A systematic review on the role of microbiota in the pathogenesis and treatment of eating disorders

Exploring biologically oriented precision mental health initiatives for the care of patients with eating disorders: A narrative review

OBJECTIVE

Eating disorders (EDs) represent a major public health burden. Increasingly, studies suggest mental health (MH) fields are failing to improve the effectiveness of treatments and that alternative models of care must be considered. Precision mental health (PMH) seeks to tailor treatment to individual needs and relies on a comprehensive understanding of the neurobiological and physiological underpinnings of mental illness.

METHODS

In this narrative review, published literature with focus on biological application of PMH strategies for EDs is reviewed and summarised.

RESULTS

A total of 39 articles were retained for the review covering a variety of themes with relevance to PMH. Many studies of biological markers with PMH applicability focused on anorexia nervosa. Although a variety of potential PMH research applications were identified, the review failed to identify any evidence of implementation into routine ED practice.

CONCLUSIONS

Despite the theoretical merit of biological application of PMH in ED treatment, clinical applications for standard practice are lacking. There is a need to invest further in studies that seek to identify biological markers and investigate neurobiological underpinnings of disease in hopes of targeting and developing treatments that can be better tailored to the individualised needs of patients.

Sympathovagal quotient and resting-state functional connectivity of control networks are related to gut Ruminococcaceae abundance in healthy men

INTRODUCTION

Heart rate variability (HRV), brain resting-state functional connectivity (rsFC), and gut microbiota (GM) are three recognized indicators of health status, whose relationship has not been characterized. We aimed to identify the GM genera and families related to HRV and rsFC, the interaction effect of HRV and rsFC on GM taxa abundance, and the mediation effect of diet on these relationships.

METHODS

Eighty-eight healthy, young Colombian men were included in this cross-sectional study. HRV metrics were extracted from 24-hour Holter monitoring data and the resting functional connectivity strength (FCS) of 15 networks were derived from functional magnetic resonance imaging. Gut microbiota composition was assessed using the sequences of the V3-V4 regions of the 16 S rRNA gene, and diet was evaluated using a food frequency questionnaire. Multivariate linear regression analyses were performed to evaluate the correlations between the independent variables (HRV metrics and FCS) and the dependent variables (GM taxa abundance or alpha diversity indexes). Mediation analyses were used to test the role of diet in the relationship between HRV and GM.

RESULTS

The sympathovagal quotient (SQ) and the FCS of control networks were positively correlated with the abundance of the gut Ruminococcaceae family and an unclassified Ruminococcaceae genus (Ruminococcaceae_unc). Additionally, the interaction between the FCS of the control network and SQ reduced the individual main effects on the Ruminococcaceae_unc abundance. Finally, reduced habitual fiber intake partially mediated the relationship between SQ and this genus.

CONCLUSION

Two indicators of self-regulation, HRV and the rsFC of control networks, are related to the abundance of gut microbiota taxa in healthy men. However, only HRV is related to habitual dietary intake; thus, HRV could serve as a marker of food choice and GM composition in the future.

Mapping Treatment Advances in the Neurobiology of Binge Eating Disorder: A Concept Paper

Binge eating disorder (BED) is a complex and heritable mental health disorder, with genetic, neurobiological, neuroendocrinological, environmental and developmental factors all demonstrated to contribute to the aetiology of this illness. Although psychotherapy is the gold standard for treating BED, a significant subgroup of those treated do not recover. Neurobiological research highlights aberrances in neural regions associated with reward processing, emotion processing, self-regulation and executive function processes, which are clear therapeutic targets for future treatment frameworks. Evidence is emerging of the microbiota-gut-brain axis, which may mediate energy balance, high-lighting a possible underlying pathogenesis factor of BED, and provides a potential therapeutic strategy.

Macauba (Acrocomia aculeata) pulp oil has the potential to enhance the intestinal barrier morphology, goblet cell proliferation and gut microbiota composition in mice fed a high-fat diet

Macauba (Acrocomia aculeata) is a palm tree native from Brazil, whose pulp is rich in oil that has a high content of oleic acid and carotenoids. Macauba pulp oil can bring health benefits due to its bioactive compounds; however, its effects on gut health are unknown. Thus, the objective of this study was to evaluate the effect of macauba pulp oil on the intestinal health in mice fed a high-fat (HF) diet. Male C57BL1/6 mice were randomly divided into three groups (10 animals/group): control diet, HF diet and HF diet with 4 % of macauba pulp oil (HFM). Concentration of short-chain fatty acids (SCFA), faecal pH and histomorphometric analysis of the colon were performed. Content of colon samples was used on microbiome analysis using 16S rRNA amplicon sequencing. Animals from the HFM group had higher butyric acid content and goblet cells number, greater circular and longitudinal muscle layer and higher α-diversity compared with the HF group. Moreover, consumption of MPO reduced Desulfobacterota phylum, Ruminococcaceae, Oscillospiraceae, Prevotellaceae, Bifidobacteriaceae family, Faecalibacterium, Prevotella, Ruminococcus and Enterorhabdus genus. Therefore, macauba pulp oil was able to modulate the gut microbiota and enhance intestinal barrier morphology, showing preventive effects on gut dysbiosis in mice fed a HF diet.

Systematic identification of the role of gut microbiota in mental disorders: a TwinsUK cohort study

Mental disorders are complex disorders influenced by multiple genetic, environmental, and biological factors. Specific microbiota imbalances seem to affect mental health status. However, the mechanisms by which microbiota disturbances impact the presence of depression, stress, anxiety, and eating disorders remain poorly understood. Currently, there are no robust biomarkers identified. We proposed a novel pyramid-layer design to accurately identify microbial/metabolomic signatures underlying mental disorders in the TwinsUK registry. Monozygotic and dizygotic twins discordant for mental disorders were screened, in a pairwise manner, for differentially abundant bacterial genera and circulating metabolites. In addition, multivariate analyses were performed, accounting for individual-level confounders. Our pyramid-layer study design allowed us to overcome the limitations of cross-sectional study designs with significant confounder effects and resulted in an association of the abundance of genus Parabacteroides with the diagnosis of mental disorders. Future research should explore the potential role of Parabacteroides as a mediator of mental health status. Our results indicate the potential role of the microbiome as a modifier in mental disorders that might contribute to the development of novel methodologies to assess personal risk and intervention strategies.

