Genetics study findings signpost new lines of investigation for anorexia treatment

Anorexia nervosa is a condition with serious emotional and physical consequences. Emotional consequences include deep distress, isolation, and loss of pleasure in things that once were loved. Physical consequences can be long-term and severe, and in the worst case anorexia can be fatal. There are some treatments that help, but not everyone, and the problem remains in need of innovative interventions for the people experiencing the disorder and their families.

A new study just published in Nature Genetics brings hope of some new ways of approaching the disorder. Researchers have found eight genetic variations which are associated with greater risk of anorexia.

The study used Genome Wide Association, looking at a large data set of people’s genetic material (obtained by blood test or saliva sample) and observing genetic differences in people with a diagnosis of anorexia compared to people without anorexia. Eight genetic variants were found to be associated with having anorexia.

The study used data from people from a wide range of ages, from teenagers to those in their 70s, and from a range of international locations, with collaborations from different parts of the world.

The study also explored genetic correlations with other illnesses and traits. The patterns they saw were associated with other mental illnesses such as OCD, which fits with clinical reports of people experiencing both diagnoses. Anorexia also showed genetic correlation with anxiety, which we know is often experienced by people with anorexia. Now we know that, in part, has a genetic cause. The genetic correlations which have caused more excitement are ones which we know are involved in metabolism.

Figure from Nature Genetics

This means that a predisposition for anorexia is likely to relate to a person’s natural metabolism. This opens up a new way of thinking about anorexia, encouraging us to think about both metabolic and psychological aspects of the illness. The study’s findings don’t diminish the importance of thinking styles and environmental influences, but they add an additional and rich perspective on possible physical risk factors and interventions that are waiting to be investigated.

Coverage of this study has often involved surprise that the body can be involved so much in what has been traditionally labelled as a psychiatric illness.

We really shouldn’t be surprised that both mental and physical are involved. We know that that mental phenomena are produced by physical changes in the brain and body. We know, too, that both genes and environment matter, and that there is an interaction between the two (epigenetics and gene x environment interaction). In some ways we could even argue that ‘mental’ and ‘physical’ are different ways of explaining the same thing.

The idea that mind and body are split and separate can be traced back to the philosopher Descartes (proponent of Cartesian dualism or the mind-body divide). This way of thinking is woven into a lot of our language about the mental and the physical, but it doesn’t do us any favours when we think about treating mental or physical illness, and in particular how to help people experiencing anorexia.

Cynthia Bulik, Professor at both the University of North Carolina Center of Excellence for Eating Disorders and the Karolinska Institute, is the lead author of the paper and has written a series of blogs on the project, including an explanation of how “neither genetics nor environment is destiny.”

Bulik explains anorexia as a complex trait, influenced by hundreds or thousands of genes as well as many environmental factors. Our risk is a combination of our genetic risk and buffering (protective) factors, and our environmental risk and buffering factors. Epigenetic factors: the ways that environment changes the expression of our genes, are also in the mix. The current research gives us more information about the genetic risk factors, adding another piece to the jigsaw of our understanding.

The findings of this study signpost new targets for research into early intervention improvements, and the research which will be carried out next is being shaped not only by the research findings but also by the feedback from people with experience of anorexia who took part in the study and who helped to recruit others.

One area for research to concentrate on is how and when is best to intervene. If we know who is high risk and why then we should be able to tailor treatments more intensively and more accurately.

Cynthia Bulik explained: “At this point, when someone comes to our office for the first time… it’s pretty much a one size fits all approach. If we could tell from the very beginning on the basis of genetic, family history, and other environmental information whether someone is at greater risk for developing a severe and chronic course, we could alter our approach.” More intensive and tailored treatment could be offered to those at higher risk.

Bulik continued: “Or, for example, if our genetic work begins to identify subtypes based on cause (e.g., more metabolic versus more psychiatric subtypes), we could theoretically tailor our interventions from the very beginning and not just intervene early, but also intervene in a personalized or tailored manner that targets causal factors of the illness for that particular person.”

This doesn’t mean that existing psychological treatments will be taken away, but they could be enhanced by this new knowledge, to include treatments which at least explain or possibly even change metabolism. The more we understand risk mechanisms, both physical and psychological, hopefully the better we will be able to help prevent relapse too.

For more on this study read Cynthia Bulik’s 4-part blog series here.

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