"the first nationwide population-based study to investigate the risk of CFS in patients with IBD"

The quote titling this post - "the first nationwide population-based study to investigate the risk of CFS [chronic fatigue syndrome] in patients with IBD [inflammatory bowel disease]" - comes from the research published by Shin-Yi Tsai and colleagues [1].

Inflammatory bowel disease (IBD) covers quite a bit of diagnostic ground, but typically refers to ulcerative colitis (UC) or Crohn's disease (CD). There are many similarities between the conditions, but also some important differences too (see here). Both conditions manifest in the bowel (inflammation) and have pathological effects; both also typically show functional bowel symptoms too.

Utilising that fabulous (but sadly now defunct) research resource that was the National Health Insurance Research Database (NHIRD) in Taiwan, researchers set out to "evaluate the subsequent risk of CFS in patients with IBD" on the basis of "possible common pathophysiology between IBD and CFS" among other things. One of those 'pathophysiological' mechanisms quite prominently featuring in the Tsai article is "a similarity to the impaired intestinal mucosa of IBD." Interesting (see here).

So, from a starting population of a million people (or medical insurance records of a million people), authors whittled the figures down to the thousands in two groups: an IBD group (n=2163) and a non-IBD group (n=8652). All were "newly diagnosed" with IBD apparently; and none had a previous diagnosis of CFS "before the index date." Then: "Both groups were followed from the index date until the diagnosis of CFS, withdrawal from the NHI program, or December 31, 2011" with said CFS diagnosis following the Fukuda/CDC criteria.

Results: before heading into the CFS frequency figures according to group, there was another important observation made, potentially pertinent to a gut-brain connection: "The prevalence of depression, anxiety, [and] sleep disorder... was higher in the IBD group than in the non-IBD group." Indeed, the increased frequency of sleep disorder in the IBD group *might* have some important 'connection' with another diagnosis where sleep and 'gut issues' has been mentioned (see here and see here). And I might as well also mention depression and anxiety in that context too (see here).

Continuing: "After adjustment for age, and comorbidities, the risk of CFS was higher in the IBD group than in the non-IBD group (adjusted HR, 2.25; confidence interval [CI], 1.70–2.99)." There was also a possible sex-linked relationship too: "we identified male sex, advanced age, absence of comorbidities, and CD as the predictors of increased CFS risk." There's a pretty little diagram to accompany the Tsai findings (see here) outlining what *could* be going on with regards to IBD and CFS. Terms like 'bacterial translocation' and 'immunoinflammatory pathways' are used, in line with some other research in this area [2]. There's no mention of any psychobabble 'biopsychosocial' or the like in the Tsai paper which is always a good thing.

What else is there to say? Well authors go on to mention about the possibility of "intrinsic defects in IBD patients that precipitates CFS" which could have some quite profound implications for at least some cases of CFS. They added that future work might want to have a look at what certain immunotherapies indicated for some IBDs * might* mean for CFS and it's potential *treatment* too. We'll have to wait and see.

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[1] Tsai S-Y. et al. Increased risk of chronic fatigue syndrome in patients with inflammatory bowel disease: a population-based retrospective cohort study. Journal of Translational Medicine. 2019; 17:55.

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Serum zonulin testing via ELISA: be very careful

I appreciate that the findings reported by Mary Ajamian and colleagues [1] probably aren't going to set many research hearts racing. Their observations that "current commercial zonulin assays are not detecting the actual protein as prehaptoglobin-2" is not exactly 'change the world' science, but that doesn't mean that they aren't important findings.

So, zonulin is the name of the research game. A protein described with properties "capable of reversible tight junction disassembly and, therefore, is implicated in the regulation of mucosal permeability" means that zonulin and dysregulation of the zonulin pathway has found a home in the science of 'gut permeability' a.k.a leaky gut. And it is with mention of the misnomer called 'leaky gut' and it's *association* with some autism (see here) that I gravitated towards the Ajamian findings. Indeed, zonulin has already made a mark in autism research too (see here). We'll come back to this shortly.

Researchers zoomed in on some of the commercially available methods currently available to 'test for zonulin' - "commercially-available ELISA assays" - and whether they are cutting the scientific mustard. And before I go on I should mention that Ajamian et al aren't the only ones who have looked at this issue [2]. Two ELISA assays were examined: "from CUSABIO (Wuhan, China) and Immundiagnostik AG (Bensheim, Germany)" and pitted against each other and various other analytical techniques to assess "whether the assays are reliably detecting zonulin as prehaptoglobin-2 and if not, what they may be detecting instead." I note the words 'mass spectrometric analysis' are also used in the Ajamian paper, which is music to my analytical ears.

Results: "Serum samples were collected from well-characterised patients and healthy individuals between the ages of 16 and 70 years living in Melbourne, Australia." Those 'well-characterised' participants included those diagnosed with non-coeliac wheat sensitivity (NCWS), coeliac disease, and ulcerative colitis (N=93) and their results were compared with nearly 50 asymptomatic controls. "The majority of study participants were zonulin-producers" as haptoglobin phenotype (see here) was also described in the Ajamian study.

Then to the serum [purported] zonulin levels as measured by those commercial assays: "Compared with the cohort of healthy individuals with a median (IQR) of 0.00 (0.00) ng/mL, patient median (IQR) values for purported zonulin were elevated (all p<0.0001) at levels of 0.032 (0.90) ng/mL in NCWS, 0.07 (1.27) ng/mL in coeliac disease, and 1.73 (2.17) ng/mL in ulcerative colitis" using the CUSABIO assay. Unfortunately, when compared with the other commercial assay (the Immundiagnostik assay), there was apparently little relationship observed between the two when it came to [purported] zonulin levels. And things didn't get any better when for example we are told that "2 of 19 participants who were zonulin non-producers had levels detected by CUSABIO assay."

Various other experiments were carried out and reported on in the Ajamian paper. These included attempts to find out what else might be being picked up by those ELISA assays. Unfortunately, even with the notable analytical prowess of something like mass spectrometry, no definitive compound(s) emerged. Something called complement C3 is discussed, as are other potential matches: "haptoglobin, and albumin." But again unfortunately: "neither complement C3 nor haptoglobin, despite both being candidate target proteins as determined by mass spectrometry, was detected by the CUSABIO assay." So we're not really any further forward when it comes to what might be being detected by such assays.

"In conclusion, the current commercial zonulin ELISA assays investigated in this study detect different proteins, neither of which was zonulin. Therefore, there can be no value of circulating concentrations in assessing intestinal mucosal barrier dysfunction and permeability until the target proteins are indeed identified." A harsh conclusion but faithful to the results observed. What this means is that the literature already published talking about zonulin levels in this, that and t'other label/diagnosis/condition (see here) need to be treated with some caution. And yes, that includes studies that have looked at zonulin levels in autism (see here) and related labels like attention-deficit hyperactivity disorder (ADHD) (see here).

