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Showing posts with label Down Syndrome. Show all posts
Showing posts with label Down Syndrome. Show all posts

Tuesday, 14 May 2019

Making best use of existing NKCC1/2 Blockers in Autism






Azosemide C12H11ClN6O2S2  


Today’s post may be of interest to those already using bumetanide for autism and for those considering doing so.  It does go into the details, because they really do matter and does assume some prior knowledge from earlier posts.

There has been a very thorough new paper published by a group at Johns Hopkins:-
It does cover all the usual issues and raises some points that have not been covered yet in this blog.  One point is treating autism prenatally. This issue was studied twice in rats, and the recent study was sent to me by Dr Ben Ari.  Short term treatment during pregnancy produced a permanent benefit.

Maternal bumetanide treatment prevents the overgrowth in the VPA condition

            
Brief maternal administration of bumetanide before birth restores low neuronal intracellular chloride concentration ([Cl]i) levels, produces an excitatory-to-inhibitory shift in the action of γ-aminobutyric acid (GABA), and attenuates the severity of electrical and behavioral features of ASD (9, 10), suggesting that [Cl]i levels during birth might play an important role in the pathogenesis of ASD (7). Here, the same bumetanide treatment significantly reduced the hippocampal and neocortical volumes of P0 VPA pups, abolishing the volume increase observed during birth in the VPA condition [hippocampus: P0 VPA versus P0 VPA + BUM (P = 0.0116); neocortex: P0 VPA versus P0 VPA + BUM (P = 0.0242); KWD] (Fig. 3B). Maternal bumetanide treatment also shifted the distribution of cerebral volumes from lognormal back to normal in the population of VPA brains, restoring smaller cerebral structure volumes (Fig. 3C). It also decreased the CA3 volume to CTL level after birth, suggesting that the increased growth observed in this region could be mediated by the excitatory actions of GABA (Fig. 3D). Therefore, maternal bumetanide administration prevents the enhanced growth observed in VPA animals during birth.

One issue with Bumetanide is that it affects both:-

·        NKCC2 in your kidneys, causing diuresis
·        NKCC1 in your brain and elsewhere, which is divided into two slightly different forms NKCC1a and NKCC1b

NKCC1 is also expressed in your inner ear where it is necessary for establishing the potassium-rich endolymph that bathes part of the cochlea, an organ necessary for hearing. 

If you block NKCC1 too much you will affect hearing.

Blocking NKCC1 in children and adults is seen as safe but the paper does query what the effect on hearing might be if given prenatally as the ear is developing.

Treating Down Syndrome Prenatally

While treating autism prenatally might seem a bit unlikely, treating Down Syndrome (DS) prenatally certainly is not.  Very often DS is accurately diagnosed before birth creating a valuable treatment window.  In most countries the vast majority of DS prenatal diagnoses lead to termination, but only a small percentage of pregnancies are tested for DS. In some countries such as Ireland a significant number of DS pregnancies are not terminated, these could be treated to reduce the deficits that will otherwise inevitably follow.



The research does suggest that DS is another brain disorder that responds to bumetanide.


Back to autism and NKCC1

This should remind us that a defect in NKCC1 expression will not only cause elevated levels of chloride with in neurons, but will also affect the levels of sodium and potassium with neurons.

There are many ion channel dysfunctions (channelopathies) implicated in autism and elevated levels of sodium and potassium will affect numerous ion channels.  The paper does suggest that the benefit of bumetanide may go beyond modifying the effect of GABA, which is the beneficial mode of action put forward by Dr Ben Ari.
We have seen how hypokalemic sensory overload looks very similar to what often occurs in autism and that autistic sensory overload is reduced by taking an oral potassium supplement.

The paper also reminds us that loop diuretics like bumetanide and furosemide not only reduce inflow of chloride into neurons, but may also reduce the outflow. This is particularly known of furosemide, but also occurs with bumetanide at higher doses.
The chart below shows that the higher the concentration of bumetanide the strong its effect becomes on blocking NKCC1.


But at higher doses there will also be a counter effect of closing the NKCC2 transporter that allows chloride to leave neurons.
At some point a higher dose of bumetanide may have a detrimental effect on trying to lower chloride within neurons.

