A literature review of dopamine in binge eating

An Efficient Combination Therapy with Lisdexamfetamine Dimesylate and Topiramate in Improving Binge Eating Scale & Metabolic Profile in Binge Eating Disorder: A Randomized Control Trial

Objective

Comprehensive evaluation of lisedexamfetamine dimesylate (LDX) alone and in combination with topiramate (TPM) was done for treatment of binge eating disorder (BED) in adults aged 18-55 years.

Methods

In the present randomized clinical trial study, 93 patients were selected by convenience sampling method and were allocated to two groups of 48 and 45 using the permuted block randomization method. This study was conducted from January to September 2022 in Shiraz, Iran. Patients received LDX (n = 48) or LDX plus TPM. Average dose of LDX was 37.5 mg/day and 38 mg/day in the first and second group respectively. The second group (n = 45) also received TPM with average dose of 77.7 mg/day.

Results

Twelve weeks treatment caused significant higher mean reduction in level of triglyceride (73.68 vs. 58.97 respectively, p = 0.024), low density lipo-protein (LDL) (9.66 vs. 5.16 respectively, p < 0.001) and body mass index (5.48 vs. 3.41 respectively, p < 0.001) with TPM plus LDX and also greater significant improvement (p < 0.001) in binge eating scale compared to use of LDX alone. Combination therapy with TPM and LDX had better tolerability and lower adverse events such as insomnia (p < 0.001), paresthesia (p = 0.001), confusion (p = 0.035) and ataxia (p = 0.009) compared to monotherapy in BED.

Conclusion

The combinative treatment was more effective than single drug in terms of higher tolerability, safety and causing lesser adverse events for BED patients. However, more studies with larger samples are needed.

Repeated binge-like eating episodes in female rats alter adenosine A2A and dopamine D2 receptor genes regulation in the brain reward system

OBJECTIVE

Binge-eating disorder is an eating disorder characterized by recurrent binge-eating episodes, during which individuals consume excessive amounts of highly palatable food (HPF) in a short time. This study investigates the intricate relationship between repeated binge-eating episode and the transcriptional regulation of two key genes, adenosine A2A receptor (A2AAR) and dopamine D2 receptor (D2R), in selected brain regions of rats.

METHOD

Binge-like eating behavior on HPF was induced through the combination of food restrictions and frustration stress (15 min exposure to HPF without access to it) in female rats, compared to control rats subjected to only restriction or only stress or none of these two conditions. After chronic binge-eating episodes, nucleic acids were extracted from different brain regions, and gene expression levels were assessed through real-time quantitative PCR. The methylation pattern on genes' promoters was investigated using pyrosequencing.

RESULTS

The analysis revealed A2AAR upregulation in the amygdala and in the ventral tegmental area (VTA), and D2R downregulation in the nucleus accumbens in binge-eating rats. Concurrently, site-specific DNA methylation alterations at gene promoters were identified in the VTA for A2AAR and in the amygdala and caudate putamen for D2R.

DISCUSSION

The alterations on A2AAR and D2R genes regulation highlight the significance of epigenetic mechanisms in the etiology of binge-eating behavior, and underscore the potential for targeted therapeutic interventions, to prevent the development of this maladaptive feeding behavior. These findings provide valuable insights for future research in the field of eating disorders.

PUBLIC SIGNIFICANCE

Using an animal model with face, construct, and predictive validity, in which cycles of food restriction and frustration stress evoke binge-eating behavior, we highlight the significance of epigenetic mechanisms on adenosine A2A receptor (A2AAR) and dopamine D2 receptor (D2R) genes regulation. They could represent new potential targets for the pharmacological management of eating disorders characterized by this maladaptive feeding behavior.

