Thursday, 12 September 2013

Signs of autism in eating disorders?

To mention 'food and autism' in the same sentence can conjure up images of quite a few associations made in the peer-reviewed research literature over the years. You have for example, the growing body of work talking about how certain dietary interventions might be useful for some people on the autism spectrum (see here) and all the accompanying science on potentially why which seems to follow (see here).
Your differential analyser or mine? @ Wikipedia 

In another vein, issues with food and feeding behaviours, present in quite a few cases of autism, represent a far more practical issue to contend with; something which I've talked about before on this blog (see here).

Outside of the various sensitivities to things like taste, texture and smell which can affect a person's relationship with food (see here for a great overview* with autism in mind), questions are being asked about whether there may be more pathological issues to contend with as a result (see here**). I refer readers to the question asked by Prof. Gillberg 30 years ago on whether autism and familial anorexia might be linked (see here).

With this in mind, and slightly reversing the nature of any relationship, I want to discuss the paper by Baron-Cohen and colleagues*** (open-access) which suggested that females diagnosed with anorexia nervosa (AN) might being more likely to present with a cognitive style reminiscent of that seen in autism. Quite a nice overview of the study and its findings can be found here and due credit should be given to the article by Clare Allely which recently appeared in The Psychologist.

In essence (no, not that ESSENCE) we are talking about a group of adolescent females diagnosed with AN (n=66) compared with a control group of similarly aged young women without AN (n=1609). Based on the previous work looking at empathising and systemising (see here) styles in autism, participants completed questionnaires (EQ --- SQ-R --- AQ) to report on these attributes.

The results: "As predicted, the patients with anorexia has a higher AQ and SQ". In other words, the distribution of AN cases scoring higher on the AQ (see here for some more chatter about this instrument) was greater than that seen in the non-AN controls (see Figure 1 of the paper here). Ergo, more autistic traits in the AN group as per earlier research****. That also the AN group seemed to be better systemisers was another finding.

Whilst I have had my doubts about some of the earlier manifestations of the whole empathising-systemising theory (think the sweeping generalisations of Theory of Mind and autism) I have to say I am really interested in these recent results. I note also that another review study looking at the presence of autism in eating disorder populations***** likewise suggests that this might be a relationship which requires much further investigation.

If I had to throw a few spanners into the works outside of the study limitations already talked about by the authors, it would have to be that we should be cautious of making too many over-generalisations from this work. The recent 'mixed' findings by Courty and colleagues****** need to be considered. Although I am not an expert on eating disorders, it's still possible that we might also consider some shared comorbidity outside of autism as potentially accounting for some of the results at least in a sub-group. So for example, are features such as anxiety or obsessionality potential links between AN and the autism spectrum disorders particularly when talking about being better systemisers? The paper by Morsanyi and colleagues******* might be relevant here: [the systemising quotient] "was correlated with statistics-related attitudes, self-efficacy, and anxiety". I tip my hat also to the findings reported by Coombs and colleagues********. I'd also like to see more data on whether the described relationship between eating disorders and autistic traits holds for other kinds of eating disorders such as bulimia too?

Without also wishing to cause any offence, I do wonder about these results potentially being extended following in the tracks of the Gillberg letter. Take for example the paper by Grove and colleagues********* who talked about the empathising-systemising results being extended to other family members where autism is present. Does this therefore imply that we should be thinking about eating disorders potentially being more prevalent in other family members where autism is present? Indeed should we consider the possibility that the presence of a maternal (or paternal) eating disorder could be [another] subsequent risk factor for offspring autism?

To close, an Elvis track for you... His Latest Flame. I'd also like to mark the passing of David Barker (see here for his obituary) and his insightful contribution to science discussed in an earlier post (see here) which in an odd sort of way might also be relevant to today's discussions.

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* Cermak SA. et al. Food selectivity and sensory sensitivity in children with autism spectrum disorders. J Am Diet Assoc. 2010 February; 110(2): 238–246.

** Råstam M. et al. Eating Problems and Overlap with ADHD and Autism Spectrum Disorders in a Nationwide Twin Study of 9- and 12-Year-Old Children. Scientific World Journal. 2013; 2013: 315429.

*** Baron-Cohen S. et al. Do girls with anorexia nervosa have elevated autistic traits? Mol Autism. 2013; 4: 24.

**** Hambrook D. et al. Empathy, systemizing, and autistic traits in anorexia nervosa: a pilot study. Br J Clin Psychol. 2008 Sep;47(Pt 3):335-9. doi: 10.1348/014466507X272475.

***** Huke V. et al. Autism spectrum disorders in eating disorder populations: a systematic review. Eur Eat Disord Rev. 2013 Sep;21(5):345-51.

****** Courty A. et al. Levels of autistic traits in anorexia nervosa: a comparative psychometric study. BMC Psychiatry. 2013 Sep 10;13(1):222.

******* Morsanyi K. et al. Are systemizing and autistic traits related to talent and interest in mathematics and engineering? Testing some of the central claims of the empathizing-systemizing theory. Br J Psychol. 2012 Nov;103(4):472-96.

******** Coombs E. et al. An investigation into the relationship between eating disorder psychopathology and autistic symptomatology in a non-clinical sample. Br J Clin Psychol. 2011 Sep;50(3):326-38.

********* Grove R. et al. Empathizing, systemizing, and autistic traits: latent structure in individuals with autism, their parents, and general population controls. J Abnorm Psychol. 2013 May;122(2):600-9.

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ResearchBlogging.org Baron-Cohen S, Jaffa T, Davies S, Auyeung B, Allison C, & Wheelwright S (2013). Do girls with anorexia nervosa have elevated autistic traits? Molecular autism, 4 (1) PMID: 23915495