Carnitine supplementation and autism: "side-effects and behavioral outcomes"

'Favourable outcomes' is a term mentioned in amongst the various findings reported by Robin Goin-Kochel and colleagues [1] following their examination of "dose compliance, attrition, and potential side effects of short-term, high-dose carnitine supplementation" in a small group of boys diagnosed with an autism spectrum disorder (ASD). Understanding that the Goin-Kochel study was primarily directed at looking at safety, on the basis of 'high-dose' carnitine supplementation, it appears that an elevation of plasma carnitine and related metabolites was not the only effect noted in their small cohort (N=10).

Tracking back slightly, carnitine is an important compound. Not quite an amino acid, carnitine plays an important role in energy production; as per use of the word 'mitochondria' and it's transporting duties of long-chain fatty acids to the cell powerhouse for energy conversion. You probably won't be surprised to hear that carnitine has a *connection* to some autism (see here and see here). Indeed, Goin-Kochel et al mention the findings reported by Patrician Celestino-Soper and colleagues [2] and their identification of a genetic issue that impacts on 'carnitine biosynthesis' in some people diagnosed with ASD. At least one of the authors on the Goin-Kochel paper has some pretty important knowledge about that finding of trimethyllysine hydroxylase epsilon (TMLHE) gene issues in the context of autism...

Alongside looking for reports of any side-effects from the use of carnitine - "oral suspension or tablets of levocarnitine in 3 divided doses, starting at 200 mg/kg/day and increasing to 400 mg/kg/day, with a maximum daily dose of 6 g" - various behavioural schedules were included in the study protocol. Some were objective measures of autism symptomatology; others were parent-report measures. The use of the Clinical Global Impression Scale (CGIS) also provided a helpful 'clinicians' overview' of before and after supplementation in this open-trial.

Results: a few side-effects coinciding with carnitine use were reported. These included: "heavy odor (4 parents), diarrhea (4 parents), and sporadic vomiting (1 parent)." Such reported side-effects meant that three children remained at the lower dose of carnitine over the experimental period (8 weeks).

Alongside, a few other 'favourable outcomes' were also reported: "calmer behavior (2 parents), more energy (2 parents), increased prosocial behaviors (4 parents), greater awareness (2 parents), better eye contact (2 parents), and improved language skills (2 parents)." These parental reports were accompanied by some 'changes' noted on the various schedules included in the study protocol, including those CGIS ratings. The authors used the study results produced by Geier and colleagues [3] as their comparator; highlighting how both studies had picked up "improvements in overall ASD symptoms... and some language ratings." Importantly too, Goin-Kochel et al talk about how none of their cohort were rated as "worse at post treatment."

Where next? More research please. Bigger participant numbers, more methodologically sound study designs and perhaps also, investigation of the potential pros-and-cons of carnitine supplementation over a longer period of time. By all means keep an eye on those side-effects and perhaps look to the biochemistry as to why such side-effects might appear; indeed look to the biochemistry for potential best-responders to this type of intervention too ("One child had documented TMLHE deficiency and 3 had low carnitine levels" in the Goin-Kochel cohort). But more study is definitely indicated...

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[1] Goin-Kochel RP. et al. Side Effects and Behavioral Outcomes Following High-Dose Carnitine Supplementation Among Young Males With Autism Spectrum Disorder: A Pilot Study. Global Pediatric Health. 2019; 6: 1-8.

[2] Celestino-Soper PB. et al. A common X-linked inborn error of carnitine biosynthesis may be a risk factor for nondysmorphic autism. Proc Natl Acad Sci U S A. 2012 May 22;109(21):7974-81.

[3] Geier DA. et al. A prospective double-blind, randomized clinical trial of levocarnitine to treat autism spectrum disorders. Med Sci Monit. 2011 Jun;17(6):PI15-23.

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Melatonin pathway dysregulation driving melatonin issues associated with autism?

The paper published by Anna Maruani and colleagues [1] provides the blogging fodder today and the observation that: "melatonin variations in ASD [autism spectrum disorder] could be mainly driven by melatonin pathway dysregulation."

Melatonin has been part-and-parcel of the autism research landscape for many, many years (see here). Most people with some knowledge of melatonin will probably know of its connection to the sleep-wake cycle and the reasoning behind the use of supplemental melatonin to [hopefully] improve sleep in some people and groups of people (see here). Indeed, for some of those diagnosed as being on the autism spectrum who present with often significant sleep-related problems (see here for example), the clinical use of melatonin has been nothing short of miraculous for some when it comes to improving several parameters of sleep [2]. But melatonin is also quite the molecular handyperson too (see here) outside of just the sleep-wake cycle...

As to the precise reason(s) why melatonin appears to be an issue for 'some autism', science so far has been pretty short on firm conclusions. The Maruani study set out to try and cast some further light on the hows-and-whys around melatonin, specifically looking at both measured levels of melatonin in plasma and also pineal gland volume (PGV), on the basis that the pineal gland produces melatonin. Researchers report estimated measurement of PGV "with magnetic resonance imaging (MRI) with a voxel-based volumetric measurement method" in "78 individuals with ASD, 90 unaffected relatives and 47 controls."

Their results were interesting: "We first found that both early morning melatonin level and PGV were lower in patients compared to controls." Those early morning melatonin levels - "collected between 8:30 and 10:30 a.m." - were measured using "a radioimmunoassay" method looking at plasma samples. As well as lower plasma melatonin being described in the autism group compared with the other groups, researchers also observed that: "Relatives displayed to a lesser extent a reduced level of melatonin compared to controls, but that did not reach significance z = 0.88, p = 0.38)." Potentially also interesting.

Further: "Analysis revealed that the volume of the pineal gland was lower in patients than in controls, and lower in relatives than in controls." Some additional statistical modelling led however to the conclusion that: "PGV acted as a modest contributor to the melatonin deficit observed in ASD." In other words, as per the title of this post "melatonin variations in ASD could be mainly driven by melatonin pathway dysregulation" over and above just the physical volume of the part of the brain charged with producing melatonin.

Mention of 'melatonin pathway dysregulation' in the Maruani results got me thinking about previous study results discussed on this blog (see here). The results from Pagan and colleagues [3] provided some pretty valuable insights into the biochemistry of melatonin and some of the 'in-betweener' compounds involved in it's formation. Specifically: "a disruption of the serotonin-NAS [N-acetylserotonin] -melatonin pathway in ASD." Add in other research (see here) talking about low levels of one of the metabolites of melatonin being noted in parents, and there's a case for looking further at the biochemistry of melatonin synthesis in relation to autism over and above just volumes of brain structures. Indeed, how about beginning with examinations of the starting material for melatonin - the amino acid tryptophan - and see where this might take us (see here and see here).

