Showing posts with label Parkinson's. Show all posts
Showing posts with label Parkinson's. Show all posts

Thursday, 5 April 2018

Transcutaneous Vagal Nerve Stimulation - a Potential Cognitive Therapy?

 Sham device left and the real one on the right

In older posts there was quite a lot written about the vagal nerve and a method of stimulating it, called vagal nerve stimulation (VNS). VNS is already used by many thousands of people with epilepsy; more recently a much milder kind of stimulation has been developed to improve learning after a stroke.
This kind of therapy requires a 40 minute operation to attach the device inside the body. Even though it looks like VNS makes a dramatic improvement in rehabilitation following a stroke, I do not see children without epilepsy being fitted with internal VNS devices any time soon.
Traditionally VNS requires making a connection directly to the main vagus nerve, however the vagus nerve has many branches leading to it.
A German company Cerbomed has created a non-invasive, transcutaneous (through the skin) VNS device (tVNS) that stimulates the afferent auricular branch of the vagus nerve located in your ear.
“This device has received CE approval as indication that it complies with essential health and safety requirements. Thus, tVNS is safe and accompanied only by minor side effects such as slight pain, burning, tingling, or itching sensation under the electrodes.  
Given that the right vagal nerve has efferent fibers to the heart, tVNS is safe to be performed only in the left ear.”
There are several kinds of electric and magnetic stimulation already used in autism - Transcranial Magnetic Stimulation (TMS), transcranial direct current stimulation (tDCS) and ECT.
ECT was covered in this post:-

Manuel Casanova, neuropathologist and bilingual autism blogger is a fan of TMS

Transcranial direct current stimulation (tDCS) is a form of neurostimulation that uses constant, low direct current (DC) delivered via electrodes on the head; it can be contrasted with cranial electrotherapy stimulation which generally uses alternating current (AC) the same way.
It was originally developed to help patients with brain injuries or psychiatric conditions like major depressive disorder.


The authors present a case of an 18-year old patient with ASD treated successfully with tDCS; 1.5 mA of tDCS was applied once a day for 30 minutes for 8 consecutive days with the anode electrode over rTPJ (CP6 in the 10/10 electroencephalogram system) and the cathode electrode placed on the ipsilateral deltoid. Behavioral outcome was assessed using the Autism Treatment Evaluation Checklist prior to tDCS, after the final tDCS session, and at 2 months after tDCS. An additional, informal follow-up was also made 1 year after tDCS.


Autism Treatment Evaluation Checklist showed substantial improvement in social functioning from baseline to post-tDCS, which was maintained at 2 months. The patient also reported lessened feelings of anger and frustration over social disappointments. Informal follow-up 1 year after stimulation indicates that the patient continues to maintain many improvements.


Anodal tDCS to the rTPJ may represent an effective treatment for improving social functioning in ASD, with a larger clinical trial needed to validate this effect.

Conclusions—This study provides the first evidence that VNS paired with rehabilitative training after stroke (1) doubles long-lasting recovery on a complex task involving forelimb supination, (2) doubles recovery on a simple motor task that was not paired with VNS, and (3) enhances structural plasticity in motor networks.

Scientific Explanation of VNS Paired Stimulation for Tinnitus and Stroke Rehabilitation

Each time the vagus nerve is stimulated, it sends a signal up to the brain, which triggers the release of neurotransmitters (acetylcholine and norepinephrine)   broadly across the brain thus enabling neuroplasticity. In effect it is telling the brain to pay attention to the task at hand.
In someone having therapy after a stroke this might be learning to open a jar, but in autism it might be speech therapy.

The image below illustrates the therapy in action. While the patient is performing a rehabilitative exercise, the physical therapist pushes a button, which triggers the wireless transmitter to send a signal to the implanted device to deliver a small burst of electrical stimulation to the vagus nerve.

big clinical trial:-

It does seem that using electricity in one way or another does have some therapeutic effect in some people with autism. The reason it may be effective in some people is not always entirely clear.
Personally, I like the idea of tVNS to potentially give a learning boost during 1:1 therapy to struggling learners with autism, just as VNS is being used in elderly people who have lost function in their limbs after a stroke and need to relearn how to control their muscles.
It appears that the amount of electricity used in stroke patients is much lower (one 60th) than in those with epilepsy. Perhaps it will be possible to develop a tVNS therapy that does cause any discomfort in the patient’s ear.  
Nobody is researching transcutaneous vagal nerve stimulation for improved learning in autism, given that some doctors at leading hospitals like Johns Hopkins do seem to like zapping people with autism, perhaps somebody should. There looks to be more science behind this than some other shock treatments, which do look quite crude, but do seem to help some people.  

Parkinson’s Disease and the Vagal Nerve
We saw in an earlier post that what goes on in the gut is communicated to the brain, bypassing the blood brain barrier, via the vagal nerve.  In that post it was mice who had their vagal nerve severed in the name of science.
Until recently a common therapy in humans with peptic ulcers was to severe the vagal nerve.  It turns out that these people are protected from developing Parkinson’s Disease. Interesting?

