The genetics of eating disorders

Association of serotonin receptor gene polymorphisms with anorexia nervosa: a systematic review and meta-analysis

PURPOSE

Several studies have investigated the association between anorexia nervosa and polymorphisms of genes regulating serotonin neurotransmission, with a focus on the rs6311 polymorphism of 5-HTR2A. However, inconsistent results of these studies and conflicting conclusions of existing meta-analyses complicate the understanding of a possible association. We have updated these results and evaluated the involvement of other serotonin receptor gene polymorphisms in anorexia nervosa.

METHODS

Adhering to PRISMA guidelines, we have searched studies on anorexia nervosa and serotonin-regulating genes published from 1997 to 2022, selected those concerning receptor genes and meta-analyzed the results from twenty candidate gene studies on the 5-HTR2A rs6311 polymorphism and the 5-HTR2C rs6318 polymorphism.

RESULTS

Present analyses reveal an association for the 5-HTR2A rs6311 polymorphism, with G and A alleles, across eighteen studies (2049 patients, 2877 controls; A vs. G allele, Odds Ratio = 1.24; 95% Confidence Interval = 1.06-1.47; p = 0.009). However, after geographic subgrouping, an association emerged only in a Southern European area, involving five studies (722 patients, 773 controls; A vs. G allele, Odds Ratio = 1.82; 95% Confidence Interval = 1.41-2.37; p < 0.00001). No association was observed for the 5-HTR2C rs6318 polymorphism across three studies.

CONCLUSIONS

To date, the involvement in the pathophysiology of anorexia nervosa of the 5-HTR2A rs6311 polymorphism appears limited to a specific genetic and/or environmental context, while that of the 5-HTR2C rs6318 polymorphism seems excluded. Genome-wide association studies and epigenetic studies will likely offer deeper insights of genetic and environmental factors possibly contributing to the disorder.

LEVEL OF EVIDENCE

III Evidence obtained from well-designed cohort or case-control analytic studies. Clinical trial registration PROSPERO registration number: CRD42021246122.

Shared genetic influences between eating disorders and gastrointestinal disease in a large, population-based sample of adult women and men

BACKGROUND

Some preliminary research suggests higher rates of gastrointestinal disease in individuals with eating disorders (EDs). However, research is limited, and it remains unknown what etiologic factors account for observed associations. This was the first study to examine how EDs and dimensional ED symptoms (e.g. body dissatisfaction, binge eating) are phenotypically and etiologically associated with gastrointestinal disease in a large, population-based twin sample.

METHODS

Adult female (N = 2980) and male (N = 2903) twins from the Michigan State University Twin Registry reported whether they had a lifetime ED (anorexia nervosa, bulimia nervosa, or binge-eating disorder) and completed a measure of dimensional ED symptoms. We coded the presence/absence of lifetime gastrointestinal disease (e.g. inflammatory bowel disease) based on responses to questions regarding chronic illnesses and medications. We first examined whether twins with gastrointestinal disease had higher rates of EDs and ED symptoms, then used correlated factors twin models to investigate genetic and environmental contributions to the overlap between disorders.

RESULTS

Twins with gastrointestinal disease had significantly greater dimensional ED symptoms (β = 0.21, p < 0.001) and odds of a lifetime ED (OR 2.90, p = 0.001), regardless of sex. Shared genetic factors fully accounted for the overlap between disorders, with no significant sex differences in etiologic associations.

CONCLUSIONS

Comorbidity between EDs and gastrointestinal disease may be explained by overlap in genetic influences, potentially including inflammatory genes implicated in both types of disorders. Screening for gastrointestinal disease in people with EDs, and EDs in those with gastrointestinal disease, is warranted.

Temperament impact on eating disorder symptoms and habit formation: a novel model to inform treatment

BACKGROUND

Temperament has long been described as the biological dimension of personality. Due to advancing brain-imaging technology, our understanding of temperament has deepened and transformed over the last 25 years. Temperament combines genetic, neurobiological and trait research. Temperament has been included peripherally in some eating disorder (ED) treatment approaches but has been ignored by most. Temperament fills a fundamental treatment gap by clarifying who is more vulnerable to develop ED and why some individuals are susceptible to specific ED symptoms while others are not. In addition, temperament targets possible treatment solutions.

MAIN TEXT

There is a need for a novel model that incorporates and explores the role of temperament in ED treatment intervention. This paper is a metaphoric temperament model to inform treatment intervention. It describes how temperament traits influences new decisions which impact new behavioural responses. In turn, it neurobiologically tracks how and why the brain efficiently transforms new decisions into new habits. This model integrates both temperament and habit research to explore (a) what temperament is; (b) how new decisions develop into habits neurobiologically; (c) that the brain wires destructive symptoms into habits in the same way that it wires healthy/productive behaviours into habits; (d) traits that trigger ED symptoms are the same traits that influence productive behaviours; and in regard to treatment implications (e) when treatment structure and intervention target client temperaments, the potential for new healthy "trait-syntonic" habits could develop.

CONCLUSIONS

This paper introduces a metaphoric model that synthesizes and integrates temperament neurobiological and trait findings with ED symptoms, habits, and client trait-based solutions. The model synthesizes and integrates different research domains to establish a brain-based foundation to inform treatment intervention. The model targets clients' temperament traits as central collections of innate self-expressions that could be utilized as tools to redirect client trait-syntonic ED responses into trait-syntonic productive outcomes. The brain bases of temperament and habit formation serve as a biological foundation for ED treatment intervention.

Exposures during pregnancy and at birth are associated with the risk of offspring eating disorders

BACKGROUND

Eating disorders (ED) are severe psychiatric disorders, commonly debuting early. Aberrances in the intrauterine environment and at birth have been associated with risk of ED. Here, we explore if, and at what effect size, a variety of such exposures associate with offspring ED, that is, anorexia nervosa (AN), bulimia nervosa (BN), and eating disorder not otherwise specified (EDNOS).

METHODS

This population-based cohort study, conducted from September 2021 to August 2023, used Finnish national registries of all live births in 1996-2014 (N = 1,097,753). Cox proportional hazards modeling was used to compare ED risk in exposed versus unexposed offspring, adjusting for potential confounders and performing sex-stratified analyses.

RESULTS

A total of 6614 offspring were diagnosed with an ED; 3668 AN, 666 BN, and 4248 EDNOS. Lower risk of offspring AN was seen with young mothers, continued smoking, and instrumental delivery, while higher risk was seen with older mothers, inflammatory disorders, prematurity, small for gestational age, and low Apgar. Offspring risk of BN was higher with continued smoking and prematurity, while lower with postmature birth. Offspring risk of EDNOS was lower with instrumental delivery, higher for older mothers, polycystic ovary syndrome, insulin-treated pregestational diabetes, antibacterial treatment, prematurity, and small for gestational age. Sex-specific associations were found.

CONCLUSIONS

Several prenatal and at birth exposures are associated with offspring ED; however, we cannot exclude confounding by maternal BMI. Nevertheless, several exposures selectively associate with risk of either AN, BN, or EDNOS, and some are sex-specific, emphasizing the importance of subtype- and sex-stratified analyses of ED.

PUBLIC SIGNIFICANCE

We define environmental factors involved in the development of different ED, of importance as preventive measure, but also in order to aid in defining the molecular pathways involved and thus in the longer perspective contribute to the development of pharmacological treatment of ED.

Family-based treatment takes longer for adolescents with mental health comorbidities: findings from a community mental health service

Children and adolescents diagnosed with an eating disorder often meet the diagnosis of another mental health disorder. In addition to eating disorders, individuals with comorbid disorders have higher suicide rates and more severe and chronic eating disorder symptoms. The present research aimed to investigate the influence of comorbid conditions on the treatment outcomes of children and adolescents that attended a public community mental health service. It was hypothesised that the patients with comorbidities would have a more extended treatment duration, slower rates of weight restoration, more hospital admissions for medical compromise, and poorer functioning than those without comorbidities. Data from 78 past patients at the Eating Disorder Program in Queensland, Australia, were analysed. Patients with comorbidities demonstrated similar recovery rates to those without comorbidities. However, those with comorbid conditions had longer episodes of treatment. The study's results support using Family Based Treatment for patients with and without comorbidities. The implications of the findings for public mental health services and directions for future research are discussed.

