That means it could be contagious.
Anorexia nervosa has one of the highest mortality rates among all mental disorders, but there’s still a lot to learn about what actually causes the eating disorder.
A common explanation is that anorexia is triggered by psychological factors, but a team of leading medical researchers in the United Kingdom think there could be an intriguing biological explanation — they argue the disorder is caused by a bacterial infection.
"Psychological factors might be important, but are unconvincing as the primary or major cause,” the researchers said in a press statement.
Their argument is pretty compelling. Basically, a bacterial species (which they haven’t yet pinned down) infects a patient’s body, and then his or her immune system creates antibodies to fight off the infection. However, those antibodies become confused and begin to attack the patient’s own nerve cells instead, the researchers argue.
Interestingly, the scientists think that the symptoms of chronic fatigue and irritable bowel syndrome could also be explained by this autoimmune attack. It would explain the imbalance of rates between males and females acquiring these conditions, since it’s already known that women are at an increased risk of developing autoimmune conditions, as the American Autoimmune Related Diseases Association reports.
“The female excess in Irritable Bowel Syndrome, Chronic Fatigue Syndrome and Anorexia Nervosa is equally extreme,” the researchers said, “and therefore this fits with the idea that auto-antibodies to nerve cells could be part of the pathogenesis of these conditions."
Additionally, the scientists say the bacteria hypothesis could explain some of the hallmark symptoms of anorexia that most people associate with the influence of models and unrealistic body images.
The limbic system in the brain is tied to emotional processing, and antibodies acting on the system could induce extremes of emotion, like disgust and fear — key players in anorexia.
"These then become linked, in the minds of adolescent girls, to culturally determined ideas of what is, and what is not, the ideal body shape and size,” the researchers explain. “It is then a small step for disgust and fear to be directed to food and obesity which the fashion industry currently demonises."
If the scientists’ bacteria hypothesis is confirmed by further research, that will mean that anorexia could actually be contagious.
However, even if the condition does have a bacterial origin, the scientists clarify that social factors are still likely to influence who develops the eating disorder and who doesn’t.
Next, the team plans to test the hypothesis on animal models in a lab, and will work at identifying the bacteria responsible for causing the immune system to attack the body’s own nerves.
"If we can isolate the culprits perhaps we can restore the correct bacterial balance," one of the co-authors, Quenton Wessels, told The Telegraph. "We hope to move into the lab over the summer, and hopefully have an answer by the end of the year."
If the scientists go on to find supporting evidence for their hypothesis, the next step will be figuring out how to eliminate the bacteria that are triggering the reaction, and they say healthy blood transfusions could be a potential way to do so.
The paper is published in the journal Medical Hypotheses.