Atypical anorexia nervosa (atypical AN) appears to be a heterogeneous disorder under the current diagnostic system. Though the body mass index (BMI) cutoff point of 18.5 kg/m2 is a criterion that distinguishes atypical AN from AN, the cutoff may not be universally applicable as the norms for BMI vary and can be affected by several factors, including cross-country differences and social determinants. It is unfortunate that we do not yet have reliable or widely available criteria other than BMI for the diagnosis of atypical AN. Additional relevant markers of atypical AN are needed in future diagnostic systems.

In this paper, I integrate a theory of body image, weight control, and addiction in a life cycle model with health deficit accumulation in order to explain the phenomenon of anorexia nervosa and its impact on health and longevity. Individuals consume normal goods and foods and can work off excess calories with physical exercise. There exists a healthy body mass index and deviations from it increasingly cause health deficits due to obesity or underweight. There exists also a subjective target weight and being heavier than target weight causes a loss of utility from body image. Anorexia is initiated in individuals who are particularly successful in weight control and prone to addiction. Addiction to weight control motivates anorexic individuals to perpetually adjust their target weight downwards and to eat less and exercise more. With declining weight, health deficits accumulate faster and mortality risk rises. I calibrate the model to an average American woman with bmi 28. Due to weight loss addiction, the bmi declines to a level of 15 and causes an expected loss of 15 years of life. I also discuss potential therapies and recovery from the disease.

The recent systematic review by Walsh, Hagan, & Lockwood (Int J Eat Disord, in press) highlights the importance of further distinguishing atypical anorexia nervosa (atypical AN) from other feeding and eating disorders. The lack of a trumping scheme within other specified feeding or eating disorder (OSFED) hinders intervention selection in the clinical context and reduces reliability of diagnostic classification in research samples. Thus, we propose a trumping scheme within OSFED that mirrors the existing diagnostic algorithm in the main DSM-5-TR feeding and eating disorders section. According to this scheme, a diagnosis of atypical AN would override all other OSFED subcategories. Subthreshold bulimia nervosa (BN) would trump subthreshold binge-eating disorder (BED) and purging disorder; purging disorder would trump subthreshold BED and night eating syndrome; night eating syndrome would trump subthreshold BED; and subthreshold BED would trump subthreshold avoidant/restrictive food intake disorder (ARFID)-a novel presentation that we propose adding under the OSFED umbrella to parallel the existing subthreshold classifications for the main feeding and eating disorders. We hope this proposed OSFED trumping scheme will improve intervention selection and diagnostic reliability in clinical and research contexts, and serve as a catalyst for future research on these newly recognized-but common and impairing-feeding and eating disorder presentations.

The applicability of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria for anorexia nervosa (AN) and atypical AN to individuals having undergone bariatric surgery poses several challenges due to the atypical presentation of AN-like symptoms in this population. We describe these challenges, propose modifications to the corresponding diagnostic criteria, and delineate areas of research to inform possible adaptations of atypical AN criteria with applicability to postbariatric surgery populations. We discuss the utility of a strict definition of "significantly low weight" and "significant weight loss" as part of DSM-5 Criterion A for AN and atypical AN, highlighting the importance of clinical judgment. We also question the clinical distinction between AN and atypical AN based solely on weight and argue that the hallmark feature of both diagnoses in postbariatric surgery populations should be persistent energy intake restriction coupled with persistent weight-control behaviors. Finally, criteria B and C need to allow the distinction between common concerns of bariatric surgery patients regarding weight and eating, and clinically relevant symptoms of atypical AN and AN. Knowing the rates, the specificities, and the impact of atypical AN on postsurgical weight loss has important implications for the clinical attention of these often-overlooked patients.

We examined the neural underpinnings of the effects of mindfulness on anxiety in anorexia nervosa using functional magnetic resonance imaging in 21 anorexia patients. We used a functional magnetic resonance imaging task designed to induce weight-related anxiety and asked participants to regulate their anxiety either using or not using an acceptance strategy. Our results showed reduced activity in the amygdala, anterior cingulate cortex, putamen, caudate, orbital gyrus, middle frontal gyrus, posterior cingulate cortex and precuneus following a mindfulness-based intervention. The present study provides new insight regarding the neural mechanisms underlying the effect of mindfulness-based intervention in ameliorating anorexia nervosa.