The gut microbiota contributes to the pathogenesis of anorexia nervosa in humans and mice

Anorexia nervosa (AN) is an eating disorder with a high mortality. About 95% of cases are women and it has a population prevalence of about 1%, but evidence-based treatment is lacking. The pathogenesis of AN probably involves genetics and various environmental factors, and an altered gut microbiota has been observed in individuals with AN using amplicon sequencing and relatively small cohorts. Here we investigated whether a disrupted gut microbiota contributes to AN pathogenesis. Shotgun metagenomics and metabolomics were performed on faecal and serum samples, respectively, from a cohort of 77 females with AN and 70 healthy females. Multiple bacterial taxa (for example, Clostridium species) were altered in AN and correlated with estimates of eating behaviour and mental health. The gut virome was also altered in AN including a reduction in viral-bacterial interactions. Bacterial functional modules associated with the degradation of neurotransmitters were enriched in AN and various structural variants in bacteria were linked to metabolic features of AN. Serum metabolomics revealed an increase in metabolites associated with reduced food intake (for example, indole-3-propionic acid). Causal inference analyses implied that serum bacterial metabolites are potentially mediating the impact of an altered gut microbiota on AN behaviour. Further, we performed faecal microbiota transplantation from AN cases to germ-free mice under energy-restricted feeding to mirror AN eating behaviour. We found that the reduced weight gain and induced hypothalamic and adipose tissue gene expression were related to aberrant energy metabolism and eating behaviour. Our 'omics' and mechanistic studies imply that a disruptive gut microbiome may contribute to AN pathogenesis.

Anorexia Nervosa in Juvenile Systemic Lupus Erythematosus (SLE): A Causality Dilemma

Juvenile-onset systemic lupus erythematosus (jSLE) is an autoimmune disorder with multifaceted clinical findings in different organ systems. Neuropsychiatric manifestations affect more than half of SLE patients, and there is increasing evidence that anorexia nervosa (AN), a feeding and eating disorder (FED) characterized by significantly reduced energy intake, is among them. Herein, a review of the literature on the potential association between jSLE and AN was performed. Reported clinical cases were identified, and putative pathophysiological mechanisms were sought that could potentially explain the observed relationship between these two pathological entities. Four reports of isolated cases and a case series including seven patients were identified. In this limited patient pool, the diagnosis of AN preceded that of SLE in the majority of cases, whereas in all cases both entities were diagnosed within a time span of two years. Many explanations for the observed relationships have been proposed. AN has been associated with the stress of chronic disease diagnosis; on the other hand, the chronic inflammation associated with AN may contribute to the development/appearance of SLE. Adverse childhood experiences, concentrations of leptin, shared autoantibodies, and genetic traits appear to be important factors in this well-established interplay. In essence, it seems important to increase clinician awareness of the concomitant development of AN and SLE and invite further research on the subject.

The role of the brain-derived neurotrophic factor (BDNF) in anorexia nervosa

The brain-derived neurotrophic factor (BDNF) is a growth factor belonging to the neurotrophin family which plays a pivotal role in the differentiation, survival, and plasticity of neurons in the central nervous system. Evidence suggests that BDNF is an important signal molecule in the regulation of energy balance and thus implicated in body weight control. The discovery of BDNF-expressing neurons in the paraventricular hypothalamus which is important in the regulation of energy intake, physical activity, and thermogenesis gives more evidence to the suggested participation of BDNF in eating behavior. Until now it remains questionable whether BDNF can be used as a reliable biomarker for eating disorders such as anorexia nervosa (AN) as available findings on BDNF levels in patients with AN are ambiguous. AN is an eating disorder characterized by a pathological low body weight in combination with a body image disturbance typically developing during adolescence. A severe drive for thinness leads to restrictive eating behavior often accompanied by physical hyperactivity. During therapeutic weight restoration an increase of BDNF expression levels seems desirable as it might improve neuronal plasticity and survival which is essential for learning processes and thereby essential for the success of the psychotherapeutic treatment of patients. On the contrary, the well-known anorexigenic effect of BDNF might favor relapse in patients as soon as the BDNF levels significantly increase during weight rehabilitation. The present review summarizes the association between BDNF and general eating behavior and especially focuses on the eating disorder AN. In this regard findings from preclinical AN studies (activity-based anorexia model) are outlined as well.

Preventing eating disorders and disordered eating in genetically vulnerable, high-risk families

OBJECTIVE

To close the chasm between theory about families containing a parent with an eating disorders (EDs) history and lack of selective or indicated prevention programming for such families with an older child or adolescent who is, genetically, at high risk.

METHOD

A search of four major databases for January 2000 through September 2022 yielded no publications that (a) identified genetically high-risk families with offspring ages 10 through 18; (b) devised a prevention program for the family; and (c) evaluated program effects on risk/protective factors. To rectify this gap, research on three lines of family-based prevention is reviewed: (1) programs for adolescents at genetic risk for depression or anxiety; (2) the Stanford-Dresden project for adolescents at high risk for anorexia nervosa; and (3) Sadeh-Sharvit et al.'s work concerning the Parent-Based Prevention program for mothers with an EDs history and a child under age 5.

RESULTS

The significant challenges for innovative prevention programming should be addressed by experts in effective EDs, depression, and anxiety prevention, and in family-based treatment (FBT) for EDs, collaborating with people from genetically vulnerable families. Innovative programming should focus on robust risk factors for EDs, adaptive expression of non-specific risk factors (e.g., temperament), and strengthening family functioning.

DISCUSSION

The field is overdue for development of prevention programs designed for older children or adolescents who are at risk because a parent has an ED. Evidence-based prevention programs for EDs and for depression and anxiety, as well as parent-based prevention informed by FBT, provide a springboard for addressing this gap.

PUBLIC SIGNIFICANCE

The foundation of theory and research is available for stakeholders to develop prevention programming that closes the huge gap between theory and research about families that are genetically vulnerable for eating disorders versus the complete lack of prevention programming for such families that have an older child or adolescent at high risk.

SLC6A4 DNA Methylation Levels and Serum Kynurenine/Tryptophan Ratio in Eating Disorders: A Possible Link with Psychopathological Traits?

Background: The incidence of eating disorders (EDs), serious mental and physical conditions characterized by a disturbance in eating or eating-related behaviors, has increased steadily. The present study aims to develop insights into the pathophysiology of EDs, spanning over biochemical, epigenetic, psychopathological, and clinical data. In particular, we focused our attention on the relationship between (i) DNA methylation profiles at promoter-associated CpG sites of the SCL6A4 gene, (ii) serum kynurenine/tryptophan levels and ratio (Kyn/Trp), and (iii) psychopathological traits in a cohort of ED patients. Among these, 45 patients were affected by restricting anorexia nervosa (AN0), 21 by purging AN (AN1), 21 by bulimia (BN), 31 by binge eating disorders (BED), 23 by unspecified feeding or eating disorders (UFED), and finally 14 by other specified eating disorders (OSFED) were compared to 34 healthy controls (CTRs). Results: Kyn level was higher in BED, UFED, and OSFED compared to CTRs (p ≤ 0.001). On the other hand, AN0, AN1, and BN patients showed significatively lower Kyn levels compared to the other three ED groups but were closed to CTRs. Trp was significantly higher in AN0, AN1, and BN in comparison to other ED groups. Moreover, AN1 and BN showed more relevant Trp levels than CTRs (p <0.001). BED patients showed a lower Trp as compared with CTRs (p ≤ 0.001). In addition, Kyn/Trp ratio was lower in the AN1 subtype but higher in BED, UFED, and OSFED patients than in CTRs (p ≤ 0.001). SCL6A4 DNA methylation level at CpG5 was lower in AN0 compared to BED (p = 0.021), and the CpG6 methylation was also significantly lower in AN0 in comparison to CTRs (p = 0.025). The mean methylation levels of the six CpGs analyzed were lower only in the AN0 subgroup compared to CTRs (p = 0.008). Relevant psychological trait EDI-3 subscales were correlated with biochemical and epigenetic data. Conclusions: These findings underline the complexity of psychological and pathophysiological components of EDs.

