Bulimia Nervosa Epidemiology and Etiology

Epidemiology

Between 1% and 3% of young adult females in the United States meet the diagnostic criteria for bulimia nervosa. As many as 40% of young adults engage in episodic binge eating but do not meet the diagnostic criteria. Bulimia nervosa occurs in 0.2% of adolescent boys and young adult males and accounts for 10-15% of bulimics identified in community-based studies.

Etiology & Pathogenesis
The cause is not known. The episodic, uncontrolled nature of the eating behaviors has led some investigators to suggest that bulimia may be a variant of complex partial seizure disorder. However, the few electroencephalographic abnormalities reported in patients studied during the testing of this hypothesis did not correlate with treatment response to phenytoin.

The strong association between bulimia nervosa and affective disorders together with the tendency of bulimic behavior to respond to antidepressant medication has led to the hypothesis that the disorder is the result of imbalance in the dopamine, norepinephrine, and serotonin systems in the brain. Some studies have suggested that neuropeptides such as cholecystokinin, which regulate appetite and satiety in the brain, may be abnormal in patients with bulimia nervosa, but the evidence is far from conclusive.

Psychodynamic theories emphasize the symbolic nature of eating binges as representing gratification of sexual and aggressive wishes. Self-deprecation and self-induced vomiting following binges may thus represent guilt-induced self-punishment for fantasized transgressions.

Psychologists have also noted that the binge-vomiting cycle may represent a ritual acceptance and taking in followed by a rejection of symbolic love objects. Bulimia may thus represent an attempt to control the external environment. Patients with bulimia are noted to have low self-esteem, and the vomiting may represent a symbolic purging of bad aspects of the self. Patients with bulimia tend to be overconcerned with body image and often have impaired object relationships that are recapitulated in their eating behaviors.