Objective: Network theory considers mental disorders as the product of symptom interaction. A growing number of studies employing this methodology has been conducted in eating disorders (EDs). We aimed to review those studies to provide evidence and limitations for a novel conceptualisation of EDs.Methods: According to PRISMA guidelines and PICOS criteria, studies eligible for inclusion were those employing network analysis in people with a clinically defined diagnosis of ED. Twenty‐five studies were included and were analysed in relation to diagnosis, comorbidity, and treatment outcome.Results: Despite the central role of overvaluation of body shape and weight and cognitive restraint across ED diagnoses, ineffectiveness, interoceptive awareness and affective problems appear central symptoms. Ineffectiveness and interoceptive awareness emerge as bridge symptoms promoting comorbidity in people with anorexia nervosa and in mixed ED samples. Although few studies assessed treatment outcome, there is evidence supporting the predictive role of central network nodes.Conclusions: Ineffectiveness, interoceptive ability and affective problems may be included in the core ED psychopathology, in addition to ED‐specific symptoms. Network analysis is a promising method to reconceptualize comorbidity. Future studies are recommended to include general psychopathology in ED networks, to assess connections with the external field and clinical meaning of network connectivity.

Alterations in the gut microbiome and fecal metabolites have been detected in anorexia nervosa (AN), but differences in those profiles between restricting AN (ANR) and binge-purging AN (ANBP) type have not been explored. We made a secondary analysis of our previous data concerning microbiome and metabolomics profiles of 17 ANR women, six ANBP women and 20 healthy controls (HC). Twelve fecal metabolites differentiating ANR patients, ANBP patients and HC were identified. Both patient groups showed decreased intra-individual bacterial richness with respect to healthy controls (HC). Compared to ANR subjects, ANBP patients had a significant increase in relative abundances of Bifidobacterium, Bifidobacteriaceae, Bifidobacteriales, and Eubacteriacae and a significant decrease in relative abundances of Odoribacter, Haemophilus, Pasteurellaceae, and Pasteurellales. The heatmaps of the relationships of selected fecal metabolites with microbial families showed different structures among the three groups, with the heatmap of ANBP patients being drastically different from that of HC, while that of ANR patients resulted more similar to HC. These findings, although preliminary because of the relatively small sample size, confirm the occurrence of different gut dysbiosis in ANR and ANBP and demonstrate different connections between gut microorganisms and fecal metabolites in the two AN types.

Exposure to trauma during childhood is a non-specific risk factor for psychiatric disorders, including eating disorders (EDs), over the life course. Moreover, an association between stressful life events and the onset/maintenance of EDs has been documented. Therefore, the hypothalamus-pituitary-adrenal (HPA) axis, namely the main component of the endogenous stress response system, has been proposed to be implicated in the pathophysiology of EDs. In this narrative review the current knowledge concerning the effects of early trauma exposure on the HPA axis activity and their putative role in the pathophysiology of EDs will be illustrated. Research findings corroborate the idea that childhood trauma exposure has long-lasting dysregulating effects on the activity of the HPA axis, which may contribute to the biological background of the early trauma-related risk for the development of EDs across the life span. Moreover, literature data support the existence of a "maltreated ecophenotype" in EDs characterized by specific clinic and neuroendocrine features, which may have important implications in treatment programming for such a type of patients.