Showing posts with label T3. Show all posts
Showing posts with label T3. Show all posts

Thursday, 17 May 2018

Statins, SLOS and Hypocholesteraemia – Going Nowhere Fast

Today’s post is about cholesterol, statins and autism. There is a well-documented condition associated with autism called SLOS (Smith-Lemli-Opitz Syndrome). It is caused by mutations in the DHCR7 gene encoding the enzyme that catalyzes the final step in cholesterol biosynthesis.

Toe syndactyly (webbed toes), one symptom of SLOS

Reduced activity of the enzyme 7DHCR typically leads to low levels of cholesterol, but markedly increased levels of precursor 7DHC (and its isomer, 8DHC) in blood and tissues. Typical SLOS manifestations include intellectual disability, growth retardation, minor craniofacial anomalies, microcephaly and 2-3 toe syndactyly (webbed toes).
SLOS is rare, but some cases do get missed because you can have a DHCR7 mutation and have normal levels of cholesterol and have normal cognitive function.

Cholesterol and the blood brain barrier (BBB)
You do have a lot of cholesterol in your brain, but it does not cross the blood brain barrier (BBB), it was made in the brain.  Eating more cholesterol can have no direct effect on cholesterol levels in the brain.
The standard treatment for SLOS has long been oral cholesterol supplementation, but there is no conclusive research to show it helps. There is plenty of anecdotal evidence.

Simvastatin and SLOS
Simvastatin is a drug widely used drug to treat people with elevated cholesterol.
There has been anecdotal evidence that Simvastatin improves SLOS and recently a very thorough study was carried out to establish whether or not it really has a benefit.
In reality the study was comparing:

Simvastatin + cholesterol supplement  vs  cholesterol supplement

The study was carried out by researchers including Dr Richard Kelley (“Dr Mitochondria”) and Dr Elaine Tierney (“Dr Cholesterol”)

Currently, most SLOS patients are treated with dietary cholesterol supplementation. Although cholesterol therapy reduces serum 7-DHC concentrations to a degree, significant amounts of 7-DHC persist even after years of therapy.  Anecdotal case studies and case series support the idea that cholesterol supplementation benefits the overall well-being of SLOS patients; however, the effects of dietary cholesterol supplementation on cognitive or behavioral aspects of this disorder have not been reported by others or substantiated in a limited controlled trial. The efficacy of dietary cholesterol supplementation is probably limited by the inability of dietary cholesterol to cross the blood–brain barrier. Moreover, increased concentrations of 7-DHC or 7-DHC-derived oxysterol could have toxic effects. Specialists have hypothesized that, in patients with mild to classic SLOS, many aspects of the abnormal behavioral and cognitive phenotype could be the result of altered sterol composition in the central nervous system. Thus, interventions that ameliorate the central nervous system biochemical disturbances in SLOS are critical to understanding the pathological processes that underlie this inborn error of cholesterol synthesis and to developing effective therapies to treat the neurological deficits.

Expression of DHCR7 is regulated by SREBP2, which, when activated by low levels of cholesterol in the endoplasmic reticulum, increases the transcription of most genes of the cholesterol synthetic pathway. Having shown that DHCR7 expression is increased in SLOS fibroblasts treated with simvastatin,31 we hypothesized that the paradoxical increase in serum cholesterol could be the result of increased expression of a DHCR7 allele with residual enzymatic function, and we demonstrated that many DHCR7 alleles encode an enzyme with residual activity. Furthermore, both in vitro experiments with human  fibroblasts and in vivo experiments using hypomorphic Dhcr7T93M/delta mice support the hypothesis that increased expression of DHCR7 alleles with residual enzymatic activity can significantly improve plasma and tissue sterol concentrations. Because residual DHCR7 activity varies among patients with SLOS, this hypothesis could explain the paradoxical increase in cholesterol in some patients and the adverse reactions observed in others.

In this study we also evaluated the potential of simvastatin to alter specific aspects of the SLOS behavioral phenotype. Our secondary outcome measures were the CGI-I and ABC-C irritability scores. Although we observed no significant effect on the CGI-I, we did observe significant improvement in the ABC-C irritability score (Figure 4). This article therefore represents the first controlled study to demonstrate improved behavior in subjects with SLOS in response to a therapeutic intervention.

