Altered response to meta-chlorophenylpiperazine in anorexia nervosa: support for a persistent alteration of serotonin activity after short-term weight restoration

Acute Stress Exposure Alters Food-Related Brain Monoaminergic Profiles in a Rat Model of Anorexia

BACKGROUND

Adverse life experiences are a major risk factor for anorexia nervosa (AN). Eating-provoked anxiousness associated with AN is postulated to be due to food-related exaggerated serotonin activity in the brain and imbalances of monoamine neurotransmitters.

OBJECTIVES

Using a rodent model of stress-induced hypophagia, we investigated if stress exposure augments food-related serotonin turnover and imbalances in measures of brain serotonin and dopamine activity in manners consistent with anxiousness toward food and restricted eating.

METHODS

Adult male F344 rats were conditioned to associate an audio cue with daily food over 2 weeks, after which half of the rats were exposed to a single episode of tail shocks (stress) or left undisturbed (nonstressed). All rats were killed 48 h later, during a control period, the food-associated cue, or a period of food access. Serotonin, dopamine, and norepinephrine, as well as metabolite concentrations, were assessed across brain regions comprising reward, emotion, and feeding circuits relevant to AN in acutely stressed and nonstressed rats using HPLC. Statistical significance level was 5%.

RESULTS

Stress-induced rat hypophagia paralleled an augmented serotonin turnover in response to the food-associated cue in the hypothalamus and hippocampus, as well as food access in the hypothalamus and cortical areas (all P < 0.05). Stress exposure increased the ratio of serotonin to dopamine metabolites across several brain areas, but the magnitude of this imbalance was further augmented during the food-associated cue and food access in the brainstem, hippocampus, and cortical areas (all P < 0.05). Finally, stress lowered norepinephrine concentrations by 18% in the hypothalamus (P < 0.05).

CONCLUSIONS

The observed stress-induced changes to monoamine profiles in rats could have key implications for physiological states that contribute to restricted eating and may hold relevance for the development of AN precipitated by adverse life experiences.

Exploring the Eating Disorder Examination Questionnaire, Clinical Impairment Assessment, and Autism Quotient to Identify Eating Disorder Vulnerability: A Cluster Analysis

Eating disorders are very complicated and many factors play a role in their manifestation. Furthermore, due to the variability in diagnosis and symptoms, treatment for an eating disorder is unique to the individual. As a result, there are numerous assessment tools available, which range from brief survey questionnaires to in-depth interviews conducted by a professional. One of the many benefits to using machine learning is that it offers new insight into datasets that researchers may not previously have, particularly when compared to traditional statistical methods. The aim of this paper was to employ k-means clustering to explore the Eating Disorder Examination Questionnaire, Clinical Impairment Assessment, and Autism Quotient scores. The goal is to identify prevalent cluster topologies in the data, using the truth data as a means to validate identified groupings. Our results show that a model with k = 2 performs the best and clustered the dataset in the most appropriate way. This matches our truth data group labels, and we calculated our model’s accuracy at 78.125%, so we know that our model is working well. We see that the Eating Disorder Examination Questionnaire (EDE-Q) and Clinical Impairment Assessment (CIA) scores are, in fact, important discriminators of eating disorder behavior.

On the role of sadness in the psychopathology of anorexia nervosa

Recent models on the development and maintenance of eating disorders propose negative emotions to be important precursors for the occurrence of eating disorder symptomatology. In fact, previous research on bulimia nervosa (BN) and binge eating disorder provides evidence that negative emotions are an antecedent condition for binge eating. However, there is a lack of research examining the influence of negative emotions on restrictive eating and exercising in individuals with anorexia nervosa (AN). In an experimental study, women with AN (n=39) and BN (n=34) as well as a non-eating disordered control group (CG; n=34) watched a sadness-inducing film clip. Before and after the film clip participants rated their current desire to engage in dietary restriction (DTR) and desire to exercise (DTE). Main results reveal that DTR significantly increased after the film clip in women with AN only, while DTE decreased over time in all groups. Results are in line with the notion that negative emotions have a prominent influence on the core eating pathology in AN.

