Backstage of Eating Disorder—About the Biological Mechanisms behind the Symptoms of Anorexia Nervosa

Abstract

Anorexia nervosa (AN) represents a disorder with the highest mortality rate among all psychiatric diseases, yet our understanding of its pathophysiological components continues to be fragmentary. This article reviews the current concepts regarding AN pathomechanisms that focus on the main biological aspects involving central and peripheral neurohormonal pathways, endocrine function, as well as the microbiome–gut–brain axis. It emerged from the unique complexity of constantly accumulating new discoveries, which hamper the ability to look at the disease in a more comprehensive way. The emphasis is placed on the mechanisms underlying the main symptoms and potential new directions that require further investigation in clinical settings.

Is the Activity-Based Anorexia Model a Reliable Method of Presenting Peripheral Clinical Features of Anorexia Nervosa?

“…Nonetheless, the increasing prevalence of AN does not run parallel with the available treatment options. The importance of psychological and socio-cultural factors in the development of AN is widely established; however, metabolic dysregulation is evident as well [ 11 ]. Thus, it would be unrealistic to build an animal model upon the entire AN pathology.…”

“…And those patients do not adequately respond to homeostatic body signals such as appetite regulating peptides that should trigger weight restoration [ 46 ]. The central aspects related to AN etiopathogenesis (for a review see, Skowron et al 2020) [ 11 ] are beyond the scope of this article; however, it should be noted that research using animal models, including the ABA model, has contributed immensely to the understanding of potential brain mechanisms that many underlie the causes and consequences of aberrant eating behaviors [ 48 , 49 , 50 ].…”

Possible role of the gut microbiota in the pathogenesis of anorexia nervosa

“…Based on 16S rRNA sequencing methods, we also reported a lower relative abundance of the phylum Bacteroidetes in patients with AN than healthy age-matched controls [ 51 ]. As summarized in Table 3 , several recently published papers [ 52 – 57 ] have also shown changes in gut microbial ecology at the phylum or genus levels; however, no specific bacteria were identified among these reports. Thus, although the results differ depending on the patient’s background or analytical methods, “gut dysbiosis” is consistently observed in patients with AN.…”

Fractalkine, sICAM-1 and Kynurenine Pathway in Restrictive Anorexia Nervosa–Exploratory Study

“…However, within the last decades, an increased occurrence of AN in the high risk-group of 15–19-year-old girls has been observed [ 2 , 3 ]. The disease still presents a great therapeutic challenge, due to the lack of efficacious treatment [ 4 ]. The complex etiology of AN involves genetic, developmental, psychological and socio-cultural factors.…”

“…The complex etiology of AN involves genetic, developmental, psychological and socio-cultural factors. Alterations of the hypothalamic–pituitary–adrenal (HPA) axis, changes in the neurotransmitter systems and immune dysfunction have all been linked to the disturbed regulation of food intake in AN [ 4 , 5 , 6 ]. The contribution of altered immune response to the pathogenesis of AN is an attractive hypothesis; however, the available data are rare and the results are often contradictory [ 7 , 8 ].…”