Disentangling the links between gastric emptying and binge eating v. purging in eating disorders using a case-control design

BACKGROUND

Prior work supports delayed gastric emptying in anorexia nervosa and bulimia nervosa (BN) but not binge-eating disorder, suggesting that neither low body weight nor binge eating fully accounts for slowed gastric motility. Specifying a link between delayed gastric emptying and self-induced vomiting could offer new insights into the pathophysiology of purging disorder (PD).

METHODS

Women (N = 95) recruited from the community meeting criteria for DSM-5 BN who purged (n = 26), BN with nonpurging compensatory behaviors (n = 18), PD (n = 25), or healthy control women (n = 26) completed assessments of gastric emptying, gut peptides, and subjective responses over the course of a standardized test meal under two conditions administered in a double-blind, crossover sequence: placebo and 10 mg of metoclopramide.

RESULTS

Delayed gastric emptying was associated with purging with no main or moderating effects of binge eating in the placebo condition. Medication eliminated group differences in gastric emptying but did not alter group differences in reported gastrointestinal distress. Exploratory analyses revealed that medication caused increased postprandial PYY release, which predicted elevated gastrointestinal distress.

CONCLUSIONS

Delayed gastric emptying demonstrates a specific association with purging behaviors. However, correcting disruptions in gastric emptying may exacerbate disruptions in gut peptide responses specifically linked to the presence of purging after normal amounts of food.

Satiation deficits and binge eating: Probing differences between bulimia nervosa and purging disorder using an ad lib test meal

Purging disorder (PD) has been included as a named condition within the DSM-5 category of Other Specified Feeding or Eating Disorder and differs from bulimia nervosa (BN) in the absence of binge-eating episodes. The current study evaluated satiation through behavioral and self-report measures to understand how this construct may explain distinct symptom presentations for bulimia nervosa (BN) and purging disorder (PD). Women (N = 119) were recruited from the community if they met DSM-5 criteria for BN (n = 57), PD (n = 31), or were free of eating pathology (n = 31 controls). Participants completed structured clinical interviews and questionnaires and an ad lib test meal during which they provided reports of subjective states. Significant group differences were found on self-reported symptoms, ad lib test meal intake, and subjective responses to food intake between individuals with eating disorders and controls and between BN and PD. Further, ad lib intake was associated with self-reported frequency and size of binge episodes. In a multivariable model, the amount of food consumed during binges as reported during clinical interviews predicted amount of food consumed during the ad lib test meal, controlling for other binge-related variables. Satiation deficits distinguish BN from PD and appear to be specifically linked to the size of binge episodes. Future work should expand exploration of physiological bases of these differences to contribute to novel interventions.

Disturbance of gut satiety peptide in purging disorder

OBJECTIVE

Little is known about biological factors that contribute to purging after normal amounts of food-the central feature of purging disorder (PD). This study comes from a series of nested studies examining ingestive behaviors in bulimic syndromes and specifically evaluated the satiety peptide YY (PYY) and the hunger peptide ghrelin in women with PD (n = 25), bulimia nervosa-purging (BNp) (n = 26), and controls (n = 26). Based on distinct subjective responses to a fixed meal in PD (Keel, Wolfe, Liddle, DeYoung, & Jimerson, ), we tested whether postprandial PYY response was significantly greater and ghrelin levels significantly lower in women with PD compared to controls and women with BNp.

METHOD

Participants completed structured clinical interviews, self-report questionnaires, and laboratory assessments of gut peptide and subjective responses to a fixed meal.

RESULTS

Women with PD demonstrated a significantly greater postprandial PYY response compared to women with BNp and controls, who did not differ significantly. PD women also endorsed significantly greater gastrointestinal distress, and PYY predicted gastrointestinal intestinal distress. Ghrelin levels were significantly greater in PD and BNp compared to controls, but did not differ significantly between eating disorders. Women with BNp endorsed significantly greater postprandial hunger, and ghrelin predicted hunger.

DISCUSSION

PD is associated with a unique disturbance in PYY response. Findings contribute to growing evidence of physiological distinctions between PD and BNp. Future research should examine whether these distinctions account for differences in clinical presentation as this could inform the development of specific interventions for patients with PD.

Impaired reversal learning in an animal model of anorexia nervosa

BACKGROUND

Clinical investigations indicate that anorexia nervosa (AN) is associated with impaired cognitive flexibility. Activity-based anorexia (ABA), a rodent behavioral model of AN, is characterized by compulsive wheel running associated with voluntary food restriction and progressive weight loss. The goal of this study was to test whether ABA is associated with impaired cognitive flexibility.

METHODS

Female Sprague-Dawley rats were trained to perform the attentional set-shifting test (ASST) to assess cognitive flexibility, including capacity for set-shifting and reversal learning. Rats were assigned to ABA or weight-loss paired control (WPC) conditions. Following baseline testing, the ABA group had access to food for 1h/d and access to running wheels 23h/d until 20% weight loss was voluntarily achieved. For the WPC group, running wheels were locked and access to food was restricted to reduce body weight at the same rate as the ABA group. ASST performance was assessed after weight loss, and again following weight recovery.

RESULTS

Compared to baseline, the ABA group (but not the WPC group) showed a significant decrement in reversal learning at low weight, with return to baseline performance following weight restoration. The other components of ASST were not affected.

CONCLUSIONS

Impaired reversal learning, indicative of increased perseverative responding, in the ABA model reveals its potential to recapitulate selective components of cortical dysfunction in AN. This finding supports the utility of the ABA model for investigations of the neural mechanisms underlying such deficits. Reversal learning relies on neural circuits involving the orbitofrontal cortex and thus the results implicate orbitofrontal abnormalities in AN-like state.

Plasma BDNF levels following weight recovery in anorexia nervosa

OBJECTIVE

Preclinical studies have implicated brain-derived neurotrophic factor (BDNF) in the regulation of eating behavior and body weight. As reviewed in this report, prior studies of BDNF levels in anorexia nervosa have yielded variable results, perhaps reflecting effects of malnutrition and psychiatric comorbidity. The goal of the current report was to assess plasma BDNF as a biomarker in weight-recovered individuals with a history of anorexia nervosa (ANWR).

METHODS

Study groups included women meeting criteria for ANWR and healthy female controls. Participants were in a normal weight range, free of current major psychiatric disorder, and free of medication. Self-ratings included eating disorder symptoms, depression and anxiety. Plasma BDNF levels were measured by enzyme linked immunoassay.

