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Book Title: Treating and Preventing Adolescent Mental Health Disorders
> pp. [255]-[259]
UNDEFINED: AUTHORS
Treating and Preventing Adolescent Mental Health Disorders
Print ISBN 9780195173642, 2005
pp. [255]-[259]
Part IV
Eating Disorders
COMMISSION ON ADOLESCENT EATING DISORDERS
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B. Timothy Walsh, Commission Chair
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We acknowledge the assistance of Robyn Sysko, M.S., Meghan L. Butryn, M.S., Eric B. Chesley, D.O., Michael P. Levine, Ph.D., and Marion P. Russell, M.D.
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CHAPTER 13 Defining Eating Disorders
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The wide range of human food preferences and of human practices surrounding food preparation and consumption makes the definition of an eating disorder challenging. This challenge is amplified by the fact that dramatic changes occur in energy requirements during adolescence for supporting normal growth and development. For example, between ages 9 and 19, the estimated caloric requirements for girls increases by almost 50% and those for boys, by 80% (Committee on Dietary Reference Intakes, 2002). In addition, dieting related to self-perceived weight status is now extremely common among adolescents (Strauss, 1999). These and other factors provide a fertile environment for the development of disordered eating, yet researchers have paid surprisingly little attention to the task of defining an eating disorder. The most widely used definitions of eating disorders are those provided by the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV, 2000). Only two distinct syndromes, anorexia nervosa and bulimia nervosa, are described in DSM-IV. A residual category, eating disorder not otherwise specified (EDNOS), is provided for all other disorders of eating. A prominent example within the EDNOS category is binge eating disorder, and tentative criteria for binge eating disorder are presented in an appendix in DSM-IV. As is described in more detail below, it appears that most adolescents and adults who present for treatment of an eating disorder do not meet full criteria for either of the two formally defined syndromes and are therefore classified as having an EDNOS. Precisely how to characterize and subdivide this large heterogeneous group is a significant problem for the field. It should also be noted that the state of being overweight or obese is not considered an eating disorder. The presence of excess body fat is viewed in the DSM-IV system as a general medical problem, not a mental disorder. The relationship between obesity and eating disorders, especially binge eating disorder, is a topic of considerable interest. Although most eating disorders begin in adolescence, surprisingly little research has focused on this age range. The ability to make firm treat
ment recommendations for adolescent patients is thus severely limited. In the chapters that follow, our current knowledge of the definition, treatment, and prevention of eating disorders will be reviewed. Chapter 13 includes the etiology of eating disorders; the diagnostic criteria for anorexia nervosa and bulimia nervosa and assessment of how well these criteria apply to adolescents; the demographics and prevalence of eating disorders among adolescents; issues of comorbidity, outcome, and diagnostic migration for adolescents with eating disorders; and the medical complications of anorexia nervosa and bulimia nervosa. Chapter 14 describes psychological and pharmacological treatments for adolescents with eating disorders, and studies of relapse prevention in which psychological or pharmacological interventions are used. Chapter 15 addresses the risk factors for the development of anorexia nervosa and bulimia nervosa, the relationship between treatment of obesity and the development of eating disorders, and prevention. Chapter 16 suggests promising directions for future study in this field.
ETIOLOGY OF EATING DISORDERS
A variety of biological, environmental, and psychosocial factors are associated with the development of an eating disorder, thus such factors may play a causative role in their evolution. However, as is discussed in greater detail in Chapter 15, there is no conclusive evidence that any characteristic or event is specifically associated with the development of anorexia nervosa or bulimia nervosa. Both of these disorders affect primarily women and usually begin around the time of or soon after puberty, thus developmental factors may play a crucial role in the onset of eating disorders. It is not clear, however, whether biological changes that accompany adolescence, psychological changes, or an interaction between the two types of phenomena account for the occurrence of eating disorders. Social factors may also influence the development of eating disorders among adolescents, as adolescents may model overconcern with body shape and weight,
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dieting, or binge eating behavior observed among peers. This behavior suggests that contagion may play a role in the development of eating disturbances, although this phenomenon has received little study. Because these disorders are described primarily in developed countries, Western influence may play an important role, but precisely how cultural factors interact with other phenomena in the development of these disorders is not well understood. Evidence for the impact of Western culture, specifically the influence of mass media, was found in a naturalistic study of adolescents in Fiji, where increased rates of body image and eating disturbances were observed following the introduction of Western media (Becker, Burwell, Gilman, Herzog, & Hamburg, 2002). An experimental study found that exposure to images of the cultural thin-ideal, such as those in fashion magazines, were associated with an increase in negative affect among vulnerable adolescents who reported increased perceived pressure to be thin and body dissatisfaction (Stice, Spangler, & Agras, 2001). There is little question that psychological distress is common within the families of adolescents with serious eating disorders, but it is not clear to what degree such disturbances precede rather than follow development of the eating disorder. There is growing evidence that genetic influences contribute to an individual's vulnerability to develop an eating disorder, but genes specifically linked to the development of anorexia nervosa or bulimia nervosa have not been identified, and it is uncertain how genetic influences may operate to influence the risk of a disorder. In short, despite extensive information about the clinical characteristics of eating disorders and much discussion of potential causes, solid knowledge of the etiology of eating disorders is elusive. In addition, it is likely that different factors contribute to the onset and maintenance of eating disorders. If risk and maintenance factors are distinct, then prevention efforts and treatment interventions likely need to be aimed at somewhat different targets and, potentially, at different populations. However, there is currently insufficient evidence to differentiate with confi
dence those factors that increase the risk of developing an eating disorder from those that perpetuate the disorder once it has begun. The lack of knowledge about such issues clearly limits the development of more effective prevention and treatment interventions.
DIAGNOSTIC CRITERIA FOR EATING DISORDERS
Diagnostic Criteria for Anorexia Nervosa
The most widely used diagnostic criteria for anorexia nervosa are those of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM-IV, 1994a). The DSM-IV diagnostic system is based on a practical foundation and aims to (1) facilitate meaningful communication among clinicians, (2) aid replication of research findings, (3) gauge treatment efficacy by means of carefully defined criteria, and (4) foster further elucidation of the disorder under investigation. The specific DSM-IV criteria for anorexia nervosa are listed in Table 13.1. None of the criteria in the DSM-IV diagnosis of anorexia nervosa is perfect, and further refinement of the criteria is needed. The World Health Organization's 10th Revision of the International Classification of Diseases and Related Health Problems (ICD-10, 1990) also provides diagnostic criteria similar to those of the DSM-IV for eating disorders. However, there are sufficient differences between the two criteria sets that the populations defined are not identical. In this section we will focus on the DSM-IV criteria, as they are widely employed in the research literature. The first criterion deals with weight loss and would seem to be noncontroversial; however, there is no consensus on how weight loss should be calculated, especially during adolescence. Some investigators emphasize the amount lost from an original baseline, and others emphasize weight loss below a normal weight for age and height. The term refusal in the first criterion is also problematic, because it implies a voluntary decision not to eat. In anorexia nervosa, dieting behavior often has an obsessive quality and is difficult for
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doi:10.1093/9780195173642.003.0014
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