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[1] Ajamian M. et al. Serum zonulin as a marker of intestinal mucosal barrier function: May not be what it seems. PLoS One. 2019;14(1):e0210728. Published 2019 Jan 14.

[2] Scheffler L. et al. Widely Used Commercial ELISA Does Not Detect Precursor of Haptoglobin2, but Recognizes Properdin as a Potential Second Member of the Zonulin Family. Front Endocrinol (Lausanne). 2018;9:22.

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'Mucosal healing' in treated coeliac disease "may come at a cost of an increased risk of mood disorders"

I was really quite intrigued by the findings reported by Jonas Ludvigsson and colleagues [1] attempting to "examine the relationship between anxiety, depression and mucosal healing in coeliac disease." Intrigued because such findings tap into a couple of potentially important areas such as the whole gut-brain 'being linked' bit (see here and see here) and how gut permeability (a.k.a leaky gut) might be something quite important to quite a few different labels/diagnoses/states (see here).

I should perhaps briefly go through a few choice terms before starting. Coeliac disease (sometimes written as celiac disease) is the archetypal 'food affects physiology' condition as per it's description encompassing the words 'gluten', 'autoimmune disease' and 'gastrointestinal'. Part of the biological profile of coeliac disease (CD) is involvement of the gut mucosal membrane and the characteristic 'flattening' of the mucosal surface reducing the capability to properly absorb various nutrients. This is known as villous atrophy and is measured using the Marsh criteria. Luckily, for most people with CD, when a gluten-free diet is installed to treat/manage CD, the gastrointestinal (GI) pathology linked to villous atrophy abate and mucosal healing can take place as long as gluten remains excluded from the diet.

Ludvigsson - a name not unfamiliar to all-research-things coeliac disease - and colleagues sought to look at the presentation of certain extra-gastrointestinal symptoms as a function of mucosal healing (through use of a gluten-free diet) or persistent villous atrophy. They analysed data collected over nearly 40 years "on all small intestinal biopsies with villous atrophy from Sweden's 28 pathology departments." They also garnered data on the presence of a diagnosis of depression and/or anxiety, and married the two data sets together...

Results: "During follow-up, 123 (2.8/1000 person-years) individuals with mucosal healing had developed anxiety, compared to 94 (2.1/1000 person-years) with persistent villous atrophy." What this means is that whilst the presentation of anxiety was spread both across those who did and did not seemingly biologically benefit from the use of a gluten-free diet, those who showed gut healing were seemingly at "a higher risk of future anxiety." A similar trend was also noted when it came to a diagnosis of depression. This led researchers to highlight how "the goal of mucosal healing may come at a cost of an increased risk of mood disorders."

I was truly in head-scratching mode when it came to these findings. I don't know if it's just me, but I would have thought that persistent villous atrophy akin to not-quite-complete mucosal healing would have been more pertinent to the expression of anxiety and depression. I say that from the point of view that micro nutrients (and specifically, the lack of them) seem to have some important relationships with mood states and related conditions (see here and see here) under other circumstances. I'd also mention that a patient with CD knowing that the gluten-free diet wasn't 'doing what it's supposed to' in relation to managing CD at a biological level might also be a cause for concern for them and possibly lead to more complicated 'issues'?

So what could be the reason for the Ludvigsson findings? Well, subject to independent replication of the findings and perhaps also looking at other variables potentially pertinent to the presentation of anxiety and depression in CD (see here for example based on the 'birds of an autoimmune feather' hypothesis), one might surmise a few things. First, that the biological expression of CD 'hides' underlying issues such as anxiety and depression, and only through (successful) treatment do such mood disorders become 'unmasked'. Anecdotally and without any supporting evidence, I remember back to some of my research days looking at gluten- and casein-free diets being used in the context of [some] autism, and how some parents / autistic people reported that the diet seemed to 'reveal' anxiety issues for example, at the costs of helping to resolve certain behavioural and somatic (bowel) issues they faced. Could similar mechanisms apply to CD bearing in mind the effect that dietary gluten removal has on gut barrier function?

Next possibility: gluten peptides. It's pretty well known that the gluten peptides - the intermediate compounds that form during the digestion of the gluten - have some important biological action insofar as them possessing potential opioid activity. The gluteomorphins as they're known, share similar structural data to other well known opioid compounds such as morphine. It's probably one of the reasons that we've had such an enduring relationship with such foodstuffs. Could the rise of mood disorders be related to such biochemistry? Y'know, removal of gluten peptides and the mucosal healing affecting transport to the wider central nervous system meaning that patients aren't getting 'their fix'?

One other possibility is also worth mentioning and investigating: Eyes should also perhaps turn to what other effects a dietary change such as gluten removal might have on physiology; specifically on the trillions of wee beasties that call our GI tract home: the gut microbiota. Does a healed mucosa have implications for the gut microbiota?

Questions, questions, questions...

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[1] Ludvigsson JF. et al. Anxiety after coeliac disease diagnosis predicts mucosal healing: a population-based study. Aliment Pharmacol Ther. 2018 Oct 4.

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"children with ASD who experience GI symptoms have an imbalance in their immune response"

The findings reported by Destanie Rose and colleagues [1] piqued my interest recently for a variety of reasons. Not only was there an emphasis on gastrointestinal (GI) issues in relation to autism (see here) but mention of the words 'microbiota composition' and 'impaired gut barrier function' make an important reference to something of a new triad in relation to [some] autism (see here).

First things first, as well as being another welcome research publication from the MIND Institute, the name Destanie Rose has appeared before on this blog with reference to maternal immune activation (MIA) and 'Old World monkeys' (see here). This work illustrated how infection during pregnancy can, under certain circumstances and at critical times, have a bearing on offspring development and behaviour; keeping in mind, that is, the possibility of logical fallacies (see here) when it comes to extrapolating from animal studies.

This latest time around, and including other notable names on the authorship list including Alessio Fasano (zonulin man) and Paul Ashwood (gut and immune system man), the focus shifted to immune function in the context of real life autism with the aim to "determine whether there are biological signatures in terms of immune dysfunction and microbiota composition in children with ASD with GI symptoms."

Four groups of children diagnosed with an autism spectrum disorder (ASD) participated in the study, including those with and without a diagnosis of ASD and with and without "current or previous GI symptoms." Both blood and stool samples were donated by study participants and subject to various analyses pertinent to assessing 'cytokine production' (cytokines are chemical signallers of the immune system) and ahem, the 'microbial composition' of poo(p) samples.

