Reduced plasma leptin concentrations in bulimia nervosa

Current Discoveries and Future Implications of Eating Disorders

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

Increased plasma asprosin levels are associated with overeating and loss of control in drug-free bulimia nervosa

PURPOSE

Abnormalities in appetite hormones have been implicated in bulimia nervosa (BN). Orexigenic hormone asprosin has been reported to be associated with food intake and weight gain, but no relevant studies have yet been reported in BN. This study investigated asprosin concentrations and their association with eating disorder symptoms in patients with BN.

METHODS

This study recruited a total of 26 BN patients and 23 healthy controls (HC). Symptom severity for eating disorders, depression, and anxiety was determined by the Eating Disorder Examination Questionnaire 6.0, Beck Depression Inventory, Version 2, and Beck Anxiety Inventory, respectively. In addition, the study employed sandwich enzyme-linked immunoassay technology to determine plasma asprosin and glucose concentrations in all participants.

RESULTS

The results revealed that plasma asprosin concentrations were significantly higher in BN patients than in HC (P = 0.037), but the difference disappeared after adjusting for the covariate BMI (F = 2.685, P = 0.108). Correlation analysis showed that asprosin concentration was positively correlated with overeating (r = 0.451, P = 0.021) and eating loss of control (r = 0.483, P = 0.012) in BN patients. Linear regression analysis indicated that an increase in asprosin concentration was associated with an increase in the times of overeating (F = 6.303, P = 0.019, R² = 0.208). Multiple linear regression showed that increases in asprosin concentration and BDI-II total score could explain the frequent eating loss of control (F = 5.766, P = 0.009, R² = 0.334).

CONCLUSIONS

The present study is the first report of plasma asprosin concentration in BN patients and found that overeating and eating loss of control increased with the increase of asprosin concentration. Additionally, asprosin level and degree of depression may explain the frequency of loss of control.

LEVEL OF EVIDENCE

Level III: Evidence obtained from case-control studies.

Risk factors for eating disorders: an umbrella review of published meta-analyses

Objective:

To grade the evidence about risk factors for eating disorders (anorexia nervosa, bulimia nervosa, and binge eating disorder) with an umbrella review approach.

Methods:

This was a systematic review of observational studies on risk factors for eating disorders published in PubMed/PsycInfo/Embase until December 11th, 2019. We recalculated random-effect meta-analyses, heterogeneity, small-study effect, excess significance bias and 95% prediction intervals, grading significant evidence (p < 0.05) from convincing to weak according to established criteria. Quality was assessed with the Assessment of Multiple Systematic Reviews 2 (AMSTAR-2) tool.

Results:

Of 2,197 meta-analyses, nine were included, providing evidence on 50 risk factors, 29,272 subjects with eating disorders, and 1,679,385 controls. Although no association was supported by convincing evidence, highly suggestive evidence supported the association between childhood sexual abuse and bulimia nervosa (k = 29, 1,103 cases with eating disorders, 8,496 controls, OR, 2.73, 95%CI 1.96-3.79, p = 2.1 x 10-9, AMSTAR-2 moderate quality) and between appearance-related teasing victimization and any eating disorder (k = 10, 1,341 cases with eating disorders, 3,295 controls, OR 2.91, 95%CI 2.05-4.12, p = 1.8x10-9, AMSTAR-2 moderate quality). Suggestive, weak, or no evidence supported 11, 29, and 8 associations, respectively.

Conclusions:

The most credible evidence indicates that early traumatic and stressful events are risk factors for eating disorders. Larger collaborative prospective cohort studies are needed to identify risk factors for eating disorders, particularly anorexia nervosa.

Reward and psychopathological correlates of eating disorders: The explanatory role of leptin

It has been hypothesized that leptin level alterations in Eating Disorders (EDs) represent a maintaining factor for pathological reward-related ED behaviors, given leptin role in the dopaminergic reward systems. The aim of the present study was to evaluate the role of leptin in EDs as a mediator for the relationship between Body Mass Index (BMI) and several pathological behaviors, such as dietary restraint, compensatory exercise, vomiting, binge eating and emotional eating. Sixty-two patients with EDs and 41 healthy controls (HC) had their blood drawn and completed psychometric tests for the evaluation of general psychopathology, ED psychopathology and emotional eating. Moderated linear regression models showed that, in the presence of high levels of ED psychopathology, leptin levels were negatively associated with dietary restraint and compensatory exercise, and positively with emotional eating and binge eating. Finally, leptin showed an indirect effect on the association between BMI and all these reward-related behaviors. These results suggest that a variation of BMI maintains these pathological ED behaviors through a variation in leptin levels. Considering the role of leptin in reward circuits, the results seem to confirm an aberrant food-related reward mechanism in ED patients.