Wednesday, 4 October 2017

Sodium Benzoate and GABRA5 - Raising Cognitive Function in Autism

I am still looking for additional cognitive enhancing autism therapies. It seems the best way to find them may actually be to reread my own blog.
A long time ago I suggested that Cinnamon could well be therapeutic in autism, most likely (but not entirely) due to the sodium benzoate (NaB) it produces in your body.

Sodium benzoate (NaB) is both a drug used to reduce ammonia in your blood and a common food additive that acts as a preservative.
NaB has many biological effects.  One effect relates to a protein called DJ-1, which is produced by a Parkinson’s gene (PARK7). I had noticed that when the body tries to turn on its anti-oxidant genes after the switch Nrf2 is activated, the process cannot proceed without enough DJ-1.  This is why Peter Barnes, from my Dean’s list, suggested that patients with COPD might benefit from more DJ-1.  COPD is a kind of severe asthma which occurs with severe oxidative stress, the oxidative stress stops the standard asthma drugs from working, which is why so many people die from COPD. Oxidative stress is a key feature of most autism.
To make more DJ-1 you can use sodium benzoate (NaB) which is produced gradually in the body if you eat cinnamon. So in theory cinnamon is like sustained release NaB, it is also extremely cheap.
Independently of all this NaB has been trialled in schizophrenia and a further larger trial is in progress.  Autism is not schizophrenia, but the hundreds of genes miss-expressed in autism do overlap with the hundreds of genes miss-expressed in schizophrenia, so I call schizophrenia autism’s big brother. 

GABAA α5 subunit
The scientist readers of this blog may recall that there are two sub-units of the GABAA receptor that I am seeking to modify, to improve cognition.  One is the α3 subunit and the other is the α5 subunit. Low dose clonazepam works for α3.
The α5 subunit is the target of a new drug to improve cognition in people with Down Syndrome (DS).
Very recent research links the same sub-unit to autism, so it is not just me looking at this.

Reduced expression of α5GABAA receptors elicits autism-like alterations in EEG patterns and sleep-wake behavior                                                                                                              

As is often the case, it looks like some people might need to “turn up the volume” from α5GABAA receptors and others might need to turn it down.
I had yet to find a practical way to affect α5GABAA. Now I have realized that I have already stumbled upon such a way to do it.
Pahan, a researcher in Chicago, has shown that he can improve cognition in mice using cinnamon. He noted that in poor learners GABRA5 was elevated, but that after one month of cinnamon GABRA5 was normalized. 

Cognitive loss in autism, schizophrenia and Down Syndrome
Most people might associate MR/ID with autism and indeed Down Syndrome; you likely do not really consider people with schizophrenia to have MR/ID. In reality, cognitive loss is a common feature/problem in schizophrenia and indeed bipolar, just not enough to be called MR/ID.
Those researching schizophrenia seem to focus on NMDA receptors, whereas my blog only goes into the great depths of science when it comes to GABAA . To the schizophrenia researchers NaB is interesting because it is a d-amino acid oxidase inhibitor, which means that it will enhance NMDA function.  So if you are one of those people with too little NDMA activity (NMDAR hypofunction) then sodium benzoate should make you feel better.
The schizophrenia researchers think NaB is helpful because of its effect on NMDA, for me it is GABRA5 that is of great interest. The same should be true for parents of kids with Down Syndrome (DS). We have seen that bumetanide should, and indeed does, help DS.  It looks to me that NaB/Cinnamon should further help them and no need to wait for Roche to commercialize their GABRA5 drug. 

NaB and Cinnamon
I am yet to determine how much NaB is produced by say 3g of cinnamon.
The clinical trials of NaB use 1g per day in adults. People using cinnamon, like Dr Pahan, for cognition or just lowing blood pressure and blood sugar use around 3g.
It is quite difficult to give a teaspoonful of cinnamon to a child, whereas NaB dissolves in water and does not taste so bad. 

NaB and Cinnamon Trials
I did trial cinnamon by putting it in in large gelatin capsules and at the time I did think it had an effect, but I doubt I got close to Dr Pahan’s dosage.
A prudent dose of NaB would seem to be 6mg/Kg twice a day. This is similar to what is now being trialed in schizophrenia.
A small number of people do not tolerate NaB and logically also cinnamon.  They are DAAO inhibitors, just like Risperidone. People who are histamine intolerant need to avoid DAAO inhibitors. If you have allergies it does not mean you are histamine intolerant.
I did try NaB on myself and I did not notice any effect.

I had already obtained some NaB to follow up on my earlier trial of cinnamon.  Having read about the effect of NaB on GABRA5 expression, I am even more curious to see if it helps.
Any positive effect might be due to DJ-1 boosting the effect of Nrf-2, it might be boosting NMDA or it might be reducing GABRA5 expression. In some people all three would be useful.

Press release:- 

Pahan a researcher at Rush University and the Jesse Brown VA Medical Center in Chicago, has found that cinnamon turns poor learners into good ones—among mice, that is. He hopes the same will hold true for people.

His group published their latest findings online June 24, 2016, in the Journal of Neuroimmune Pharmacology.

"The increase in learning in poor-learning mice after cinnamon treatment was significant," says Pahan. "For example, poor-learning mice took about 150 seconds to find the right hole in the Barnes maze test. On the other hand, after one month of cinnamon treatment, poor-learning mice were finding the right hole within 60 seconds."

