Aetiopathogenesis and pathophysiology of bulimia nervosa: biological bases and implications for treatment

Effects of Microbiota Imbalance in Anxiety and Eating Disorders: Probiotics as Novel Therapeutic Approaches

Anxiety and eating disorders produce a physiological imbalance that triggers alterations in the abundance and composition of gut microbiota. Moreover, the gut–brain axis can be altered by several factors such as diet, lifestyle, infections, and antibiotic treatment. Diet alterations generate gut dysbiosis, which affects immune system responses, inflammation mechanisms, the intestinal permeability, as well as the production of short chain fatty acids and neurotransmitters by gut microbiota, which are essential to the correct function of neurological processes. Recent studies indicated that patients with generalized anxiety or eating disorders (anorexia nervosa, bulimia nervosa, and binge-eating disorders) show a specific profile of gut microbiota, and this imbalance can be partially restored after a single or multi-strain probiotic supplementation. Following the PRISMA methodology, the current review addresses the main microbial signatures observed in patients with generalized anxiety and/or eating disorders as well as the importance of probiotics as a preventive or a therapeutic tool in these pathologies.

Treatment interventions for Severe and Enduring Eating Disorders: Systematic review

OBJECTIVE

Approximately 20% of people with Anorexia Nervosa (AN) and 10% with Bulimia Nervosa (BN) will eventually develop a long-standing illness. Although there is no set definition for Severe and Enduring eating Disorder (SE-ED), the common criteria relate to a long duration of the disorder and a number of unsuccessful treatment attempts. Research evidence for treatment of SE-ED remains limited, thus the objective of this systematic review was to describe different treatment interventions and their effects on SE-ED-related outcomes.

METHOD

A systematic search for quantitative treatment studies of adult participants with SE-ED was conducted in June 2019 (PROSPERO, CRD42018115802) with no restriction on eating disorder type. Altogether, 2,938 studies were included for title and abstract screening.

RESULTS

After systematic searches and article screening, 23 studies (3 randomized controlled trials, 3 open-label studies, 8 naturalistic follow-up studies, 8 case series and case studies, and 1 partially blinded pilot study) were included in the analysis and data extraction. Methodological quality of the included studies was generally low. Inpatient treatment programs (n = 5) were effective in short-term symptom reduction, but long-term results were inconsistent. Outpatient and day-hospital treatment programs (n = 5) seemed promising for symptom reduction. Drug interventions (n = 5) showed some benefits, especially as adjuvant therapies. Brain stimulation (n = 6) led to improvements in depressive symptoms. Other treatments (n = 2) produced mixed results.

DISCUSSION

This is the first systematic review to examine all of the different treatment interventions that have been studied in SE-ED. The results will inform future interventions in research and clinical practice.

Anorexia nervosa: Gut microbiota-immune-brain interactions

Anorexia nervosa is a psychiatric disorder defined by an extremely low body weight, a devastating fear of weight gain, and body image disturbance, however the etiopathogenesis remains unclear. The objective of the article is to provide a comprehensive review on the potential role of gut microbiota in pathogenesis of anorexia nervosa. Recent advances in sequencing techniques used for microbial detection revealed that this disease is associated with disruption of the composition of normal gut microbiota (dysbiosis), manifested by low microbial diversity and taxonomic differences as compared to healthy individuals. Microorganisms present in the gut represent a part of the so called "microbiota-gut-brain" axis that affect the central nervous system and thus human behavior via the production of various neuroactive compounds. In addition, cells of the immune system are equipped with receptors for these neuroactive substances. Microbiota of the intestinal system also represent a very important antigenic source. These antigens can mimic some host neuropeptides and neurohormones and thus trigger the production of autoantibodies which cross-react with these compounds. The levels and affinities of these antibodies are thought to be associated with neuropsychiatric conditions including anxiety, depression, and eating and sleep disorders. The study of microbiota function in diseases could bring new insights to the pathogenetic mechanisms.