Gut Microbiome Changes in Anorexia Nervosa: A Comprehensive Review

Anorexia nervosa (AN) remains a challenging condition in psychiatric management and its pathogenesis is not yet fully understood. An imbalance in the gut microbiota composition may contribute to its pathophysiology. This review aims to explore the link between the human gut microbiota and AN (objective 1) or refeeding syndrome in AN (objective 2). The online databases MEDLINE and PsycINFO were searched for relevant studies. A total of 14 studies met the inclusion and exclusion criteria and only answered objective 1. A total of 476 AN patients, 554 healthy-weight (HC) controls, and 0 patients with other psychiatric disorders were included. Compared to HC, there were consistently reduced abundances of Faecalibacterium prausnitzii and Roseburia inulinivorans, and increased Methanobrevibacter smithii, in AN patients. Changes in alpha diversity were inconsistent, while beta diversity increased in four of six studies. Our model suggests that an imbalance in gut microbiota composition leads to reduced short-chain fatty acids, contributing to a proinflammatory state in AN, which is also common in other psychiatric comorbidities. Microbial changes may also contribute to the semistarvation state through endocrine changes and altered energy utilization.

Probiotic and prebiotic interventions in eating disorders: A narrative review

AIMS

The review aimed to summarise and discuss findings focused on therapeutic probiotic and prebiotic interventions in eating disorders (ED).

METHODS

Using PubMed/MEDLINE, Cochrane Library, and Web of Science all published studies were retrieved until February 2023, following PRISMA guidelines. From the 111 initial studies, 5 met the inclusion criteria for this review.

RESULTS

All studies included in this narrative review were focused on anorexia nervosa (AN). Three longitudinal, randomised, controlled trials aimed to evaluate interventions with probiotics (Lactobacillus reuteri, yoghurt with Lactobacillus, and Streptococcus) in children and adolescents. These studies primarily emphasised medical outcomes and anthropometric measures following the administration of probiotics. However, the findings yielded mixed results in terms of short-term weight gain or alterations in specific immunological parameters. With a lower level of evidence, supplementation with synbiotics (probiotic + prebiotic) has been associated with improvements in microbiota diversity and attenuation of inflammatory responses.

CONCLUSIONS

Research on probiotics and prebiotics in ED is limited, primarily focussing on anorexia nervosa (AN). Their use in AN regarding medical and anthropometric outcomes needs further confirmation and future research should be warranted to assess their impact on psychological and ED symptomatology, where there is a notable gap in the existing literature.

Are probiotics effective in reducing the metabolic side effects of psychiatric medication? A scoping review of evidence from clinical studies

The psychopharmacological treatment of patients with schizophrenia or depression is often accompanied by serious side effects. In particular, the clinical findings of weight gain are worrying, as this side effect can lead to various medical sequelae in the future. However, the treatment of metabolic changes in psychiatric patients is often neglected or unsuccessful. An improved knowledge of possible therapeutic approaches is needed. The aim of this study was to provide an overview of the utilisation and effectiveness of probiotics in reducing weight gain in patients with severe mental illness. A scoping review of studies published until 15 June 2022 was conducted to identify studies using probiotics in people with schizophrenia or depression. We systematically searched the databases EMBASE, PubMed (MEDLINE), Web of Science and SCOPUS with a predefined search string. In addition, reference lists of relevant publications were examined for additional studies. The studies were assessed by two reviewers. The primary outcomes were weight-related measurements. The secondary outcomes were metabolic blood parameters and gut microbiota. Four studies ultimately met the inclusion criteria. Two studies in which probiotics were administered did not find significant effects on pharmacologically induced weight gain. The other two studies examined the effects of synbiotics (a combination of probiotics and prebiotics). Interestingly, less weight gain was observed in individuals with this combined intervention. Adjustments in diet can be helpful and are generally well-accepted interventions in the fight against pharmacologically induced weight gain. The clinical use of probiotics and prebiotics (or synbiotics) as dietary interventions may represent a promising additional strategy in this regard. However, the few studies available showed no clear conclusions.

From gut microbiota to brain: implications on binge eating disorders

The prevalence of eating disorders has been increasing over the last 50 years. Binge eating disorder (BED) and bulimia nervosa (BN) are two typical disabling, costly and life-threatening eating disorders that substantially compromise the physical well-being of individuals while undermining their psychological functioning. The distressing and recurrent episodes of binge eating are commonly observed in both BED and BN; however, they diverge as BN often involves the adoption of inappropriate compensatory behaviors aimed at averting weight gain. Normal eating behavior is coordinated by a well-regulated trade-off between intestinal and central ingestive mechanism. Conversely, despite the fact that the etiology of BED and BN remains incompletely resolved, emerging evidence corroborates the notion that dysbiosis of gastrointestinal microbiome and its metabolites, alteration of gut-brain axis, as well as malfunctioning central circuitry regulating motivation, execution and reward all contribute to the pathology of binge eating. In this review, we aim to outline the current state of knowledge pertaining to the potential mechanisms through which each component of the gut-brain axis participates in binge eating behaviors, and provide insight for the development of microbiome-based therapeutic interventions that hold promise in ameliorating patients afflicted with binge eating disorders.

[Anorexia nervosa, microbiota and brain]

Introduction

Anorexia nervosa (AN) is a psychiatric disease with a high prevalence and comorbidities, characterized by a low response rate to treatment. It is considered as a multifactorial disease. In recent years, the focus has been placed on the presence of intestinal dysbiosis and its possible involvement as a causal factor as well as an alternative treatment. The objective of this work has been to review the current state of knowledge of alterations in the intestinal microbiota identified in patients with AN and the possibility of using probiotics as a therapeutic alternative. Significant changes in the diversity of species associated with weight loss have been described that could favor the perpetuation of the disorder, and that would explain many of the nutritional, gastrointestinal, psychological, and cognitive alterations present in these patients. The use of probiotics, still little studied in patients with AN, sheds some light on this matter to improve the treatment response, always hand in hand with conventional treatments.

