Reprinted from Eating Disorders Review
November/December 2005 Volume 16, Number 6
©2005 Gürze Books
Purging disorder (PD) is an eating disorder reported among normal-weight individuals who repeatedly purge without objective binge episodes. This disorder falls loosely into the category of an eating disorder not otherwise specified, or EDNOS, but has some characteristics of bulimia nervosa (BN).
Dr. Pamela Keel and her associates designed a study to examine the clinical significance and distinctiveness of purging disorder by comparing three groups of women, including women with DSM-IV bulimia nervosa (BN, purging subtype), women with PD who would have met DSM-IV criteria for BN purging subtype except for the absence of large binge episodes, and non-eating disordered controls (Int J Eat Disord, 2005:191). The study group included 111 women aged 18-45 years, who had a body mass index between 19 and 25 kg/m2, and who were recruited from the community.
The participants completed questionnaires and face-to-face structured clinical interviews at baseline. Follow-up assessments occurred approximately 6 months later and included the Eating Disorders Examination (EDE) interview and all baseline self-report questionnaires.
Compared with women in the control group, women with PD seemed significantly impaired on measures of eating pathology, general psychopathology, and impulsiveness/personality disorders. Women with PD did not differ significantly from women with BN on measures of eating disorder severity, body image disturbance, or dietary restraint.
The differences that did emerge between PD and BN may help explain the disparity in the amount of food consumed during self-reported binge eating episodes as well as the frequency of binge-purge episodes. Women with BN reported greater disinhibition around food and greater hunger compared with women with PD. Previous studies have suggested that binge eating episodes in BN are associated with a reduced satiety response mediated through blunted serotonin (Arch Gen Psychiatry 1997; 54:529) and cholecystokinin function (Am J Clin Nutr 1997; 65:114). These two systems may provide clues to better understanding differences between PD and BN.
PD: Not more severe than BN
When the authors compared mean depression and anxiety scores, the findings varied, suggesting that differences may change over time. For example, depression and anxiety were significantly lower in the PD group in the current study than in the PD group in a previous study by the authors.
PD clearly occurs among individuals with no history of BN, and there is no indication that PD represents a more severe eating disorder than, or a more ominous form of, BN. Although some might view PD as a less severe disorder compared with BN (due to differences in hunger, disinhibition, and binge/purge frequency), the authors note that it is merely a matter of a better understanding of the pathology associated with BN.
Individuals with PD are characterized by a tendency to become locked into negatively reinforced behaviors. Similar to compulsions in obsessive-compulsive disorder, purging in PD may be maintained by a strong need to reduce anxiety and the threat of unwanted outcomes, such as weight gain.