In summary, this study represents the first controlled trial of simvastatin therapy in SLOS and the first controlled trial demonstrating the potential of drug therapy to modulate sterol composition and to improve behavior in SLOS. We have established that treatment with simvastatin is relatively safe, can decrease DHC levels, and can improve at least one aspect of the behavioral phenotype. These data support continued efforts to identify and rigorously evaluate potential therapies that may have clinically meaningful benefits for patients with SLOS.

Plasma sterol levels

Cholesterol and dehydrocholesterol (7DHC + 8DHC) levels were measured at baseline (B), washout (W, 14 mo) as well as at 1, 3, 6, 9 and 12 months in both the placebo and simvastatin treatment phase. Plasma cholesterol levels (A, B) and DHC (C, D) decreased significantly during the simvastatin phase compared to the placebo phase. The plasma DHC/Total Sterol ratio (E, F), which was the primary outcome measure of this study, also decreased significantly. Data expressed as mean ± SEM.

Hypocholesterolemia (low cholesterol) and some Autism
Ten years ago, Tierney and Kelley published research showing that about 20% of autism is associated with very low cholesterol levels (less than the 5th centile for typical young people) but in their sample of 100, none had an abnormally increased level of 7DHC consistent with the diagnosis of SLOS or abnormal level of any other sterol precursor of cholesterol.

Tierney went on to patent cholesterol as a therapy for autism.

The present invention relates to the field of autism. More specifically, the present invention provides methods for treating individuals with autism spectrum disorder. Accordingly, in one aspect, the present invention provides methods for treating patients with autism spectrum disorder. In one embodiment, a method for treating an autism spectrum disorder (ASD) in a patient comprises the step of administering a therapeutically effective amount of cholesterol to the patient. In more specific embodiments, the ASD is autism, Asperger's disorder, pervasive developmental disorder-not otherwise specified (PDD-NOS), Rett's syndrome and childhood disintegrative disorder. In one embodiment, the patient has autism. 

Tierney has a clinical trial registered that was to start in 2009.

Three sites (Kennedy Krieger Institute [KKI], Ohio State University [OSU], and the National Institutes of Health [NIH]) will collaborate to accomplish the objectives of this study. In addition to defining the frequency of altered cholesterol homeostasis in ASD, 60 youths (20 at each site) with ASD plus hypocholesterolemia will enter a 12-week, double-blind, placebo-controlled trial immediately followed by a 12-week open-label cholesterol trial to test the efficacy of dietary cholesterol supplementation. Outcome measures will include standard tests of behavior, communication, and other autism features.

It appears that the study has not been completed.

Dr. Elaine Tierney and her colleagues are studying different metabolic disorders that can present with autism spectrum disorder through the Autism Metabolic Research Program at Kennedy Krieger. In 2000 and 2001, this group of researchers identified that Smith-Lemli-Opitz-Syndrome (SLOS) is associated with autism spectrum disorder. Since SLOS is known to be caused by a defect in the body's biosynthesis of cholesterol, SLOS may provide clues to the biochemistry of other autism spectrum disorders (ASD).

Dr. Tierney and colleagues published a paper in 2006, in the American Journal of Medical Genetics Part B (Neuropsychiatric Genetics), in which they describe finding that a subgroup of children with ASD have abnormally low cholesterol levels. The children's low cholesterol levels were apparently due to a limited ability to make cholesterol. This finding, in concert with their work with SLOS, has led them to believe that cholesterol may play a role in the cause of some cases of autism spectrum disorder. Dr. Tierney and colleagues at Kennedy Krieger, the National Institutes of Health and Ohio State University are performing a double-blind placebo-controlled study of cholesterol in individuals with ASD.

Cholesterol as a marker of inflammation
Nowadays, hypercholesterolemia and inflammation are considered as “partners in crime”.  Statins do lower bad cholesterol, but they also have broad anti-inflammatory effects.

Arteries do clog up with cholesterol, but a big part of why this happens is inflammation. Cholesterol deposits are initially a protective mechanism, like a band-aid. Treat the inflammation and cholesterol will not need to be deposited.
An altered immune response is a feature of many people’s autism, and you can measure it.
As Paul Ashwood’s research has shown, there are different immune sub-groups that people with autism fall into, and so you could treat each cluster with a specific therapy.

Cholesterol and Thyroid Hormones
Your thyroid produces hormones that control your metabolism. Metabolism is the process your body uses to convert food and oxygen into energy.