RESULTS

Plasma BDNF levels were not significantly different for ANWR and control groups. Plasma BDNF levels were inversely correlated with anxiety ratings in controls (p<0.02) but not in the ANWR group.

DISCUSSION

This report provides new evidence that circulating BDNF concentrations do not differ in healthy controls and ANWR free of psychiatric comorbidity. Additionally, the data provide new information on the relationship between plasma BDNF and anxiety in these two study groups.

Initial evaluation, diagnosis, and treatment of anorexia nervosa and bulimia nervosa

Eating disorders are life-threatening conditions that are challenging to address; however, the primary care setting provides an important opportunity for critical medical and psychosocial intervention. The recently published Diagnostic and Statistical Manual of Mental Disorders, 5th ed., includes updated diagnostic criteria for anorexia nervosa (e.g., elimination of amenorrhea as a diagnostic criterion) and for bulimia nervosa (e.g., criterion for frequency of binge episodes decreased to an average of once per week). In addition to the role of environmental triggers and societal expectations of body size and shape, research has suggested that genes and discrete biochemical signals contribute to the development of eating disorders. Anorexia nervosa and bulimia nervosa occur most often in adolescent females and are often accompanied by depression and other comorbid psychiatric disorders. For low-weight patients with anorexia nervosa, virtually all physiologic systems are affected, ranging from hypotension and osteopenia to life-threatening arrhythmias, often requiring emergent assessment and hospitalization for metabolic stabilization. In patients with frequent purging or laxative abuse, the presence of electrolyte abnormalities requires prompt intervention. Family-based treatment is helpful for adolescents with anorexia nervosa, whereas short-term psychotherapy, such as cognitive behavior therapy, is effective for most patients with bulimia nervosa. The use of psychotropic medications is limited for anorexia nervosa, whereas treatment studies have shown a benefit of antidepressant medications for patients with bulimia nervosa. Treatment is most effective when it includes a multidisciplinary, teambased approach.

Emotion contagion moderates the relationship between emotionally-negative families and abnormal eating behavior

OBJECTIVE

To reconcile empirical inconsistencies in the relationship between emotionally-negative families and daughters' abnormal eating, we hypothesized a critical moderating variable: daughters' vulnerability to emotion contagion.

METHOD

A nonclinical sample of undergraduate females (N = 92) was recruited via an advertisement and completed self-report measures validated for assessing: families' expressive negativity, daughters' susceptibility to emotion contagion, dietary restraint, and disinhibition, eating attitudes, and several control variables (interpersonal orientation, alexithymia, and the big five personality traits: extraversion, conscientiousness, openness, neuroticism, and agreeableness).

RESULTS

All variables and interactions were entered as predictors in a multistep multiple regression equation. Only an emotion contagion by family expressivity interaction term significantly predicted unhealthy eating attitudes (β = .29, p = .02) and dietary restraint (β = .27, p = .03). Negatively expressive families significantly induced unhealthy eating and restraint but only among young women susceptible to emotion contagion (ps < .05).

DISCUSSION

Young women susceptible to emotion contagion may be at increased risk for eating disorders.

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.

Co-morbidity and disorder-related distress and impairment in purging disorder

BACKGROUND

Recent studies suggest that purging disorder (PD) may be a common eating disorder that is associated with clinically significant levels of distress and high levels of psychiatric co-morbidity. However, no study has established evidence of disorder-related impairment or whether distress is specifically related to PD rather than to co-morbid disorders.

METHOD

Three groups of normal-weight women [non-eating disorder controls (n=38), with PD (n=24), and with bulimia nervosa (BN)-purging subtype (n=57)] completed structured clinical interviews and self-report assessments.

RESULTS

Both PD and BN were associated with significant co-morbidity and elevations on indicators of distress and impairment compared to controls. Compared to BN, PD was associated with lower rates of current and lifetime mood disorders but higher rates of current anxiety disorders. Elevated distress and impairment were maintained in PD and BN after controlling for Axis I and Axis II disorders.

CONCLUSIONS

PD is associated with elevated distress and impairment and should be considered for inclusion as a provisional disorder in nosological schemes such as the Diagnostic and Statistical Manual to facilitate much-needed research on this clinically significant syndrome.

State self-esteem ratings in women with bulimia nervosa and bulimia nervosa in remission

OBJECTIVE

Bulimia nervosa (BN) is associated with low self-esteem. This study was designed to assess whether low self-esteem persists in nondepressed individuals who have recovered from BN (BN-R).

METHOD

Study groups included BN (n = 22), BN-R (n = 20), and healthy controls (n = 42). Participants were medication-free, and none met criteria for current major depression. Assessment instruments included the State Self-Esteem Scale (SSES), a self-rating scale designed to measure state-related changes in self-esteem.

RESULTS

Consistent with previous reports, SSES scores for BN were lower than for controls (p < .001). For BN-R, SSES scores were higher than for BN (p < .001), but lower than for controls (p < .025). For BN-R, scores on the SSES Appearance subscale were inversely correlated with ratings of dietary restraint (p < .005).

CONCLUSION

This study provides new evidence for persistent low self-esteem following recovery from BN. Follow-up studies are needed to assess whether low self-esteem contributes to recurrent dieting and risk for relapse.

The effects of type 1 diabetes on cerebral white matter

AIM/HYPOTHESIS

Studies investigating the structure, neurophysiology and functional outcomes of white matter among type 1 diabetes patients have given conflicting results. Our aim was to investigate the relationship between type 1 diabetes and white matter hyperintensities.

METHOD

We assessed white matter integrity (using magnetic resonance imaging), depressive symptoms and neuropsychological function in 114 type 1 diabetes patients and 58 age-matched non-diabetic controls.

RESULTS

Only Fazekas grade 1 and 2 white matter hyperintensities were found among 114 long-duration, relatively young diabetes patients; the severity of lesions did not differ substantially from 58 healthy controls. White matter hyperintensities were not associated with depressive history or with clinical characteristics of diabetes, including retinopathy, severe hypoglycaemia or glycaemia control.

CONCLUSIONS/INTERPRETATION

Our data do not support an association between diabetes characteristics and white matter hyperintensities among relatively young type 1 diabetes participants.

Clinical features and physiological response to a test meal in purging disorder and bulimia nervosa

CONTEXT

Recent data suggest that purging disorder, a recently characterized form of eating disorder not otherwise specified, may be worthy of specific delineation in nosological schemes. However, more data are needed to determine how purging disorder differs from bulimia nervosa.

