Researchers in Sweden have preliminary evidence that the brains of people suffering from anorexia and/or bulimia might be under attack from autoantibodies.
This would put the disorders in the category of autoimmune diseases, such as rheumatoid arthritis and multiple sclerosis, which occur when the body's immune system turns on itself and starts to destroy different parts of the body.
The finding, if true, would also radically alter the perception and treatment of these two prevalent eating disorders, which have traditionally been described in behavioral and developmental terms.
"We've seen hints of these abnormalities for a couple of years but this is a very, very strong paper that demonstrates quite convincingly that there's more to eating disorders than meets the eye," says Dr. Henry Anhalt.
"What is becoming clear is that energy metabolism is much more involved," adds Anhalt, director of the division of pediatric endocrinology at Infants and Children's Hospital of Brooklyn at Maimonides Medical Center in New York City
The results of the new study are detailed in this week's edition of the Proceedings of the National Academy of Sciences.
Bulimia and anorexia usually manifest themselves as obsessions with weight and body appearance. People with anorexia try to starve themselves to lose weight, often when no weight loss is needed. Those suffering from bulimia have uncontrolled eating binges followed by purging or vomiting. Often, individuals suffer from both disorders at the same time.
No one knows what causes anorexia and bulimia, but there is at least some suggestion of involvement from neuropeptides, which are chemicals that regulate metabolism and are secreted by the hypothalamus and the pituitary gland.
The Swedish researchers hypothesized that the hypothalamic system in the brain, which is responsible for the regulation of food intake, might be targeted by autoantibodies in women with anorexia and/or bulimia.
To test the theory, the investigators withdrew blood serum from 57 women between the ages of 17 and 42 who had anorexia, bulimia or both. Most of the women (74 percent) produced antibodies that, when applied to sections of rat brains and rat pituitary glands, selectively attached to cells that produce three specific neuropeptides: alpha-MSH, ACTH and LHRH.
Although that's all the researchers know right now, it is possible that the antibodies are destroying or interfering with the brain signals that regulate food intake and body weight.
"This is a possible scenario which we suggested, but it should be ultimately proven," says Dr. Serguei O. Fetissov, lead author of the study and a member of the department of neuroscience at Karolinska Institutet in Stockholm, Sweden.
The fact that a small number of healthy control subjects carried similar antibodies may help unravel the mystery further.
"It may be that the presence of autoantibodies... is related to activation of the stress axis," Fetissov says. "The presence of these autoantibodies could be a stress-related risk factor for the development of anorexia/bulimia, but other factors may trigger this disorder, including those which make women more vulnerable for anorexia."
More research is needed before these and other questions are answered.
"We are going to screen a larger group of patients with stress-related disorders for the presence of autoantibodies against neuropeptides of the stress axis," Fetissov says of his lab's next project. "We are also planning to work with experimental models of disorders potentially linked to autoantibodies against neuropeptides."
Even if the results are verified, it's likely that they would apply to a subset of people with anorexia and bulimia. But they may also apply to people who struggle with obesity. Obesity, of course, is one of the most pressing public health concerns facing Americans, Anhalt says.
"The study really expands our horizons and gives us food for thought," Anhalt says. Right now, physicians feel like "carpenters in a microchip factory," he adds.
Studies such as the Swedish one open the way for new, more finely tuned therapeutics that could target more specifically and more effectively the mechanisms that are responsible for other disorders, such as leukemia, Anhalt says.
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