Your body converts the circulating pro-hormone T4 into the active hormone T3 locally. So, in your brain T4 has to be converted to T3. If you lack enough T4 coming from your thyroid gland or the special enzyme called D2 you are going to feel lethargic.
Your body needs thyroid hormones to make cholesterol and to get rid of the cholesterol it doesn’t need. When thyroid hormone levels are low (hypothyroidism), your body doesn’t break down and remove LDL (“bad”) cholesterol as efficiently as usual. Elevated LDL cholesterol will show up in your blood tests.
Hyperthyroidism has the opposite effect on cholesterol. It causes cholesterol levels to drop to abnormally low levels.
So best to check thyroid function and cholesterol levels.

My main interest is autism with a tendency to big heads (hyperactive growth signalling pathways) and an overactive immune system. This is the opposite of SLOS and hypocholesterolemia (low cholesterol).
For the 20% with low cholesterol, I think this is a very important biomarker.

.Is supplemental cholesterol the answer? I am not so sure it is.
Hopefully one day soon Dr Tierney, at Kennedy Krieger, will publish her results of cholesterol as a therapy for people with autism and low cholesterol.
For me it is good to see that Simvastatin was well tolerated in a 12 month long trial in children from 4 to 18 years of age. I have the very similar drug, Atorvastatin, in my Polypill.
Interestingly, in a paper that I will cover in later post, increasing HDL (good cholesterol), a feature of Atorvastatin and Simvastatin, was one marker of behavioral improvement in the Ketogenic Diet.

Wednesday, 14 December 2016

Refining Antioxidant (ROS & RNS) Therapy in Autism -  Selenium and Molybdenum

Today’s post is about further refining antioxidant therapy.

As we saw in a recent post, oxidative and nitrosative stress is a very common feature of autism and is treatable with OTC products.

The cheapest antioxidant, N-acetylcysteine (NAC), looks to be the best one, but there are numerous others with exotic names and equally exotic prices.

Today we just look at selenium and molybdenum.  Selenium was on my to-do list for a long time because it affects some key enzymes call GPX (glutathione peroxodases).
Molybdenum was enthusiastically recommended in a recent comment and this blog has previously touched on Molybdenum Cofactor Sulfurase (MOCOS).

Rather surprisingly, there is a commercial product that contains NAC, Selenium and Molybdenum. 

Selenium and GPX (glutathione peroxodases)

There are eight different glutathione peroxodases, but GPx1, GPx2, GPx3, and GPx4 are all made from selenium.

GPX speeds up the antioxidant reactions that involve glutathione (GSH).

In autism we know that both GSH and GPX are lacking.

We know how to make more GSH, just take some NAC.  But what about the catalyst GPX? 
There may be an equally easy way to increase that. 

Selenium and Thyroid  Enzymes

Selenium is also part of the three deiodinase enzymes D1, D2 and D3.

The active thyroid hormone is called T3, but most of what is circulating in your body is the inactive pro-hormone form called T4.

Deiodinase 1 (D1)  both activates T4 to produce T3 and inactivates T4. Besides its increased function in producing extrathyroid T3, its function is less well understood than D2 or D3.

Deiodinase 2 (D2), located in the ER membrane, converts T4 into T3 and is a major source of the cytoplasmic T3 pool.  It looks like some people with autism may lack D2 in their brain.

Deiodinase 3 (D3) prevents T4 activation and inactivates T3. It looks like some people with autism have too much D3 in their brain.

D2 and D3 are important in homeostatic regulation in maintaining T3 levels at the plasma and cellular levels.

·        In hyperthyroidism D2 is down regulated and D3 is upregulated to clear extra T3

·        in hypothyroidism D2 is upregulated and D3 is downregulated to increase cytoplasmic T3 levels

Serum T3 levels remain fairly constant in healthy individuals, but D2 and D3 can regulate tissue specific intracellular levels of T3 to maintain homeostasis since T3 and T4 levels may vary by organ.  

It appears that some people with autism may have central hyperthyroidism, meaning in their brain.

Regular readers may recall this post:-

The major source of the biologically active hormone T3 in the brain is the local intra-brain conversion of T4 to T3, while a small fraction comes from circulating T3. 

