Amino Acids Disturbed in Autism? Very Likely

Amino acids in your body are the building blocks for making proteins. There are essential Amino Acids that you must obtain from diet and semi-essential amino acids that in young children are body is still not able to produce and non-essential amino acids that your body can produce. 

There was an earlier post on Amino Acids:- Amino Acids in Autism 

There are also sub-groups, Branch Chained Amino Acids (BCAAs) and aromatic.  The branched chained amino acids (BCAAs) compete with the aromatic amino acids for entry into the brain. Therefore, altering BCAA levels can affect the levels of the neurotransmitters serotonin, dopamine, epinephrine and norepinephrine in the brain. 

Alanine
Arginine (essential)
Asparagine
Aspartic acid
Cysteine
Glutamic acid
Glutamine
Glycine
Histidine (essential) Aromatic
Isoleucine (essential) BCAA
Leucine (essential) BCAA
Lysine (essential)
Methionine (essential)
Phenylalanine (essential)  Aromatic
Proline
Serine
Threonine (essential)
Tryptophan (essential) Aromatic
Tyrosine  Aromatic
Valine (essential)  BCAA 

Taurine is not an amino acid, but often gets treated as if it was one.

Arginine and its derivatives appear to play a critical role in some types of cognitive impairment including Alzheimer's and other forms of dementia.

I am writing new posts about certain individual amino acids that look interesting. Aspartic acid is next and the post looks like getting rather complex, so I decided to highlight an interesting very simplistic study that I stumbled across, that would otherwise get lost in other complex papers.  

I call it simplistic because it compares a control (NT) group with two groups of children with autism, one group has no intervention and the other group is made up of kids with some intervention, of any kind, under the umbrella of digestive/dietary/enzyme/antifungal. The control group was siblings of the children with autism. So three groups in total.

Nonetheless, this Disney science does show something quite surprising. In most cases it looks like any intervention produced results much closer to the reference range than no intervention. The study did not measure whether the intervention had any effect on the severity of autism, or compare the different interventions.

Since I am currently researching Aspartic acid I was drawn to the fact that Aspartic acid was nearly three times higher for the female controls compared with the males.  This I find notable, given the sex difference in autism, which is the biggest clue nature has left us. 

Altered amino acid excretion in children with autism 

A total of 63 subjects were recruited, consisting of 34 autistic children with 31 males and three females aged 5–15 years (mean ± SD, 6.9 ± 2.5 years), and 29 controls with 13 males and 16 females also covering a range of 5–15 years (mean ± SD, 8.9 ± 3.3 years). The controls were derived primarily from siblings of the autistic group, where the sex ratio was more reflective of the general population compared to the sex balance of the autistic population which is recognised as approximately 4:1 (male:female).15 Measures were taken to account for the uneven sex-distribution in the interpretation of the results.

Twenty-two of the autistic children were receiving therapeutic treatments related to digestive function and nutritional uptake. These treatments included antifungal medication, to treat confirmed or suspected Candida infection of the digestive tract, probiotics for maintenance of gut microflora, dietary intervention (gluten- and/or casein-free diet), nutritional supplements, or the hormone secretin; this has been shown to be responsible for regulating pH of the duodenum and is, therefore, pertinent to the functioning of digestive enzymes. On this basis, the autism group was further subdivided into two groups for evaluation of urinary metabolites: treated autistic patients (n = 22; range, 5–15 years; mean, 6.9 ± 2.4 years; 91% male) and untreated autistic patients (n = 12; range, 5–12 years; mean, 7.0 ± 2.5 years; 91% male). To account for any sex-associated differences in urinary output, resulting from the disparity in the sex matching of the autistic and control groups, the control population was first subdivided on the basis of gender.

Two compounds emerged as significantly different on a gender basis for the control group: (i) glucose excretion was of a significantly higher mean concentration for the female control group compared with the males (P <0.05); and (ii) aspartic acid was nearly three times higher for the female controls compared with the males (P < 0.05). No other urinary metabolite concentrations proved to be significantly different between the female and male controls. On this basis, the data from the entire control group were compared with the treated and untreated autistic cohorts.

Plasma amino acids vs urinary amino acids 

There are numerous other studies and they do tend to use a blood test rather than a urine sample. Below is a relatively recent study from Egypt. 

Study of plasma amino acid levels in children with autism: An Egyptian sample

Methods

Twenty autistic children were compared to twenty healthy age and sex matched normal children serving as control, where serum amino acids, urea, ammonia and protein electrophoresis were estimated.

