AN INVESTIGATION INTO THE GENETIC AND ENVIRONMENTAL INFLUENCES LEADING TO THE DEVELOPMENT OF EATING DISORDERS IN ADOLESCENTS

CHAPTER ONE INTRODUCTION 1.1 Background of the Study Eating disorders (EDs) are complex and severe mental health conditions characterized by persistent disturbances in eating patterns and distorted perceptions of body image. These disorders significantly impair both physical well-being and social functioning (American Psychiatric Association [APA], 2013). Common types of eating disorders include anorexia nervosa, bulimia nervosa, and binge-eating disorder. These typically begin during adolescence—a critical developmental stage marked by rapid biological, psychological, and social changes (Stice et al., 2015). During this period, young people often become increasingly concerned with body image and experience heightened peer influence, both of which can contribute to the development of disordered eating behaviours (Rodgers et al., 2020). The prevalence of eating disorders among adolescents has been rising steadily. Recent studies show that more than 2.7% of teenagers globally are diagnosed with a clinical eating disorder each year, while many others exhibit subclinical symptoms that severely affect their quality of life (Qian et al., 2023). In the United States, it is estimated that up to 10% of adolescents may meet the diagnostic criteria for an eating disorder before they reach adulthood, highlighting the urgency of addressing this growing public health concern (Lipson & Sonneville, 2017). This upward trend underscores the importance of understanding the diverse factors—particularly during adolescence—that contribute to the onset of these disorders. Genetics plays a significant role in predisposing individuals to eating disorders. Twin and family studies have estimated the heritability of these disorders to range between 50% and 83% (Culbert, Racine, & Klump, 2015). A family history of eating disorders, mood disturbances, or anxiety disorders increases the likelihood of disordered eating patterns (Trace et al., 2016). Specific genetic markers, particularly those that affect the serotonin and dopamine systems, are associated with an increased risk by influencing mood regulation, appetite control, and the brain’s reward pathways (Baker et al., 2020). Nonetheless, genetic susceptibility alone is not sufficient to cause eating disorders—interactions with environmental factors are also essential. Environmental influences—including societal, familial, and personal factors—play a substantial role in the development of eating disorders. The societal glorification of thinness, especially in Western cultures, contributes significantly to body dissatisfaction and the adoption of unhealthy weight control practices among adolescents (Rodgers et al., 2020). Exposure to idealized beauty standards via mainstream and social media intensifies these pressures, fostering negative body image and the internalization of thin-ideal norms (Grabe, Ward, & Hyde, 2018). Family attitudes, especially those related to dieting and weight, can also influence adolescents’ body image and eating behaviours (Tylka & Kroon Van Diest, 2015). The interaction between genetic predisposition and environmental exposure—referred to as gene-environment interaction—is central to understanding the development of eating disorders. Adolescents genetically prone to mood instability may be especially vulnerable to external stressors such as peer criticism related to appearance, which can trigger disordered eating (Culbert et al., 2015). Early life adversity, including trauma or abuse, is also known to elevate the risk of eating disorders, particularly among individuals with a genetic vulnerability to emotional dysregulation (Troop & Treasure, 2016). Additionally, adolescence is a time of considerable neurodevelopmental changes. These include alterations in brain regions responsible for processing rewards, regulating impulses, and managing emotions—all of which are implicated in the development of eating disorders (Stice & Burger, 2019). Hormonal changes during puberty, particularly in females, further increase susceptibility to body image disturbances and problematic eating behaviours (Klump et al., 2015). Some research suggests that genetic factors may influence how the brain responds to environmental stressors, thereby increasing the risk of eating disorders in certain individuals (Bulik et al., 2017). Despite advances in understanding these disorders, there remains a lack of clarity regarding how genetic and environmental factors interact during adolescence to shape vulnerability. Consequently, this study aims to explore the genetic and environmental determinants that contribute to the onset of eating disorders during this formative stage of life. 1.2 Statement of the Problem Eating disorders are multifaceted mental health conditions influenced by both genetic and environmental factors. Adolescence is a particularly vulnerable phase for their onset due to intense physical, emotional, and social changes (Stice et al., 2015). While genetic predispositions can increase risk, environmental conditions such as family dynamics, peer influence, and cultural expectations play an equally vital role (Culbert, Racine, & Klump, 2015). Despite growing awareness, the number of adolescents affected by eating disorders