Pahan's research shows that the effect appears to be due mainly to sodium benzoate—a chemical produced as cinnamon is broken down in the body.

In their study, Pahan's group first tested mice in mazes to separate the good and poor learners. Good learners made fewer wrong turns and took less time to find food. 

In analyzing baseline disparities between the good and poor learners, Pahan's team found differences in two brain proteins. The gap was all but erased when cinnamon was given. 

"Little is known about the changes that occur in the brains of poor learners," says Pahan. "We saw increases in GABRA5 and a decrease in CREB in the hippocampus of poor learners. Interestingly, these particular changes were reversed by one month of cinnamon treatment." 

The researchers also examined brain cells taken from the mice. They found that sodium benzoate enhanced the structural integrity of the cells—namely in the dendrites, the tree-like extensions of neurons that enable them to communicate with other brain cells

As for himself, Pahan isn't waiting for clinical trials. He takes about a teaspoonful—about 3.5 grams—of cinnamon powder mixed with honey as a supplement every night.  
Should the research on cinnamon continue to move forward, he envisions a similar remedy being adopted by struggling students worldwide. 

The paper itself:- 

This study underlines the importance of cinnamon, a commonly used natural spice and flavoring material, and its metabolite sodium benzoate (NaB) in converting poor learning mice to good learning ones. NaB, but not sodium formate, was found to upregulate plasticity-related molecules, stimulate NMDA- and AMPA-sensitive calcium influx and increase of spine density in cultured hippocampal neurons. NaB induced the activation of CREB in hippocampal neurons via protein kinase A (PKA), which was responsible for the upregulation of plasticity-related molecules. Finally, spatial memory consolidation-induced activation of CREB and expression of different plasticity-related molecules were less in the hippocampus of poor learning mice as compared to good learning ones. However, oral treatment of cinnamon and NaB increased spatial memory consolidation-induced activation of CREB and expression of plasticity-related molecules in the hippocampus of poor-learning mice and converted poor learners into good learners. These results describe a novel property of cinnamon in switching poor learners to good learners via stimulating hippocampal plasticity. 

We have seen that cinnamon and NaB modify T cells and protect mice from experimental allergic encephalomyelitis, an animal model of multiple sclerosis. Cinnamon and NaB also upregulate neuroprotective molecules (Parkin and DJ-1) and protect dopaminergic neurons in MPTP mouse model of Parkinson’s disease.  Recently, we have seen that cinnamon and NaB attenuate the activation of p21ras, reduce the formation of reactive oxygen species and protect memory and learning in 5XFAD model of AD. Here we delineate that NaB is also capable of improving plasticity in cultured hippocampal neurons. Our conclusion is based on the following: First, NaB upregulated the expression of a number of plasticity-associated molecules (NR2A, GluR1, Arc, and PSD95) in hippocampal neurons. Second, Gabra5 is known to support long-term depression. It is interesting to see that NaB did not stimulate the expression of Gabra5 in hippocampal neurons. Third, NaB increased the number, size and maturation of dendritic spines in cultured hippocampal neurons, suggesting a beneficial role of NaB in regulating the synaptic efficacy of neurons. Fourth, we observed that NaB did not alter the calcium dependent excitability of hippocampal neurons, but rather stimulated inbound calcium currents in these neurons through ionotropic glutamate receptor. Together, these results clearly demonstrate that NaB is capable of increasing neuronal plasticity.

These results suggest that NaB and cinnamon should not cause health problems and that these compounds may have prospects in boosting plasticity in poor learners and in dementia patients. In summary, we have demonstrated that cinnamon metabolite NaB upregulates plasticity-associated molecules and calcium influx in cultured hippocampal neurons via activation of CREB. While spatial memory consolidation-induced activation of CREB and expression of plasticity-related molecules were less in the hippocampus of poor learning mice as compared to good learning ones, oral administration of cinnamon and NaB increased memory consolidation-induced activation of CREB and expression of plasticity-related molecules in vivo in the hippocampus of poor learning mice and improved their memory and learning almost to the level that observed in untreated good learning ones. These results highlight a novel plasticity-boosting property of cinnamon and its metabolite NaB and suggest that this widely-used spice and/or NaB may be explored for stimulating synaptic plasticity and performance in poor learners.

The schizophrenia trials:-

Plenty of people with schizophrenia now self-treat with NaB; just look on google.

There is now is a small trial in autism:-

A Pilot Trial of Sodium Benzoate, a D-Amino Acid Oxidase Inhibitor, Added on Augmentative and Alternative Communication Intervention for Non-Communicative Children with Autism Spectrum Disorders

Results: We noted improvement of communication in half of the children on benzoate. An activation effect was reported by caregivers in three of the six children, and was corroborated by clinician’s observation. Conclusion: Though the data are too preliminary to draw any definite conclusions about efficacy, they do suggest this therapy to be safe, and worthy of a double-blind placebo-controlled study with more children participated for clarification of its efficacy.

Sunday, 26 February 2017

Secondary Monoamine Neurotransmitter Disorders in Autism – Treatment with 5-HTP and levodopa/carbidopa?

This post is about monoamine neurotransmitter disorders in Autism, that are usually a down-stream consequence of other miscellaneous dysfunctions, which makes them “secondary” dysfunctions.

