From disordered eating to addiction: the "food drug" in bulimia nervosa

Role of Endogenous Opioids in the Pathophysiology of Obesity and Eating Disorders

This second chapter in our trilogy reviews and critically appraises the scientific evidence for the role of endogenous opioid system (EOS) activity in the onset and progression of both obesity and eating disorders. Defining features of normative eating and maladaptive eating behaviors are discussed as a foundation. We review the scientific literature pertaining to the predisposing risk factors and pathophysiology for obesity and eating disorders. Research targeting the association between obesity, disordered eating, and psychiatric comorbidities is reviewed. We conclude by discussing the involvement of endogenous opioids in neurobiological and behavior traits, and the clinical evidence for the role of the EOS in obesity and eating disorders.

Iatrogenic triggers for anorexia nervosa and bulimia nervosa: A WHO safety database disproportionality analysis

Eating disorders, characterized by abnormal eating, weight control behaviors or both include anorexia nervosa (AN) and bulimia nervosa (BN). We investigated their potential iatrogenic triggers, using real-world data from the WHO safety database (VigiBase®). VigiBase® was queried for all AN and BN reports. The reports were classified as `pediatric' or `adult' according to age. Disproportionality analyses relied on the Information Component (IC), in which a 95% confidence interval lower-end positivity was required to suspect a signal. Our queries yielded 309 AN and 499 BN reports. Isotretinoin was disproportionately reported in pediatric AN (IC 3.6; [2.6-4.3]), adult AN (IC 3.1; [1.7-4.0]), and pediatric BN (IC 3.9; [3.0-4.7]). Lamivudine (IC 4.2; [3.2-4.9]), nevirapine (IC 3.7; [2.6-4.6]), and zidovudine (IC 3.4; [2.0-4.3]) had the highest ICs in adult AN. AN was associated with isotretinoin, anticonvulsants in minors, and antiretroviral drugs in adults. In adults, BN was related to psychotropic and hormonally active drugs. Before treatment initiation, an anamnesis should seek out mental health conditions, allowing the identification of patients at risk of developing or relapsing into AN or BN. In addition to misuse, the hypothesis of iatrogenic triggers for AN and BN should also be considered.

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.

Disentangling binge eating disorder and food addiction: a systematic review and meta-analysis

BACKGROUND AND AIMS

The concept of "Food Addiction" has been based on criteria of Substance Use Disorder. Several studies suggested a relationship between food addiction and eating disorders, but little is known about its extent or role. We aim at exploring if food addiction is coincident with a specific eating disorder (binge eating disorder appears the closest) or it is a separate diagnostic entity that afflicts in comorbidity with eating disorders or other conditions like obesity or even in the general population.

METHODS

This systematic review and meta-analysis analyzed observational studies with a comparative estimation on rates of subjects affected by binge eating disorder and food addiction.

RESULTS

Binge eating disorder shows higher comorbidity with food addiction compared to other eating disorders (OR = 1.33, 95% CI, 0.64-2.76; c² = 4.42; p = 0.44;I² = 0%), or each eating disorder [anorexia nervosa purging type (OR = 1.93, 95% CI, 0.20-18.92; p = 0.57) and restrictive type (OR = 8.75, 95% CI, 1.08-70.70; p = 0.04)], obese patients (OR = 5.72, 95% CI, 3.25-10.09; p =  < 0.0001) and individuals from the general population (OR = 55.41, 95% CI, 8.16-376.10; c² = 18.50; p < 0.0001; I² = 0%)but has decreased prevalence when compared to bulimia nervosa (OR = 0.85, 95% CI, 0.33-2.22; c² = 0.35; p = 0.74; I² = 0%).

DISCUSSION AND CONCLUSIONS

Our data show that the prevalence of food addiction in binge eating disorder is higher than in other eating disorders except in bulimia nervosa. Moreover, it is a separate diagnostic reality and can be detected in people without mental illness and in the general population. Food addiction might have a prognostic value, since in comorbidity, and should be addressed to boost treatment efficacy and patient's recovery.

LEVEL OF EVIDENCE

I: Evidence obtained systematic reviews and meta-analyses.

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.

