Anorexia Nervosa is a notoriously difficult condition both to characterise and treat. It is generally known as an eating disorder but has strong links to anxiety disorders such as Obsessive Compulsive Disorder, attachment disorders, depression and even other eating disorders.

There are a surprisingly small number of studies which have investigated how best to treat anorexia, and one meta-analysis by Hartmann et al (2011) failed to find evidence for the effectiveness of any psychological treatment.

Traditional pharmacological treatments are equally ineffective.The drug therapies administered are aimed at treating symptoms such as weight loss and depressive thoughts rather than the underlying cause of the condition. In many ways this can be considered an appropriate therapeutic method; excessive weight loss can be fatal, depressive thoughts can lead to self-harm and diminish the effectiveness of psychological therapies and so on.

Nevertheless, drug treatments cannot cure the disorder.

A new theory by scientists at Lancaster University, however, may help to finally develop an effective treatment for the condition. They propose that anorexia may have a very physical root cause – bacterial infection.

“We think specific bacteria is setting it off. It is almost like the microbes within you can determine you mood, which is profound in itself.” – Dr Quentin Wessels, Lancaster University.

The proposed mechanism, which will be tested in animal models, suggests that a certain bacteria triggers the immune system to attack healthy areas of the body. This is not a novel idea; in fact, there are many conditions which manifest in similar ways – multiple sclerosis, lupus and rheumatoid arthritis. These are known as auto-immune disorders, and are not always particularly well understood.

Dr Wessels explains how a similar mechanism may be causing anorexia nervosa:

“The immune system responds to something that is foreign by producing an antibody which then attacks something else. Auto-antibodies acting on the brain’s limbic system could induce extremes of emotion including disgust and fear. 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. It is then a small step for disgust and fear to be directed to food and obesity which the fashion industry currently demonizes.”

Of course, anorexia does not only affect adolescent girls – far from it. Despite Dr Wessel’s slight faux pas, the theory is based on good scientific research.

For instance, an animal study by Huerta et al (2006) found that antibodies acting on the limbic system could cause alterations in fear behaviour. What’s more, there is already a strong body of research to suggest that women are at greater risk than men of developing auto-immune disorders (e.g. Fairweather et al, 2008); 90% of those suffering with anorexia are female. If anorexia were an auto-immune disorder, the statistics would fit.

Despite this theory drawing heavily from biology and neuroscience, the team are not saying that anorexia is not a psychological disorder – rather they suggest there is an interaction between mental health and biology which causes the symptoms of anorexia to develop.

Along with Dr Wessels, Dr Jim Morris from the University Hospitals of Morecambe Bay NHS Trust and Dr Sue Broughton from Lancaster University explain more:

“Psychological factors might be important, but are unconvincing as the primary or major cause. There might, for instance, be an increased incidence of physical and sexual abuse in childhood in those who go on to manifest functional disorders. It is easy to see how this could influence symptoms in adults but it stretches credulity to imagine abuse as the sole and sufficient cause of the functional disorder.”

Although this idea may seem radical to some, it may be exactly what is required to treat anorexia. It is a notoriously difficult and complex disorder which affects a wide range of people. It is also very misunderstood. Applying a more ‘traditional’ medical theory to its etymology may help to encourage a greater belief and understanding in the condition, which, in turn, will promote more research to discover treatments.

A significant amount of research will need to be conducted in order to set about proving Dr Wessel’s theory. If correct, however, it could eventually lead to a treatment which doesn’t simply target the symptoms of anorexia, but aims directly at the root cause of the condition. Combined with effective psychological therapy, such a treatment could spell the end of a condition which causes premature death in 20% of sufferers (B-EAT).

To find out more about the hypothesis provided by Morris, Broughton and Wessels, take a look at their article published in Medical Hypotheses.