There was a post on this blog way back in 2013 on catecholamines:

Classical monoamine is a broader term and encompasses:-

       ·          Classical Tryptamines:

Drugs used to increase or reduce the effect of monoamines are sometimes used to treat patients with psychiatric disorders, including depression, anxiety, and schizophrenia.

This blog does go on rather ad nauseam about histamine, so today it will skip over it.  It does not cause autism, but it certainly can make it much worse in some people.

Tryptophan is a precursor to the neurotransmitters serotonin and melatonin.  For years it has been known that odd things are going on in some people with autism regarding tryptophan, serotonin and indeed melatonin. This research does not really lead you anywhere.

Other than being converted to serotonin and melatonin, tryptophan has the potential to be converted in the gut into some very good things and some bad ones; this all depends on what bacteria are present. People lucky enough to have Clostridium sporogenes will produce a super potent, but apparently very safe, antioxidant called 3-Indolepropionic acid (IPA), which is seen as an Alzheimer’s  therapy.  To be effective you would need a constant supply of IPA, and that is exactly what you get from the right bacteria living in your gut.

Some people with autism have high levels of serotonin in their blood and so do their parent(s). It is known that in the brain many people with autism have low levels of serotonin.  Various mechanisms have been proposed to explain this using the body’s feedback loops, including mother to child.

Many people with autism take 5-HTP which is an  intermediate in the synthesis of both serotonin and melatonin from tryptophan.

Serotonin itself does not cross the blood brain barrier (BBB).

Too much serotonin in your brain has a negative effect and so taking too much 5-HTP supplement produces negative effects.

Many people take melatonin at small doses for sleep. At larger doses it has many other beneficial effects that range from resolving GI problems to reducing oxidative stress in mitochondria. 

Of the Catecholamines, it is dopamine that gets the most attention in neuro-psychiatric disorders and schizophrenia in particular.

There is a dopamine hypothesis for schizophrenia, but there is also a glutamate hypothesis of schizophrenia. 

If you read the research, it is actually ADHD that has the strongest connection to dopamine.  When you look closer still, you will see that even that connection is quite weak.

The conclusion is that ADHD, just like autism and schizophrenia is usually multigenic, meaning that numerous little things went awry, rather than one single dysfunction.

Tourette's syndrome and related tic disorders may be associated with either too much dopamine or overly sensitive dopamine receptors. 

It is fair to say that secondary monoamine neurotransmitter disorders can occur in autism, ADHD and indeed schizophrenia.

There is a long list of primary monoamine neurotransmitter disorders and much is known about them.

Monoamine Neurotransmitter Disorders  

I found an excellent paper that tells you pretty much all you could want to know about monoamine neurotransmitter disorders.  It also has nice graphics to explain what is going on.

Most people with autism are unlikely to have a primary disorder, but if they did, treating it should have a big impact on them.

BH4 =tetrahydrobiopterin. TH-D=tyrosine hydroxylase deficiency. AADC-D=aromatic L-amino acid decarboxylase deficiency. DTDS=dopamine transporter deficiency syndrome. PLP-DE=pyridoxal-phosphate-dependent epilepsy. P-DE=pyridoxine-dependent epilepsy. AD GTPCH-D=autosomal dominant GTP cyclohydrolase 1 deficiency. SR-D=sepiapterin reductase deficiency. AR GTPCH-D=autosomal recessive GTP cyclohydrolase 1 deficiency. PTPS-D=6-pyruvoyltetrahydropterin synthase deficiency. DHPR-D=dihydropteridine reductase deficiency. HIE=hypoxic ischaemic encephalopathy. PKAN=pantothenate kinase associated neurodegeneration. DNRD=dopa non-responsive dystonia. PKD=paroxysmal kinesogenic dyskinesia.

People with a secondary disorder would typically be identified by testing their spinal fluid for the metabolites of the monoamine.  So for serotonin you measure  5-HIAA (5-hydroxyindoleacetic acid) and for dopamine you measure  HVA (homovanillic acid).