continues to climb, with recent figures indicating that over 2.7% of teens worldwide are affected annually by clinically diagnosed eating disorders (Qian et al., 2023). There remains a critical gap in our understanding of how specific genetic vulnerabilities interact with environmental stressors to influence the likelihood of developing eating disorders during adolescence. For instance, while a family history of psychiatric disorders—particularly mood-related conditions—is known to contribute to genetic risk, the mechanisms underlying this association are not fully understood (Trace et al., 2015). Likewise, environmental exposures such as social media, which often promotes unattainable body ideals, have been linked to increasing levels of body dissatisfaction and disordered eating among adolescents (Rodgers et al., 2020). However, how these external factors amplify existing genetic vulnerabilities remains insufficiently explored. This study, therefore, aims to investigate how genetic and environmental influences together contribute to the onset of eating disorders among adolescents. 1.3 Objective of the Study The primary objective of this research is to examine the genetic and environmental contributors to the development of eating disorders among adolescents. The specific objectives are as follows: i. To determine the prevalence of eating disorders among adolescents. ii. To identify the most common types of eating disorders affecting adolescents during their developmental years. iii. To investigate the genetic factors that increase adolescents’ vulnerability to eating disorders. iv. To explore environmental influences that contribute to the onset of eating disorders in adolescents. 1.4 Research Questions To guide this study, the following research questions are proposed: i. What is the prevalence of eating disorders among adolescents? ii. What are the most common types of eating disorders that manifest during adolescence? iii. What genetic factors heighten susceptibility to eating disorders in adolescents? iv. How do environmental influences contribute to the development of eating disorders in adolescents? 1.5 Significance of the Study The findings of this study are expected to be of substantial value to the Ministry of Health. Given the profound physical, psychological, and social consequences of eating disorders, this research can support public health strategies aimed at reducing their prevalence and mitigating their impact. By identifying modifiable risk factors, the study could inform interventions that reduce the incidence of eating disorders and associated complications among adolescents. Additionally, the study will contribute to the academic community by enriching the body of literature on the topic. It will also serve as a reference for future researchers and enhance the resources available in academic libraries. 1.6 Scope of the Study This research focuses specifically on the genetic and environmental factors that contribute to the development of eating disorders in adolescents. Empirically, the study will assess the prevalence of eating disorders, identify the most common types occurring during adolescence, and explore both genetic and environmental contributors to these conditions. Geographically, the research is confined to adolescents attending junior secondary schools in Burutu Local Government Area, Delta State. 1.7 Limitations of the Study As with any research endeavour, this study faced several challenges. Notable limitations include: Time Constraints: Balancing this research project with other academic responsibilities, such as attending lectures and participating in coursework, posed scheduling difficulties for the researcher. Financial Constraints: The study incurred costs related to data collection, printing, typesetting, and sourcing relevant materials, all of which strained the researcher’s budget. Limited Access to Materials: Locating appropriate and recent literature on the topic proved challenging, due to the specificity and sensitivity of the subject matter. 1.8 Definition of Terms Eating Disorders (EDs): A group of psychological conditions marked by abnormal eating behaviours, distorted body image, and intense concerns about weight and shape, often resulting in serious health consequences. Examples include anorexia nervosa, bulimia nervosa, and binge-eating disorder. Genetic Factors: Inherited traits passed through genes that can predispose individuals to mental health disorders, including eating disorders. These may involve gene variants that affect mood, emotional regulation, and appetite. Environmental Factors: External influences such as media, family, peers, and cultural norms that shape behaviour and perceptions, often contributing to the development of disordered eating. Adolescents: Young individuals aged 10 to 19 undergoing major physical, emotional, and social changes, making them especially vulnerable to developing eating disorders (World Health Organization). Gene-Environment Interaction: The interplay between genetic predispositions and environmental factors that together influence the development of conditions like eating disorders. Body Dissatisfaction: Negative evaluation of one’s own body, often stemming from the internalization of societal beauty ideals, and a key risk factor for eating disorders—particularly in adolescents.