often expressed by dysfunctional body-related behaviours such as body checking and body avoiding. These behaviours are thought to contribute to both the maintenance and relapse of AN, yet empirical evidence is scarce. One variable that may contribute to the need for engaging in these behaviours is intolerance of uncertainty. This study aims to investigate body checking and body avoiding and its relations with intolerance of uncertainty in women with anorexia nervosa (AN-ill; 70), women recovered from AN (AN-rec; 85) and control group (127).

METHODS

Three questionnaires were completed, measuring eating pathology, intolerance of uncertainty and body checking and body avoiding. One-way ANOVAS were used to test group differences. Moderation analyses were used to investigate associations between variables.

RESULTS

Levels of intolerance of uncertainty, body checking and body avoiding were highest in AN-ill followed by AN-rec and, lastly, the control group, confirming group differences. Intolerance of uncertainty was associated with body checking in the AN-rec group and the control group but not in the AN-ill group. The association between intolerance of uncertainty and body avoiding was reported in the AN-rec group and only marginally in the control group.

CONCLUSION

Levels of intolerance of uncertainty, body checking and body avoiding were highest in AN-ill, however still elevated in AN-rec, confirming the presence of body image disturbances, even after recovery. The unique associations between intolerance of uncertainty and body checking and body avoiding within the studied groups may represent different stages of the illness. In the AN-rec group, the relation between intolerance of uncertainty, body checking and body avoiding may be driven by trait anxiety. For AN-ill group, body checking and body avoiding may eventually have grown into habitual patterns, rather than a strategy to ameliorate anxiety and uncertainty. Women with anorexia nervosa often experience disturbances in their body image and are expressed in body-related behaviours such as body checking and body avoiding. These behaviours are thought to contribute to both the maintenance and relapse of anorexia nervosa. Intolerance of uncertainty is defined as the incapacity to tolerate uncertainty and may contribute to the need for engaging in these behaviours. This study aims to investigate body checking and body avoiding and its relations with intolerance of uncertainty in women with anorexia nervosa (AN-ill; 70), women recovered from AN (AN-rec; 85) and control group (127). Three questionnaires were completed, measuring eating pathology, intolerance of uncertainty and body checking and body avoiding. Levels of intolerance of uncertainty, body checking and body avoiding were highest in AN-ill and still elevated in AN-rec, even after recovery. The associations between intolerance of uncertainty and body checking and body avoiding within the studied groups may represent different stages of the illness. In the AN-rec group, the relation between intolerance of uncertainty, body checking and body avoiding may be driven by trait anxiety. For AN-ill group, body checking and body avoiding may have grown into habitual patterns, rather than a strategy to ameliorate anxiety and uncertainty.

Vasopressin neurons in the paraventricular hypothalamus promote wakefulness via lateral hypothalamic orexin neurons

The sleep-wakefulness cycle is regulated by complicated neural networks that include many different populations of neurons throughout the brain. Arginine vasopressin neurons in the paraventricular nucleus of the hypothalamus (PVH^AVP) regulate various physiological events and behaviors, such as body-fluid homeostasis, blood pressure, stress response, social interaction, and feeding. Changes in arousal level often accompany these PVH^AVP-mediated adaptive responses. However, the contribution of PVH^AVP neurons to sleep-wakefulness regulation has remained unknown. Here, we report the involvement of PVH^AVP neurons in arousal promotion. Optogenetic stimulation of PVH^AVP neurons rapidly induced transitions to wakefulness from both NREM and REM sleep. This arousal effect was dependent on AVP expression in these neurons. Similarly, chemogenetic activation of PVH^AVP neurons increased wakefulness and reduced NREM and REM sleep, whereas chemogenetic inhibition of these neurons significantly reduced wakefulness and increased NREM sleep. We observed dense projections of PVH^AVP neurons in the lateral hypothalamus with potential connections to orexin/hypocretin (LH^Orx) neurons. Optogenetic stimulation of PVH^AVP neuronal fibers in the LH immediately induced wakefulness, whereas blocking orexin receptors attenuated the arousal effect of PVH^AVP neuronal activation drastically. Monosynaptic rabies-virus tracing revealed that PVH^AVP neurons receive inputs from multiple brain regions involved in sleep-wakefulness regulation, as well as those involved in stress response and energy metabolism. Moreover, PVH^AVP neurons mediated the arousal induced by novelty stress and a melanocortin receptor agonist melanotan-II. Thus, our data suggested that PVH^AVP neurons promote wakefulness via LH^Orx neurons in the basal sleep-wakefulness and some stressful conditions.

Interpersonal, affective and compulsive features of driven exercise in anorexia nervosa

BACKGROUND

This preregistered (https://osf.io/g9ajb) analysis sought to integrate the current literature on trait compulsivity into maintenance models of driven exercise in anorexia nervosa (AN). We tested whether compulsivity increases the likelihood of driven exercise via interpersonal and affect-regulatory pathways.

METHODS

We used multilevel structural equation modeling to test the hypothesis that trait compulsivity predicts a stronger within-person link between affect-regulatory difficulties or interpersonal sensitivity and driven exercise in female adolescents and adults with AN. We used data from five assessments across inpatient treatment and 6-months follow-up of 207 adult and adolescent patients with AN (1035 datapoints).

RESULTS

In line with our hypotheses, patients who generally experienced more affect-regulatory difficulties or stronger interpersonal sensitivity tended to engage in driven exercise more strongly. Moreover, high levels of trait compulsivity amplified the effect of interpersonal sensitivity on driven exercise across time. Contrary to our hypotheses, the link between affect regulation and driven exercise was not moderated by compulsivity. Similar effects on general eating disorder psychopathology were found, but no cross-level moderation effect of compulsivity.

LIMITATIONS

Due to sample size, potential AN subtype-dependent effects were not analyzed.

