Restrictive eating disorders: aetiological, epidemiological and neurodevelopmental aspects

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You are originally from Germany, what made you choose to do your doctoral studies in Sweden?

Well, this was actually somewhat of a coincidence. During my Bachelor studies in Germany, I started to learn Swedish out of curiosity. This led to an exchange semester in Sweden during my Master’s, where I got in contact with the Gillberg Neuropsychiatry Centre (GNC) and became very interested in their research. I became a Master’s thesis student at the GNC, then a research assistant, and finally a PhD student!

 The most unexpected finding was certainly that we were not able to detect elevated autistic traits in children who later went on to develop anorexia nervosa, when we looked at this in several thousand twins in Sweden.

Lisa, you are almost ready for your dissertation. Can you please tell me what your thesis is about?

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My thesis is about two restrictive eating disorders: anorexia nervosa and Avoidant/Restrictive Food Intake Disorder (ARFID). Both are characterised by severely restricted food intake, which commonly leads to substantial weight loss and significantly low weight, and the need for nutritional supplementation. My thesis looked at a range of different aspects of these disorders, for example, we studied the intricate link between anorexia nervosa and autism spectrum disorder, the comorbidity of ARFID with autism and other neurodevelopmental disorders, and the prevalence of ARFID in children, which is still largely unknown. Furthermore, my thesis examined whether diagnosed eating disorders can be conceptualised as the extreme manifestation of disordered eating behaviours that are continuously distributed in the population when it comes to the underlying genetic risk factors.

In summary, my thesis confirmed how difficult it is to disentangle the relationship between anorexia nervosa and autism. For example, we found that difficulties in recognising other people's emotions, which are believed to be characteristic of anorexia nervosa, might in fact not be a trait inherent in anorexia nervosa, but instead be limited to the subgroup who also has autism. We also conclude that more prospective studies are needed (i.e., assessing autistic traits before the onset of anorexia nervosa) and that the way of measuring autistic traits in (young) girls needs to be improved, in order to not miss girls with autism. My thesis furthermore showed that ARFID likely has a point prevalence of 1% in young children and that it is associated with increased risk for a range of neurodevelopmental problems and disorders, as opposed to anorexia nervosa, which is more exclusively associated with autism, but less with other neurodevelopmental disorders. Finally, my thesis showed that anorexia nervosa is genetically more demarcated from milder disordered eating behaviours  than other adolescent-onset eating disorders such as bulimia nervosa are. That means, while most psychiatric disorders can be defined dimensionally (i.e., as the extreme manifestation of their associated symptoms and traits that are continuously distributed in the population), this might not be the case for anorexia nervosa. The thesis including a more extensive summary can be found here Restrictive eating disorders: aetiological, epidemiological and neurodevelopmental aspects

 However, one of the more difficult periods was the first year after I started my PhD, when I was trying to figure out how the research world and being a PhD student at GU works, and also how to find a good work-life-balance.

What has been one of the most unexpected findings?

The most unexpected finding was certainly that we were not able to detect elevated autistic traits in children who later went on to develop anorexia nervosa, when we looked at this in several thousand twins in Sweden. We know that there is an increased prevalence of autism in individuals with anorexia nervosa, so we would have expected to see more autistic traits in children with later anorexia nervosa. There are several possible explanations for this result, but it remains fascinating. If you want to read more about this study you can find it here: Anorexia nervosa and autism: a prospective twin cohort study.

What has been the hardest part of your PhD studies?

I would say that there was not one hardest part, it was more up and down over the years. However, one of the more difficult periods was the first year after I started my PhD, when I was trying to figure out how the research world and being a PhD student at GU works, and also how to find a good work-life-balance. Having four years in front of you to complete your PhD, it is extremely difficult to estimate how much you need to get done in how much time, so it can be hard to know when you have worked enough. Also, it can take a while (i.e., years) until your first article is published, so one needs to be able to stay confident and tolerate this (very) delayed gratification. I also thought it was challenging to deal with the massive amounts of literature that are out there, and to find ways to synthesise it and to write more efficiently.

What have you enjoyed the most about your PhD studies?

I enjoyed so many things about my PhD studies. Most of all, to have the opportunity to educate myself constantly, to gain new knowledge and skills almost on a daily basis—and to get paid for it. Quite amazing if you think about it. The research task I enjoy most is data analysis, and teaching myself more about statistics, but surprisingly, I also enjoyed thesis writing more than I had anticipated (I was NOT looking forward to it). I am also very grateful that I had the possibility to travel a lot during my PhD (to courses and conferences). Considering the current situation with COVID-19, it is possible that we see significant changes for research meetings in the future, as physical meetings might continue to be replaced by virtual ones.

Can you name some of the most pressing research questions within your field at the moment?

One of the most important research questions at the moment is whether and how closely ARFID and anorexia nervosa are related, for example, can early-onset ARFID potentially develop into anorexia nervosa and how high is this risk. The motivations for food avoidance are very different in anorexia nervosa and ARFID, and it is not entirely clear, why these motivations would change at some point during development. So far, there are no prospective studies that have investigated this. It is also important to find out how autism fits into the picture, as it is more common in both anorexia nervosa and ARFID, compared to people without these eating disorders.

What would you like to do after your PhD studies are finished?

I am passionate for psychiatric research and want to continue on the research path as far as it takes me, so to speak. I will continue to work at the GNC for about half a year after my defense and try to get funding for a post-doc project in the field of eating disorders, researching questions closely related to the topics I studied in my PhD.