OBJECTIVE

To examine clinical features and subjective as well as objective physiological responses to a standardized test meal in purging disorder compared with bulimia nervosa and controls.

DESIGN

Study visit 1 included psychological assessments with structured clinical interviews and questionnaires. Study visit 2 included assessment of test-meal responses.

SETTING

Participants recruited from the community completed test-meal studies in a General Clinical Research Center.

PARTICIPANTS

Women with DSM-IV bulimia nervosa-purging subtype (n = 37) and purging disorder (n = 20) and non-eating disorder controls (n = 33) with a body mass index (calculated as weight in kilograms divided by height in meters squared) between 18.5 and 26.5 who were free of psychotropic medications.

MAIN OUTCOME MEASURES

Assessments of eating disorder severity, postprandial cholecystokinin response, and subjective responses to test meals.

RESULTS

Eating abnormalities were significantly elevated in participants with purging disorder and bulimia nervosa compared with controls but did not differ between eating disorder groups. Participants with purging disorder demonstrated significantly greater postprandial cholecystokinin release compared with participants with bulimia nervosa (t(76.44) = 2.51; P = .01) and did not differ significantly from controls (t(75.93) = 0.03; P = .98). Participants with purging disorder reported significantly greater postprandial fullness and gastrointestinal distress compared with participants with bulimia nervosa and controls.

CONCLUSIONS

Purging disorder is a clinically significant disorder of eating that appears to be distinct from bulimia nervosa on subjective and physiological responses to a test meal. Findings support further consideration of purging disorder for inclusion in the classification of eating disorders. Future studies on the psychobiology of purging disorder are needed to understand the propensity to purge in the absence of binge eating.

Obsessive-compulsive characteristics in women who have recovered from bulimia nervosa

OBJECTIVE

The goal of this study was to follow up on reports that obsessive-compulsive characteristics, which are commonly elevated in bulimia nervosa (BN), may also be elevated in individuals who have recovered from BN (BN-R).

METHOD

Self-ratings on the Maudsley Obsessional-Compulsive Inventory (MOCI), the Restraint Scale (a measure of dieting behavior related to weight concerns), and questionnaires reflecting eating disorder-related symptoms were evaluated for women who met criteria for BN (n = 25) or BN-R (n = 21) and were free of obsessive-compulsive disorder, and for healthy female controls (n = 28).

RESULTS

MOCI scores for the BN-R group (5.5 +/- 5.4) were similar to those for the BN group (5.4 +/- 4.4) and were significantly elevated (p < 0.05, p < 0.02, respectively) in comparison to controls (2.5 +/- 1.9). Of note, MOCI scores for the BN-R group were significantly correlated with scores on the Restraint Scale (r = 0.60, p < 0.02).

CONCLUSION

Further studies are needed to assess the relationship between elevated obsessive-compulsive characteristics and eating patterns in individuals recovered from BN.

Effects of type 1 diabetes on gray matter density as measured by voxel-based morphometry

The effects of type 1 diabetes and key metabolic variables on brain structure are not well understood. Sensitive methods of assessing brain structure, such as voxel-based morphometry (VBM), have not previously been used to investigate central nervous system changes in a diabetic population. Using VBM, we compared type 1 diabetic patients aged 25-40 years with disease duration of 15-25 years and minimal diabetes complications with an age-matched, nondiabetic control group. We investigated whether lower than expected gray matter densities were present, and if so, whether they were associated with glycemic control and history of severe hypoglycemic events. In comparison with control subjects, diabetic patients showed lower density of gray matter in several brain regions. Moreover, in the patient group, higher HbA(1c) levels and severe hypoglycemic events were associated with lower density of gray matter in brain regions responsible for language processing and memory. Our study represents the first comprehensive study of gray matter density changes in type 1 diabetes and suggests that persistent hyperglycemia and acute severe hypoglycemia have an impact on brain structure.

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.

Neuropeptides in eating disorders

The past decade has witnessed a dramatic acceleration in research on the role of the neuropeptides in the regulation of eating behavior and body weight homeostasis. This expanding research focus has been driven in part by increasing public health concerns related to obesity and the eating disorders anorexia nervosa (AN) and bulimia nervosa (BN). Preclinical advances have been facilitated by the development of new molecular and behavioral research methodologies. With a focus on clinical investigations in AN and BN, this article reviews research on selected hypothalamic and gut-related peptide systems with prominent effects on eating behavior. Studies of the orexigenic peptides neuropeptide Y and the opioid peptides have shown state-related abnormalities in patients with eating disorders. With respect to gut-related peptides, there appears to be substantial evidence for blunting in the meal-related release of the satiety promoting peptide cholecystokinin in BN. Fasting plasma levels of the orexigenic peptide ghrelin have been found to be elevated in patients with AN. As discussed in this review, additional studies will be needed to assess the role of nutritional and body weight changes in neuropeptide alterations observed in symptomatic eating disorder patients, and to identify stable trait-related abnormalities in neuropeptide regulation that persist in individuals who have recovered from an eating disorder.

Report of the National Institutes of Health workshop on overcoming barriers to treatment research in anorexia nervosa

OBJECTIVE

Anorexia nervosa (AN) is associated with serious medical morbidity and has the highest mortality rate of all psychiatric disorders. The National Institutes of Health (NIH) Workshop on Overcoming Barriers to Treatment Research in Anorexia Nervosa convened on September 26-27, 2002 to address the dearth of treatment research in this area. The goals of this workshop were to discuss the stages of illness and illness severity, pharmacologic interventions, psychological interventions, and methodologic considerations.

METHOD

The program consisted of a series of brief presentations by moderators, each followed by a discussion of the topic by workshop participants, facilitated by the session chair.

RESULTS

This report summarizes the major discussions of these sessions and concludes with a set of recommendations related to the development of treatment research in AN based on these findings.

DISCUSSION

It is crucial that treatment research in this area be prioritized.

Laboratory screening for electrolyte abnormalities and anemia in bulimia nervosa: a controlled study

OBJECTIVE

Abnormal eating patterns and recurrent purging behaviors can result in significant medical complications. The purpose of this study was to assess the frequency of abnormalities in clinical laboratory tests in patients with bulimia nervosa who reported being otherwise in good health.

METHODS

Subjects included nonhospitalized women (N = 74) who met criteria for bulimia nervosa outlined in the 3rd Rev. ed. of the Diagnostic and Statistical Manual of Mental Disorders. They also reported use of self-induced vomiting and/or laxatives as compensatory behaviors (purging subtype). The control group (N = 110) included female volunteers with no history of a psychiatric disorder. All subjects reported being in good medical health, were medication free, and were in a normal weight range. Blood samples were analyzed in the hospital clinical laboratory.