The FODRAT study (FOod addiction, DRugs, Alcohol and Tobacco): first data on food addiction prevalence among patients with addiction to drugs, tobacco and alcohol

OBJECTIVES

The main focus of this study was to evaluate the prevalence of food addiction (FA) in a population of 575 subjects, all affected by drugs, alcohol and/or tobacco addiction.

METHODS

Patients were enrolled in Addiction Service Centers and 25 items YFAS questionnaire was administered. Prevalence of FA was studied among patients who already have an addiction and then this prevalence was compared between groups of abusers (by type of substance), comparing mono abusers with polyabusers, as well as regressions by age, BMI, sex, through multiple regression analysis.

RESULTS

Prevalence of FA in the sample is 20.17%. Risk of FA increases with the number of substances used (polyabuse). Results show a positive correlation, in addicted people, between BMI values and FA, with significant values (OR 1.08; 95% CI 1.04-1.13; p = 0.006). Age is inversely correlated with FA (OR 0.97; 95% CI 0.95-0.99; p = 0.01). Female sex is positively associated (OR 2.60; 95% CI 1.59-4.27, p = 0.000). No significant association appears with any substance, even if the highest prevalence is recorded among cannabis users (31.03%), and heroin (21.07%), followed by cocaine (18.53%), alcohol (14.49%) and tobacco (11.61%). A comparison between the FA prevalence in our study and that from another study in the Italian general population (11%) shows a significant difference (p < 0.001).

CONCLUSIONS

Prevalence of FA among addicted people is greater than in the general population. Risk of FA increases with the increase in number of used substances (polyabuse). Age is inversely correlated with FA. There is a positive and significant correlation between BMI and FA among substance/tobacco abusers.

LEVEL OF EVIDENCE

Level V, observational cross-sectional descriptive study.

Validation of the Yale Food Addiction Scale 2.0 in Patients Seeking Bariatric Surgery

BACKGROUND

The Yale Food Addiction Scale (YFAS) was developed in 2009 to assess food addiction (FA); a revised version was released in 2016 (YFAS 2.0). The objective of this study was to determine the statistical and clinical validity of the YFAS 2.0 in adults seeking bariatric surgery.

METHODS

Patients who underwent a preoperative psychological evaluation in preparation for bariatric surgery from 2015 to 2018 were included. The YFAS 2.0 was administered as part of routine clinical care and validated against an assessment battery of standardized clinical measures. Statistical analyses included chi-square and Wilcoxon rank sum tests and calculation of Spearman's rank correlation coefficients.

RESULTS

Overall, 1061 patients were included. Mean age and BMI were 47.5 ± 12.9 years and 46.9 ± 13.4 kg/m², respectively. There were 196 (18%) patients who screened positive on the YFAS 2.0 (21% mild, 23% moderate, and 56% severe FA). The YFAS 2.0 demonstrated strong convergent validity where patients who met criteria for FA had significantly increased levels of binge eating (p < 0.001), emotional eating (p < 0.001), and lower self-efficacy (p < 0.001). Discriminant validity was demonstrated by lack of association with alcohol use (p = 0.319). The YFAS 2.0 was significantly correlated with total scores for depression (p < 0.001), anxiety (p < 0.001), bipolar disorder symptoms (p < 0.001), and trauma history (p < 0.001).

CONCLUSIONS

The prevalence of FA in a large sample of patients seeking bariatric surgery was consistent with previous literature. These data suggest that the YFAS 2.0 is psychometrically valid, demonstrating strong construct validity, and is a clinically useful measure of FA severity in patients pursuing bariatric surgery.

Drunkorexia: Normative behavior or gateway to alcohol and eating pathology?

Drunkorexia is characterized by a group of behaviors designed to minimize caloric intake while maximizing levels of alcohol intoxication. Individuals plan and modify their diet, via skipping meals, exercising, or purging, to save calories for a night of alcohol consumption. Minimal research has examined risk factors related to drunkorexia, and little is known regarding associated problems. We used structural equation modeling to test associations between coping and enhancement motives, drive for thinness, body dissatisfaction, and disordered eating (i.e., bulimia behaviors) and drinking among an at-risk college population (N = 364). Drive for thinness and alcohol coping motives were positively associated with drunkorexia. Notably, drunkorexia was associated with alcohol-related outcomes, but not bulimia. While common risk factors are shared with eating pathology, drunkorexia appears to be a unique construct apart from bulimia behaviors. Results indicate drunkorexia behaviors may extend past normative drinking and place individuals at increased risk of alcohol-related problems. The current study contributes to greater understanding of functional models and maladaptive outcomes related to drunkorexia behaviors.