As evidence derived from in vitro studies suggests, in response to oxidative stress D3 increases while D2 decreases (Lamirand et al., 2008; Freitas et al., 2010).  As we know in the autistic brain we have a lot of oxidative stress.

Furthermore, in ASD, the lower intra-brain T3 levels occur in the

Absence of a systemic T3 deficiency (Davis et al., 2008), most likely due to the increased activity of D3.

So in some autistic brains we have too much D3 which is inactivating T3 and preventing T4 being converted to T3.

Reduced D2 is reducing the conversion of T4 to T3. 

We would therefore want to increase D2 in some autism.

This can be achieved by:-

·        Reducing oxidative stress, which we are already sold on. 

·        We can also potentially upregulate the gene that produces D2 using some food-based genetic therapy. Kaempferol (KPF) appears to work and may explain why broccoli sprout powder makes some people go hyper and some others cannot sleep  

The cAMP-responsive gene for type 2 iodothyronine deiodinase (D2), an intracellular enzyme that activates thyroid hormone (T3) for the nucleus, is approximately threefold upregulated by KPF

·        Perhaps low levels of selenium differentially affect the synthesis of D1, D2 and D3?


Where does selenium come from? 

We know from Chauham/James that selenium levels are reduced in autism, but we also know that selenium levels vary widely by geography.  

You get selenium from your diet and the level of selenium in the soil varies widely.  It is widely held that most healthy people should have plenty selenium in their diet. 

In the following paper there is an analysis of Selenium status in Europe and the Middle East.
Since we have plenty of Polish readers I have included the chart with the Polish data (on the left).  It shows that Polish people may be a little deficient in selenium.
You can see the level of selenium in Poland is below that needed to optimise plasma GPx activity.
So if you already have reduced GPx activity, because of autism, and you really need to make the most of your limited glutathione (GSH) because you have oxidative/nitrosative stress, then a little extra selenium could be just what the doctor should have ordered.


Se is an essential non-metal trace element [3] that is required for selenocysteine synthesis and is essential for the production of selenoproteins [4]. Selenoproteins are primarily either structural or enzymatic [2], acting as catalysts for the activation of thyroid hormone and as antioxidants, such as glutathione peroxidases (GPxs) [5]. GPx activity is commonly used as a marker for Se sufficiency in the body [6], where serum or plasma Se concentrations are believed to achieve maximum GPx expression at 90–100 μg/L (90.01 μg/L as proposed by Duffield and colleagues [7] and 98.7 μg/L according to Alfthan et al. [8]). However, plasma selenoprotein P (SEPP1) concentration is a more suitable marker than plasma GPx activity [9]. Prospective studies provide some evidence that adequate Se status may reduce the risk of some cancers, while elevated risk of type 2 diabetes and some cancers occurs when the Se concentration exceeds 120 μg/L [10]. Higher Se status has been linked to enhanced immune competence with better outcomes for cancer, viral infections, including HIV progression to AIDS, male infertility, pregnancy, cardiovascular disease, mood disorders [2] and, possibly, bone health [11–14].


Selenium and NAC for Rats with TBI

Perhaps not surprisingly, selenium and NAC have been found beneficial for Rats unfortunate enough to have sufferred a traumatic brain injury (TBI).

It has been suggested that oxidative stress plays an important role in the pathophysiology of traumatic brain injury (TBI). N-acetylcysteine (NAC) and selenium (Se) display neuroprotective activities mediated at least in part by their antioxidant and anti-inflammatory properties although there is no report on oxidative stress, antioxidant vitamin, interleukin-1 beta (IL)-1β and IL-4 levels in brain and blood of TBI-induced rats. We investigated effects of NAC and Se administration on physical injury-induced brain toxicity in rats. Thirty-six male Sprague–Dawley rats were equally divided into four groups. First and second groups were used as control and TBI groups, respectively. NAC and Se were administrated to rats constituting third and forth groups at 1, 24, 48 and 72 h after TBI induction, respectively. At the end of 72 h, plasma, erythrocytes and brain cortex samples were taken. TBI resulted in significant increase in brain cortex, erythrocytes and plasma lipid peroxidation, total oxidant status (TOS) in brain cortex, and plasma IL-1β values although brain cortex vitamin A, β-carotene, vitamin C, vitamin E, reduced glutathione (GSH) and total antioxidant status (TAS) values, and plasma vitamin E concentrations, plasma IL-4 level and brain cortex and erythrocyte glutathione peroxidase (GSH-Px) activities decreased by TBI. The lipid peroxidation and IL-1β values were decreased by NAC and Se treatments. Plasma IL-4, brain cortex GSH, TAS, vitamin C and vitamin E values were increased by NAC and Se treatments although the brain cortex vitamin A and erythrocyte GSH-Px values were increased through NAC only. In conclusion, NAC and Se caused protective effects on the TBI-induced oxidative brain injury and interleukin production by inhibiting free radical production, regulation of cytokine-dependent processes and supporting antioxidant redox system.