Oh, and it appears that the pineal gland is probably not the only place that melatonin is synthesised [4]. Perhaps further investigation in this area might also want to look at "the enterochromaffin (EC) cells throughout the gut" for example, and their potential role/effect with melatonin (and its precursors) and autism in mind...

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[1] Maruani A. et al. Morning Plasma Melatonin Differences in Autism: Beyond the Impact of Pineal Gland Volume. Front. Psychiatry. 2019. Feb 6.

[2] Maras A. et al. Long-Term Efficacy and Safety of Pediatric Prolonged-Release Melatonin for Insomnia in Children with Autism Spectrum Disorder. J Child Adolesc Psychopharmacol. 2018 Oct 11.

[3] Pagan C. et al. The serotonin-N-acetylserotonin-melatonin pathway as a biomarker for autism spectrum disorders. Transl Psychiatry. 2014 Nov 11;4:e479.

[4] Chen CQ. et al. Distribution, function and physiological role of melatonin in the lower gut. World J Gastroenterol. 2011;17(34):3888-98.

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"Starting this week, the first blood test for autism will be available to the public"

I have to say that of all the news outlets that I peruse now and again, the resource known as Disability Scoop is typically one of the best. They just always seem to be 'on the ball'. The headline titling this post - "Starting this week, the first blood test for autism will be available to the public" - comes from that resource and well, 'whoa' is a word that springs to mind.

The report details that a company called NeuroPointDX is "launching its NPDX AA test, a blood plasma test that screens for certain metabolic markers that the company has linked to autism spectrum disorder." Said test is based on some peer-reviewed science by Alan Smith [1] which concluded that the: "Identification and utilization of metabotypes of ASD [autism spectrum disorder] can lead to actionable metabolic tests that support early diagnosis and stratification for targeted therapeutic interventions." And before you ask, yes, I have covered the Smith paper before on this blog (see here).

Specific details of what is included in the NPDX AA test are, at the time of writing, not seemingly readily available. The 'AA' mention in the test name implies amino acids are going to be central to the analysis. Indeed, the Smith paper [1] talked about a few specific amino acids as potentially being important: "The combination of glutamine, glycine, and ornithine AADMs [Amino Acid Dysregulation Metabotypes] identified a dysregulation in AA/BCAA [branch chain amino acids] metabolism that is present in 16.7% of the CAMP [Children’s Autism Metabolome Project] ASD subjects and is detectable with a specificity of 96.3% and a PPV [positive predictive value] of 93.5%." What this translates into is that for at least one part of the very heterogeneous autism spectrum (maybe one or more of the autisms?), this test might be able to identify some metabolic issues that could be considered both diagnostic (for that particular 'type of autism') and also therapeutic, insofar as specific interventions aimed at specific amino acid 'issues' when identified (see here for one possible example).

Of course we've kinda been here before with the talk about a biological test for autism (see here for example) and history teaches us to be quite cautious when it comes to such discussions. We'll just have to see how well the NPDX AA test does 'in the field' before any further claims are made and even bigger 'shifts' in our knowledge of autism reported and accepted. But hey, at least give it a chance...

To close, your customary 'chat' from V to remember the date today...

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[1] Smith AM. et al. Amino acid dysregulation metabotypes: potential biomarkers for diagnosis and individualized treatment for subtypes of autism spectrum disorder. Biological Psychiatry. 2018. Sept 6

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The Children’s Autism Metabolome Project (CAMP) reports: "Amino acid dysregulation metabotypes"

The Children’s Autism Metabolome Project (CAMP), mentioned in the title of this post, is an initiative that aims to develop "a diagnostic blood test for autism." It's a project that grabbed my attention for a few reasons; not least the reliance on the science of metabolomics and the use of some pretty amazing technology headed under the term 'mass spectrometry' (see here for another example) to try and accomplish their goal.

The recent results published by Alan Smith and colleagues [1] provide some of the first results to come from the CAMP, and the observation that: "Identification and utilization of metabotypes of ASD [autism spectrum disorder] can lead to actionable metabolic tests that support early diagnosis and stratification for targeted therapeutic interventions." Just in case you were wondering: "A metabotype is a subpopulation defined by a common metabolic signature that can be differentiated from other members of the study population." Inevitable lay media headlines have also followed on from this work (see here).

The nuts and bolts? Well: "Dysregulation of AA metabolism was identified by comparing plasma metabolites from 516 children with ASD with those from 164 age-matched typically-developing (TYP) children recruited into CAMP." AA refers to amino acids, the biological building blocks of proteins, and how, yet again (see here and see here) these compounds might be quite important to at least some autism. Researchers were able to analyse blood (plasma) samples from the participants, pertinent to detecting various amino acids and looking at how levels might differ as a function of a diagnosis of autism. Interestingly and importantly, the words "Training and Test Sets" are also used in the Smith paper, denoting how: "A training set was used to identify metabotypes associated with ASD and a test set was used to evaluate the reproducibility of the metabotypes." Similar methodological processes have been noted in other autism metabolomic studies (see here). I'm not going to bore you with the technological details of the "Triple Quadrupole LC-MS/MS Method" used (I'm more inclined to q-ToF mass spec myself) but suffice to say that such technology did yield some pretty accurate and important results, and it wasn't all just about autism vs. not-autism either.

"A simple analysis of the mean concentrations of free plasma amines did not reveal meaningful differences between the ASD and TYP populations of children." This is an important point. It suggests that within this cohort, there was no significant difference in the biological profiles following a straight 'autism vs not-autism' analysis. Something perhaps not entirely unexpected given the significant heterogeneity under the behaviourally-defined label called autism. But... "scatterplots of amine levels indicated that there were subsets of children with ASD with amine levels at the extreme upper or lower end of the abundance distribution." Researchers then began zooming in on different sub-groups of their autistic cohort as part of their "Amino Acid Dysregulation Metabotype (AADM)" description. Such analysis revealed a few AADMs based on the ratios between various amino acids. Further: "Taken together, all AADMs identified an altered metabolic phenotype of imbalanced BCAA [branched chain amino acid] metabolism in 16.7% of CAMP ASD subjects with a specificity of 96.3% and PPV [positive predictive value] of 93.5%." This *could* be interpreted as suggesting that about 15% of kids with autism *could* be correctly identified via their amino acid profile.