Examining weight suppression as a transdiagnostic factor influencing illness trajectory in bulimic eating disorders

Recent research indicates that weight suppression (WS: defined as the difference between highest lifetime and current weight) prospectively predicts illness trajectory across eating disorders characterized by binge eating, including AN binge-purge subtype (ANbp), bulimia nervosa (BN), and binge eating disorder (BED), collectively referred to as bulimic eating disorders. Through a series of studies, we have developed a model to explain the link between WS and illness trajectory in bulimic eating disorders. Our model posits that WS contributes to reduced circulating leptin, which leads to reduced postprandial glucagon-like peptide 1 (GLP-1) response. Diminished leptin and GLP-1 function contribute to alterations in two reward-related constructs in the Research Domain Criteria (RDoC): reward value/effort and reward satiation. Respectively, these changes increase drive/motivation to consume food and decrease ability for food consumption to lead to a state of satiation/satisfaction. Combined, these alterations increase risk for experiencing large, out-of-control binge-eating episodes. The following review presents evidence that contributed to the development of this model as well as preliminary findings from an on-going project funded to test this model.

Medical Complications of Anorexia Nervosa and Bulimia Nervosa

Anorexia nervosa and bulimia nervosa are mental illnesses with associated complications affecting all body systems with arguably the highest mortality of all mental health disorders. A comprehensive medical evaluation is an essential first step in the treatment of anorexia nervosa and bulimia nervosa. Weight restoration and cessation of purging behaviors are often essential components in the management of medical complications of these illnesses.

Elevated total plasma-adiponectin is stable over time in young women with bulimia nervosa

Background

Bulimia nervosa (BN) is characterized by dysregulated eating behaviour and present data suggest adipokines may regulate food intake. We investigated a possible association between BN and adipokine levels and hypothesized that plasma (P)-adiponectin would be elevated and P-leptin and P-leptin-adiponectin-ratio would be reduced in women with BN.

Methods

The study was designed as a cross-sectional study with a longitudinal arm for patients with BN. Plasma-adiponectin and leptin was measured in 148 female patients seeking psychiatric ambulatory care and 45 female controls. Fifteen patients were diagnosed with BN and the remaining with other affective and anxiety disorders. P-adiponectin and P-leptin levels were compared between patients with BN, patients without BN and controls. At follow-up 1–2 years later, adipokines were reassessed in patients with BN and the Eating Disorder Examination Questionnaire was used to assess symptom severity.

Results

P-adiponectin was elevated in patients with BN at baseline and at follow-up when compared to patients without BN and controls (P < 0.004 and < 0.008 respectively). The difference remained significant after controlling for body mass index. P-adiponectin was correlated to symptom severity at follow-up in patients with BN without morbid obesity (ρ = 0.72, P < 0.04). P-leptin-adiponectin-ratio was significantly lower in patients with BN compared to controls (P < 0.04) and P-leptin non-significantly lower.

Conclusions

Findings indicate a stable elevation of P-adiponectin in women with BN. P-adiponectin at follow-up correlates to eating disorder symptom severity in patients without morbid obesity, indicating that P-adiponectin should be further investigated as a possible potential prognostic biomarker for BN.