Gene variants in eating disorders. Focus on anorexia nervosa, bulimia nervosa, and binge-eating disorder

Eating disorders such as anorexia nervosa, bulimia nervosa and binge-eating disorder, have a deep social impact, concluding with death in cases of severe disease. Eating disorders affect up to 5% of the population in the industrialized countries, but probably the phenomenon is under-detection and under-diagnosis. Eating disorders are multifactorial disorders, resulting from the interaction between environmental triggers, psychological factors, but there is also a strong genetic component. In fact, genetic factors predispose for approximately 33-84% to anorexia nervosa, 28-83% to bulimia nervosa, and 41-57% to binge eating disorder. Twins and family studies have provided an unassailable proof on the heritability of these disorders. Other types of genetic studies, including genome-wide association studies, whole genome sequencing and linkage analysis, allowed to identify the genes and their variants associated with eating disorders and moreover global collaborative efforts have led to delineate the etiology of these disorders. Next Generation Sequencing technologies can be considered as an ideal diagnostic approach to identify not only the common variants, such as single nucleotide polymorphism, but also rare variants. Here we summarize the present knowledge on the molecular etiology and genetic determinants of eating disorders including serotonergic genes, dopaminergic genes, opioid genes, appetite regulation genes, endocannabinoid genes and vitamin D3.

Sex as a Biological Variable in Nutrition Research: From Human Studies to Animal Models

Biological sex is a fundamental source of phenotypic variability across species. Males and females have different nutritional needs and exhibit differences in nutrient digestion and utilization, leading to different health outcomes throughout life. With personalized nutrition gaining popularity in scientific research and clinical practice, it is important to understand the fundamentals of sex differences in nutrition research. Here, we review key studies that investigate sex dimorphism in nutrition research: sex differences in nutrient intake and metabolism, sex-dimorphic response in nutrient-restricted conditions, and sex differences in diet and gut microbiome interactions. Within each area above, factors from sex chromosomes, sex hormones, and sex-specific loci are highlighted.

Obsessed with Healthy Eating: A Systematic Review of Observational Studies Assessing Orthorexia Nervosa in Patients with Diabetes Mellitus

Orthorexia nervosa (ON) is an unspecified feeding or eating disorder (USFED) characterized by an exaggerated, unhealthy obsession with healthy eating. Τypical eating disorders (EDs) and USFEDs are common among patients with diabetes mellitus (DM), which complicates metabolic control and disease outcomes. The present systematic review summarizes the evidence on the prevalence of ON symptomatology among patients with DM. PubMed, Web of Science, Scopus, and grey literature were searched, and relevant observational studies were screened using the Rayyan software. The quality of the studies was assessed using the appraisal tool for cross-sectional studies (AXIS) and the Newcastle–Ottawa scale (NOS). Out of 4642 studies, 6 fulfilled the predefined criteria and were included in the qualitative synthesis. Most studies relied on the ORTO-15 or its adaptations to identify ON among patients with DM. No apparent sex or age differences exist regarding the prevalence of ON symptoms. None of the studies compared the prevalence of ON in patients with type 1 and type 2 DM. Most of the research was of average to good methodological quality. In conclusion, patients with DM often exhibit ON tendencies, although research is still limited regarding the etiology or mechanistic drivers behind ON and the characteristics of patients with a dual ON–DM diagnosis.

The Central Role of Hypothermia and Hyperactivity in Anorexia Nervosa: A Hypothesis

Typically, the development of anorexia nervosa (AN) is attributed to psycho-social causes. Several researchers have recently challenged this view and suggested that hypothermia and hyperactivity (HyAc) are central to AN. The following hypothesis will attempt to clarify their role in AN. Anorexia nervosa patients (ANs) have significantly lower core temperatures (T_core) compared to healthy controls (HCs). This reduced temperature represents a reset T_core that needs to be maintained. However, ANs cannot maintain this T_core due primarily to a reduced basal metabolic rate (BMR); BMR usually supplies heat to sustain T_core. Therefore, to generate the requisite heat, ANs revert to the behavioral-thermoregulatory strategy of HyAc. The majority of ANs (~89%) are reportedly HyAc. Surprisingly, engagement in HyAc is not motivated by a conscious awareness of low T_core, but rather by the innocuous sensation of "cold- hands" frequently reported by ANs. That is, local hand-thermoreceptors signal the brain to initiate HyAc, which boosts perfusion of the hands and alters the sensation of "cold-discomfort" to one of "comfort." This "rewarding" consequence encourages repetition/habit formation. Simultaneously, hyperactivity increases the availability of heat to assist with the preservation of T_core. Additionally, HyAc induces the synthesis of specific brain neuromodulators that suppress food intake and further promote HyAc; this outcome helps preserve low weight and perpetuates this vicious cycle. Based on this hypothesis and supported by rodent research, external heat availability should reduce the compulsion to be HyAc to thermoregulate. A reduction in HyAc should decrease the production of brain neuromodulators that suppress appetite. If verified, hopefully, this hypothesis will assist with the development of novel treatments to aid in the resolution of this intractable condition.

The impact of COMT, BDNF and 5-HTT brain-genes on the development of anorexia nervosa: a systematic review

PURPOSE

The genetic aspect of anorexia nervosa (AN) involving specific genes of the central-nervous-system has not yet been clearly understood. The aim of this systematic review is to assess the impact of three candidate genes of the brain: catechol-O-methyltransferase, brain-derived neurotrophic factor (BDNF) and serotonin transporter protein, on the susceptibility to AN and identify whether a clear connection persists between each of the gene-polymorphisms and AN.

METHODS

A total of 21 articles were selected for this review conforming to the PRISMA guidelines. Detailed keyword combinations were implemented within specific databases such as MEDLINE, SCIENCEDIRECT and PUBMED.

RESULTS

The catechol-O-methyltransferase gene-polymorphism did not show any change in phenotypic variation between AN and control subjects; but the familial association was rather strong with an over-transmission of the H allele. The latter also correlated with several dimensions of the Temperament and Character Inventory (TCI) scale. A notable relation was indicated between BDNF gene-polymorphism and anorexia-restrictive in terms of phenotypic distribution; the Met66-allele also depicted high association with anorexic behavioral traits. The 5-HTTLPR gene-polymorphism was found to be significantly associated with AN susceptibility with an over-transmission of the S-allele from parents to offspring.

CONCLUSION

The systematic review distinctively emphasized the genetic contribution of the brain-genes on the development of AN. Despite significant study findings, no clear and standardized genetic route was determined to be the cause of AN development. Future research is needed on these specific genes to closely monitor the genetic polymorphisms and their mechanism on AN susceptibility.

LEVEL OF EVIDENCE

I, systematic review.

Association of 5-HTR2A -1438A/G polymorphism with anorexia nervosa and bulimia nervosa: A meta-analysis

Although a number of studies have been conducted on the association of -1438A/G polymorphism in serotonin 2A receptor (5-HTR2A) gene with anorexia nervosa (AN) and bulimia nervosa (BN), the results remained inconsistent. We thus performed a meta-analysis to clarify the effects of -1438A/G polymorphism on the risk of AN and BN. PubMed, Embase, the Cochrane Library, CNKI, Weipu and Wanfang databases were searched for eligible studies. Pooled odds ratio (OR) and 95 % confidence interval (CI) were calculated to estimate the strength of the association. Subgroup analysis was also performed by ethnicity. In total, 17 studies were included for the meta-analysis, of which 15 studies containing 2028 cases and 2725 controls were used for AN analysis and 7 studies containing 505 cases and 1129 controls for BN analysis. The results showed -1438A/G polymorphism was significantly associated with the risk of AN in four genetic models (allele model, A vs. G: OR = 1.31, 95 % CI = 1.11-1.64, P = 0.003; recessive model, AA vs. GA + GG: OR = 1.69, 95 % CI = 1.28-2.23, P = 0.000; dominant model, AA + GA vs. GG: OR = 1.35, 95 % CI = 1.02-1.79, P = 0.037; co-dominant model, AA vs. GG: OR = 1.94, 95 % CI = 1.29-2.92, P = 0.002) in Caucasians, but not in Asians. We failed to observe a significant association between -1438A/G polymorphism and the risk of BN either in overall or in Caucasian population. The present meta-analysis indicated that A allele and AA genotype of 5-HTR2A -1438A/G polymorphism may contribute to higher risk of AN, especially in Caucasians. However, this polymorphism was not associated with the susceptibility to BN.