And now to Molybdenum 

Molybdenum (Mo) is a trace dietary element necessary for human survival.

Low soil concentration of molybdenum in a geographical band from northern China to Iran results in a general dietary molybdenum deficiency, and is associated with increased rates of esophageal cancer.  Compared to the United States, which has a greater supply of molybdenum in the soil, people living in those areas have about 16 times greater risk for esophageal cancer.
So you would not want to have molybdenum deficiency.

Four Molybdenum-dependent enzymes are known, all of them include molybdenum cofactor (Moco) in their active site: sulfite oxidase, xanthine oxidoreductase, aldehyde oxidase, and mitochondrial amidoxime reductase.

Moco cannot be taken up as a nutrient, and thus it requires to made in your body from molybdenum.

If your body cannot make enough Moco you may develop what is called molybdenum cofactor deficiency, which would ultimately kill you. It is ultra rare.

Symptoms include early seizures, low blood levels of uric acid, and high levels of sulphite, xanthine, and uric acid in urine.

When caused by a mutation in the MOCS1 gene it is called the type A variant.

Molybdenum cofactor deficiency may indeed be extremely rare, but MOCS1 is a known autism gene.  Perhaps there exists partial molybdenum cofactor deficiency, which is not rare at all?

Source:-  Identification of candidate intergenic risk loci in autism spectrum disorder

MOCOS (Molybdenum cofactor sulfurase)

Molybdenum cofactor sulfurase is an enzyme that in humans is encoded by the MOCOS gene.

MOCOS sulfurates the molybdenum cofactor of xanthine dehydrogenase (XDH) and aldehyde oxidase (AOX1), which is required for their enzymatic activities.

MOCOS is downregulated in autism and is suggested to induce increased oxidative-stress sensitivity, which would not be good.

So it looks like we need a clever way to upregulate MOCOS.

You need adequate molybdenum cofactor (Moco), for which you do need adequate molybdenum.

You need the genes MOCS1 and MOCOS to be correctly expressed.

SIRT1 activation, which is a future therapy for Alzheimer’s, is suggested to increase MOCOS, as may NRF2.

Sirtuin-activating compounds (STAC) are chemical compounds having an effect on sirtuins, a group of enzymes that use NAD+ to remove acetyl groups from proteins. They are molecules able to prevent aging related diseases like Alzheimer's, diabetes, and obesity.  There is quite a long list that includes ranges from polyphenols such as resveratrol, the flavonols fisetin, and quercetin also butein, piceatannol, isoliquiritigenin,

Fisetin is found in strawberries, cucumbers and supplements.  In normal animals, fisetin can improve memory; it also can have an effect on animals prone to Alzheimer's.

Here is the excellent French paper on MOCOS:-

With an onset under the age of 3 years, autism spectrum disorders (ASDs) are now understood as diseases arising from pre- and/or early postnatal brain developmental anomalies and/or early brain insults. To unveil the molecular mechanisms taking place during the misshaping of the developing brain, we chose to study cells that are representative of the very early stages of ontogenesis, namely stem cells. Here we report on MOlybdenum COfactor Sulfurase (MOCOS), an enzyme involved in purine metabolism, as a newly identified player in ASD. We found in adult nasal olfactory stem cells of 11 adults with ASD that MOCOS is downregulated in most of them when compared with 11 age- and gender-matched control adults without any neuropsychiatric disorders. Genetic approaches using in vivo and in vitro engineered models converge to indicate that altered expression of MOCOS results in neurotransmission and synaptic defects. Furthermore, we found that MOCOS misexpression induces increased oxidative-stress sensitivity. Our results demonstrate that altered MOCOS expression is likely to have an impact on neurodevelopment and neurotransmission, and may explain comorbid conditions, including gastrointestinal disorders. We anticipate our discovery to be a fresh starting point for the study on the roles of MOCOS in brain development and its functional implications in ASD clinical symptoms. Moreover, our study suggests the possible development of new diagnostic tests based on MOCOS expression, and paves the way for drug screening targeting MOCOS and/or the purine metabolism to ultimately develop novel treatments in ASD.  