Interaction between serotonin transporter and dopamine D2/D3 receptor radioligand measures is associated with harm avoidant symptoms in anorexia and bulimia nervosa

Individuals with anorexia nervosa (AN) and bulimia nervosa (BN) have alterations of measures of serotonin (5-HT) and dopamine (DA) function, which persist after long-term recovery and are associated with elevated harm avoidance (HA), a measure of anxiety and behavioral inhibition. Based on theories that 5-HT is an aversive motivational system that may oppose a DA-related appetitive system, we explored interactions of positron emission tomography (PET) radioligand measures that reflect portions of these systems. Twenty-seven individuals recovered (REC) from eating disorders (EDs) (7 AN-BN, 11 AN, 9 BN) and nine control women (CW) were analyzed for correlations between [(11)C]McN5652 and [(11)C]raclopride binding. There was a significant positive correlation between [(11)C]McN5652 binding potential (BP(non displaceable(ND))) and [(11)C]Raclopride BP(ND) for the dorsal caudate, antero-ventral striatum (AVS), middle caudate, and ventral and dorsal putamen. No significant correlations were found in CW. [(11)C]Raclopride BP(ND), but not [(11)C]McN5652 BP(ND), was significantly related to HA in REC EDs. A linear regression analysis showed that the interaction between [(11)C]McN5652 BP(ND) and [(11)C]raclopride BP(ND) in the dorsal putamen significantly predicted HA. This is the first study using PET and the radioligands [(11)C]McN5652 and [(11)C]raclopride to show a direct relationship between 5-HT transporter and striatal DA D2/D3 receptor binding in humans, supporting the possibility that 5-HT and DA interactions contribute to HA behaviors in EDs.

Current status of functional imaging in eating disorders

Eating Disorders are complex psychiatric problems that involve biologic and psychological factors. Brain imaging studies provide insights about how functionally connected brain networks may contribute to disturbed eating behavior, resulting in food refusal and altered body weight, but also body preoccupations and heightened anxiety. In this article, we review the current state of brain imaging in eating disorders, and how such techniques may help identify pathways that could be important in the treatment of those often detrimental disorders.

Association between serotonin transporter gene polymorphism and eating disorders outcome: a 6-year follow-up study

Eating disorder patients show different long-term outcomes, and trait-related alterations of serotonergic function, which might be related with the serotonin transporter (5-HTT) gene. We studied the relationships between 5-HTTLPR polymorphism, eating specific and general psychopathology and the long-term outcome of anorexia nervosa (AN) and bulimia nervosa (BN) patients. We evaluated the distribution of the functional 5-HTTLPR polymorphism in a series of 201 Italian, Caucasian, eating disorder patients (113 with AN and 88 with BN binge/purging (BP subtype) and in 150 Caucasian unrelated controls. Prior to starting an individual cognitive behavior therapy, a clinical assessment was performed by means of the structured clinical interview for DSM-IV axis I disorders and several self-report questionnaires. This assessment was repeated at the end of treatment, 3 years after the end of treatment and 3 years after the first follow-up. Diagnostic changes between AN and BN were frequent (28.3%), and the presence of depressive disorders was associated with a higher rate of diagnostic crossover during the follow-up period. The S-allele of the 5-HTTLPR genotype increases the risk susceptibility for both depressive comorbidity (OR = 4.23; 95% CI, 1.45-12.37) and diagnostic crossover during the follow-up period in AN patients (OR = 5.04; 95% CI, 1.69-14.98). Logistic regression analyses confirmed these findings, when the interaction between genotype and psychiatric comorbidity as predictors of diagnostic instability in AN patients were taken into account. No significant association was found between 5-HTTLPR genotype and recovery. The S-allele of the 5-HTTLPR genotype increases the risk for depressive disorders comorbidity, and moderates the long-term outcome of anorectic patients.

