Anorexia Nervosa

Anorexia Nervosa is a severe eating disorder characterized by low body weight. Anorexia Nervosa is diagnosed when a person’s body weight falls below 85% of the ideal weight for that individual. The weight loss must be due to behavior directed at maintaining low weight or achieving a particular body image.

Epidemiology
The point prevalence of Anorexia Nervosa is between 0.5% and 1% in women, and more than 90% of patients with Anorexia Nervosa are women. The prevalence in men is not clear. Average age of onset is 17; onset is rare before puberty or after age 40.
Anorexia Nervosa is more common in industrial societies and higher socioeconomic classes.

Etiology
Eating disorders and their subtypes likely share many common bases of origin. Psychological theories of Anorexia Nervosa remain speculative. Patients with Anorexia Nervosa generally have a high fear of losing control, difficulty with self-esteem, and commonly display"al1 or none” thinking. Although it is not specific to eating disorders, past physical or sexual abuse may be a risk factor. Contemporary theories focus on the need to control one’s body.
Social theories propose that societal opinions, which equate low body weight with attractiveness, drive women to develop eating disorders. Although this fact may be responsible for some cases (e.g., Anorexia Nervosa is more common among dancers and models), historical1y Anorexia Nervosa has been present during periods when societal mores for beauty were different.

Biologic, familial, and genetic data support a biologic and heritable basis for anorexia. Family studies reveal an increased incidence of mood disorders and Anorexia Nervosa in first-degree relatives of patients with Anorexia Nervosa. Twin studies show higher concordance for monozygotic versus dizygotic twins.

Neuroendocrine evidence supporting a biologic contribution to anorexia includes alterations in corticotropin-releasing factor, reduced central nervous system norepinephrine metabolism, and that amenorrhea (caused by decreased luteinizing hormone and follicle-stimulating hormone release) sometimes precedes the onset of Anorexia Nervosa.

Clinical Manifestations
History and Mental Status Examination
DSM-IV criteria for the diagnosis of Anorexia Nervosa include refusal to keep body weight at greater than 85 % of ideal, an intense fear of weight gain, preoccupation with body size and shape, a disproportionate influence of body weight on personal worth, and the denial of the medical risks of low weight. Patients with Anorexia Nervosa generally do not have a loss of appetite; they refuse to eat out of fear of gaining weight. Amenorrhea is also a diagnostic criteria in postmenarchal females (delay of menarche may occur in premenarchal girls). In some cases, amenorrhea precedes the development of Anorexia Nervosa; however, in most cases, it appears to be a consequence of starvation.

Individuals with Anorexia Nervosa commonly exercise intensely to lose weight and alter body shape. Some restrict food intake as a primary method of weight control; others use binging and purging (use of laxatives, enemas, diuretics, or induced vomiting) to control weight.

The behavioral repertoire used to control body weight is used to further classify Anorexia Nervosa into two subtypes: restricting type and binging/ purging type. In the restricting type, the major methods of weight control are food restriction and exercise. In the binging/purging type, food restriction and exercise may be present, but binge eating and subsequent purging behaviors also are present.

The natural course of anorexia is not well understood, but many cases become chronic. The long-term mortality of Anorexia Nervosa secondary to suicide or medical complications is greater than 10%.

Differential Diagnosis
Conditions that can resemble anorexia should be ruled out. These include major depression with loss of appetite and weight, some psychotic disorders where nutrition may not be adequate, body dysmorphic disorder, and a variety of general medical (especially neuroendocrine) conditions. Anorexia Nervosa is differentiated from bulimia nervosa by the presence of low weight in the former.

Management
The management of Anorexia Nervosa is directed at the presenting symptoms. When medical complications are present, these must be carefully treated and followed. If ipecac use to induce vomiting is suspected, ipecac toxicity must be ruled out.

During starvation, psychotherapy is of little value because of the cognitive impairment produced by starvation. When patients are less medically ill, a therapeutic program including supervised meals; weight and electrolyte monitoring; psychoeducation about the illness, starvation, and nutrition; individual psychotherapy, and family therapy can begin. Psychopharmacology management often includes antidepressants, especially the selective serotonin reuptake inhibitors (SSRls) to treat comorbid depression. Psychopharmacologic treatments are used principally to treat any comorbid psychiatric illness and have little or no effect on the anorexia per se.

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