Eating Disorders

I. Anorexia Nervosa

Anorexia nervosa is a syndrome characterized by three essential criteria: (1) a self-induced starvation to a significant degree, (2) a relentless drive for thinness or a morbid fear of fatness, and (3) the presence of medical signs and symptoms resulting from starvation. It is often associated with disturbances of body image—the perception that one is distressingly large despite obvious thinness.

A. Epidemiology.

The most common age of onset is between 14 and 18 years. Anorexia nervosa is estimated to occur in about 0.5% to 1% of adolescent girls. It occurs 10 to 20 times more often in females than in males. The prevalence of young women with some symptoms of anorexia nervosa who do not meet the diagnostic criteria is estimated to be close to 5%. It seems to be most frequent in developed countries, and it may be seen with greatest frequency among young women in professions that require thinness, such as modeling and ballet.

B. Etiology.

Biological, social, and psychological factors are implicated in the causes of anorexia nervosa. Some evidence points to higher concordance rates in monozygotic twins than in dizygotic twins. Major mood disorders are more common in family members than in the general population.

Biological factors. Starvation results in many biochemical changes, some of which are also present in depression, such as hypercortisolemia and nonsuppression by dexamethasone. An increase in familial depression, alcohol dependence, or eating disorders has been noted. Some evidence of increased anorexia nervosa in sisters has also been noted. Neurobiologically, a reduction in 3-methoxy-4-hydroxyphenylglycol (MHPG) in urine and cerebrospinal fluid (CSF) suggests lessened norepinephrine turnover and activity. Endogenous opioid activity appears lessened as a consequence of starvation. In one positron emission tomography (PET) study, caudate nucleus metabolism was higher during the anorectic state than after weight gain. Magnetic resonance imaging (MRI) may show volume deficits of gray matter during illness, which may persist during recovery. A genetic predisposition may be a factor.

Social factors. Patients with anorexia nervosa find support for their practices in society’s emphasis on thinness and exercise. Families of children who present with eating disorders, especially binge-eating or purging subtypes, may exhibit high levels of hostility, chaos, and isolation and low levels of nurturance and empathy. Vocational and avocational interests interact with other vulnerability factors to increase the probability of developing eating disorders (i.e., ballet in young women and wrestling in high school boys).

Table 19-1 DSM-IV-TR Diagnostic Criteria for Anorexia Nervosa

Refusal to maintain body weight at or above a minimally normal weight for age and height (e.g., weight loss leading to maintenance of body weight less than 85% of that expected; or failure to make expected weight gain during period of growth, leading to body weight less than 85% of that expected).
Intense fear of gaining weight or becoming fat, even though underweight.
Disturbance in the way in which one’s body weight or shape is experienced, undue influence of body weight or shape on self-evaluation, or denial of the seriousness of the current low body weight.
In postmenarchal females, amenorrhea, i.e., the absence of at least three consecutive menstrual cycles. (A woman is considered to have amenorrhea if her periods occur only following hormone, e.g., estrogen, administration.)

Specify type:

Restricting type: during the current episode of anorexia nervosa, the person has not regularly engaged in binge-eating or purging behavior (i.e., self-induced vomiting or the misuse of laxatives, diuretics, or enemas)
Binge-eating/purging type: during the current episode of anorexia nervosa, the person has regularly engaged in binge-eating or purging behavior (i.e., self-induced vomiting or the misuse of laxatives, diuretics, or enemas)

From American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, 4th ed. Text rev. Washington, DC: American Psychiatric Association; 2000, with permission.

Psychological and psychodynamic factors. Patients with the disorder substitute their preoccupations, which are similar to obsessions, with eating and weight gain for other, normal adolescent pursuits. These patients typically lack a sense of autonomy and self-hood.

C. Diagnosis and clinical features.

The onset of anorexia nervosa usually occurs between the ages of 10 and 30 years. It is present when (1) an individual voluntarily reduces and maintains an unhealthy degree of weight loss or fails to gain weight proportional to growth; (2) an individual experiences an intense fear of becoming fat, has a relentless drive for thinness despite obvious medical starvation, or both; (3) an individual experiences significant starvation-related medical symptomatology, often, but not exclusively, abnormal reproductive hormone functioning, but also hypothermia, bradycardia, orthostasis, and severely reduced body fat stores; and (4) the behaviors and psychopathology are present for at least 3 months (Table 19-1). Obsessive–compulsive behavior, depression, and anxiety are other psychiatric symptoms of anorexia nervosa most frequently noted in the literature. Poor sexual adjustment is frequently described in patients with the disorder.

D. Subtypes

Restricting type (no binge eating). Present in approximately 50% of cases. Food intake is highly restricted (usually with attempts to consume fewer than 300 to 500 calories per day and no fat grams), and the patient may be relentlessly and compulsively overactive, with overuse athletic injuries. Persons with restricting anorexia nervosa often have obsessive–compulsive traits with respect to food and other matters.
Binge-eating/purging type. Patients alternate attempts at rigorous dieting with intermittent binge or purge episodes, with the binges, if present, being either subjective (more than the patient intended, or because of social pressure, but not enormous) or objective. Purging represents a secondary compensation for the unwanted calories, most often accomplished by self-induced vomiting, frequently by laxative abuse, less frequently by diuretics, and occasionally with emetics. The suicide rate is higher than in those with the restricting type.

E. Pathology and laboratory examination.

A complete blood count often reveals leukopenia with a relative lymphocytosis in emaciated patients with anorexia nervosa. If binge eating and purging are present, serum electrolyte determination reveals hypokalemic alkalosis. Fasting serum glucose concentrations are often low during the emaciated phase, and serum salivary amylase concentrations are often elevated if the patient is vomiting. The ECG may show ST-segment and T-wave changes, which are usually secondary to electrolyte disturbances; emaciated patients have hypotension and bradycardia.

F. Differential diagnosis

Medical conditions and substance use disorders. Medical illness (e.g., cancer, brain tumor, gastrointestinal disorders, drug abuse) that can account for weight loss.
Depressive disorder. Depressive disorders and anorexia nervosa have several features in common, such as depressed feelings, crying spells, sleep disturbance, obsessive ruminations, and occasional suicidal thoughts. However, generally a patient with a depressive disorder has decreased appetite, whereas a patient with anorexia nervosa claims to have normal appetite and feels hungry; only in the severe stages of anorexia nervosa do patients actually have a decreased appetite. Also, in contrast to depressive agitation, the hyperactivity seen in anorexia nervosa is planned and ritualistic. The preoccupation with recipes, the caloric content of foods, and the preparation of gourmet feasts is typical with anorexia nervosa not with depressive disorder. In depressive disorders, patients have no intense fear of obesity or disturbance of body image. Comorbid major depression or dysthymia has been found in 50% of patients with anorexia.
Somatization disorder. Weight loss not as severe; no morbid fear of becoming overweight; amenorrhea unusual.
Schizophrenia. Delusions about food (e.g., patients believe the food to be poisoned). Patients rarely fear becoming obese and are not as hyperactive.
Bulimia nervosa. Patient’s weight loss is seldom more than 15%. Bulimia nervosa develops in 30% to 50% of patients with anorexia nervosa within 2 years of the onset of anorexia.