Microbiota-gut-brain axis drives overeating disorders

Overeating disorders (ODs), usually stemming from dieting history and stress, remain a pervasive issue in contemporary society, with the pathological mechanisms largely unresolved. Here, we show that alterations in intestinal microbiota are responsible for the excessive intake of palatable foods in OD mice and patients with bulimia nervosa (BN). Stress combined with a history of dieting causes significant changes in the microbiota and the intestinal metabolism, which disinhibit the vagus nerve terminals in the gut and thereby lead to a subsequent hyperactivation of the gut-brain axis passing through the vagus, the solitary tract nucleus, and the paraventricular nucleus of the thalamus. The transplantation of a probiotic Faecalibacterium prausnitzii or dietary supplement of key metabolites restores the activity of the gut-to-brain pathway and thereby alleviates the OD symptoms. Thus, our study delineates how the microbiota-gut-brain axis mediates energy balance, unveils the underlying pathogenesis of the OD, and provides potential therapeutic strategies.

Dysbiosis of gut microbiota during fecal stream diversion in patients with colorectal cancer

BACKGROUND

The effect of fecal stream diversion on the gut microbiota is still uncertain. The present study was designed to assess the effect of fecal stream diversion on the composition of the gut microbiota in patients with colorectal cancer. We included patients undergoing left-sided colorectal cancer surgery with (ileostomy group) or without (control group) diverting ileostomy. Fecal samples were collected from 10 patients in each group before surgery (t1) and after ileostomy repair in the ileostomy group and 6-12 months after the initial surgery in the control group (t2). The fecal microbiota was assessed using 16S rRNA sequencing, and changes in the composition of the fecal microbiota were compared between the two groups.

RESULTS

Alpha diversity analysis revealed that the complexity of fecal microbiota decreased between t1 and t2 only in the ileostomy group. Beta diversity analysis also showed dissimilarity between t1 and t2 only in the ileostomy group. The composition of the microbiota was similar between the two groups at t1. However, at t2, the ileostomy group had lower proportion of beneficial bacteria (Lachnospiraceae, 3.8% vs. 29.9%, p < 0.001; Ruminococcaceae, 0.6% vs. 18.4%, p < 0.001; Blautia, 0.1% vs. 9.1%, p < 0.001; Faecalibacterium, 0.2% vs. 7.5%, p < 0.001) and a higher proportion of harmful bacteria (Proteobacteria, 17.9% vs. 5.1%, p = 0.006; Clostridium, 16.2% vs. 1.1%, p = 0.013; Streptococcus, 17.7% vs. 1.6%, p = 0.002) than the control group.

CONCLUSIONS

Fecal stream diversion was closely associated with less diversity and dysbiosis of the gut microbiota.

The Effect of Dietary Oat Consumption and Its Constituents on Fat Storage and Obesity

This review is to summarize and analyze the currently available knowledge concerning the action of oat (Avena sativa L.) consumption on obesity, as well as possible constituents and extra- and intracellular mediators responsible for its anti-obesity effect. The oat constituents could reduce fat storage via several mediatory mechanisms - brain centers regulating appetite, gastrointestinal functions, gut bacteria, fat synthesis and metabolism and maybe via changes in oxidative processes, steroid hormones receptors and adipose tissue vascularization. Several oat constituents (starch, fiber and beta-glucan) could have anti-obesity properties, whilst one oat constituent (starch or fiber) could affect fat storage via several mechanisms of action.

Gut microbiota metabolites mediate the interplay between childhood maltreatment and psychopathology in patients with eating disorders

Eating disorders (EDs) are syndromes with a multifactorial etiopathogenesis, involving childhood traumatic experiences, as well as biological factors. Human microbiome has been hypothesised to play a fundamental role, impacting on emotion regulation, as well as with eating behaviours through its metabolites such as short chain fatty acids (SCFAs). The present study investigated the interactions between psychopathology of EDs, the gut microbiome and SCFAs resulting from bacterial community metabolic activities in a population of 47 patients with Anorexia Nervosa, Bulimia Nervosa, and Binge Eating Disorder and in healthy controls (HCs). Bacterial gut microbiota composition differences were found between subjects with EDs and HCs, especially in association with different pathological behaviours (binge-purge vs restricting). A mediation model of early trauma and ED-specific psychopathology linked reduction of microbial diversity to a typical microbiota-derived metabolite such as butyric acid. A possible interpretation for this model might be that childhood trauma represents a risk factor for gut dysbiosis and for a stable modification of mechanisms responsible for SCFAs production, and that this dysfunctional community is inherited in the passage from childhood to adulthood. These findings might open the way to novel interventions of butyric acid-like compounds as well as faecal transplant.

Complementary and Integrative Medicine and Eating Disorders in Youth: Traditional Yoga, Virtual Reality, Light Therapy, Neurofeedback, Acupuncture, Energy Psychology Techniques, Art Therapies, and Spirituality

Eating disorders (EDs) are a non-heterogeneous group of illnesses with significant physical and mental comorbidity and mortality associated with maladaptive coping. With the exception of lisdexamfetamine (Vyvanse) for binge eating disorder, no medications have been effective for the core symptoms of ED. ED requires a multimodal approach. Complementary and integrative medicine (CIM) can be helpful as an adjunct. The most promising CIM interventions are traditional yoga, virtual reality, eye movement desensitization and reprocessing, Music Therapy, and biofeedback/neurofeedback.

