Lactobacillus (L.) reuteri and mouse-modelled autism: spotlight on the vagus nerve?

I am a little late getting to the findings reported by Martina Sgritta and colleagues [1] but I eventually arrived at them. As per the title of this post - "Lactobacillus (L.) reuteri and mouse model autism: spotlight on the vagus nerve?" - there were a number of important elements to this research covering mouse-modelled autism, the "gut-microbiota-brain axis", and something called the vagus nerve. Pretty good fodder for this blog by all accounts, given some past discussions (see here) including mention of previous research from some of the Sgritta paper co-authors (see here).

So, continuing a theme from this research group suggesting that, in mice at least, some pregnancy 'risk factors' for autism might have a microbial connection [2], authors set out to examine whether the inclusion of a specific bacterial species called Lactobacillus reuteri or L. reuteri for short might have some important effect on the social behaviour of a mouse model of autism. L. reuteri has been the source of quite a bit of study down the years [3] as a function of it's antimicrobial activity and connection to inflammatory conditions. Outside of the Baylor College group research, this bacterial species has also been talked about with autism in mind [4] in other studies, as per conclusions like: "This study identifies bacterial species that are sensitive to an autism-related mutation." I'll say no more on that study for now aside from offering a viewpoint from elsewhere on the web.

Alongside their observation that "treatment with L. reuteri selectively rescues social deficits in genetic, environmental, and idiopathic ASD [autism spectrum disorder] models" Sgritta et al also put a little scientific flesh on what underlying mechanism(s) might be pertinent to such 'rescuing' of social issues. You might think it was something to do with the contribution of L. reuteri to the gut microbiome of the [mouse] host? Well, yes and no, as authors highlighted how "L. reuteri acts in a vagus nerve-dependent manner" so bringing in the notion that bacteria in the gut *talk to* the brain (or the wider central nervous system) via the vagus nerve. The paper by Bruno Bonaz and colleagues [5] provides as good an explanation as any of how bacteria talk to the brain and what this means for the "gut-microbiota-brain axis." Interestingly too, authors mention how when the vagus nerve was 'disrupted' in said mouse-modelled autism, so the the gut-microbiota-brain link was also disrupted, and onward that L. reuteri didn't seemingly work as well at rescuing those social issues. They also talk about a role for oxytocin receptors in their findings similar to their last research occasion, but I'm going to leave that for now. All I will say is that oxytocin has also been mentioned in other autism research circles (see here).

Obviously, there are caveats to the Sgritta findings; not least that mouse-modelled autism is just mouse-modelled autism and probably not totally representative of real-life human autism (see here). Generalisations of the social behaviour of mice raised and living under laboratory conditions to people (children and adults) traversing the big, wide real world always require a degree of caution.

But I am interested in this area and would like to see more study done on the "gut-microbiota-brain axis" with autism in mind. Given that L. reuteri is freely available to anyone and everyone and seems to have quite a good safety record, I'd perhaps suggest that a clinical trial could be something that a young, upcoming researcher or research group might possibly want to consider exploring...

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[1] Sgritta M. et al. Mechanisms Underlying Microbial-Mediated Changes in Social Behavior in Mouse Models of Autism Spectrum Disorder. Neuron. 2018 Dec 3. pii: S0896-6273(18)31009-2.

[2] Buffington SA. et al. Microbial Reconstitution Reverses Maternal Diet-Induced Social and Synaptic Deficits in Offspring. Cell. 2016 Jun 16;165(7):1762-1775.

[3] Mu Q. et al. Role of Lactobacillus reuteri in Human Health and Diseases. Front Microbiol. 2018;9:757. 

[4] Tabouy L. et al. Dysbiosis of microbiome and probiotic treatment in a genetic model of autism spectrum disorders. Brain Behav Immun. 2018 Oct;73:310-319.

[5] Bonaz B. et al. The Vagus Nerve at the Interface of the Microbiota-Gut-Brain Axis. Front Neurosci. 2018;12:49. 

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Induced labour and autism (again)

"In this nationwide sample of live births we observed no association between induction of labor and offspring ASD [autism spectrum disorder] within sibling comparison. Our findings suggest that concern for ASD should not factor into the clinical decision about whether to induce labor."

So said the findings reported by Anna Sara Oberg and colleagues [1] supposedly providing some reassurance to mums-to-be and other groups around the likelihood of offspring autism when birth or labour has to be induced. Based on the analysis of one of those oh-so important Scandinavian health registries, researchers followed all the live births recorded in Sweden between 1992 and 2005 looking for signs that labour was induced. As per some media discussion of the study: "Methods to induce labor include rupturing of membranes, mechanical or pharmacological ripening of the cervix, and administration of oxytocin, either used alone or in combination." They also followed the cohort, numbering above a million offspring, looking for recorded diagnoses of ASD in children and, taking into account "a wide range of measured confounders" examined whether induced labour might elevate the risk of offspring ASD.

The headlines suggesting 'no link' between induced labour and offspring autism don't however actually tell the full story of these findings. When taking into account the full cohort - "1 362 950 births"- there did seem to be a slight increased risk of offspring autism associated with labour induction. This association persisted "after adjustment for measured potential confounders" albeit to an even lesser degree. The 'no link' headlines seemed to have focused on further analysis where siblings, one who was induced, one who was not, were compared with regards to autism rates: "thus accounting for all environmental and genetic factors shared by siblings, labor induction was no longer associated with offspring ASD."