Exploring the Potential Impact of GLP-1 Receptor Agonists on Substance Use, Compulsive Behavior, and Libido: Insights from Social Media Using a Mixed-Methods Approach

Glucagon-like peptide-1 (GLP-1) is involved in a range of central and peripheral pathways related to appetitive behavior. Hence, this study explored the effects of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) on substance and behavioral addictions, including alcohol, caffeine, nicotine, cannabis, psychostimulants, compulsive shopping, and sex drive/libido. Data were collected from various social platforms. Keywords related to GLP-1 RAs and substance/behavioral addiction were used to extract relevant comments. The study employed a mixed-methods approach to analyze online discussions posted from December 2019 to June 2023 and collected using a specialized web application. Reddit entries were the focus here due to limited data from other platforms, such as TikTok and YouTube. A total of 5859 threads and related comments were extracted from six subreddits, which included threads about GLP-1 RAs drugs and associated brand names. To obtain relevant posts, keywords related to potential substance use and compulsive behavior were selected. Further analysis involved two main steps: (1) manually coding posts based on users' references to the potential impact of GLP-1 RAs on substance use and non-substance habits, excluding irrelevant or unclear comments; (2) performing a thematic analysis on the dataset of keywords, using AI-assisted techniques followed by the manual revision of the generated themes. Second, a thematic analysis was performed on the keyword-related dataset, using AI-assisted techniques followed by the manual revision of the generated themes. In total, 29.75% of alcohol-related; 22.22% of caffeine-related; and 23.08% of nicotine-related comments clearly stated a cessation of the intake of these substances following the start of GLP-1 RAs prescription. Conversely, mixed results were found for cannabis intake, and only limited, anecdotal data were made available for cocaine, entactogens, and dissociative drugs' misuse. Regarding behavioral addictions, 21.35% of comments reported a compulsive shopping interruption, whilst the sexual drive/libido elements reportedly increased in several users. The current mixed-methods approach appeared to be a useful tool in gaining insight into complex topics such as the effects of GLP-1 RAs on substance and non-substance addiction-related disorders; some GLP-1 RA-related mental health benefits could also be inferred from here. Overall, it appeared that GLP-1 RAs may show the potential to target both substance craving and maladaptive/addictive behaviors, although further empirical research is needed.

The Effectiveness of Transcranial Direct Current Stimulation (tDCS) in Binge Eating Disorder (BED)-Review and Insight into the Mechanisms of Action

INTRODUCTION

Binge eating disorder (BED) is the most common eating disorder among those contributing to the development of obesity, and thus acts as a significant burden on the lives and health of patients. It is characterized by complex neurobiology, which includes changes in brain activity and neurotransmitter secretion. Existing treatments are moderately effective, and so the search for new therapies that are effective and safe is ongoing.

AIM AND METHODS

This review examines the use of transcranial direct current stimulation (tDCS) in the treatment of binge eating disorder. Searches were conducted on the PubMed/Medline, Research Gate, and Cochrane databases.

RESULTS

Six studies were found that matched the review topic. All of them used the anodal stimulation of the right dorsolateral prefrontal cortex (DLPFC) in BED patients. tDCS proved effective in reducing food cravings, the desire to binge eat, the number of binging episodes, and food intake. It also improved the outcomes of inhibitory control and the treatment of eating disorder psychopathology. The potential mechanisms of action of tDCS in BED are explained, limitations in current research are outlined, and recommendations for future research are provided.

CONCLUSIONS

Preliminary evidence suggests that the anodal application of tDCS to the right DLPFC reduces the symptoms of BED. However, caution should be exercised in the broader use of tDCS in this context due to the small number of studies performed and the small number of patients included. Future studies should incorporate neuroimaging and neurophysiological measurements to elucidate the potential mechanisms of action of tDCS in BED.

