Psychoneuroendocrinology of anorexia nervosa

Assessing for Eating Disorders: A Primer for Gastroenterologists

Eating disorders involve irregularities in eating behavior that may cause gastrointestinal (GI) symptoms. Consequently, many patients with eating disorders seek gastroenterological healthcare at some point in their illness, with many seeking this care even before they seek treatment for and/or diagnosed with their eating disorder. As such, the gastroenterology provider is in a unique position to identify, manage, and facilitate treatment for an eating disorder early in the course of the illness. Although assessing eating disorders is already a difficult task, the identification of eating disorders in patients with GI disease represents an even greater challenge. In particular, common GI symptoms, such as nausea, vomiting, and bloating, may disguise an eating disorder because these symptoms are often viewed as a sufficient impetus for dietary restriction and subsequent weight loss. In addition, the focus on identifying an organic etiology for the GI symptoms can distract providers from considering an eating disorder. During this prolonged diagnostic evaluation, the eating disorder can progress in severity and become more difficult to treat. Unfortunately, a misconception that hinders eating disorder detection is the notion that the rate or method of weight loss is associated with an eating disorder. Regardless of whether weight loss is slow or rapid, purposeful or accidental, eating disorder behaviors and thought patterns may be present. Unidentified eating disorders are not only dangerous in their own right but also can interfere with effective management of GI disease and its symptoms. As such, it is imperative for the GI provider to remain well versed in the identification of these diseases.

Verifying Feighner's Hypothesis; Anorexia Nervosa Is Not a Psychiatric Disorder

Mental causation takes explanatory priority over evolutionary biology in most accounts of eating disorders. The evolutionary threat of starvation has produced a brain that assists us in the search for food and mental change emerges as a consequence. The major mental causation hypothesis: anxiety causes eating disorders, has been extensively tested and falsified. The subsidiary hypothesis: anxiety and eating disorders are caused by the same genotype, generates inconsistent results because the phenotypes are not traits, but vary along dimensions. Challenging the mental causation hypothesis in Feighner et al. (1972) noted that anorexic patients are physically hyperactive, hoarding for food, and they are rewarded for maintaining a low body weight. In 1996, Feighner's hypothesis was formalized, relating the patients' behavioral phenotype to the brain mechanisms of reward and attention (Bergh and Södersten, 1996), and in 2002, the hypothesis was clinically verified by training patients how to eat normally, thus improving outcomes (Bergh et al., 2002). Seventeen years later we provide evidence supporting Feighner's hypothesis by demonstrating that in 2012, 20 out of 37 patients who were referred by a psychiatrist, had a psychiatric diagnosis that differed from the diagnosis indicated by the SCID-I. Out of the 174 patients who were admitted in 2012, most through self-referral, there was significant disagreement between the outcomes of the SCID-I interview and the patient's subjective experience of a psychiatric problem in 110 of the cases. In addition, 358 anorexic patients treated to remission scored high on the Comprehensive Psychopathological Rating Scale, but an item response analysis indicated one (unknown) underlying dimension, rather than the three dimensions the scale can dissociate in patients with psychiatric disorders. These results indicate that psychiatric diagnoses, which are reliable and valid in patients with psychiatric disorders, are less well suited for patients with anorexia. The results are in accord with the hypothesis of the present Research Topic, that eating disorders are not always caused by disturbed psychological processes, and support the alternative, clinically relevant hypothesis that the behavioral phenotype of the patients should be addressed directly.

How to Deal With Temporal Relationships Between Biopsychosocial Variables: A Practical Guide to Time Series Analysis

OBJECTIVE

Longitudinal data allow for conclusions about the temporal order of events and interactional dynamics between several processes. The aim of this article is to provide a concise and pragmatic description of time series analyses (TSAs) of patient samples with numerous (or daily) repeated biological, behavioral, or psychological measurements. In addition, the article demonstrates how to implement the described analyses with the software R.

METHODS

To illustrate the concrete application of the time series method, we use two case series of patients with anorexia nervosa. Upon awakening, the patients collected salivary cortisol on a daily basis and answered several questions on a handheld computer (electronic diary) regarding psychosocial variables at the time of salivary collection.

