Brain reaction may up anorexia

Immune attack could cripple appetite control.
10 December 2002

HELEN PEARSON

Around 1 in 200 anorexics die each year. © GettyImages

Some eating disorders could involve the body's immune system rounding on the brain, Swedish researchers are proposing.

Three-quarters of the anorexic and bulimic women studied by Serguei Fetissov of the Karolinska Institute in Stockholm carry blood antibodies targeted against appetite centres in the brain, he finds. Just 16% of those without eating disorders have such antibodies¹.

The antibodies may stop nerves responding to hormones that control hunger, Fetissov says, and so contribute to eating problems. If the idea proves to be correct, suppressing the aberrant molecules might treat the disease; diagnosis could also be improved on the basis of the presence of the antibodies.

Neuroscientist James McNamara of Duke University Medical Center in Durham, North Carolina, agrees that the hypothesis is plausible. "It's easy to imagine you could mount an attack on a specific population of neurons," he says.

McNamara and others have evidence that some cases of epilepsy and of the sleep disorder narcolepsy might also be attributed to wrongly aimed antibodies. "My suspicion is that a subset of many common nervous-system disorders could be auto-immune in nature," he says.

Slim pickings

Anorexia, the avoidance of food, and bulimia nervosa, or binge eating, affect around 3% of women and a smaller percentage of men. Around 1 in 200 anorexics die each year. Treatment involves psychotherapy, nutrition and sometimes medication such as anti-depressants.

The disorders were once though to be largely in the mind. Now, however, "we're recognizing more and more that there are powerful biological contributions to anorexia", says Walter Kaye, who works on eating disorders at the University of Pittsburgh in Pennsylvania.

For example, recent studies have suggested that some people carry a genetic susceptibility to anorexia. This could, for example, encourage the immune system to turn on its own tissues. Genetic predispositions are thought to contribute to other auto-immune diseases such as multiple sclerosis, type II diabetes and rheumatoid arthritis.

Alternatively, Fetissov speculates that prolonged or acute stress in anorexics might stimulate the immune attack. One of the misdirected antibodies detected by the team is aimed at adrenocorticotropic hormone, which is released in response to stress. This idea fits with evidence that children with anxious, perfectionist personalities are more at risk of developing anorexia.

But the team has yet to show whether the suspect antibodies actually cause the eating disorders, or are simply a symptom of them. Kaye remains circumspect: "It's an intriguing lead," he comments.

1. Fetissov, S. O. et al. Autoantibodies against -MSH, ACTH and LHRH in anorexia and bulimia nervosa patients. Proceedings of the National Academy of Sciences, published online, doi:10.1073/pnas.222658699 (2002). |Article|