Caveats? Well yes, a few. This was work, for example, based on a single blood sample from each participant, in effect, providing a snapshot of each person at a particular point in time. There are lots and lots of different variables that will affect our metabolome including health/illness, diet, exercise, any medicines taken, comorbidity, et al. It's not beyond the realms of possibility that any or all of those factors could have influenced the results both in the short- or longer-term. Indeed, I'd like to see a lot more research on the consistency of individual sample results across different time frames before any big claims about a diagnostic test for autism are made. Also, the term 'biomaker for autism': I again get the impression that there needs to be lots more 'cross-linking' discussion between groups committed to this research agenda (see here and see here for examples).

But I don't want to take anything away from this work and (hopefully) future publications to come the CAMP. And I do also want to mention a couple of other interesting snippets of information garnered from the current study. So, in one of the write-ups of the study, one of the authors who is not stranger to the concept of 'biomarkers for autism' (see here) discusses: "Amaral points to phenylketonuria (PKU) as a possible template. PKU is a rare disease in which the amino acid phenylalanine builds up, causing brain damage. However, relatively small dietary adjustments can make a big difference." PKU as a template for autism? I think I've heard that somewhere before (see here). And that's also to acknowledge that PKU and autism can very much exist together (see here) in the context that various inborn errors of metabolism seem to be able to produce autistic signs and symptoms (see here). And some of them are very treatable...

Also alongside, I must quickly mention about those branched-chain amino acids (BCAAs) highlighted by Smith et al. How, in the context of other previous important research talking for example, about a 'new form of autism found' (see here), there are lots and lots of research (and clinical) possibilities to come from the analysis of these types of amino acids in the context of autism (see here). And yes, this includes intervention...

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[1] Smith AM. et al. Amino acid dysregulation metabotypes: potential biomarkers for diagnosis and individualized treatment for subtypes of autism spectrum disorder. Biological Psychiatry. 2018. Sept 6.

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On postpartum paracetamol metabolites and risk of offspring ADHD: details matter

The findings reported by Yuelong Ji and colleagues [1] provide the blogging fodder today, as once again the topic of acetaminophen (a.k.a paracetamol) use during pregnancy and offspring risk of attention deficit hyperactivity disorder (ADHD) is in the spotlight. I say 'once again' because this topic has cropped up time and time again on this blog (see here for example).

On this research occasion, the starting point was the Boston Birth Cohort (a cohort that has been mentioned before) and specifically, an analysis of "maternal plasma acetaminophen metabolites levels measured within a few days after delivery and ADHD diagnosis in the offspring" as a measure of paracetamol exposure. The metabolites in question were "unchanged acetaminophen, acetaminophen glucuronide, and 3-(N-Acetyl-l-cystein-S-yl) acetaminophen." All were measured in blood plasma using one of the gold-standard chemical analytical techniques: mass spectrometry. A diagnosis of ADHD was extracted from medical records on the basis of ICD-9 and/or ICD-10 definitions.

Results: taking into account other potential confounding variables, authors reported finding "a significant positive association between maternal blood acetaminophen metabolite levels measured within 1–3 days postpartum and ADHD diagnosis in offspring." It's perhaps however important to understand how such a finding was arrived at, bearing in mind that ADHD was not the only diagnostic fruit examined in the Ji study. So: "The main exposures analyzed in this study were maternal acetaminophen metabolite levels, which were inverse normal transformed to approximate the normal distribution." What this means is that rather than reporting the specific levels of each paracetamol metabolites across different diagnoses and a 'neurotypical group' ("Children without any diagnosis of ASD [autism spectrum disorder], ADHD, developmental delays, or intellectual disabilities were classified as neurotypical (NT)"), authors chose to covert the raw values into groupings. Groupings were based around "no detection, below median, above median of detected values." I'm not altogether sure that this is the best way to report results; certainly I would have liked to have seen the raw values for each metabolite according to group as a comparator; but that's just my research preference. Researchers mention that they did not see any association between paracetamol metabolites and any other diagnostic label, and also stressed how the association remained when other potentially confounding variables were taken into account. And when it comes to ADHD, there are a few (see here for example).

How much weight can we give these results? Well, this is probably the first time that someone has looked at actual paracetamol metabolites in mums rather than just relying on maternal or doctor records of paracetamol usage during pregnancy, and that's a good thing. Authors also mention that their study was "further strengthened by the diagnosis of ADHD by both general pediatricians and developmental specialists." Add in the prospective design of the study, and you have some potentially important evidence for a *relationship* between paracetamol use and subsequent offspring development.

But... "this study only included a one-time measurement of maternal acetaminophen metabolite levels within 1–3 days postpartum." The authors rightly acknowledge that paracetamol is pretty quickly metabolised in the body so, at best, their study really only looked at recent paracetamol use immediately during or after birth. Maybe further study of archived samples during pregnancy (at multiple points during pregnancy) would provide some further information? And comments from the authors like "women with detectable levels of acetaminophen biomarkers are likely to be more regular users" really don't have any place in a scientific paper without supporting evidence. Particularly when pain relief is going to be pretty important when it comes to the process of childbirth.

Also: "our metabolite measurement method did not include acetaminophen sulfate, which accounts for 30–44% of the total metabolites of acetaminophen under the normal dosage." I don't want to go into the nitty-gritty of paracetamol metabolism, but just going back to the research looking at sulphation (sulfation) in the context of autism (see here), it would have been useful to examine both paracetamol sulphate and paracetamol glucuronide at the same time. Certainly it would have provided a more complete picture of typical paracetamol metabolism.

Don't get me wrong, I am interested in the Ji findings and their addition to the literature on paracetamol use and offspring outcomes. This still remains an important area of investigation. I'm not however completely convinced that the evidence presented by Ji and colleagues counts as particularly strong evidence despite the important measurement of paracetamol metabolites in this context...

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[1] Ji Y. et al. Maternal Biomarkers of Acetaminophen Use and Offspring Attention Deficit Hyperactivity Disorder. Brain Sci. 2018 Jul 3;8(7). pii: E127.

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Behind the headline: "Autism: Scientists take 'first steps' towards biological test"

Monday 19th February 2018. I opened my computer up early in the morning and lo and behold, headlines about autism appeared, as exemplified by the BBC article titling this post: "Autism: Scientists take 'first steps' towards biological test." A cold shudder ran down my body as memories of previous 'Super-parenting' improves children's autism and similar headlines sprung to mind and with it, the question of whether big claims were being made...

The paper behind the headlines this time around was from Attia Anwar and colleagues [1] (open-access) and I have to say at first sight I was really rather interested in the specific topic under investigation. Namely: "to explore the diagnostic utility of proteotoxic biomarkers in plasma and urine, plasma protein glycation, oxidation, and nitration adducts, and related glycated, oxidized, and nitrated amino acids (free adducts), for the clinical diagnosis of ASD [autism spectrum disorder]." Interested because the words 'amino acids' (an area of interest to this blog) were mentioned and also that their description of using "stable isotopic dilution analysis liquid chromatography-tandem mass spectrometry" plays to the analytical chemistry nerd that I've seemingly become down the years.