Evidence of complex involvement of serotonergic genes with restrictive and binge purge subtypes of anorexia nervosa

OBJECTIVES

There is mixed evidence of association of serotoninergic genes with anorexia nervosa (AN), but substantial evidence for the involvement of serotonergic mechanisms in appetite control. This study was designed to investigate possible associations between the two subtypes of AN (Restricting-RAN, and Binge-purging-BPAN) and polymorphisms within five genes encoding for proteins involved in the serotoninergic system.

METHODS

In order to carry out this investigation we have conducted a case-control association study on 226 females meeting the criteria for AN, and 678 matched healthy females.

RESULTS

Our data show a significant association between polymorphisms with the gene encoding HTR2A with both AN subtypes, an association between polymorphisms within the genes encoding HTR1D and HTR1B with RAN, and an association between polymorphisms within the gene encoding HTR2C with BPAN. No associations were found for any polymorphisms of the serotonin transporter gene. This outcome indicates a substantial and complex inter-relationship between serotoninergic genes and AN.

CONCLUSIONS

Given these data we hypothesis that the expression or control of expression of several genes of the serotoninergic system, and interactions between these genes, could exert considerable influence over the specific symptomatology of the subtypes of AN.

5-HT1A receptor activation is necessary for 5-MeODMT-dependent potentiation of feeding inhibition

We propose a translational approach to the study of anorexia nervosa (AN) based on our human subject studies where there are characteristic elevations in 5-HT(1A) receptor binding, associated harm avoidance behaviors, reduced impulsivity, and comorbid anxiety disorders. Towards this goal, the hyponeophagia assay was implemented whereby food-deprived mice show increased latency to begin feeding in a novel, anxiogenic environment. The non-selective serotonin agonist, 5-MeODMT, potentiates feeding inhibition compared to the inhibition generated by the anxiogenic environment in a drug-by-environment interaction. Thus, using hyponeophagia in mice, it was possible to study the following key components of AN: anxiety; feeding inhibition; and a modulatory role of the serotonergic system. A major prediction of the proposed AN model is that 5-HT(1A) receptor activation is necessary for feeding inhibition. In support of this model, the 5-HT(1A) receptor antagonist, WAY100635, reverses the 5-MeODMT-dependent potentiation of feeding inhibition. Our findings hint at a mechanistic role for increased 5-HT(1A) receptor activation in restricting-type AN. Further implications for the interplay between anxiety and feeding inhibition in AN are discussed.

New insights into symptoms and neurocircuit function of anorexia nervosa

Individuals with anorexia nervosa have a relentless preoccupation with dieting and weight loss that results in severe emaciation and sometimes death. It is controversial whether such symptoms are secondary to psychosocial influences, are a consequence of obsessions and anxiety or reflect a primary disturbance of brain appetitive circuits. New brain imaging technology provides insights into ventral and dorsal neural circuit dysfunction - perhaps related to altered serotonin and dopamine metabolism - that contributes to the puzzling symptoms found in people with eating disorders. For example, altered insula activity could explain interoceptive dysfunction, and altered striatal activity might shed light on altered reward modulation in people with anorexia nervosa.

