Eating Disorders Linked to Immune System
Bulimia, Anorexia May be Caused by Immune Disorder
Dec. 11, 2002 -- Some women who struggle with eating disorders like bulimia and anorexia nervosa may have immune systems that have been thrown out of whack and are now interfering with their bodies' own ability to control food intake and body weight.
A new study suggests that eating disorders may stem from some of type of immune system abnormality that causes other difficult-to-treat diseases like rheumatoid arthritis, multiple sclerosis, and lupus.
Anorexia and bulimia affect up to 3% of women at some point during their lifetime. Both conditions tend to develop at a young age and can cause serious mental and physical problems.
Anorexics tend to develop a distorted body image that causes them to limit food intake severely and become dangerously underweight, while bulimics go through cycles of "binging and purging" -- eating excessive amounts of food followed by induced vomiting.
Although the exact causes of the eating disorders are unknown, recent research has suggested that an abnormality in the nerves of the area of the brain that controls hunger may be to blame. And the researchers of the current study thought the problem might be that antibodies in the body cause damage to these nerves.
In the current study, Swedish investigators found that 74% of women with anorexia or bulimia had developed these antibodies that may make it harder for them to regulate food intake and body weight.
Their findings appear in the early edition of the December issue of the Proceedings of the National Academy of Sciences.
This may mean that the cause behind eating disorders may lie within the immune system. In conditions where the immune system goes awry, the body -- for an unknown reason -- forms antibodies that attack other areas of the body, as if they are foreign objects. This group of conditions is called autoimmune disorders and includes rheumatoid arthritis, lupus, and multiple sclerosis.
Researcher Serguei Fetissov of the Karolinska Institutet in Uppsala, Sweden, and colleagues say it's unclear whether the antibodies directly affect the brains of women with eating disorders. But laboratory tests in rats showed the antibodies could indirectly interfere with brain signals involved in metabolism and weight control.
However, a small number of healthy women also carried similar antibodies, and researchers say merely having these antibodies in the blood may not guarantee development of an eating disorder.
SOURCE: Proceedings of the National Academy of Sciences, early edition December 2002. -->