Sunday, 25 May 2014

Leaky gut as a later life event in autism?

Leaky gut and autism. Yes, it happens and I've talked about it quite a bit on this blog. If you're bored of me mentioning this potentially important process and how it may tie into at least some parts of the very heterogeneous autisms, feel free to click away now.
Salisbury Cathedral @ Wikipedia 

If not, today's post centres on a short paper by Alexander Penn and colleagues [1] which looked at measured levels of intestinal permeability in infants deemed at high-risk of autism by virtue of having a sibling diagnosed with an autism spectrum condition compared to those in a low-risk category with no family history of autism. They concluded: "intestinal permeability continues to decrease even after 3 months as part of typical development and that hyperpermeability is a later event in ASD [autism spectrum disorder] and may not appear in the first year of life". I should mention that the testing tool of choice for gut permeability in this study was the lactulose/mannitol sugar absorption ratio which involves drinking a solution of the two sugars and measuring the urinary output some hours later to ascertain intestinal permeability.

The first part of the findings from Penn et al stressing that gut permeability might be a dynamic process is something really quite interesting. It's pretty well known that gut permeability in our earliest days of life is something rather different from what we [generally] experience as we mature bearing in mind that lots of different factors can seemingly affect intestinal permeability [2]. I don't really want to go into the hows and whys of this process but other authors have talked about it [3].

The related issue to note about the Penn findings is the role that different infant feeding strategies might have on intestinal permeability. Again, other authors have talked about this issue [4] so no need for some long discussions from me about this issue.

Then to that interesting sentence about "hyperpermeability is a later event in ASD". At least one of the high-risk kids examined in the study "demonstrated [intestinal] hyperpermeability" which begs the question: what happened to this infant compared to those who did not show similar findings? Did this finding correlate with subsequent development (or not) of autism and would this perhaps then have some role to play in those grand discussions about early red flags for autism? The other implication from leaky gut potentially not appearing "in the first year of life" is that this may be an example of something potentially acquired at least for some on the autism spectrum. My mind wanders back to all the discussions about regression and autism (see here) and whether this might be a physiological correlate to watch for in some cases. As to any precipitating factors 'causing' such regression, well, the obvious ones would be along the lines of food and what we already think we know about something like gluten and intestinal permeability. Whether there may be other factors or insults which might also be important to any relationship (e.g. gut bacteria) is something that really needs a lot more investigation.

To close, I'm not ashamed to admit that I actually quite enjoyed seeing New Kids on the Block on Friday evening with my better half. As one of a handful of very supportive husbands / boyfriends / significant others all stood with arms folded throughout the gig whilst the girls really had some fun, all I will say is my toes were tapping when it came to a few songs... The Right Stuff. And keeping the music thing going... this week One Direction are also visiting the North East and then there was the Radio 1 Big Weekend 2014 from Glasgow (Coldplay were excellent).

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[1] Penn A. et al. Intestinal permeability as measured by lactulose mannitol ratio continues to decrease during infancy after 3 months of age for both control infants and infants at high risk for autism spectrum disorders (LB751). The FASEB Journal. 2014. 28: LB751.

[2] Lambert GP. et al. Effect of aspirin dose on gastrointestinal permeability. Int J Sports Med. 2012 Jun;33(6):421-5.

[3] Weaver LT. et al. Intestinal permeability in the newborn. Archive Dis Child. 1984; 59: 236-241.

[4] Catassi C. et al. Intestinal permeability changes during the first month: effect of natural versus artificial feeding. J Pediatr Gastroenterol Nutr. 1995 Nov;21(4):383-6

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ResearchBlogging.org Alexander Penn, Tiffany Lai, Leslie Carver, Sharon Taylor, Geert Schmid-Schnbein, & Karen Dobkins (2014). Intestinal permeability as measured by lactulose mannitol ratio continues to decrease during infancy after 3 months of age for both control infants and infants at high risk for autism spectrum disorders The FASEB Journal, 28