RESULTS

Basic concepts of time series analysis such as stationarity, auto- and cross-correlation, Granger causality, impulse response function, and variance decomposition are presented. In addition, we demonstrate vector autoregressive analyses with three variables. For Patient 1, we demonstrate how TSA is used to detect cortisol and anxiety decreases during inpatient treatment and also how TSA can be used to show that an increase in cortisol is followed by a next-day increase in anxiety. For Patient 2, TSA was used to show higher salivary cortisol upon awakening on the days the patient was weighed compared with other days. In addition, we show how interdependencies of depressive feelings, positive anticipations, and cortisol values can be quantified using TSA.

CONCLUSIONS

Time series designs enable modeling of temporal relationships and bidirectional associations between biopsychosocial variables within individuals. These individual patterns cannot be derived from traditional group-based statistical analyses. This article provides accessible research tools for conducting TSA relevant to psychosomatic and biobehavioral research.

Aspectos da leptina na anorexia nervosa: possíveis efeitos benéficos no tratamento da hiperatividade

Pesquisas recentes demonstram a relação direta da leptina na regulação do balanço energético e como um dos fatores envolvidos em transtornos alimentares. Com ação no sistema nervoso central, a leptina interfere na ingestão alimentar, no metabolismo da glicose, no peso corporal, na produção de hormônios sexuais e na atividade física. As pesquisas realizadas tanto em seres humanos como em animais demonstram que a queda nos níveis de leptina está relacionada aos sintomas apresentados na anorexia nervosa: a baixa ingestão alimentar, a perda excessiva de peso corporal, a amenorréia e a hiperatividade. Assim, o grau de hipoleptinemia não é apenas uma forte indicação de baixa reserva de tecido adiposo, mas também de severa desordem, sendo que os níveis de leptina podem ser utilizados para avaliar melhor a gravidade da doença. Pesquisas estão sendo realizadas com o objetivo de discutir a possibilidade de utilização da leptina como coadjuvante no tratamento de pacientes com anorexia nervosa para a diminuição da hiperatividade. Acredita-se que o tratamento com leptina associado à medicação e à psicoterapia, poderia ser benéfico em pacientes anoréxicas extremamente ativas, deixando-as mais suscetíveis ao tratamento adicional. Uma realimentação suficiente, a medicação, a psicoterapia e um ambiente acolhedor durante o tratamento com leptina devem ser assegurados. Assim, este artigo tem como objetivo discorrer sobre a leptina e aspectos relacionados à anorexia, e discutir como esta informação pode ser importante na avaliação clínica de pacientes com este transtorno alimentar.

Towards a neurocircuitry in anorexia nervosa: evidence from functional neuroimaging studies

Functional neuroimaging is widely used to unravel changes in brain functioning in psychiatric disorders. In the current study, we review single-photon emission tomography (SPECT), positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) studies in anorexia nervosa (AN), a difficult-to-treat eating disorder with the highest mortality rate among psychiatric disorders. We discuss the role of the parietal cortex, anterior and subgenual cingulate cortex, frontal cortex and temporal lobe in light of the cardinal symptoms of AN. The insights of the current review may ultimately lead to the development of new treatments.

High ambient temperature reverses hypothalamic MC4 receptor overexpression in an animal model of anorexia nervosa

The potential involvement of the melanocortin system in the beneficial effects of heat application in rats submitted to activity-based anorexia (ABA), an analogous model of anorexia nervosa (AN), was studied. Once ABA rats had lost 20% of body weight, half of the animals were exposed to a high ambient temperature (HAT) of 32 degrees C, whereas the rest were maintained at 21 degrees C. Control sedentary rats yoked to ABA animals received the same treatment. ABA rats (21 degrees C) showed increased Melanocortin 4 (MC4) receptor and Agouti gene Related Peptide (AgRP) expression, and decreased pro-opiomelanocortin (POMC) mRNA levels (Real Time PCR), with respect to controls. Heat application increased weight gain and food intake, and reduced running rate in ABA rats, when compared with ABA rats at 21 degrees C. However, no changes in body weight and food intake were observed in sedentary rats exposed to heat. Moreover, heat application reduced MC4 receptor, AgRP and POMC expression in ABA rats, but no changes were observed in control rats. These results indicate that hypothalamic MC4 receptor overexpression could occur on the basis of the characteristic hyperactivity, weight loss, and self-starvation of ABA rats, and suggest the involvement of hypothalamic melanocortin neural circuits in behavioural changes shown by AN patients. Changes in AgRP and POMC expression could represent an adaptative response to equilibrate energy balance. Moreover, the fact that HAT reversed hypothalamic MC4 receptor overexpression in ABA rats indicates the involvement of brain melanocortin system in the reported beneficial effects of heat application in AN. A combination of MC4 receptor antagonists and heat application could improve the clinical management of AN.