CONCLUSION

Our results suggest that driven exercise coincides with self-reported experiences of interpersonal sensitivity and that this link varies as a function of compulsivity such that the within-person coupling is stronger among those scoring high on compulsivity. To derive clinically useful functional models of driven exercise, future studies might use intensive longitudinal data to investigate its momentary associations with affect and interpersonal sensitivity in the context of compulsive traits.

The hypothalamus for whole-body physiology: from metabolism to aging

Obesity and aging are two important epidemic factors for metabolic syndrome and many other health issues, which contribute to devastating diseases such as cardiovascular diseases, stroke and cancers. The brain plays a central role in controlling metabolic physiology in that it integrates information from other metabolic organs, sends regulatory projections and orchestrates the whole-body function. Emerging studies suggest that brain dysfunction in sensing various internal cues or processing external cues may have profound effects on metabolic and other physiological functions. This review highlights brain dysfunction linked to genetic mutations, sex, brain inflammation, microbiota, stress as causes for whole-body pathophysiology, arguing brain dysfunction as a root cause for the epidemic of aging and obesity-related disorders. We also speculate key issues that need to be addressed on how to reveal relevant brain dysfunction that underlines the development of these disorders and diseases in order to develop new treatment strategies against these health problems.

Paraventricular hypothalamic vasopressin neurons induce self-grooming in mice

Self-grooming plays an essential role in hygiene maintenance, thermoregulation, and stress response. However, the neural populations involved in self-grooming remain largely unknown. The paraventricular hypothalamic nucleus (PVH) has been implicated in the regulation of self-grooming. Arginine vasopressin-producing neurons are among the major neuronal populations in the PVH (PVH^AVP), which play important roles in water homeostasis, blood pressure regulation, feeding, and stress response. Here, we report the critical role of PVH^AVP neurons in the induction of self-grooming. Optogenetic activation of PVH^AVP neurons immediately induced self-grooming in freely moving mice. Chemogenetic activation of these neurons also increased time spent self-grooming. In contrast, their chemogenetic inhibition significantly reduced naturally occurring self-grooming, suggesting that PVH^AVP-induced grooming has physiological relevance. Notably, optogenetic activation of PVH^AVP neurons triggered self-grooming over other adaptive behaviors, such as voracious feeding induced by fasting and social interaction with female mice. Thus, our study proposes the novel role of PVH^AVP neurons in regulating self-grooming behavior and, consequently, hygiene maintenance and stress response. Furthermore, uncontrolled activation of these neurons may be potentially relevant to diseases characterized by compulsive behaviors and impaired social interaction, such as autism, obsessive–compulsive disorder, and anorexia nervosa.

Deep Brain Stimulation of the Nucleus Accumbens in Severe Enduring Anorexia Nervosa: A Pilot Study

Introduction

Anorexia nervosa (AN) is one of the most debilitating psychiatric disorders, becoming severe and enduring in a third of cases; with few effective treatments. Deep brain stimulation is a reversible, adjustable neurosurgical procedure that has been gaining ground in psychiatry as a treatment for depression and obsessive-compulsive disorder, yet few studies have investigated AN. Abnormal eating behavior and the compulsive pursuit of thinness in AN is, in part, a consequence of dysfunction in reward circuitry and the nucleus accumbens (NAcc) is central to reward processing.

Methods

Phase 1 prospective open-label pilot study of seven individuals with severe enduring AN. Electrodes were implanted bilaterally into the NAcc with stimulation at the anterior limb of the internal capsule using rechargeable implantable pulse generators. The protocol of 15 months included 12 months of deep brain stimulation incorporating two consecutive, randomized blind on-off fortnights 9 months after stimulation onset. The primary objectives were to investigate safety and feasibility, together with changes in eating disorder psychopathology.

Results

Feasibility and safety was demonstrated with no serious adverse events due to deep brain stimulation. Three patients responded to treatment [defined as > 35% reduction in Eating Disorders Examination (EDE) score at 12 months] and four patients were non-responders. Responders had a statistically significant mean reduction in EDE scores (50.3% reduction; 95% CI 2.6-98.2%), Clinical Impairment Assessment (45.6% reduction; 95% CI 7.4-83.7%). Responders also had a statistically significant mean reduction in Hamilton Depression Scale, Hamilton Anxiety Scale and Snaith-Hamilton pleasure scale. There were no statistically significant changes in Body Mass Index, Yale-Brown-Cornell Eating Disorder Scale, Yale-Brown Obsessive-Compulsive Scale and World Health Organization Quality of Life Psychological subscale.

Conclusion

This study provides some preliminary indication that deep brain stimulation to the NAcc. Might potentially improve some key features of enduring AN. In this small study, the three responders had comorbid obsessive-compulsive disorder which predated AN diagnosis. Future studies should aim to further elucidate predictors of outcome.

Clinical Trial Registration

[www.ClinicalTrials.gov], identifier [Project ID 128658].

Guts Imbalance Imbalances the Brain: A Review of Gut Microbiota Association With Neurological and Psychiatric Disorders

Over the last 10 years, there has been a growing interest in the relationship between gut microbiota, the brain, and neurologic-associated affections. As multiple preclinical and clinical research studies highlight gut microbiota’s potential to modulate the general state of health state, it goes without saying that gut microbiota plays a significant role in neurogenesis, mental and cognitive development, emotions, and behaviors, and in the progression of neuropsychiatric illnesses. Gut microbiota produces important biologic products that, through the gut-brain axis, are directly connected with the appearance and evolution of neurological and psychiatric disorders such as depression, anxiety, bipolar disorder, autism, schizophrenia, Parkinson’s disease, Alzheimer’s disease, dementia, multiple sclerosis, and epilepsy. This study reviews recent research on the link between gut microbiota and the brain, and microbiome’s role in shaping the development of the most common neurological and psychiatric illnesses. Moreover, special attention is paid to the use of probiotic formulations as a potential non-invasive therapeutic opportunity for prevention and management of neuropsychiatric-associated affections.

