Vulnerability factors and developmental trajectories of Eating disorders-relevant attitudes and behaviours in non-clinical adolescents

Eating disorders (EDs) are regarded as a function of pubertal growth, personality, and body image (BI) development, as well as socio-cultural influences, during adolescence. Sex-specificities are getting more attention. However, empirical studies from this broad area of research do not systematically investigate EDs taking into account female and male specificities. The present PhD research project aims to explore vulnerability factors for increases in ED-related behaviours among boys and girls during adolescence, by conducting a 2-year longitudinal study. In literature, the onset and course of ED has been mostly connected with (1) body-related concerns and (dis)satisfaction, and (2) personality variables. However, vulnerability models have mainly been tested on females. Additionally, empirical findings reported mostly on inter-individual differences rather than intra-individual dynamics, with no study systematically investigating them. Body image (BI), and Body Dissatisfaction (BD), moreover, have been often used as interchangeable constructs and operationalized in many different ways, thus contributing to not fully coherent empirical findings. In the current project, we aimed to explore EDs development from an integrative perspective on the role of body-related constructs and personality among adolescent boys and girls, by using 1) a sex-sensitive approach in assessing EDs and 2) between-people and within-person approach simultaneously. In detail, the objectives of the present PhD project were as follows: 1) Defining trends of ED-related behaviours and attitudes, namely Muscle Dysmorphia (MD) and Binge Eating (BE) in males, and Drive for Thinness (DT) and Bulimia (Bu) in females, and their co-variations with BI-related constructs throughout adolescence, 2) Prospectively exploring the unique contribution of BI-related factors and BD in predicting ED outcome, further investigating their reciprocal influences; 3) Exploring multivariate models of ED by testing interaction models among BI-related and personality variables. The PhD thesis presents an introductory chapter providing a framework of prevalence and incidence of EDs in adolescents and vulnerability factors by evidencing the open issues related to sex-specificity. Chapter 2 presents an overview of the longitudinal study, and constructs and measures assessed in the study. Chapter 3 presents an empirical study on how body self-perceptions contribute to predict within-person changes in adolescent sex-specific ED behaviours and attitudes across 1-yr. With the aim of investigating more in deep the multi-facet and somehow ubiquitous construct of BI, Chapter 4 explored BI-factor structure by conducting a confirmatory factor analysis on all the body-related measures herein involved, across 5 waves, further testing for factorial invariance across gender and longitudinal invariance, across time. Chapter 5 represents an empirical contribution to prospectively inspect the unique impact of BI-related factors and BD on sex-specific ED outcomes. Chapter 6 aimed at further investigating the BI-ED association by including personality variables, as potential unique predictors as well as moderators. Results provided some original contributions, extending BI and ED research, as follows: 1) ED outcomes were moderately stable across 1 year with a general intra-individual attenuating trajectory across a 2-year time span, 2) Individual changes in BE and MD in boys co-varied with their actual body-related self-perceptions across one-year, and actual body shape and weight perception predicted DT in girls, along with their desired thin ideal body at intra- and inter-individual levels, 3) The support for the Cash’s 2-factor model of BI among non-clinical adolescents, 4) Meaningful differences in the predictive validity of BI-related domains and BD for sex-specific ED symptoms, lastly 5) Individual differences in personality and emotion regulation aspects were unique predictors of EDs.