Results: those in the ASD + GI symptoms group showed "increased levels of mucosa-relevant cytokines including IL-5, IL-15 and IL-17" under "Toll-Like receptor (TLR)-4 stimulation" compared with those diagnosed with autism but with no bowel symptoms. TLR-4 is a protein that, as one of its duties, "plays a fundamental role in pathogen recognition and activation of innate immunity." Artificial stimulation of TLR-4 kinda mimics what would happen in real life as and when the body comes across a pathogen such as bacteria and needs to activate those immune defences.

Alongside other findings suggestive of "differences in microbiome composition between ASD and TD [typically developing] children with GI symptoms", authors also observed some interesting findings pertinent to impaired gut barrier function too. So: "The ASDGI also showed an over-representation of the gene encoding zonulin, a molecule regulating gut permeability, compared to the other groups." The gene in question is something called HP or Haptoglobin, and specifically HP2 which refers to a "common polymorphism consisting of two structural alleles: HP1 and HP2" [2]. As per the Vanuytsel paper [2], the HP2 allele is described as a risk allele for things like inflammatory bowel disease (IBD).

Bearing in mind that symptoms such as functional bowel issues (such as constipation and diarrhoea) are not necessarily the same as pathological bowel conditions such as the IBDs, I was interested in one of the figures included in the Vanuytsel paper on how HP2 links into gut permeability issues. In particular how "it is not unlikely that carriers of the zonulin gene (i.e., individuals with genotype HP21 or HP22) could possibly have an increased risk to develop IBD, because of the permeating effect of zonulin on the intestinal barrier." Zonulin has been something else of interest to this blog in the context of autism and so-called 'leaky gut' (see here) hence the interest in "a propensity to impaired gut barrier function which may contribute to their [gastrointestinal] symptoms and clinical outcome."

From what I gather, there was an over-representation of the HP2 allele (HP22 genotype) and under-representation of the HP1 allele in the ASDGI group examined in the Rose study, but things were not [statistically] completely cut-and-dried. This however, has to be set in the context of a seemingly increased risk of IBD as and when autism is diagnosed (see here).

What are the take-away messages from the Rose findings? Well bowel symptoms - functional bowel symptoms - occurring alongside autism probably have quite a complicated series of genetic and biological processes going on behind them. Both the mucosal immune system and the wider immune system are probably going to show 'some kind of relationship' to such chronic symptoms and, unsurprisingly, those trillions of wee beasties known as the gut microbiota are also probably involved/affected. The "propensity to impaired gut barrier function" associated with autism + bowel issues is also mentioned by Rose, and offers further testable hypotheses regarding the possibility of a gut-brain axis in relation to [some] autism (see here) and indeed, what measures might ease the pressures of such bowel issues. Also, whether bowel symptoms *might* show a connection to certain presented behaviour (see here) is another important area of further investigation...

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[1] Rose DR. et al. Differential immune responses and microbiota profiles in children with autism spectrum disorders and co-morbid gastrointestinal symptoms. Brain, Behavior, and Immunity. 2018. March 20.

[2] Vanuytsel T. et al. The role of Haptoglobin and its related protein, Zonulin, in inflammatory bowel disease. Tissue Barriers. 2013;1(5):e27321.

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Antibodies against gluten in autism don't correlate with leaky gut markers

The paper by Jan Józefczuk and colleagues [1] provided some intriguing observations pertinent to quite a few topics previously discussed on this blog. Not only was there mention of anti-gliadin antibodies (AGA) and more specifically the finding that increased IgG-AGA was found in a quarter of their 77 participants with autism included for study, but also the important point: "An increased production of antibodies related to gliadin and neural TG6 [neural transglutaminase 6] in ASD [autism spectrum disorder] children is not related to serological markers of an impaired intestinal barrier."

It's worthwhile breaking down some of the details of the Józefczuk findings and what they might mean. I'll warn you that this is likely to be a bit of a long-read blog post so please, get comfy and read on...

So, AGA and more specifically, IgG-AGA represent the immune system 'recognising' gliadin, an important part of the protein gluten. IgG-AGA are typically found in many people diagnosed with the archetypal gluten-related autoimmune condition called coeliac (celiac) disease (although this measure is not considered diagnostic) but also alongside other more 'non-coeliac' gluten sensitivity conditions too (see here). The finding of elevated IgG AGA in cases of autism is by no means a new one (see here) (yes, this data came from the AGRE program [2] so no quibbling about the diagnosis of autism or anything like that). Other data has indicated that the presence of such antibodies seems to be a good reason to attempt a gluten-free diet (see here) which is music to my autism research ears (see here) and a good evidence-based reason to quiet down those who might 'challenge' such dietary intervention in the context of [some] autism. Then also is the idea that the presence of IgG AGA in conditions not totally unrelated to autism (see here) *might* play an important role in something like 'peripheral' inflammation [3] and whether the same could be true for [some] autism...

Next: "antibodies against neural transglutaminase 6 (TG6)" described by the authors as present in about 5% of their cohort is also an important finding. Turning up in a variety of different conditions [4] (although not yet considered 'mainstream' in certain quarters), some of the most interesting, and potentially relevant, labels where TG6 might be present include something called gluten ataxia [5], a neurological 'sign' characterised by a 'lack of voluntary coordination of muscle movements that includes gait abnormality.' Again, the data is compelling insofar as the use of a gluten-free diet as an intervention option [6] where gluten ataxia is diagnosed. With specific regards to autism and TG6 antibodies, I think the Józefczuk paper provides the first research outing for the two together (at least in a PubMed search). Other transglutaminase antibodies however, have been reported in the context of autism (see here for example) with the need for lots more investigations including with reference to the overlap between autism and coeliac disease (see here). At this point, I'll also note that gluten ataxia has not yet been linked to autism despite ataxia potentially showing some connection to some cases [7].

Moving on and we have the finding that: "Mean levels of zonulin and I-FABP [intestinal fatty acid binding proteins] in ASD [autism spectrum disorder] patients were similar to those found in healthy controls." Further: "Serum concentrations of zonulin and I-FABP showed no statistically significant association with antibody positivity." OK, zonulin is another topic of interest to this blog particularly in light of other recent findings with autism in mind (see here). Still the topic of considerable debate, zonulin has been described as "a biomarker of impaired gut barrier function for several autoimmune, neurodegenerative, and tumoral diseases" [8]. The data so far seems to indicate that gliadin - that component of gluten - 'induces' zonulin release [9] hinting that diet may be an important variable when it comes to 'impaired gut barrier function' otherwise known as intestinal hyperpermeability (or more imprecisely, leaky gut). I-FABP is something I'm a little less sure about in any context. It has been mentioned in the peer-reviewed research arena with autism in mind [10] but I can claim not expertise on this specific marker.