The role of prenatal and perinatal factors in eating disorders: a systematic review

Numerous studies showed that factors influencing fetal development and neonatal period could lead to lasting alterations in the brain of the offspring, in turn increasing the risk for eating disorders (EDs). This work aims to systematically and critically review the literature on the association of prenatal and perinatal factors with the onset of EDs in the offspring, updating previous findings and focusing on anorexia nervosa (AN) and bulimia nervosa (BN). A systematic literature search was performed on Pubmed, PsycINFO, and Scopus. The drafting of this systematic review was conducted following the PRISMA statement criteria and the methodological quality of each study was assessed by the MMAT 2018. A total of 37 studies were included in this review. The factors that showed a more robust association with AN were higher maternal age, preeclampsia and eclampsia, multiparity, hypoxic complications, prematurity, or being born preterm (< 32 weeks) and small for gestational age or lower birth size. BN was only associated with maternal stress during pregnancy. Many methodological flaws emerged in the considered studies, so further research is needed to clarify these inconsistencies. Altogether, data are suggestive of an association between prenatal and perinatal factors and the onset of EDs in the offspring. Nevertheless, given the methodological quality of the available literature, firm conclusions cannot be drawn and whether this vulnerability is specific to EDs or mental disorders remains to be defined. Also, a strong need for longitudinal and well-designed studies on this topic emerged.

Dissection of the Genetic Association between Anorexia Nervosa and Obsessive-Compulsive Disorder at the Network and Cellular Levels

Anorexia nervosa (AN) and obsessive-compulsive disorder (OCD) exhibit a high co-morbidity rate, similar symptoms, and a shared genetic basis. However, an understanding of the specific underlying mechanisms of these commonalities is currently limited. Here, we collected Genome-Wide Association Analysis results for AN and OCD, and obtained genes hit by the top SNPs as the risk genes. We then carried out an integrative coexpression network analysis to explore the convergence and divergence of AN and OCD risk genes. At first, we observed that the AN risk genes were enriched in coexpression modules that involved extracellular matrix functions and highly are expressed in the postnatal brain, limbic system, and non-neuronal cell types, while the OCD risk genes were enriched in modules of synapse function, the prenatal brain, cortex layers, and neurons. Next, by comparing the expressions from the eating disorder and OCD postmortem patient brain tissues, we observed both disorders have similar prefrontal cortex expression alterations influencing the synapse transmission, suggesting that the two diseases could have similar functional pathways. We found that the AN and OCD risk genes had distinct functional and spatiotemporal enrichment patterns but carried similar expression alterations as a disease mechanism, which may be one of the key reasons they had similar but not identical clinical phenotypes.

No association between dopaminergic polymorphisms and response to treatment of binge-eating disorder

BACKGROUND

The genetics of binge-eating disorder (BED) is an emerging topic, with dopaminergic genes being implicated in its etiology due to the role that dopamine (DA) plays in food reward sensitivity and self-regulation of eating behavior. However, no study to date has examined if DA genes influence response to behavioral treatment of BED.

OBJECTIVE

The primary objective of this study was to examine the ability of DA-associated polymorphisms to predict BED treatment response measured using binge frequency over 12 months. As secondary objectives, this study examined cross-sectional relationships between these polymorphisms and anthropometrics in women living with and without BED and obesity.

METHODS

Women aged 18-64 years old were genotyped for the DA-related SNPs DRD2/ANKK1 Taq1A (rs1800497) and COMT (rs4680), as well as the DA-related uVNTRs DAT-1 (SLC6A3) and MAO-A. A multi-locus DA composite score was formed from these 4 polymorphisms using genotypes known to have a functional impact resulting in modified DA signaling. Binge frequency (Eating Disorder Examination - Interview) and body composition (Tanita BC-418) were assessed in a pre-post analysis to examine genetic predictors of treatment response in women living with obesity and BED. Secondary data analysis was conducted on a cross-sectional comparison of three groups of women enrolled in trial group treatment for BED: women living with obesity and BED (n = 72), obesity without BED (n = 27), and normal-weight without BED (n = 45).

RESULTS

There were no significant genotype × time interactions related to anthropometrics or binge frequency for any individual DA genotypes, or to the composite score reflecting DA availability. At baseline, there were no significant between-group differences in frequencies of DA-related alleles, nor were there associations between genotypes and anthropometrics.

CONCLUSIONS

Our study found no evidence to suggest that the DRD2/ANKK1 Taq1A, COMT, MAO-A, or DAT-1 polymorphisms are associated with response to behavioral intervention for BED as measured by changes in binge frequency. Future studies should examine a greater variety of dopaminergic polymorphisms, other candidate genes that target other neurotransmitter systems, as well as examine their impact on both behavioral and pharmacological-based treatment for BED.

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.

The Neurobiology of Binge-eating Disorder Compared with Obesity: Implications for Differential Therapeutics

PURPOSE

Emerging work indicates divergence in the neurobiologies of binge-eating disorder (BED) and obesity despite their frequent co-occurrence. This review highlights specific distinguishing aspects of BED, including elevated impulsivity and compulsivity possibly involving the mesocorticolimbic dopamine system, and discusses implications for differential therapeutics for BED.

METHODS

This narrative review describes epidemiologic, clinical, genetic, and preclinical differences between BED and obesity. Subsequently, this review discusses human neuroimaging work reporting differences in executive functioning, reward processing, and emotion reactivity in BED compared with obesity. Finally, on the basis of the neurobiology of BED, this review identifies existing and new therapeutic agents that may be most promising given their specific targets based on putative mechanisms of action relevant specifically to BED.

FINDINGS

BED is characterized by elevated impulsivity and compulsivity compared with obesity, which is reflected in divergent neurobiological characteristics and effective pharmacotherapies. Therapeutic agents that influence both reward and executive function systems may be especially effective for BED.

IMPLICATIONS

Greater attention to impulsivity/compulsivity-related, reward-related, and emotion reactivity-related processes may enhance conceptualization and treatment approaches for patients with BED. Consideration of these distinguishing characteristics and processes could have implications for more targeted pharmacologic treatment research and interventions.

Assessing for Eating Disorders: A Primer for Gastroenterologists

Eating disorders involve irregularities in eating behavior that may cause gastrointestinal (GI) symptoms. Consequently, many patients with eating disorders seek gastroenterological healthcare at some point in their illness, with many seeking this care even before they seek treatment for and/or diagnosed with their eating disorder. As such, the gastroenterology provider is in a unique position to identify, manage, and facilitate treatment for an eating disorder early in the course of the illness. Although assessing eating disorders is already a difficult task, the identification of eating disorders in patients with GI disease represents an even greater challenge. In particular, common GI symptoms, such as nausea, vomiting, and bloating, may disguise an eating disorder because these symptoms are often viewed as a sufficient impetus for dietary restriction and subsequent weight loss. In addition, the focus on identifying an organic etiology for the GI symptoms can distract providers from considering an eating disorder. During this prolonged diagnostic evaluation, the eating disorder can progress in severity and become more difficult to treat. Unfortunately, a misconception that hinders eating disorder detection is the notion that the rate or method of weight loss is associated with an eating disorder. Regardless of whether weight loss is slow or rapid, purposeful or accidental, eating disorder behaviors and thought patterns may be present. Unidentified eating disorders are not only dangerous in their own right but also can interfere with effective management of GI disease and its symptoms. As such, it is imperative for the GI provider to remain well versed in the identification of these diseases.

The impact of active or passive food preparation versus distraction on eating behaviour: An experimental study

Research indicates a role for attention in the perception of hunger and food intake. The present experimental study aimed to explore the impact of attention to food cues through either active or passive food preparation, versus attention away from food cues through a non-food distraction task on eating behaviour using a preload/taste test design. Female participants (n = 80) were randomly allocated to one of four conditions: active food preparation (making a wrap); passive video preparation (watching video of researcher making a wrap); distraction (a non-food colouring task); no time control. Measures of desire to eat (hunger, fullness, motivation) were taken before and after the interventions. Food intake was measured in terms of mass of wrap consumed and snacks consumed at a subsequent taste test. The results showed greater wrap consumption for active and passive food preparation and the control groups compared to the distraction intervention. Further, the results showed that active food preparation resulted in increased hunger and motivation to eat and that passive food preparation resulted in increased motivation to eat. No changes were found following distraction. To conclude, attention to food cues through both active and passive food preparation can increase both food intake and the desire to eat. The implications for promoting changes in eating behaviour are discussed.