Lately, a diminished seric expression of glutathione, glutathione peroxidase, methionine and cysteine has been highlighted in a meta-analysis from 29 studies on ASD subjects.45 Along this line, purines and purine-associated enzymes are recognized markers of oxidative stress. ROS are generated during the production of uric acid, catalyzed by xanthine oxidase and XDH.46 Conversely, uric acid is nowadays recognized as a protective factor acting as a ROS scavenger.47, 48 Interestingly, allopurinol, a xanthine oxidase inhibitor, was found efficient in reducing symptoms, especially epileptic seizures, in ASD patients displaying high levels of uric acid.49 However, in our cohort, only 3 out of 10 patients exhibited an abnormal uric acid secretion. It can therefore be postulated that still unknown other MOCOS-associated mechanisms may have a role in the unbalanced stress response observed in ASD OSCs.
Identifying and manipulating downstream effectors of MOCOS will be the next critical step to better understand its mechanisms of action. In parallel, we plan to ascertain some of its upstream regulators. For example, bioinformatic analyses revealed that the promoter region of MOCOS includes conserved binding sites for transcription factors such as GATA3 and NRF2. In addition, other putative interactors, such as the NAD-dependent deacetylase sirtuin-1 (SIRT1), may have a regulatory role on MOCOS expression. Interestingly, these three genes have been associated with ASD, fragile X syndrome, epilepsy and/or oxidative stress.54, 55, 56, 57 In conclusion, our study opens an unexplored new avenue for the study of MOCOS in ASD, and could set bases for the development of new diagnostic tools as well as the search of new therapeutics.


It looks like a little extra selenium may be in order to increase those GPx enzymes that are need to speed up aspects of the antioxidant activity of GSH.

When it comes to molybdenum, things get much more complex. You certainly do not want to be deficient in molybdenum and you do not want Molybdenum cofactor deficiency; you also do not want molybdenum cofactor Sulfurase (MOCOS) mis-expression.

It is fair to say that quite likely there is a problem related to molybdenum that affects oxidative stress in autism; but it is not yet clear what to do about it.  I rather doubt the solution is as simple as just a little extra molybdenum, but it is easy to try.

On the plus side, we see that if you have autism, epilepsy and high uric acid you are likely to benefit from allopurinol, which also seems to help in COPD.

There is nothing new about allopurinol possibly be effective in some autism, as from this 25 year old book, Diagnosis and Treatment of Autism.

Again we see that activating NRF2 looks a good idea, that applies to both autism and COPD.
One thing to note is that NRF2 activators are good for cancer prevention, but if you have a cancer you want NRF2 inhibitors.

NRF2 activators include sulforaphane (SFN), R-alphalipoic acid (ALA), resveratrol and curcumin.  SFN is by far the most potent.  Resveratrol and curcumin have a problem with bioavailability.

Thursday, 8 May 2014

Oxidative Stress, Central Hypothyroidism, Autism and You

   Warsaw University of Life Sciences, Source: Wikipedia

Regular readers of this blog will have noticed there are some strange things going on related to endocrinology in the autistic brain; in effect there are low levels of certain critical hormones.

We saw in research from the Harvard Medical School that it seemed that oxidative stress in the brain affected the level of a key enzyme D2 (iodothyronine deiodinase type 2).  D2 has an important role; it converts the passive thyroid pro-hormone T4,  into the active thyroid hormone T3.  Without enough T3, you are said to be hypothyroid.  When the brain is affected, it is called central hypothyroidism.

As T3 is essential for cellular metabolism, growth and differentiation, and thus critical for brain development, thyroid deficiency during embryonic or early postnatal periods would likely lead to developmental abnormalities, including autism.

Now we have some follow up research from Harvard and Warsaw University.  The paper is more readable than many scientific papers, so click on the full version below.

“While the mechanism responsible for the decrease in brain T3 levels in ASD is unclear, the relationship between T3 and Hg (mercury) should not be that easily dismissed.