Neurobiology of anorexia and bulimia nervosa

Anorexia nervosa (AN) and bulimia nervosa (BN) are related disorders of unknown etiology that most commonly begin during adolescence in women. AN and BN have unique and puzzling symptoms, such as restricted eating or binge-purge behaviors, body image distortions, denial of emaciation, and resistance to treatment. These are often chronic and relapsing disorders, and AN has the highest death rate of any psychiatric disorder. The lack of understanding of the pathogenesis of this illness has hindered the development of effective interventions, particularly for AN. Individuals with AN and BN are consistently characterized by perfectionism, obsessive-compulsiveness, and dysphoric mood. Individuals with AN tend to have high constraint, constriction of affect and emotional expressiveness, ahendonia and asceticism, whereas individuals with BN tend to be more impulsive and sensation seeking. Such symptoms often begin in childhood, before the onset of an eating disorder, and persist after recovery, suggesting they are traits that create a vulnerability for developing an ED. There is growing acknowledgement that neurobiological vulnerabilities make a substantial contribution to the pathogenesis of AN and BN. Considerable evidence suggests that altered brain serotonin (5-HT) function contributes to dysregulation of appetite, mood, and impulse control in AN and BN. Brain imaging studies, using 5-HT specific ligands, show that disturbances of 5-HT function occur when people are ill, and persist after recovery from AN and BN. It is possible that a trait-related disturbance of 5-HT neuronal modulation predates the onset of AN and contributes to premorbid symptoms of anxiety, obsessionality, and inhibition. This dysphoric temperament may involve an inherent dysregulation of emotional and reward pathways which also mediate the hedonic aspects of feeding, thus making these individuals vulnerable to disturbed appetitive behaviors. Restricting food intake may become powerfully reinforcing because it provides a temporary respite from dysphoric mood. Several factors may act on these vulnerabilities to cause AN to start in adolescence. First, puberty-related female gonadal steroids or age-related changes may exacerbate 5-HT dysregulation. Second, stress and/or cultural and societal pressures may contribute by increasing anxious and obsessional temperament. Individuals with AN may discover that reduced dietary intake, by reducing plasma tryptophan availability, is a means by which they can modulate brain 5-HT functional activity and anxious mood. People with AN enter a vicious cycle which accounts for the chronicity of this disorder because caloric restriction results in a brief respite from dysphoric mood. However, malnutrition and weight loss, in turn, produce alterations in many neuropeptides and monoamine function, perhaps in the service of conserving energy, but which also exaggerates dysphoric mood. In summary, this article reviews findings in brain chemistry and neuroimaging that shed new light on understanding the psychopathology of these difficult and frustrating disorders.

Serotonin transporter binding after recovery from eating disorders

RATIONALE

Several lines of evidence suggest that altered serotonin (5-HT) function persists after recovery from anorexia nervosa (AN) and bulimia nervosa (BN).

OBJECTIVES

We compared 11 subjects who recovered (>1 year normal weight, regular menstrual cycles, no binging or purging) from restricting-type AN (REC RAN), 7 who recovered from bulimia-type AN (REC BAN), 9 who recovered from BN (REC BN), and 10 healthy control women (CW).

MATERIALS AND METHODS

Positron emission tomography (PET) imaging with [11C]McN5652 was used to assess the 5-HT transporter (5-HTT). For [11C]McN5652, distribution volume (DV) values were determined using a two-compartment, three-parameter tracer kinetic model, and specific binding was assessed using the binding potential (BP, BP=DVregion of interest/DVcerebellum-1).

RESULTS

After correction for multiple comparisons, the four groups showed significant (p<0.05) differences for [11C]McN5652 BP values for the dorsal raphe and antero-ventral striatum (AVS). Post-hoc analysis revealed that REC RAN had significantly increased [11C]McN5652 BP compared to REC BAN in these regions.

CONCLUSIONS

Divergent 5-HTT activity in subtypes of eating disorder subjects may provide important insights as to why these groups have differences in affective regulation and impulse control.

The 5-HT3 receptor as a therapeutic target

The 5-HT3 receptor is a neurotransmitter-gated ion channel. It is a member of the Cys-loop family of receptors, which also includes nicotinic acetylcholine, glycine and GABAA receptors. Each member of the family consists of an arrangement of five subunits surrounding a central ion-conducting pore. The 5-HT3 receptor binding site is composed of six loops from two adjacent subunits, and the critical ligand binding residues within these loops are well documented. There are a range of 5-HT3 receptor agonists and competitive antagonists, but it is the antagonists that dominate their clinical use. Studies have proposed a range of disease symptoms that might be amenable to 5-HT3 receptor selective compounds; however, so far only the treatment of emesis and irritable bowel syndrome have been fully realised. In this review, the authors look at the structure, function and distribution of 5-HT3 receptors and how this may influence their role in disease. The authors also describe the existing clinical applications of 5-HT3 antagonists and the future potential of these drugs.

