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Anorexia nervosa has been defined as a serious eating disorder primarily affecting young women in their teens and early twenties, that is characterized especially by a pathological fear of weight gain leading to faulty eating patterns, malnutrition, and usually excessive weight loss. Bulimia nervosa has been defined as a serious eating disorder that occurs chiefly in females, characterized by overeating, usually followed by self-induced vomiting or laxative or diuretic abuse, and is often accompanied by guilt and depression.(1) The American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV), includes the diagnosis of eating disorders not otherwise specified (NOS).(2) Individuals with eating disorders in this category manifest symptoms of eating disorders, but do not meet the diagnostic criteria for a specific eating disorder.
Understanding these disorders is difficult due to the array of physiologic, biochemical, developmental, psychological, and psychiatric phenomena associated with them. It is difficult to determine whether some biologic changes are causing the eating disorder, or whether the changes are a result of aberrant eating patterns and eventual starvation.
Abnormalities of the hypothalamic-pituitary-adrenal (HPA), hypothalamic-pituitary-gonadal (HPG), and hypothalamic-pituitary-thyroid (HPT) axes have been described as potential causes of anorexia nervosa.(3) Although many endocrine abnormalities occur in other forms of starvation, the difference is that in anorexia nervosa, the dysfunction may not improve when weight is normalized. The finding of amenorrhea in the majority of females suffering from anorexia nervosa is such an example. Up to 25 percent of females had amenorrhea before the onset of anorexia, and the return of menses lags behind weight normalization. The role of neurotransmitters has also been extensively investigated, particularly serotonin, as it plays an important role in eating. Norepinephrine has a role in the increase or decrease of hunger sensations, and dopamine may play a part in the self-stimulatory behavior of eating binges in the bulimic patient.
The greatest emphasis, however, is placed on psychological and developmental issues in the pathogenesis of eating disorders, especially regarding the role of family. Issues surrounding family separations, losses, and dysfunction may trigger abnormal eating behavior.(3, 4) Whether family-related issues are etiologic for eating disorders remains controversial. It is interesting, however, to note that the prognosis is better in persons with a relatively healthy family environment.(5)
Other groups at risk for the development of eating disorders are those with a history of physical and sexual abuse. Also at risk are athletes, particularly female gymnasts, figure skaters, distance runners, and swimmers. Male wrestlers and body builders are included in this risk category as well.
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