Figure 2: The monoamine neurotransmitter biosynthesis pathway BH4 is synthesized in four enzymatic steps from GTP. BH4 is a necessary cofactor for TrpH and TH, the rate limiting enzymes in monoamine synthesis. Tryptophan is converted to 5-HTP by TrpH. Tyrosine is converted to L-dopa by TH. The conversion of 5-HTP to serotonin and of L-dopa to dopamine is catalyzed by AADC and its cofactor PLP.  When BH4 acts as a cofactor for TH and TrpH, it is converted to PCBD, which in turn is converted to BH4 (in the BH4 regeneration pathway) by a two-step process involving PCD and DHPR. After synthesis, uptake of monoamine neurotransmitters into the synaptic secretory vesicles requires the vesicular monoamine transporter VMAT (not shown).⁶ After synaptic transmission, serotonin and dopamine are metabolised through similar pathways, which involve MAO enzymes and COMT. Presynaptic reuptake of the monoamines is facilitated by DAT and SERT (not shown).⁷ Metabolic pathway of BH4 synthesis is shown in light blue, monoamine synthesis in light green, monoamine catabolism in dark blue, and BH4 regeneration in red. The biogenic amines are illustrated in light green circles and the cofactors (BH4 and PLP) are represented by light blue circles. Enzymes in the monoamine neurotransmitter pathway are underlined. GTPCH=GTP cyclohydrolase 1. H₂NP₃=dihydroneopterin triphosphate. PTPS=6-pyruvoyltetrahydropterin synthase. 6-PTP=6-pyruvoyltetrahydropterin. AR=aldose reductase. SP=sepiapterin. SR=sepiapterin reductase. BH4 =tetrahydrobiopterin. TrpH=tryptophan hydroxylase. TH=tyrosine hydroxylase. DHPR=dihydropteridine reductase. PCBD=tetrahydrobiopterin-α-carbinolamine. PCD=pterin-4αcarbinolamine dehydratase. qBH₂=(quinonoid) dihydrobiopterin. 5-HTP=5-hydroxytryptophan. L-dopa=levodihydroxyphenylalanine. COMT=catechol-O-methyltransferase. 3-OMD=3-ortho-methyldopa. VLA=vanillactic acid. AADC=aromatic L-amino acid decarboxylase. PLP=pyridoxal phosphate. DBH=dopamine β hydroxylase. PNMT=phenylethanolamine N-methyltransferase. MAO=monoamine oxidase. AD=aldehyde dehydrogenase. 3-MT=3-methoxytyramine. DOPAC=3,4-dihydroxyphenylacetic acid. 5-HIAA=5-hydroxyindoleacetic acid. HVA=homovanillic acid. MHPG=3-methoxy-4-hydroxylphenylglycol. VMA=vanillylmandelic acid.

The paper is very clear about what to:-

Secondary neurotransmitter disorders

Neurotransmitters abnormalities indicative of dopamine or serotonin depletion are becoming increasingly recognized as secondary phenomena in several neurological disorders. Concentrations of HVA and 5-HIAA in CSF in such patients are mostly within the range deemed abnormal for primary neurotransmitter disorders, but generally do not reach the lowest levels.

A secondary reduction in HVA is reported in perinatal asphyxia, disorders of folate metabolism, phenyl ketonuria, Lesch-Nyhan disease, mitochondrial disorders, epilepsy (and infantile spasms), opsoclonus-myoclonus, pontocerebellar hypoplasia, leukodystrophies, Rett’s syndrome, and some neuropsychiatric disorders.  Many patients who have no specific diagnosis but who present with neuromuscular or dystonic symptoms have low HVA concentrations in CSF, which suggests dopaminergic depletion. These patients also often present with dyskinesia, tremor, and eye-movement disorders similar to those seen in many of the primary monoamine neurotransmitter disorders. Cortical atrophy is associated with low levels of 5-HIAA in CSF. Low concentrations of HVA and 5-HIAA have been reported in patients with type 2 pontocerebellar hypoplasia and in a syndrome that involves spontaneous periodic hypothermia and hyperhidrosis.  Whether the latter syndrome is a primary or secondary neurotransmitter disorder is still unclear because the underlying cause is unknown. Patients with neonatal disease onset who have severe motor deficits and abnormalities on brain MRI seem particularly vulnerable to secondary reductions in HVA production. Such disruption of normal brain function is likely to impair biogenic monoamine synthesis, and the resultant neurotransmitter deficiencies in critical periods of neurodevelopment are thought to prevent development of certain brain functions. The possibility of treating such patients with levodopa, 5-hydroxytryptophan, or both should be considered, therefore, to improve brain maturation and neurological outcome.

When you look at autism specifically it is usually 5-HIAA and not HVA that is disturbed.  

Now for two papers by one of our reader Roger’s favourite researchers, Vincent Ramaekers. Ramaekers is one of the specialists for central folate deficiency and even better is a researcher/clinician who replies to my emails. 


Patients with autism spectrum disorder (ASD) may have low brain serotonin concentrations as reflected by the serotonin end-metabolite 5-hydroxyindolacetic acid (5HIAA) in cerebrospinal fluid (CSF).


We sequenced the candidate genes SLC6A4 (SERT), SLC29A4 (PMAT), and GCHFR (GFRP), followed by whole exome analysis.


The known heterozygous p.Gly56Ala mutation in the SLC6A4 gene was equally found in the ASD and control populations. Using a genetic candidate gene approach, we identified, in 8 patients of a cohort of 248 with ASD, a high prevalence (3.2%) of three novel heterozygous non-synonymous mutations within the SLC29A4 plasma membrane monoamine transporter (PMAT) gene, c.86A > G (p.Asp29Gly) in two patients, c.412G > A (p.Ala138Thr) in five patients, and c.978 T > G (p.Asp326Glu) in one patient. Genome analysis of unaffected parents confirmed that these PMAT mutations were not de novo but inherited mutations.

Expression of mutations PMAT-p.Ala138Thr and p.Asp326Glu in cellulae revealed significant reduced transport uptake activity towards a variety of substrates including serotonin, dopamine, and 1-methyl-4-phenylpyridinium (MPP+), while mutation p.Asp29Gly had reduced transport activity only towards MPP+. At least two ASD subjects with either the PMAT-Ala138Thr or the PMAT-Asp326Glu mutation with altered serotonin transport activity had, besides low 5HIAA in CSF, elevated serotonin levels in blood and platelets. Moreover, whole exome sequencing revealed additional alterations in these two ASD patients in mainly serotonin-homeostasis genes compared to their non-affected family members.