RESULTS

Compared with controls, patients showed more frequent occurrence of low values for serum potassium (6.8% vs. 0.9%; p <.05) and chloride (8.1% vs. 0.9%; p <.02). Electrolyte abnormalities occurred most often in patients with frequent bulimic episodes. Study groups did not differ significantly in frequency of abnormal hemoglobin concentrations.

DISCUSSION

These results help to clarify the expected frequency of electrolyte abnormalities in individuals with bulimia nervosa who report otherwise good medical health. The substantial frequency of hypokalemia and hypochloremia underscores the importance of an appropriate medical assessment for individuals with this disorder.

Dopamine and mania: behavioral and biochemical effects of the dopamine receptor blocker pimozide

Although recent data suggest that pimozide has effects at other neurotransmitter receptor sites, it is one of the more specific neuroleptics in its effects on dopamine receptors. We report that in manic patients pimozide produces substantial clinical improvement with a magnitude and time course similar to that observed with the more routinely used phenothiazines chlorpromazine and thioridazine. Pimozide did not significantly increase probenecid-induced accumulations of the dopamine metabolite homovanillic acid (HVA) compared to pretreatment values. Higher HVA values were observed in manic than in nonmanic patients, however. These clinical and biochemical data add to a growing body of indirect evidence that a dopaminergic alteration may be associated with some components of the manic syndrome.

Behavioral, biochemical and neuroendocrine responses to amphetamine in normal twins and 'well-state' bipolar patients

An i.v. injection of dextroamphetamine (0.3 mgm/kg) was given to 13 pairs of normal monozygotic twins, three pairs of normal dizygotic twins and 11 patients with bipolar affective disorder in remission and off medications. Behavioral excitation in response to amphetamine was highly correlated in monozygotic twins; it was predicted by the baseline variables of high plasma MHPG, low serum prolactin and low pulse; it correlated with a rise in cortisol; and it was not correlated with plasma amphetamine level. Pre-infusion baseline MHPG and growth hormone and prolactin responses to amphetamine also were concordant in twins. Plasma amphetamine level, pulse and blood pressure and cortisol responses were not concordant, suggesting significant environmental influences. Haloperidol pretreatment in one pair of twins abolished the excitation response but did not reduce increases in cortisol and growth hormone. This suggests a role for dopamine in the excitation response but predominant serotonergic and noradrenergic mediation of the hormonal responses. None of the responses or baseline measures distinguished patients from controls. Thus, no consistently altered sensitivity to monoaminergic stimulation by amphetamine in bipolar affective disorder was demonstrated in this study. This is one of the first reports of familial (possibly genetic) variation in a psychostimulant drug response in man. The responses identified as concordant may be useful in characterizing other pathologic conditions.

Decreased serum leptin in bulimia nervosa

The eating disorder bulimia nervosa has been associated with impaired satiety, decreased resting metabolic rate, and abnormal neuroendocrine regulation. Preclinical studies suggest that such alterations could be associated with impaired leptin function. Thus, the goal of this study was to assess whether leptin function is decreased in bulimia nervosa. Serum leptin levels measured in women with bulimia nervosa (n = 18) and in women who had maintained stable recovery from bulimia nervosa (n = 15) were compared with values in healthy female controls (n = 20). Subjects were studied during the follicular phase of their menstrual cycle after an overnight fast and bed rest. Baseline serum samples were analyzed for leptin concentration by RIA. Subject groups were matched for age and body weight. Analysis of covariance, adjusting for percent body fat, demonstrated abnormally low serum leptin levels in the bulimia nervosa group (P: = 0.02), with a trend toward an inverse correlation between frequency of binge episodes and serum leptin concentration (P: < 0.1). Additionally, the remitted patient group demonstrated abnormally low leptin values (P: = 0.01). These results are consistent with the hypothesis that decreased leptin function may be associated with alterations in eating patterns, metabolic rate, and neuroendocrine regulation in bulimia nervosa.

Serotonin function following remission from bulimia nervosa

Abnormal serotonergic regulation in bulimia nervosa is thought to contribute to recurrent binge eating, depressed mood, and impulsivity. To follow-up on previous studies showing decreased neuroendocrine responses in symptomatic patients, this study assessed serotonin-mediated prolactin responses in individuals who had remitted from bulimia nervosa. Subjects included 21 women with a history of bulimia nervosa and 21 healthy female controls, as well as an additional comparison group of 19 women with current bulimia nervosa. Placebo-controlled neuroendocrine response studies utilized a single oral dose (60 mg) of the indirect serotonin agonist d,l-fenfluramine. For the bulimia nervosa remitted group, the fenfluramine-stimulated elevation in serum prolactin concentration was not significantly different from the response in healthy controls, but was significantly larger than the response in patients with current bulimia nervosa (p < .01). These findings suggest that diminished serotonergic neuroendocrine responsiveness in bulimia nervosa reflects a state-related abnormality. The results are discussed in relationship to recent reports indicating that some alterations in central nervous system serotonin regulation may persist in symptomatically recovered individuals.

Salivary gland enlargement and elevated serum amylase in bulimia nervosa

BACKGROUND

Clinical reports have described salivary gland enlargement in bulimia nervosa, particularly in patients with elevated serum amylase concentration. The goal of the current study was to provide a controlled comparison of salivary gland size in patients with bulimia nervosa and healthy volunteers.

METHODS

Subjects included 17 women with bulimia nervosa and 21 healthy female control subjects. Dimensions of the parotid and submandibular salivary glands were estimated by ultrasonography. Blood samples for amylase measurement were obtained after overnight fast.

RESULTS

Parotid gland size was enlarged 36% in patients with bulimia nervosa in comparison to control subjects (p < .01). For the patient group, salivary gland size was significantly correlated with frequency of bulimic symptoms and with serum amylase concentration.

CONCLUSIONS

These results provide new quantitative data demonstrating increased salivary gland size in bulimia nervosa. Further studies are needed to evaluate factors responsible for salivary gland enlargement and hyperamylasemia in this disorder.

