19 October 1998

New Findings Suggest A Biological Cause For Eating Disorders

Researchers at the University of Pittsburgh Medical Center's (UPMC) Western Psychiatric Institute and Clinic have found evidence supporting the possibility that an alteration of brain chemistry contributes to the development of bulimia nervosa and persists even after recovery from the disorder.

The UPMC study, authored by Walter H. Kaye, M.D., professor of psychiatry, appears in the October issue of Archives of General Psychiatry.

Women with bulimia nervosa, when bingeing and purging, are known to have alterations of brain serotonin activity and mood as well as obsessions with perfectionism. Serotonin is a neurotransmitter that helps regulate mood. This study found that these alterations and symptoms persisted after recovery from bulimia nervosa, suggesting that they are not merely a consequence of abnormal eating behaviors. Theoretically, altered serotonin activity could cause anxious and obsessive behaviors and affect the control of appetite and thus contribute to a vulnerability to develop bulimia nervosa.

"The development of an eating disorder is often attributed to the effects of our cultural environment, such as the mass media, which places a heavy emphasis on slimness. But while all women are exposed to these cultural mores, only a small percentage develop an eating disorder. Our study may have identified a biological risk factor that plays a part in deciding who develops a disorder," explained Dr. Kaye. "This study is important because it will help shift focus to the underlying causes of bulimia nervosa so that we can develop better treatments in the future and possibly identify people at risk for the disorder before it occurs."

Bulimia nervosa affects about 1 to 3 percent of women and most commonly occurs in women who are of normal body weight. Onset is usually during adolescence and is characterized by bingeing and purging, either by vomiting or using laxatives. Women with the disease often have a distorted image of their bodies, changes in brain chemistry and psychiatric symptoms such as depression, anxiety, obsessive-compulsive disorder and alcohol or other substance abuse. Though researchers know the symptoms and effects of bulimia, the exact causes of the disorder have yet to be uncovered.

Because malnutrition associated with eating disorders affects brain chemistry, Dr. Kaye and his colleagues compared 31 healthy volunteer women to 30 women who had recovered from bulimia nervosa--they were of normal body weight, had regular menstrual cycles and had not binged or purged for more than a year. The researchers assessed the recovered bulimia nervosa participants for persistent behavior disturbances and measured cerebrospinal fluid levels of the major metabolites of the neurotransmitters serotonin, dopamine and norepinephrine. They also gave the participants a non-therapeutic drug, m-chlorophenylpiperazine (m-CPP), that specifically affects the serotonin system and elicits hormonal and behavioral responses.

Dr. Kaye's team found that, compared to the healthy volunteers, the recovered women had increased levels of the serotonin metabolite and more negative moods and obsessions with perfectionism and exactness. The levels of the other brain chemicals, dopamine and norepinephrine, were normal in comparison. In addition, the group of recovered bulimia nervosa women had more anxiety and disorganized behavioral responses to m-CPP.

"While further research in this area is needed, we are beginning to gain an understanding of some of the causes of bulimia nervosa. Our hope is that this knowledge will contribute to more effective treatments and preventive measures for this disorder," said Dr. Kaye.