Neuroendocrine effects of citalopram infusion in anorexia nervosa

Because of the role of serotonin (5HT) in regulating food intake and mood, several studies have focused their attention on the assessment of serotonergic activity in eating disorders, and in particular in anorexia nervosa, but the results have been inconsistent. Citalopram, a highly selective 5HT reuptake inhibitor, has been recently reported as a neuroendocrine probe to assess the serotonergic function in physiological and pathological conditions. We evaluated the adrenocorticotropic hormone (ACTH), cortisol, prolactin (PRL) and growth hormone (GH) secretion during placebo or citalopram IV infusion (20 mg over 120 min), in six women with anorexia nervosa restricter type, and in six healthy women, in order to test the hypothesis that this neurotransmitter system is abnormal in this group of patients. ACTH and PRL secretion was higher during citalopram infusion compared to placebo (p<0.05) in both groups, while cortisol secretion was higher during citalopram infusion only in healthy controls (p<0.05), but not in anorexic patients. GH levels were unaffected by citalopram in both groups. These results demonstrate that serotonergic activation by citalopram affects corticotroph and lactotroph but not somatotroph secretion in anorexic as well as in normal subjects. Our preliminary findings do not support the existence of remarkable alterations in the serotonergic control of anterior pituitary function in anorexia nervosa, while there seems to be an impairment of the adrenal function in this group of patients.

Olanzapine use in adolescent anorexia nervosa

Several case reports and open label trials describe olanzapine in the treatment of anorexia nervosa (AN). We report 5 adolescents with AN who received olanzapine in addition to psychotherapy for their eating disorder. Body mass index (BMI) of each case increased while on olanzapine. At doses of 5 mg per day and above, patients reported decreased anxiety around eating, improved sleep, and decreased rumination about food and body concerns. Morning sedation was the most commonly reported adverse effect. Olanzapine appeared to be useful in addition to psychotherapy for these adolescents. This report augments a limited literature on the treatment of this disorder, and an almost nonexistent literature specific to pharmacotherapy for adolescents with AN.

Antidepressants for anorexia nervosa

BACKGROUND

Anorexia Nervosa (AN) is an illness characterised by extreme concern about body weight and shape, severe self-imposed weight loss, and endocrine dysfunction. In spite of its high mortality, morbidity and chronicity, there are few intervention studies on the subject.

OBJECTIVES

The aim of this review was to evaluate the efficacy and acceptability of antidepressant drugs in the treatment of acute AN.

SEARCH STRATEGY

The strategy comprised of database searches of the Cochrane Collaboration Depression, Anxiety and Neurosis Controlled Trials Register, MEDLINE (1966 to April 28th, 2005), EMBASE (1980 to week 36, 2004), PsycINFO (1969 to August week 5, 2004), handsearching the International Journal of Eating Disorders and searching the reference lists of all papers selected. Personal letters were sent to researchers in the field requesting information on unpublished or in-progress trials.

SELECTION CRITERIA

All randomised controlled trials of antidepressant treatment for AN patients, as defined by the Diagnostic and Statistical Manual, fourth edition (DSM-IV) or similar international criteria, were selected.

DATA COLLECTION AND ANALYSIS

Quality ratings were made giving consideration to the strong relationship between allocation concealment and potential for bias in the results; studies meeting criteria A and B were included. Trials were excluded if non-completion rates were above 50%. The standardised mean difference and relative risk were used for continuous data and dichotomous data comparisons, respectively. Whenever possible, analyses were performed according to intention-to-treat principles. Heterogeneity was tested with the I-squared statistic. Weight change was the primary outcome. Secondary outcomes were severity of eating disorder, depression and anxiety symptoms, and global clinical state. Acceptability of treatment was evaluated by considering non-completion rates.

