The eating disorders (EDs) Anorexia (AN) and Bulimia Nervosa (BN) are severe psychiatric disorders that most commonly begin during adolescence (APA, 2000; Sullivan, 1995). The teenage years form a critical period of significant changes in both biological and psychosocial development. Neurobiologic and genetic factors have only recently been recognized as contributing to the development of AN and BN, in addition to well-known psychological and environmental factors. This new understanding of the etiology of EDs lays the foundation for a developmental neuroscience perspective in ED research. In this chapter, we describe ED phenotypes and the current knowledge of their neurobiology. Several limitations should be noted: Because women are predominantly affected, research in males has been sparse, and thus this review focuses on the female population. Second, although AN and BN usually begin in adolescence, most available neurobiologic research has studied women above the age of 18 years, and developmental aspects have been largely ignored.
Anorexia Nervosa (AN) is associated with emaciation, intense fear of gaining weight, feeling fat despite being underweight, and amenorrhea for three or more months. About 95% percent of affected individuals are female. A restricting type has been distinguished from a binge-eating/purging type. AN has the highest mortality rate of the psychiatric disorders.
Bulimia Nervosa (BN) is characterized by recurrent binge eating episodes, a loss of control over amount eaten, followed by behaviors to counteract weight gain, such as self-induced vomiting, use of laxatives, or over-exercising. About 90% of BN individuals are females, usually of normal body weight, who are preoccupied with food and weight.
For Binge Eating Disorder (BED), current research criteria (DSM-IV) includes the existence of recurrent binge eating episodes accompanied with a loss of control, similar to BN; however, this disorder lacks the compensatory behavior such as vomiting or over exercising seen in BN. BED patients are usually highly obese and have a high weight fluctuation pattern.