So, bearing in mind the Anwar paper is open-access, what were the hows-and-whys of this 'first steps' research? Well, the initial premise was a sensible one as words like '3-nitrotyrosine (3-NT)' are mentioned following other research noting this compound with some autism in mind (see here). It all ties into the process of oxidative stress and neuroinflammation that are becoming more readily accepted to be part-and-parcel of at least some autism (see here and see here). Researchers set out to see if they could detect some important compounds involved in the process of protein homeostasis (amino acids are the building blocks of protein) and whether, by using the process of machine learning on the derived data (see here for another example of this being applied to autism), the possibility of a diagnostic test for autism might be forthcoming from such work. Yes, this was another example of metabolomics being applied to autism research (see here and see here) and seems to continue a research journey from members of this authorship group [2].

Urine and plasma samples were the chosen analytical media, as authors report on the recruitment of 38 children diagnosed with an ASD and 31 not-autism controls. Yet again, the words 'healthy controls' are used to denote not-autism; something that we really shouldn't be seeing in this day and age. I'd also, by the way, say the same things about the term 'neurotypical' too (see here). The autism group did seem to have quite an extensive diagnostic work-up as both ADOS and CARS scores are presented. Spot blood and urine samples were provided by all and metabolomic analysis was begun...

Results: bearing in mind the significant complexity of both urine and plasma samples when it comes to the presence of small molecules and metabolites, the use of that mass spec method made short work of detecting the glycation markers indicated for study. I note also authors also provide some results on various amino acids in both urine and plasma that is, I think, rather important.

The first thing that struck me was the authors use of a compound called creatinine to correct for sample strength and dilution. I'd like to think I know a thing or two about creatinine (urinary) in relation to some autism on the back of a bit of published research a decade or so back [3]. Our conclusion then and also in some other independent work since (see here) is that caution is required when using creatinine as a corrector with autism in mind...

Having said that, a few findings are noteworthy: "we identified changes in plasma protein AGE [advanced glycation endproducts] and oxidation adducts, increased CML [Nε-carboxymethyl-lysine], CMA [Nω-carboxymethylarginine], and DT [dityrosine] and decreased 3DG-H [3-deoxyglucosone] in ASD." I'm not all too familiar with all of those compounds listed but going back to my observation on oxidative stress being something pertinent to some autism [4], I think there are some important connections to be seen. I note also that at least one of the findings - increased DT residue content of plasma proteins - might also provide a role for those trillions of wee beasties that call us home, the gut microbiota. Mention of the gastrointestinal (GI) tract in the context of autism is likely not to sit well with some people, despite multiple evidence of involvement for some in both a functional sense (see here) and also at a more biological level (see here).

Then to the headline maker: "Algorithms to discriminate between ASD and healthy controls gave strong diagnostic performance with features: plasma protein AGEs—CML, CMA—and 3-deoxyglucosone-derived hydroimidazolone, and oxidative damage marker, DT. The sensitivity, specificity, and receiver operating characteristic area-under-the-curve were 92%, 84%, and 0.94, respectively." Those sensitivity and specificity stats aren't bad at all. They are certainly on a par with other 'classification' attempts with autism in mind, such as when cortisol and a suite of cytokines got the same analytical treatment for example (see here). The trouble is that such stats are based on a relatively small sample size and indeed, children aged between 5-12 years old. Given that many children (but not all) are diagnosed quite a bit earlier than 5 years of age, one has to wonder how relevant any biological test might be at such a later age. One is left feeling that perhaps the discrimination analysis part of the Anwar paper should have perhaps been left until replication on an independent cohort with a larger sample size was carried out, and perhaps relying on more than one testing occasion.

I was also a little bit 'put out' that I couldn't find any 'limitation' discussions in the paper by Anwar et al. There was lots of chatter about how this, that and t'other might relate to biological processes pertinent to some autism but in the discussion section there was very little about what could be wrong with the results as they stand (e.g, small sample sizes). In the current age also when autism is more and more being talked about as NOT being a stand-alone diagnosis (see here) and indeed, probably is a more plural diagnosis ("the autisms"), it is always worthwhile mentioning how any obtained results might have to be framed in those contexts. Yes, authors did have exclusion criteria for study entrance: "Subjects with ascertained medical and neurological comorbidity were excluded, through a medical work up including electroencephalography (recorded during awake and sleep), cerebral magnetic resonance imaging, standard clinical and neurological examination, neurometabolic, and genetic investigations (including comparative genomic hybridization array, molecular assay for Fragile X and MECP2)" but autism pure might not be so typical in the real world [5].

Although some people have reacted quite strongly to the Anwar results, I do think this is quite a good study. No, as it stands, I don't think it can say that autism might be diagnosed on the basis of a urine and/or blood sample. Indeed, we've been here before (see here for example). But it does provide some welcome insight into some of the potential biology associated with at least some autism, and once again, champions the use of some really, really advanced metabolomic technology to provide potential systems biology insights into at least some autism...

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[1] Anwar A. et al. Advanced glycation endproducts, dityrosine and arginine transporter dysfunction in autism - a source of biomarkers for clinical diagnosis. Molecular Autism. 2018; 9: 3.

[2] Anwar A. et al. Quantitation of plasma thiamine, related metabolites and plasma protein oxidative damage markers in children with autism spectrum disorder and healthy controls. Free Radic Res. 2016 Nov;50(sup1):S85-S90.

[3] Whiteley P. et al. Spot urinary creatinine excretion in pervasive developmental disorders. Pediatr Int. 2006 Jun;48(3):292-7.

[4] Rossignol DA. & Frye RE. Evidence linking oxidative stress, mitochondrial dysfunction, and inflammation in the brain of individuals with autism. Front Physiol. 2014 Apr 22;5:150.

[5] Gillberg C. & Fernell E. Autism plus versus autism pure. J Autism Dev Disord. 2014 Dec;44(12):3274-6.

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"patients with CFS/ME do not exhibit insufficient concentrations of circulating total 25(OH)D"

The title heading this post comes from the findings reported by Kate Earl and colleagues [1] (open-access available here), where '25(OH)D' refers to calcifediol, a compound typically used to estimate how much vitamin D is present in the body and CFS/ME refers to Chronic Fatigue Syndrome / Myalgic Encephalomyelitis.

