Eating disorders in childhood and adolescence in the light of clinical and neurobiological findings, typical traits in anorexia nervosa and a brain morphometry study

Research in childhood and adolescence clinical population allows the analysis of the phenomenon in the very beginning of the disturbance in a population in which the effects of the disordered eating have not interfered in a stable manner the neuroendocrine circuits underlying the disease. The nature of eating disorders (EDs) is a controversial issue. A first approach considers EDs as the outcome of dysfunctions in the neuronal processes related to appetite and emotionality (Kaye et al., 2009, 2013). A second approach explains EDs as the outcome of the interaction between cognitive, socio-emotional, and interpersonal elements (Schmidt and Treasure, 2006; Cooper and Fairburn, 2011; Treasure and Schmidt, 2013). The transdiagnostic cognitive-behavioural model proposes that a dysfunctional system of self-evaluation is central to the maintenance of eating disorders (Fairburn, Cooper & Shafran, 2008). Moreover some authors proposed recently an ‘impulse control' spectrum model of eating behaviour. Notablely, despite its apparent appeal, body weight may not be the most accurate measure to indicate one's position on the spectrum (Brooks, Rask-Andersen, Benedict, Schiöth, 2012). Neuroimaging techniques have been useful tools for accurate investigation of brain structure and function in EDs. Specific findings have been a reduction in total gray and white matter volumes in anorexia nervosa (AN) patients compared with healthy controls or the persistence of the gray matter volume changes when weight is restored. A number of regions in the brain help regulate food and weight and previous studies have reported regional brain abnormalities in patients with EDs (Brooks et al., 2011; Joos et al., 2010; McCormick et al., 2008; Suchan et al., 2010). However, the results from these studies are inconsistent, and there is no agreement upon which regions of the brain are most affected. New studies point to the ways only higher human brain regions like the frontal cortex and insula are implicated in the ongoing starvation of AN. These higher brain regions play a crucial role in emotions, personality, and rewards, all of which are thought to be important in anorexia nervosa. It’s important to remember also that the temperament and personality traits that might create a vulnerability for developing AN should be taken into account (e.g. attention to detail, concern about consequences, and a drive to accomplish and succeed) (Kaye & Bailer, 2011; Lask, 2000). This thesis contains doctoral studies about Eating Disorders (EDs) in childhood and adolescence carried out in the past 3 years and has been organized in an introduction and in five different studies. The aim of the first study was to investigate the prevalence risk for developing AN in a very wide sample of adolescents 15-19 years (17 866 adolescents; 47.8% males; data extracted from ESPAD-Italia®2005 database), obtaining a psychological profile of these at risk subjects, as assessed by the Italian Offer Self-Image Questionnaire (OSIQ). The study also evaluated gender, age, weight, height and eating attitude. The second, third and fourth Chapters described a multicenter national study carried out in 2012-2013 in Italy aimed to investigate a sample of patients 7-18 years old with an eating disorder to determine if the relationships between Eating Disorders (EDs) diagnosis in childhood and adolescence key factors and core eating disorder mechanisms are transdiagnostic. A comparison to distinguish overlapping and specific factors between the various EDs in children and adolescents was performed using principal component analysis. A mixture of transdiagnostic and disorder-specific processes was implicated in the phenomenology of eating disorders in childhood and adolescence; to evaluate more deeply the model, in Chapters three and four – the subtypes of the classical diagnosis of Eating Disorders were taken in account. These sections are aimed to underline the utility of sub typing analysis in the cognitive-behavioral maintaining factors model of Eating Disorders in childhood and adolescence with a focus on Anorexia Nervosa restricting subtype. The fifth and last chapter describes a study that stems from the collaboration with the the National Institute of Nuclear Physics (INFN) and concerns a MRI investigation of brain structure in anorexia nervosa. As findings support the utility of the examination on personality subtypes in EDs research, the section described the preliminary steps towards a study of structural magnetic resonance focusing on restricting-type Anorexia Nervosa adolescent patients. The purpose of this section was to undertake an investigation on whole brain volumes of a sample of 24 AN restrictive type (AN-R) adolescent patients using voxel - based morphometry and compare them with a same age and gender sample of 24 healthy control subjects. Moreover we aimed to relate the exploratory results of whole brain volumes and region of interest (ROI) analysis with measures of key features of AN-R adolescent patients.