Binge Eating Disorder: A Psychiatrist's Commentary on Clinical Considerations

PURPOSE

Of the 3 major eating disorders, anorexia nervosa, bulimia nervosa, and binge eating disorder (BED), BED is the most common and exists in the practices of most primary care and psychiatric clinicians. However, BED often goes unrecognized and thus untreated.

METHODS

Reviewed in this commentary are the basic elements in the diagnosis of BED, demographic and clinical characteristics, screening options, the importance of comorbidities, pathophysiology, and available treatments.

FINDINGS

Psychological treatments, including cognitive-behavioral therapy, interpersonal therapy, and behavioral weight loss, have been recommended as first-line options and are supported by several different meta-analytic reviews. Lisdexamfetamine is currently the only medication approved by the US Food and Drug Administration for the treatment of BED. Effect sizes for lisdexamfetamine versus placebo for response, remission, and avoidance of relapse in BED are robust, but its use may be limited by tolerability. This is also the case for topiramate, an anticonvulsant that has been used "off-label" to treat BED.

IMPLICATIONS

Additional medication choices approved by the US Food and Drug Administration for the treatment of BED are needed. Moving forward, opportunities to leverage modern technology to broaden access to treatment are highly desirable.

Conceptualizing eating disorder psychopathology using an anxiety disorders framework: Evidence and implications for exposure-based clinical research

Eating disorders (EDs) and anxiety disorders (ADs) evidence shared risk and significant comorbidity. Recent advances in understanding of anxiety-based disorders may have direct application to research and treatment efforts for EDs. The current review presents an up-to-date, behavioral conceptualization of the overlap between anxiety-based disorders and EDs. We identify ways in which anxiety presents in EDs, consider differences between EDs and ADs relevant to treatment adaptions, discuss how exposure-based strategies may be adapted for use in ED treatment, and outline directions for future mechanistic, translational, and clinical ED research from this perspective. Important research directions include: simultaneous examination of the extent to which EDs are characterized by aberrant avoidance-, reward-, and/or habit-based neurobiological and behavioral processes; improvement in understanding of how nutritional status interacts with neurobiological characteristics of EDs; incorporation of a growing knowledge of biobehavioral signatures in ED treatment planning; development of more comprehensive exposure-based treatment approaches for EDs; testing whether certain exposure interventions for AD are appropriate for EDs; and improvement in clinician self-efficacy and ability to use exposure therapy for EDs.

Role of childhood maltreatment on weight and weight-related behaviors in adulthood

OBJECTIVE

This study investigated associations between child maltreatment and body mass, body weight perceptions, and weight control behaviors among men and women.

METHOD

Data were derived from the National Longitudinal Study of Adolescent to Adult Health (Add Health). Multinomial logistic regression was used to investigate links between dimensions of childhood maltreatment and adult (a) classifications of body mass index (BMI), (b) discrepancies in perceived weight and actual BMI categories, and (c) normative and risky weight control behaviors.

RESULTS

Childhood maltreatment was highly predictive of BMI classification, weight perception discrepancies, and weight control behaviors for women. Women who reported physical abuse, sexual abuse, and neglect had increased risks for being slightly or very overweight, and among those who reported physical abuse and/or a combination of physical abuse and neglect, there is an increased likelihood of holding overweight perceptions. Finally, female victims of physical abuse, physical abuse and neglect, and of neglect only were more likely to adopt risky (e.g., diet pills or purging) versus normative (e.g., diet and exercise) weight control behaviors.

CONCLUSION

Results indicated that women who reported childhood maltreatment have increased risks for developing body and weight related issues, confirming research documenting female-specific effects of childhood maltreatment. For women, certain forms of maltreatment strongly predicted BMI groupings, discrepant weight perceptions, and risky weight behaviors. Taken together, findings suggest that child maltreatment is a predictor of health-related outcomes. Moreover, results highlight the importance of assessing gender-specific effects when examining outcomes related to body, weight, and dieting. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Mediating role of depressive symptoms linking insecure attachment and disordered eating in adolescents: A multiwave longitudinal study

Research has supported a link between insecure attachment and disordered eating in adolescents; however, how this influence is exerted remains unclear. This study explored whether depressive symptoms constitute a pathway through which insecure attachment to parents predicts subsequent development of disordered eating in the transition from childhood to adolescence. The study also examines whether there are differential effects regarding the attachment figure, child's gender, or reciprocity between variables. A community-based sample of Spanish youth (n = 904; 49.4% girls) was followed biennially from age 10 to 16 years. Attachment, depressive symptoms, and disordered eating were measured using the Inventory of Parental and Peer Attachment, Children's Depression Inventory, and Children's Eating Attitudes Test, respectively. Prospective data were analyzed using a dynamic panel model, which accounts for unmeasured time-invariant factors. Whereas insecure attachment to the father did not predict later depression or disordered eating, higher insecure attachment to the mother at ages 10 and 12 years predicted more disordered eating at ages 14 and 16 years via increased depressive symptoms at ages 12 and 14 years. No child's gender-specific or reverse mediational effects were found. This study suggests that an increase in depressive symptoms might be one mechanism by which insecure attachment exerts its influence on the development of eating disorders symptomatology in adolescence. Intervention efforts aimed at strengthening particularly the mother-child attachment relationship may reduce the vulnerability to develop depressive symptoms and disordered eating.

Examination of the shared genetic basis of anorexia nervosa and obsessive-compulsive disorder

Anorexia nervosa (AN) and obsessive-compulsive disorder (OCD) are often comorbid and likely to share genetic risk factors. Hence, we examine their shared genetic background using a cross-disorder GWAS meta-analysis of 3495 AN cases, 2688 OCD cases, and 18,013 controls. We confirmed a high genetic correlation between AN and OCD (r_g = 0.49 ± 0.13, p = 9.07 × 10^-7) and a sizable SNP heritability (SNP h² = 0.21 ± 0.02) for the cross-disorder phenotype. Although no individual loci reached genome-wide significance, the cross-disorder phenotype showed strong positive genetic correlations with other psychiatric phenotypes (e.g., r_g = 0.36 with bipolar disorder and 0.34 with neuroticism) and negative genetic correlations with metabolic phenotypes (e.g., r_g = -0.25 with body mass index and -0.20 with triglycerides). Follow-up analyses revealed that although AN and OCD overlap heavily in their shared risk with other psychiatric phenotypes, the relationship with metabolic and anthropometric traits is markedly stronger for AN than for OCD. We further tested whether shared genetic risk for AN/OCD was associated with particular tissue or cell-type gene expression patterns and found that the basal ganglia and medium spiny neurons were most enriched for AN-OCD risk, consistent with neurobiological findings for both disorders. Our results confirm and extend genetic epidemiological findings of shared risk between AN and OCD and suggest that larger GWASs are warranted.

Community-Based Prevention Programs for Disordered Eating and Obesity: Updates and Current Limitations

PURPOSE OF REVIEW

To review the status of community-based disordered eating and obesity prevention programs from 2014 to 2019.

RECENT FINDINGS

In the last 5 years, prevention programs have found success in intervening with children and parental figures in wellness centers, physical activity centers, childcare centers, workplaces, online, and over-the-phone through directly reducing disordered eating and obesity or by targeting risk factors of disordered eating and obesity. Community-based prevention programs for disordered eating and programs targeting both disordered eating and obesity were scarce, highlighting the critical need for the development of these programs. Qualities of the most effective programs were those in which parents and children were educated on physical activity and nutrition via multiple group-based sessions. Limitations of current prevention programs include few programs targeting high-risk populations, a dearth of trained community members serving as facilitators, inconsistent reporting of adherence rates, and few direct measurements of disordered eating and obesity, as well as few long-term follow-ups, precluding the evaluation of sustained effectiveness.

A review of binge eating disorder and obesity

Binge eating disorder (BED) is a mental illness characterised by recurrent binge eating episodes in the absence of appropriate compensatory behaviours. Consequently, BED is strongly associated with obesity. The current review aims to provide an update of the most relevant aspects of BED (e.g., clinical profile, aetiology and treatment approaches), in order not only to facilitate a better understanding of the disorder and its clinical consequences, but also to identify potential targets of prevention and intervention. Patients with BED often present high comorbidity with other medical conditions and psychiatric disorders. Numerous risk factors have been associated with the development and maintenance of the disorder. Moreover, although some treatments for BED have proven to be effective in addressing different key aspects of the disorder, the rates of patients that have ever received specific treatment for BED are very low. The factors involved and how to implement effective treatments will be discussed for the purpose of addressing the eating symptomatology and comorbid obesity.