Examining weekly relationships between obsessive-compulsive and eating disorder symptoms

BACKGROUND

Despite the severity and high rate of co-occurrence between eating disorders (ED) and obsessive-compulsive disorder (OCD), less is known regarding the longitudinal sequencing of their comorbidity and whether and how their symptoms may influence one another over time. The current study sought to answer these questions by testing if a bidirectional, longitudinal relationship exists between ED symptoms and OCD obsessions and compulsions.

METHODS

We examined the relationship between ED symptoms, obsessions and compulsions across five time points, each one week apart using auto-regressive cross-lagged panel modeling. The final sample consisted of 358 individuals from the community with moderate levels of ED and OCD symptoms, the majority of whom identified as White and male.

RESULTS

Bivariate correlations revealed that ED symptoms, obsessions and compulsions were associated with one another across the five weeks. Two cross-lagged panel models indicated that ED symptoms predicted OCD symptoms at numerous time points and vice versa. However, we found this significant longitudinal associations across only certain weeks. Notably, the models found that only ED symptoms and OCD obsessions predicted one another across different time points across the five weeks; ED symptoms and OCD compulsions did not predict one another.

LIMITATIONS

Due to the non-clinical nature of the sample, there is limited generalizability to clinical populations.

CONCLUSIONS

Our results provide preliminary evidence that there is a bidirectional, longitudinal relationship between ED symptoms and OCD symptoms among a community sample, particularly with respect to cognitive as opposed to behavioral symptoms.

A Longitudinal Magnetoencephalographic Study of the Effects of Deep Brain Stimulation on Neuronal Dynamics in Severe Anorexia Nervosa

Anorexia Nervosa (AN) is a debilitating psychiatric disorder characterized by the relentless pursuit of thinness, leading to severe emaciation. Magnetoencephalography (MEG)was used to record the neuronal response in seven patients with treatment-resistant AN while completing a disorder-relevant food wanting task. The patients underwent a 15-month protocol, where MEG scans were conducted pre-operatively, post-operatively prior to deep brain stimulation (DBS) switch on, twice during a blind on/off month and at protocol end. Electrodes were implanted bilaterally into the nucleus accumbens with stimulation at the anterior limb of the internal capsule using rechargeable implantable pulse generators. Three patients met criteria as responders at 12 months of stimulation, showing reductions of eating disorder psychopathology of over 35%. An increase in alpha power, as well as evoked power at latencies typically associated with visual processing, working memory, and contextual integration was observed in ON compared to OFF sessions across all seven patients. Moreover, an increase in evoked power at P600-like latencies as well as an increase in γ-band phase-locking over anterior-to-posterior regions were observed for high- compared to low-calorie food image only in ON sessions. These findings indicate that DBS modulates neuronal process in regions far outside the stimulation target site and at latencies possibly reflecting task specific processing, thereby providing further evidence that deep brain stimulation can play a role in the treatment of otherwise intractable psychiatric disorders.

Cognitive and Experienced Flexibility in Patients With Anorexia Nervosa and Obsessive Compulsive Disorder

OBJECTIVE

Anorexia nervosa (AN) and obsessive-compulsive disorder (OCD) share a neuropsychological profile characterized by cognitive inflexibility as evident in set-shifting problems, and by strong detail focus. Clinically, both patient groups display a strong rigidity which may be explained by these neurocognitive difficulties. Cognitive inflexibility may hinder treatment uptake and help explain suboptimal treatment outcomes in both AN and OCD. This is the first study to compare clinical AN and OCD groups andto examine similarities and differences in cognitive flexibility. Specifically, this study aims to investigate neuropsychological outcomes and self-reported difficulties in both clinical groups and a control group, and explore associations between the different flexibility outcomes and illness.

METHOD

Two hundred participants (61 AN, 72 OCD and 67 HC) performed neuropsychological tasks on set-shifting abilities (Trail Making Task, Stroop color-word interference, Intradimensional-Extradimensional shift task), detail focus (Group Embedded Figures Test) and self-reported set-shifting abilities and attention to detail (DFlex).

RESULTS

Similarities between patient groups were found in terms of reduced set-shifting ability on the Trail Making Task and detail focus. Moreover, both patient groups self-reported more set-shifting problems but a less strong detail focus than HC, which in turn were not related to neuropsychological task outcomes in either of the groups. In both patient groups longer illness duration was associated to longer reaction times in the switching tasks and for both groups symptom severity was associated to higher experienced inflexibility and attention to detail.

CONCLUSION

Cognitive inflexibility processes are largely similar in patients with AN and OCD. Both patient groups report inflexibility, yet this is unrelated to neuropsychological outcomes. Illness duration seems to contribute to poorer set-shifting and higher illness severity is linked to more experienced inflexibility. Findings highlight the need for entangling different domains of cognitive flexibility and detail focus and examining self-report measures for a cohesive understanding of clinically relevant flexibility weaknesses in AN and OCD.

Suppression of Corticostriatal Circuit Activity Improves Cognitive Flexibility and Prevents Body Weight Loss in Activity-Based Anorexia in Rats

BACKGROUND

The ability to adapt behavior to changing environmental circumstances, or cognitive flexibility, is impaired in multiple psychiatric conditions, including anorexia nervosa (AN). Exaggerated prefrontal cortical activity likely underpins the inflexible thinking and rigid behaviors exhibited by patients with AN. A better understanding of the neural basis of cognitive flexibility is necessary to enable treatment approaches that may target impaired executive control.

METHODS

Utilizing the activity-based anorexia (ABA) model and touchscreen operant learning paradigms, we investigated the neurobiological link between pathological weight loss and cognitive flexibility. We used pathway-specific chemogenetics to selectively modulate activity in neurons of the medial prefrontal cortex (mPFC) projecting to the nucleus accumbens shell (AcbSh) in female Sprague Dawley rats.

