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7-07-2015, 07:23

Etiology and Epidemiology

Although the etiology of anorexia nervosa is an area of intense investigation, researchers have yet to reach a consensus about the origin of the disorder. The most sophisticated thinking on the subject regards anorexia nervosa as a multidetermined disorder that involves an interplay of biological, psychological, and cultural factors. Advocates of this model view these three etiological factors as reciprocal and interactive and believe it is simplistic to isolate one component as the single underlying cause of the disorder (Garfinkel and Garner 1982;Brumberg 1988).

Joan Brumberg (1988) has developed a multidetermined etiological model based on a two-staged conceptualization of anorexia nervosa that delineates the relative impact of sociocultural influences and individual biological and psychological variables in precipitating the disorder. In the first stage - the “recruitment” phase of the illness - sociocultural factors play the dominant role. During this period, cultural assumptions that associate thinness with female beauty lead certain women into a pattern of chronic dieting. Indeed, research on the sociocultural causes of anorexia nervosa has linked the increased incidence of anorexia nervosa and other eating disorders with the tremendous cultural attention given to dieting and food, increasingly thinner standards of beauty, and the fitness movement (Schwartz, Thompson, and Johnson 1982; Chernin 1985; Orbach 1986; Bordo 1993). Yet sociocultural variables alone cannot explain why some women but not others move from chronic dieting to anorexia nervosa. Therefore, other individual factors must be implicated in the final development of the illness.

Brumberg’s model of anorexia nervosa relies on a second stage - career or acclimation - to correct the shortcomings of sociocultural explanations of the disorder. During the career phase, specific biological and psychological features determine which individuals develop the full-blown psychopathology of anorexia nervosa. In order to explain the transition between the recruitment and career phases of anorexia nervosa, Brumberg relies on recent research in the biological and social sciences, which has sought to uncover the unique physiological and psychological characteristics of anorexic patients.

Since the early 1900s, a number of different endocrinological and neurological abnormalities have been postulated as underlying biological causes of anorexia nervosa: hormonal imbalance, dysfunction in the satiety center of the hypothalamus, lesions in the limbic system of the brain, and irregular output of vasopressin and gonadotropin (Herzog and Copeland 1985). The search for a biomedical cause of anorexia nervosa is made difficult, however, by the fact that chronic starvation itself produces extensive changes in hypothalamic and metabolic function. Researchers in this area have yet to find a common biological characteristic of the anorexic population that is unmistakably a cause rather than a consequence of extreme weight loss and malnutrition (Brumberg 1988).

A more satisfactory explanation of the biological factors that contribute to the “career” phase of anorexia nervosa is the “addiction to starvation” model proffered by the British psychiatrists George I. Szmukler and Digby Tantum (1984). According to Szmukler and Tantum, patients with fully developed anorexia nervosa are physically and psychologically dependent on the state of starvation. Much like alcoholics and other substance abusers, anorectics find something gratifying or tension-relieving about the state of starvation and possess a specific physiological substrate that makes them more susceptible to starvation dependence than individuals who merely engage in chronic dieting. Szmukler and Tantum add, however, that starvation dependence is not the total explanation of anorexia nervosa. Rather, they believe that starvation dependence acts in conjunction with a range of sociocultural, psychological, and familial factors that encourage certain individuals to use anorexic behavior as a means of expressing personal anguish.

Current psychological models of anorexia nervosa fall into three basic categories: psychoanalytic, family systems, and social psychology. In both the psychoanalytic and family systems models, anorexia nervosa is seen as a pathological response to the developmental crisis of adolescence. Orthodox psychoanalysts, drawing on the work of Sigmund Freud, view the anorectic as a girl who fears adult womanhood and who associates eating with oral impregnation (Brumberg 1988). Family systems theory, however, offers a more complex explanation of the relationship between adolescence and anorexia nervosa. On the basis of clinical work with anorectics and their families, family systems therapists have found that the majority of anorexic patients are “enmeshed,” meaning that the normal process of individuation is blocked by extreme parental overprotectiveness, control, and rigidity. Anorexia nervosa is therefore seen as a form of adolescent rebellion against parental authority (Min-uchin, Rosman, and Baker 1978; Bruch 1988).

Research in social psychology and the field of personality has devised several psychological tests to distinguish the psychological characteristics of anorectics from others in their age-group. One study has shown that although many of the psychological traits of anorectics and other women are indistinguishable, anorectics display a markedly higher degree of ineffectiveness and lower amount of self-esteem. Other studies have proposed that anorectics have actual cognitive problems with body imaging; still others suggest a relationship between anorexia nervosa and sex-role socialization (Garfinkel and Garner 1982).

Some researchers have attempted to fit anorexia nervosa within other established psychiatric categories such as affective disorders and obsessional neurosis. Many anorectics, in fact, display behavior patterns associated with obsessive-compulsive disorders: perfectionism, excessive orderliness and cleanliness, meticulous attention to detail, and selfrighteousness. This correlation has led a number of researchers to suggest that anorexia nervosa is itself a form of obsessive-compulsive behavior (Rothenberg

1986). Depressive symptoms are also commonly seen in many patients with anorexia nervosa. Various family, genetic, and endocrine studies have found a correlation between eating disorders and depression. However, the association between anorexia nervosa and other psychiatric disorders remains controversial (Garfinkel and Garner 1982; Herzog and Copeland 1985).



 

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