December 2, 2005

Purging Disorder is a Distinct Eating Disorder

By Anne Harding

NEW YORK (Reuters Health) - Purging disorder appears to be a disorder that is separate from bulimia nervosa, Iowa researchers report in the International Journal of Eating Disorders.

Patients with purging disorder purge frequently, but do not binge eat, Dr. Pamela K. Keel of the University of Iowa noted in an interview with Reuters Health. Standard question series designed to screen for anorexia nervosa or bulimia nervosa may miss these patients, she adds, because they are of normal weight and they do not report binge-eating episodes.

As defined by the Diagnostic and Statistical Manual IV, bulimia nervosa is characterized by binge eating, while purging disorder falls into the category of "eating disorder not otherwise specified." However, Dr. Keel points out, recent research suggests that purging disorder may actually be more common than anorexia nervosa and bulimia nervosa combined.

Given that purging itself has serious medical consequences, she added, it is important to identify these patients.

To evaluate whether purging disorder might be a distinct entity from bulimia nervosa, Keel and her colleagues assessed 37 women with purging disorder, 39 women with bulimia nervosa, and 35 women without an eating disorder. Twenty-three of the women with purging disorder and 25 of those with bulimia nervosa completed follow-up assessments six months later.

While women with purging disorder showed a similar degree of eating disorder severity, body image disturbance and dietary restraint as the women with bulimia nervosa, they showed less impulsivity about eating, less impulsivity overall, less hunger, and less eating disinhibition, the researchers found. There was no difference in remission rates between women with the two conditions at six months follow-up.

Past studies have suggested binging in bulimia nervosa patients may be related to a dysfunctional satiety response due to impairment in the neurotransmitter serotonin and the gastrointestinal peptide hormone cholecystokinin, Keel and her team note.

"Results from the current investigation suggest that these systems may be prime candidates for understanding stable differences between purging disorder and bulimia nervosa," they write.

In the meantime, more study is needed to better characterize purging disorder and determine how best to treat patients with the condition, Keel said. "It would be a disservice to them to assume that treatments that work for bulimia nervosa would work for them."

SOURCE: International Journal of Eating Disorders, November 2005.