RESULTS

DREADD (designer receptor exclusively activated by designer drugs)-based inhibition of the mPFC-AcbSh pathway prevented weight loss in ABA and improved flexibility during early reversal learning by reducing perseverative responding. Modulation of activity within the mPFC-AcbSh pathway had no effect on running, locomotor activity, or feeding under ad libitum conditions, indicating the specific involvement of this circuit in conditions of dysregulated reward.

CONCLUSIONS

Parallel attenuation of weight loss in ABA and improvement of cognitive flexibility following suppression of mPFC-AcbSh activity align with the relationship between disrupted prefrontal function and cognitive rigidity in AN patients. The identification of a neurobiological correlate between cognitive flexibility and pathological weight loss provides a unique insight into the executive control of feeding behavior. It also highlights the utility of the ABA model for understanding the biological bases of cognitive deficits in AN and provides context for new treatment strategies.

A Multi-Faceted Evaluation of Impulsivity Traits and Early Maladaptive Schemas in Patients with Anorexia Nervosa

(1) Background: patients with Anorexia Nervosa (AN) are classified either as restrictive (ANr) or binge/purge (ANbp) according to the absence or presence of impulsive eating and compensatory behaviors. The aim of the present study was to assess the levels of impulsivity in both AN subtypes and to explore whether individual differences in impulsivity may be explained by differences in the presence of early maladaptive schemas. (2) Methods: the sample group included 122 patients with ANr, 112 patients with ANbp, and 131 healthy women (HW). All of these participants completed the UPPS-P scale for an assessment of impulsive behaviors and the Young Schema Questionnaire (YSQ-S3) for an assessment of early maladaptive schemas. (3) Results: the patients with ANbp displayed higher levels of impulsivity compared with the patients with ANr and HW. Patients with AN, especially the restrictive subtype, also reported higher levels of early maladaptive schemas than HW, and regression analyses revealed that specific maladaptive schemas partially explain the variability in impulsivity in both patients and HW. (4) Conclusions: it appears that maladaptive beliefs developed during childhood or adolescence may predict the development of impulsivity, a personality trait usually associated with maladaptive behaviors, and appears to be prevalent among ANbp patients. The clinical effects of this, as well as directions for future study, are also discussed in this paper.

The prevalence of substance use disorders and substance use in anorexia nervosa: a systematic review and meta-analysis

AIM

Individuals with anorexia nervosa (AN) often present with substance use and substance use disorders (SUDs). However, the prevalence of substance use and SUDs in AN has not been studied in-depth, especially the differences in the prevalence of SUDs between AN types [e.g., AN-R (restrictive type) and AN-BP (binge-eating/purge type]. Therefore, this systematic review and meta-analysis aimed to assess the prevalence of SUDs and substance use in AN samples.

METHOD

Systematic database searches of the peer-reviewed literature were conducted in the following online databases: MEDLINE, PsycINFO, Embase, and CINAHL from inception to January 2021. We restricted review eligibility to peer-reviewed research studies reporting the prevalence for either SUDs or substance use in individuals with AN. Random-effects meta-analyses using Freeman-Tukey double arcsine transformations were performed on eligible studies to estimate pooled proportions and 95% confidence intervals (CIs).

RESULTS

Fifty-two studies met the inclusion criteria, including 14,695 individuals identified as having AN (mean age: 22.82 years). Random pooled estimates showed that substance use disorders had a 16% prevalence in those with AN (AN-BP = 18% vs. AN-R = 7%). Drug abuse/dependence disorders had a prevalence of 7% in AN (AN-BP = 9% vs. AN-R = 5%). In studies that looked at specific abuse/dependence disorders, there was a 10% prevalence of alcohol abuse/dependence in AN (AN-BP = 15% vs. AN-R = 3%) and a 6% prevalence of cannabis abuse/dependence (AN-BP = 4% vs. AN-R = 0%). In addition, in terms of substance use, there was a 37% prevalence for caffeine use, 29% prevalence for alcohol use, 25% for tobacco use, and 14% for cannabis use in individuals with AN.

CONCLUSION

This is the most comprehensive meta-analysis on the comorbid prevalence of SUDs and substance use in persons with AN, with an overall pooled prevalence of 16%. Comorbid SUDs, including drugs, alcohol, and cannabis, were all more common in AN-BP compared to AN-R throughout. Therefore, clinicians should be aware of the high prevalence of SUD comorbidity and substance use in individuals with AN. Finally, clinicians should consider screening for SUDs and integrating treatments that target SUDs in individuals with AN. Individuals with anorexia nervosa (AN) may also present with substance use or have a substance use disorder (SUDs). Thus, we conducted a systematic review and meta-analysis to determine the prevalence of substance use and substance use disorders in individuals with AN. We examined published studies that reported the prevalence of either substance use or SUDs in individuals with AN. We found that substance use disorders had a 16% prevalence and that drug abuse/dependence disorders had a prevalence of 7% in those with AN. These rates were much higher in individuals with binge-eating/purging type compared to the restrictive AN. However, many specific substance use disorders and substance use types were low in individuals with AN. Nonetheless, clinicians should be aware of the high prevalence of SUD comorbidity and substance use in individuals with AN.

Fear and food: Anxiety-like behavior and the susceptibility to weight loss in an activity-based anorexia rat model

Anorexia nervosa (AN) is a severe psychiatric disorder characterized by energy restriction, low body weight, a fear of gaining weight, and often excessive physical activity. Anxiety disorders appear to constitute a major risk factor for developing AN and are the most frequent comorbidity. Here, the influence of anxiety‐like behavior prior to food restriction on increased physical activity, leading to greater susceptibility to weight loss, was tested in rats. Furthermore, the possible anxiolytic effect of starvation itself was analyzed. A chronic starvation model activity‐based anorexia (ABA) was applied to mimic physiological and behavioral characteristics of AN. During the induction of starvation and acute starvation, food intake was reduced by 70% and the rats lost 25% of their body weight, which was kept stable to imitate chronic starvation. Anxiety‐like behavior was quantified before and after chronic starvation using the elevated plus maze, based on rodents’ aversion to open spaces. Anxiety‐related behavior before food restriction was associated with increased running‐wheel activity during habituation and during the induction of starvation, and predicted faster weight loss in ABA rats. Additionally, food‐restricted animals showed less anxiety‐like behavior after chronic starvation. Animals showing more anxiety‐like behavior appear to be more susceptible to weight loss, partially mediated by increased physical activity. Anxiety‐related behavior was associated with increased physical activity, which in turn was associated with more rapid weight loss. Our data let us assume that food restriction has an anxiolytic effect. These findings demonstrate the importance of considering anxiety disorders in patients with AN.