Pharmacological manipulations in animal models of anorexia and binge eating in relation to humans

Eating disorders, such as anorexia nervosa (AN), bulimia nervosa (BN) and binge eating disorders (BED), are described as abnormal eating habits that usually involve insufficient or excessive food intake. Animal models have been developed that provide insight into certain aspects of eating disorders. Several drugs have been found efficacious in these animal models and some of them have eventually proven useful in the treatment of eating disorders. This review will cover the role of monoaminergic neurotransmitters in eating disorders and their pharmacological manipulations in animal models and humans. Dopamine, 5-HT (serotonin) and noradrenaline in hypothalamic and striatal regions regulate food intake by affecting hunger and satiety and by affecting rewarding and motivational aspects of feeding. Reduced neurotransmission by dopamine, 5-HT and noradrenaline and compensatory changes, at least in dopamine D2 and 5-HT(2C/2A) receptors, have been related to the pathophysiology of AN in humans and animal models. Also, in disorders and animal models of BN and BED, monoaminergic neurotransmission is down-regulated but receptor level changes are different from those seen in AN. A hypofunctional dopamine system or overactive α2-adrenoceptors may contribute to an attenuated response to (palatable) food and result in hedonic binge eating. Evidence for the efficacy of monoaminergic treatments for AN is limited, while more support exists for the treatment of BN or BED with monoaminergic drugs.

The pharmacological options in the treatment of eating disorders

The eating disorders (DCA) are complex systemic diseases with high social impact, which tend to become chronic with significant medical and psychiatric comorbidities. The literature data showed that there is good evidence to suggest the use of SSRIs, particularly at high doses of fluoxetine, in the treatment of BN reducing both the crisis of binge that the phenomena compensates and reducing the episodes of binge in patients with BED in the short term. Also, the topiramate (an AED) showed a good effectiveness in reducing the frequency and magnitude of episodes of binge with body weight reduction, both in the BN that is in the therapy of BED. To date, modest data support the use of low doses of second-generation antipsychotics in an attempt to reduce the creation of polarized weight and body shapes, the obsessive component, and anxiety in patients with AN. Data in the literature on long-term drug treatment of eating disorders are still very modest. It is essential to remember that the pharmacotherapy has, however, a remarkable efficacy in treating psychiatric disorders that occur in comorbidity with eating disorders, such as mood disorders, anxiety, insomnia, and obsessive-compulsive personality disorders and behavior.

The role of "mixed" orexigenic and anorexigenic signals and autoantibodies reacting with appetite-regulating neuropeptides and peptides of the adipose tissue-gut-brain axis: relevance to food intake and nutritional status in patients with anorexia nervosa and bulimia nervosa

Eating disorders such as anorexia (AN) and bulimia nervosa (BN) are characterized by abnormal eating behavior. The essential aspect of AN is that the individual refuses to maintain a minimal normal body weight. The main features of BN are binge eating and inappropriate compensatory methods to prevent weight gain. The gut-brain-adipose tissue (AT) peptides and neutralizing autoantibodies play an important role in the regulation of eating behavior and growth hormone release. The mechanisms for controlling food intake involve an interplay between gut, brain, and AT. Parasympathetic, sympathetic, and serotoninergic systems are required for communication between brain satiety centre, gut, and AT. These neuronal circuits include neuropeptides ghrelin, neuropeptide Y (NPY), peptide YY (PYY), cholecystokinin (CCK), leptin, putative anorexigen obestatin, monoamines dopamine, norepinephrine (NE), serotonin, and neutralizing autoantibodies. This extensive and detailed report reviews data that demonstrate that hunger-satiety signals play an important role in the pathogenesis of eating disorders. Neuroendocrine dysregulations of the AT-gut-brain axis peptides and neutralizing autoantibodies may result in AN and BN. The circulating autoantibodies can be purified and used as pharmacological tools in AN and BN. Further research is required to investigate the orexigenic/anorexigenic synthetic analogs and monoclonal antibodies for potential treatment of eating disorders in clinical practice.

Neurobiological and psychopathological variables related to emotional instability: a study of their capability to discriminate patients with bulimia nervosa from healthy controls

OBJECTIVE

To analyze the capability of a set of neurobiological and psychopathological variables to discriminate bulimia nervosa (BN) patients from healthy controls.