Our recent animal study of perinatal mercury exposure in rats supports the possibility that the environmental toxicants can affect brain deiodinases and thus affect brain TH (thyroid hormone) status even in absence of systemic hormonal deregulation

Total Hg levels were determined in human postmortem cerebellar and brain stem samples derived from both male and female ASD cases. The results of this analysis, presented in Fig. 4 as the male and female combined data, indicate no significant difference in Hg levels between control and ASD cases in either the brainstem or the cerebellar samples.

Thus, changes in oxidative stress levels reported here could also modulate D2 activity. It is of interest that TH regulates GSH levels in the developing brain and treatment of astrocyte cultures with TH results in increased GSH levels and improved antioxidant defense, suggesting that TH plays a positive role in maintaining GSH homeostasis and protecting the brain from oxidative stress. Thus lower T3 levels in ASD brain may exacerbate the oxidative stress.

The results presented here suggest that putamen is the brain region that exhibits not only an increase in oxidative stress and a decrease in T3 levels, but also most prominent changes in gene expression in ASD. Interestingly, the putamen's main function is to regulate movements and influence reinforcement and implicit learning, processes that rely on interaction with the environment; abnormal sensory reactions are part of autistic pathology. Thus, present study further implicates this brain region in autistic pathology.

Decreased brain TH levels and changes in gene expression in ASD brains, suggested by the present study, are likely to impact the developing brain and have clinical implications. It has been previously observed that deficiency of T3 during early postnatal periods impacts basic stages of development i.e. neurogenesis, cell migration of, and synaptogenesis that could contribute to downstream functional and structural damages observed in ASD brains. At this point, because the instability of D2 in the postmortem tissue and lack of detectable D3 activity we can only speculate on the molecular mechanisms involved in decreased TH in ASD brains. However, present data suggest that the role of TH in ASD pathology should not be dismissed prematurely and certainly requires further study, especially since correction of TH deficiency may offer new therapies.

Our results showed, for the first time, brain region-specific decrease in TH levels in the cortical regions of ASD male cases. Data reported here, although derived from a limited sample size, suggest the possibility of brain region-specific disruption of TH homeostasis in autistic brain. Furthermore, brain region-specific changes in TH-dependent gene expression reported here suggest disruption of gene expression that could possibly impact the developing brain and contribute to the autistic pathology. While the postmortem instability of brain deiodinases precluded further molecular studies, the role of TH in ASD pathology and TH-based new therapies warrant future studies.

The expression of several thyroid hormone (TH)-dependent genes was altered in ASD. Data reported here suggest the possibility of brain region-specific disruption of TH homeostasis and gene expression in autism. “


We know that T3 is reduced in the autistic brain.  This may be because oxidative stress has reduced the level of the enzyme D2, but we cannot be sure, because the brain samples are old and D2 will decay with time.

The authors clearly hope that thyroid hormone-based therapies for autism will emerge.  Autistic people are likely to be euthyroid, so in their blood the thyroid levels are just fine; it is just in the brain the level of T3 is low. A successful therapy would raise the level of T3 in the brain, without affecting the level of T3 in the blood.

Reducing oxidative stress (if present) can only do good.  This is easily done with N-acetylcysteine (NAC).  If giving NAC reduces stimming/stereotypy, then the odds are that you have oxidative stress.  Oxidative stress appears to be chronic, it never goes away; you can treat it, but you cannot cure it.  We also saw this is the asthma research, where smokers were resistant to asthma drugs.  Even decades after ceasing to smoke, oxidative stress lingered and reduced the effectiveness of drugs.  In asthma the treatment for oxidative stress is NAC.

If you want a diagnostic test to establish central hypothyroidism (without any injections), this is easy.  Just give a small dose of T3 for a few days.  Before the thyroid has time to reduce its natural thyroid output, there will be a temporary increase in brain T3 levels.  If behavior improves notably for a day or two and then reverts, you have established a case of central hypothyroidism and seen how it affects behavior.

The scientific method of determining central hypothyroidism uses a test called the TRH stimulation test; but you do not get to see how behavior changes when T3 increases in the brain.

Also, note again that while mercury is definitely very bad for you, the study showed that the brains of people with autism had no more mercury than the control group.

We also see that while oxidative stress may cause a reduction in brain T3 levels, low T3 levels promote further oxidative stress.  So it is a self-perpetuating process.  This brings us back again to my venn diagram, where everything is inter-related.