The Association of Obsessive-Compulsive Disorder, Anxiety Disorders, and Posttraumatic Stress Disorder with Impairment Related to Eating Pathology

Prior work has shown a number of similarities between obsessive-compulsive disorder (OCD) and eating disorders such as perfectionism and depressive symptoms. However, distress and impairment due to eating pathology are also highly comorbid with other disorders, which brings into question whether the relationship with eating pathology is unique to OCD. The aims of the current study were 1) to test perfectionism and depression as mediators of the relationship between OCD and eating pathology, and 2) to determine whether OCD is related to greater distress/impairment regarding eating habits, exercising, or feelings about eating, shape, or weight above and beyond other disorders. Symptoms were assessed in 329 treatment-seeking patients in a secondary analysis of a clinical battery. The results showed that depressive symptoms and perfectionism were found to mediate the relationship between OCD and eating pathology. Additionally, a regression analysis showed that OCD, social anxiety disorder, and panic disorder symptoms were associated with eating pathology to a greater extent than other disorders. These results suggest that distress and impairment related to eating habits, exercising, or feelings about eating, shape, or weight are not unique to OCD and that depression and perfectionism may, in part, explain the association between OCD and eating pathology.

Disorder specific rewarding stimuli in anorexia nervosa

OBJECTIVE

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

METHOD

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

RESULTS

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

DISCUSSION

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

Cognitive Remediation Therapy Does Not Enhance Treatment Effect in Obsessive-Compulsive Disorder and Anorexia Nervosa: A Randomized Controlled Trial

BACKGROUND

Guideline-recommended therapies are moderately successful in the treatment of obsessive-compulsive disorder (OCD) and anorexia nervosa (AN), leaving room for improvement. Cognitive inflexibility, a common trait in both disorders, is likely to prevent patients from engaging in treatment and from fully benefiting from existing therapies. Cognitive remediation therapy (CRT) is a practical augmentation intervention aimed at ameliorating this impairing cognitive style prior to disorder-specific therapy.

OBJECTIVE

To compare the effectiveness of CRT and a control treatment that was not aimed at enhancing flexibility, named specialized attention therapy (SAT), as add-ons to treatment as usual (TAU).

METHODS

In a randomized controlled multicenter clinical trial, 71 adult patients with OCD and 61 with AN were randomized to ten twice-weekly sessions with either CRT or SAT, followed by TAU. Patients were evaluated at baseline, post-CRT/SAT, and after 6 and 12 months, with outcomes being quantified using the Yale-Brown Obsessive Compulsive Scale for OCD and the Eating Disorder Examination Questionnaire for AN.

RESULTS

Across study groups, most importantly CRT+TAU was not superior to control treatment (SAT)+TAU in reducing OCD and AN pathology. Contrary to expectations, SAT+TAU may have been more effective than CRT+TAU in patients being treated for OCD.

CONCLUSIONS

CRT did not enhance the effect of TAU for OCD and AN more than SAT. Unexpectedly, SAT, the control condition, may have had an augmentation effect on TAU in OCD patients. Although this latter finding may have been due to chance, the effect of SAT delivered as a pretreatment add-on intervention for adults with OCD and AN merits future efforts at replication.

Commentary on Vulnerability and Resilience to Activity-Based Anorexia and the Role of Dopamine

Activity-based anorexia (ABA) is a commonly used rodent model of anorexia nervosa that is based on observations made in rats decades ago. In recently published work, we describe using this paradigm to model vulnerability and resilience to anorexia nervosa in mice, where vulnerability is characterized by hyperactivity and life-threatening weight loss and resilience is characterized by adaptation and weight stabilization. Using genetically modified hyperdopaminergic mice, we also demonstrate that increased dopamine augments vulnerability to ABA. Here, we briefly review our findings and discuss how obtaining vulnerable and resilient phenotypes enhances utility of the ABA model for understanding the neurobiological basis of anorexia nervosa. We comment on our dopamine findings and close by discussing implications for clinical treatment.

Cholinergic dysfunction in the dorsal striatum promotes habit formation and maladaptive eating

Dysregulation of habit formation has been recently proposed as pivotal to eating disorders. Here, we report that a subset of patients suffering from restrictive anorexia nervosa have enhanced habit formation compared with healthy controls. Habit formation is modulated by striatal cholinergic interneurons. These interneurons express vesicular transporters for acetylcholine (VAChT) and glutamate (VGLUT3) and use acetylcholine/glutamate cotransmission to regulate striatal functions. Using mice with genetically silenced VAChT (VAChT conditional KO, VAChTcKO) or VGLUT3 (VGLUT3cKO), we investigated the roles that acetylcholine and glutamate released by cholinergic interneurons play in habit formation and maladaptive eating. Silencing glutamate favored goal-directed behaviors and had no impact on eating behavior. In contrast, VAChTcKO mice were more prone to habits and maladaptive eating. Specific deletion of VAChT in the dorsomedial striatum of adult mice was sufficient to phenocopy maladaptive eating behaviors of VAChTcKO mice. Interestingly, VAChTcKO mice had reduced dopamine release in the dorsomedial striatum but not in the dorsolateral striatum. The dysfunctional eating behavior of VAChTcKO mice was alleviated by donepezil and by l-DOPA, confirming an acetylcholine/dopamine deficit. Our study reveals that loss of acetylcholine leads to a dopamine imbalance in striatal compartments, thereby promoting habits and vulnerability to maladaptive eating in mice.