Food Addiction among Female Patients Seeking Treatment for an Eating Disorder: Prevalence and Associated Factors

The concept of "food addiction" (FA) has aroused much focus because of evidence for similarities between overeating and substance use disorders (SUDs). However, few studies have explored this concept among the broad spectrum of eating disorders (ED), especially in anorexia nervosa (AN). This study aimed to assess FA prevalence in ED female patients and to determine its associated factors. We recruited a total of 195 adult women with EDs from an ED treatment center. The prevalence of FA diagnosis (Yale Food Addiction Scale) in the whole ED sample was 83.6%; AN restrictive type (AN-R), 61.5%; AN binge-eating/purging type (AN-BP), 87.9%; bulimia nervosa (BN), 97.6%; and binge-eating disorder (BED), 93.3%. The most frequently met criteria of FA were "clinically significant impairment or distress in relation to food", "craving" and "persistent desire or repeated unsuccessful attempts to cut down". An FA diagnosis was independently associated with three variables: presence of recurrent episodes of binge eating, ED severity, and lower interoceptive awareness. In showing an overlap between ED and FA, this study allows for considering EDs, and AN-R in particular, from an "addictive point of view", and thus for designing therapeutic management that draws from those proposed for addictive disorders.

Demographic and psychiatric correlates of compulsive sexual behaviors in gambling disorder

BACKGROUND AND AIMS

Gambling disorder (GD) and compulsive sexual behavior (CSB) may commonly co-occur. Yet, the psychiatric correlates of these co-occurring disorders are an untapped area of empirical scrutiny, limiting our understanding of appropriate treatment modalities for this dual-diagnosed population. This study examined the demographic and clinical correlates of CSB in a sample of treatment-seeking individuals with GD (N = 368) in São Paulo, Brazil.

METHODS

Psychiatrists and psychologists conducted semi-structured clinical interviews to identify rates of CSB and other comorbid psychiatric disorders. The Shorter PROMIS Questionnaire was administered to assess additional addictive behaviors. The TCI and BIS-11 were used to assess facets of personality. Demographic and gambling variables were also assessed.

RESULTS

Of the total sample, 24 (6.5%) met diagnostic criteria for comorbid CSB (GD + CSB). Compared to those without compulsive sexual behaviors (GD - CSB), individuals with GD + CSB were more likely to be younger and male. No differences in gambling involvement emerged. Individuals with GD + CSB tended to have higher rates of psychiatric disorders (depression, post-traumatic stress disorder, and bulimia nervosa) and engage in more addictive behaviors (problematic alcohol use, drug use, and exercise) compared to GD - CSB. Those with GD + CSB evidenced less self-directedness, cooperativeness, self-transcendence, and greater motor impulsivity. Logistic regression showed that the predictors of GD + CSB, which remained in the final model, were being male, a diagnosis of bulimia, greater gambling severity, and less self-transcendence.

DISCUSSION AND CONCLUSION

Given those with GD + CSB evidence greater psychopathology, greater attention should be allocated to this often under studied comorbid condition to ensure adequate treatment opportunities.

Sugar Addiction: From Evolution to Revolution

The obesity epidemic has been widely publicized in the media worldwide. Investigators at all levels have been looking for factors that have contributed to the development of this epidemic. Two major theories have been proposed: (1) sedentary lifestyle and (2) variety and ease of inexpensive palatable foods. In the present review, we analyze how nutrients like sugar that are often used to make foods more appealing could also lead to habituation and even in some cases addiction thereby uniquely contributing to the obesity epidemic. We review the evolutionary aspects of feeding and how they have shaped the human brain to function in "survival mode" signaling to "eat as much as you can while you can." This leads to our present understanding of how the dopaminergic system is involved in reward and its functions in hedonistic rewards, like eating of highly palatable foods, and drug addiction. We also review how other neurotransmitters, like acetylcholine, interact in the satiation processes to counteract the dopamine system. Lastly, we analyze the important question of whether there is sufficient empirical evidence of sugar addiction, discussed within the broader context of food addiction.

