Anorexia Nervosa and Bulimia Nervosa
Angela S. Guarda
Alain Joffe
I. Description of the problem. Anorexia nervosa and bulimia are clinical syndromes belonging to a spectrum of conditions best understood as disorders of dieting behavior. The two key characteristics common to both diagnoses are (1) morbid fear of fatness coupled with (2) a disturbance in eating habits comprising one or more behaviors concerned with the consumption or disposal of ingested calories. These behaviors include restricting intake, binge eating, excessive exercise, self-induced vomiting, and/or laxative/diuretic/diet pill abuse. The main distinction between anorexia nervosa and bulimia is ultimately weight, with anorexia being defined by underweight.
Patients with anorexia nervosa have a body weight that is at least 15% below ideal body weight or fail to gain the amount of weight normally expected during the pubertal growth spurt. The term anorexia nervosa is a misnomer, since it implies lack of appetite, which is not a symptom of this condition. Although patients may deny hunger in their attempts to rationalize their dieting behavior, they are constantly preoccupied with thoughts about food and weight. Hypothalamic amenorrhea is also a prominent finding and a consequence of starvation. The applicability of this criterion to younger adolescents who may have not yet achieved menarche or who normally have irregular periods is problematic. Recent data suggest that the presence or absence of amenorrhea does not correlate with severity or prognosis and is not a useful diagnostic criterion. Besides restricting calories and exercising excessively, a subset of anorectics also binge and may vomit or abuse laxatives and diuretics. This purging anorectic subgroup tends to have a worse prognosis and is at higher risk of morbidity.
All patients with bulimia nervosa engage in binge eating, characterized by the ingestion over a 2-hour period of an amount of food that is distinctly greater than the amount most individuals would consume under similar circumstances. These binge eating episodes are accompanied by feelings of guilt and lack of control. Patients with bulimia nervosa are further subdivided according to whether or not they purge in an attempt to prevent weight gain. Purging behaviors include self-induced vomiting or use of laxatives, diuretics, or enemas. Patients with bulimia who do not purge alternate periods of bingeing with severe dietary restriction and/or excessive exercise.
A. Epidemiology.
It is estimated that up to 1% of young females may have anorexia nervosa. Adolescent onset between the ages of 12-18 years is found in 50% of cases.
Approximately 2%-3% of late adolescent and young adult females meet psychiatric diagnostic criteria for bulimia nervosa, with age of onset (approximately 18 years) being slightly older than that for anorexia. A brief period of anorexia nervosa often precedes the onset of bulimia and bingeing behavior with associated weight gain.
Males account for at least 10% of individuals with eating disorders.
Both disorders are seen across all racial, ethnic, and socioeconomic groups. Overall, however, higher rates of eating disorders characterized by restricting and low weight are seen in Caucasian women and higher rates of bingeing and high weight are seen amongst African American women.
B. Genetics.
1. The concordance rate for anorexia nervosa among monozygotic twins is 55% (vs. 7% for dizygotic pairs), suggesting a genetic basis for this syndrome. First-degree relatives of probands are eight times more likely to develop anorexia than are first-degree relatives of healthy controls. The heritability of anorexia nervosa is estimated to be 33%-84%.
2. The concordance rate for monozygotic twins with bulimia (22.9%) is higher than that for dizygotic pairs (8.7%). The heritability of bulimia nervosa is estimated to be 28%-83%. This is high for a psychiatric condition and indicates that individual genetic vulnerability to an eating disorder is a significant predisposing factor.
C. Etiology. There is no single cause for an eating disorder. Factors that may precipitate its onset or contribute to sustaining an eating disorder are the following:
1. Sociocultural. Our society places a high premium on being thin, especially for women. Thinness is often equated, implicitly or explicitly, with success, attractiveness, and self-control. Not surprisingly, women in professions in which thinness is prized, such as models or ballet dancers, have higher rates of eating disorders.
2. Physiologic. During female puberty, there is a widening of the hips and increased deposition of adipose tissue. These normal changes run counter to pervasive sociocultural pressures for thinness that target female adolescents. This may lead to a preoccupation with weight and a dissatisfaction with one’s emerging body shape. The preponderance of affected females versus males also suggests that the estrogenic hormonal milieu may play a role in the onset of eating disorders.