Eating disorders with over-exercise: A cross-sectional analysis of the mediational role of problematic usage of the internet in young people

Eating disorders are widespread illnesses with significant global impact. There is growing concern about how young people overuse online resources leading to mental health sequelae. We gathered data from 639 individuals from a population cohort. Participants were all young adults at the point of contact and were grouped as having probable eating disorder with excessive exercise (n = 37) or controls (n = 602). We measured obsessionality, compulsivity, impulsivity, and problematic internet use. Group differences in these domains were evaluated; and structural equation modelling (SEM) was used to assess structural relationships between variables. Cases had higher scores of obsessional thoughts of threat (Cohen's d = 0.94, p < 0.001), intolerance towards uncertainty (Cohen's d = 0.72; p < 0.001), thoughts of importance and control (Cohen's d = 0.65, p < 0.01), compulsivity (Cohen's d = 0.72; p < 0.001), negative urgency (Cohen's d = 0.75, p < 0.001), and higher problematic usage of the internet (Cohen's d = 0.73; p-corrected <0.001). Our SEM showed significant partial mediation of problematic internet use on both the effect of obsessionality latent factor on cases (z-value = 2.52, p < 0.05), as well as of sensation seeking latent factor on cases (z-value = 2.09, p < 0.05). Youth with eating disorder and heightened exercise levels have increased obsessive thoughts of threat, compulsivity traits and sensation seeking impulsivity. The association between obsessive thoughts and eating disorders, as well as sensation seeking and eating disorders were partially mediated by problematic internet use. Problematic internet use may be playing a role in the development or maintenance of eating disorder symptoms in the background of obsessional thoughts and sensation seeking impulsive traits.

Trans-diagnostic measurement of impulsivity and compulsivity: A review of self-report tools

INTRODUCTION

Impulsivity and compulsivity are important constructs, relevant to understanding behaviour in the general population, as well as in particular mental disorders (e.g. attention deficit hyperactivity disorder, obsessive-compulsive disorder). The current paper provides a narrative review of self-report impulsivity and compulsivity scales.

METHODS

A literature search was conducted using the following terms: ("impulsivity" OR "compulsivity") AND ("self-report" OR "questionnaire" OR "psychometric" OR "scale").

RESULTS

25 impulsive and 11 compulsive scales were identified, which varied considerably in psychometric properties, convenience, and validity. For impulsivity, the most commonly used scales were the BIS and the UPPS-P, whilst for compulsivity, the Padua Inventory was commonly used. The majority of compulsivity scales measured OCD symptoms (obsessions and compulsions) rather than being trans-diagnostic or specific to compulsivity (as opposed to obsessions). Scales capable of overcoming these limitations were highlighted.

DISCUSSION

This review provides clarity regarding relative advantages and disadvantages of different scales relevant to the measurement of impulsivity and compulsivity in many contexts. Areas for further research and refinement are highlighted.

Discrete Roles for Impulsivity and Compulsivity in Gambling Disorder

Background and Objective: Complex associations between gambling disorder (GD) and impulsivity have been identified. However, little is known regarding how compulsivity associates with different impulsivity domains in GD. In this study, we examined associations between self-reported and behavioral measures of impulsivity-assessed through the Barratt Impulsiveness Scale (BIS-11) and the Experiential Discounting Task (EDT), respectively- and compulsivity-measured using the Padua Inventory and the Wisconsin Card Sorting Test (WCST), respectively-, in an adult sample with GD (N = 132, 94 men and 38 women, ages ranging from 18 to 69 years). GD severity was assessed using the South Oaks Gambling Screen. Methods: Structural Equation Modeling was used to examine relationships between impulsivity and compulsivity measures, age, and GD severity. Results: BIS-11 non-planning and BIS-11 total scores positively correlated with GD severity. The standardized coefficients for the SEM showed direct positive contributions of BIS-11 non-planning, Padua and EDT scores to GD severity. Only participants' ages directly contributed to WCST perseverative errors, and no direct or indirect effects were found with respect to GD severity. Conclusion: The findings suggest that specific aspects of impulsivity and compulsivity contribute to GD severity. Interventions specifically targeting domains that are most relevant to GD severity may improve treatment outcomes.

Binge Eating and Addictive-Like Behaviours in Males and Females

INTRODUCTION

Binge eating is a common behaviour that is strongly linked to both obesity and eating disorder. There is evidence that binge eating commonly co-occurs with other problematic and addictive-like behaviours; however, this has not been explored systematically. The present study aimed to examine the relationship between binge eating, body weight, disordered eating behaviours and associated addictive-like behaviours, with particular attention paid to gender differences.

METHOD

A community sample (N = 500; 75% female, M_age = 32.5 years) reported disordered eating behaviours (i.e. binge eating, purging, restriction of eating, compulsive exercise), body mass index (BMI), food addiction, starvation addiction, exercise dependence, tobacco use and alcohol consumption.

RESULTS

42% of females and 21% of males reported binge eating during the past four weeks. Binge eating was significantly associated with all investigated behaviours in females, and with purging, compulsive exercise and overweight/obesity in males. Controlling for BMI, self-starvation predicted binge eating in males (OR = 1.07), while food addiction (OR = 1.73) and alcohol dependence (OR = 1.11) predicted binge eating in females.

CONCLUSIONS

The multiple associations between binge eating and addictive-like behaviors supports broad screening and generalized prevention efforts. Prevention efforts should reflect gender differences.