Plasma leptin concentration is associated with fatigue severity in patients with cardiovascular risk factors - HSCAA study

Fatigue induced by complex dysfunctions of the central nervous system is frequently complained by patients with cardiovascular risk factors. Although leptin is considered to regulate the central nervous system, there are no reports regarding its association with fatigue in those patients. This cross-sectional study included 347 patients with cardiovascular risk factors. Fatigue score and plasma leptin concentration were measured. In addition, abdominal fat accumulation, systemic inflammation, sleep condition, and functions of hypothalamus-pituitary axis and autonomic system were estimated. Plasma leptin concentration (natural logarithm transformed) was significantly and positively (r=0.222, p<0.001) associated with fatigue score, and significantly (p<0.001) higher in the moderately-fatigued group (2.32±0.75ng/ml, mean±SD, n=52) than in the normally-fatigued group (1.85±1.02ng/ml, mean±SD, n=295). Multiple logistic regression analysis showed that plasma leptin concentration was significantly and independently associated with a moderately-fatigued condition independent of other factors, including age, gender, presence of diabetes, hypertension, dyslipidemia, alcohol consumption habit, urinary free cortisol, serum high-sensitive CRP concentration, visceral and subcutaneous fat area, apnea/hypopnea index, sleep efficiency, and heart rate variability. Hyperleptinemia may contribute to fatigue severity in patients with cardiovascular risk factors.

Weight suppression in bulimia nervosa: Associations with biology and behavior

Bulimia nervosa (BN) is a serious eating disorder that can persist for years and contribute to medical complications and increased mortality, underscoring the need to better understand factors maintaining this disorder. Higher levels of weight suppression (WS) have been found to predict both the onset and maintenance of BN; however, no studies have examined mechanisms that may account for the effects of WS on BN. We hypothesized that high WS would lead to reduced leptin levels, which may increase risk of binge eating by modulating reward responses to food. The current study examined the relationship between WS, leptin levels, and the reinforcing value of food in women with BN (n = 32) and noneating disorder controls (n = 30). Participants provided information on WS, completed a fasting blood draw to obtain serum leptin, and completed a progressive ratio task to measure the reinforcing value of food. Individuals with BN had greater WS (p < .01) and reinforcing food value (p < .05) compared with controls. Additionally, higher WS was associated with both lower leptin (p < .05) and increased reinforcing value of food (p < .05). Contrary to hypotheses, BN and control participants did not differ on leptin levels, and leptin levels were not significantly associated with the reinforcing value of food. Findings support that efforts to conform to the thin ideal may alter drive to consume rewarding foods and leave women vulnerable to binge episodes. However, mechanisms through which WS contributes to food reward and binge eating remain unknown.

Dysfunctions of leptin, ghrelin, BDNF and endocannabinoids in eating disorders: beyond the homeostatic control of food intake

A large body of literature documents the occurrence of alterations in the physiology of both central and peripheral modulators of appetite in acute patients with anorexia nervosa (AN) and bulimia nervosa (BN). Until more recently the role of most of the appetite modulators in the control of eating behavior was conceptualized solely in terms of their influence on homeostatic control of energy balance. However, it is becoming more and more evident that appetite modulators also affect the non-homeostatic cognitive, emotional and rewarding component of food intake as well as non food-related reward, and, recently, AN and BN have been pathophysiologically linked to dysfunctions of reward mechanisms. Therefore, the possibility exists that observed changes in appetite modulators in acute AN and BN may represent not only homeostatic adaptations to malnutrition, but also contribute to the development and/or the maintenance of aberrant non-homeostatic behaviors, such as self-starvation and binge eating. In the present review, the evidences supporting a role of leptin, ghrelin, brain-derived neurotrophic factor and endocannabinoids in the homeostatic and non-homeostatic dysregulations of patients with AN and BN will be presented. The reviewed literature is highly suggestive that changes in the physiology of these modulators may play a pivotal role in the pathophysiology of eating disorders by providing a possible link between motivated behaviors, reward processes, cognitive functions and energy balance.

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.

Leptin as a neuroactive agent

OBJECTIVE

To review the literature regarding the role of leptin in psychiatric disorders.

METHODS

A PubMed search was undertaken using the following keywords: leptin, psychosis, affective disorders, alcohol, psychiatry, depression, dementia, and eating disorders. The articles were restricted to the English language.

RESULTS

The role of leptin in psychiatric populations has been the subject of increasing investigation. Basic science and clinical observations support a role for leptin in mediating cognition and reward processes. The role of leptin in psychiatric illnesses characterized by cognitive deficits has gained increased attention in recent years. Leptin deficiency and resistance have also been associated with eating disorders as well as affective, alcohol dependence, and psychotic disorders. The mechanisms underlining these associations remain to be determined.

