The following studies detail associations observed between various features of autism spectrum disorder (ASD) presentation and peculiarities in gut and gastrointestinal (GI) functions. “Correlation is not the same as causation” is an oft-heard phrase and importantly, suggests caution when making causal assumptions.The accumulation of such consistent associations, however, give us reason to focus our research efforts. We at N of One believe that the associations have now accumulated in a sufficient and consistent manner to merit a sustained research effort around GI functions, the gut microbiome and ASD, with the promise of new insights into the label.
Gut problems linked to anxiety in autism?
Anxiety among young boys with autism might be at least partially explained by the presence of particular gastrointestinal (gut) issues according to new research from Hong Kong. Looking at nearly 140 boys aged 4-11 years, half of whom were diagnosed with autism, researchers observed some potentially important associations between the presence of measured anxiety and several functional gut disorders characterised by nausea, vomiting and pain. Importantly, the link between anxiety and gut issues was not observed in control participants who were not autistic. This work follows other studies that have arrived at similar conclusions stressing the importance of the gut-brain interface in autism and how physical health issues may well have important effects on psychological wellbeing in autism.
Wong OWH, Lam AMW, Lai KYC, Ma SL, Hung SF, Chan S, Wong S, Leung PWL. An elevated anxiety level among prepubertal autistic boys with non-treatment- seeking functional gastrointestinal disorders: A case control study. Autism Res. 2021 Jun 11. doi: 10.1002/aur.2555.
Parental inflammatory bowel disease (IBD) and offspring autism: a link
Drawing on information gathered from four different study designs including a technique called Mendelian randomization that provides causal information, researchers from the UK and Sweden reported an association between parental inflammatory bowel disease (IBD) and offspring autism. Currently a preprint paper including participant numbers in the tens of thousands, the study triangulated various evidence suggesting that maternal IBD such as ulcerative colitis significantly increased the risk of offspring autism. Authors concluded that “perinatal immune system dysregulation, micronutrient malabsorption and anaemia” may be implicated in their findings.
Aws Sadik, Christina Dardani, Panagiota Pagoni, Alexandra Havdahl, Evie Stergiakouli, Jakob Grove, Golam M. Khandaker, Sarah A. Sullivan, Stan Zammit, Hannah J. Jones, George Davey Smith, Christina Dalman, Håkan Karlsson, Renee M. Gardner, Dheeraj Rai. Parental inflammatory bowel disease and autism in the offspring: Triangulating the evidence using four complementary study designs. medRxiv 2021.06.09.21258393;
‘Leaky gut’ and behavioural severity in autism
The presence of a marker of intestinal permeability (the so-called ‘leaky gut’) correlated with behavioural severity scores for autism according to new research from Canada. Included as part of a suite of compounds that are associated with inflammation, levels of intestinal fatty acid binding protein (I-FABP) were found to be associated with “more severe behavioural phenotypes” in young children with autism in this cohort. Such findings follow many years of research and clinical interest into a possible role for intestinal permeability in autism. Again focusing on a gut-brain axis, leaky gut has been linked to immune, digestive and food-related issues in autism.
Teskey G, Anagnostou E, Mankad D, Smile S, Roberts W, Brian J, Bowdish DME, Foster JA. Intestinal permeability correlates with behavioural severity in very young children with ASD: A preliminary study.
J Neuroimmunol. 2021 May 12;357:577607.
Abstract: https://pubmed.ncbi.nlm.nih.gov/34044209
The gut microbiome is different in autism (again)
There are significant differences in the composition of the bacteria residing in the gut in boys diagnosed with autism compared with asymptomatic children according to new research from China. Analysing stool samples from over 50 boys with ASD, researchers observed some important differences compared with control samples; many of which had already been previously described in the research literature. Key bacterial species identified showed connection with GI immune function and barrier functions. Further analysis of their findings also led researchers to conclude that there may be diagnostic potential in the observed differences, meaning gut bacterial profiles could one day help with early, objective identification of autism.
Ye F, Gao X, Wang Z, Cao S, Liang G, He D, Lv Z, Wang L, Xu P, Zhang Q. Comparison of gut microbiota in autism spectrum disorders and neurotypical boys in China: A case-control study. Synth Syst Biotechnol. 2021 May 21;6(2):120-126. doi: 10.1016/j.synbio.2021.03.003.
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