Results

As regards essential amino acid levels, autistic children had significant lower plasma levels of leucine, isoleucine, phenylalanine, methionine and cystine than controls (P < 0.05),while there was no statistical difference in the level of tryptophan, valine, threonine, arginine, lysine and histidine (P > 0.05). In non-essential amino acid levels, phosphoserine was significantly raised in autistic children than in controls (P < 0.05). Autistic children had lower level of hydroxyproline, serine and tyrosine than controls (P < 0.05). On the other hand there was no significant difference in levels of taurin, asparagine, alanine, citrulline, GABA, glycine, glutamic acid, and ornithine (P > 0.05).

There was no significant difference between cases and controls as regards the levels of urea, ammonia, total proteins, albumin and globulins (alpha 1, alpha 2, beta and gamma) (P > 0.05).

Conclusions

Autistic children had lower levels of some plasma amino acids except for glycine and glutamic acids and phosphoserine were increased with normal serum levels of urea, ammonia, total proteins, albumin and globulins (alpha 1, alpha 2, beta and gamma). 

In conclusion, autistic children may have dysregulated amino acids metabolism as all amino acids except for glutamic acid, phosphoserine and glycine are decreased in patients than in control; the raised glutamic acid may suggest involvement of an altered glutamate transporter and is consistent with a biochemical basis for autistic disorders. Also, the lower amounts of essential amino acids are correlated with more severe autism.

Conclusion

The fair conclusion is that both excreted and plasma amino acids look to be disturbed in autism. Does this tell you anything actionable? Should you become obsessed by trying to reach the reference ranges?

The answer depends on who you ask and I guess who is paying.

The derivatives of some amino acids may indeed be disturbed as a protective mechanism in which the body is adapting to specific effects of that person's autism. This was suggested in the research as one explanation of why agmatine, a derivative of arginine, is elevated in schizophrenia.  In other words elevated agmatine is a good thing in that person, it may well be a biomarker for schizophrenia, but possibly a "good" biomarker. 

If normalizing amino acids does improve autism, then expect the CM-AT treatment from Curemark to pass its phase 3 trials and become an FDA approved therapy for autism. Interestingly when I looked into the Curemark patents a long time ago, secretin appeared and it made another appearance earlier in this post. Secretin is now viewed as a false hope for autism treatment and those who still use it are seen as quacks. In trials secretin was shown not to help most people with autism, but regular readers will know that this is different from saying nobody responds. 

Irrespective of what finally happens to CM-AT, it looks like individual amino acids do have a place in some personalized autism therapies. This may, in some cases, be irrespective of the reference ranges, in other words in some cases an abnormally high level of one amino acid may be required to get a specific beneficial therapeutic effect.  Staying within the reference range is clearly the safer option.

Now I am back to my complicated post about Aspartate and N-acetylaspartate (NAA), which does look very relevant to autism.

Different Types of Excitatory/Inhibitory Imbalance in Autism, Fragile-X & Schizophrenia

There is much written in the complex scientific literature about the Excitatory/Inhibitory (E/I) imbalance between neurotransmitters in autism. 

Many clinical trials have already been carried out, particularly in Fragile-X.  These trials were generally ruled as failures, in spite of a significant minority who responded quite well in some of these trials.

As we saw in the recent post on the stage II trial of bumetanide in severe autism, there is so much “background noise” in the results from these trials and it is easy to ignore a small group who are responders.  I think if you have less than 40%, or so, of positive responders they likely will get lost in the data. 

You inevitably get a significant minority who appear to respond to the placebo, because people with autism usually have good and bad days and testing is very subjective.

There are numerous positive anecdotes from people who participated in these “failed” trials.  If you have a child who only ever speaks single words, but while on the trial drug starts speaking full sentences and then reverts to single words after the trial, you do have to take note. I doubt this is a coincidence.

Here are some of the trialed drugs, just in Fragile-X, that were supposed to target the E/I imbalance:-

Metabotropic glutamate receptor 5 (mGluR5) antagonist

·        Mavoglurant

·        Lithium

mGluR5 negative allosteric modulator

·        Fenobam

N-methyl-D-aspartic acid (NMDA) antagonist

·        Memantine

Glutamate re-uptake promoter

·        Riluzole

Suggested to have effects on NMDA & mGluR5 & GABA_A

·        Acamprosate

GABA_B agonist

·        Arbaclofen

Positive allosteric modulator (PAM) of GABA_A receptor

·        Ganaxolone

Best not to be too clever

Some things you might use to modify the E/I imbalance can appear to have the opposite effect, as was highlighted in the comments in the post below:-

NMDAR hypo-function causing E/I imbalance in Autism and Schizophrenia – Baclofen, Sodium benzoate and Cinnamon (again)

So whilst it is always a good idea to try and figure things out, you may end up getting things the wrong way around, mixing up hypo and hyper.

The MIT people who work on Fragile-X are really clever and they have not figured it all out.