CONCLUSIONS

Clinical research suggests an important role of leptin in psychiatric illnesses. Given the morbidity associated with mental illness, clinical research on the role of leptin and related novel therapeutic modalities is needed.

Psychobiology of purging disorder: reduction in circulating leptin levels in purging disorder in comparison with controls

OBJECTIVE

Purging disorder (PD), a recently recognized eating disorder syndrome, is differentiated from bulimia nervosa (BN) based on the absence of objectively large binge episodes. BN has been associated with low serum leptin levels. This study examined whether PD is also characterized by low serum leptin.

METHOD

Participants included women with PD (n = 20) or BN (n = 37), and non-eating disorder controls (n = 33). Blood samples for measurement of leptin and total ghrelin were obtained after overnight fast.

RESULTS

In comparison with control values, leptin levels were significantly decreased in PD (p < .01), as well as in BN (p < .02). Plasma ghrelin levels did not differ significantly across groups.

DISCUSSION

These results provide the first evidence that PD is associated with alteration in a neurobiological pathway influencing eating patterns and body weight. Further research is needed to assess whether low leptin levels in PD and BN are associated with restrained eating and weight suppression.

Neuroendocrine dysregulation of food intake in eating disorders

Anorexia nervosa (AN) and bulimia nervosa (BN) are psychiatric disorders characterized by abnormal eating behaviors and imbalance of energy homeostasis. Changes of both central and peripheral neuroendocrine substances involved in the modulation of food intake and energy expenditure have been described in acutely ill patients with eating disorders. This review selectively focuses on the most recent findings supporting abnormal changes in the physiology of some peripheral adipokines and gut-secreted peptides, brain-derived neurotrophic factor and endocannabinoids in patients with AN or BN. Literature data do suggest a dysregulation of these neuroendocrine feeding regulators but, at the moment, they do not allow to establish the state or trait-dependent nature of those aberrations. It has been proposed, although not definitively proved, that neuroendocrine alterations, even when secondary to malnutrition and/or to aberrant eating behaviors, might contribute to the genesis and the maintenance of some symptomatic aspects of AN and BN, thus affecting the course and the prognosis of these disorders. Future studies should clarify whether neuroendocrine alterations are part of the genetically transmitted biological vulnerability to eating disorders.

Phenotypes, endophenotypes, and genotypes in bulimia spectrum eating disorders

OBJECTIVES

To review the main phenomenological variants observed among bulimia spectrum syndromes and the factors believed to act etiologically for them and also to generate an etiologic model that accommodates known heterogeneities within the population suffering bulimic syndromes.

METHOD

Defining bulimic syndromes broadly, we address threshold and subthreshold forms of bulimia nervosa (BN) and also the provisional or newly proposed diagnoses of binge eating disorder (BED) and purging disorder (PD). We review evidence bearing on the validity of these diagnostic entities and on the place of sociocultural, family-developmental, neurobiological, and genetic factors in a multidimensional etiologic model for these classifications.

RESULTS

Available data validate certain bulimic phenotypes and subphenotypes that are characterized by such traits as impulsivity or affective instability. Findings associate subphenotypic, or trait-based, variations with putative endophenotypes, such as reduced serotonin transporter activity, and with candidate genotypes affecting the serotonin system; the data also indicate intriguing correspondences between gene environment interactions and subphenotypic variations along such dimensions as novelty seeking.

CONCLUSIONS

Bulimic syndromes sometimes reflect a primary disruption of controls over mood, impulses, and appetite in individuals showing marked psychopathology; at other times, they reflect a more circumscribed erosion of appetitive controls in relatively intact individuals, following prolonged dieting. We argue that dimensional perspectives involving careful attention to comorbid personality traits and symptoms are needed to accommodate existing heterogeneities within the population suffering from bulimia and to characterize the etiologic roles of familial-developmental, neurobiological, and genetic variables (and of interactions among these variables) in bulimic syndromes.

