Eating Disorders - Risk Factors

Causes

There is no single cause for eating disorders. Although concerns about weight and body shape play a role in all eating disorders, the actual cause of these disorders appears to involve many factors, including those that are genetic and neurobiologic, cultural and social, and behavioral and psychologic.

Although much has been written about the roles of families and parenting as causes of eating disorders, there is no solid evidence supporting this claim.

Genetic Factors

Anorexia is eight times more common in people who have relatives with the disorder. Studies of twins show they have a tendency to share specific eating disorders (anorexia nervosa, bulimia nervosa, and obesity). Researchers have identified specific chromosomes that may be associated with bulimia and anorexia.

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Biologic Factors

The body’s hypothalamic-pituitary-adrenal axis (HPA) may be important in eating disorders. This complex system originates in the following regions in the brain:

• Hypothalamus. The hypothalamus is a small structure that plays a role in controlling our behavior, such as eating, sexual behavior and sleeping, and regulates body temperature, hunger and thirst, and secretion of hormones.
• Pituitary gland. The pituitary gland is involved in controlling thyroid functions, the adrenal glands, growth, and sexual maturation.
• Amygdala. This small almond-shaped structure lies deep in the brain and is associated with regulation and control of major emotional activities, including anxiety, depression, aggression, and affection.

Click the icon to see an image of the hypothalamus.

The HPA system releases certain neurotransmitters (chemical messengers in the brain) that regulate stress, mood, and appetite. Abnormalities in the activities of three of them, serotonin, norepinephrine, and dopamine, may play a particularly important role in eating disorders. Serotonin is involved with well-being, anxiety, and appetite (among other traits), and norepinephrine is a stress hormone. Dopamine is involved in reward-seeking behavior. Imbalances with serotonin and dopamine may explain in part why people with anorexia do not experience a sense of pleasure from food and other typical comforts.

Cultural Pressures

The media plays a role in promoting unrealistic expectations for body image and a distorted cultural drive for thinness. At the same time, cheap and high-caloric foods are aggressively marketed. Such messages are contradictory and confusing.

Review Date: 02/18/2011
Reviewed By: David B. Merrill, MD, Assistant Clinical Professor of Psychiatry, Department of Psychiatry, Columbia University Medical Center, New York, NY. Also reviewed by Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital; and David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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