I've talked about labour induction and autism risk before on this blog (see here) based on findings [2] that Oberg et al were knowledgeable about and that had reported something of an increased risk based on the analysis of over half a million births in a part of the United States. Personally, I do think there is a little more to see in this area than has hitherto been uncovered. The reasons for induction is something to focus on as per the observations that issues such as pre-eclampsia and gestational diabetes are mentioned and the body of research linking such factors to offspring autism risk (see here and see here for examples). That induction also might mean use of oxytocin (the cuddle hormone!) is something else that perhaps require further investigations too. Without trying to scaremonger, I do wonder whether further thought might be needed based on the findings reported by Leffa and colleagues [3] with oxytocin in mind.

The take-away message: induced labour is pretty unlikely to 'cause' offspring autism but beware of sweeping generalisations and media headlines...

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[1] Oberg AS. et al. Association of Labor Induction With Offspring Risk of Autism Spectrum Disorders. JAMA Pediatr. 2016. 25 July.

[2] Gregory SG. et al. Association of autism with induced or augmented childbirth in North Carolina Birth Record (1990-1998) and Education Research (1997-2007) databases. JAMA Pediatr. 2013 Oct;167(10):959-66.

[3] Leffa DD. et al. DNA damage after chronic oxytocin administration in rats: a safety yellow light? Metab Brain Dis. 2016 Aug 3.

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Oberg, A., D’Onofrio, B., Rickert, M., Hernandez-Diaz, S., Ecker, J., Almqvist, C., Larsson, H., Lichtenstein, P., & Bateman, B. (2016). Association of Labor Induction With Offspring Risk of Autism Spectrum Disorders JAMA Pediatrics DOI: 10.1001/jamapediatrics.2016.0965

Lactobacillus reuteri rescuing [mouse] social behaviours: relevance to autism?

Continuing a recent 'probiotic theme' on this blog I've decided to talk a little about the study results reported by Shelly Buffington and colleagues [1] on how a "single species of gut bacteria can reverse autism-related social behavior in mice." I say 'talk about' but my conversations on this topic should be viewed in light of what others have also said about this study (see here for example) including the lead author (see here).

To summarise the findings: authors started from the idea that maternal obesity during pregnancy might have some implications for offspring in terms of their risk of "neurodevelopmental disorders including autism spectrum disorder (ASD)." It's something that has been covered before on this blog (see here) including the idea that inflammation or response to inflammation in-utero might be an important part of any risk mechanism (see here).

Conversations then progressed towards the possibility that the gut microbiome might play a role in that elevated risk of offspring autism following pregnancy obesity. To test this theory out, researchers fed female mice a high fat or 'normal diet' for 8 weeks, paired them for mating and gave all their offspring a regular diet. They studied social behaviour of offspring mice and observed that "MHFD [maternal high-fat diet] offspring had impaired sociability and showed no preference for social novelty."

To examine whether those mouse social behaviours were linked to the gut microbiome, researchers looked at the "bacterial composition and community structure in the feces" of offspring mice to ascertain any differences. They did find differences; indeed in one write-up of the study the authors note: "We found a clear difference in the microbiota of the two maternal diet groups." Could such bacterial differences account for the social differences noted between the groups? Quite possibly as Buffington et al reported that "co-housing one MRD [maternal regular diet] with three MHFD offspring was sufficient to rescue both the social behaviors and microbiota phylogenetic profile of MHFD offspring." Further, researchers transplanted the faecal microbiota from the MRD and MHFD offspring into germ-free mice providing "causal evidence that an imbalanced microbial ecology in the mice born to mothers on a high-fat diet is responsible for their social deficits."

Then came a big question: what was it about the maternal high-fat diet offspring microbiome that might be 'responsible' for the social issues observed? The answer or at least one answer: "L. reuteri [Lactobacillus reuteri] was the most drastically reduced (>9-fold) in the MHFD microbiota population, compared to the MRD microbiota." Subsequent addition of L. reuteri to the drinking water of MHFD offspring was instigated and: "Remarkably, treatment with L. reuteri significantly improved sociability and preference for social novelty in MHFD offspring."

As if all that wasn't enough researchers also looked at the old gut-brain axis and subsequently noted that: "L. reuteri treatment restores oxytocin levels, VTA [ventral tegmental area] plasticity and social behaviors." Oxytocin has something of an interesting possible connection to [some] autism (see here).

And rest.

As you can perhaps appreciate, this piece of research is fairly comprehensive both in terms of the methodologies used and also the findings in relation to maternal pregnancy obesity, offspring social behaviour, gut microbiome and the gut-brain axis. Certainly quite compelling evidence for some kind of effect including the concept of foetal programming allied to the idea of possible intervention.

Of course you'd be right to question whether the processes described in this mouse model would necessarily map on to the human experience and indeed the very heterogeneous autism spectrum characterised by [variable] issues with social affect for example. Similar questioning is asked of all animal studies trying to model the complexities of autism (see here). But added to other research where mouse modelling of autism 'deficits' has been to some degree 'changed' as the result of the addition of a particular bacterial species (see here) there is some reason for potential excitement. More so when one considers other research on the gut microbiome in relation to specific preparations potentially modifying the risk of 'neurospychiatric disorder' (see here) for example, and potentially affecting mood and/or behaviour (see here). Don't even get me started on toddler temperament being linked to the inner workings of the gut (see here) minus any hype.