Ghrelin concentrations and cardiac vagal tone are decreased after pharmacologic and cognitive-behavioral treatment in patients with bulimia nervosa

Patients with bulimia nervosa (BN) have bulimic and depressive symptoms, which have been associated with abnormalities in the neuroendocrine and vagal systems. Subjects included twenty-four female drug-free outpatients with BN that were selected from patients seeking treatment for eating behavior in our hospital along with twenty-five age-matched healthy females who served as controls. We investigated ghrelin and leptin levels, cardiac vagal tone and sympathovagal balance, frequency of sets of binge-eating and vomiting episodes per week and the Profile of Mood States (POMS) depression scale in BN before and after a 16-week administration of the serotonin selective reuptake inhibitor (SSRI) paroxetine combined with cognitive-behavioral therapy. Compared to controls, the BN group had higher ghrelin levels and resting cardiac vagal tone, and lower leptin levels and resting cardiac sympathovagal balance before treatment, although there was a significant difference between the two groups for the body mass index (BMI). The elevated ghrelin levels (301.7 +/- 18.9 pmol/l, mean +/- SEM vs. 202.8 +/- 15.6 pmol/l, P < 0.01), cardiac vagal tone (2246.4 +/- 335.5 ms(2) vs. 1128.5 +/- 193.3 ms(2), P < 0.01), frequency of sets of binge-eating and purging episodes and T scores for the POMS depression scale were all significantly decreased after treatment despite similar BMI, percent body fat and leptin levels. In close association with cardiac vagal function and ghrelin recoveries, abnormal eating behavior and depressive symptoms improved, indicating the usefulness of these indexes in the assessment of clinical condition and therapeutic efficacy in BN.

Correlation between psychometric and biological parameters in anorexic and bulimic patients during and after an intensive day hospital treatment

This study describes: 1. The therapeutic effects on anorexia nervosa (AN) and bulimia nervosa (BN) patients of a psycho-nutritional intensive day-hospital program; 2. The possible correlation between the changes observed in the psychometric tests and the variations of a number of biological parameters. Forty-six female patients (24 AN and 22 BN) were assessed through a semi-structured clinical interview based on DSM-IV criteria for Eating Disorders (ED) and a number of psychometric tests (SCL-90R, BDI, EDI-2, EAT-40, BITE, BAT) at the beginning and at the end of treatment, and after a 6-month follow-up. At these three times, we also assessed the plasma level of leptin, cortisol, luteinizing hormone (LH), follicle-stimulating hormone (FSH) and 17beta-estradiol together with body mass index (BMI) and menstrual cycle. From beginning to discharge, the scores on all psychometric tests improved in the whole sample, except for the Perfectionism subscale of EDI-2 in both groups (AN and BN), the Anger-Hostility, Phobic Anxiety and Paranoid Ideation subscales of SCL-90 and the Interpersonal Distrust subscale of EDI-2 in the BN group. At follow-up, there was a worsening of the BITE scores and of a number of EDI-2 subscales, especially in the AN subgroup - with these changes correlating with the trend of BMI. In AN patients, plasma leptin levels changed from the beginning to the end of treatment and at follow-up according to BMI changes. The mean plasma leptin level in the BN subgroup was higher than in the AN one. We found a statistically significant correlation with the scores of BDI, SCL-90R Depression and Ineffectiveness subscales, EAT-40, BITE-Symptom subscale and the trend of menses dividing these patients into two subgroups (according to the plasma leptin concentration, higher or lower than the top leptin level in the anorexics). These data seem to confirm that leptin secretion doesn't correlate univocally to BMI.

Eating disorders: clinical features and pathophysiology

Anorexia nervosa (AN) and bulimia nervosa (BN) are disorders of eating and weight-related behavior that together afflict some 1-3% of women in the United States. One of the remarkable features about each of the eating disorders is how persistent the disordered eating behavior becomes once it has begun. Substantial psychological, social, and physiological disturbances are associated with eating disorders, and it has been very difficult to disentangle those factors that may result from the disturbed behavior from the factors that may have predisposed individuals to, or precipitated the development of, the disorder. This article will briefly review the definitions, phenomenology, and identified risk factors for development of each of the major eating disorders. Pathophysiology will be discussed, with a particular focus on candidate factors that might sustain disordered eating behavior, as informed by clinical and basic science research. Future research directions will be suggested.

Effect of dieting on plasma leptin, soluble leptin receptor, adiponectin and resistin levels in healthy volunteers

OBJECTIVE

Recent findings demonstrating important effects of the adipokines on metabolism, energy homeostasis and body weight regulation have prompted research on the possible role of negative energy balance in altering adipocytokine regulation. The goal of this study was to evaluate the effects of a hypocaloric diet in healthy normal-weight volunteers. An additional goal was to help clarify the contribution of restricted caloric intake to altered plasma adipokine levels in the eating disorders anorexia nervosa and bulimia nervosa.