Behavioral neuroendocrinology and treatment of anorexia nervosa

Outcome in anorexia nervosa remains poor and a new way of looking at this condition is therefore needed. To this aim, we review the effects of food restriction and starvation in humans. It is suggested that body weight remains stable and relatively low when the access to food requires a considerable amount of physical activity. In this condition, the human homeostatic phenotype, body fat content is also low and as a consequence, the synthesis and release of brain neurotransmitters are modified. As an example, the role of neuropeptide Y is analyzed in rat models of this state. It is suggested that the normal behavioral role of neuropeptide Y is to facilitate the search for food and switch attention from sexual stimuli to food. Descriptive neuroendocrine studies on patients with anorexia nervosa have not contributed to the management of the patients and the few studies in which hormones have been administered have, at best, reversed an endocrine consequence secondary to starvation. In a modified framework for understanding the etiology and treatment of anorexia nervosa it is suggested that the condition emerges because neural mechanisms of reward and attention are engaged. The neural neuropeptide Y receptor system may be involved in the maintenance of the behavior of eating disorder patients because the localization of these receptors overlaps with the neural systems engaged in cue-conditioned eating in limbic and cortical areas. The eating behavior of patients with anorexia nervosa, and other eating disorders as well, is viewed as a cause of the psychological changes of the patients. Patients are trained to re-learn normal eating habits using external support and as they do, their symptoms, including the psychological symptoms, dissolve.

Research methodology: endocrinologic measurements in exercise science and sports medicine

OBJECTIVE

To provide background information on methodologic factors that influence and add variance to endocrine outcome measurements. Our intent is to aid and improve the quality of exercise science and sports medicine research endeavors of investigators inexperienced in endocrinology.

BACKGROUND

Numerous methodologic factors influence human endocrine (hormonal) measurements and, consequently, can dramatically compromise the accuracy and validity of exercise and sports medicine research. These factors can be categorized into those that are biologic and those that are procedural-analytic in nature.

RECOMMENDATIONS

Researchers should design their studies to monitor, control, and adjust for the biologic and procedural-analytic factors discussed within this paper. By doing so, they will find less variance in their hormonal outcomes and thereby will increase the validity of their physiologic data. These actions can assist the researcher in the interpretation and understanding of endocrine data and, in turn, make their research more scientifically sound.

Neuropeptide Y facilitates activity-based-anorexia

The hypothesis that treatment with neuropeptide Y (NPY) can increase running activity and decrease food intake and body weight was tested. Female rats with a running wheel lost more weight than sedentary rats and ran progressively more as the availability of food was gradually reduced. When food was available for only 1h/day, the rats lost control over body weight. Correlatively, the level of NPY mRNA was increased in the hypothalamic arcuate nucleus. This phenomenon, activity-based-anorexia, was enhanced by intracerebroventricular infusion of NPY in rats which had food available during 2h/day. By contrast, NPY stimulated food intake but not wheel running in rats which had food available continuously. These findings are inconsistent with the prevailing theory of the role of the hypothalamus in the regulation of body weight according to which food intake is a homeostatic process controlled by "orexigenic" and "anorexigenic" neural networks. However, the finding that treatment with NPY, generally considered an "orexigen", can increase physical activity and decrease food intake and cause a loss of body weight is in line with the clinical observation that patients with anorexia nervosa are physically hyperactive and eat only little food despite having depleted body fat and up-regulated hypothalamic "orexigenic" peptides.