Since Dr Ben Ari’s objective is to lower chloride levels in neurons  it is important how freely these ions both enter and exit.  The net effect is what matters. (Loop diuretics block NKCC1 that lets chloride enter neurons but also block the KCC2 transporter via which they exit)

Is Bumetanide the optimal existing drug to lower chloride within neurons?  Everyone agrees that it is not, because only a tiny amount crosses into the brain. The paper gives details of the prodrugs like BUM5 that have been looked at previously in this blog; these are modified versions of bumetanide that can better slip across the blood brain barrier and then react in the brain to produce bumetanide itself.  It also highlights the recent research that suggests that Bumetanide may not be the most potent approved drug, it is quite conceivable that another old drug called Azosemide is superior.

The blood brain barrier is the problem, as is often the case.  Bumetanide has a low pH (it is acidic) which hinders its diffusion across the barrier.  Only about 1% passes through.

There is scepticism among researchers that enough bumetanide can cross into the brain to actually do any good.  This is reflected in the review paper.

The paper reminds us of the research showing how you can boost the level of bumetanide in the brain by adding Probenecid, an OAT3 inhibitor.  During World War 2 antibiotics were in short supply and so smaller doses were used, but their effect was boosted by adding Probenecid. By blocking OAT3, certain types of drug like penicillin and bumetanide are excreted at a slower rate and so the net level in blood increases.

The effect of adding Probenecid, or another less potent OAT3 inhibitors, is really no different to just increasing the dose of bumetanide.

The problem with increasing the dose of bumetanide is that via its effect on NKCC2 you cause even more diuresis, until eventually a plateau is reached.

Eventually, drugs selective for NKCC1a and/or NKCC1b will appear.

In the meantime, the prodrug BUM5 looks good. It crosses the BBB much better than bumetanide, but it still affects NKCC2 and so will cause diuresis.  But BUM5 should be better than Bumetanide + Probenecid, or a higher dose of Bumetanide.  BUM5 remains a custom-made research drug, never used in humans.

I must say that what again stands out to me is the old German drug, Azosemide.

In a study previously highlighted in this blog, we saw that Azosemide is 4 times more potent than Bumetanide at blocking NKCC1a and NKCC1b.

Azosemide is more potent than bumetanide and various other loop diuretics to inhibit the sodium-potassium-chloride-cotransporter human variants hNKCC1A and hNKCC1B

Azosemide is used in Japan, where recent research shows it is actually more effective than other diuretics

Azosemide, a Long-acting Loop Diuretic, is Superior to Furosemide in Prevention of Cardiovascular Death in Heart Failure Patients Without Beta-blockade 

As is often the case, Japanese medicine has taken a different course to Western medicine.

Years of safety information has already been accumulated on Azosemide.  It is not an untried research drug. It was brought to market in 1981 in Germany. It is available as Diart in Japan made by Sanwa Kagaku Kenkyusho and as a cheaper generic version by Choseido Pharmaceutical. In South Korea Azosemide is marketed as Uretin.


In any other sector other than medicine, somebody would have thought to check by now if Azosemide is better than Bumetanide.  It is not a matter of patents, Ben-Ari has patented all of the possible drugs, including Azosemide and of course Bumetanide.

So now we move on to Azosemide.



When researchers came to check the potency of the above drugs the results came as a surprise.  It turns out that the old German drug Azosemide is 4 times as potent as bumetanide.






The big question is how does it cross the blood brain barrier.


“The low brain concentrations of bumetanide obtained after systemic administration are thought to result from its high ionization (>99%) at physiological pH and its high plasma protein binding (>95%), which restrict brain entry by passive diffusion, as well as active efflux transport at the blood-brain barrier(BBB). The poor brain penetration of bumetanide is a likely explanation for its controversial efficacy in the treatment of brain diseases

“… azosemide was more potent than any other diuretic, including bumetanide, to inhibit the two NKCC1 variants. The latter finding is particularly interesting because, in contrast to bumetanide, which is a relatively strong acid (pKa = 3.6), azosemide is not acidic (pKa = 7.38), which should favor its tissue distribution by passive diffusion. Lipophilicity (logP) of the two drugs is in the same range (2.38 for azosemide vs. 2.7 for bumetanide). Furthermore, azosemide has a longer duration of action than bumetanide, which results in superior clinical efficacy26 and may be an important advantage for treatment of brain diseases with abnormal cellular chloride homeostasis.”