But just before sales of Lactobacillus reuteri increase markedly there is further research to be done. Not least is the translation of elements of the Buffington research into studies of humans. Set within the idea that mapping exactly what kinds of wee beasties are residing in the gut is now fairly commonplace and has already stretched into autism research (see here) I would have thought that looking for the presence or absence of L. reuteri in certain groups (and sub-groups) on the autism spectrum and beyond should be fairly easy to do. If and when issues are found with this particular species, supplementing could be indicated bearing in mind some of the potential effects [2] noted already on this bacterium might already show indication in some cases of autism (see here). One might also see a way to look at this and other bacteria in conjunction with levels of oxytocin and possibly other important compounds too as part of that gut-brain axis. Given also that the Buffington study was a study of offspring of obese mice in terms of their sociability, does this also mean that kids born to overweight or obese mums are less likely to have age-appropriate social skills outside of any talk of autism?

There is still a research journey to be travelled in this area of investigation and, I might add, potentially linking various areas together including the idea that not all fats in a high-fat diet are necessarily the one and the same (see here)...

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[1] Buffington SA. et al. Microbial Reconstitution Reverses Maternal Diet Induced Social and Synaptic Deficits in Offspring. Cell.2016; 165: 1762-1775.

[2] Coccolrullo P. et al. Lactobacillus reuteri (DSM 17938) in Infants with Functional Chronic Constipation: A Double-Blind, Randomized, Placebo-Controlled Study. J Peds. 2010; 157: 598-602.

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Buffington, S., Di Prisco, G., Auchtung, T., Ajami, N., Petrosino, J., & Costa-Mattioli, M. (2016). Microbial Reconstitution Reverses Maternal Diet-Induced Social and Synaptic Deficits in Offspring Cell, 165 (7), 1762-1775 DOI: 10.1016/j.cell.2016.06.001

The 'anti-neuroinflammatory activity' of oxytocin

Whilst the package inserts of the various drugs that modern medicine has at its disposal provides important information on potential mode of action, there is a growing realisation that drugs generally have quite a few more molecular targets than are perhaps listed. Take for example the quite commonly used (in some parts of the world anyway) compound called melatonin  that in some instances can provide almost miraculous relief when it comes to sleeping issues under certain circumstances. A derivative of the amino acid tryptophan, melatonin might however be quite the molecular handy-person when it comes to its biological targets including its actions on something called leaky gut for example...

The paper by Lin Yuan and colleagues [1] similarly suggests that everyone's favourite 'cuddle hormone' (oxytocin) might also have a wider range of biological effects than has hitherto been fully appreciated.  Drawing on cell line results and intra-nasal administration of oxytocin (OT) to [artificially] immune-stimulated mice, authors reported that "OT possesses anti-neuroinflammatory activity and might serve as a potential therapeutic agent for treating neuroinflammatory diseases."

One of the primary analytical targets of the Yuan study were microglia, those 'constant gardeners' according to one description, and how administration of OT might have some interesting effects on the activation of microglia under certain circumstances. "BV-2 cells and primary microglia were pre-treated with OT (0.1, 1, and 10 μM) for 2 h followed by LPS [lipopolysaccharides] treatment" we are told, and microglia activation and "pro-inflammatory mediators" subsequently monitored. The results tallied with those 'anti-neuroinflammatory' sentiments previously expressed as authors report on various possible reasons for such an effect: "OT suppressed the expression of TNF-α, IL-1β, COX-2, and iNOS at the mRNA and proteins levels and reduced the elevation of [Ca2+]i in LPS-stimulated microglia cells." If that wasn't enough, researchers also looked at what happened following OT pre-treatment when a certain strain of mouse was 'immune stimulated' again in terms of microglia activation and those pro-inflammatory mediators. We are similarly told that: "pre-treatment with OT showed marked attenuation of microglial activation and pro-inflammatory factor levels." So we have something of a match in the lab and in an animal model.

These are interesting results. Yet again, one has to be a little cautious about the use of mouse models or indeed, cell lines (humans are so much more than a group of cells in a petri dish) and further, independent investigations are indicated. But: "These data suggested that OT would be a potential therapeutic agent for alleviating neuroinflammatory processes in neurodegenerative diseases."

I was inclined to talk about the Yuan paper because of the various 'connections' that have been made between oxytocin and autism (see here). With a growing interest in the oxytocin-autism connection in the peer-reviewed literature, this nonapeptide (9 amino acids long) has attracted quite a few researchers to its cause [2] as a function of the idea that: "Oxytocin increases the salience of social stimuli and promotes parental nurturing and social bonds" [3]. As per my interpretation of the current state of the oxytocin-autism research base, there are some interesting results available but once again, universal 'effects' are nowhere to be seen - Autisms, people. Autisms. The Yuan and other results focusing on the 'anti-neuroinflammatory' activity of oxytocin perhaps add another dimension to the possible hows and whys of efficacy when it comes to a label like autism. That also a growing number of people are coming around to the idea that neuroinflammation might be a facet of 'some' autism (see here) and including some mention of microglia (see here) offers an additional correlate to add into the future research mix. Could those with autism who have more prominent signs of neuroinflammatory issues potentially be 'best responders' to oxytocin for example? I did also wonder whether the idea that inflammation or inflammatory issues might feature in complex behaviours like social cognitive processing (see here) could provide another explanation for some of the reported results observed following use of oxytocin in [some] autism?