Pre-clinical models of reward deficiency syndrome: A behavioral octopus

Individuals with mood disorders or with addiction, impulsivity and some personality disorders can share in common a dysfunction in how the brain perceives reward, where processing of natural endorphins or the response to exogenous dopamine stimulants is impaired. Reward Deficiency Syndrome (RDS) is a polygenic trait with implications that suggest cross-talk between different neurological systems that include the known reward pathway, neuroendocrine systems, and motivational systems. In this review we evaluate well-characterized animal models for their construct validity and as potential models for RDS. Animal models used to study substance use disorder, major depressive disorder (MDD), early life stress, immune dysregulation, attention deficit hyperactivity disorder (ADHD), post traumatic stress disorder (PTSD), compulsive gambling and compulsive eating disorders are discussed. These disorders recruit underlying reward deficiency mechanisms in multiple brain centers. Because of the widespread and remarkable array of associated/overlapping behavioral manifestations with a common root of hypodopaminergia, the basic endophenotype recognized as RDS is indeed likened to a behavioral octopus. We conclude this review with a look ahead on how these models can be used to investigate potential therapeutics that target the underlying common deficiency.

Etiologic and treatment conceptualizations of disordered eating symptoms among mainland Chinese therapists

OBJECTIVE

Reports of disordered eating are increasing in mainland China; however, little is known regarding Chinese psychotherapists' conceptualizations of disordered eating symptomatology. This study explores Chinese psychotherapists' conceptualizations of binge eating (BE)/vomiting symptoms and treatment considerations.

METHOD

In-depth, semi-structured interviews were conducted with mainland Chinese psychotherapists (N = 41) in Mandarin. Participants were given a hypothetical case and provided their conceptualization of the patient's BE/vomiting etiology and treatment recommendations. Etiological conceptualizations were coded using directed content analysis, and treatment recommendations were grouped by intervention strategy.

RESULTS

Participants described psychosocial risk factors for BE/vomiting including intrapersonal characteristics and the childhood family environment, but rarely discussed genetic and neurobiological factors. Few participants reported that they would prioritize the BE/vomiting symptoms in treatment and their specific treatment recommendations varied widely.

DISCUSSION

Most research on BE/vomiting behaviors in the literature is based on Western samples with little attention to mainland Chinese populations. Participants in this study provided conceptualizations of risk factors and treatment recommendations that could generally find evidence in the existing Western literature, even if some theories are no longer supported by updated Western research and the participants focused primarily on psychosocial risks as opposed to genetic/neurobiological factors. It will be important for future research to ascertain mainland Chinese therapists' understanding of these additional types of risk. These findings also suggest a disconnect between clinical findings on neurobiological risks and Chinese therapists' knowledge and/or perceived clinical utility of these risks. Implications for treatment and research dissemination to diverse global communities are discussed.

A proposed synergistic effect of CSF1R and NMUR2 variants contributes to binge eating in hereditary diffuse leukoencephalopathy with spheroids

Background

The genetic mechanisms of binge eating (BE) as a disease identity remain obscure. BE is usually viewed as a part of the behavioral variant of frontotemporal dementia (bvFTD) features. We encountered a family with hereditary diffuse leukoencephalopathy with spheroids (HDLS) that manifested uniformly with binge-eating-onset dementia. The genetic factors associated with the rare phenotype were investigated.

Methods

The detailed phenotypes of the patients were described. We performed whole-exome sequencing (WES) of family members and repeat-primed PCR to analyze the patients' expansion size of C9orf72, a well-established gene causing FTD. The WES results of additional HDLS patients without BE manifestations were also investigated.

Results

All affected individuals had a BE-dementia-epilepsy pattern of disease progression. A recurrent disease-causing mutation in CSF1R established the diagnosis of HDLS in the family. No abnormalities in the expansion size of C9orf72 were detected. The concurrence of a recurrent CSF1R mutation and a rare variant in NMUR2, a gene functionally related to BE, was revealed in the affected family members. No potentially pathogenic variants in other known BE-associated genes were identified. Both the NMUR2 variant and the CSF1R mutation cosegregated with the BE-dementia-epilepsy phenotype in the family. In three additional HDLS patients without BE, no pathogenic variants in NMUR2 were detected.

Conclusions

We propose that synergistic genetic effects of NMUR2 and CSF1R variants may exist and contribute to the development of the BE phenotype in HDLS. NMUR2 is one of the potential susceptible genes in BE and may contribute in a background of a disrupted structural neuronetwork. Further studies in other BE-related disorders are required.

Estimation of Eating Disorders Prevalence by Age and Associations With Mortality in a Simulated Nationally Representative US Cohort

IMPORTANCE

Eating disorders (EDs) are common psychiatric disorders associated with high mortality. However, data on ED disease dynamics and treatment coverage are sparse.

OBJECTIVES

To model the individual-level disease dynamics of ED from birth to age 40 years and to estimate the association of increased treatment coverage with ED-related mortality.

DESIGN, SETTING, AND PARTICIPANTS

In this decision analytical model study, an individual-level Markov state transition model was empirically calibrated in April 2019 using a Bayesian approach to synthesize available clinical and epidemiologic ED data. The simulation model was calibrated to nationally representative US survey data from 2007 and 2011. A virtual cohort of 100 000 individuals (50 000 [50%] male) was modeled from birth to age 40 years for 4 ED diagnoses: anorexia nervosa, bulimia nervosa, binge eating disorder, and other specified feeding and eating disorders.

EXPOSURES

Age-specific ED incidence and mortality rates and background (all-cause) mortality.

MAIN OUTCOMES AND MEASURES

The main outcomes were age-specific 12-month and lifetime ED prevalence and number of deaths per 100 000 general population individuals by age 40 years. The mean and 95% uncertainty intervals (UIs) of 1000 simulations, accounting for stochastic and parameter uncertainty, are reported.

RESULTS

The highest estimated mean annual prevalence of ED occurred at approximately age 21 years for both male individuals (7.4%; 95% UI, 3.5%-11.5%) and female individuals (10.3%; 95% UI, 7.0%-14.2%), with lifetime mean prevalence estimates increasing to 14.3% (95% UI, 9.7%-19.0%) for male individuals and 19.7% (95% UI, 15.8%-23.9%) for female individuals by age 40 years. Ninety-five percent of first-time cases occurred by age 25 years. Current treatment coverage averts an estimated mean of 41.7 deaths per 100 000 people (95% UI, 13.0-82.0 deaths per 100 000 people) by age 40 years, whereas increasing treatment coverage for all patients with ED could avert an estimated mean of 70.5 deaths per 100 000 people by age 40 years (95% UI, 26.0-143.0 deaths per 100 000 people).

CONCLUSIONS AND RELEVANCE

In this simulation modeling study, the estimated lifetime prevalence of ED was high, with approximately 1 in 7 male and 1 in 5 female individuals having an ED by age 40 years. The initial onset of EDs was highly concentrated during adolescence and young adulthood, suggesting that this is a critical period for prevention efforts. However, the high estimated prevalence of recurring ED later in life highlights the importance of identification and treatment of ED at older ages as well. These findings suggest that increasing treatment coverage could substantially reduce ED-related mortality.

The Role of Puberty and Ovarian Hormones in the Genetic Diathesis of Eating Disorders in Females

Puberty is a critical risk period for eating disorders (EDs). ED incidence increases across the pubertal period and becomes female predominant, and genetic influences on disordered eating significantly increase. Surges of ovarian hormones, particularly estrogen, may drive this increasing genetic effect for EDs in pubertal girls and contribute to differential phenotypic presentations beyond puberty. In this article, we explain phenotypic associations between puberty and disordered eating and present evidence showing underlying genetic and hormonal influence. Potential benefits of communicating roles of genetic influence to people with or at risk for EDs are also discussed.

Understanding the genetics and epigenetics of bulimia nervosa/bulimia spectrum disorder and comorbid borderline personality disorder (BN/BSD-BPD): a systematic review

PURPOSE

To evaluate and understand the genetic and epigenetic basis of bulimia nervosa/bulimia spectrum disorder and comorbid borderline personality disorder (BN/BSD-BPD).

