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Eating disorders arise from unique relationships between individual vulnerabilities and environmental factors, said Gary Rodin, M.D., chair of a symposium on the etiology of eating disorders at this year's APA annual meeting in Toronto. The complexity of the interaction of psychology and environment is particularly striking in these disorders, he noted.
Rodin and several other presenters discussed a number of different risk factors for developing eating disorders, including genetics, temperament, environment, trauma, sexual abuse, and disturbances in early attachment with caretakers. Some antedate and increase the risk of onset, others precipitate it, and still others may amplify the severity of a condition or perpetuate it, said Rodin, who is psychiatrist in chief in the department of psychiatry at Toronto Hospital. In addition, he said, conditions such as diabetes may present a particular risk for eating disorders.
Eating disorders are distinguished from the normal dieting, weight, and shape concerns that exist in the population by associated psychological disturbances as well as disordered eating behavior and disturbed body image, Rodin said. At one level they involve core weight and shape concerns and behavioral concerns such as the drive for thinness and binge and purge behaviors. At another level "there are questions of self-evaluation unduly linked to shape and weight, which in fact likely represent a more fundamental disturbance in self-concept," he said. Finally, he added, there is a whole variety of other psychological disturbances, particularly in affect, present in people with eating disorders.
Paul Garfinkel, M.D., president of the Addictions and Mental Health Services Corporation in Toronto, listed early puberty, high body mass index, early onset of dieting, body dissatisfaction, and problems with affect regulation, depression, and impulse control as causes of eating disorders. Early sexual abuse and physical abuse are significant risk factors, too, he said. But "epidemiological data can take us only so far, because early trauma and early abuse, which are three times as common here, have to have some kind of mechanism within the individual. Do they affect helplessness, loathing, or affective regulation?" It is important to study the interaction of epidemiology and individual psychology, he concluded.
Why at this time are dieting and weight preoccupation of such great importance in the Western world, and why do they lead to such significant pathology?, asked Gar-finkel. While the answers to these questions are not known, he listed the following possible causes: emulation of a higher social class where dieting predominates, health consciousness and fears about obesity, which is seen as a moral phenomenon; preoccupation with youth and the desire to remain youthful and thin; overvaluation of a sense of personal control (diet linked to sense of control); and conflicting but dramatic changes in social expectations for women.
In addition, said Garfinkel, society promotes idealization of the thin female form, and many young women succumb to pressures to achieve, please others, and live up to external expectations rather than internal demands, he said. There are strong empirical data that youngsters are dieting more frequently and earlier than ever, noted Garfinkel. One study showed that 40 percent of girls in the United States consider themselves overweight, while only 4 four percent actually are. It also appears that the number of people with anorexia nervosa continues to increase, he said.
Presentations by other panelists illustrated the complexity of the risk factors for eating disorders. Janet deGroot, M.D., staff psychiatrist in the department of psychiatry at Toronto Hospital-Western Division, presented a summary of research on the link between eating disorders and sexual abuse. The number of studies on this subject has burgeoned in the past decade but they reveal highly conflicting findings, she said. In looking at the research and conducting her own, deGroot concluded that the balance of evidence suggests that childhood sexual abuse is a nonspecific risk factor that may contribute to the development of an eating disorder.
Data on the relationship between obesity and eating disorders were more conclusive. According to Allan Kaplan, M.D., director of the Eating Disorders Clinic in the department of psychiatry at Toronto Hospital, obesity has been well established as a significant risk factor for developing an eating disorder. He presented epidemiologic data supporting this (bulimia nervosa and binge eating disorder), and a biopsychosocial risk factor paradigm to postulate mechanisms through which the overweight state predisposes an individual to an eating disorder. He discussed factors such as the genetics of weight control, comorbidity, the effects of dieting and caloric restriction, as well as the psychosocial consequences of obesity.
A link also can exist between being a gay man and having an eating disorder, said another presenter. According to Arnold Andersen, M.D., director of Eating Disorders Programs in the department of psychiatry at the University of Iowa, 20 percent of people with eating disorders are gay men although they represent only 5 percent of the general population. He said that weight and shape norms within the gay community may contribute to the propensity for men to develop eating disorders. Gay men demonstrate more body dissatisfaction and greater desire for thinness than heterosexual men, he noted.
Another possible risk factor for eating disorders is compulsive exercising, said Caroline Davis, Ph.D., an associate professor of psychology in the department of kinesiology and health sciences at York University in Toronto. Davis said that the prevalence of excessive exercise among eating-disordered patients is very high and that high-level exercisers are more weight preoccupied and have a greater drive for thinness than moderate exercisers.
In contrast, the prevalence studies of eating disorders in young women with diabetes have been contradictory and inconclusive due to small sample sizes in the age of risk and variable assessment tools, said Rodin. Yet it has been established, he added, that one-third of adolescent girls with diabetes deliberately omit taking insulin to prevent weight gain, and up to 25 percent suffer from clinical or subclinical eating disorders.