Research update on serotonin function in bulimia nervosa and anorexia nervosa

The extent to which dysregulation of serotonin function in the central nervous system may contribute to core symptoms in patients with bulimia nervosa and anorexia nervosa is currently an area of intensive psychobiological investigation. Preclinical and clinical studies have demonstrated the involvement of the neurotransmitter serotonin in the regulation of food intake, suggesting that impaired serotonin-mediated satiety signals could contribute to patterns of recurrent binge eating. Other symptom patterns in patients with eating disorders, including mood dysregulation, impulsivity, and obsessionality, as well as therapeutic response to serotonergic agents, suggest involvement of serotonergic pathways. With a primary focus on serotonin function, this article reviews clinical studies of neuroendocrine and behavioral response to pharmacological challenges, levels of neurotransmitter metabolite in cerebrospinal fluid, and platelet studies. Controlled clinical trials involving pharmacological treatment with serotonergic medications are summarized. Considerations for future research are discussed.

Effects of suppressing thoughts about body weight: a comparison of dieters and nondieters

OBJECTIVE

Experimental suppression of a neutral target thought often results in a subsequent "rebound" in the frequency of the thought. In this study, we tested the hypothesis that suppression of weight-related thoughts contributes to body weight preoccupations characteristic of dieters.

METHOD

Subjects included 19 female dieters and 21 female nondieters. Following a randomized design, subjects were asked either to suppress (experimental condition) or express (control condition) the thought of weighing themselves.

RESULTS

Nondieters demonstrated a significant rebound in frequency of the target thought following suppression (p < .05). Dieters expressed weight-related thoughts more frequently than nondieters, but did not show a rebound following target thought suppression.

DISCUSSION

Thought suppression may foster development of weight-related preoccupations whereas the role suppression plays in the maintenance of dieters' weight-related preoccupations remains unclear.

Decreased serotonin function in bulimia nervosa

BACKGROUND

Evidence that serotonin-active antidepressant medications decrease binge eating in patients with bulimia nervosa has fueled interest in the hypothesis that abnormal serotonergic neurotransmitter function contributes to symptoms of the disorder. To evaluate this hypothesis, we employed pharmacological challenge testing to compare serotonin function in patients with bulimia nervosa and healthy controls.

METHODS

Neuroendocrine response patterns were compared for 15 nonhospitalized, medication-free, normal-weight women with bulimia nervosa and 14 age-matched healthy female controls. Behavioral assessment included ratings of eating disorder symptoms, depression, and anxiety. Serotonergic response patterns were assessed by measuring the increase in serum prolactin concentration during 5 hours following single-dose, oral administration of 60 mg of d,l-fenfluramine hydrochloride (Pondimin).

RESULTS

For patients with bulimia nervosa, the fenfluramine-stimulated increase in serum prolactin concentration was significantly less than for controls. Within the patient group, the frequency of binge eating episodes during the 4 weeks prior to the study exhibited a significant inverse correlation with serotonin-stimulated prolactin secretion.

CONCLUSION

Our study provides new evidence that impaired central nervous system serotonergic responsiveness may contribute to the onset or maintenance of abnormal eating patterns in patients with bulimia nervosa.

Cerebrospinal fluid leptin in anorexia nervosa: correlation with nutritional status and potential role in resistance to weight gain

Studies in rodents have shown that leptin acts in the central nervous system to modulate food intake and energy metabolism. To evaluate the possible role of leptin in the weight loss of anorexia nervosa, this study compared cerebrospinal fluid (CSF) and plasma leptin concentrations in anorexic patients and controls. Subjects included 11 female patients with anorexia nervosa studied at low weight and after treatment, and 15 healthy female controls. Concentrations of leptin in blood and CSF were measured by RIA. Patients with anorexia nervosa, compared to controls, had decreased concentrations of leptin in CSF (98 +/- 26 vs. 160 +/- 58 pg/mL; P < 0.0005) and plasma (1.75 +/- 0.46 vs. 7.01 +/- 3.92 ng/mL; P < 0.005). The CSF to plasma leptin ratio, however, was higher for patients (0.060 +/- 0.023) than for controls (0.025 +/- 0.007; P < 0.0001). At posttreatment testing, although patients had not yet reached normal body weight, CSF and plasma leptin concentrations had increased to normal levels. These results demonstrate the dynamic changes in plasma and CSF leptin during positive energy balance in anorexia nervosa. The results further suggest that normalization of CSF leptin levels before full weight restoration during treatment of anorexic patients could contribute to resistance to weight gain and/or incomplete weight recovery.

Medications in the treatment of eating disorders

Effective planning for medication treatment in patients with bulimia nervosa and anorexia nervosa is based on a comprehensive clinical assessment, including a careful review of comorbid psychiatric disorders and response to treatments for previous episodes of the disorder. Although most patients with bulimia nervosa are offered a trial of psychotherapy, significant results of controlled trials have contributed to an increased role for medications in the treatment of patients with this disorder. Pharmacologic treatment of anorexia nervosa has similarities to that of treatment-resistant depression, with the clinician turning to open trials and clinical reports for clues to rational management. As described in this article, considerations of potential side effects and medical complications are likely to play an important role in guiding the choice of medication used for treatment of patients with eating disorders.

Studies of serotonin function in anorexia nervosa

Neuroendocrine, temperature, test-meal, and psychometric responses are reviewed following challenges with the post-synaptic 5-HT receptor agonist m-chlorophenylpiperazine (m-CPP), the 5-HT precursor L-tryptophan (L-TRP), and placebo in 12 patients with anorexia nervosa (AN) and 16 healthy controls. A subset of the AN patients (n = 8) were rechallenged 3-4 weeks after attaining a predetermined goal weight. AN patients had blunted prolactin (PRL) responses to both m-CPP and L-TRP at low-weight and at goal-weight in comparison to controls, although there was a tendency toward normalization with weight gain. There were trends for blunted growth hormone (GH) responses following both L-TRP and m-CPP in the low-weight but not the goal-weight AN patients. Cortisol (CORT) responses following m-CPP and L-TRP were not significantly different among any of the groups. Temperature and test-meal measures were largely unaffected by serotonergic agents in the patients, although m-CPP decreased meal size in the controls. Psychometric responses were variable and are briefly described. Taken together, these findings indicate that responsiveness in post-synaptic hypothalamic-pituitary serotonergic pathways is altered in AN patients. Although there were some trends toward normalization of responsiveness following goal-weight attainment, many differences tended to persist in the patients despite an average increase of 13 kilograms. These may represent changes in serotonergic function at levels in the CNS "above" the hypothalamus.