Much more research is indicated but again the message is... don't be too dogmatic when it comes to pharmacological targets and actions of medicines indicated for conditions such as autism. You might just end up being surprised...

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[1] Yuan L. et al. Oxytocin inhibits lipopolysaccharide-induced inflammation in microglial cells and attenuates microglial activation in lipopolysaccharide-treated mice. Journal of Neuroinflammation. 2016; 13:77.

[2] Okamoto Y. et al. The Potential of Nasal Oxytocin Administration for Remediation of Autism Spectrum Disorders. CNS Neurol Disord Drug Targets. 2016 Apr 13.

[3] Young LJ. & Barrett CE. Neuroscience. Can oxytocin treat autism? Science. 2015 Feb 20;347(6224):825-6.

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Yuan L, Liu S, Bai X, Gao Y, Liu G, Wang X, Liu D, Li T, Hao A, & Wang Z (2016). Oxytocin inhibits lipopolysaccharide-induced inflammation in microglial cells and attenuates microglial activation in lipopolysaccharide-treated mice. Journal of neuroinflammation, 13 (1) PMID: 27075756

MOCOS: a new candidate for autism research

I'll freely admit that until reading the paper by François Féron and colleagues [1] (open-access available here) I had never heard of MOCOS (MOlybdenum COfactor Sulfurase) before.

Described as "an enzyme of the purine metabolism that sulfurates the molybdenum cofactor, thus allowing the two downstream enzymes—xanthine dehydrogenase (XDH) and aldehyde oxidase (AOX1)—to be active", researchers reported that in nasal stem cells provided by a small group of adults diagnosed with an autism spectrum disorder (ASD), MOCOS was down-regulated compared with analyses of similar cells from asymptomatic controls. They concluded that differences related to MOCOS might be important: "likely to have an impact on neurodevelopment and neurotransmission, and may explain comorbid conditions, including gastrointestinal disorders."

I'm intrigued.

The Féron paper is open-access but a few details might be useful:

• Eleven participants diagnosed with autism (autism spectrum disorder, ASD) were included for study. Interestingly, DSM-5 diagnostic criteria were used to confirm the presence of ASD. Age and gender matched asymptomatic (for autism) controls were also used. As per the supplementary information included with the main article (see here), the authors characterised their participant group pretty well from various different angles.
• A nasal biopsy was performed on participants in order to extract "nasal olfactory stem cells" based on a previously published technique [2]. Again, it's new news to me that you can get stem cells from the nose but apparently the "olfactory epithelium is also a nervous tissue that produces new neurons every day to replace those that are damaged by pollution, bacterial of viral infections. This permanent neurogenesis is sustained by progenitors but also stem cells residing within both compartments of the mucosa, namely the neuroepithelium and the underlying lamina propria."
• Based on a "non-hypothesis-driven approach" Féron et al set about looking for "transcriptome anomalies" between the groups. Alongside other potentially important differences they stumbled across MOCOS in relation to their autism cohort and decided to look-see whether this might have some impact on cerebral functions using a classical worm model - Caenorhabditis elegans (C. elegans). A "genetic ablation of mocs-1 (the MOCOS ortholog)" engineered into the worm induced "an alteration of the response to oxidative stress and is responsible for abnormal neurotransmission phenotypes." Human cell studies confirmed this data.

Despite the small participant group, the MOCOS findings might carry some weight in view of some of the other 'dysregulated' genes that turned up with the ASD group in mind. So: "9 out of these 156 genes—ADAM23, CADM1, FOS, FOSB, JAG1, MEST, OXTR, SFRP1 and XIST—have been previously associated with ASD." You might note the mention of OXTR in that list, denoting the oxytocin receptor gene bearing in mind the cautious history in that area. That also pathway analysis of the genes differentially regulated in the autism group "identified developmental disorders and gastrointestinal diseases as two of the most represented categories associated with these genes" adds to the interest, bearing in mind the term 'over-represented' when it comes to bowel issues and autism (see here).

The suggestion that "MOCOS misexpression increases sensitivity to oxidative stress" is also an important part of the Féron findings. Oxidative stress and autism has quite a bit of peer-reviewed research history (see here for example) particularly in areas such as glutathione metabolism (see here) albeit not universally [3]. It's not beyond the realms of possibility that MOCOS may indeed be a contributory factor to such issues being present in some cases.

Further work is required in this area to corroborate the Féron data using larger participant numbers for example. With that in mind, I'll be keeping my eye open for more work on MOCOS and autism and whether it lives up to its 'new player' status...

Music: Weezer and Undone.

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[1] Féron F. et al. Olfactory stem cells reveal MOCOS as a new player in autism spectrum disorders. Mol Psychiatry. 2015 Aug 4.

[2] Girard SD. et al. Isolating nasal olfactory stem cells from rodents or humans. J Vis Exp. 2011 Aug 22;(54). pii: 2762.

[3] Durieux AM. et al. Cortical and subcortical glutathione levels in adults with autism spectrum disorder. Autism Res. 2015 Aug 20.