Current perspectives on brain circuits involved in food addiction-like behaviors

There is an emerging view that the increased availability of energy-dense foods in our society is contributing to excessive food consumption which could lead to food addiction-like behavior. Particularly, compulsive eating patterns are predominant in people suffering from eating disorders (binge-eating disorder, bulimia and anorexia nervosa) and obesity. Phenotypically, the behavioral pattern exhibits a close resemblance to individuals suffering from other forms of addiction (drug, sex, gambling). Growing body of evidence in neuroscience research is showing that excessive consumption of energy-dense foods alters the brain circuits implicated in reward, decision-making, control, habit formation, and emotions that are central to drug addiction. Here, we review the current understanding of the circuits of food addiction-like behaviors and highlight the future possibility of exploring those circuits to combat obesity and eating disorders.

The role of habit in maintaining binge/purge behaviors: An ecological momentary assessment study

OBJECTIVE

Individuals with eating disorders transdiagnostically engage in binge eating (BE) and/or purging, despite life-threatening consequences. Little is known about factors that contribute to the persistence of these behaviors. This study explored whether habitual control over binge/purge (B/P) spectrum behaviors contributes to symptom persistence and whether negative reinforcement via reductions in negative affect is less influential in maintaining B/P behaviors that are under habitual control and are persistent.

METHOD

Women with BE and/or purging (N = 81) completed self-report measures assessing habit strength of BE and purging. Then, they completed a 14-day ecological momentary assessment (EMA) protocol during which they completed measures of negative affect, BE, and purging multiple times per day.

RESULTS

Habitual control over purging was associated with a greater frequency of purging during the EMA period. However, habitual control over BE was not associated with the severity of loss of control eating or the frequency of BE episodes. Habitual control did not moderate temporal relations between negative affect and B/P behaviors during the EMA period. However, exploratory analyses revealed that individuals with a longer duration of BE and greater habitual control over BE showed a less pronounced reduction in negative affect following BE.

DISCUSSION

Overall, these findings suggest that purging may be maintained by habitual stimulus-response learning. In addition, they support the possibility that reduction in negative affect may play a less prominent role in maintaining BE that is habitual and persistent.

PUBLIC SIGNIFICANCE

This study investigated whether habit contributes to the persistence of symptoms in women with binge/purge spectrum behaviors and whether negative reinforcement via reductions in negative affect is less influential in maintaining binge/purge behaviors that are under habitual control. The findings suggest that purging may be maintained through habit. This supports the potential utility of habit reversal interventions to decrease habitual purging.

Eating disorders and obesity: bridging clinical, neurobiological, and therapeutic perspectives

Eating disorders (EDs) and obesity are complex health conditions sharing various risk and maintenance factors, intensified in cases of comorbidity. This review explores the similarities and connections between these conditions, examining different facets from a multidisciplinary perspective, among them comorbidities, metabolic and psychological factors, neurobiological aspects, and management and therapy implications. We aim to investigate the common characteristics and complexities of weight and EDs and explore their interrelationships in individuals who experience both. The rising prevalence of EDs in people with obesity necessitates integrated approaches to study this comorbidity and to identify and analyze both common and distinct features of these conditions. This review may offer new opportunities for simultaneous prevention and management approaches, as well as future lines of research.

Exploring sub-threshold food addiction in adult patients with severe obesity: a cross-sectional analysis

BACKGROUND

Most studies on Food Addiction (FA) used the strict classical diagnosis approach without quantifying sub-threshold symptoms (i.e. uncontrolled/excessive food intake, negative affect, craving, tolerance, withdrawal, and continued use despite harm) nor indicating where they stand on the "three-stage addiction cycle" modeling the transition from substance use to addiction.

OBJECTIVES

(1) to estimate the proportion of clinically significant episodes of distress/impairment in severely obese patients without FA, and (2) to assess their associations with FA symptoms at the subthreshold level.

METHODS

The modified Yale Food Addiction Scale 2.0 (mYFAS 2.0) assesses 11 symptoms (diagnostic criteria) plus clinically significant impairment and distress (clinical significance criterion). We used this tool to diagnose FA (≥ 2 criteria plus clinical significance) in adult patients with severe obesity, but included only those below the threshold in the analyses. Demographics, clinical features, and obesity complications were collected.