FOOD ADDICTION AS A PROXY FOR ANOREXIA NERVOSA SEVERITY: NEW DATA BASED ON THE YALE FOOD ADDICTION SCALE 2.0

The contribution of an addictive process to anorexia nervosa (AN) is an area of growing interest. Yet, little is known about how the food addiction concept (FA) may be of interest in understanding AN. This study investigates prevalence of FA diagnostic and its association with markers of severity in individuals with AN. We conducted a retrospective study in a sample of 73 patients with AN. We assessed FA with the Yale Food Addiction Scale 2.0, depressive and anxiety disorders, impulsivity (Beck Depression Inventory, STAI, BIS-11) and eating behavior (BITE, EDE-Q). Prevalence of FA in our sample was 47%. FA was significantly associated and positively correlated with the binge-eating/purging subtype of AN, higher levels of depression, anxiety and greater eating psychopathology. FA was not associated with level of impulsivity nor leptin and IGF-1 blood levels. The relationship between FA severity and AN severity was mediated by the severity of binge eating behaviors. Our results suggest that the presence of FA may represent a more severe variant of AN. Longitudinal studies are needed to better understand the etiologic process between FA and AN.

Impulsivity and compulsivity in anorexia and bulimia nervosa: A systematic review

This study aimed to systematically appraise cross-sectional research that compared the cognitive performance of individuals in the acute phase of BN and/or AN to HCs on measures of impulsivity and compulsivity. The results of the systematic review showed support for the trans-diagnostic approach to eating disorders. There was no strong evidence to support the characterisation of AN as high in compulsivity (and low in impulsivity), nor to support the characterisation of BN as high in impulsivity (and low in compulsivity). There appeared to be mixed findings for both impulsivity and compulsivity across AN and BN. Results were highly variable due to the heterogeneous tasks used, and lack of replication across studies. There was no consensus amongst the included studies on the most appropriate task and/or outcome measures that should be used to study the constructs of impulsivity and compulsivity.

Targeting all psychopathological dimensions in the treatment of anorexia nervosa

Efforts to improve the prognosis of subjects with anorexia nervosa [AN] through the development of specific therapeutic interventions have yielded unsatisfactory results. AN can be perceived as a mental disorder that is clinically composed of disturbed psychopathological dimensions found in major depressive disorder, obsessive compulsive disorder, body dysmorphic disorder, and delusional disorder somatic type. Future treatment strategies of patients with AN might target these multiple psychopathological dimensions. Considering that each of these dimensions is known to be best treated with psychopharmacologic drugs such as antidepressants, mood stabilizers and antipsychotic drugs, AN treatment guidelines may need to consider prescribing them to patients.

The effect of repetitive transcranial magnetic stimulation on food choice-related self-control in patients with severe, enduring anorexia nervosa

OBJECTIVE

Individuals with anorexia nervosa (AN) pursue low-fat, low-calorie diets even when in a state of emaciation. These maladaptive food choices may involve fronto-limbic circuitry associated with cognitive control, habit, and reward. We assessed whether high-frequency repetitive transcranial magnetic stimulation (rTMS) to the left dorsolateral prefrontal cortex (DLPFC) influenced food-related choice behavior in patients with severe, enduring (SE)-AN.

METHOD

Thirty-four females with SE-AN completed a Food Choice Task before and after 20 sessions of real or sham rTMS treatment and at a 4-month follow-up. During the task, participants rated high- and low-fat food items for healthiness and tastiness and then made a series of choices between a neutral-rated food and high- and low-fat foods. Outcomes included the proportion of high-fat and self-controlled choices made. A comparison group of 30 healthy women completed the task at baseline only.

RESULTS

Baseline data were consistent with previous findings: relative to healthy controls, SE-AN participants showed a preference for low-fat foods and exercised self-control on a greater proportion of trials. There was no significant effect of rTMS treatment nor time on food choices related to fat content. However, among SE-AN participants who received real rTMS, there was a decrease in self-controlled food choices at post-treatment, relative to baseline. Specifically, there was an increase in the selection of tasty-unhealthy foods.

DISCUSSION

In SE-AN, rTMS may promote more flexibility in relation to food choice. This may result from neuroplastic changes in the DLPFC and/or in associated brain areas.

Predicting the restrictive eating, exercise, and weight monitoring compulsions of anorexia nervosa

PURPOSE

Compulsions surrounding restrictive eating, exercise, and weight monitoring are thought to maintain abnormal eating behaviour in individuals with anorexia nervosa (AN). This study aimed to determine if AN psychopathology and trait anxiety explain the presence of restrictive eating, exercise, and weight monitoring compulsions in a mixed sample.

METHODS

Participants were 31 females with AN and 31 age and gender-matched healthy individuals (HC). Restrictive eating, exercise and weight monitoring compulsion presence was compared between AN and HC groups. Multivariable poisson regression analyses, adjusted for diagnostic status, were conducted to assess the association of both AN psychopathology and trait anxiety with compulsions across the mixed group.

RESULTS

Individuals with AN endorsed a greater number of restrictive eating, exercise and weight monitoring compulsions compared to HC. In adjusted poisson regression analyses neither AN psychopathology nor trait anxiety predicted compulsion presence: incidence rate ratio (IRR) for AN psychopathology = 1.15 [95% CI 0.84, 1.57], p = 0.39; IRR for trait anxiety = 1.01 [95% CI 0.97, 1.06], p = 0.50.

CONCLUSIONS

Greater presence of restrictive eating, exercise and weight monitoring compulsions was reported by individuals with AN, supporting the conceptualisation of disorder behaviours as compulsive. The study was underpowered to robustly evaluate the association between predictors of interest and the compulsions outcome, largely owing to the small sample size. Further investigation is required, ideally using methods able to identify causal and mediation effects.

LEVEL OF EVIDENCE

Level V, cross-sectional study.

Self-directed behaviors differentially explain associations between emotion dysregulation and eating disorder psychopathology in patients with or without objective binge-eating

BACKGROUND

Emotion dysregulation and negative self-directed behaviors are key characteristics of eating disorders (EDs), but their interaction in relation to ED psychopathology is insufficiently explored, and empirically robust and clinically relevant models are needed.