After assaying some 92 people with CFS/ME and an almost equal number of 'age-matched healthy controls' (HCs) for plasma total 25(OH)D and individual vitamin D metabolites - "25(OH)D2 and 25(OH)D3" - researchers concluded that vitamin D deficiency was not rife in their cohort. Indeed we are told that: "total 25(OH)D was significantly higher (p=0.001) in serum of patients with CFS/ME compared with HCs (60.2 and 47.3 nmol/L, respectively)." The authors were also able to report that vitamin D supplementation by the CFS/ME group seemed to be a primary reason for their findings.

There are a few important strengths to the Earl results that are worth mentioning. Not least that vitamin D metabolites were measured by mass spectrometric methods similar to other independent research occasions (see here for example). Mass spectrometry seems to have quite a few advantages over other methods of vitamin D analysis; now labelled as a gold-standard technique. Added to their use of a deuterated standard ("hexadeuterated (OH)D3") and one has some degree of confidence in the analytical results; albeit, as the authors acknowledge: "that only the main marker of vitamin D status, that is, 25(OH)D, was measured" and how "there is a need to assess all of the vitamin D metabolites" of which there are quite a few [2].

At first glance, the Earl findings seem pretty unremarkable. Supplementation with vitamin D, as everyone is being encouraged to do these days (see here), means higher levels of circulating vitamin D. I would be surprised if they didn't. This is also not the first time that vitamin D levels in relation to CFS/ME have been talked about in the peer-reviewed domain either (see here) albeit not always with the same results but again with that caveat about supplementation in mind.

Given however that a measure of fatigue - "the Chalder Fatigue Questionnaire" - was also included for all participants in the Earl study, and how nothing very much seemed to be present when looking at any connection between fatigue scores and vitamin D status, this provides a possible clue that vitamin D is probably not a big player specifically in relation to the presentation of fatigue in most cases of CFS/ME. Such a questionnaire does not rule out other potential associations (e.g. post-exertional malaise, PEM) nor that other, potential comorbidity appearing alongside CFS/ME might not have a stronger vitamin D link (see here for example). But for now, it adds to the literature (see here) casting doubt on any direct role for vitamin D in relation to CFS/ME.

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[1] Earl KE. et al. Vitamin D status in chronic fatigue syndrome/myalgic encephalomyelitis: a cohort study from the North-West of England. BMJ Open. 2017 Nov 8;7(11):e015296.

[2] Abu Kassim NS. et al. Simultaneous determination of 12 vitamin D compounds in human serum using online sample preparation and liquid chromatography-tandem mass spectrometry. J Chromatogr A. 2017 Dec 6. pii: S0021-9673(17)31772-7.

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S100B protein and autism continued

"Our findings showing an increase in peripheral concentrations of S100B and TNF-α provide limited support to the hypothesis about the roles of altered immune function and S100B in autism spectrum disorder (ASD)."

So said the findings reported by Selin Aktan Guloksuz and colleagues [1] (open-access available here) continuing some discussions a few years back on a possible role for S100B in relation to at least some autism (see here).

S100B - S100 calcium-binding protein B - is a compound involved in quite a few biological reactions not least "as a biomarker of global glial activity." Elevations of the S100B have been reported in relation to several states including that of [traumatic] brain injury. Outside of some research suggesting that elevations of S100B might also be a feature of diagnoses such as schizophrenia (see here), it has also been the topic of investigations with [some] autism in mind [2] too. The name of the game is elevations in S100B in relation to autism and more.

Based on analyses of fasting blood samples from "40 unmedicated children with autism" (where autism diagnoses were confirmed by study researchers) and 35 asymptomatic control children, researchers measured levels of plasma S100B alongside various markers of immune function (cytokines). Among the suite of cytokines examined, levels of "tumor necrosis factor alpha (TNF-α), interferon gamma, interleukin (IL)-1β, IL-4, IL-6, IL-10, and IL-17A" were included. The idea of using unmedicated children with autism stems from the suggestion that at least one medication used for some autism might have the ability to elevate S100B [3].

Results: as per the opening sentence to this post, levels of S100B and TNF-α were 'different' between the groups (both elevated) and this finding remained "after controlling for age, sex, and BMI [body mass index]." Researchers also reported some results looking at whether ASD symptom presentation might show any 'association' with S100B levels. On this topic they reported that: "Plasma S100B concentrations in children with severe ASD symptoms were higher than in children with mild-moderate ASD symptoms" but when again controlling for age, sex and BMI this association did not hold (significantly). As for the other cytokines outside of TNF-α... nothing came up as significant between the groups. This is interesting in light of recent work (see here) and even Guloksuz et al talk about future "prospective longitudinal studies investigating a broad set of immune markers, both in serum and CSF [cerebrospinal fluid], in large samples" and the pros- and cons of looking in CFS.

Where next for this area of investigation? Well, taking into account the link between S100B and brain injury and what that could mean for cognitive processes for example, I'd be minded to suggest that more study is needed looking at the effect of S100B levels in relation to cognition and autism. Take for example the study results from Chen and colleagues [4] who reported that "serum S100B level was an independent contributor to the global cognitive dysfunctions, particularly for the speed of processing, attention/vigilance, visual learning and reasoning/problem solving subscores" in their cohort of participants with schizophrenia. Might similar correlations be present alongside S100B elevations in relation to autism? I'd also be minded to suggest looking at a possible role for comorbidities potentially accompanying a diagnosis of autism as being important for S100B elevations in light of other research on depression for example [5]. Depression (various types) and autism is very much an important area of overlap (see here for example) and might actually offer at least one way to target elevations in S100B.

There is more to do on this topic.

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[1] Guloksuz SA. et al. Elevated plasma concentrations of S100 calcium-binding protein B and tumor necrosis factor alpha in children with autism spectrum disorders. Rev Bras Psiquiatr. 2017 Jan 12:0.

[2] Al-Ayadhi LY. & Mostafa GA. A lack of association between elevated serum levels of S100B protein and autoimmunity in autistic children. J Neuroinflammation. 2012 Mar 16;9:54.

[3] Quincozes-Santos A. et al. Effect of the atypical neuroleptic risperidone on morphology and S100B secretion in C6 astroglial lineage cells. Mol Cell Biochem. 2008 Jul;314(1-2):59-63.

[4] Chen S. et al. Cognitive dysfunction correlates with elevated serum S100B concentration in drug-free acutely relapsed patients with schizophrenia. Psychiatry Res. 2017 Jan;247:6-11.

[5] Rajewska-Rager A. & Pawlaczyk M. The role of S100B protein as a potential marker in affective disorders. Psychiatr Pol. 2016;50(4):849-857.