The Józefczuk findings report that zonulin levels in their cohort with autism were similar to "to those found in healthy controls" which is contrary to those previous findings in autism published by Erman Esnafoglu and colleagues [11]. They (Esnafoglu et al) concluded that: "Serum zonulin levels were significantly higher in the patients with ASD (122.3 ± 98.46 ng/mL) compared with the healthy controls (41.89 ± 45.83 ng/mL). " Forgetting (but not excusing) the incorrect use of 'healthy controls' in that paper, there is something of a difference between the Esnafoglu and Józefczuk results. One could argue that this is simply reflective of 'conflicting' autism research more generally (see here) but one might also question things like the analytical ways-and-means of assaying for something like zonulin too (see here).

The observation that zonulin (and I-FABP) levels showed 'no statistically significant association with antibody positivity' whilst informative is something I've been thinking about quite a bit. I don't have any easy answers as to why they found what they found aside from assuming that such data is evidence for how "increased immune reactivity against gluten" might not be specifically related to "the effect of intestinal barrier abnormalities" in relation to autism. This relationship assumes that abnormal gut permeability is the route through which gluten fragments (peptides) gain access to the wider central nervous system (CNS) which then elicits that immune response. It is a little surprising that no relationship was found given that one of the ways that zonulin is released is ingestion of gliadin and the assumption that gluten needs to be present in the diet for antibodies to be formed against it. But there you go. I suppose one might entertain the possibility that zonulin as a biomarker of impaired gut barrier function might not be the optimal way of measuring gut barrier function and including other more direct measures [12] could be the way forward to resolving this issue further.

Either way, research on immunological responses to gluten and notions of atypical gut permeability in the context of 'some autism' are seemingly not going away any time soon. Indeed, even medical professionals are seemingly not adverse to prescribing a gluten-free diet in the context of [some] autism [13]...

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[1] Józefczuk J. et al. The Occurrence of Antibodies Against Gluten in Children with Autism Spectrum Disorders Does Not Correlate with Serological Markers of Impaired Intestinal Permeability. J Med Food. 2017 Oct 26.

[2] Lau NM. et al. Markers of Celiac Disease and Gluten Sensitivity in Children with Autism. PLoS One. 2013 Jun 18;8(6):e66155.

[3] Kelly DL. et al. Anti Gliadin Antibodies (AGA IgG) Related to Peripheral Inflammation in Schizophrenia. Brain Behav Immun. 2017 Oct 23. pii: S0889-1591(17)30476-2.

[4] Gadoth A. et al. Transglutaminase 6 Antibodies in the Serum of Patients With Amyotrophic Lateral Sclerosis. JAMA Neurol. 2015 Jun;72(6):676-81.

[5] Hadjivassiliou M. et al. Autoantibodies in gluten ataxia recognize a novel neuronal transglutaminase. Ann Neurol. 2008 Sep;64(3):332-43.

[6] Hadjivassiliou M. et al. Dietary treatment of gluten ataxia. Journal of Neurology, Neurosurgery, and Psychiatry. 2003;74(9):1221-1224.

[7] Ahsgren I. et al. Ataxia, autism, and the cerebellum: a clinical study of 32 individuals with congenital ataxia. Dev Med Child Neurol. 2005 Mar;47(3):193-8.

[8] Fasano A. Zonulin, regulation of tight junctions, and autoimmune diseases. Annals of the New York Academy of Sciences. 2012;1258(1):25-33.

[9] Clemente MG. et al. Early effects of gliadin on enterocyte intracellular signalling involved in intestinal barrier function. Gut. 2003 Feb;52(2):218-23.

[10] Pusponegoro HD. et al. Maladaptive Behavior and Gastrointestinal Disorders in Children with Autism Spectrum Disorder. Pediatr Gastroenterol Hepatol Nutr. 2015 Dec;18(4):230-7.

[11] Esnafoglu E. et al. Increased Serum Zonulin Levels as an Intestinal Permeability Marker in Autistic Subjects. Journal of Pediatrics. 2017; 188: 240-244.

[12] Bischoff SC. et al. Intestinal permeability – a new target for disease prevention and therapy. BMC Gastroenterology. 2014;14:189.

[13] Rubenstein E. et al. The prevalence of gluten free diet use among preschool children with autism spectrum disorder. Autism Res. 2017 Nov 20.

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Welcoming zonulin into autism research

I was VERY happy to read the paper published by Erman Esnafoglu and colleagues [1] suggesting that: "zonulin, which regulates intestinal permeability, plays a role in the development of symptoms of ASD [autism spectrum disorder]."

Zonulin - something that "can be used as a biomarker of impaired gut barrier function for several autoimmune, neurodegenerative, and tumoral diseases" [2] - is a compound that I've been interested in for a while on this and other blogs (see here). The primary reason for the interest is that connection to intestinal permeability and how 'leaky gut' may well show some relevance to some autism (see here and see here). The thing that was up-to-now missing from the research chatter about intestinal hyperpermeability and autism was the measurement of zonulin on the basis that elevated levels of zonulin show a connection to dietary elements such as gliadin (a facet of gluten) [3]. This is particularly relevant because previous data has observed a possible link between use of a gluten-free diet and a reduction in intestinal permeability in relation to autism [4]. All this is [peer-reviewed] research music to my ears (see here)...

Esnafoglu et al set about measuring serum levels of zonulin in 32 participants diagnosed with an autism spectrum disorder (ASD) compared with 33 not-autism controls. Yet again, the words 'healthy controls' are used by the authors to define the control group and yet again, the assumption is that those participants with autism are somehow 'unhealthy'. Researchers, please just call it what it is: not-autism controls (the term 'neurotypical' also tells us nothing about control groups either). Measurement of zonulin was via ELISA (enzyme-linked immunosorbent assay) and researchers also threw in a measure of autism severity based on use of the Childhood Autism Rating Scale (CARS).

Results: well, the results seemed to be in the expected direction: "Serum zonulin levels were significantly higher in the patients with ASD (122.3 ± 98.46 ng/mL) compared with the healthy controls (41.89 ± 45.83 ng/mL)." Authors also identified a fairly healthy correlation between the CARS score and zonulin levels. These results imply that issues with intestinal permeability - leaky gut - seem to be present in relation to at least some autism. A shocker, I know.

Obviously there is more research to do in this area; not least to increase the sample size, look at dietary intake/status as a function of zonulin measurement and explore the possibility that the genetics of zonulin production might also be *involved* in some autism [5]. I might add that other research on zonulin in relation to diagnoses not necessarily uncommon to autism might also be revealing (see here).

Insofar as what to do about elevations in zonulin as and when detected in cases of autism, well the dietary link to zonulin production implies that the horror that is a gluten-free (GF) diet might be something to consider. The suggestion of a 'bacterial link' to zonulin production also suggests another possible intervention target in these days of gut microbiomes and autism (see here) although I think we have to be slightly careful about the use of some preparations. There is also another avenue for research speculation based on the development of zonulin (receptor) inhibitors such as Larazotide acetate [6] (otherwise known as AT-1001). With no medical or clinical advice given or intended, the evidence base for this zonulin-affecting compound is looking promising [7] with much more to come...