Changes made to the DSM Eating Disorders over the years have aimed to reduce the prevalence of the residual DSM Eating Disorder categories (e.g., Other Specified Eating Disorder). Atypical Anorexia Nervosa (AN), included since DSM-IV as an example of a presentation not meeting criteria for a specific eating disorder, appears to be more prevalent than AN. It is defined as meeting all of the criteria for AN except that, after significant weight loss, weight is at or above normal. As suggested by the Walsh et al. review, lack of definitional precision will likely complicate efforts to determine whether atypical AN is best considered a variant of AN or a distinct category. Problems with the current definition of atypical AN include (1) a lack of precision regarding what constitutes "significant" weight loss; (2) whether the weight loss can occur at any point in the individual's lifetime; and (3) whether there an upper limit to weight being above normal. It is suggested that researchers develop consensus diagnostic criteria and assessment tools to facilitate the collection of empirical data about atypical AN in order to lay the groundwork for future decisions about its nosological status.

The medical complications of eating disorders (EDs) have been described in the literature; however, the pulmonary system has historically been described as relatively spared from the ravages of eating disorders and thus neglected in the literature. Here we review the pulmonary complications that have been described in the literature, including the effects of starvation on the lungs of nutritionally deprived animals and patients with anorexia nervosa. There is clear evidence of weakness of respiratory muscles with starvation in both groups. However, there is discordance in the literature as to whether starvation results in "nutritional emphysema," and if so, by what mechanism and at what degree of malnutrition it develops. We also explore the growing concern for the risk of non-tuberculosis mycobacterium infection as well as risk for pneumomediastinum and pneumothorax in patients with restrictive EDs. From the limited literature, it is clear the lungs, in fact, are not spared and that further research is needed to fully understand the full extent of pulmonary complications instigated by EDs.

Assessing the validity of a psychometric test is fundamental to ensure a reliable interpretation of its outcomes. Few attempts have been made recently to complement classical approaches (e.g., factor models) with a novel technique based on network analysis. The objective of the current study is to carry out a network-based validation of the Eating Disorder Inventory 3 (EDI-3), a questionnaire designed for the assessment of eating disorders. Exploiting a reliable, open source sample of 1206 patients diagnosed with an eating disorder, we set up a robust validation process encompassing detection and handling of redundant EDI-3 items, estimation of the cross-sample psychometric network, resampling bootstrap procedure and computation of the median network of the replica samples. We then employed a community detection algorithm to identify the topological clusters, evaluated their coherence with the EDI-3 subscales and replicated the full validation analysis on the subpopulations corresponding to patients diagnosed with either anorexia nervosa or bulimia nervosa. Results of the network-based analysis, and particularly the topological community structures, provided support for almost all the composite scores of the EDI-3 and for 2 single subscales: Bulimia and Maturity Fear. A moderate instability of some dimensions led to the identification of a few multidimensional items that should be better located in the intersection of multiple psychological scales. We also found that, besides symptoms typically attributed to eating disorders, such as drive for thinness, also non-specific symptoms like low self-esteem and interoceptive deficits play a central role in both the cross-sample and the diagnosis-specific networks. Our work adds insights into the complex and multidimensional structure of EDI-3 by providing support to its network-based validity on both mixed and diagnosis-specific samples. Moreover, we replicated previous results that reinforce the transdiagnostic theory of eating disorders.

Impairment in cognitive flexibility is a core symptom of anorexia nervosa (AN) and is associated with treatment resistance. Nevertheless, studies on the neural basis of cognitive flexibility in adolescent AN are rare. This study aimed to investigate brain networks underlying cognitive flexibility in adolescents with AN. To address this aim, participants performed a Dimensional Change Card Sorting task during high-density EEG recording. Anxiety was measured with the State-Trait Anxiety Inventory. Data were collected on 22 girls with AN, and 23 controls. Evoked responses were investigated using global-spatial analysis. Adolescents with AN showed greater overall accuracy, fewer switch trial errors, and reduced inverse efficiency switch cost relative to controls, although these effects disappeared after adjusting for trait and state-anxiety. EEG results indicated augmented early visual orienting processing (P100), and subsequent impaired attentional mechanisms to task switching (P300b) in subjects with anorexia nervosa. During task switching, diminished activations in subjects with AN were identified in the posterior cingulate, calcarine sulcus, and cerebellum, and task repetitions induced diminished activations in a network involving the medial prefrontal cortex, and several posterior regions, compared with controls. No significant associations were found between measures of cognitive flexibility and anxiety in the AN group. Findings of this study suggest atypical neural mechanisms underlying cognitive flexibility in adolescents with AN. More importantly, our findings suggest that different behavioral profiles in AN could relate to differences in anxiety levels. Future research should investigate the efficacy of cognitive training to rebalance brain networks of cognitive flexibility in AN.