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Guloksuz SA, Abali O, Aktas Cetin E, Bilgic Gazioglu S, Deniz G, Yildirim A, Kawikova I, Guloksuz S, & Leckman JF (2017). Elevated plasma concentrations of S100 calcium-binding protein B and tumor necrosis factor alpha in children with autism spectrum disorders. Revista brasileira de psiquiatria (Sao Paulo, Brazil : 1999) PMID: 28099628

Fatty acid chemistry and autism

"Fatty acids in both serum and red blood cells were abnormal among this small group of Canadian children with autism compared to controls, underlining a need for larger age- and gender-matched investigations in this community."

Based on the analysis of fatty acid status in a small group of children with autism spectrum disorder (ASD) (n=11) compared with a small group of 'not-autism' control participants (n=15), the paper by Joan Jory [1] reports that there may be more to see in this important area. Specifically, the author reports on how lower levels of various important fatty acids (docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), arachidonic acid (AA)) were detected in both analysis of red blood cells and serum for the group of children diagnosed with autism compared to controls.

This is not the first time that such findings have been talked about with autism in mind (see here). That also Jory reported that the ratio between the omega-3 fatty acids and the omega-6 fatty acids was lower in the autism group is not also new news in light of some quite speculative discussions on how "disturbances in n-6/n-3 ratios may contribute to the emergence of ASDs" [2]. I might add that such speculative opinions require quite a lot more science before anyone makes any sweeping generalisations.

Appreciating that science has been a bit hit-and-miss when it comes to attempts to correct fatty acid issues with autism and behaviour in mind (see here), I'm of the opinion that if we take autism out of the equation, fatty acid deficiency/insufficiency when diagnosed should be managed. I say this on the same basis that important issues with other nutrients such as vitamin D when diagnosed should be acted upon irrespective of a diagnostic label of autism or anything else (see here).

That also there may be specific comorbidities and skills potentially affected by fatty acid issues (see here and see here respectively) with autism in mind is worth noting. Allied to the idea that specific parts of the autism spectrum may be more 'sensitive' to fatty acid intervention (see here) and we have recipe for quite a bit more investigation. Insofar as the notion from Jory that fatty acids might be part of a complex story involving "propionic acid production" and autism, well, I'm not adverse to this message in light of other preliminary research in this area (see here). I say that mindful of the fact that there may be many 'links' between fatty acids and autism [3] and one shouldn't necessarily get bogged down with just one potential association...

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[1] Jory J. Abnormal fatty acids in Canadian children with autism. Nutrition. 2015. Dec 2.

[2] van Elst K. et al. Food for thought: dietary changes in essential fatty acid ratios and the increase in autism spectrum disorders. Neurosci Biobehav Rev. 2014 Sep;45:369-78.

[3] Weiser MJ. et al. Dietary Docosahexaenoic Acid Alleviates Autistic-Like Behaviors Resulting from Maternal Immune Activation in Mice. Prostaglandins, Leukotrienes and Essential Fatty Acids (PLEFA). 2015. Dec 2.

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Jory, J. (2015). Abnormal fatty acids in Canadian children with autism Nutrition DOI: 10.1016/j.nut.2015.10.019

Endocrine disruptors and autism?

"Children with autism spectrum disorder had significantly increased serum MEHP, DEHP, and BPA [mono-(2-ethylhexyl)-phthalate (MEHP), di-(2-ethylhexyl)-phthalate (DEHP), and bisphenol A (BPA)] concentrations."

So said the findings reported by Fatih Kardas and colleagues [1] looking at whether there may be more to see when it comes to phthalate metabolism and autism among other things. For those who might be rolling their eyes at this point, I'll draw your attention to other occasions when similar results have been reported (see here and see here) and the place that the Kardas results seem to share.

This time around nearly 50 children diagnosed with an autism spectrum disorder (ASD) and some 40 asymptomatic controls provided serum samples that were screened for MEHP, DEHP, and BPA. The analytical weapon of choice was high-performance liquid chromatography (HPLC), I assume coupled to something like UV and/or fluorescence detection. The results by group suggested that "endocrine disruptors may have a role in the pathogenesis of autism spectrum disorders" according to the authors. I might add that we have had previous clues that this research was coming to publication [2].

These are interesting results. Whilst the use of HPLC (as a separative method) is not necessarily on its own the most accurate method of assaying for such compounds (that would be coupled to something like mass spectrometry) there are some potentially important things to learn from such findings. Although it would be easy to correlate such results with something like a higher exposure to such compounds in cases of autism, I'm not ready to accept that as an explanation given the frequency with which we all come into contact with them. I'd perhaps favour a hypothesis whereby the ability to metabolise such xenobiotics is differentially affected in at least some cases of autism as per the discussions by Stein and colleagues [3]. Such a metabolic difference could be a genetic issue tied into something like all that chatter about sulphation and glucuronidation and autism down the years (see here). It could also be something a little more functional in terms of how those trillions of wee beasties that call us home (the gut microbiome) might also affect such processes [4] too given the growing interest in the microbiome in relation to autism (see here). At this point I'll also draw your attention to some similarly interesting work on how functional bowel habits and gut microbiota might be linked with some autism in mind [5].

Acknowledging that autism research is still fumbling around a bit when it comes to the precise hows and whys of how environment (non-genetic factors) might fit into autism (see here) and it's relative contribution, I'm a great believer in how the technology we have at our disposal can help. The rise and rise of the various -omics and the concept of a systems biology approach with an autism slant (see here) means that we are getting better at not only analysing genetic and biological parameters but also in putting any potential connections together. Acknowledging that there may be many different types of autism (the autisms) with various different comorbidity patterns accompanying (see here), it is only a matter of time before patterns start to emerge and discussions can move on from simply genetics vs. environment.

Music: The Score - Oh My Love.

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[1] Kardas F. et al. Increased Serum Phthalates (MEHP, DEHP) and Bisphenol A Concentrations in Children With Autism Spectrum Disorder: The Role of Endocrine Disruptors in Autism Etiopathogenesis. J Child Neurol. 2015 Oct 8. pii: 0883073815609150.

[2] Kardas F. et al. P174 – 2732: Increased serum phthalates (MEHP, DEHP) and bisphenol A concentrations in children with autism: The role of endocrin disruptors in autism aetiopathogenesis. Euro J Pediatr Neurology. 2015; 19: Suppl. 1: S142-S143.

[3] Stein TP. et al. Bisphenol A Exposure in Children With Autism Spectrum Disorders. Autism Res. 2015 Jun;8(3):272-83.

[4] Rowland IR. Metabolism of Di-(2-ethylhexyl) phthalate by the contents of the alimentary tract of the rat. Food and Cosmetics Toxicology. 1974; 12: 293-302.

[5] Gabriele S. et al. Slow intestinal transit contributes to elevate urinary p-cresol level in Italian autistic children. Autism Res. 2015. October 6.