Drunkorexia: an emerging trend in young adults

OBJECTIVE

Several studies demonstrated an association between alcohol consumption and unhealthy food habits. Particularly, in young adults it has been observed the tendency to use extreme forms of weight control as a way to compensate planned binge drinking.

METHOD

A questionnaire was administered to a sample of 4275 healthy subjects (43.9% males; 56.1% females), aged between 18 and 26 (mean age 22.04). The survey investigated socio-economic characteristics, drinking habits with a specific focus on binge consumption, abnormal eating behaviours and psychoactive substance use.

RESULTS

34.1% of the overall sample reported to limit their calorie intake before drinking, with no significant gender difference. A significant correlation was found between drunkorexic attitudes and, respectively, binge drinking behaviours (p < .01), use of cocaine (p < .01), and use of Novel Psychoactive Substances (p < .01).

DISCUSSION

Our data identified drunkorexia as a common behaviour among Italian young adults. Raising awareness on drunkorexia may help health care providers to timely address and approach its possible short- and long-term consequences.

LEVEL OF EVIDENCE

Level V (descriptive study).

Molecular bases of anorexia nervosa, bulimia nervosa and binge eating disorder: shedding light on the darkness

Eating-disorders (EDs) consequences to human health are devastating, involving social, mental, emotional, physical and life-threatening aspects, concluding on impairment and death in cases of extreme anorexia nervosa. It also implies that people suffering an ED need to find psychiatric and psychological help as soon as possible to achieve a fully physical and emotional recovery. Unfortunately, to date, there is a crucial lack of efficient clinical treatment to these disorders. In this review, we present an overview concerning the actual pharmacological and psychological treatments, the knowledge of cells, circuits, neuropeptides, neuromodulators and hormones in the human brain- and other organs- underlying these disorders, the studies in animal models and, finally, the genetic approaches devoted to face this challenge. We will also discuss the need for new perspectives, avenues and strategies to be developed in order to pave the way to novel and more efficient therapeutics.

Bulimia Nervosa/Purging Disorder

Bulimia nervosa was first described in 1979 by British psychiatrist Gerald Russell as a "chronic phase of anorexia nervosa" in which patients overeat and then use compensatory mechanisms, such as self-induced vomiting, laxatives, or prolonged periods of starvation. The characterization of bulimia nervosa continues to evolve with the introduction of the DSM-5 in 2013. In this article, the epidemiology and risk factors of bulimia nervosa are identified and reviewed, along with the medical complications and psychiatric comorbidities. The evaluation of a patient with suspected bulimia nervosa is addressed, with an emphasis on acquiring a complete and thorough history as well as discovering any comorbidities that are present. Management of the patient involves both medical interventions and behavioral counseling in order to address physical, psychological, and social needs. Lastly, a new diagnosis introduced in the DSM-5, purging disorder, is described and discussed.

Incorporating food addiction into disordered eating: the disordered eating food addiction nutrition guide (DEFANG)

Although not formally recognized by the DSM-5, food addiction (FA) has been well described in the scientific literature. FA has emerged as a clinical entity that is recognized within the spectrum of disordered eating, particularly in patients with bulimia nervosa, binge-eating disorder and/or co-occurring addictive disorders and obesity. Integrating the concept of FA into the scope of disordered eating has been challenging for ED treatment professionals, since there is no well-accepted treatment model. The confusion surrounding the implications of FA, as well as the impact of the contemporary Westernized diet, may contribute to poor treatment outcomes. The purpose of this review is twofold. The first is to briefly explore the relationships between EDs and addictions, and the second is to propose a new model of conceptualizing and treating EDs that incorporates recent data on FA. Since treatment for EDs should vary based on individual assessment and diagnosis, the Disordered Eating Food Addiction Nutrition Guide (DEFANG) is presented as a tool for framing treatment goals and helping patients achieve sustainable recovery.