Novel ketamine and zinc treatment for anorexia nervosa and the potential beneficial interactions with the gut microbiome

Anorexia nervosa (AN) is a severe illness with diverse aetiological and maintaining contributors including neurobiological, metabolic, psychological, and social determining factors. In addition to nutritional recovery, multiple psychological and pharmacological therapies and brain-based stimulations have been explored; however, existing treatments have limited efficacy. This paper outlines a neurobiological model of glutamatergic and γ-aminobutyric acid (GABA)-ergic dysfunction, exacerbated by chronic gut microbiome dysbiosis and zinc depletion at a brain and gut level. The gut microbiome is established early in development, and early exposure to stress and adversity contribute to gut microbial disturbance in AN, early dysregulation to glutamatergic and GABAergic networks, interoceptive impairment, and inhibited caloric harvest from food (e.g., zinc malabsorption, competition for zinc ions between gut bacteria and host). Zinc is a key part of glutamatergic and GABAergic networks, and also affects leptin and gut microbial function; systems dysregulated in AN. Low doses of ketamine in conjunction with zinc, could provide an efficacious combination to act on NMDA receptors and normalise glutamatergic, GABAergic and gut function in AN.

Risk factors for eating disorders: findings from a rapid review

BACKGROUND

Risk factors represent a range of complex variables associated with the onset, development, and course of eating disorders. Understanding these risk factors is vital for the refinement of aetiological models, which may inform the development of targeted, evidence-based prevention, early intervention, and treatment programs. This Rapid Review aimed to identify and summarise research studies conducted within the last 12 years, focusing on risk factors associated with eating disorders.

METHODS

The current review forms part of a series of Rapid Reviews to be published in a special issue in the Journal of Eating Disorders, funded by the Australian Government to inform the development of the National Eating Disorder Research and Translation Strategy 2021-2031. Three databases were searched for studies published between 2009 and 2021, published in English, and comprising high-level evidence studies (meta-analyses, systematic reviews, moderately sized randomised controlled studies, moderately sized controlled-cohort studies, or population studies). Data pertaining to risk factors for eating disorders were synthesised and outlined in the current paper.

RESULTS

A total of 284 studies were included. The findings were divided into nine main categories: (1) genetics, (2) gastrointestinal microbiota and autoimmune reactions, (3) childhood and early adolescent exposures, (4) personality traits and comorbid mental health conditions, (5) gender, (6) socio-economic status, (7) ethnic minority, (8) body image and social influence, and (9) elite sports. A substantial amount of research exists supporting the role of inherited genetic risk in the development of eating disorders, with biological risk factors, such as the role of gut microbiota in dysregulation of appetite, an area of emerging evidence. Abuse, trauma and childhood obesity are strongly linked to eating disorders, however less conclusive evidence exists regarding developmental factors such as role of in-utero exposure to hormones. Comorbidities between eating disorders and mental health disorders, including personality and mood disorders, have been found to increase the severity of eating disorder symptomatology. Higher education attainment, body image-related factors, and use of appearance-focused social media are also associated with increased risk of eating disorder symptoms.

CONCLUSION

Eating disorders are associated with multiple risk factors. An extensive amount of research has been conducted in the field; however, further studies are required to assess the causal nature of the risk factors identified in the current review. This will assist in understanding the sequelae of eating disorder development and in turn allow for enhancement of existing interventions and ultimately improved outcomes for individuals.

The different trends in the burden of neurological and mental disorders following dietary transition in China, the USA, and the world: An extension analysis for the Global Burden of Disease Study 2019

Introduction

The highly processed western diet is substituting the low-processed traditional diet in the last decades globally. Increasing research found that a diet with poor quality such as western diet disrupts gut microbiota and increases the susceptibility to various neurological and mental disorders, while a balanced diet regulates gut microbiota and prevents and alleviates the neurological and mental disorders. Yet, there is limited research on the association between the disease burden expanding of neurological and mental disorders with a dietary transition.

Methods

We compared the disability-adjusted life-years (DALYs) trend by age for neurological and mental disorders in China, in the United States of America (USA), and across the world from 1990 to 2019, evaluated the dietary transition in the past 60 years, and analyzed the association between the burden trend of the two disorders with the changes in diet composition and food production.

Results

We identified an age-related upward pattern in disease burden in China. Compared with the USA and the world, the Chinese neurological and mental disorders DALY percent was least in the generation over 75 but rapidly increased in younger generations and surpassed the USA and/or the world in the last decades. The age-related upward pattern in Chinese disease burdens had not only shown in the presence of cardiovascular diseases, neoplasms, and diabetes mellitus but also appeared in the presence of depressive disorders, Parkinson's disease, Alzheimer's disease and other dementias, schizophrenia, headache disorders, anxiety disorders, conduct disorders, autism spectrum disorders, and eating disorders, successively. Additionally, the upward trend was associated with the dramatic dietary transition including a reduction in dietary quality and food production sustainability, during which the younger generation is more affected than the older. Following the increase in total calorie intake, alcohol intake, ratios of animal to vegetal foods, and poultry meat to pulses, the burdens of the above diseases continuously rose. Then, following the rise of the ratios of meat to pulses, eggs to pulses, and pork to pulses, the usage of fertilizers, the farming density of pigs, and the burdens of the above disease except diabetes mellitus were also ever-increasing. Even the usage of pesticides was positively correlated with the burdens of Parkinson's disease, schizophrenia, cardiovascular diseases, and neoplasms. Contrary to China, the corresponding burdens of the USA trended to reduce with the improvements in diet quality and food production sustainability.

Discussion

Our results suggest that improving diet quality and food production sustainability might be a promising way to stop the expanding burdens of neurological and mental disorders.

Association of gut-specific non-inflammatory T lymphocytes with chronic anorexia nervosa and constitutional thinness

OBJECTIVE

Previous studies of AN showed low-grade inflammation. Are low-grade inflammation and circulating lymphocytes associated with chronic conditions?

METHOD

Peripheric blood cytokines were measured using Luminex™ technology in a chronic AN cohort (mean = 67.42 months), compared to Constitutional Thinness (CT), Constitutional Obesity (CO), and Healthy Controls (HC). Secondarily a prospective cohort of chronic AN (mean = 54.11 months) was recruited to compare the functional lymphocyte profile in blood by flow cytometry to CT and HC.