DESIGN

Participants were studied before and after a 4-week reduced-calorie diet (1000-12000 kcal/day). patients Subjects included 15 healthy, normal-weight women (age 22 +/- 3 years).

MEASUREMENTS

Plasma concentrations of leptin, soluble leptin receptor protein (sOB-R), adiponectin, resistin, thyroid hormones and beta-hydroxybutyrate were determined following overnight fast before and after the 4-week reduced-calorie diet.

RESULTS

Subjects lost a mean of 3.4 +/- 2.1 kg in response to the reduced-calorie diet. The weight loss phase was associated with a 60.3% decrease in plasma leptin levels (P < 0.001), a 43.5% increase in sOB-R levels (P < 0.002) and a 16.2% decrease in plasma adiponectin levels (P < 0.04). There was no significant change in plasma resistin levels.

CONCLUSIONS

These results demonstrate that a modest decrease in energy intake sustained over several weeks may play an important role in altering levels of plasma leptin and sOB-R. The findings also provide preliminary evidence that, in contrast to previous results in obese subjects, caloric restriction with accompanying weight loss in healthy, normal-weight volunteers may lead to decreased circulating adiponectin levels. Additional studies will be needed to clarify the contribution of altered energy intake to abnormalities in cytokine levels in the eating disorders.

Leptin functioning in eating disorders

Leptin is an adipocyte-derived hormone, which is involved predominantly in the long-term regulation of body weight and energy balance by acting as a hunger suppressant signal to the brain. Leptin is also involved in the modulation of reproduction, immune function, physical activity, and some endogenous endocrine axes. Since anorexia nervosa (AN) and bulimia nervosa (BN) are characterized by abnormal eating behaviors, dysregulation of endogenous endocrine axes, alterations of reproductive and immune functions, and increased physical activity, extensive research has been carried out in the last decade in order to ascertain a role of this hormone in the pathophysiology of these syndromes. In this article, we review the available data on leptin physiology in patients with eating disorders. These data support the idea that leptin is not directly involved in the etiology of AN or BN. However, malnutrition-induced alterations in its physiology may contribute to the genesis and/or the maintenance of some clinical manifestations of AN and BN and may have an impact on the prognosis of AN.

Hyperleptinemia in subjects with persistent partial posttraumatic stress disorder after a major earthquake

OBJECTIVE

Leptin, a peptide hormone derived from adipose tissue, regulates food intake and controls weight. Serum leptin levels may be elevated in critically ill patients and in cases of physical stress. Our aim was to examine the relationship between postdisaster psychiatric symptoms and serum leptin levels.

METHODS

We recruited 92 subjects who visited emergency medical stations immediately after the giant earthquake seized middle Taiwan on September 21, 1999. Of these cases, 43 met the criteria for subsyndromal acute stress disorder. Eighteen months later, we measured serum leptin levels and performed in-depth psychiatric assessments using the posttraumatic stress disorder subset in the Mini International Neuropsychiatric Instrument and the Brief Symptom Rating Scale short form.

RESULTS

After we adjusted for age, gender, and body mass index, serum leptin levels were significantly higher in the persistent subsyndromal group (N = 15; estimated marginal mean, 9.641; 95% confidence interval, 7.673-11.610) than in others (estimated marginal means, 4.775-6.368). A hyperaroused state predicted a higher adjusted leptin level. On the Brief Symptom Rating Scale, general severity index, paranoid tendency, anxiety symptoms, and depressive symptoms were positively correlated with adjusted leptin levels.

CONCLUSIONS

We found a direct relationship between stress-related psychopathologic symptoms and serum leptin levels. Subjects with persistent subsyndromal posttraumatic stress disorder and hyperarousal had significantly higher serum leptin levels. Therefore, leptin may be a valid neuroendocrinologic marker for the hypervigilant state of vulnerable people who have faced tremendous danger and uncertainty. Further studies are needed to examine the correlation between leptin levels and hypothalamic-pituitary-adrenal axis function, particularly the inverted diurnal serum leptin levels in hyperaroused subjects.