RESULTS

Only 18% of the 192 participants (women n = 148, 77.1%; mean age: 43.0 ± 13.2) reported a total absence of FA symptoms, while one in four reported recurrent episodes of clinically significant distress (24%) or impairment (25%) in social, occupational, or other important areas of functioning. The most common recurrent symptoms were first-stage symptoms (binge/intoxication), while second- (withdrawal/negative affect) and third-stage (preoccupation/anticipation) symptoms affected nearly one patient in five for tolerance and craving, and one in ten for withdrawal. In multivariate analysis, impairment was positively related to withdrawal and tolerance, while distress was positively related to failure in role obligations.

CONCLUSION

Many patients with severe obesity experience recurrent episodes of FA symptoms at the subthreshold level. Prospective studies will examine whether these symptoms may play a causal role in symptoms progression toward a full-blown FA and obesity outcomes.

To Each His Own Fear: Gender-Related Association of Anxiety, Substance Use, and Eating Disorders in a Representative Birth Cohort Sample of Young Adults with Either COMT Val158Met allele

INTRODUCTION

The role of catechol-O-methyltransferase (COMT) in catecholamine neurotransmitter metabolism has led to the investigation of variants of the corresponding gene in the etiology of different psychiatric disorders, but the results are inconclusive.

METHODS

We have examined the relationship between COMT Val158Met single nucleotide polymorphism (rs4680) and the occurrence of psychiatric disorders in a highly representative birth cohort sample of young adults in the Estonian Children Personality Behaviour and Health Study (original n = 1,238). The lifetime occurrence of psychiatric disorders at the age of 25 years was assessed with the Mini-International Neuropsychiatric Interview.

RESULTS

Both Val- and Met-alleles of the COMT Val158Met were associated with specific psychiatric disorders. Met-allele carriers had a significantly higher occurrence of agoraphobia (3.2% vs. 0.5%; χ2 = 4.10; p < 0.05) compared to Val/Val homozygotes. Also, the occurrence of panic disorder was significantly higher in female Met-allele carriers than in Val/Val homozygote females (10.2% vs. 3.6%; χ2 = 4.62 p = 0.03). In contrast, the occurrence of generalized anxiety disorder was higher in Val/Val females when compared to Met-allele carriers (12.7% vs. 6.8%; χ2 = 4.16; p = 0.04). Also, female Val/Val homozygotes (15.5%) had a higher occurrence of eating disorders than Met-allele carriers (6.1%) of the COMT Val158Met polymorphism (χ2 = 10.39; p = 0.002). In the whole sample, Met-allele homozygotes had a higher occurrence of alcohol use and substance use disorders than Val-allele carriers (χ2 = 3.62 and 3.68, respectively; p < 0.05).

CONCLUSION

In a regional highly birth cohort representative sample, either COMT rs4680 variant was observed in association with specific psychiatric disorders.

Neuronal activity and reward processing in relation to binge eating

PURPOSE OF REVIEW

Studies increasingly show the importance of reward processing in binge eating and provide evidence of associated changes in the neurobiological reward system. This review gives an up-to-date overview of the neurobiological substrates of reward processing subconstructs in binge eating. Neural findings are linked to different behavioral theories and the clinical relevance is discussed.

RECENT FINDINGS

Increased neural responses in the orbitofrontal cortex, anterior cingulate cortex as well as striatum during anticipation and receipt of food rewards are found in association to binge eating. Increased model-free learning is also found and associated with altered brain reward reactivity. Data in rest report reduced striatal dopamine release and lower frontostriatal connectivity. Mechanisms of onset of binge eating are less clear, but specific personality traits, related to frontostriatal dysconnectivity, probably increase the risk of binge eating onset.

SUMMARY

Both structural and task-based imaging studies show differences in the neurobiological reward system in binge eating. These changes are linked to specific reward processing, such as altered reward responsiveness to food cues, reinforcement learning, and habitual behavior. Findings are lined with different behavioral theories of binge eating, and a staging model is described, from onset to full illness development. Understanding the specific underlying aberrant reward mechanism in binge eating, associated with different stages of the illness, enables caregivers to focus their treatment more precisely.