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Kardas F, Bayram AK, Demirci E, Akin L, Ozmen S, Kendirci M, Canpolat M, Oztop DB, Narin F, Gumus H, Kumandas S, & Per H (2015). Increased Serum Phthalates (MEHP, DEHP) and Bisphenol A Concentrations in Children With Autism Spectrum Disorder: The Role of Endocrine Disruptors in Autism Etiopathogenesis. Journal of child neurology PMID: 26450281

Serotonin - melatonin (and the in-betweeners) linked to autism

The paper by Pagan and colleagues [1] (open-access) looking at "serotonin, melatonin and the intermediate N-acetylserotonin (NAS) in a large cohort of patients with ASD [autism spectrum disorder] and their relatives" set the old grey-pink matter into action recently. Not only because I have some real interest in the starting material for these compounds - the aromatic amino acid known as tryptophan - but because this research group included some quite important analysis of the enzymes involved in the reaction from serotonin to melatonin with autism in mind.

Just before heading into the paper and the details, I'm gonna draw your attention to the picture shown to the right (hand drawn by yours truly) which was originally included in a blog post on something called 5-hydroxytryptophan (5-HTP). As you can see, the source material tryptophan eventually cascades down into various other compounds with serotonin and melatonin in mind. I might add that this is not the only metabolic fate of tryptophan as, for example, per another important compound set: the kynurenine pathway again talked about on this blog.

Serotonin (5-HT) for those who might not know is a neurotransmitter that represents one of the 'S' in the class of medicines called SSRIs hinting at its relationship to mood regulation among other things. Melatonin by contrast has quite an important role in functions like sleep; although, as has been previously mentioned on this blog, melatonin might be quite the molecular handyperson (see here). Both serotonin and melatonin have some history when it comes to autism research and practice (see here for example).

N-acetylserotonin (NAS) is a slightly less well-known compound when it comes to autism. A quick trawl of PubMed using the search term 'N-Acetylserotonin autism' came up with two other entries at the time of writing. Granted both the Anderson-Maes [2] and Carter and colleagues [3] make for interesting reading for different reasons, but there does seem to be a dearth of research on the possibility of a role for NAS for at least some autism.

Now, back to the Pagan paper and a few pointers even though it is open-access:

• The hypothesis: "that (i) the intermediate NAS might also be altered, (ii) alterations of the serotonin-NAS–melatonin pathway might constitute a possible biomarker for a subgroup of individuals with ASD and that (iii) they would be associated with specific clinical profiles."
• Whilst avoiding foods high in tryptophan and/or serotonin such as bananas and chocolate, morning blood samples were provided by "278 patients with ASD, their 506 first-degree relatives (129 unaffected siblings, 199 mothers and 178 fathers) and 416 sex- and age-matched controls" and various parts of the sample assayed for serotonin, melatonin and NAS. The analytical weapons of choice were HPLC (albeit with a rather antiquated method by today's mass spec / NMR standards) and ELISA among other things. A small number of urine samples were also collected and analysed for 6-Sulfatoxymelatonin.
• Results: on the whole, those with autism presented with "elevated whole-blood serotonin" whilst "Plasma melatonin was significantly decreased in individuals with ASD and their relatives compared with controls." These are not surprising results given the research history in this area. 
• With slightly more novelty: "the intermediate metabolite NAS, measured in blood platelets, was found to be significantly elevated in individuals with ASD and their relatives compared with controls." Further such elevations in platelet NAS "strongly correlated" with the plasma melatonin findings noted in cases of autism. 
• There was potentially also something to see when the results were pooled together in terms of discriminating autism from not-autism but I'll leave it up to you to decide how well their biomarkers functioned.
• Bearing in mind my diagram shown above, the increase in serotonin, increase in NAS but decrease in melatonin might provide some important information about where there may be a metabolic 'block'. In this respect, the authors' analysis of "two enzymes, AANAT [Aralkylamine N-acetyltransferase] and ASMT [N-Acetylserotonin O-methyltransferase] known to form protein complexes with 14-3-3 scaffolding proteins" is also important. Actually, authors looked at 14-3-3 in platelets and reported it/them: "significantly decreased in patients with ASD." Previous work from this group [4] had indicated that ASMT activity to be lower in cases of autism; thus suggesting that problems with this enzyme or the availability of this enzyme converting NAS to melatonin might for example, account for the lower melatonin findings.

I've gone on a little bit in this post but hope that you can see the logic in doing so. Metabolic pathways when it comes to human physiology are pretty complex things affected by all manner of variables including things like enzyme function and the availability of those all-important cofactors (see here for some chatter about BH4 for example). Pagan et al have done a good preliminary job of stitching together some important compounds with autism in mind and particularly their findings in relation to NAS. I personally am looking forward to seeing some independent replication of these findings and perhaps onwards, a little more analysis of some other tryptophan derivatives [5] potentially important to [some] autism...

A little music to close: Mark Ronson - Uptown Funk.

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[1] Pagan C. et al. The serotonin-N-acetylserotonin–melatonin pathway as a biomarker for autism spectrum disorders. Translational Psychiatry. 2014. November 11.

[2] Anderson G. & Maes M. Redox Regulation and the Autistic Spectrum: Role of Tryptophan Catabolites, Immuno-inflammation, Autoimmunity and the Amygdala. Curr Neuropharmacol. 2014 Mar;12(2):148-67.

[3] Carter MD. et al. Quantitation of melatonin and n-acetylserotonin in human plasma by nanoflow LC-MS/MS and electrospray LC-MS/MS. J Mass Spectrom. 2012 Mar;47(3):277-85.

[4] Melke J. et al. Abnormal melatonin synthesis in autism spectrum disorders. Mol Psychiatry. 2008 Jan;13(1):90-8.

[5] Anderson RJ. et al. Identification of indolyl-3-acryloylglycine in the urine of people with autism. J Pharm Pharmacol. 2002 Feb;54(2):295-8.

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Pagan C, Delorme R, Callebert J, Goubran-Botros H, Amsellem F, Drouot X, Boudebesse C, Le Dudal K, Ngo-Nguyen N, Laouamri H, Gillberg C, Leboyer M, Bourgeron T, & Launay JM (2014). The serotonin-N-acetylserotonin-melatonin pathway as a biomarker for autism spectrum disorders. Translational psychiatry, 4 PMID: 25386956

Metabolomics and autism: the continuing search for biomarkers

I'm always a happy bunny when some of my own research findings receive something like independent replication. So it was when I read the monster paper from Paul West and colleagues [1] (open-access) reporting results based on not one, not two, not three, not even four, but five mass spectrometric methods looking for potential biomarkers for autism. Metabolomics in action (see here for an introduction to this topic).