METHODS

This study examined whether the association between emotion dysregulation and ED psychopathology was mediated by different negative self-directed behaviors in 999 ED patients divided into two sub-samples based on absence or presence of objective binge-eating episodes (OBE). Several simple and extended mediation models were examined using the Difficulties in Emotion Regulation Scale (DERS) as independent variable, the Structural Analysis of Social Behavior (SASB) as mediator, and the Eating Disorder Examination Questionnaire (EDE-Q) as dependent variable.

RESULTS

An associational pathway was found where higher emotion dysregulation was associated with more negative self-directed behaviors, which in turn was associated with higher ED psychopathology. Self-directed behaviors of importance differed between patient groups. In participants without OBE, lower self-love and higher self-attack were influential, whereas in participants with OBE, lower self-affirmation and higher self-blame were influential.

CONCLUSIONS

Self-directed behaviors may help to explain the association between emotion dysregulation and ED psychopathology. Our findings have both theoretical and clinical implications that are pathology-specific. Addressing specific self-directed behaviors could be an important way of helping patients deal with their emotions in relation to ED psychopathology.

Habits are stronger with longer duration of illness and greater severity in anorexia nervosa

OBJECTIVE

The aim of this study was to examine the relationship between habit strength and clinical features of anorexia nervosa (AN). Habit strength, separate from intention, relates to the persistence of behavior, and is measured by the Self-Report Habit Index (SRHI). We hypothesized that habit strength would be greater among individuals with AN than healthy controls (HC) and that habit strength would be associated with duration and severity of illness.

METHOD

Participants were 116 women with AN (n = 69) and HC (n = 47) who completed the SRHI, the Eating Disorder Examination-Questionnaire (EDE-Q), and a multi-item laboratory meal. The SRHI assessed four domains and these subscales were averaged for the total score.

RESULTS

Individuals with AN demonstrated significantly greater habit strength than HC in the total score (t₁₁₄ = 7.00, p < .01), and within each domain (restrictive eating, compensatory behavior, delay of eating, and rituals). Total SRHI score was significantly associated with EDE-Q scores for both AN and HC groups (r_AN = .59, p_AN = <.001; r_HC = .32, p_HC = .030). Among patients, there was a significant association between SRHI and duration of illness (r = .38, p = .001). There was no significant association between SRHI and caloric intake (r_AN = -.20, p_AN = .10; r_HC = -.25, p_HC = .09).

DISCUSSION

Habit strength was related to chronicity and severity of AN, suggesting that habit formation may play an important role in illness. These data suggest avenues for mechanism research and treatment development.

Dopaminergic activity and exercise behavior in anorexia nervosa

Driven exercise (i.e., the tendency to exercise in excess to influence weight/shape or regulate emotion) is difficult to manage in the context of anorexia nervosa, and is associated with poorer treatment outcomes, and psychological and medical severity. Driven exercise is observed in a considerable number of those diagnosed with anorexia nervosa; however, to date, this hallmark symptom remains poorly understood. Dopamine signaling is implicated in motivating and maintaining appetitive behavior among patients with eating disorders; but, much less is known about the role of dopamine signaling specific to the symptom of driven exercise. An improved understanding of this biobehavioral mechanism may inform the etiology of driven exercise in anorexia nervosa, with the potential to impact future research and treatment efforts. This review describes the role that dopamine serves in maintaining symptoms in the context of anorexia nervosa, and synthesizes current relevant evidence on exercise in AN and related dopaminergic activity. Throughout, theoretical implications are discussed, along with critical directions for future research.

Trapped in a Glass Bell Jar: Neural Correlates of Depersonalization and Derealization in Subjects at Clinical High-Risk of Psychosis and Depersonalization-Derealization Disorder

BACKGROUND

Depersonalization (DP) and derealization (DR) are symptoms of a disruption of perceptual integration leading to an altered quality of subjective experiences such as feelings of unreality and detachment from the self (DP) or the surroundings (DR). Both DP and DR often occur in concert with other symptoms, for example in subjects at clinical high-risk (CHR) for psychosis, but also appear isolated in the form of DP/DR disorder. Despite evidence that DP/DR causes immense distress, little is known about their neurobiological underpinnings. Therefore, we investigated the neural correlates of DP/DR using pseudo-continuous arterial spin labeling MRI.

METHODS

We evaluated the frequency of DP/DR symptoms in a clinical sample (N = 217) of help-seeking individuals from the Early Detection and Intervention Centre for Mental Crisis (CHR, n = 97; clinical controls (CC), n = 91; and first-episode psychosis (FEP), n = 29). Further, in a subsample of those CHR subjects who underwent MRI, we investigated the resting-state regional cerebral blood flow (rCBF). Here, individuals with (n = 21) and without (n = 23) DP/DR were contrasted. Finally, rCBF was measured in a small independent second sample of patients with DP/DR disorder (n = 6) and healthy controls (HC, n = 6).

RESULTS

In the complete clinical sample, significantly higher frequency of DP/DR was found in CHR compared to CC (50.5 vs. 16.5%; χ² ₍₂₎ = 24.218, p ≤ 0.001, Cramer's V = 0.359) as well as in FEP compared to CC (37.9 vs. 16.5%; χ² ₍₂₎ = 5.960, p = 0.015, Cramer's V = 0.223). In MRI, significantly lower rCBF was detected in the left orbitofrontal cortex in CHR with vs. without DP/DR (x/y/z = -16/42/-22, p < 0.05, FWE corrected). In patients with DP/DR disorder, significantly higher rCBF was detected in the left caudate nucleus (x/y/z = -18/-32/18, p < 0.05) compared to HC.

CONCLUSIONS

This study shows that DP/DR symptoms are frequently found in CHR subjects. Investigating two separate DP/DR populations with an identical neuroimaging technique, our study also indicates that there may be divergent pathophysiological mechanisms-decreased neuronal activity in the orbitofrontal cortex, but increased activity within the caudate nucleus-leading to a final common pathway with similar psychopathological symptoms. This suggests that both top-down (orbitofrontal cortex) and bottom-up (caudate nucleus) mechanisms could contribute to the emergence of DP/DR.