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Féron F, Gepner B, Lacassagne E, Stephan D, Mesnage B, Blanchard MP, Boulanger N, Tardif C, Devèze A, Rousseau S, Suzuki K, Izpisua Belmonte JC, Khrestchatisky M, Nivet E, & Erard-Garcia M (2015). Olfactory stem cells reveal MOCOS as a new player in autism spectrum disorders. Molecular psychiatry PMID: 26239292

Oxytocin moving on: ADHD and inattentiveness

Dare I mention the term 'cuddle hormone' when it comes to oxytocin?

Well, according to a recent news piece in Nature (see here), the 'cuddle hormone' days of oxytocin might well be numbered as science is starting to come to grips with just how complicated a role this hormone might have when it comes to biology and behaviour. Of course we've seen hints of this for quite a while now as autism research in particular comes to grips with the idea that oxytocin may not be the magic 'sociability' bullet that some people thought it might be (see here). That's not to say it might not have it's uses; just not for everyone and not necessarily just exclusively with [parts of] the autism spectrum in mind.

As if to prove a point, today I'm talking about the findings reported by Tsuyoshi Sasaki and colleagues [1] (open-access) and the observation that within a small participant group: "decreased levels of OXT [oxytocin] may play a role in the pathophysiology of patients with ADHD [attention-deficit hyperactivity disorder] and its inherent inattentiveness."

Measuring serum OXT levels in three groups - "drug naive ADHD (n=23), medicated ADHD (n=13), and age- and sex- matched, neurotypical controls (n=22)" - researchers reported that compared with asymptomatic controls, those with a diagnosis of ADHD presented with a significantly lower level as a group. Taking into account the variable of intervention for ADHD (pharmacotherapeutic intervention that is) also seemed to have effects on measured levels of OXT: "serum levels of OXT were significantly higher in medicated ADHD patients than in drug naïve counterparts."

To complete their study researchers also looked at the possibility of any correlation between levels of serum OXT and behavioural measures with ADHD in mind. They reported something of a possible relationship (negative correlation) between severity symptom scores globally on the ADHD-Rating Scale IV Japanese parents' version (ADHD-RS) (a favourite instrument of mine) and those specific to inattention sub-scores as a function of serum OXT. And with that comes the required call for further research in this area on the basis of their small participant size.

The authors appear to be a little incorrect in detailing their study as: "the first report demonstrating decreased serum levels of oxytocin in ADHD patients." Taurines and colleagues [2] had previously reported that: "Patients with ADHD differed from healthy control children by significantly decreased OT [oxytocin] concentrations." Most of the other research interest in OXT and ADHD seems to have been rooted in the idea that oxytocin as a "medical augmentation of labor" does not seemed to be linked to the later onset of offspring ADHD [3].

Back to the Sasaki study, and the authors try to make some sense of why they got the results that they did. First comes the idea that OXT might play a role in "the human limbic system, including the amygdala" complete with evidence of limbic system involvement potentially linked to ADHD and ADHD-type behaviours. Whilst interesting, I personally am a little sceptical about such a simplistic link. That researchers only looked at OXT levels on one day and during childhood tells us little about any previous levels of OXT during birth or infancy and how they may or may not have affected brain architecture. The fact also that no brain imaging was used as part of the current study means few conclusions can be drawn on this hypothesis at this time.

Next up is some discussion about OXT levels being linked to a variety of other conditions, some of which might overlap with ADHD. Of course this leads us back to autism / autism spectrum and the idea that ADHD and autism appearing comorbid is no stranger to clinical research and practice (see here). Just think ESSENCE. I do think that Sasaki et al are 'on the money' when they suggest "using larger sample sizes of ASD [autism spectrum disorder] cohorts" alongside the ADHD slant as the next step in the evolution of this research area. This might tell us a little more about the nature of any OXT overlap and indeed, which combination of autistic and ADHD traits might further guide OXT research. Needless to say that oxytocin is getting a whole lot more complicated and likely to see even further interest under the wide, wide remit of psychiatry [4]...

Music: Gnarls Barkley - Crazy.

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[1] Sasaki T. et al. Decreased levels of serum oxytocin in pediatric Patients with attention deficit / hyperactivity disorder. Psychiatry Research. 2015. June 15.

[2] Taurines R. et al. Oxytocin plasma concentrations in children and adolescents with autism spectrum disorder: correlation with autistic symptomatology. Atten Defic Hyperact Disord. 2014 Sep;6(3):231-9.

[3] Henriksen L. et al. Medical augmentation of labor and the risk of ADHD in offspring: a population-based study. Pediatrics. 2015 Mar;135(3):e672-7.

[4] Rich ME. & Caldwell HK. A Role for Oxytocin in the Etiology and Treatment of Schizophrenia. Front Endocrinol (Lausanne). 2015 Jun 3;6:90.

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Sasaki, T., Hashimoto, K., Oda, Y., Ishima, T., Kurata, T., Takahashi, J., Kamata, Y., Kimura, H., Niitsu, T., Komatsu, H., Ishikawa, M., Hasegawa, T., Shiina, A., Hashimoto, T., Kanahara, N., Shiraishi, T., & Iyo, M. (2015). Decreased levels of serum oxytocin in pediatric Patients with attention deficit / hyperactivity disorder Psychiatry Research DOI: 10.1016/j.psychres.2015.05.029

Oxytocin and autism: the hype?

Consider some excerpts from two recent papers looking at oxytocin (OXT) - the "love hormone"(!) - and the autism spectrum disorders (ASDs)...