Opposite modifications in circulating leptin and soluble leptin receptor across the eating disorder spectrum

Leptin is thought to modulate feeding behaviour, body weight and energy metabolism by acting through specific cellular receptors. Derangements of leptin production have been repeatedly reported in patients with anorexia nervosa (AN) or bulimia nervosa (BN), but no information has been provided on the functional status of leptin receptors in these disorders. Therefore, we measured plasma levels of leptin and its soluble receptor (Ob-Re) in a total of 130 women, including 22 patients with AN, 45 patients with BN, 18 patients with the binge-eating disorder (BED), 12 non-binge eating obese women and 33 healthy women. Circulating leptin was drastically reduced in underweight anorexics and normal-weight bulimics, but increased in overweight BED patients and non-binge-eating obese women. Conversely, plasma levels of Ob-Re were significantly increased in patients with AN or BN, but decreased in BED and non-binge-eating obese women. Significant inverse correlations were detected between plasma levels of leptin and those of Ob-Re in all the subject groups, except in non-binge-eating obese subjects. These results show, for the first time, that opposite modifications occur in circulating levels of leptin and Ob-Re across the eating-disorder spectrum. The relevance of these findings to the pathophysiology and treatment of eating disorders remains to be elucidated.

The human genetics of eating disorders lessons from the leptin/melanocortin system

Genetic analysis of eating disorders is complex phenotypically and genotypically. As seen in the leptin/melanocortin system, however, the results can lead to a deeper understanding and to new therapies. Benefits are expected for eating disorders that stem from genetic and psychologic causes. Finally, an awareness of possible genetic causes of eating disorders will help determine the causes--and thus the treatments--in children and adolescents with eating disorders, as exemplified by obese patients with mutations in the POMC, PC1, leptin, and MC4R loci.

Bulimia in children and adolescents

Although there have been many recent advances in research, much work remains to be done in the area of child and adolescent eating disorders. More data are needed regarding the normal development of eating behavior, resilience and risk factors for eating pathology, and treatment studies in children and adolescents. The best studied areas include epidemiology, short-term treatment for bulimia nervosa (BN), and outcome in anorexia nervosa. A case report of the single blind use of repetitive transcranial magnetic stimulation in a patient with BN has been reported, but its safe use in children and adolescents remains to be established.

Leptin and reproduction: a review

OBJECTIVE

To review recent advances in understanding the role of leptin in the physiology and pathophysiology of reproduction, with a focus on relevant clinical situations.

DESIGN

A MEDLINE computer search was performed to identify relevant articles.

RESULT(S)

Leptin, an adipocyte hormone important in regulating energy homeostasis, interacts with the reproductive axis at multiple sites, with stimulatory effects at the hypothalamus and pituitary and inhibitory actions at the gonads. More recently, leptin has been shown to play a role in other target reproductive organs, such as the endometrium, placenta, and mammary gland, with corresponding influences on important physiologic processes such as menstruation, pregnancy, and lactation. As a marker of whether nutritional stores are adequate, leptin may act in concert with gonadotropins and the growth hormone axis to initiate the complex process of puberty. Conditions in which nutritional status is suboptimal, such as eating disorders, exercise-induced amenorrhea, and functional hypothalamic amenorrhea, are associated with low serum leptin levels; and conditions with excess energy stores or metabolic disturbances, such as obesity and polycystic ovarian syndrome, often have elevated serum or follicular fluid leptin levels, raising the possibility that relative leptin deficiency or resistance may be at least partly responsible for the reproductive abnormalities that occur with these conditions.

CONCLUSION(S)

Leptin may act as the critical link between adipose tissue and the reproductive system, indicating whether adequate energy reserves are present for normal reproductive function. Future interventional studies involving leptin administration are expected to further clarify this role of leptin and may provide new therapeutic options for the reproductive dysfunction associated with states of relative leptin deficiency or resistance.

