Saturday, 28 June 2014

On parental inflammatory bowel disease and offspring autism risk

The paper by Ane Birgitte Telén Andersen and colleagues [1] (open-access here) concluding "no evidence of an increased risk of ASD [autism spectrum disorders] among children born to parents with IBD [inflammatory bowel disease]" caught my eye recently.

Qays and Layla @ Wikipedia 
Based on an analysis of one of those Danish Registries which seem to be providing all-manner of important correlations and non-correlations, the authors looked for the presence of parental IBDs such as ulcerative colitis (UC) or Crohn's disease (CD) in the files of over a million children, including some who went on to receive a diagnosis of autism or ASD. They reported that: "The 10-year risks of ASD were 0.7% among children of parents with IBD and 0.9% among children of parents without IBD". Indeed, judging by other figures presented one might even assume that a parental diagnosis of IBD might actually be somewhat protective against offspring autism...

This is interesting data. I've talked before about the strength of these types of large datasets; big data in action you might say. This authorship team are also no strangers to looking at the offspring risks or not following a parental diagnosis of an IBD. Take for example their results on paediatric asthma [2] (open-access here) similarly concluding no evidence for "an increased risk of asthma in offspring with a parental history of IBD".

Certainly the numbers being talked about by Andersen et al mean their results have to be taken seriously and as the authors note "reassuringly suggest that neither maternal or paternal IBD increases the overall risk of ASD in a child". That being said, I was also intrigued by how the Andersen findings contrasted with other studies in this area. Take for example the results of the much smaller study by Mouridesen and colleagues [3] covered in a previous post (see here) which hinted at some increased frequency of autoimmune related conditions in parents of children with autism. Maternal UC was noted as a potentially important variable in that study. Obviously there is quite a difference in the participant numbers between the two studies but still it's a contrast.

It is important to note that Andersen et al are only commenting on how parental IBD diagnosis seems not to be related to offspring autism risk. They are not saying that the known IBDs or even some prodromal / new-variant IBD (see here) are not related to at least some cases of autism. I'm also minded to suggest that the Andersen results might even offer some support to the idea that IBDs, when established in cases of autism, might have more of an 'acquired' element to them over and above a genetic link. I say this if one (a) assumes that some cases of autism have an autoimmune element to them, and (b) that certain factors listed in relation to autism such as early antibiotic use [4] might also might have some bearing on the 'acquisition' of the IBDs (see here).

Music to close... Before Candy Crush there was Orange Crush by REM.

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[1] Andersen AB. et al. Autism spectrum disorders in children of parents with inflammatory bowel disease - a nationwide cohort study in Denmark. Clin Exp Gastroenterol. 2014 May 7;7:105-10.

[2] Andersen AB. et al. Parental inflammatory bowel disease and risk of asthma in offspring: a nationwide cohort study in Denmark. Clin Transl Gastroenterol. 2013 Aug 22;4:e41.

[3] Mouridsen SE. et al. Autoimmune diseases in parents of children with infantile autism: a case-control study. Dev Med Child Neurol. 2007 Jun;49(6):429-32.

[4] Niehus R. & Lord C. Early medical history of children with autism spectrum disorders. J Dev Behav Pediatr. 2006 Apr;27(2 Suppl):S120-7.

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ResearchBlogging.org Andersen AB, Ehrenstein V, Erichsen R, Frøslev T, & Sørensen HT (2014). Autism spectrum disorders in children of parents with inflammatory bowel disease - a nationwide cohort study in Denmark. Clinical and experimental gastroenterology, 7, 105-10 PMID: 24855384