“It’s not the years, honey. It’s the mileage”

"These findings indicate that dysregulated OXT biology is not uniquely associated with ASD social phenotypes as widely theorized, but instead variation in OXT biology contributes to important individual differences in human social functioning, including the severe social impairments which characterize ASD" according to Karen Parker and colleagues [1]. Some media accompanying this paper can be found here.

and

"Participants who received oxytocin showed no benefit following treatment on primary or secondary outcomes" according to the findings reported by Adam Guastella and colleagues [2].

For those who have followed the autism research scene over the years, you'll know that discussions about some connection between the neuropeptide oxytocin and autism have figured quite prominently. Indeed, I've covered OXT and autism before on this blog (see here). Media headlines like the one from the BBC suggesting that the "Love hormone 'helps autistic brain'" have been quite a regular feature, building up OXT to almost Saintly proportions. Unfortunately, as has often been the case with autism (sorry, the autisms) the science has not exactly followed the hype. Take for example the paper by Dadds and colleagues [3] who, prior to Guastella et al, reported that: "Compared to placebo, intranasal oxytocin did not significantly improve emotion recognition, social interaction skills, or general behavioral adjustment in male youths with autism spectrum disorders".

I'm not saying that all the research on OXT and autism is bunk because that's obviously not true [4]. As per the meta-analysis by Preti and colleagues [5] there may, for example, be some merit in continuing looking at where and when OXT use might be indicated including that related to important comorbidity [6]. The route of administration - intranasal (via the nose) - is for me, also a really interesting drug delivery method which may be applicable to many, many different medicines indicated for autism or peripheral symptoms/conditions.

But what the Parker and Guastella studies do tell us, is that once again, grand over-arching theories of autism seemingly serve no-one well. The study by Bedford and colleagues [7] perhaps said it best with their data arguing: "against cognitive theories of ASD which propose that a single underlying factor has cascading effects across early development leading to an ASD outcome". Replace cognitive theories with biological ones and science seems to be getting a little closer to what looks like the real nature of the autisms, heterogeneity, comorbidity and all... Oh, and then there is some interesting data on how oxytocin might be affecting the "second brain" (gastrointestinal function) as well as the grey-pinkish matter [8]. Move over melatonin (see here)?

Music to close and I'm happy to be stuck with you... (stick with the video, the music does eventually kick in).

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[1] Parker KJ. et al. Plasma oxytocin concentrations and OXTR polymorphisms predict social impairments in children with and without autism spectrum disorder. PNAS. 2014. August 4.

[2] Guastella AJ. et al. The effects of a course of intranasal oxytocin on social behaviors in youth diagnosed with autism spectrum disorders: a randomized controlled trial. J Child Psychol Psychiatry. 2014 August 2.

[3] Dadds MR. et al. Nasal oxytocin for social deficits in childhood autism: a randomized controlled trial. J Autism Dev Disord. 2014 Mar;44(3):521-31.

[4] LoParo D. & Waldman ID. The oxytocin receptor gene (OXTR) is associated with autism spectrum disorder: a meta-analysis. Mol Psychiatry. 2014 August 5.

[5] Preti A. et al. Oxytocin and autism: a systematic review of randomized controlled trials. J Child Adolesc Psychopharmacol. 2014 Mar;24(2):54-68.

[6] Hall SS. et al. Effects of intranasal oxytocin on social anxiety in males with fragile X syndrome. Psychoneuroendocrinology. 2012 Apr;37(4):509-18.

[7] Bedford R. et al. Additive effects of social and non-social attention during infancy relate to later autism spectrum disorder. Dev Sci. 2014 Jul;17(4):612-20.

[8] Welch MG. et al. Oxytocin regulates gastrointestinal motility, inflammation, macromolecular permeability, and mucosal maintenance in mice. Am J Physiol Gastrointest Liver Physiol. 2014 Aug 21. pii: ajpgi.00176.2014.

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Parker, K., Garner, J., Libove, R., Hyde, S., Hornbeak, K., Carson, D., Liao, C., Phillips, J., Hallmayer, J., & Hardan, A. (2014). Plasma oxytocin concentrations and OXTR polymorphisms predict social impairments in children with and without autism spectrum disorder Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1402236111


Guastella AJ, Gray KM, Rinehart NJ, Alvares GA, Tonge BJ, Hickie IB, Keating CM, Cacciotti-Saija C, & Einfeld SL (2014). The effects of a course of intranasal oxytocin on social behaviors in youth diagnosed with autism spectrum disorders: a randomized controlled trial. Journal of child psychology and psychiatry, and allied disciplines PMID: 25087908

More bumetanide and autism discussion

For those with their ear to the autism research ground, the paper by Roman Tyzio and colleagues [1] must have sounded like a freight train coming given the volume of headlines that have been generated from this research (see here for example). Circling around the neurotransmitter, GABA (as in GABA dabba doo!), their findings based on two mouse models of autism, or rather autism and Fragile X syndrome - including the very interesting prenatal valproate (VPA) exposure model - suggested "hippocampal neurons in these models have elevated intracellular chloride levels, increased excitatory GABA, enhanced glutamatergic activity, and elevated gamma oscillations".