RESULTS

In the AN group, most cytokine concentrations were lower than in CT and HC groups. The IL-23 (98.02 pg/ml) was elevated related to HC and CO, and the IL-10 (4.178 pg/ml) was elevated versus CO. In the CT group, IL-9 (0.06216 pg/ml) was elevated compared to AN. The AN group had high Treg (9.259% of CD4⁺ ) and CD8⁺ Integrinβ7⁺ (9.552% of CD3⁺ ) versus HC for lymphocyte populations. In CT group, elevated Treg (9.7% of CD4⁺ ) elevated percentage of CD4⁺ CCR9⁺ (5.867% of CD3⁺ ) and CD8⁺ Integrinβ7⁺ (10.21% of CD3⁺ ) were found versus HC.

CONCLUSIONS

The chronic state of AN and CT is surprisingly non-inflammatory with elevated Treg cells. These results suggest that maintaining a dysregulated response to intestinal antigens may contribute to maintaining AN.

Is fecal microbiota transplantation a useful therapeutic intervention for psychiatric disorders? A narrative review of clinical and preclinical evidence

The therapeutic management of psychiatric disorders is currently confronted with a critical need to find new therapeutic interventions due to the high rates of non-responsivity or low responsivity in the key pathologies, e.g. schizophrenia spectrum disorders, alcohol use disorders, or major depressive disorder. The modulation of intestinal microbiota has been explored in various organic and psychiatric dysfunctions, with different degrees of success. However, this type of intervention may represent a helpful add-on at a conceptual level since it does not associate negative pharmacokinetics interactions, significant adverse events, or risk for non-adherence in the long term. Oral administration of pre-, pro-, or synbiotics, and especially the treatment with fecal microbiota transplantation (FMT), are methods still in their early research phase for patients with psychiatric disorders, therefore an exploration of data regarding the potential benefits and adverse events of FMT was considered necessary. In order to accomplish this purpose, the available results of research dedicated to each category of psychiatric disorders, starting with depressive and anxiety disorders, continuing with schizophrenia, substance use disorders, and finishing with disorders diagnosed during childhood, were presented in this paper. Seven clinical trials, 16 preclinical studies, three meta-analyses/systematic reviews, and six case reports, all of these representing ten distinct categories of psychiatric disorders or manifestations, have been reviewed. Mood disorders, anxiety disorders, and alcohol dependence have been the most extensively investigated clinical entities from the FMT efficacy and tolerability perspective, and reviewed data are generally promising. Based on the current status of research, FMT may be considered a helpful intervention in specific psychiatric pathologies. Still, this review showed that most of the information is derived from entirely preclinical studies. Therefore, clinical trials with sound methodology and more participants are needed to clarify FMT's benefits and risks in psychiatric disorders.

Brain and gut microbiota disorders in the psychopathology of anorexia nervosa

Studies of pathophysiological mechanisms involved in eating disorders (EDs) have intensified over the past several years, revealing their unprecedented and unanticipated complexity. Results from many articles highlight critical aspects in each member of ED family. Notably, anorexia nervosa (AN) is a disorder due to undefined etiology, frequently associated with symptoms of depression, anxiety, obsessive-compulsiveness, accompanied by endocrine alterations, altered immune response, increased inflammation, and dysbiosis of the gut microbiota. Hence, an advanced knowledge of how and why a multisystem involvement exists is of paramount importance to understand the pathogenetic mechanisms of AN. In this review, we describe the change in the brain structure/function focusing on hypothalamic endocrine disorders and the disequilibrium of gut microbiota in AN that might be responsible for the psychopathological complication.

A critical analysis of eating disorders and the gut microbiome

The gut microbiota, also known as our "second brain" is an exciting frontier of research across a multitude of health domains. Gut microbes have been implicated in feeding behaviour and obesity, as well as mental health disorders including anxiety and depression, however their role in the development and maintenance of eating disorders (EDs) has only recently been considered. EDs are complex mental health conditions, shaped by a complicated interplay of factors. Perhaps due to an incomplete understanding of the etiology of EDs, treatment remains inadequate with affected individuals likely to face many relapses. The gut microbiota may be a missing piece in understanding the etiology of eating disorders, however more robust scientific inquiry is needed in the field before concrete conclusions can be made. In this spotlight paper, we critically evaluate what is known about the bi-directional relationship between gut microbes and biological processes that are implicated in the development and maintenance of EDs, including physiological functioning, hormones, neurotransmitters, the central nervous system, and the immune system. We outline limitations of current research, propose concrete steps to move the field forward and, hypothesize potential clinical implications of this research. Our gut is inhabited by millions of bacteria which have more recently been referred to as "our second brain". In fact, these microbes are thought to play a role in ED behaviour, associated anxiety and depression, and even affect our weight. Recent research has dove into this field with promising findings that have the potential to be applied clinically to improve ED recovery. The present paper discusses what is known about the gut microbiome in relation to EDs and the promising implications that leveraging this knowledge, through fecal microbiome transplants, probiotics, and microbiome-directed supplemental foods, could have on ED treatment.

Sensor Technology and Intelligent Systems in Anorexia Nervosa: Providing Smarter Healthcare Delivery Systems

Ubiquitous technology, big data, more efficient electronic health records, and predictive analytics are now at the core of smart healthcare systems supported by artificial intelligence. In the present narrative review, we focus on sensing technologies for the healthcare of Anorexia Nervosa (AN). We employed a framework inspired by the Interpersonal Neurobiology Theory (IPNB), which posits that human experience is characterized by a flow of energy and information both within us (within our whole body), and between us (in the connections we have with others and with nature). In line with this framework, we focused on sensors designed to evaluate bodily processes (body sensors such as implantable sensors, epidermal sensors, and wearable and portable sensors), human social interaction (sociometric sensors), and the physical environment (indoor and outdoor ambient sensors). There is a myriad of man-made sensors as well as nature-based sensors such as plants that can be used to design and deploy intelligent systems for human monitoring and healthcare. In conclusion, sensing technologies and intelligent systems can be employed for smarter healthcare of AN and help to relieve the burden of health professionals. However, there are technical, ethical, and environmental sustainability issues that must be considered prior to implementing these systems. A joint collaboration of professionals and other members of the society involved in the healthcare of individuals with AN can help in the development of these systems. The evolution of cyberphysical systems should also be considered in these collaborations.