Errors as a Means of Reducing Impulsive Food Choice

Nowadays, the increasing incidence of eating disorders due to poor self-control has given rise to increased obesity and other chronic weight problems, and ultimately, to reduced life expectancy. The capacity to refrain from automatic responses is usually high in situations in which making errors is highly likely. The protocol described here aims at reducing imprudent preference in women during hypothetical intertemporal choices about appetitive food by associating it with errors. First, participants undergo an error task where two different edible stimuli are associated with two different error likelihoods (high and low). Second, they make intertemporal choices about the two edible stimuli, separately. As a result, this method decreases the discount rate for future amounts of the edible reward that cued higher error likelihood, selectively. This effect is under the influence of the self-reported hunger level. The present protocol demonstrates that errors, well known as motivationally salient events, can induce the recruitment of cognitive control, thus being ultimately useful in reducing impatient choices for edible commodities.

The Relationship Between Eating Disorder Symptoms and Treatment Rejection among Young Adult Men in Residential Substance Use Treatment

Research has demonstrated that individuals with substance use disorders (SUDs) and comorbid mental health problems evidence heightened negative consequences, including poorer treatment outcomes, a higher risk for relapse, and mortality compared to individuals with a single disorder. In this study, we focus on the comorbidity between SUDs and eating disorder (ED) symptomatology, as EDs are similarly associated with high rates of relapse, morbidity, and mortality. Of particular importance is research examining treatment rejection among individuals in treatment for SUDs with cooccurring ED symptomatology. This study seeks to add to the literature by examining treatment rejection among young adult men in residential treatment for SUDs (N = 68) with cooccurring ED symptomatology. Results from hierarchical regression analyses indicated that ED symptoms were significantly associated with treatment rejection after controlling for alcohol and drug use and problems and depression symptoms. Although this is a preliminary study, the results add to a growing body of research examining the comorbidity between SUDs and ED symptomatology. Future research examining this relationship is needed to further elucidate the treatment patterns among individuals with comorbid ED symptoms and substance use diagnoses.

The use of repetitive transcranial magnetic stimulation for modulating craving and addictive behaviours: a critical literature review of efficacy, technical and methodological considerations

OBJECTIVES

Repetitive transcranial magnetic stimulation (rTMS) is a potential therapeutic intervention for the treatment of addiction. This critical review aims to summarise the recent developments with respect to the efficacy of rTMS for all types of addiction and related disorders (including eating disorders), and concentrates on the associated methodological and technical issues.

METHODS

The bibliographic search consisted of a computerised screening of the Medline and ScienceDirect databases up to December 2013. Criteria for inclusion were the target problem was an addiction, a related disorder, or craving; the intervention was performed using rTMS; and the study was a clinical trial.

RESULTS

Of the potential 638 articles, 18 met the criteria for inclusion. Most of these (11 of the 18) supported the efficacy of rTMS, especially in the short term. In most cases, the main assessment criterion was the measurement of craving using a Visual Analogue Scale.

DISCUSSION

The results are discussed with respect to the study limitations and, in particular, the many methodological and technical discrepancies that were identified. Key recommendations are provided.

Eating Disorder Symptoms and Length of Stay in Residential Treatment for Substance Use: A Brief Report

OBJECTIVE

Treatment dropout is common both among people in treatment for eating disorders and for substance use disorders. Because of the high rates of co-occurrence and mortality associated with these disorders, the purpose of the current study was to examine the relationship among eating disorder symptoms, length of stay, and decisions to leave against medical advice among individuals in substance use treatment.

METHODS

We analyzed de-identified medical record data for 122 adult women enrolled in residential treatment for substance use disorders over a 12-month period. Routine treatment intake included standardized assessments of eating disorders, depression, and substance use.

RESULTS

Participants averaged 43.1 years of age (SD = 10.7) and were primarily non-Hispanic Caucasian (n = 118, 96.7%). Approximately 8 (6.6%) patients met criteria for a probable eating disorder and 79 (64.8%) for a probable alcohol use disorder. Mean length of stay was 28.1 days (SD = 6.6) and 21 (17%) patients left against medical advice. Logistic regression analysis showed that eating disorder symptoms were significantly associated with decisions to leave treatment against medical advice after controlling for age, years of education, depression symptoms, alcohol problems, and drug problems: χ(2) = 14.88, df = 6, p =.02. This model accounted for 19.1% (Nagelkerke R(2)) of the variance in discharge type. Eating disorder symptoms were not associated with length of treatment.

CONCLUSIONS

Our findings suggest the importance of assessing and monitoring eating disorder symptoms among individuals in treatment for substance use disorders.