Serum leptin level and restrained eating: study with the Eating Disorder Examination

Serum leptin concentrations in obese patients are influenced at short-term by a reduction of food intake. The objective of this investigation was to evaluate the relationship between serum leptin level and eating behavior. The eating behavior and the food and shape attitudes of a group of obese women were assessed by the Eating Disorder Examination (EDE), and the subscale scores were correlated with serum leptin levels. No difference in serum leptin level was found between obese patients with binge eating disorder (BED) and their nonbingeing counterparts. Considering all patients, the serum leptin levels positively correlated with the body mass index values (BMI), and the EDE subscales scores were positively interrelated. After controlling for BMI, serum leptin level was negatively correlated with the EDE Restraint score and positively correlated with the EDE Shape Concern score. The findings of this investigation indicate that in obese women serum leptin level and the occurrence of binge eating are unrelated. Furthermore, this study also found that the relationship between serum leptin level and restraint over food intake observed in eating disordered patients and in overweight preadolescent girls is shared by obese adult women. In addition, the positive relationship between EDE Shape Concern and serum leptin concentration suggests that the restrained eating might be the cause rather the consequence of the low leptin production.

Leptin in anorexia nervosa and bulimia nervosa: importance of assay technique and method of interpretation

Studies of the role of leptin in patients with anorexia nervosa and bulimia nervosa have conflicted in their data and interpretation. Such differences may be a result of the assay methods used or the way results are compared with those from normal controls. To investigate these possibilities, we analyzed serum leptin levels in anorexic, bulimic, obese, and control individuals, thereby spanning the full range of human body weights, using three frequently employed commercial kits. Kits from Linco (St Louis, MO) and DSL (Webster, TX) employ a radioimmunoassay method, and the R&D Systems kit (Minneapolis, MN) uses an enzyme-linked immunosorbent assay. We found that the three kits provide results that are highly linearly correlated with each other and remarkably linearly related to percent ideal body weight (%IBW) over more than three orders of magnitude (Linco, r = 0.90; R&D, r = 0.87; DSL, r = 0.86). For very low leptin levels, the more sensitive kits from R&D and Linco appeared to give more reliable results. Measurement method does not appear to explain the literature conflicts. We found that patients with anorexia nervosa have serum leptin values that lie above the line extrapolated from the %IBW/leptin curve generated from analysis of all non-anorexic patients. Therefore, in anorexia nervosa, inappropriately high leptin levels for %IBW may contribute to a blunted physiologic response to underweight and consequent resistance to dietary treatment. By contrast, most bulimic patients have leptin levels significantly below those predicted from the same %IBW/leptin curve. The relative leptin deficiency in bulimic subjects may contribute to food-craving behavior. We propose that using the %IBW/ leptin curve can facilitate identification of true pathophysiologic abnormalities in eating-disordered individuals and provide a basis for the design of therapeutic interventions or monitoring of response to treatment.

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

Bulimia nervosa is an eating disorder characterised by recurrent episodes of binge eating and associated efforts to purge the ingested calories through self-induced vomiting, laxative or diuretic abuse, fasting or intensive exercise. The aetiopathogenesis and pathophysiology of the disorder are currently unclear. Biological bases have been proposed repeatedly, based on several lines of evidence: hunger, satiety and food choice are regulated by neurotransmitters and neuropeptides, and impairment of eating habits may be related to alterations in the secretion of these chemicals; genetic studies suggest that these neurotransmitter systems are dysfunctional in individuals with bulimia nervosa; and the frequent comorbidity of bulimia nervosa with major depressive and obsessive-compulsive disorders, conditions in which multiple alterations of brain biochemical functions have been demonstrated. Data in the literature suggest that levels of noradrenaline (norepinephrine) and serotonin (5-hydroxytryptamine; 5-HT) are lower in individuals with bulimia nervosa than in healthy controls. Levels of dopamine are similar to, or lower than, those in controls. After remission of the disorder, noradrenergic function returns to that seen in controls, whereas dopaminergic and serotonergic function rebound to levels higher than in controls. Among the neuropeptides, alterations in the levels of neuropeptide Y, peptide YY, beta-endorphin, corticotrophin-releasing hormone, somatostatin, cholecystokinin and vasopressin have been found in the symptomatic phase of bulimia nervosa, with a return to levels seen in controls after remission. Pharmacological treatment of bulimia nervosa that is directed at correction of the neurochemical alterations observed is difficult because of the complexity of the impairments. However, such treatment is necessary and should be continued long after symptomatic remission to ensure reinstitution of cerebral biochemical homeostasis.