If that all that sounds like a different language to you, it basically boiled down to GABA doing the opposite of what it is normally supposed to do i.e. primarily act as an inhibitory neurotransmitter, potentially as a result of issues with chloride levels. The fact that the 'cuddle me' hormone, oxytocin is also a suggested trigger to facilitate that excitatory-to-inhibitory transition for GABA [2] in the early days adds to the intrigue. On it's own, this finding would probably have not generated as many media headlines as it did. But when combined with the suggestion that supplementation to mother rats with the diuretic drug bumetanide just before giving birth might help make that transition for GABA to fulfil it's inhibitory destiny ("it is your destiny") in offspring the research starts to take on a slightly different perspective. The Nature news write-up of the paper provides some additional reading on this issue (see here).

I've talked about bumetanide before on this blog (see here) as a consequence of the previous Lemonnier trial [3] which itself generated a fair few headlines at the time of publication. Since then, I've noted the odd mention on the drug in connection to the autism spectrum as per the case report from Grandgeorge and colleagues [4] and another paper from Lemonnier and colleagues [5] with a case of Fragile X syndrome in mind. The Grandgeorge results in particular, are worthy of inspection not least because of the focus on sensory issues and the link I make back to the very intense, intense world theory of autism [6] which has its roots in the VPA rodent model similar to the one used to test bumetanide in the Tyzio paper. I know we should be cautious of sweeping generalised models when it comes to autism (as per some chatter about the model) but lets not throw baby and bathwater out just yet. The scientific puritans out there might also be shaking their heads at the thought of case reports being mentioned here, but just remember the old adage about meeting one person with autism and all that.

There is obviously a degree of step-back caution to take from the Tyzio results insofar as rats being rats not humans. I believe the accompanying editorial from Zimmerman & Connors also raises a few potential issues which need to be resolved; not least how one ascertains who [humans] might be at risk for this process occurring and therefore when bumetanide might be indicated. Bear in mind too, that there are growing moves to look at reducing things like prenatal valproate exposure on the back of some regulatory statements recently being made (see here).

But I have to conclude that I do find the recent Tyzio report and the previous Lemonnier trial very interesting and look forward to seeing more research on this topic including safety studies, long-term follow-up and perhaps more data on who might be more likely to benefit from this research.

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[1] Tyzio R. et al. Oxytocin-mediated GABA inhibition during delivery attenuates autism pathogenesis in rodent offspring. Science. 2014 Feb 7;343(6171):675-9.

[2] Tyzio R. et al. Maternal oxytocin triggers a transient inhibitory switch in GABA signaling in the fetal brain during delivery. Science. 2006 Dec 15;314(5806):1788-92.

[3] Lemonnier E. et al. A randomised controlled trial of bumetanide in the treatment of autism in children. Transl Psychiatry. 2012 Dec 11;2:e202. doi: 10.1038/tp.2012.124.

[4] Grandgeorge M. et al. The effect of bumetanide treatment on the sensory behaviours of a young girl with Asperger syndrome. BMJ Case Rep. 2014 Jan 31;2014.

[5] Lemonnier E. et al. Treating Fragile X syndrome with the diuretic bumetanide: a case report. Acta Paediatr. 2013 Jun;102(6):e288-90. doi: 10.1111/apa.12235.

[6] Markram H. et al. The intense world syndrome--an alternative hypothesis for autism. Front Neurosci. 2007 Oct 15;1(1):77-96.

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Tyzio R, Nardou R, Ferrari DC, Tsintsadze T, Shahrokhi A, Eftekhari S, Khalilov I, Tsintsadze V, Brouchoud C, Chazal G, Lemonnier E, Lozovaya N, Burnashev N, & Ben-Ari Y (2014). Oxytocin-mediated GABA inhibition during delivery attenuates autism pathogenesis in rodent offspring. Science (New York, N.Y.), 343 (6171), 675-9 PMID: 24503856

Induced labour, maternal thyroid hormone and autism

The BBC TV program 'The Nine Months That Made You' was a particularly interesting eye-opener for me. Not only did it introduce the work of David Barker (see this post) and his very thoughtful hypothesis but also stressed how environmental factors during those early months (and perhaps even before we were glints in our parents' eyes) might have potentially far-reaching effects on how we live our lives.

With the early months in mind, I'm introducing two pieces of research which have been (fairly) recently doin' the rounds. The first is the paper by Simon Gregory and colleagues* who suggested that there may be a correlation between the medical induction of labour and an elevated risk of offspring autism. You can also see some media coverage of this paper here and some rather more critical discussion here. The second paper is by Gustavo Román and colleagues** who again with the correlation machine in full working order suggested that the risk of offspring autism was greater for those mothers who were deficient in thyroid hormone. Again, some coverage can be viewed here.

I'm not on this occasion going to focus too much on the Gregory paper because others have done a far better job than I could. I was interested in two points raised in the article though: (a) that males seemed to show more of an 'association' between such birthing interventions and subsequent risk - think fragile male for example, and (b) that we are presented with a slightly different viewpoint about the potential value of the 'cuddle hormone', oxytocin. Indeed this potentially more ominous side to oxytocin is something that has been discussed previously in the scientific literature (see here).

The Román paper on maternal hypothyroxinemia - low levels of thyroid functioning - and offspring autism risk is an interesting one. A couple of years back I wrote a post on autism and the thyroid (see here). At that time (2011) there was only a limited published research base on how the thyroid hormones and its functions 'might' be linked to autism, but that's not to say it hadn't been mentioned (see this paper***). The difference with the Román paper was the focus on maternal thyroid function in line with other reports that hypothyroxinemia in pregnancy might not be particularly desirable for later offspring outcomes (see this paper**** open-access for example).