In conclusion, zonulin has arrived on the autism research scene, and I'm expecting to see more peer-reviewed science on this topic in future times. Intestinal hyperpermeability, diet and [some] autism looks to be squarely back on the research agenda.

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[1] Esnafoglu E. et al. Increased Serum Zonulin Levels as an Intestinal Permeability Marker in Autistic Subjects. J Pediatrics. 2017. May 11.

[2] Fasano A. Zonulin, regulation of tight junctions, and autoimmune diseases. Annals of the New York Academy of Sciences. 2012; 1258(1) :25-33.

[3] Lammers KM. et al. Gliadin induces an increase in intestinal permeability and zonulin release by binding to the chemokine receptor CXCR3. Gastroenterology. 2008 Jul;135(1):194-204.e3.

[4] de Magistris L. et al. Alterations of the intestinal barrier in patients with autism spectrum disorders and in their first-degree relatives. J Pediatr Gastroenterol Nutr. 2010 Oct;51(4):418-24.

[5] Tripathi A. et al. Identification of human zonulin, a physiological modulator of tight junctions, as prehaptoglobin-2. Proc Natl Acad Sci U S A. 2009 Sep 29;106(39):16799-804.

[6] Fasano A. Intestinal Permeability and its Regulation by Zonulin: Diagnostic and Therapeutic Implications. Clinical gastroenterology and hepatology : the official clinical practice journal of the American Gastroenterological Association. 2012;10(10):1096-1100.

[7] Leffler DA. et al. Larazotide Acetate for Persistent Symptoms of Celiac Disease Despite a Gluten-Free Diet: A Randomized Controlled Trial. Gastroenterology. 2015; 148: 1311-1319.

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Esnafoglu, E., Cırrık, S., Ayyıldız, S., Erdil, A., Ertürk, E., Daglı, A., & Noyan, T. (2017). Increased Serum Zonulin Levels as an Intestinal Permeability Marker in Autistic Subjects The Journal of Pediatrics DOI: 10.1016/j.jpeds.2017.04.004

Gut barrier integrity meets blood-brain barrier integrity with autism in mind

"In the ASD [autism spectrum disorder] brain, there is an altered expression of genes associated with BBB [blood-brain barrier] integrity coupled with increased neuroinflammation and possibly impaired gut barrier integrity."

Although pretty enthused to see research linking names like Anna Sapone, Tim Buie and Alessio Fasano in the recent paper published by Maria Fiorentino and colleagues [1] (open-access), I was slightly less impressed with the use of the term 'the ASD brain' in their paper potentially joining two concepts that I've been quite interested in down my research years: gut barrier and blood-brain barrier function in the context of autism. Yes, I accept that those most precious of resources, donated brains from the deceased, represented some of the 'material' under scientific scrutiny, but if science has learned anything about autism down the years, it is that sweeping generalisations such as terms like 'the autism brain' don't reflect what the existing research tells us about the heterogeneity under the label. I might just as well use the term 'blogger brain' to denote some of my activities, but such a label tells you nothing about me aside from my pastime.

After that little rant, the paper from Fiorentino is an interesting one in that the goal was to "investigate whether an altered BBB and gut permeability is part of the pathophysiology of ASD." To do this, tissue from both brain and gastrointestinal (GI) tract donated by a small number of deceased and non-deceased participants who were diagnosed with autism, schizophrenia or nothing related (not-autism controls) were analysed "for gene and protein expression profiles." This work was undertaken on the basis of "the interconnectivity of the gut–brain axis, [that] suggests that inappropriate antigen trafficking through an impaired intestinal barrier, followed by passage of antigens or activated immune complexes through a permissive blood–brain barrier (BBB), can be part of the chain of events leading to neuroinflammation and thereby subsequent disease." I might add that the use of the word 'disease' in that sentence is, I think, aiming to describe the physiological effects of 'leaky barriers' not the diagnosis of autism. It is unfortunate however that 'disease' still continues to be banded around in the context of autism [2].

I think it's important to stress that the Fiorentino study was in effect two studies: one that looked at brain samples from one participant group who had died, and one that looked at GI samples from those who were still living (at the time of sample collection) and who presented with "GI symptoms undergoing esophagogastroduodenoscopy (EGD) for clinically indicated reasons." This was not a study where biological samples - brain and gut - came from the same person but rather a mash-up. Keep that in mind for now. The sorts of genes that were focused in on were those "associated with the formation, integrity, and function of the BBB and neuroinflammation" and included the claudins and something called MMP-9 and MMP-2 that have been discussed previously on this blog (see here) with leaky barriers in mind. The key words are 'barrier integrity' when it comes to the list of compounds that were under inspection.

Results: well it was good to see the authors list details of each of the participants from which tissue were used in their study. Brain tissue from the deceased with autism for example, is subject to quite a few factors that can influence the outcome of any results obtained; not least whether specific comorbidity accompanied their autism diagnosis and the nature of their death. Indeed, looking through the various case report numbers, I'm struck by how young many participants, particularly those diagnosed with autism, were at the time of their death. This ties into other discussions and debates (see here).

"Our molecular analysis of the BBB integrity and function shows an altered BBB in the ASD subjects evaluated." This was evidenced by elevations in the gene expression of MMP-9 and its proposed connection to disturbances of BBB integrity. Further: "Of the four claudins (i.e., CLDN-1, -3, -5 and -12) that to date are thought to be incorporated in the BBB... we found that two were significantly more expressed in the ASD brain as compared in HC [healthy controls]." Once again I might suggest the term 'healthy controls' is not an inappropriate one when it comes to determining not-autism or not-schizophrenia.

Then to analysis of those [independent] gut biopsy samples: "results, showing increased expression levels of pore-forming (66% of the ASD samples) and decreased levels of barrier-forming (75% of the ASD samples) TJ [tight junction] components in the duodenal samples, suggest an impaired gut barrier and serve as a proof of concept to support the hypothesis of a gut–brain axis dysfunction in a subgroup of ASD patients." So, those compounds linked to making the gut barrier more 'leaky' were seemingly increased in expression, and those linked to making the gut barrier less 'leaky' were reduced in quite a few of the samples from those diagnosed with autism. Mmm...

There is quite a bit more science included in the Fiorentino study but I think I've gone on long enough in this post. Suffice to say that the whole gut-brain axis thing with autism in mind gets a boost but more work is indicated, not least with larger sample groups and perhaps combining tissues from gut and brain from the same person. I would also like to see a little more done on this topic with some 'interventions' in mind, based on the other autism research that potentially links the authors (see here). Drawing for example, on a paper written by Prof Fasano titled: 'Zonulin, regulation of tight junctions, and autoimmune diseases' [3] suggesting that "gliadin, a storage protein present in wheat and that triggers celiac disease in genetically susceptible individuals, also affect the intestinal barrier function by releasing zonulin" one might see how far from being a set-in-stone state of affairs, dietary changes for some on the autism spectrum, might actually set in motion a host of biological changes pertinent to this area of work. And such changes might not be just confined to accepted gluten-related conditions either...