Comparison of the effects of amino acid mixture and placebo on plasma tryptophan to large neutral amino acid ratio

To assess the possible role of altered central serotonin function in psychiatric disorders, investigators have utilized pharmacological challenge testing with an amino acid mixture to decrease blood tryptophan concentration and, indirectly, brain serotonin levels. The aim of this pilot study was to assess the effectiveness of a modified amino mixture, administered in capsule form, in decreasing plasma tryptophan levels. Studies were conducted in six healthy, medication-free female volunteers. Following double-blind, randomized, cross-over design, subjects received on separate days capsules containing a tryptophan-free amino acid mixture (31.5 grams) or lactose placebo. Over the six hours following amino acid administration, plasma tryptophan concentrations decreased to 21% of baseline values, while the tryptophan/large neutral amino acid ratio decreased to 6% of baseline. Subjects reported minimal symptoms of nausea or other side effects following amino acid administration. The results suggest that the modified amino acid mixture may be useful in assessing behavioral responses to acute tryptophan depletion challenge testing.

Elevated sweet taste pleasantness ratings in bulimia nervosa

Recent studies suggest that some patients with bulimia nervosa may experience elevated pleasantness responses to sweet taste. This study explored possible associations between symptoms patterns and pleasantness ratings for sucrose solutions in bulimic patients. Subjects included 15 women meeting DSM III-R criteria for narrowly defined bulimia nervosa (no history of other eating disorder); five patients with current bulimia nervosa and a past history of anorexia nervosa; and 20 healthy age-matched female controls. Subjects ate a standardized breakfast prior to the morning study visit. Sucrose-water solutions (0% to 40% sucrose) were rated for sweetness intensity and pleasantness. Patients with narrowly defined bulimia nervosa showed significantly higher pleasantness ratings for 40% sucrose solutions than controls and patients with a history of anorexia nervosa. Pleasantness ratings were not significantly correlated with frequency of binge eating or purging behaviors. These results extend previous evidence for altered sweet taste pleasantness responses in bulimia nervosa, and for differences in eating-related behaviors between patients with narrowly defined bulimia nervosa vs. those with past anorexia nervosa.

Resting metabolic rate of anorexia nervosa patients during weight gain

To determine whether changes in energy metabolism may contribute to the difficulty of weight gain observed in anorexic patients, resting metabolic rate (RMR) and neuroendocrine function were studied in 10 patients diagnosed with anorexia nervosa. RMR per kilogram lean body mass (+/- SEM) was not significantly different from that of healthy volunteers on admission (95.9 +/- 5.6 vs 103.6 +/- 3.3 kJ/kg, respectively), during early refeeding (108.6 +/- 6.9 kJ/kg), or at target weight (102.1 +/- 3.8 kJ/kg). At late refeeding RMR was significantly higher (132.1 +/- 4.9 kJ/kg, P < 0.0001). There were no significant correlations between plasma norepinephrine and thyroid hormones and RMR. The rise in RMR during refeeding is at least double that observed in other studies in which normal-weight subjects are experimentally overfed or experimentally underfed and then refed. These results suggest that the increase in RMR during refeeding is disproportionate to weight gain and this large magnitude of increase may be unique to anorexia nervosa.

Hypnotizability, dissociation, and bulimia nervosa

This study examined the levels of hypnotizability and dissociation in an outpatient sample of 17 normal-weight bulimic women and 20 healthy controls. Bulimic patients were significantly more hypnotizable than controls (p < .003) and scored higher on a self-report scale of dissociative experiences (p < .02). The results of measures of hypnotizability and dissociation showed a significant positive correlation in the combined subject group. These results are consistent with previous reports on hospitalized patients and college students and suggest that psychological factors associated with hypnotizability might play a role in the etiology and treatment of bulimia nervosa.

Hypnotizability, dissociation, and bulimia nervosa

This study examined the levels of hypnotizability and dissociation in an outpatient sample of 17 normal-weight bulimic women and 20 healthy controls. Bulimic patients were significantly more hypnotizable than controls (p < .003) and scored higher on a self-report scale of dissociative experiences (p < .02). The results of measures of hypnotizability and dissociation showed a significant positive correlation in the combined subject group. These results are consistent with previous reports on hospitalized patients and college students and suggest that psychological factors associated with hypnotizability might play a role in the etiology and treatment of bulimia nervosa.

Testmeal responses following m-chlorophenylpiperazine and L-tryptophan in bulimics and controls

A wealth of data support a role for serotonin (5-HT) function in the mediation of satiety responses, that are impaired in patients with bulimia nervosa. Testmeal results are presented in which 26 bulimic patients and 17 normal controls were given in randomized, double-blind-fashion, placebo, and the 5-HT agents m-chlorophenylpiperazine (m-CPP, 0.5 mg/kg p.o.) and L-tryptophan (L-TRP, 100 mg/kg i.v.). Three and one-half hours after drug administration, subjects were allowed to eat and lib from a standardized testmeal of 3,500 calories, after which postprandial vomiting was not allowed. M-CPP, but not L-TRP, significantly decreased meal size in the combined group, the controls, and to a lesser extent, the bulimics (P < or = .06). Maximum m-CPP concentrations were inversely correlated to the number of calories consumed in the total group. Following m-CPP, there were significant decreases in carbohydrate, protein, and fat intake in the total group of subjects. There were also trends for decreased carbohydrate and protein intake in the bulimics following m-CPP. There were trends for both m-CPP and L-TRP to reduce fat intake in the controls. Differences in the effects between m-CPP and L-TRP are likely due to differential involvement of 5-HT receptor subtypes at presynaptic and postsynaptic sites. These studies in humans confirm reports in animals that m-CPP decreases food intake, including carbohydrates, protein, and fat in a mixed testmeal.

Impulsivity ratings in bulimia nervosa: relationship to binge eating behaviors

Although impulsive behavioral patterns are often described by patients with bulimia nervosa, there has been little formal evaluation of the relationship between impulsivity and eating-related symptomatology in this disorder. In this controlled outpatient study, ratings on the Barratt Impulsivity Scale were significantly elevated in 20 women with bulimia nervosa in comparison to 20 healthy female volunteers. Frequency of binge eating episodes was not significantly correlated with impulsivity ratings. Although these results indicate increased prevalence of impulsive behavioral style in patients with bulimia nervosa, impulsivity per se does not appear to be a predictor of symptom severity as reflected in frequency of bulimic episodes.