Our findings link mutations in SLC29A4 to the ASD population although not invariably to low brain serotonin. PMAT dysfunction is speculated to raise serotonin prenatally, exerting a negative feedback inhibition through serotonin receptors on development of serotonin networks and local serotonin synthesis. Exome sequencing of serotonin homeostasis genes in two families illustrated more insight in aberrant serotonin signaling in ASD.

In this context, we found that isolated low brain serotonin concentration, as reflected by the 5HIAA in the CSF, is associated with PDD-NOS and the functional (heterozygous) c.167G > C (p.G56A) mutation of the serotonin re-uptake transporter gene (SERT/SCL6A4) combined with a homozygous long (L/L) SERT gene-linked polymorphic promoter (5-HTTLPR) region [21]. Moreover, daily treatment with serotonin precursor 5-hydroxytryptophan and aromatic amino acid decarboxylase (AADC) inhibitor carbidopaled to clinical improvements and normalization of the 5HIAA levels in the CSF and urine, indicating that the brain serotonin turnover was normalized [22]. In an attempt to gain some insight into the brain serotonin physiology and underlying mechanisms of abnormal brain metabolism, we report in patients with ASD and low brain 5HIAA mutations in the serotonin transporter SCL29A4, an observation that may provide some bases for improving the application of various therapeutic tools.

Whole blood serotonin and platelet serotonin content are increased in about 25 to 30% of the ASD population and their first-degree relatives. Because the fetal blood–brain barrier during pregnancy is not yet fully formed, the fetal brain will be exposed to high serotonin levels, leading through a negative-feedback mechanism to a loss of serotonin neurons and a limited outgrowth of their terminals. This hypothesis has been confirmed by rat studies using the serotonin agonist 5-methoxytryptamine between gestational days 12 until postnatal day 20 [42].

Tryptophan hydroxylase (TPH; EC catalyzes the first rate-limiting step of serotonin biosynthesis by converting l-tryptophan to 5-hydroxytryptophan. Serotonin controls multiple vegetative functions and modulates sensory and alpha-motor neurons at the spinal level. We report on five boys with floppiness in infancy followed by motor delay, development of a hypotonic-ataxic syndrome, learning disability, and short attention span. Cerebrospinal fluid (CSF) analysis showed a 51 to 65% reduction of the serotonin end-metabolite 5-hydroxyindoleacetic acid (5HIAA) compared to age-matched median values. In one out of five patients a low CSF 5-methyltetrahydrofolate (MTHF) was present probably due to the common C677T heterozygous mutation of the methylenetetrahydrofolate reductase (MTHFR) gene. Baseline 24-h urinary excretion showed diminished 5HIAA values, not changing after a single oral load with l-tryptophan (50-70 mg/kg), but normalizing after 5-hydroxytryptophan administration (1 mg/kg). Treatment with 5-hydroxytryptophan (4-6 mg/kg) and carbidopa (0.5-1.0 mg/kg) resulted in clinical amelioration and normalization of 5HIAA levels in CSF and urine. In the patient with additional MTHFR heterozygosity, a heterozygous missense mutation within exon 6 (G529A) of the TPH gene caused an exchange of valine by isoleucine at codon 177 (V177I). This has been interpreted as a rare DNA variant because the pedigree analysis did not provide any genotype-phenotype correlation. In the other four patients the TPH gene analysis was normal. In conclusion, this new neurodevelopmental syndrome responsive to treatment with 5-hydroxytryptophan and carbidopa might result from an overall reduced capacity of serotonin production due to a TPH gene regulatory defect, unknown factors inactivating the TPH enzyme, or selective loss of serotonergic neurons.

Carbidopa is a drug given to people with Parkinson's disease in order to inhibit peripheral metabolism of levodopa. This property is significant in that it allows a greater proportion of peripheral levodopa to cross the blood–brain barrier for central nervous system effect.

L-DOPA/levodopa is the precursor to the neurotransmitters dopamine, norepinephrine (noradrenaline), and epinephrine (adrenaline) collectively known as catecholamines. Furthermore, L-DOPA itself mediates neurotrophic factor release by the brain and CNS. As a drug, it is used in the clinical treatment of Parkinson's disease.


Based upon the hypothesis that brain monoamine metabolism is disorganized in some children with an autistic disorder, we tried low dose levodopa therapy (0.5 mg/kg/day) proposed by Segawa, et al. We treated 20 patients with an autistic disorder diagnosed according to DSM-IV, and evaluated the effectiveness. A double blind cross over method was applied in this study because of the small number of patients. Drug effects were observed carefully by the psychologists and pediatric neurologists using an evaluation sheet consisting of twenty items. No significant effectiveness was observed in this study, although four cases (20%) showed some improvement. In conclusion, administration of low dose levodopa to autistic children resulted in no clear clinical improvements of autistic symptoms.