Dysfunctional decision-making in binge-eating disorder: A meta-analysis and systematic review

Binge-Eating Disorder (BED) involves anticipatory craving and urges, subjective loss-of-control during binge-eating episodes, and post-feeding psychological distress and guilt. Evidence indicates neurocognitive dysfunctions contribute to BED onset, maintenance, and treatment response. However, an integrated understanding of how cognitive processes underpin BED symptomology is lacking. We utilised a multi-stage decision-making model defining ten cognitive processes underpinning Preference Formation, Choice Implementation, Feedback Processing, and Flexibility/Shifting, to comprehensively review research published since 2013. We used preregistered PICOS criteria to assess 1966 articles identified from PubMed, PsycInfo, and Scopus database searches. This yielded 50 studies reporting behavioural cognitive tasks outcomes, comparing individuals with BED to controls with normal and higher weight. Meta-analyses revealed a unique profile of cognitive dysfunctions that spanned all decision-making stages. Significant deficits were evident in Uncertainty Evaluation, Attentional Inhibition, Choice Consistency, and Cognitive Flexibility/Set-shifting. We propose a novel model of dysfunctional decision-making processes in BED and describe their role in binge-eating behaviour. We further highlight the potential for cognitive interventions to target these processes and address the significant treatment gap in BED.

Potential biomarker of brain response to opioid antagonism in adolescents with eating disorders: a pilot study

Background

Eating Disorders (ED) affect up to 5% of youth and are associated with reward system alterations and compulsive behaviors. Naltrexone, an opioid antagonist, is used to treat ED behaviors such as binge eating and/or purging. The presumed mechanism of action is blockade of reward activation; however, not all patients respond, and the optimal dose is unknown. Developing a tool to detect objective drug response in the brain will facilitate drug development and therapeutic optimization. This pilot study evaluated neuroimaging as a pharmacodynamic biomarker of opioid antagonism in adolescents with ED.

Methods

Youth aged 13-21 with binge/purge ED completed functional magnetic resonance imaging (fMRI) pre- and post-oral naltrexone. fMRI detected blood oxygenation-level dependent (BOLD) signal at rest and during two reward probes (monetary incentive delay, MID, and passive food view, PFV) in predefined regions of interest associated with reward and inhibitory control. Effect sizes for Δ%BOLD (post-naltrexone vs. baseline) were estimated using linear mixed effects modeling.

Results

In 12 youth (16-21 years, 92% female), BOLD signal changes were detected following naltrexone in the nucleus accumbens during PFV (Δ%BOLD -0.08 ± 0.03; Cohen's d -1.06, p = 0.048) and anterior cingulate cortex during MID (Δ%BOLD 0.06 ± 0.03; Cohen's d 1.25, p = 0.086).

Conclusion

fMRI detected acute reward pathway modulation in this small sample of adolescents with binge/purge ED. If validated in future, larger trials, task-based Δ%BOLD detected by fMRI may serve as a pharmacodynamic biomarker of opioid antagonism to facilitate the development of novel therapeutics targeting the reward pathway, enable quantitative pharmacology trials, and inform drug dosing.

Clinical trial registration

https://clinicaltrials.gov/ct2/show/NCT04935931, NCT#04935931.

Current Discoveries and Future Implications of Eating Disorders

Eating disorders (EDs) are characterized by severe disturbances in eating behaviors and can sometimes be fatal. Eating disorders are also associated with distressing thoughts and emotions. They can be severe conditions affecting physical, psychological, and social functions. Preoccupation with food, body weight, and shape may also play an important role in the regulation of eating disorders. Common eating disorders have three major types: anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED). In some cases, EDs can have serious consequences for an individual's physical and mental health. These disorders often develop during adolescence or early adulthood and affect both males and females, although they are more commonly diagnosed in young adult females. Treatment for EDs typically involves a combination of therapy, nutrition counseling, and medical care. In this narrative review, the authors summarized what is known of EDs and discussed the future directions that may be worth exploring in this emerging area.