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[1] Fiorentino M. et al. Blood–brain barrier and intestinal epithelial barrier alterations in autism spectrum disorders. Molecular Autism. 2016; 7:49.

[2] Simms MD. When Autistic Behavior Suggests a Disease Other than Classic Autism. Pediatr Clin North Am. 2017 Feb;64(1):127-138.

[3] Fasano A. Zonulin, regulation of tight junctions, and autoimmune diseases. Annals of the New York Academy of Sciences. 2012;1258(1):25-33.

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Fiorentino, M., Sapone, A., Senger, S., Camhi, S., Kadzielski, S., Buie, T., Kelly, D., Cascella, N., & Fasano, A. (2016). Blood–brain barrier and intestinal epithelial barrier alterations in autism spectrum disorders Molecular Autism, 7 (1) DOI: 10.1186/s13229-016-0110-z

More scientific flesh on the bones of non-coeliac gluten/wheat sensitivity

I was really, really pleased to read the paper by Melanie Uhde and colleagues [1] (open-access) I don't mind telling you. Covering a topic close to my blogging and research heart - sensitivity to wheat or gluten but not coeliac disease - the authors provide some much needed scientific clarification when it comes to how gluten or wheat might impact on some of those "who reported symptoms in response to wheat intake and in whom coeliac disease and wheat allergy were ruled out." Some media interest in the paper can also be seen here.

With an authorship list including some of the great and good on this issue (see here for example) researchers included 80 participants presenting with non-coeliac wheat sensitivity (NCWS) according to "criteria recently proposed by an expert group" [2]. These NCWS participants reported "experiencing intestinal and/or extraintestinal symptoms after ingestion of gluten-containing foods, including wheat, rye or barley. The reported symptoms in all subjects improved or disappeared when those foods were withdrawn for a period of 6 months, and recurred when they were re-introduced for a period of up to 1 month." All 80 provided serum samples for analysis that were compared with similar samples from 40 participants with "biopsy-proven active coeliac disease" and 40 samples from asymptomatic controls on a non-restrictive diet.

The sort of information sought from those serum samples included quite a bit. Not only were "established markers" of coeliac disease (CD) assayed for - including IgA antibody to TG2 - but various immunological markers towards gluten were also included for study. Based also on the idea that "intestinal cell damage and systemic immune response to microbial components" might be an important feature of NCWS, researchers also markers associated with "compromised intestinal epithelial barrier integrity."

Results: well, as per the media interest in this paper: "The findings suggest that these individuals [with NCWS] have a weakened intestinal barrier, which leads to a body-wide inflammatory immune response."

A few further details are worthwhile discussing. First, the genetics of coeliac disease (those DQ2 and/or DQ8 heterodimers) were present in about a quarter of those with NCWS "a rate not substantially different than in the general population." Second, most of those with NCWS did not show the characteristic mucosal signs of CD as per the Marsh gradings (0 or 1) throughout the cohort. This was in direct contrast to the CD participants who all "expressed HLA DQ2 and/or DQ8 and presented with Marsh 3 grade intestinal histological findings." The conclusion: CD and NCWS participants are not one and the same (just in case you needed telling).

Next: "Serum levels of both LBP [lipopolysaccharide (LPS)-binding protein (LBP)] and sCD14 were significantly elevated in individuals with NCWS in comparison with patients with coeliac disease and healthy individuals." This implies that there is 'systemic immune activation' on-going in those participants with NCWS not seen to the same extent in the other groups. These findings were also complemented by results indicative of that compromised intestinal epithelial barrier integrity previously discussed. The final picture emerging being one where NCWS participants seem to be in a state of 'immune activation' "linked to increased translocation of microbial and dietary components from the gut into circulation, in part due to intestinal cell damage and weakening of the intestinal barrier." I might add that some smaller scale analysis of serum samples from those NCWS participants "both before and after 6 months of a self-monitored diet free of wheat, rye and barley" suggested "a significant decline in the markers of immune activation and gut epithelial cell damage, in conjunction with the improvement of symptoms."

And rest.

For those as interested in this area of research as I am, I'm sure that you can understand my happiness in seeing the Uhde results and what it might mean for many, many people who've been perhaps been 'fobbed off' down the years with regards to their gluten ills. I can't help but see a possible connection between these findings and others reported with autism in mind for example (see here and see here). The added suggestion that 'intestinal cell damage' might be a feature of NCWS also possibly ties in with all that talk about 'leaky gut' and some autism (see here) but I don't doubt it may go well beyond just [some] autism [3]. Not looking so tree-hugging now eh?

Of course there is more to do in this area: "Further research is needed to investigate the mechanism responsible for the intestinal damage and breach of the epithelial barrier, assess the potential use of the identified immune markers for the diagnosis of affected individuals and/or monitoring the response to specific treatment strategies, and examine potential therapies to counter epithelial cell damage and systemic immune activation in affected individuals." I might also add in a role for those trillions of wee beasties that call our gut home (the gut microbiota) as potentially also being a target for further scientific research too (see here for example).

I await further studies...


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[1] Uhde M. et al. Intestinal cell damage and systemic immune activation in individuals reporting sensitivity to wheat in the absence of coeliac disease. Gut. 2016. July 25.

[2] Catassi C. et al. Diagnosis of Non-Celiac Gluten Sensitivity (NCGS): The Salerno Experts’ Criteria. Nutrients. 2015;7(6):4966-4977.

[3] Whiteley P. Nutritional management of (some) autism: a case for gluten- and casein-free diets? Proc Nutr Soc. 2015 Aug;74(3):202-7.

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Uhde, M., Ajamian, M., Caio, G., De Giorgio, R., Indart, A., Green, P., Verna, E., Volta, U., & Alaedini, A. (2016). Intestinal cell damage and systemic immune activation in individuals reporting sensitivity to wheat in the absence of coeliac disease Gut DOI: 10.1136/gutjnl-2016-311964

Increased microbial translocation in ME/CFS

"The cause of ME/CFS [myalgic encephalomyelitis/chronic fatigue syndrome] is unknown, but gut dysbiosis could be contributing to some of the symptoms and their severity. Developing therapeutic interventions aimed at reducing local inflammation, restoring gastrointestinal tract immunity and integrity and modifying the intestinal microbiome may ameliorate ME/CFS symptoms in a number of affected patients."