A team led by Wen-Hann Tan,  of the Genetics Program at Children’s, is completing a phase I clinical trial examining the safety and dosing of levodopa, a drug commonly used for Parkinson disease, in patients with Angelman syndrome. The results will inform a planned phase II treatment trial, to be conducted in collaboration with University of California San Francisco, University of California San Diego, Vanderbilt University, Baylor College of Medicine and Greenwood Genetic Center. [For more information on Angelman research and events, check out this Facebook page.]

Research suggests that levodopa may increase the activity of an important brain enzyme known as CaMKII, which is involved in learning and memory, and that may be decreased in Angelman syndrome. In a mouse model of Angelman syndrome, low activity of CaMKII is associated with neurologic defects. Levodopa reverses the chemical modification that underlies decreased CaMKII activity. When this same modification is reversed in mice by genetic means, they show improvement in neurologic deficits, and it’s hoped that levodopa can do the same in humans.

Parkinson's disease

We saw in an earlier post that people with Down Syndrome are prone to early onset Alzheimer’s. In the case of lack of dopamine the risk might be towards Parkinson's disease (PD). 

There was a recent post on PANS/PANDAS/Tourette’s which like PD results from dysfunction in the basal ganglia region of the brain.

The basal ganglia, a group of brain structures innervated by the dopaminergic system, are the most seriously affected brain areas in PD. The main pathological characteristic of PD is cell death in the substantia nigra, where greatly reduced activity of dopamine-secreting cells caused by cell death.

When a decision is made to perform a particular action, inhibition is reduced for the required motor system, thereby releasing it for activation. Dopamine acts to facilitate this release of inhibition, so high levels of dopamine function tend to promote motor activity, while low levels of dopamine function, such as occur in PD, demand greater exertions of effort for any given movement. Thus, the net effect of dopamine depletion is to produce hypokinesia, an overall reduction in motor output. Drugs that are used to treat PD, conversely, may produce excessive dopamine activity, allowing motor systems to be activated at inappropriate times and thereby producing dyskinesias.

The drugs used in PD only treat some of the symptoms and are not curative, but do offer effective ways to increase dopamine levels.

High rates of Parkinsonism in adults with autism? Or is it partly drug-induced Parkinsonism

There is a study suggesting high rates of Parkinsonism in adults with autism.  I think some of this is more likely to be drug-induced Parkinsonism, either caused by currently taken drugs, or those taken in earlier years, which is not mentioned in the study. 


While it is now recognized that autism spectrum disorder (ASD) is typically a life-long condition, there exist only a handful of systematic studies on middle-aged and older adults with this condition.

We first performed a structured examination of parkinsonian motor signs in a hypothesis-generating, pilot study (study I) of 19 adults with ASD over 49 years of age. Observing high rates of parkinsonism in those off atypical neuroleptics (2/12, 17 %) in comparison to published population rates for Parkinson’s disease and parkinsonism, we examined a second sample of 37 adults with ASD, over 39 years of age, using a structured neurological assessment for parkinsonism.
Twelve of the 37 subjects (32 %) met the diagnostic criteria for parkinsonism; however, of these, 29 subjects were on atypical neuroleptics, complicating interpretation of the findings. Two of eight (25 %) subjects not taking atypical neuroleptic medications met the criteria for parkinsonism. Combining subjects who were not currently taking atypical neuroleptic medications, across both studies, we conservatively classified 4/20 (20 %) with parkinsonism.
We find a high frequency of parkinsonism among ASD individuals older than 39 years. If high rates of parkinsonism and potentially Parkinson’s disease are confirmed in subsequent studies of ASD, this observation has important implications for understanding the neurobiology of autism and treatment of manifestations in older adults. Given the prevalence of autism in school-age children, the recognition of its life-long natural history, and the recognition of the aging of western societies, these findings also support the importance of further systematic study of other aspects of older adults with autism.

Drug induced Parkinsonism

Any drug that blocks the action of dopamine (referred to as a dopamine antagonist) is likely to cause parkinsonism. Drugs used to treat schizophrenia and other psychotic disorders such as behaviour disturbances in people with dementia, known as neuroleptic drugs, are possibly the major cause of drug-induced parkinsonism worldwide. Parkinsonism can occur from the use of any of the various classes of neuroleptics.
The atypical neuroleptics – clozapine (Clozaril) and quetiapine (Seroquel), and to a lesser extent olanzapine (Zyprexa) and risperidone (Risperdal) – appear to have a lower incidence of extrapyramidal side effects, including parkinsonism. These drugs are generally best avoided by people with Parkinson’s, although some may be used by specialists to treat symptoms such as hallucinations occurring with Parkinson’s.
For people with Parkinson’s, anti-sickness drugs such as domperidone (Motilium) or ondansetron (Zofran) are the drugs of choice for nausea and vomiting.
As well as neuroleptics, some other drugs can cause drug-induced parkinsonism. These include some medications for dizziness and nausea such as prochlorperazine (Stemetil); and metoclopromide (Maxalon), which is used to stop sickness and in the treatment of indigestion.
Calcium channel blocking drugs used to treat high blood pressure, abnormal heart rhythm, angina pectoris, panic attacks, manic depression and migraine may occasionally cause drug-induced parkinsonism. Calcium channel blocking drugs are, however, widely used to treat angina and high blood pressure, and it is important to note that most common agents in clinical use probably do not have this side effect. These drugs should never be stopped abruptly without discussion with your doctor.
A number of other agents have been reported to cause drug-induced parkinsonism, but clear proof of cause and effect is often lacking. Amiodarone, used to treat heart problems, causes tremor and some people have been reported to develop Parkinson’s-like symptoms. Sodium valproate, used to treat epilepsy, and lithium, used in depression, both commonly cause tremor which may be mistaken for Parkinson’s.