MAIN RESULTS

Only seven studies were included. Major methodological limitations such as small trial size and large confidence intervals decreased the power of the studies to detect differences between treatments, and meta-analysis of data was not possible for the majority of outcomes. Four placebo-controlled trials did not find evidence that antidepressants improved weight gain, eating disorder or associated psychopathology. Isolated findings, favouring amineptine and nortriptyline, emerged from the antidepressant versus antidepressant comparisons, but cannot be conceived as evidence of efficacy of a specific drug or class of antidepressant in light of the findings from the placebo comparisons. Non-completion rates were similar between the compared groups.

AUTHORS' CONCLUSIONS

A lack of quality information precludes us from drawing definite conclusions or recommendations on the use of antidepressants in acute AN. Future studies testing safer and more tolerable antidepressants in larger, well designed trials are needed to provide guidance for clinical practice.

MicroPET imaging in an animal model of anorexia nervosa

Anorexia nervosa is a life-threatening psychiatric disorder characterized by severe weight loss and high rates of comorbidity and mortality. The current study assessed the feasibility of using microPET imaging to study the effects of chronic food restriction in an animal model of anorexia nervosa. To establish preliminary support for this model, we hypothesized that chronic food restriction would decrease relative 2-deoxy-2-[18F]fluoro-D-glucose (18FDG) uptake in the rat, in effect modeling cerebral glucose hypometabolism reported in the clinical population of anorexia nervosa. Nine adolescent Wistar female rats received a baseline 18FDG scan. The control group received free access to food for a period of 25 days. The food restricted (FR) group received 40% of their baseline daily food intake until a 30% weight loss occurred; body weight was then maintained at 70% of baseline by adjusting daily food intake. The FR group also had free access to a running wheel for a mean period of 10.8+/-6.1 days. Both groups received a follow-up 18FDG scan. Relative 18FDG uptake was significantly increased in the cerebellum and significantly decreased in the hippocampus and striatum in the FR group compared to controls. Moreover, there was a trend towards a decrease in relative 18FDG uptake in the thalamus in the FR compared to control group. This is the first study to establish support for the use of microPET imaging in an animal model of anorexia nervosa as a means for studying the neurobiological changes that occur due to chronic food restriction.

New targets in the treatment of anorexia nervosa

The pathophysiology of anorexia nervosa (AN) is complex and involves alterations of serotonin, dopamine and histamine neurotransmitters. In addition, receptor activity is disturbed, presumably in response to the neurotransmitter changes. These alterations are reviewed in relation to symptomatology and outcome of AN. Neuropeptide and peripheral orexigenic and satiety peptide research is in its infancy but holds much promise to shed light on the pathophysiological mechanisms involved in this illness. Current drug therapies have not demonstrated the efficacy desired in the treatment of AN. Current therapies are reviewed and new drug targets are explored. Compounds that interact with serotonin, histamine and dopamine receptors may offer unique treatment opportunities. In the future, the manipulation of peptides may add to the therapeutic potential of pharmacotherapy.

Serotonergic and dopaminergic systems in anorexia nervosa: a role for atypical antipsychotics?

OBJECTIVE

To review serotonergic and dopaminergic system function in anorexia nervosa in terms of potential modulation by atypical antipsychotic medications.

METHOD

A systematic review of clinical, neurobiological and functional neuroimaging findings of serotonergic and dopaminergic system activity in anorexia nervosa was conducted via MEDLINE, PsycINFO and EMBASE psychiatry databases, with a critical review of dysregulation of these systems as therapeutic targets for atypical antipsychotics, in context of evidence regarding the utility and efficacy of these medications in this syndrome.

RESULTS

There is evidence of persistently altered serotonergic and dopaminergic function in anorexia nervosa independent to weight-recovery. Case reports, open-label and single-blinded studies, albeit sparse, suggest that atypical antipsychotics may be beneficial in the management of anorexia nervosa psychopathology beyond weight gain.

CONCLUSIONS

Double-blind placebo controlled studies of atypical antipsychotics in anorexia nervosa with well defined outcome measures are required.