Concentrations of adipsin in blood and rates of adipsin secretion by adipose tissue in humans with normal, elevated and diminished adipose tissue mass

Adipsin, which is identical to complement factor D, is synthesized by fat cells, circulates in the bloodstream and is profoundly deficient in mice with genetic and hypothalamic obesity. With the recent cloning of human adipsin, a quantitative human immunoassay has been developed. In the present study, we measured adipsin blood concentrations in humans with increased and decreased adipose stores as well as adipsin secretion by adipose tissue obtained from lean and obese individuals. The results demonstrate that adipsin is released by human adipose tissue fragments as has previously been shown in mice, and that, in contrast to obese mice, blood adipsin concentrations were not reduced in the obese humans tested in this study. We also observed that blood adipsin concentrations can vary as a function of feeding or adiposity, in that they tend to be mildly elevated in obese individuals or mildly reduced in individuals with total lipo-atrophy, cachexia related to AIDS and anorexia nervosa. Thus, the circulating concentration of adipsin tends to correlate positively with degree of adiposity. Clearly, no deficiency in blood adipsin concentrations or adipsin secretion by adipose tissue was observed in the obese individuals studied.

Alexithymia ratings in bulimia nervosa: clinical correlates

Previous reports indicate that some patients with eating disorders have alexithymic characteristics, including affect deficit states and paucity of imagination. This study evaluated whether nonhospitalized patients with bulimia nervosa had elevated ratings of alexithymia in comparison to age-matched controls, and whether severity of bulimic symptoms was correlated with elevations in alexithymia ratings. Because alexithymia may be secondary to concurrent depression, this study was limited to patients with bulimia nervosa who were free of major depression. The authors compared alexithymia ratings for nonhospitalized normal weight women meeting DSM-III-R criteria for bulimia nervosa (N = 20) to healthy female volunteers (N = 20), utilizing the Toronto Alexithymia Scale (TAS) as the primary assessment instrument. Subjects also completed standardized rating scales for bulimic symptoms, depression, and anxiety. Alexithymia rating scale scores were significantly higher for patients with bulimia nervosa than for controls. In comparison to controls, patients had significant elevations on TAS factors reflecting affect deficit states, but normal scores for factors reflecting imagination and abstract thinking. Frequency of binge eating or purging behaviors was not correlated with alexithymia ratings. These data indicate that some patients with bulimia nervosa have alexithymic characteristics. Affect dysregulation was more prominent than limitation in fantasy or metaphorical thought. Additional studies are needed to assess whether presence of alexithymic characteristics may be predictive of response to treatment in patients with bulimia nervosa.

Cerebrospinal fluid TRH immunoreactivity in anorexia nervosa

Central nervous system (CNS) thyrotropin-releasing hormone (TRH) activity is of interest in patients with anorexia nervosa. First, anorexics have peripheral thyroid abnormalities that appear to be related to weight and nutritional status. Second, CNS TRH activity may effect many other physiologic systems that are known to be disturbed in patients with anorexia nervosa. We found that anorexic patients, when both underweight and studied after attaining goal weight, had significantly reduced CSF TRH concentrations in comparison to controls. These data suggest that weight gain or increased caloric intake, in contrast to its large effect on peripheral thyroid function, has relatively little effect on CNS TRH activity. The reason for reduced CSF TRH in goal weight anorexics is not known but could be trait related, a persistent defect slow to normalize after weight gain, or related to these patients still being at a weight lower than controls. Finally, in terms of CSF TRH concentrations, this study suggests that anorexia nervosa has a different pathophysiology than major depressive disorder.

Pharmacologic approaches in the treatment of eating disorders

Important advances in the treatment of eating disorders, particularly bulimia nervosa, have been made during the past decade. Controlled trials for bulimia nervosa have demonstrated significant benefit from short-term pharmacotherapy with antidepressant medications and from short-term individual and group psychotherapies. Despite these advances, treatment of a patient often involves complex clinical decisions around such issues as choice of initial treatment modality, incomplete resolution of symptoms, and the role of long-term maintenance treatment. To address these questions, this review focuses primarily on summarizing results of published controlled trials of pharmacotherapy in patients with bulimia nervosa. In addition, it outlines the more limited literature on controlled pharmacotherapy trials for anorexia nervosa and for the provisionally identified syndrome of binge eating disorder.

Neuroendocrine responses to m-chlorophenylpiperazine and L-tryptophan in bulimia

Preclinical and clinical evidence supports a theory of serotonin (5-hydroxytryptamine [5-HT]) dysregulation in bulimia. We therefore studied the prolactin (PRL) and cortisol responses following challenges with the postsynaptic 5-HT receptor agonist m-chlorophenylpiperazine (m-CPP), 0.5 mg/kg orally, the 5-HT precursor L-tryptophan, 100 mg/kg intravenously, and placebo in a group of 28 normal weight bulimic patients and 16 healthy controls. Patients with bulimia, regardless of the presence of major depression, had significantly blunted PRL responses following m-CPP administration compared with those in controls. In contrast, only bulimic patients with concurrent major depression had significantly blunted PRL responses following L-tryptophan administration compared with those in nondepressed bulimic patients and controls. Cortisol responses following m-CPP were not significantly different for bulimic patients vs controls, although there was a trend toward blunted cortisol responses following L-tryptophan administration in the depressed bulimic patients. These differences in neuroendocrine responses were not related to differences in age, percent of average body weight, medications, time of day, peak plasma drug levels, or baseline estradiol levels. Seasonal variations in PRL responses to both agents were identified, although covariation for season did not alter the group differences. The PRL responses following m-CPP administration were inversely correlated to baseline cortisol levels in the bulimic patients, but not in the controls, suggesting a dampening effect by hypothalamic-pituitary-adrenal axis dysfunction on postsynaptic 5-HT receptor sensitivity. The reasons for the differing hormonal responses to these two serotonergic agents may relate to differential involvement of presynaptic and postsynaptic mechanisms, 5-HT receptor subtypes, and anatomical loci of action. The blunted PRL responses to m-CPP administration suggest that postsynaptic 5-HT receptor sensitivity is altered in bulimia nervosa, and that similar alterations in 5-HT receptors at or above the level of the hypothalamus may contribute to binge eating and other behavioral symptoms.