Dopamine Receptors vs Dopamine as Dysfunctions 

We saw in great detail with the neurotransmitter GABA that the autism dysfunctions are usually related to the function and make-up of the neurotransmitter receptors, rather than the amount of GABA itself. Targeting these dysfunctions does indeed deliver results for many people with autism and Asperger’s.

Potentially this might be the case with dopamine, but it looks much less likely.

I did look at the following paper which seeks to link the genes of dopamine receptors (DRD1, DRD2, DRD3, DRD4, DRD5), dopamine-synthesizing enzyme DDC, dopamine transporter (DAT) and dopamine-catabolizing enzymes COMT and MAO to the several hundred known autism genes.

Using bioinformatics, in some they found a link and in others they did not.

The graphic below looks nice, but I am not sure it tells us much useful.  To me it looks much better to go direct to the autism gene and then see how to selectively modulate it. I do not think you can assume that the associated dopamine gene/receptor is the unifying problem across dysfunctional autism genes.  It would be great if it was.  

Autism spectrum disorder (ASD) is a debilitating brain illness causing social deficits, delayed development and repetitive behaviors. ASD is a heritable neurodevelopmental disorder with poorly understood and complex etiology. The central dopaminergic system is strongly implicated in ASD pathogenesis.

Genes encoding various elements of this system (including dopamine receptors, the dopamine transporter or enzymes of synthesis and catabolism) have been linked to ASD. Here, we comprehensively evaluate known molecular interactors of dopaminergic genes, and identify their potential molecular partners within up/down-steam signaling pathways associated with dopamine. These in silico analyses allowed us to construct a map of molecular pathways, regulated by dopamine and involved in ASD. Clustering these pathways reveals groups of genes associated with dopamine metabolism, encoding proteins that control dopamine neurotransmission, cytoskeletal processes, synaptic release, Ca2+ signaling, as well as the adenosine, glutamatergic and gamma-aminobutyric systems. Overall, our analyses emphasize the important role of the dopaminergic system in ASD, and implicate several cellular signaling processes in its pathogenesis.

Fig. 3. Reconstruction of biomolecular pathways related to dopaminergic genes associated with ASD (also see Fig. 2 and Table 2 for details). Known biological interactions between protein products of various genes are shown as complexes or denoted by arrows (sharp – activation, dull – inhibition). Proteins encoded by genes associated with ASD are marked with red (other colors are used here for illustration purposes only, to better distinguish visually between multiple different proteins within the dopaminergic pathways). Clustering of proteins into distinct functional groups is shown by dashed lines.

The strongest evidence for the role of dopamine genes in neuropsychiatric disorders is not in schizophrenia or autism, but in ADHD. As you can see in the paper below, even there the association is weak.


Although twin studies demonstrate that ADHD is a highly heritable condition, molecular genetic studies suggest that the genetic architecture of ADHD is complex. The handful of genome-wide scans that have been conducted thus far show divergent findings and are, therefore, not conclusive. Similarly, many of the candidate genes reviewed here (i.e. DBH, MAOA, SLC6A2, TPH-2, SLC6A4, CHRNA4, GRIN2A) are theoretically compelling from a neurobiological systems perspective, but available data are sparse and inconsistent. However, candidate gene studies of ADHD have produced substantial evidence implicating several genes in the etiology of the disorder. The literature published since recent meta-analyses is particularly supportive for a role of the genes coding for DRD4, DRD5, SLC6A3, SNAP-25, and HTR1B in the etiology of ADHD.

Yet, even these associations are small and consistent with the idea that the genetic vulnerability to ADHD is mediated by many genes of small effect.


In the ideal world you would take a sample of spinal fluid and measure 5-HIAA, to look for low brain serotonin and measure HVA for low brain dopamine.

For low serotonin you would give 5-HTP, with Dr Ramaekers suggesting 1mg/kg.

For low dopamine you would give levodopa or carbidopa.

In the real world even blood draws can be problematic so most people will never have their spinal fluid analyzed. Perhaps one day in the future this will be standard practice after an autism diagnosis, with numerous test being run at the same time and justifying this invasive procedure.   Many blood tests tell you little about brain disorders because the blood brain barrier means that the levels outside the brain will be completely different to those inside the brain. Measuring spinal fluid should be a good proxy for inside the brain.

The research suggests that 1mg/kg of 5-HT could have a long term beneficial effect, particularly if given from a very early age, in those with low serotonin in their brains, which is a large group of autism.

There are 5 types of dopamine receptors and in some genetic disorders the receptors’ response can be up/down regulated.  That would trigger a chain reaction with the non dopamine neurotransmitter receptors that are known to interact with that type of dopamine receptor.

There are associations between some autism genes and some dopamine genes, but it looks much more fruitful to target the autism genes themselves.

Avoid drug induced Parkinson’s Disease and other drug induced disorders, by very selective use of drugs.