Fragile-X and Idiopathic Autism

Fragile-X gets a great deal of attention, because its biological basis is understood.  It results in a failure to express the fragile X mental retardation protein (FMRP), which is required for normal neural development.

We saw in the recent post about eIF4E, that this could lead to an E/I imbalance and then autism.

eIF4E inhibitors for Autism – Why not Ribavirin?

Our reader AJ started looking at elF4E and moved on to EIF4E- binding protein number 1.

In the green and orange boxes below you can find elF4E and elF4E-BP2.

This has likely sent some readers to sleep, but for those whose child has Fragile-X, I suggest they read on, because it is exactly here that the lack of fragile X mental retardation protein (FMRP) causes a big problem.  The interaction between FMRP on the binding proteins of elF4E, cause the problem with neuroligins (NLGNs), which causes the E/I imbalance.  Look at the red oval shape labeled FMRP and green egg-shaped NLGNs.

In which case, while AJ might naturally think Ribavirin is a bit risky for idiopathic autism, it might indeed be very effective in some Fragile-X.  You would hope some researcher would investigate this.

Can you have more than one type of E/I imbalance?

Readers whose child responds well to bumetanide probably wonder if they have solved their E/I imbalance.

I think they have most likely improved just one dysfunction that fits under the umbrella term E/I imbalance.  There are likely other dysfunctions that if treated could further improve cognition and behavior.

On the side of GABA, it looks like turning up the volume on α3 sub-unit and turning down the volume on α5 may help. We await the (expensive) Down syndrome drug Basmisanil for the latter, given that the cheap 80 year old drug Cardiazol is no longer widely available. Turning up the volume on α3 sub-unit can be achieved extremely cheaply, and safely, using a tiny dose of Clonazepam.

It does appear that targeting glutamate is going to be rewarding for at least some of those who respond to bumetanide.

One agonist of NMDA receptors is aspartic acid. Our reader Tyler is a fan of L-Aspartic Acid, that is sold as a supplement that may boost athletic performance.  

Others include D-Cycloserine, already used in autism trials; also D-Serine and L-Serine.

D-Serine is synthesized in the brain from L-serine, its enantiomer, it serves as a neuromodulator by co-activating NMDA receptors, making them able to open if they then also bind glutamate. D-serine is a potent agonist at the glycine site of NMDA receptors. For the receptor to open, glutamate and either glycine or D-serine must bind to it; in addition a pore blocker must not be bound (e.g. Mg2+ or Pb2+).

D-Serine is being studied as a potential treatment for schizophrenia and L-serine is in FDA-approved human clinical trials as a possible treatment for ALS/Motor neuron disease.  

You may be thinking, my kid has autism, what has this got to do with ALS/Motor neuron disease (from the ice bucket challenge)? Well one of the Fragile-X trial drugs at the beginning of this post is Riluzole, a drug developed for specially for ALS.  Although it does not help that much in ALS, it does something potentially very useful for some autism, ADHD and schizophrenia; it clears away excess glutamate.

Fragile-X is likely quite different to many other types of autism

I suspect that within Fragile-X there are many variations in the downstream biological dysfunctions and so that even within this definable group, there may be no universal therapies.  So for some people an mGluR5 antagonist may be appropriate, but not for others.

Even within this discrete group, we come back to the need for personalized medicine.

I do not think Fragile-X is a good model for broader autism.

Glutamate Therapies

There are not so many glutamate therapies, so while the guys at MIT might disapprove, it would not be hard to apply some thoughtful trial and error.

You have:

mGluR5

     ·        mGluR5 agonists (only research compounds)

·        mGluR5 positive allosteric modulators (only research compounds)

·        mGluR5 antagonists (Mavoglurant, Lithium)

·        mGluR5 negative allosteric modulators (Fenobam, Pu-erh tea decreases mGluR5 expression )

Today you can only really treat too much mGluR5 activity.  It there is too little activity, the required drugs are not yet available.  I wonder how many people with Fragile-X are drinking Pu-erh tea, it is widely available.

NMDA agonists

D-Cycloserine an antibiotic with similar structure to D-Alanine (D-Cycloserine was trialed in autism and schizophrenia)

ɑ-amino acids:

·         Aspartic acid (trialed and used  by Tyler, suggested for schizophrenia)

·         D-Serine (trialed in schizophrenia)

•    L-Serine

• D-Alanine (trialed in schizophrenia)

• L-Alanine

NMDA antagonists

·        Memantine (widely used off-label in autism, but failed in clinical trials)

·        Ketamine (trialed intra-nasal in autism)

Glutamate re-uptake promoters via GLT-1

·        Riluzole

·        Bromocriptine

·        Beta-lactam antibiotics