Disulfiram for binge eating disorder: an open trail

OBJECTIVE

To evaluate the efficacy and safety of disulfiram for treatment of binge eating disorder.

METHOD

Two hundred and fifty milligrams per day of disulfiram was administered to 12 patients affected by binge eating disorder for 16 weeks; the number of binge eating episodes per week and the number of participants who reported side effects were evaluated.

RESULTS

Nine participants (75.0%) completed the trial, while the other 3 (25.0%) discontinued prematurely. Disulfiram significantly decreased the mean frequency of binge eating episodes per week from 7.9±1.2 to 0.9±0.6 (p<.001). All patients (100.0%) reduced the frequency of binge eating episodes, and 7 participants (58.3%) achieved remission of binge eating. Eleven participants (91.7%) reported side effects [drowsiness (N=9), headache (N=7), dysgeusia (N=3), tachycardia (N=3), dizziness (N=2), and nausea (N=2)].

DISCUSSION

While disulfiram reduced the frequency of binge eating episodes, side effects were observed in the majority of participants. Longer-term placebo-controlled studies are warranted to exclude the contribution of a placebo response from these results and to evaluate drugs with similar pharmacological activity but improved tolerability.

Errors affect hypothetical intertemporal food choice in women

Growing evidence suggests that the ability to control behavior is enhanced in contexts in which errors are more frequent. Here we investigated whether pairing desirable food with errors could decrease impulsive choice during hypothetical temporal decisions about food. To this end, healthy women performed a Stop-signal task in which one food cue predicted high-error rate, and another food cue predicted low-error rate. Afterwards, we measured participants' intertemporal preferences during decisions between smaller-immediate and larger-delayed amounts of food. We expected reduced sensitivity to smaller-immediate amounts of food associated with high-error rate. Moreover, taking into account that deprivational states affect sensitivity for food, we controlled for participants' hunger. Results showed that pairing food with high-error likelihood decreased temporal discounting. This effect was modulated by hunger, indicating that, the lower the hunger level, the more participants showed reduced impulsive preference for the food previously associated with a high number of errors as compared with the other food. These findings reveal that errors, which are motivationally salient events that recruit cognitive control and drive avoidance learning against error-prone behavior, are effective in reducing impulsive choice for edible outcomes.

Food addiction in the light of DSM-5

The idea that specific kind of foods may have an addiction potential and that some forms of overeating may represent an addicted behavior has been discussed for decades. In recent years, the interest in food addiction is growing and research on this topic lead to more precise definitions and assessment methods. For example, the Yale Food Addiction Scale has been developed for the measurement of addiction-like eating behavior based on the diagnostic criteria for substance dependence of the fourth revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). In 2013, diagnostic criteria for substance abuse and-dependence were merged, thereby increasing the number of symptoms for substance use disorders (SUDs) in the DSM-5. Moreover, gambling disorder is now included along SUDs as a behavioral addiction. Although a plethora of review articles exist that discuss the applicability of the DSM-IV substance dependence criteria to eating behavior, the transferability of the newly added criteria to eating is unknown. Thus, the current article discusses if and how these new criteria may be translated to overeating. Furthermore, it is examined if the new SUD criteria will impact future research on food addiction, for example, if "diagnosing" food addiction should also be adapted by considering all of the new symptoms. Given the critical response to the revisions in DSM-5, we also discuss if the recent approach of Research Domain Criteria can be helpful in evaluating the concept of food addiction.

The association of "food addiction" with disordered eating and body mass index

INTRODUCTION

The contribution of an addictive process to elevated body mass index (BMI) and disordered eating is an area of growing interest. Yet, little is known about how "food addiction" may be related to disordered eating and obesity. The ability of addictive-like eating to account for eating pathology not captured by traditional eating disorders is unknown. No prior research has examined the association of "food addiction" with bulimia nervosa (BN). Finally, little is understood about the association of "food addiction" with patterns of dieting and weight gain. The current study was conducted to address these gaps in the literature.

MATERIAL AND METHODS

Participants (N=815) were recruited from online advertisements nationwide and completed measures related to "food addiction", BMI, weight history, and disordered eating.