Anorexia nervosa and autoimmune comorbidities: A bidirectional route?

Immunological dysfunctions in eating disorders have recently gained increasing scientific attention. Furthermore, the reciprocal association between anorexia and autoimmune diseases is of particular interest and suggests a role of autoimmunity in the pathogenesis of eating disorders. Anorexia nervosa (AN) and autoimmune diseases are linked by a bidirectional relationship based on common immunopathological mechanisms. In this review, in addition to reporting the numerous cases described in which autoimmune disorders are associated with anorexia or vice versa, we summarize the many aspects of this relationship between the immune system (IS) and AN. We describe how the microbiota affects the IS, disrupts gut-brain communication, and possibly triggers eating disorders. We also describe the shared immunological pathways of autoimmune and eating disorders and in particular the occurrence of disrupted T cell tolerance and autoantibodies in AN. The described observations represent the starting point for possible, future research directions.

Expression of salivary immunoglobulins and their association with analgesic neuropeptide opiorphin in anorexia nervosa during adolescence

BACKGROUND

Patients who suffer from anorexia nervosa (AN) are characterized by exceedingly lower body weight, micro- and macro-nutrient deficiencies, and hyposalivation as compared to healthy subjects. In addition, AN may predispose to difficulties in oral health maintenance. However, little is known about the relationship between stress-dependent salivary neuro/immunopeptidergic biomarkers such as opiorphin and immunoglobulins (Ig) and AN.The aim of this case-control study was to evaluate salivary opiorphin and immunoglobulins in female children and adolescents diagnosed with AN compared to healthy controls.

METHODS

Adolescent patients with clinically-confirmed severe restrictive subtype AN (Body Mass Index BMI < 15 kg/m², mean age 15.0 ± 1.8, n = 83) were examined in the first week of hospital admission and compared to healthy matched controls (n = 79). Measurements of salivary opiorphin, IgA, IgG, IgM (ELISA technique), and oral hygiene levels (Plaque Control Record index-PCR) were performed.

RESULTS

In the AN group, a significantly higher concentration of opiorphin was evidenced (3.1 ± 4.1 ng/ml) compared to the control group (1.1 ± 1.2 ng/ml), (p < 0.001), contrary to IgM, which was significantly lower (311.0 ± 185.3 ng/ml) than in the control group (421.2 ± 168.1 ng/ml), (p < 0.001). There were no significant differences in the levels of IgA and IgG, despite a higher concentration of IgA in the AN group vs. controls (p = 0.14). Spearman analysis revealed a correlation between opiorphin and age (p < 0.05), but also with all immunoglobulins IgA, IgG, IgM (p = 0.006, p < 0.001, p < 0.001). Similarly a correlation was found between PCR index and immunoglobulins IgG, IgM (respectively p = 0.028, p < 0.001), and between body mass, BMI, IBW% and IgA, IgM (all p < 0.05).

CONCLUSIONS

In the acute phase of AN, salivary changes in opiorphin and immunoglobulins related to dental plaque suggest an essential role in oral health balance. Changes related to AN may affect the anti-inflammatory and analgesic components of saliva and suggest their use as neurobiological markers in severe malnutrition.

Disordered eating as a repercussion of sexual assault: a consequence to consider

PURPOSE

This study aims at clarifying the links between sexual violence and disordered eating (DE).

METHODS

In a sample of 12,638 victims of self-reported sexual violence, we analyzed the situation of 546 victims that declared having developed DE. We assessed the characteristics of the assault (age, type of aggression) and the medical consequences (PTSD, depression, suicide attempts, anxiety disorders, etc.).

RESULTS

DE prevalence was 4.3% in the victim sample. The age of the first assault in DE victims was significantly lower than that of the whole population (12 years vs 16 years for median; p < 0.001). A much higher prevalence of sexual assault consequences was present in victims developing DE with odd ratios (OR) for: self-mutilation (OR = 11.5 [8.29-15.95], p < 0.001); depression (OR = 5.7 [4.81-6.86], p < 0.001); self-medication (OR = 5.3 [3.86-7.19], p < 0.001); suicide attempts (OR = 4.5 [3.59-5.67], p < 0.001); post-traumatic stress disorder (OR = 3.8 [2.99-4.78], p < 0.001); anxiety troubles (OR = 5.2 [4.11-6.47], p < 0.001); alcoholism (OR = 4.0 [2.81-5.58], p < 0.001).

CONCLUSION

This study confirms the link between DE and sexual violence, especially in childhood, leading to severe psychological consequences. In this context, DE should be envisaged as a coping strategy accompanying emotional dysregulation due to traumatic events, and be treated as such.

LEVEL OF EVIDENCE

Level IV: Evidence obtained from multiple time series analysis such as case studies.

Interactions between emotions and eating behaviors: Main issues, neuroimaging contributions, and innovative preventive or corrective strategies

Emotional eating is commonly defined as the tendency to (over)eat in response to emotion. Insofar as it involves the (over)consumption of high-calorie palatable foods, emotional eating is a maladaptive behavior that can lead to eating disorders, and ultimately to metabolic disorders and obesity. Emotional eating is associated with eating disorder subtypes and with abnormalities in emotion processing at a behavioral level. However, not enough is known about the neural pathways involved in both emotion processing and food intake. In this review, we provide an overview of recent neuroimaging studies, highlighting the brain correlates between emotions and eating behavior that may be involved in emotional eating. Interaction between neural and neuro-endocrine pathways (HPA axis) may be involved. In addition to behavioral interventions, there is a need for a holistic approach encompassing both neural and physiological levels to prevent emotional eating. Based on recent imaging, this review indicates that more attention should be paid to prefrontal areas, the insular and orbitofrontal cortices, and reward pathways, in addition to regions that play a major role in both the cognitive control of emotions and eating behavior. Identifying these brain regions could allow for neuromodulation interventions, including neurofeedback training, which deserves further investigation.