Rosina @ Wikipedia 

The particular reason for my excitement was the quote: "Creatinine was decreased in children with ASD [autism spectrum disorder] and is consistent with the findings of Whitely et al, who observed similar changes in urinary creatinine in children diagnosed with PDD [pervasive developmental disorder]" based on the results of our paper a few years back [2] (see here for further details of how I spend my spare time talking about urine). The caveat being that we (the Royal We) looked in urine and West et al looked at blood (plasma). I can also forgive the authors for spelling my name wrong too... WHITELEY.

The West paper is open-access but I'm gonna give you a few pointers nonetheless. Stick with me on this one because although quite a long post, this is important work...

• So: "The aim of the study was to perform a broad evaluation of small molecules in blood plasma to discover metabolites that may lead to biomarkers associated with ASD." 
• The value-added bit was that this was study from the MIND Institute which meant that participant groups were very well-defined in terms of diagnosis and presenting symptoms. Indeed, as per other studies of biomarkers (see here), the talk was all about study groups (ASD vs. asymptomatic controls denoted as 'typically developing' TD) and also the use of training and test sets, where: " 82 patient samples (52 ASD and 30 TD samples) were split into two sets, (1) a training set of 61 samples (39 ASD and 22 TD) for identification of statistically significant features and classification modeling and (2) a 21-sample independent validation set (13 ASD and 8 TD) used to evaluate performance of the classification models."
• So, then to the interesting bit... the mass spec methods used and data handling. A combination of liquid chromatography-high resolution mass spectrometry (LC-HRMS) and gas chromatography-mass spectrometry (GC-MS) were used. Actually the LC-HRMS was based on separation using C8 and HILIC column chromatography (the LC part) on both occasions coupled to "electrospray ionization" (the MS part) in positive and negative ion mode so giving "4 separate data acquisitions per sample." That and the GC-MS data makes 5 methods. 
• Various methods/software were used to identify potential metabolites of interest including a couple of programs we use in our lab such as "Agilent Technologies MassHunter Qualitative Analysis software" and the METLIN database.
• Results: as one might imagine, quite a few compounds/metabolites/signals were picked up across the 5 methods used. Table 2 of the paper gives you some idea of the sorts of numbers talked about. That being said, assigning a molecular formula to all those metabolites is rather another matter as per the authors note: "... 179 features comprised 3% of the LC-HRMS and 8% of the GC-MS preprocessed set of features". 'Features' by the way referred to "a moiety detected by the mass spectrometer that is defined by 2 properties 1) the detected mass-to-charge ratio (m/z) and 2) the chromatographic retention time".
• Those 179 'features' formed the basis of the statistical analyses used to try and differentiate autism from control samples. These were subsequently whittled down to: "an 80 feature set [that] exhibited the best combined classification performance metrics... with an average accuracy of 90%, an average sensitivity of 92%, an average specificity of 87%, and an average AUC [area under the curve] of 0.95."
• When moving from training to validation sets, the previous 80 feature model did not work as well. Indeed, some further statistical modelling was used and: "The results suggest that at least 40 features are needed to reach an accuracy of 70% and that a range of 80 to 160 features had the best performance with this independent validation sample set as well as the training set of samples."
• To get to the juicy details of which compounds might be the ones to watch with autism biomarkers in mind, well: "a variety of molecular classes including amino acids, organic acids, sterols, and fatty acids" came up. I've already mentioned creatinine but other prominent mentions were given to "aspartate, glutamate, DHEAS, citric acid, succinic acid, methylhexa-, tetra- and hepta-decanoic acids, isoleucine, glutaric acid, 3-aminoisobutyric acid" and homocitrulline. The authors provide a handy overview of where their results might fit with other autism research areas (e.g. mitochondrial dysfunction, the gut microbiome) which I would encourage interested readers to further peruse. I'm gonna highlight isoleucine as one example where a form of autism has already been talked about with the words 'branched chain amino acids' in mind (see here).
• The authors conclude with a need for quite a bit more study in this area: "This initial study provides proof of concept to further pursue development of metabolic biomarkers of ASD." Personally, I'd like to think that proof-of-concept is perhaps too preliminary a way of introducing metabolomics to autism research given previous research forays (see here and see here and see here) and their potentially important findings. Certainly, things need to be scaled up in terms of participant numbers [3] and also delving into those all-important subgroups of 'the autisms'. Challenges however do remain in assigning molecular formulae to all those compounds detected.

What's more to say? Well, as has been mentioned in a previous post (see here) one always needs to be a little careful when talking about biomarkers for autism as if we're talking about a homogeneous diagnosis and the search for compound X supposedly covering all that heterogeneity (and comorbidity). If we've learned anything from the genetic research on autism for example, it is that simple, universal objective markers are probably not going to be present. Given that the metabolome is to quite a large extent determined by the proteome potentially also intersecting with the microbiome, complexity is probably going to be the keyword.

That being said, I do see merit in the continued use of metabolomics as part of all that system biology kerfuffle (see here) when applied to autism research. I'd personally suggest a few tweaks to how this kind of research is carried out on the basis for example, of not necessarily using the diagnostic label of 'autism' or 'autism spectrum disorder' as a primary starting point. I've talked before on this blog about the notion of best responders and non-responders to intervention for example (see here) and how if one chose to use this as an important variable differentiating those on the spectrum, one might just see a few differences across groups. Such research might also help further inform researchers / clinicians / parents / people on the spectrum who might be best suited for certain types of intervention. Interestingly with dietary intervention in mind, the authors reported that: "Ten of the 52 ASD subjects were on a gluten and/or casein-free (GFCF) diet". Mmm...

Then to some music... Go Your Own Way by Fleetwood Mac. Or if you prefer, the Seaweed version...

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[1] West PR. et al. Metabolomics as a Tool for Discovery of Biomarkers of Autism Spectrum Disorder in the Blood Plasma of Children. PLoS One. 2014 Nov 7;9(11):e112445.

[2] Whiteley P. et al. Spot urinary creatinine excretion in pervasive developmental disorders. Pediatr Int. 2006 Jun;48(3):292-7.

[3] Roessner V. Large sample size in child and adolescent psychiatric research: the way of salvation? European Child & Adolescent Psychiatry. 2014. November 6.

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West, P., Amaral, D., Bais, P., Smith, A., Egnash, L., Ross, M., Palmer, J., Fontaine, B., Conard, K., Corbett, B., Cezar, G., Donley, E., & Burrier, R. (2014). Metabolomics as a Tool for Discovery of Biomarkers of Autism Spectrum Disorder in the Blood Plasma of Children PLoS ONE, 9 (11) DOI: 10.1371/journal.pone.0112445