The Role of the Endocannabinoid System in Binge Eating Disorder

Eating disorders are multifactorial disorders that involve maladaptive feeding behaviors. Binge eating disorder (BED), the most prevalent of these in both men and women, is characterized by recurrent episodes of eating large amounts of food in a short period of time, with a subjective loss of control over eating behavior. BED modulates the brain reward circuit in humans and animal models, which involves the dynamic regulation of the dopamine circuitry. The endocannabinoid system plays a major role in the regulation of food intake, both centrally and in the periphery. Pharmacological approaches together with research using genetically modified animals have strongly highlighted a predominant role of the endocannabinoid system in feeding behaviors, with the specific modulation of addictive-like eating behaviors. The purpose of the present review is to summarize our current knowledge on the neurobiology of BED in humans and animal models and to highlight the specific role of the endocannabinoid system in the development and maintenance of BED. A proposed model for a better understanding of the underlying mechanisms involving the endocannabinoid system is discussed. Future research will be necessary to develop more specific treatment strategies to reduce BED symptoms.

Neuroendocrinological factors in binge eating disorder: A narrative review

Neuroendocrine mechanisms play a key role in the regulation of eating behavior. In individuals with binge eating disorder (BED), alterations in these mechanisms signaling hunger and satiety have been observed. It has been investigated that these alterations may underlie the development and maintenance of compulsive overeating in BED. The present narrative review examined the current literature related to the neurobiological processes involved in feeding dysregulation in BED with the aim of updating the most relevant aspects with special attention to neuroendocrine signaling. Studies have shown both central and peripheral endocrine dysfunctions in hormones participating in homeostatic and hedonic pathways in BED. Most studies have been especially focused on orexigenic signals, pointing out the existence of a hyperactivated mechanism promoting hunger. Fewer studies have explored anorexigenic pathways, but the findings so far seem to suggest an abnormal satiety threshold. Despite this, to date, it is unable to identify whether these alterations are typical of the BED pathophysiology or are related to an obesogenic pattern due to most studies included patients with BED and obesity. The identification of endophenotypes in BED may provide a new approach to aberrant eating behavior, favoring the implementation of biological therapeutic targets.

Genetic and epigenetic effects on couple adjustment in context of romantic relationship: A scoping systematic review

Introduction: Couples' relationships defined by a complex interaction between the two partners and their intrapersonal traits. Romantic; relationships and love are associated with marital satisfaction and stability, as well as couples' happiness and health. Personality traits influence romantic relationships and, personality influenced by genetical and non-genetically factors. The roles of non-genetically factors such as socioeconomic position and external appearance have revealed in determining the quality of romantic relationships. Methods: We; performed a scoping systematic review to assess the association between genetics and epigenetic factors and romantic relationship. Relevant articles were identified by PubMed, EMBASE, Web of Science, Scopus, and the APA PsycInfo searching between inception and 4 June 2022. Results: Different studies evaluated the associated polymorphisms in 15 different genes or chromosomal regions. In the first step; we classified them into four groups: (1) Oxytocin-related signaling pathway (OXTR, CD38, and AVPR1A); (2) Serotonin-related signaling pathway (SLC6A4, HTR1A, and HTR2A); (3) Dopamine and catecholamine-related signaling pathway (DRD1, DRD2, DRD4, ANKK1, and COMT); and (4) other genes (HLA, GABRA2, OPRM1, and Y-DNA haplogroup D-M55). Then, we evaluated and extracted significant polymorphisms that affect couple adjustment and romantic relationships. Discussion: Overall, the findings suggest that genetic and epigenetics variants play a key role in marital adjustment and romantic relationships over time.