Jan. 30, 2003 -- Current methods of classifying and treating patients with eating disorders are inadequate and the conditions are still poorly understood, says one of the world's top experts on eating disorders.
According to researcher and psychiatrist Christopher G. Fairburn, as many as half of patients with eating disorders are considered to have atypical conditions that are similar to either anorexia or bulimia but do not quite meet the criteria for those conditions. The researcher notes that sufferers often migrate from one eating disorder to another.
"This ... movement, together with the fact that anorexia nervosa, bulimia nervosa, and the atypical eating disorders share the same distinctive psychopathology, suggest that common mechanisms are involved in their persistence," Fairburn and colleague Paul J. Harrison write in the upcoming issue of the journal The Lancet. "However, the fact that eating disorders do not evolve into other conditions, lends support to the distinctiveness of the diagnostic category as a whole."
Fairburn, a professor of psychiatry at England's Oxford University, has written several books on eating disorders, including what is widely considered to be the definitive text on the subject. He and Harrison write that almost no research has been done on atypical eating disorders, even though recent studies suggest they are more common than either anorexia or bulimia.
All three conditions typically occur among adolescent girls and young women, and obsession with weight and shape is the most consistent characteristic. These women see themselves based on their weight and body image. Anorexics restrict food to the point that they stop menstruating and their health is jeopardized, but they tend to see this drastic weight loss as beneficial.
Bulimics usually have episodes of binge eating followed by purging. Their weight usually does not change because of the repeated binge/purge cycles. Many bulimics are distressed by their loss of control over eating, so they respond better to therapy.
Many atypical eating disorders, Fairburn and Harrison write, closely resemble the other two conditions. A patient's weight or body fat may be just above the threshold for anorexia or she may still be menstruating, for example. These women may not overemphasize body image but may feel stressed by their lack of control over eating.
Recent studies suggest that genetic predisposition plays a role in many eating disorders, with a few finding heredity to be even more important than environmental factors. One study shows that anorexia occurred in 55% of identical twins tested and only 5% of fraternal twins, while the corresponding figures for bulimia were 35% for identical twins and 30% for fraternal twins.
"After reviewing all of the evidence on genes, our conclusion was that it is not yet clear how important they are, and we certainly don't know at this point which particular genes are involved," Harrison tells WebMD. He adds that larger and more sophisticated studies are needed to answer the question.
With regard to treatment, Fairburn and Harrison found that much of the research has focused on bulimia, with less on anorexia and almost none on atypical eating disorders. They write that the most effective treatment for bulimia is a specific type of behavioral therapy that focuses on modifying the behavior and thinking associated with the disorder. Antidepressants have also been shown to be very effective for bulimia but are only modestly effective for treating anorexia.
The authors conclude that there is a pressing need for more treatment research that addresses the full range of eating disorders. National Eating Disorders Association (NEDA) president Craig Johnson, PhD, agrees.
"We particularly share (the concern of Fairburn and Harrison) for emphasizing research that explores the interaction of genetic and environmental processes, and the need for more research dollars to further the investigation of treatment," Johnson said in a statement to WebMD.