Alterations of the gut microbiota in borderline personality disorder

OBJECTIVE

A growing body of research has shown that people with a wide range of psychiatric disorders, including depression, present with alterations of the gut microbiota, although it is unclear if differences may be caused by the action of psychotropic medication. No data exist for patients with borderline personality disorder (BPD), a psychiatric condition that is frequently comorbidly associated with depression.

METHODS

Twenty-four unmedicated patients and twenty-one age- and sex-matched healthy controls were recruited. Stool samples were frozen at -80 °C within ten minutes after defecation. The V4 region of bacterial 16S ribosomal RNA (rRNA) gene was sequenced on an Illumina platform. Operational taxonomic units (OTUs) were used for further analysis of community structure, alpha- and beta-diversity.

RESULTS

There was no significant difference in alpha- and beta-diversity between patients and controls. However, the Bacteroidetes/Firmicutes-ratio was higher in patients, approaching significance (p = 0.06, r = 0.23). Four species were significantly less abundant in BPD patients, namely Pseudoflavonifractor phocaensis (p = 0.003, r = 0.41), Eubacterium coprostanoligenes (p = 0.01, r = 0.34), Anaerotaenia torta (p = 0.01, r = 0.35), and (statistically somewhat weaker) Parabacteroides chongii (p = 0.046, r = 0.26), which correlated with various psychometric scores.

CONCLUSION

Differences in the taxonomic composition may indicate a potential dysbiosis among SCFA-producing bacteria in BPD. Future research is warranted to replicate these findings in independent and larger samples. If confirmed, the results suggest that microbiota-targeted therapies may be a useful adjunct strategy for BPD.

Intestinal permeability and appetite regulating peptides-reactive immunoglobulins in severely malnourished women with anorexia nervosa

BACKGROUND & AIMS

In the last decades, the role of microbiota-gut-brain axis has emerged in the regulation of eating behavior and in the pathophysiology of anorexia nervosa (AN) that remains poorly understood. Particularly, a gut-derived dysregulation of immune response has been proposed leading to immunoglobulins directed against appetite-regulating peptides. However, intestinal permeability in patients with anorexia nervosa has been poorly documented.

METHODS

In the present prospective case-control study, we thus compared intestinal permeability, appetite-regulating peptides and their reactive immunoglobulins measured in severely malnourished women with AN (n = 17; 28 [21-35] y; 14.9 [14.1-15.2] kg/m²) to healthy volunteers (HV, n = 34; 26 [23-35] y; 22.3 [20.6-23.6] kg/m²).

RESULTS

Patients with AN exhibited an increased urinary lactulose/mannitol ratio, both in 0-5 h (0.033 [0.013-0.116]) and 5-24 h samples (0.115 [0.029-0.582]), when compared to HV (0.02 [0.008-0.045], p = 0.0074 and 0.083 [0.019-0.290], p = 0.0174, respectively), suggesting an increased intestinal permeability. Urinary excretion of sucralose and plasma zonulin were not different. The levels of plasma total ghrelin and desacyl-ghrelin were increased in patients with AN compared to HV, whereas plasma leptin concentration was decreased. In addition, αMSH remained unchanged compared to HV. Finally, we did not observe any modification of the levels of total or free αMSH, leptin or ghrelin-reactive immunoglobulin G and M, as well as for their affinity properties. Only, a weak decrease of the dissociation constant (kd) for acyl-ghrelin-reactive IgG was observed in patients with AN (p = 0.0411).

CONCLUSIONS

In conclusion, severely malnourished patients with AN show a higher intestinal permeability than HV without evidence of an effect on appetite regulating peptides-reactive immunoglobulins.

Effects of Glycyrrhiza Polysaccharides on Chickens' Intestinal Health and Homeostasis

The overuse of antibiotics in poultry farming causes the accumulation of drug residue in animals' bodies and the occurrence of antibiotic-resistant bacteria, which not only compromise animals' health but ultimately endanger human health. Thus, there is an urgent need for a novel poultry feed additive to substitute for excessive antibiotics. Glycyrrhiza polysaccharides (GPS) derived from Chinese licorice have shown promising immunomodulatory effects in previous studies. The present study investigated the pharmacological effects of GPS on poultry intestines to assess whether it can be used as a feed additive. The results show that GPS can increase production of sIgA, promote the secretion activity of goblet cells, alter the gut microbial composition and lead to changes in short-chain fatty acids. GPS also elevated both Th1 and Th2 immune responses by facilitating the expression of IL-2, IL-4, IL-1β, and IFN-γ while increasing the proportion of both CD4+ and CD8+ cells in the intestine. Moreover, the results of 16S rRNA gene sequencing showed that GPS could significantly change intestinal microbiota composition in the intestine, evidenced by the increased proportion of Bacteroides, Butyricicoccus and Eisenbergiella, as well as a decreased portion of Erysipelatoclostridium, leading to a healthier intestinal microbiota composition for the host. Taken together, it can be concluded that GPS is safe to use as a novel feed additive that can be used as an alternative to prophylactic antibiotics in poultry feeding.

Cultural shifts in the symptoms of Anorexia Nervosa: The case of Orthorexia Nervosa

Orthorexia Nervosa (ON) is a term describing a fixation on food purity, involving ritualized eating patterns and a rigid avoidance of "unhealthy foods." Those self-identified as having ON tend to focus on food composition and feel immense guilt after eating food deemed "unhealthy." Although not formally recognized as a psychiatric disorder by the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), ON has received increasing attention since its identification in 1997. There is ongoing work to establish diagnostic and empirical tools for measuring ON; embedded in this is the question as to whether or not ON is a new eating disorder. In this paper, we argue ON is not a new psychiatric disorder but rather a new cultural manifestation of anorexia nervosa (AN). We begin by providing an overview of historical representations and classification of eating disorders, with a specific focus on AN. This is followed by discussion of the rise in diet culture and healthism since the 19th century. We conclude by examining the diagnostic validity and utility of ON through a discussion of empirical evidence. Classifying ON under the diagnostic umbrella of AN may improve our understanding of factors underlying restrictive eating behaviors.