Anorexia nervosa is a disorder associated with serious adverse health outcomes, for which there is currently considerable treatment ineffectiveness. Characterised by restrictive eating behaviours, distorted body image perceptions and excessive physical activity, there is growing recognition anorexia nervosa is associated with underlying dysfunction in excitatory and inhibitory neurometabolite metabolism and signalling. This narrative review critically explores the role of N-methyl-D-aspartate receptor-mediated excitatory and inhibitory neurometabolite dysfunction in anorexia nervosa and its associated biomarkers. The existing magnetic resonance spectroscopy literature in anorexia nervosa is reviewed and we outline the brain region-specific neurometabolite changes that have been reported and their connection to anorexia nervosa psychopathology. Considering the proposed role of dysfunctional neurotransmission in anorexia nervosa, the potential utility of zinc supplementation and sub-anaesthetic doses of ketamine in normalising this is discussed with reference to previous research in anorexia nervosa and other neuropsychiatric conditions. The rationale for future research to investigate the combined use of low-dose ketamine and zinc supplementation to potentially extend the therapeutic benefits in anorexia nervosa is subsequently explored and promising biological markers for assessing and potentially predicting treatment response are outlined.

Anorexia nervosa (AN) is a complex psychiatric disorder accompanied by a variety of endocrine effects. Altered levels of the sex steroid hormones progesterone and dehydroepiandrosterone (DHEA) have been shown to occur in patients with AN using short-term hormonal measurement methods based on blood, saliva, and urine samples. However, since sex steroid hormone levels fluctuate during the menstrual cycle, these measurement methods require a great deal of effort due to the need to collect multiple samples in order to correctly determine the basal level of sex hormones. In contrast, hair-based assessments provide a marker of accumulated longer-term hormone exposure using a single, non-invasive sample. The aim of this study was to investigate sex steroid hormone levels via hair-based assessments in acutely underweight AN in comparison with healthy, age-matched, female control participants. Additionally, we compared progesterone and DHEA hair levels longitudinally during inpatient treatment in AN. Collected hair samples were analyzed using liquid chromatography-mass spectrometry (LC-MS/MS) to determine a monthly hormone level of progesterone and DHEA. Our results indicate that DHEA hair hormone levels were similar across groups but progesterone was suppressed in underweight AN compared with healthy controls. In the longitudinal design, no significant change in hair hormone levels during partial weight restoration in patients with AN was observed. Our findings suggest that hair analysis can be used to detect suppressed progesterone levels in severe AN, and that progesterone does not increase during short-term weight restoration.

The study of the effects of the COVID-19 pandemic on individuals who attended mental health services is needed to identify the specific vulnerabilities associated to this challenging period. Despite several analyses reporting the worsening of eating disorders symptomatology after the beginning of the pandemic, characterizations of adult inpatients with eating disorders are still lacking. We conducted a retrospective analysis to assess whether adult individuals who underwent hospitalization in a specialized eating disorders unit in the two years after the beginning of the COVID-19 pandemic differed in clinical presentation, psychopathological measures, and treatment outcomes from inpatients hospitalized in the two years before. In the comparison between the two groups, the individuals who began treatment after the start of the pandemic presented with more physical hyperactivity and more severe psychopathological scores in most of the areas investigated, with differences in eating symptoms still evident at discharge. Notably, body-related symptoms (i.e., body shape concerns, body checking, body avoidance) were associated with the pandemic, and also for inpatients with extreme anorexia nervosa. This retrospective analysis does not allow us to separate the impact of COVID-19 from other potentially relevant co-occurring factors; however, these findings help in understanding how the pandemic could have affected individuals that needed specialized intensive treatment.