Those were the important conclusions reported by Ludovic Giloteaux and colleagues [1] (open-access) who "profiled gut microbial diversity by sequencing 16S ribosomal ribonucleic acid (rRNA) genes from stool as well as inflammatory markers from serum for cases (n = 48) and controls (n = 39)." Authors recount how all 'cases' (participants) fitted the "Fukuda diagnostic criteria" for CFS/ME but "most, perhaps all, also fit the description of SEID [Systemic Exertion Intolerance Disease]." We're also told that a majority of participants with ME/CFS "self-reported gastrointestinal disturbances such as constipation, diarrhea, or intestinal discomfort" something perhaps not unfamiliar to the peer-reviewed research domain (see here).

Looking at inflammatory markers as well as the composition and diversity of those trillions of wee beasties that call us home (the gut microbiome), Giloteaux et al reported some important differences between their groups that might even be considered 'diagnostic' at some point in the future (emphasis on 'some point'). "[The] gastrointestinal tract of ME/CFS  patients is a pro-inflammatory environment" is another of their observations; indeed, based on the idea that: "Abnormal immune activation can be caused by translocation of microbes from an inflamed gut" and reporting elevations in some of the blood markers potentially pertinent to this process. Said microbial translocation (MT) was evidenced by: "(i) significantly raised levels of plasma LPS [lipopolysaccharide] and (ii) significantly higher levels of sCD14 [soluble CD14] and LBP [LPS-binding protein], as indicators of direct LPS stimulation." Interestingly however: "Levels of hsCRP [high-sensitivity C-reactive protein] were higher in the ME/CFS population in comparison to healthy controls... but the difference was not statistically significant."

Examination of stool samples from study participants also found some potentially important differences between the groups as "less diversity as well as increases in specific species often reported to be pro-inflammatory species and reduction in species frequently described as anti-inflammatory" were found in the ME/CFS group. Of particular note were "lower levels of the genus Faecalibacterium, a member of the Ruminococcaceae in the ME/CFS population" and that "Proteobacteria were more abundant in ME/CFS patients than in controls." Minus any sweeping generalisations, such combined findings have been reported in cases of inflammatory bowel disease (IBD) among other things. Utilising a machine-learning approach (something we've seen before on this blog) authors were also "mostly successfully classified into healthy and ME/CFS groups" on the basis of the inflammatory and microbiome data with a little more investigation required.

This is of course not the first time that the gut microbiome has been 'implicated' in cases of ME/CFS (see here). The application of the 'yuck factor 10' that is the faecal microbiota transplantation as one effort to alter the gut microbiome in cases of ME/CFS has also been mentioned too (see here). These latest results add to the interest and indeed, the idea that the gut might be a central organ of either cause or effect when it comes to at least some cases of ME/CFS (see here and see here). But I might also add there is more to do in this area. Giloteaux et al talk a lot about gut barrier integrity as being implicated but didn't directly measure permeability or by how much...

Finally, I do think due credit should be given to some of the research pioneers upon which the Giloteaux findings are based. I'm thinking specifically of Michael Maes of NIOF fame (see here) who has been quite consistently talking about "increased translocation of LPS from gram negative bacteria with subsequent gut-derived inflammation" in cases of CFS/ME and importantly, what could be potentially done about it [2]. It appears that replicative science might indeed be on his, and his research teams', side. And he just keeps going (see picture).

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[1] Giloteaux L. et al. Reduced diversity and altered composition of the gut microbiome in individuals with myalgic encephalomyelitis/chronic fatigue syndrome. Microbiome. 2016; 4: 30.

[2] Maes M. & Leunis JC. Normalization of leaky gut in chronic fatigue syndrome (CFS) is accompanied by a clinical improvement: effects of age, duration of illness and the translocation of LPS from gram-negative bacteria. Neuro Endocrinol Lett. 2008 Dec;29(6):902-10.

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Giloteaux L, Goodrich JK, Walters WA, Levine SM, Ley RE, & Hanson MR (2016). Reduced diversity and altered composition of the gut microbiome in individuals with myalgic encephalomyelitis/chronic fatigue syndrome. Microbiome, 4 (1) PMID: 27338587

Ehlers-Danlos syndrome (EDS) associated with autism?

Ehlers-Danlos syndrome (EDS) refers to a collection of conditions also headed under the label of connective tissue disorder. EDS affects the 'cellular glue' that basically gives biological tissues their shape and stability such as cartilage. There are various types of EDS and symptoms can vary from person-to-person but one of the most frequent characteristics of the syndrome is joint hypermobility.

I've speculated a few times on this blog about the possibility that EDS and/or joint hypermobility might be yet another comorbidity (albeit rare) to look for when it comes to at least some autism (see here). My reasoning was based on the suggestion that joint hypermobility might not be uncommon for some people on the autism spectrum [1] set against a backdrop of various behavioural/psychiatric diagnoses perhaps being over-represented among cases of such connective tissue disorder (see here).

The findings reported by Martin Cederlöf and colleagues [2] (open-access) add to the scientific interest in this area with their observation that: "Individuals with EDS and hypermobility syndrome are at increased risks of being diagnosed with psychiatric disorders." Autism or rather autism spectrum disorder (ASD) figures in their various conditions screened for among those with EDS and hypermobility syndrome; said data coming once again from one of those very useful Scandinavian population registries ("the Swedish Patient Registry"). With one Jonas F. Ludvigsson on the authorship list - he of 'not quite coeliac disease but something else gluten-related potentially linked to some autism' and quite a lot more besides - researchers looked at some 1700 individual diagnosed with EDS compared to 17,000 asymptomatic controls to calculate any risk of "autism spectrum disorder (ASD), bipolar disorder, attention deficit hyperactivity disorder (ADHD), depression, attempted suicide, suicide and schizophrenia." They additionally report data on "10,019 individuals with hypermobility syndrome (67 % females) and 11,082 hypermobility syndrome siblings."

Results: well, those with EDS did seem to be at some advanced risk of most of the behavioural/psychiatric conditions screened for particularly autism (ASD) and attention-deficit hyperactivity disorder (ADHD) compared with controls. This risk also seemed to extend to those diagnosed with hypermobility syndrome compared with matched controls (+100,000 participants); ADHD particularly standing out in that cohort (RR 5.8, 95 % CI 5.0–6.7). Interestingly the advanced risk of behavioural or psychiatric diagnosis occurring alongside also seemed to extend to siblings of those with EDS in terms of ADHD and labels such as depression and extreme events such as suicide (completion). In short, there appears to be quite a bit to see when it comes to the behavioural and/or psychiatric correlates of EDS and hypermobility syndrome. I might however again reiterate that the absolute numbers of people with co-occurring EDS and autism (52/1771 = 2.9%) or hypermobility syndrome and autism (161/10019  =1.6%) for example, indicate that such issues are not exactly widespread among the population.