METHOD

Seventy-five female patients with purging BN and 30 healthy controls were compared for psychopathology (impulsivity, borderline personality traits, depressive symptoms and self-defeating personality traits) and neurobiological parameters reflecting hypothalamic-pituitary-adrenal axis activity (morning serum cortisol before and after dexamethasone) and monoamine activity (24-hour urinary excretion of norepinephrine, serotonin, dopamine, and their main metabolites: 3-methoxy-4-hydroxyphenylglycol, 5-hydroxyindoleacetic acid, and homovanillic acid). Furthermore, the relationships between the 2 sets of variables were compared in the 2 samples.

RESULTS

BN patients displayed higher impulsivity, more severe depressive features, and more borderline and self-defeating personality traits than controls. The 4 psychopathological variables were strongly interrelated in patients, whereas only depressive features correlated with self-defeating personality traits in controls. Patients had lower 24-hour excretion of serotonin and dopamine than controls, as well as lower ability to suppress cortisol. The relations between the biochemical and the psychopathological variables were only significant in the BN patients, but not in the control group. When discriminant analysis methods were applied, patients and controls differed for psychopathology (impulsive behaviors and borderline personality traits) and biological parameters (baseline cortisol and dopamine excretion), but when the variables were analyzed together, the differences in neurobiological parameters appeared as mediated by the psychopathological status.

DISCUSSION

Our results suggest that hypothalamic-pituitary-adrenal axis activity, dopamine activity and other biological parameters are worthy of further study as potential dimensional markers of BN, although they seem to depend on the psychopathological status of the patients, in such a way that the psychopathological items associated with emotional instability (impulsivity and borderline personality traits) seem to be more reliable as clinical markers at the time being.

Plasma homovanillic acid in adolescents with bulimia nervosa

Dopaminergic abnormalities in bulimia nervosa have been reported in some studies, but results are not consistent across studies. In the present study, clinical characteristics, plasma level of homovanillic acid (pHVA) and two scales - the Eating Attitudes Test (EAT) and the Beck Depression Inventory (BDI) - were assessed in 36 adolescent bulimia nervosa patients (mean age16.3 years, S.D. 1.1) who were consecutively seen on an Eating Disorder Unit. Levels of pHVA were also measured in 16 healthy control adolescents from the general population. Patients had significantly higher mean pHVA than controls. Eighteen patients (50%) had a pHVA level equal to or higher than the mean of control subjects plus one standard deviation, and this group of patients had significantly higher mean BDI scores and non-significantly higher mean EAT scores, although they did not differ from the other patients in age, time elapsed since the onset of disorder, body mass index and number of binges or vomits. Moreover, in logistic regression analysis the BDI score proved to be an independent predictor of high pHVA. The level of pHVA is increased in bulimia nervosa patients with high scores on measures of depressive and eating symptomatology.

Successful treatment with duloxetine in a case of treatment refractory bulimia nervosa: a case report

The authors report a case of treatment refractory bulimia nervosa successfully treated with duloxetine, a combined serotonin and norepinephrine reuptake inhibitor, with complete remission of the patient's bingeing and purging behaviours. This case is discussed in the context of existing literature on the psychopharmacology of bulimia nervosa.

Treatment of bulimia nervosa with fluvoxamine: a randomized controlled trial

Bulimia nervosa (BN) is one of the most common eating disorders in industrialized societies. It has been suggested that reduced serotonin activity triggers some of the cognitive and mood disturbances associated with BN. For this reason, the pharmacologic treatment of BN consists mainly of selective serotonin reuptake inhibitors (SSRIs), which have been proven effective. At present, the physiologic bases of this disorder are not yet completely understood. We conducted a randomized controlled trial to verify the efficacy of the SSRI fluvoxamine in patients with a diagnosis of BN. Twelve female outpatients aged 21 to 34 years with a diagnosis of BN-binge purging (as defined by the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders [DSM IV]) were randomly assigned to 2 treatment groups: the fluvoxamine 200 mg/day group and the placebo group. The patients underwent weekly clinical assessments for 12 weeks. At the end of the observation period, there was a statistically significant reduction in the number of binge-eating crises and purging episodes in the fluvoxamine group compared with placebo. In no case was treatment interrupted because of emergent side effects. These findings support the hypothesis that fluvoxamine is well tolerated and effective in reducing binge-eating crises and purging episodes in patients with BN.