Obesity and Eating Disorders in Children and Adolescents: The Bidirectional Link

Obesity, eating disorders and unhealthy dieting practices among children and adolescents are alarming health concerns due to their high prevalence and adverse effects on physical and psychosocial health. We present the evidence that eating disorders and obesity can be managed or prevented using the same interventions in the pediatric age. In the presence of obesity in the pediatric age, disordered eating behaviors are highly prevalent, increasing the risk of developing eating disorders. The most frequently observed in subjects with obesity are bulimia nervosa and binge-eating disorders, both of which are characterized by abnormal eating or weight-control behaviors. Various are the mechanisms overlying the interaction including environmental and individual ones, and different are the approaches to reduce the consequences. Evidence-based treatments for obesity and eating disorders in childhood include as first line approaches weight loss with nutritional management and lifestyle modification via behavioral psychotherapy, as well as treatment of psychiatric comorbidities if those are not a consequence of the eating disorder. Drugs and bariatric surgery need to be used in extreme cases. Future research is necessary for early detection of risk factors for prevention, more precise elucidation of the mechanisms that underpin these problems and, finally, in the cases requiring therapeutic intervention, to provide tailored and timely treatment. Collective efforts between the fields are crucial for reducing the factors of health disparity and improving public health.

Overtraining Syndrome (OTS) and Relative Energy Deficiency in Sport (RED-S): Shared Pathways, Symptoms and Complexities

The symptom similarities between training-overload (with or without an Overtraining Syndrome (OTS) diagnosis) and Relative Energy Deficiency in Sport (RED-S) are significant, with both initiating from a hypothalamic-pituitary origin, that can be influenced by low carbohydrate (CHO) and energy availability (EA). In this narrative review we wish to showcase that many of the negative outcomes of training-overload (with, or without an OTS diagnosis) may be primarily due to misdiagnosed under-fueling, or RED-S, via low EA and/or low CHO availability. Accordingly, we undertook an analysis of training-overload/OTS type studies that have also collected and analyzed for energy intake (EI), CHO, exercise energy expenditure (EEE) and/or EA. Eighteen of the 21 studies (86%) that met our criteria showed indications of an EA decrease or difference between two cohorts within a given study (n = 14 studies) or CHO availability decrease (n = 4 studies) during the training-overload/OTS period, resulting in both training-overload/OTS and RED-S symptom outcomes compared to control conditions. Furthermore, we demonstrate significantly similar symptom overlaps across much of the OTS (n = 57 studies) and RED-S/Female Athlete Triad (n = 88 studies) literature. It is important to note that the prevention of under-recovery is multi-factorial, but many aspects are based around EA and CHO availability. Herein we have demonstrated that OTS and RED-S have many shared pathways, symptoms, and diagnostic complexities. Substantial attention is required to increase the knowledge and awareness of RED-S, and to enhance the diagnostic accuracy of both OTS and RED-S, to allow clinicians to more accurately exclude LEA/RED-S from OTS diagnoses.

The Probiotic Strain H. alvei HA4597® Improves Weight Loss in Overweight Subjects under Moderate Hypocaloric Diet: A Proof-of-Concept, Multicenter Randomized, Double-Blind Placebo-Controlled Study

Background: Increasing evidence supports the role of the gut microbiota in the control of body weight and feeding behavior. Moreover, recent studies have reported that the probiotic strain Hafnia alvei HA4597^® (HA), which produces the satietogenic peptide ClpB mimicking the effect of alpha-MSH, reduced weight gain and adiposity in rodent models of obesity. Methods: To investigate the clinical efficacy of HA, 236 overweight subjects were included, after written informed consent, in a 12-week prospective, double-blind, randomized study. All subjects received standardized counselling for a −20% hypocaloric diet and were asked to maintain their usual physical activity. Subjects of the HA group received two capsules per day providing 100 billion bacteria per day and subjects in the Placebo (P) group received two placebo capsules. The primary endpoint was the percentage of subjects achieving a weight loss of at least 3% after 12 weeks. Intention-to-treat statistical analysis was performed using exact-Fischer, Mann-Whitney and paired-Wilcoxon tests as appropriate. Results: In the HA group, significantly more subjects (+33%) met the primary endpoint than in the P group (54.9 vs. 41.4%, p = 0.048). In the HA group, an increased feeling of fullness (p = 0.009) and a greater loss of hip circumference (p < 0.001) at 12 weeks were also observed. Fasting glycemia at 12 weeks was significantly lower (p < 0.05) in the HA compared to P group. Clinical and biological tolerance was good in both groups. Conclusions: A 12-week treatment with the probiotic strain H. alvei HA4597^® significantly improves weight loss, feeling of fullness and reduction of hip circumference in overweight subjects following moderate hypocaloric diet. These data support the use of H. alvei HA4597^® in the global management of excess weight.

Peripheral Vascular Abnormalities in Anorexia Nervosa: A Psycho-Neuro-Immune-Metabolic Connection

Immune, neuroendocrine, and autonomic nervous system dysregulation in anorexia nervosa lead to cardiovascular complications that can potentially result in increased morbidity and mortality. It is suggested that a complex non-invasive assessment of cardiovascular autonomic regulation-cardiac vagal control, sympathetic vascular activity, and cardiovascular reflex control-could represent a promising tool for early diagnosis, personalized therapy, and monitoring of therapeutic interventions in anorexia nervosa particularly at a vulnerable adolescent age. In this view, we recommend to consider in the diagnostic route, at least in the subset of patients with peripheral microvascular symptoms, a nailfold video-capillaroscopy as an easy not invasive tool for the early assessing of possible cardiovascular involvement.