Selective serotonin re-uptake inhibitors in anorexia nervosa

Anorexia nervosa (AN), one of the major eating disorders, is a primarily psychiatric illness affecting a number of adolescents and young adults. AN usually runs a chronic course and is associated with significant morbidity and mortality. Drug therapy has modest success in its treatment. Various pharmacotherapeutic agents are being tested, with variable success. Selective serotonin re-uptake inhibitors are the one class of drug that has been found to be effective in AN, especially in preventing relapse. This article provides an overview of the current literature on the role of selective serotonin re-uptake inhibitors in the treatment of AN.

Coming to Terms With Risk Factors for Eating Disorders: Application of Risk Terminology and Suggestions for a General Taxonomy

The aims of the present review are to apply a recent risk factor approach (H. C. Kraemer et al., 1997) to putative risk factors for eating disorders, to order these along a timeline, and to deduce general taxonomic questions. Putative risk factors were classified according to risk factor type, outcome (anorexia nervosa, bulimia nervosa, binge-eating disorder, full vs. partial syndromes), and additional factor characteristics (specificity, potency, need for replication). Few of the putative risk factors were reported to precede the onset of the disorder. Many factors were general risk factors; only few differentiated between the 3 eating disorder syndromes. Common risk factors from longitudinal and cross-sectional studies were gender, ethnicity, early childhood eating and gastrointestinal problems, elevated weight and shape concerns, negative self-evaluation, sexual abuse and other adverse experiences, and general psychiatric morbidity. Suggestions are made for the conceptualization of future risk factor studies.

Anxiolytic effects of acute tryptophan depletion in anorexia nervosa

OBJECTIVE

Recent studies have raised the question as to whether a dysregulation of the neurotransmitter serotonin may contribute to the alterations in mood seen in anorexia nervosa (AN). People with AN tend to be anxious, obsessional, perfectionistic, and harm avoidant. These traits are premorbid and persist after recovery. It has been suggested that increased activity of brain serotonin systems could contribute to this pathologic condition. Dieting in AN, which serves to reduce plasma levels of tryptophan (TRP), may serve to reduce symptoms of dysphoric mood.

METHOD

Fourteen women currently symptomatic with AN (ILL AN), 14 women recovered from AN (REC AN), and 15 healthy control women (CW) underwent acute tryptophan depletion (ATD). Measures of psychological state were self-assessed at baseline and hourly after ATD to determine whether ATD would reduce negative mood.

RESULTS

ILL AN and REC AN had significantly higher mean baseline TRP/LNAA (tryptophan/large neutral amino acids) ratios compared with CW. In contrast to placebo, the ATD challenge demonstrated a significantly greater reduction in the TRP/LNAA ratio for ILL AN (-95%) and REC AN (-84%) compared with CW (-70 %). Both the ILL AN and REC AN had a significant reduction in anxiety on the ATD day compared with the placebo day.

DISCUSSION

These data demonstrate that a dietary-induced reduction of TRP, the precursor of serotonin, is associated with decreased anxiety in people with AN. Restricting dietary intake may represent a mechanism through which individuals with AN modulate a dysphoric mood.

Using an exercise-based instrument to detect signs of an eating disorder

The study employed an innovative exercise-based instrument to identify individuals at risk for eating disorder (ED). The Exercise Orientation Questionnaire (EOQ), a reliable and valid instrument, was used to compare 80 ED patients, 74 obese patients, 99 elite runners, and 214 controls from a previous study. Runners resembled ED patients in scoring high on total EOQ and exercise intensity but differed in that the athletes scored low on self-loathing (SLSS), a sub-scale of the EOQ. SLSS scores clearly distinguished clinical (ED, obese) from non-clinical groups, while other sub-scales (self-control, weight loss, and identity) did not. The study suggests that it is feasible to detect ED risk through assessment of exercise attitudes and behaviors. The SLSS subscale of the EOQ can differentiate clinical from non-clinical groups and anorexic patients from healthy individuals with body mass index within the anorexic range. The SLSS could provide a theoretical bridge between compulsive athleticism and ED.