Patients with anorexia nervosa and/or bulimia nervosa have been shown to have multiple metabolic, hormonal, and neurotransmitter abnormalities. However, most of the abnormalities result from starvation or from the purging behaviors associated with eating disorders, thereby precluding a straightforward cause and effect relationship from being established. Some of these secondary abnormalities, however, for example, delayed gastric emptying or preoccupation with food secondary to starvation, are believed to contribute to sustaining the disordered eating behavior.
3. Developmental. Predisposing adolescents to the development of eating disorders are such temperamental or personality factors as being introverted, perfectionist, selfcritical, or eager to please. Patients who primarily restrict calories tend to be riskavoidant. In contrast, those who binge and purge may be self-injurious or display impulsive behaviors such as substance abuse, sexual promiscuity, and shoplifting.
Adolescence is a time of great physiological, psychological, and sociocultural change. Adapting to a markedly changed body, developing a personal and sexual identity, and separation from parents are all important developmental tasks. At this time, adolescents who are otherwise vulnerable to the development of an eating disorder are particularly sensitive to comments about being too fat and to media images that portray thinness as the ideal of beauty, sexual attractiveness, and selfcontrol.
4. Familial. Families of patients with eating disorders have been characterized as either hostile and chaotic or overly enmeshed and rigid. However, ongoing research indicates that many characteristics associated with families of patients with eating disorder are also typical of families of chronically ill children, suggesting that these patterns of interaction are a consequence rather than a cause of the illness.
II. Making the diagnosis.
A. Signs and symptoms. Young women rarely disclose an eating disorder to their primary care clinician. Just as patients with anorexia deny hunger as they pursue the ideal body shape, so too will they ignore or cover up various manifestations of their illness. They may wear bulky clothing in an attempt to hide their weight loss, deny fear of fatness, or be quite secretive about their bingeing, vomiting, or abuse of laxatives or diuretics. Hence, the clinician must maintain a high index of suspicion and gently but firmly pursue the diagnosis when symptoms suggest or are consistent with an eating disorder.
The signs and symptoms associated with eating disorders are highlighted in Table 22-1. What is apparent on physical examination is a function of whether the patient is starving herself to the point of being significantly underweight and/or whether she uses purging techniques to control her weight. Girls who develop anorexia nervosa prior to the onset of or early in puberty will present with failure to gain the weight normally expected with physical maturation or with delayed onset of secondary sexual characteristics or primary amenorrhea.
B. Differential diagnosis. In developing a differential diagnosis, clinicians should remember that patients with illnesses whose signs and symptoms are similar to anorexia nervosa and bulimia generally indicate discomfort with these manifestations and do not have a persistent and overriding concern with body shape and weight. While they may, initially, be pleased with a limited amount of unexpected weight loss, they become alarmed as their weight continues to fall. They do not exclusively limit fat and calories and concerns about weight and body shape do not preoccupy them to the exclusion of all else. Diseases that can mimic these disorders are listed in Table 22-2. A thorough history that addresses all aspects of an adolescent’s life (HEADSS: Homelife, Education, Activities/Affect (e.g., mood), Drug use, Sexuality/sexual behaviors, and Suicidal thoughts/actions), a careful physical examination and perhaps a few screening laboratory tests (such as an erythrocyte sedimentation rate (ESR), stool for occult blood, and thyroid-stimulating hormone (TSH)) are generally sufficient to exclude these diagnoses.
Table 22-1. Signs and symptoms of eating disorders
Associated with starvation
Associated with purging
General
Hyperactivity or lethargy
Irritability
Sleep problems
Dizziness, confusion
Syncope
Hypothermia
Dizziness, syncope
Confusion
Skin
Subcutaneous fat loss
Dry, brittle hair or loss of hair
Lanugo hair on torso or face
Yellow skin
Ulcerations, scars, or calluses on back of hand over knuckles
Perioral acne
Oral
Dental caries
Enamel erosion or discoloration of teeth (lingual surface)
Parotid gland hypertrophy
Cardiovascular
Hypotension
Bradycardia
Arrhythmias
Gastrointestinal
Constipation
Epigastric tenderness
Gastroesophageal reflux
Decreased bowel sounds
Abdominal distension
Ileus
Neuromuscular
Muscle weakness/wasting
Muscle weakness, paresthesias
Extremities
Decreased deep tendon reflexes cold, mottled hands and feet
Decreased deep tendon reflexes
Genitourinary
Thin, pale, dry, atrophic vaginal mucosa, amenorrhea, low libido
Edema of feet
Musculoskeletal
Osteopenia/fractures
Note: Patients who are malnourished and engaged in purging behaviors will display signs and symptoms from both columns.
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