METHODS

The present systematic review was conducted in accordance to PRISMA guidelines. Advanced systematic searches of Medline, EMBASE, PsychINFO, Web of Science, Scopus, CINHAL plus, and the Cochrane Library were conducted using the search terms 'bulimia nervosa', 'bulimia spectrum disorder', 'borderline personality disorder', 'genes', and 'genetics'. The search strategy garnered seven studies for inclusion in the present review.

RESULTS

Women with BN/BSD-BPD had significantly lower serotonin and monoamine oxidise activity compared to women with BN/BSD or healthy controls (HC). As well, women with BN/BSD-BPD displayed elevated methylation of the dopamine receptor gene promoter, brain-derived neurotrophic factor, and changes in the methylation of the glucocorticoid receptor gene promoter (NR3C1) compared to women with BN/BSD and HC. The results also demonstrated that rates of childhood sexual abuse and childhood physical abuse are higher in those with BN/BSD-BPD than those with BN/BSD and HC, and that these types of abuse are often correlated with the methylation differences seen in BN/BSD-BPD women.

CONCLUSION

Due to the differences observed between individuals with BN/BSD-BPD and those with BN/BSD and HC a genetic/epigenetic aetiological model of BN/BSD-BPD was developed and is proposed in this review. This evidence-based model visually illustrates the current state of the field and draws attention to the need for subsequent research.

Binge eating disorder revisited: what's new, what's different, what's next

Binge eating disorder (BED) is the most common type of eating disorder. According to the most recent data available, the estimated lifetime prevalence of BED among US adults in the general population is 0.85% (men 0.42% and women 1.25%). Among psychiatric treatment populations, prevalence is several-fold higher. Although many people with BED are obese (BMI ≥ 30 kg/m2), roughly half are not. In the DSM-5, BED is defined by recurrent episodes of binge eating (eating in a discrete period of time, an amount of food larger than most people would eat in a similar amount of time under similar circumstances and a sense of lack of control over eating during the episode), occurring on average at least once a week for 3 months, and associated with marked distress. BED often goes unrecognized and thus untreated; in one study, 344 of 22,387 (1.5%) survey respondents met DSM-5 criteria for BED, but only 11 out of the 344 had ever been diagnosed with BED by a health-care provider. Psychiatric comorbidities are very common, with most adults with BED also experiencing anxiety disorders, mood disorders, impulse control disorders, or substance use disorders, suggesting that clinicians have patients in their practice with unrecognized BED. Multiple neurobiological explanations have been suggested for BED, including dysregulation in reward center and impulse control circuitry. Additionally, there is interplay between genetic influences and environmental stressors. Psychological treatments such as cognitive behavioral interventions have been recommended as first line and are supported by meta-analytic reviews; however, access to such treatments may be limited because of local availability and/or cost, and these treatments generally lead to little to no weight loss, although successfully eliminating binge eating can protect against future weight gain. Routine medication treatments for anxiety and depression do not necessarily ameliorate the symptoms of BED, but there are approved and emerging medication options, lisdexamfetamine and dasotraline, respectively, that specifically address the core drivers behind binge eating, namely obsessive thoughts and compulsive behaviors regarding food, resulting in marked decreases in binge eating behaviors as well as weight loss.

Genetic association analysis of 5-HTR2A gene variants in eating disorders in a Mexican population

INTRODUCTION

The 5-HTR2A gene has been implicated as candidate gene for eating disorders. The aim of the present study was to analyze the association of rs6311 and rs6313 polymorphisms of 5-HTR2A gene with eating disorders in Mexican population, and to evaluate if the polymorphisms of 5-HTR2A gene were associated with comorbidities in eating behavior.

METHODS

We conducted a case-control analysis with 460 subjects. We included 168 patients with eating disorders and 292 controls; two polymorphisms of 5-HTR2A gene were genotyped. We assessed the association by allele, genotype, and inheritance models. Psychiatric comorbidities were analyzed by genotype in patients with eating disorders.

RESULTS

We found an association between rs6311 and eating disorders in a Mexican population by allele (OR = 8.09; 95% CI = 5.99-11.03; p = 2.2e-16) and genotype (OR = 76.14; 95% CI = 35.61-177.18; p = 2.2e-16). Individuals who carried GG genotype showed increased risk for suicide attempted (OR = 2.14; CI = 1.10-4.26; p = 0.035) as comorbidity associated with eating disorders. No positive associations were observed for rs6313 polymorphism.

CONCLUSION

Our results showed an association of rs6311 (A1438G) polymorphism of 5-HTR2A gene with eating disorders, and these polymorphic variants could increase the risk of psychiatric comorbidities. However, more studies are required to replicate the results and to reach to a conclusive association between eating disorders and rs6311.

Variation in the Oxytocin Receptor Gene Is Associated With Social Cognition and ADHD

OBJECTIVE

Children with ADHD show substantial deficits in social cognitive abilities. Oxytocin, mediated through its specific receptor (OXTR), is involved in the regulation of social behavior and social cognition.

METHOD

The entire coding sequence of the human OXT and OXTR genes were sequenced to identify mutations and single nucleotide polymorphisms (SNPs) in 151 children with ADHD (ADHD-combined, n = 51; inattentive subtype, n = 50; ADHD-C plus conduct disorder [CD], n = 50; 11-18 years) and 100 healthy controls.

RESULTS

We examined the association of three detected SNPs of OXTR with social cognition deficits. A significant association was shown between the children with ADHD and children with CT/TT genotypes of rs4686302 (χ² = 3.695; p = .037). ADHD children with CT/TT genotype for the OXTR rs4686302 performed significantly lower on the facial emotion recognition task than those with CC genotype.

CONCLUSION

OXTR rs4686302 polymorphism was shown to be a genetic marker in social cognition deficits in ADHD children.

Body dissatisfaction in adolescent boys

Body dissatisfaction is a significant mental health symptom present in adolescent girls and boys. However, it is often either disregarded in adolescent boys or examined using assessments that may not resonate with males. The present study addresses these issues, examining the manifestation, etiology, and correlates of 3 facets of body dissatisfaction in adolescent boys. Adolescent male twins aged 16- to 17-years-old from the Swedish Twin Study of Child and Adolescent Development were included along with a female comparison group: 915 monozygotic and 671 dizygotic same-sex twins. Body dissatisfaction was defined using measures of height dissatisfaction, muscle dissatisfaction, and the body dissatisfaction subscale of the Eating Disorder Inventory (EDI-BD). We examined the prevalence of body dissatisfaction, whether the facets of body dissatisfaction were phenotypically and etiologically distinct, and associations with specific externalizing and internalizing symptoms. For boys, muscle dissatisfaction scores were greater than height dissatisfaction scores. Results also indicated that height and muscle dissatisfaction were phenotypically and etiologically distinct from the EDI-BD. Unique associations were observed with externalizing and internalizing symptoms: muscle dissatisfaction with symptoms of bulimia nervosa and the EDI-BD with internalizing symptoms, body mass index, and drive for thinness. The facets of body dissatisfaction were also largely distinct in girls and unique between-sex associations with externalizing and internalizing symptoms emerged. Overall, male-oriented aspects of body dissatisfaction are distinct from female-oriented aspects of body dissatisfaction. To capture the full picture of male body dissatisfaction, multiple facets must be addressed. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Loss-of-Control Eating and Obesity Among Children and Adolescents

PURPOSE OF REVIEW

This review summarizes findings on pediatric loss-of-control (LOC) eating and obesity published since 2013 in relation to physiological, socioenvironmental, and psychological factors.

RECENT FINDINGS

LOC eating and obesity are highly comorbid in youth. Genetic and physiological risk factors are associated with the development of LOC eating. Adverse physiological outcomes of LOC eating include increased risk for overweight and obesity and greater dysfunction in components of metabolic syndrome. Socioenvironmental, psychological, and behavioral factors, such as weight-based teasing, dieting, negative affect, emotion dysregulation, and aspects of cognitive functioning, are consistently related to LOC eating in youth, independent of weight. Prospectively, LOC eating may predict the onset of anxiety disorders, depression, and more severe eating psychopathology later in life. Updates on interventions and future directions are discussed. LOC eating may be a key symptom to target adverse physiological and psychological outcomes; however, treatments are limited and require further examination.