Enhanced serum cholesterol and triglyceride levels in bulimia nervosa: relationships to psychiatric comorbidity, psychopathology and hormonal variables

Increased levels of cholesterol have been reported in patients with bulimia nervosa (BN), but all but one of the published studies were performed on non-fasting subjects, which limits the interpretation of this finding. Moreover, the relationships between serum lipids and comorbid psychiatric disorders or bulimic psychopathology have scarcely been investigated. We measured serum levels of total cholesterol, triglycerides, glucose, 17beta-estradiol and thyroid hormones in 75 bulimic women and 64 age-matched healthy females after an overnight fast. Compared with healthy women, bulimic patients exhibited significantly enhanced serum levels of cholesterol and triglycerides, but similar values of glucose, 17beta-estradiol, FT3 and FT4. No significant differences emerged in these variables between patients with or without comorbid depression, borderline personality disorder or lifetime anorexia nervosa. Circulating cholesterol was positively correlated to the patients' drive for thinness, ineffectiveness, enteroceptive awareness and impulse regulation sub-item scores of the Eating Disorder Inventory-2. These findings confirm that BN is associated with increased levels of serum lipids. This alteration may be involved in the pathophysiology of certain psychopathological characteristics of BN and cannot be explained by the co-occurrence of other psychiatric disorders.

Factors related to severity of vomiting behaviors in bulimia nervosa

Assessments of the severity of vomiting (weekly frequency), depressive and eating-related psychopathology, anger level and management, and personality dimensions were used to characterize patients with bulimia nervosa binge purging type (BN-BP). The sample comprised 130 outpatients with BN and 130 control women. The Eating Disorder Inventory-2 (EDI-2), the State-Trait Anger Expression Inventory, the Beck Depression Inventory, and the Temperament and Character Inventory (TCI) were administered to all patients. The Self-Directedness dimension of the TCI and the Bulimia subscale of the EDI-2 were the strongest predictors of the severity of bulimic behavior; anger levels and anger expression were not so strongly related to illness severity. A more severe form of bulimic symptomatology probably has substrata in specific character deficits (low Self-Directedness on the TCI) and particular psychopathological features (high bulimia on the EDI-2). Patients with a high frequency of vomiting need specific therapeutic interventions to enhance the character dimension of Self-Directedness.

Use of reboxetine in bulimia nervosa: a pilot study

The pharmacological approach to bulimia nervosa is mainly based (BN) on selective serotonin reuptake inhibitors, but many elements suggest the possible involvement of the noradrenergic system in this disorder. The aim of the study was to assess the efficacy of reboxetine--a selective norepinephrine uptake inhibitor--in a sample of bulimic outpatients, after 3 months of treatment. Twenty-eight of 77 consecutively admitted patients with a DSM-IV diagnosis of BN (without Axis I comorbidity) received reboxetine. All patients were assessed at baseline (T0), and after 1 month (T1) and 3 months (T3), respectively, of treatment with reboxetine 4 mg/day. The subjects were administered the following questionnaires: Hamilton Rating Scale for Anxiety (HAM-A) and for Depression (HAM-D), Global Assessment Functioning (GAF), Eating Disorder Inventory-2 (EDI-2) and Body Shape Questionnaire (BSQ). Sixty percent of the patients were responsive to treatment(evaluated as a 50% decrease of bulimic behaviours). After 3 months of treatment, a significant reduction emerged in the scores of various EDI-2 subscales (Bulimia, Drive for Thinness, Body Dissatisfaction, Social Insecurity, Interpersonal Distrust, etc.) and in the BSQ total score. Moreover, depressive symptoms (HAM-D) and Global Functioning (GAF) scores showed a significant improvement. These data support a fast and favourable effect of reboxetine in the treatment of BN, both on symptoms and psychopathological features. Moreover, the specific and strong action of reboxetine on improvement of social functioning is also supported in this disorder.