Headache responses following m-chlorophenylpiperazine in bulimics and controls

We have previously reported that the serotonin (5-HT) agonist meta-chlorophenylpiperazine (m-CPP) induced late occurring migraine-like headaches in a group of patients with eating disorders and controls (n = 52). In this report, we extend our analyses of these data and describe results indicating that headache responses following m-CPP are greater in patients with bulimia nervosa than controls, regardless of the presence of anorexia nervosa or major depression. Although patients with severe migraine-like headaches had higher peak m-CPP levels than patients without severe headaches, these levels are not higher than other groups studied who did not get headaches. These findings suggest that post-synaptic 5-HT receptor sensitivity is altered in the vascular tissues of bulimic patients. Additional disturbances in 5-HT function, perhaps presynaptic ones, may be associated with anorexia nervosa and major depression. Similar alterations in other 5-HT pathways at or above the level of the hypothalamus may contribute to binge eating and other behavioral symptoms of bulimia nervosa. Further studies exploring the functional integrity of 5-HT receptors and their subtypes are warranted in bulimic patients, as well as in patients with nonbulimic anorexia nervosa, minor and major depression without an eating disorder, and migraine and other headache patients.

Low serotonin and dopamine metabolite concentrations in cerebrospinal fluid from bulimic patients with frequent binge episodes

Cerebrospinal fluid neurotransmitter metabolite levels were studied to assess whether measures of central serotonin, dopamine, or norepinephrine function are associated with severity of abnormal eating patterns in patients with bulimia nervosa. In comparison with healthy controls (N = 17), hospitalized bulimic patients with a history of binge eating more frequently than twice daily (N = 11) had significantly lower CSF concentrations of 5-hydroxyindoleacetic acid and homovanillic acid. For the total patient group (N = 29), levels of both metabolites were significantly inversely correlated with binge frequency. On the basis of preclinical studies, these results were examined in the context of speculative models in which low central serotonin function might contribute to blunted satiety responses in bulimic patients, while low central dopamine activity might play a role in abnormal hedonic responses to food.

Pharmacotherapy of depression in the medically ill: directions for future research

A common problem facing the psychiatric consultant and the medical practitioner is evaluating depression in patients with concurrent medical illnesses. Depression is difficult to recognize in the medically ill, often presenting with "masked" symptoms and organized into unique syndromes. A primary concern of the clinician is identifying those patients who are likely to benefit from an antidepressant trial. Although antidepressants have been shown to sometimes be of benefit in medical populations, the symptoms predicting antidepressant response remain poorly defined. Important directions for future research include 1) evaluating the safety and efficacy of newer antidepressants in the medically ill and 2) identifying those depressive syndromes that may be responsive to pharmacotherapy.

Reduced resting metabolic rate in patients with bulimia nervosa

To determine whether there was a metabolic basis for recent reports that bulimic patients had low energy requirements for weight maintenance, energy expenditure measurements were made in 15 women with bulimia nervosa during abstinence from bingeing and vomiting. Resting metabolic rate, adjusted for differences in lean body mass, was significantly lower in bulimics (mean +/- SE, 4201 +/- 126 kJ/d) than healthy volunteers (4694 +/- 172 kJ/d). Bulimic patients had a blunted increase in oxygen consumption in response to low and moderate levels of exercise (421 +/- 16 and 689 +/- 17 mL/min) compared with values for healthy volunteers (491 +/- 28 and 795 +/- 26 mL/min). Plasma triiodothyronine (1.1 +/- 0.07 vs 1.4 +/- 0.08 nmol/L) levels, plasma norepinephrine levels in supine (0.58 +/- 0.04 vs 1.06 +/-0.17 nmol/L) and standing (1.34 +/- 0.15 vs 2.46 +/- 0.30 nmol/L) subjects, and the increase in norepinephrine levels during orthostatic challenge (0.76 +/- 0.15 vs 1.40 +/- 0.25 nmol/L) all were significantly less in bulimics than volunteers. These results are consistent with previous reports of decreased energy requirements for weight maintenance and decreased plasma levels of metabolism-related hormones in patients with bulimia. However, the effects of reduced energy intake in metabolic studies of patients with bulimia need to be further investigated.

The effects of carbamazepine on resting metabolic rate and thyroid function in depressed patients

Resting metabolic rate and thyroid hormone levels were studied in 11 patients with affective disorders before and during treatment with carbamazepine (CBZ). CBZ has been previously reported to reduce thyroid hormones, but the metabolic consequence of this effect has not been explored. During CBZ treatment, thyroid hormones decreased significantly (T4, 7.53 versus 5.74 micrograms/dl, p less than 0.001), whereas the resting metabolic rate (RMR) did not (31.6 versus 30.7 kcal/m2/hr). Baseline RMRs were low and the expected positive relationship between RMR and weight was disrupted in females. The extent of previous exposure to tricyclic and monoamine oxidase inhibitors antidepressant treatment was significantly associated with lower baseline RMRs. We conclude that CBZ has no significant effect on RMR despite robust decreases in thyroid function.

Measurement of CSF dynorphin A 1-8 immunoreactivity in anorexia nervosa and normal-weight bulimia

Twenty-one patients with anorexia nervosa and 35 normal-weight patients with bulimia underwent a series of CSF studies involving measurement of CSF dynorphin A 1-8 immunoreactivity during hospitalization in an eating-disorder treatment and research program. The control group consisted of 17 healthy volunteers. There were no statistically significant differences in CSF dynorphin A 1-8 measurements among groups or within a group at various stages of treatment. These results regarding dynorphin A 1-8 immunoreactivity are discussed in light of other evidence for altered opiate function in some eating-disorder patients.

Serotonin in human eating disorders

The onset and progression of symptomatology in patients with anorexia nervosa and bulimia nervosa is complex. It is unlikely that dysregulation of a single neurotransmitter system would be sufficient to explain the pathophysiology of these disorders. The studies reviewed above provide preliminary evidence that decreased central serotonin function may contribute to the onset or persistence of binge eating episodes in patients with bulimia nervosa, including low weight anorexic patients with bulimic symptoms. Future clinical studies will benefit from the availability of selective serotonin receptor agonists and antagonists. Longitudinal studies through progressive phases of treatment and clinical remission will be important to clarify the contribution of dietary and body weight changes to results of neurotransmitter studies with eating disorder patients.

Eating disorders and depression: is there a serotonin connection?

Central serotonin pathways modulate eating patterns, and may also participate in the regulation of behavioral impulsivity and mood. Recent studies lend support to the hypothesis that impaired postingestive satiety in bulimia nervosa is associated with reduced hypothalamic serotonergic responsiveness. Serotonin dysregulation has been implicated in major depression, and may play a role in the increased prevalence of depressive episodes in patients with eating disorders. This review compares evidence for alterations in central serotonin regulation in patients with anorexia nervosa, bulimia nervosa, and depression. It is proposed that impaired synaptic transmission in functionally distinct serotonin pathways may result in concurrent or sequential periods of binge eating, behavioral impulsivity, and depression in patients with eating disorders.