Are Eating Disorders and Related Symptoms Risk Factors for Suicidal Thoughts and Behaviors? A Meta-analysis

This meta-analysis addressed whether eating disorders (EDs) are risk factors (i.e., longitudinal predictors) for suicidal thoughts and behaviors. We identified 2,611 longitudinal studies published through August 1, 2017. Inclusion required studies include at least one longitudinal analysis predicting suicide ideation, attempt, or death using an ED diagnosis and/or symptom. Fourteen studies (42 prediction cases) met criteria. Results indicated that clinically diagnosed EDs and disordered eating symptoms were significant but weak predictors of suicide attempts but not death. Effects remained weak when moderators were considered. By reviewing the methodological limitations of previous research, these results highlight avenues for future research.

Genetic risk factors for eating disorders: an update and insights into pathophysiology

Genome-wide-association studies (GWASs), epigenetic, gene-expression and gene-gene interaction projects, nutritional genomics and investigations of the gut microbiota have increased our knowledge of the pathophysiology of eating disorders (EDs). However, compared with anorexia nervosa, genetic studies in patients with bulimia nervosa and binge-eating disorder are relatively scarce, with the exception of a few formal genetic and small-sized candidate-gene-association studies. In this article, we review important findings derived from formal and molecular genetics in order to outline a genetics-based pathophysiological model of EDs. This model takes into account environmental and nutritional factors, genetic factors related to the microbiome, the metabolic and endocrine system, the immune system, and the brain, in addition to phenotypical traits of EDs. Shortcomings and advantages of genetic research in EDs are discussed against the historical background, but also in light of potential future treatment options for patients with EDs.

Validation of the Arabic version of the binge eating scale and correlates of binge eating disorder among a sample of the Lebanese population

OBJECTIVES

To test the psychometric properties of the Arabic version of the Binge Eating Scale (BES), a self-questionnaire assessing binge eating, in a sample of the Lebanese population. The secondary objective was to evaluate factors associated with binge eating.

METHODS

This cross-sectional study, conducted between January and May 2018, enrolled 811 adult participants from all districts of Lebanon. The BES was administered to study its psychometric properties. The sample was divided into two separate samples (405 for sample 1 and 406 for sample 2). An exploratory factor analysis was executed on Sample 1, followed by a confirmatory factor analysis on Sample 2 using the structure obtained in Sample 1. Three hierarchical stepwise linear regressions were conducted to assess factors associated with binge eating.

RESULTS

The factor analysis suggested a two-factor structure for the BES explaining a total of 41.4% of the variance. All items could be extracted from the list. The internal consistency of the measurement was adequate (Cronbach's alpha = 0.86). The confirmatory factor analysis revealed an adequate fit to the model with satisfactory Maximum Likelihood Chi-Square/Degrees of Freedom (χ²/df), Steiger-Lind RMSEA, Joreskog GFI, and AGFI. Higher BMI, depression, anxiety, emotional eating, greater body dissatisfaction, and more pressure from media to lose weight were associated with higher binge eating. Higher expressive suppression facet score was associated with lower binge eating.

CONCLUSION

The Arabic version of BES could be a useful tool for screening and assessing the binge eating behaviors in clinical practice and research. Also, being dissatisfied with one's body size, having a history of sexual abuse, family history of binge eating, increased depressive/anxiety symptoms, and lower self-esteem seem to be associated with higher BES scores.

Genetic Markers in Psychiatry

Psychiatric disorders such as addiction (substance use and addictive disorders), depression, eating disorders, schizophrenia, and post-traumatic stress disorder (PTSD) are severe, complex, multifactorial mental disorders that carry a high social impact, enormous public health costs, and various comorbidities as well as premature morbidity. Their neurobiological foundation is still not clear. Therefore, it is difficult to uncover new set of genes and possible genetic markers of these disorders since the understanding of the molecular imbalance leading to these disorders is not complete. The integrative approach is needed which will combine genomics and epigenomics; evaluate epigenetic influence on genes and their influence on neuropeptides, neurotransmitters, and hormones; examine gene × gene and gene × environment interplay; and identify abnormalities contributing to development of these disorders. Therefore, novel genetic approaches based on systems biology focused on improvement of the identification of the biological underpinnings might offer genetic markers of addiction, depression, eating disorders, schizophrenia, and PTSD. These markers might be used for early prediction, detection of the risk to develop these disorders, novel subtypes of the diseases and tailored, personalized approach to therapy.

Association of Leptin Gene DNA Methylation With Diagnosis and Treatment Outcome of Anorexia Nervosa

Epigenetic alterations are increasingly implicated in the pathophysiology of anorexia nervosa (AN) but are as yet poorly understood. We investigated possible associations between the leptin gene (LEP) and the leptin receptor gene (LEPR) DNA promoter methylation and (1) a diagnosis of AN and (2) outcome after a 10 months psychotherapeutic outpatient treatment. 129 (LEPR: n = 135) patients with AN were investigated during the large scale psychotherapeutic Anorexia Nervosa Treatment Outpatient Study (ANTOP) trial, compared to 117 (LEPR: n = 119) age and height matched, normal-weight healthy controls. Blood samples were taken at baseline, the end of therapy (40 weeks) and the 12-months follow-up and compared to controls. Methylation was measured in whole blood via bisulfite sequencing. Within the promoter region 32 (LEP) and 39 CpG sites (LEPR) were analyzed. Two key findings were observed. First, LEP and LEPR methylation at baseline were lower in patients compared to controls (LEP: [%] AN: 30.94 ± 13.2 vs. controls: 34.53 ± 14.6); LEPR ([%] AN: 3.73 ± 5.4 vs. controls: 5.22 ± 8.3, mixed linear models: both P < 0.001). Second, lower DNA methylation of the LEP promoter, with a dynamic upregulation during treatment, was associated with a full recovery in AN patients (% change from baseline to follow-up in full recovery patients: +35.13% (SD: 47.56); mixed linear model: P < 0.0001). To test for potential predictive properties of mean LEP DNA methylation a LEP DNA methylation cut-off (31.25% DNA methylation) was calculated, which significantly discriminated full recovery vs. full syndrome AN patients. This cut-off was then tested in a group of previously unclassified patients (missing follow-up data of the Structured Interview for Anorexic and Bulimic disorders; n = 33). Patients below the cut-off (31.25% LEP DNA methylation) showed an increase in BMI over time, while those above the cut-off had a decrease in BMI (ANOVA at the 12-months follow-up: P = 0.0142). To our knowledge, this is the first study investigating epigenetic alterations in AN over time. Our findings indicate that LEP DNA methylation might be involved in the disease course of AN.

Effects of fat mass and obesity-associated (FTO) gene polymorphisms on binge eating in women with binge-eating disorder: The moderating influence of attachment style

OBJECTIVES

The genetics of binge-eating disorder (BED) is an emerging topic and one candidate pathway, namely the fat mass and obesity-associated (FTO) gene, may be implicated because of its role in food reward sensitivity and self-regulation of eating. The aims of this study were to examine the independent effects of variants of FTO on binge frequency in women with and without BED and to examine the moderating role of interpersonal attachment in this association.

METHODS

Secondary data analysis was conducted on a cross-sectional comparison of three groups of women in a trial of group treatment for BED: BED with obesity (n = 73), BED without obesity (n = 55), and normal weight without BED (n = 50). Women were genotyped for five of the most common FTO single-nucleotide polymorphisms, rs9939609, rs8050136, rs3751812, rs1421085, and rs1121980, which have been related to body mass index and energy intake. Binge frequency (Eating Disorder Examination), body composition (bioelectric impedance), and attachment (Attachment Style Questionnaire) were assessed.

RESULTS

There were no significant between-group differences for frequencies of FTO alleles, nor were there any significant anthropometric associations. The FTO × attachment interaction was significant whereby, relative to a low-risk FTO genotype, individuals with a high-risk genotype for the SNP rs1421085 and high-avoidant attachment had higher mean binge frequency than those with high genetic risk but low-avoidant attachment (β = -7.96; t = -2.07; P = 0.042).

CONCLUSIONS

FTO genotypes associated with risk for obesity and loss of control of eating, specifically rs1421085, may interact with insecure attachment in a way that may exacerbate binge eating among women with BED.