I know some people might be getting a little tired of hearing me go on and on about how a diagnosis of autism seems to be protective of nothing in terms of comorbid conditions/states and how screening for the various comorbidity potentially present should perhaps be preferentially offered. Yes, resources are stretched, money is getting tighter all the time and the rates of autism (for whatever reason) seem to be only going one way... up. But, entertaining the idea that comorbidity might in some cases be actually pretty disabling to those on the autism spectrum (think anxiety for example) and that the label of autism does seem to result in some significant health inequalities, the onus really should be on setting up some sort of 'screening checklist' as and when an autism diagnosis is handed out. Indeed, I might just end up doing that myself one day...

Although Cederlöf et al don't do much speculating about why behavioural/psychiatric comorbidity might be linked to EDS or hypermobility syndrome, there is a pressing need to establish any shared pathways. In these days of plural autisms (see here) and specifically the idea that particular genetic conditions might manifest autism+ (see here) it wouldn't be difficult to devise further research looking at possible common genetic threads where autism and EDS for example, represent one possible phenotype. Beyond just genetics however, I'm also minded to bring in another possible example where connective tissue disorder might overlap with autism: the concept of a hyper-permeable intestinal barrier (yes, the so-called leaky gut). I know, I know, for some people the 'dread' that is leaky gut brings about furrowed brows and rolling eyes, but the scientific reality is that for some on the autism spectrum, this may be an important concept (see here) growing, as it is, in other circles of medicine too (see here). Could intestinal hyperpermeability be a feature of EDS/joint hypermobility syndrome in cases of autism? Well, I'd really like to see questions like this further explored in light of what it known about gastrointestinal issues accompanying joint hypermobility syndrome [3] and indeed, whether there may be other interventions to consider (see here) as a result [4]...

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[1] Shetreat-Klein M. et al. Abnormalities of joint mobility and gait in children with autism spectrum disorders. Brain Dev. 2014 Feb;36(2):91-6.

[2] Cederlöf M. et al. Nationwide population-based cohort study of psychiatric disorders in individuals with Ehlers–Danlos syndrome or hypermobility syndrome and their siblings. BMC Psychiatry. 2016; 16: 207.

[3] Fikree A. et al. A prospective evaluation of undiagnosed joint hypermobility syndrome in patients with gastrointestinal symptoms. Clin Gastroenterol Hepatol. 2014 Oct;12(10):1680-87.e2.

[4] Hong Y. et al. Salutary effects of melatonin combined with treadmill exercise on cartilage damage. J Pineal Res. 2014 Aug;57(1):53-66.

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Cederlöf, M., Larsson, H., Lichtenstein, P., Almqvist, C., Serlachius, E., & Ludvigsson, J. (2016). Nationwide population-based cohort study of psychiatric disorders in individuals with Ehlers–Danlos syndrome or hypermobility syndrome and their siblings BMC Psychiatry, 16 (1) DOI: 10.1186/s12888-016-0922-6

No unique patterns of gut issues in autism? Headline fail...

"This study supports the observation that children with autism who have symptoms of gastrointestinal disorders have objective findings similar to children without autism. Neither non-invasive testing nor endoscopic findings identify gastrointestinal pathology specific to autism, but may be of benefit in identifying children with autism who have atypical symptoms."

So concluded Rafail Kushak and colleagues [1] (them of "Lactase deficiency not associated with intestinal inflammation or injury is common in autistic children and may contribute to abdominal discomfort, pain and observed aberrant behavior" [2]) who undertook some important work around the topic of gastrointestinal (GI) issues being over-represented in cases of autism (see here). Some media on their recent findings can be read here (see here).

Looking at the results of 61 children diagnosed with autism and presenting with GI issues and data from 50 non-autistic individuals also being assessed for GI problems, researchers examined whether there were any differences between the groups on a range of measures including disaccharidase activity, intestinal inflammation and gut permeability (the so-called 'leaky gut'). They reported finding some discrepancies between the groups - including "mild levels of mucosal inflammation on intestinal biopsy" for some of those with autism -  but nothing that seemed to point to a 'GI fingerprint' specifically relevant to just autism. They concluded that where GI issues appear alongside autism, the same level of assessment and care should be afforded as it is when GI issues are present outside of autism. Tim Buie, one of the study authors, had said as much quite a few years back.

I would draw attention to a few important points included in the Kushak study. First, are the participant groups. This was a study comparing children with and without autism who were both under investigation following the presentation of GI issues. They were not comparing children with autism with GI issues with non-autistic children without gut issues. I say this just in case anyone assumes that the findings point to no significant gut issues being identified in those with autism. That is absolutely not the case. Headlines might need some adjustment.

Second, the results reported are to some degree at odds with other findings published by independent groups - specifically those reported by Stephen Walker and colleagues [3] (see here for my take). Although perhaps not exactly overlapping in terms of methods and outcomes, Walker et al concluded that their data was evidence that "ASDGI children have a gastrointestinal mucosal molecular profile that overlaps significantly with known inflammatory bowel disease (IBD), yet has distinctive features that further supports the presence of an ASD-associated IBD variant, or, alternatively, a prodromal phase of typical inflammatory bowel disease." I might add that at the time of writing this post and despite the Walker findings being published some 3 years ago, no-one has taken up the research gauntlet to try and replicate/challenge the Walker publication. That IBD might be over-represented when a diagnosis of autism is received is also an important point to make (see here).

Finally, mention of the words "leaky gut" in the Kushak report are a continued welcome sign. That measurement via "rhamnose/lactulose test and measured by HPLC-MS" did not appear to differentiate kids with autism with GI issues vs, kids without autism with GI issues is an important addition to the debate in this area. I know discussions of intestinal permeability with autism in mind can furrow brows in certain quarters but there is a growing recognition that (a) this is a real phenomenon (see here) and (b) for at least some people on the autism spectrum, gut permeability issues are present (see here). That gut permeability issues might be a 'later life event' when detected in 'some' autism (see here) is also worth re-iterating as is the idea that 'treating' gut permeability might be something that many people are already doing without even knowing it (see here).

Now, about that study on the use of dietary intervention for children with autism WITH bowel issues...

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[1] Kushak RI. et al. Evaluation of Intestinal Function in Children with Autism and Gastrointestinal Symptoms. J Pediatr Gastroenterol Nutr. 2016 Feb 20.

[2] Kushak RI. et al. Intestinal disaccharidase activity in patients with autism: effect of age, gender, and intestinal inflammation. Autism. 2011 May;15(3):285-94.

[3] Walker S. et al. Identification of unique gene expression profile in children with regressive autism spectrum disorder (ASD) and ileocolitis. PLoS ONE. 2013; 8: e58058.

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Kushak RI, Buie TM, Murray KF, Newburg DS, Chen C, Nestoridi E, & Winter HS (2016). Evaluation of Intestinal Function in Children with Autism and Gastrointestinal Symptoms. Journal of pediatric gastroenterology and nutrition PMID: 26913756