RESULTS

Addictive-like eating was associated with elevated current and lifetime highest BMI, weight cycling, and eating pathology. The prevalence of "food addiction" was higher in participants with BN than in those with binge eating disorder (BED). "Food addiction" continued to be related to clinically relevant variables, especially elevated BMI, even when participants did not meet criteria for BED or BN. The co-occurrence of "food addiction" with eating disorders appears to be associated with a more severe variant of eating pathology.

DISCUSSION

An addictive-type response to highly palatable food may be contributing to eating-related problems, including obesity and eating disorders. BN relative to BED appears to be more strongly associated with "food addiction." Additionally, the concept of "food addiction" appears to capture clinically relevant information in participants who do not meet criteria for either BN or BED. Further examination of "food addiction" may be important in understanding the mechanisms underlying certain types of problematic eating behavior.

The role of rs2237781 within GRM8 in eating behavior

INTRODUCTION

The glutamate receptor, metabotropic 8 gene (GRM8) encodes a G-protein-coupled glutamate receptor and has been associated with smoking behavior and liability to alcoholism implying a role in addiction vulnerability. Data from animal studies suggest that GRM8 may be involved in the regulation of the neuropeptide Y and melanocortin pathways and might influence food intake and metabolism. This study aimed to investigate the effects of the genetic variant rs2237781 within GRM8 on human eating behavior.

METHODS

The initial analysis included 548 Sorbs from Germany who have been extensively phenotyped for metabolic traits and who completed the German version of the three-factor eating questionnaire. In addition, we analyzed two independent sample sets comprising 293 subjects from another German cohort and 430 Old Order Amish individuals. Genetic associations with restraint, disinhibition, and hunger were assessed in an additive linear regression model.

RESULTS

Among the Sorbs the major G allele of rs2237781 was significantly associated with increased restraint scores in eating behavior (P = 1.9 × 10(-4); β = +1.936). The German cohort and the Old Order Amish population revealed a trend in the same direction for restraint (P = 0.242; β = +0.874; P = 0.908; β = +0.096; respectively). A meta-analysis resulted in a combined P = 3.1 × 10(-3) (Z-score 2.948).

CONCLUSION

Our data suggest that rs2237781 within GRM8 may influence human eating behavior factors probably via pathways involved in addictive behavior.

Effects of non-invasive neurostimulation on craving: a meta-analysis

This meta-analysis was conducted to evaluate the available evidence regarding the effects of non-invasive neurostimulation of the dorsolateral prefrontal cortex (DLPFC), on craving in substance dependence and craving for high palatable food. Non-invasive neurostimulation techniques were restricted to repetitive Transcranial Magnetic Stimulation (rTMS) and transcranial Direct Current Stimulation (tDCS). A total of 17 eligible studies were identified. Random effects analysis revealed a pooled standardized effect size (Hedge's g) of 0.476 (CI: 0.316-0.636), indicating a medium effect size favouring active non-invasive neurostimulation over sham stimulation in the reduction of craving (z=5.832, p<0.001). No significant differences were found between rTMS and tDCS, between the various substances of abuse and between substances of abuse and food, or between left and right DLPFC stimulation. In conclusion, this meta-analysis provides the first clear evidence that non-invasive neurostimulation of the DLPFC decreases craving levels in substance dependence.

Obesity and addiction: neurobiological overlaps

Drug addiction and obesity appear to share several properties. Both can be defined as disorders in which the saliency of a specific type of reward (food or drug) becomes exaggerated relative to, and at the expense of others rewards. Both drugs and food have powerful reinforcing effects, which are in part mediated by abrupt dopamine increases in the brain reward centres. The abrupt dopamine increases, in vulnerable individuals, can override the brain's homeostatic control mechanisms. These parallels have generated interest in understanding the shared vulnerabilities between addiction and obesity. Predictably, they also engendered a heated debate. Specifically, brain imaging studies are beginning to uncover common features between these two conditions and delineate some of the overlapping brain circuits whose dysfunctions may underlie the observed deficits. The combined results suggest that both obese and drug-addicted individuals suffer from impairments in dopaminergic pathways that regulate neuronal systems associated not only with reward sensitivity and incentive motivation, but also with conditioning, self-control, stress reactivity and interoceptive awareness. In parallel, studies are also delineating differences between them that centre on the key role that peripheral signals involved with homeostatic control exert on food intake. Here, we focus on the shared neurobiological substrates of obesity and addiction.