Based on quite a large initial sample of over 5000 women taking part in the Generation R Study in the Netherlands (which itself has produced some interesting work), Román et al. looked at various aspects of thyroid function during early-middle pregnancy. They specifically focused on severe maternal hypothyroxinemia. A number of years later, mums (and dads) then completed various measures of behavioural functioning for offspring from which authors derived "a probable autistic child". The results suggested that where severe maternal hypothyroxinemia (n=136) was present, the odds ratio for having a 'probable' child with autism was significantly elevated.

I probably don't need to point out why I have highlighted the word 'probable' in the above paragraph. The fact that the authors relied on parental report of one of the sub scales of the Child Behavior Checklist "and/or" the Social Responsiveness Scale could be construed as at odds with the title of the behaviour which specifically talks about "increased autism risk" over and above what they were actually looking at: "autistic symptoms". You might think I am just nit-picking about this but certainly I wouldn't want anyone to think that diagnosing an autism spectrum conditions is as easy as just filling out a short questionnaire. Screening and part of the assessment procedure... yes, diagnosis... no.

That all being said I remain interested in the findings and wisely how the authors stress that their findings "cannot establish causality" That and the fact that Román has previously published on some interesting ideas to account for thyroid issues in relation to autism***** means that science has a few more avenues to look at to potentially account for their findings (see here too).

Music maestro please. How about Blur with Girls and Boys?

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* Gregory SG. et al. Association of Autism With Induced or Augmented Childbirth in North Carolina Birth Record (1990-1998) and Education Research (1997-2007) Databases. JAMA Pediatr. 2013 Aug 12. doi: 10.1001/jamapediatrics.2013.2904.

** Román GC. et al. Association of gestational maternal hypothyroxinemia and increased autism risk. Ann Neurol. 2013 Aug 13. doi: 10.1002/ana.23976.

*** Hoshiko S. et al. Are thyroid hormone concentrations at birth associated with subsequent autism diagnosis? Autism Res. 2011 Dec;4(6):456-63. doi: 10.1002/aur.219.

**** Negro R. et al. Hypothyoxinemia and pregnancy. Endocr Pract. 2011 May-Jun; 17(3): 422–429.

***** Román GC. Autism: transient in utero hypothyroxinemia related to maternal flavonoid ingestion during pregnancy and to other environmental antithyroid agents. J Neurol Sci. 2007 Nov 15;262(1-2):15-26.

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Gregory SG, Anthopolos R, Osgood CE, Grotegut CA, & Miranda ML (2013). Association of Autism With Induced or Augmented Childbirth in North Carolina Birth Record (1990-1998) and Education Research (1997-2007) Databases. JAMA pediatrics PMID: 23938610




Román GC, Ghassabian A, Bongers-Schokking JJ, Jaddoe VW, Hofman A, de Rijke YB, Verhulst FC, & Tiemeier H (2013). Association of gestational maternal hypothyroxinemia and increased autism risk. Annals of neurology PMID: 23943579

Cuddle me oxytocin

Without wishing to sound like I have had one beer to many, if this blog was an ice-cream I would generally liken it to a neapolitan. The reason being that I'd like to think that rather than just being 'plain' and providing only one flavour of interest, I try and make it more of a 'selection' ice-cream (bearing in mind that the chocolate portion always seems to go first). In my quest to provide the 'near-perfect neapolitan', I offer up this post on the hormone oxytocin.

Oxytocin (OT) has, whether fortunately or unfortunately, picked up the label of being the 'cuddle hormone' in certain circles given its connection to pair-bonding between mother and baby during that most sensitive of times, early infancy (very early infancy) and its empathetic undertones. It is quite a small peptide synthesised in the hypothalamus. Outside of uterine contraction and involvement with lactation, OT has found some interest in relation to quite a few different things. The more 'saucy' areas of OT are still the subject of some debate and given that this is 'not that type of blog' I will perhaps put such research to one side.

The attachment side of OT has meant that it has been looked at in relation to autism spectrum and related conditions given the focus (rightly or wrongly) on social interactive behaviours. Outside of the interest in possible genetic issues with oxytocin chemistry in autism, quite a lot of discussion has centred on the potential therapeutic properties of oxytocin administration for autism in light of lower plasma levels of OT being reported in some cases. The research is quite interesting: this study (randomised, double-blind, placebo-controlled) suggested the OT administration reduced repetitive behaviours. This study suggested that emotion recognition was improved following intranasal administration of OT. I like this study in particular, given its quite ingenious method of drug delivery - a nasal spray - a method which could no doubt be applied to lots of other pharmacotherapies used as part of symptom management, particularly those with a need to bypass the gastrointestinal route. OT is also showing some promising results for conditions such as schizophrenia.

There is perhaps another side to OT which also deserves some attention. A quite speculative article published in Medical Hypotheses theorised at a possible relationship between pitocin (OT) induction and autism. So far however the evidence for such an assertion is weak although there is some suggestion of similar correlations related to ADHD (an important co-morbidity to autism). It does look like oxytocin might have some role to play in some components of autism (in some cases). A quick search of ClinicalTrials.gov suggests that there is quite a lot of research on-going on autism and OT. The question is whether OT is the chocolate part of our neapolitan ice-cream or just the strawberry or vanilla sections? We wait to see.