Dosage equivalents of loop Diuretics


Bumetanide has very high oral bioavailablity, meaning almost all of what you swallow as a pill makes it into your bloodstream.

Furosemide and Azosemide have much lower bioavailability and so higher doses are needed to give the same effect.

Both Furosemide and Bumetanide are short acting, while Azosemide is long acting.

For a drug that needs to cross the blood brain barrier small differences might translate into profoundly different effects.

The limiting factor in all these drugs is their effect on NKCC2 that causes diuresis.

1mg of bumetanide is equivalent to 40mg of furosemide.
2mg of bumetanide is equivalent to 80mg of furosemide.

The standard dose for Azosemide in Japan, where people are smaller than in the West, is 30 mg or 60mg. 

Research suggests that the same concentration of Azosemide is 4x more potent than Bumetanide at blocking NKCC1 transporters, other factors that matter include:-

·        How much of the oral tablet ends up in the bloodstream.
·        How long does it stay in the blood stream
·        How much of the drug actually crosses the blood brain barrier
·        How does the drug bind to the NKCC1 transporters in neurons
·        How rapidly is the drug excreted from the brain
·        What effect is there on the KCC2 transporter that controls the exit of chloride ions from neurons.

All of this comes down to which is more effective in adults with autism 2mg of bumetanide or 60mg of Azosemide.

The side effects, which are mainly diuresis and loss of electrolytes will be similar, but Azosemide is a longer acting drug and so there will be differences. In fact Azosemide is claimed to be less troublesome than Bumetanide in lower potassium levels in your blood.

Conclusion  

The open question is whether generic Azosemide is “better” than generic Bumetanide for treating brain disorders in humans.

I did recently ask Dr Ben-Ari if he is aware of any data on this subject. There is none.

Many millions of dollars/euros are being spent getting Bumetanide approved for autism, so it would be a pity if Azosemide turns out to be better. (Dr Ben Ari’s company Neurochlore wants to develop a new molecule that will cross the blood brain barrier, block NKCC1 and not NKCC2 and so will not cause diuresis).

The hunch of the researchers from Hanover, Germany seems to be that the old German drug Azosemide will be better than Bumetanide.

I wonder if doctors at Johns Hopkins / Kennedy Krieger have started to prescribe bumetanide off-label to their patients with autism.  Their paper shows that they have a very comprehensive knowledge of the subject.


===========

I suggest readers consult the full version of the Johns Hopkins review paper on Bumetanide, it is peppered with links to all the relevant papers.

Bumetanide (BTN or BUM) is a FDA-approved potent loop diuretic (LD) that acts by antagonizing sodium-potassium-chloride (Na-K-Cl) cotransporters, NKCC1 (SLc12a2) and NKCC2. While NKCC1 is expressed both in the CNS and in systemic organs, NKCC2 is kidney-specific. The off-label use of BTN to modulate neuronal transmembrane Clgradients by blocking NKCC1 in the CNS has now been tested as an anti-seizure agent and as an intervention for neurological disorders in pre-clinical studies with varying results. BTN safety and efficacy for its off-label use has also been tested in several clinical trials for neonates, children, adolescents, and adults. It failed to meet efficacy criteria for hypoxic-ischemic encephalopathy (HIE) neonatal seizures. In contrast, positive outcomes in temporal lobe epilepsy (TLE), autism, and schizophrenia trials have been attributed to BTN in studies evaluating its off-label use. NKCC1 is an electroneutral neuronal Climporter and the dominance of NKCC1 function has been proposed as the common pathology for HIE seizures, TLE, autism, and schizophrenia. Therefore, the use of BTN to antagonize neuronal NKCC1 with the goal to lower internal Cl levels and promote GABAergic mediated hyperpolarization has been proposed. In this review, we summarize the data and results for pre-clinical and clinical studies that have tested off-label BTN interventions and report variable outcomes. We also compare the data underlying the developmental expression profile of NKCC1 and KCC2, highlight the limitations of BTN’s brain-availability and consider its actions on non-neuronal cells.

Btn Pro-Drugs and Analogs

To improve BTN accessibility to the brain, pro-drugs with lipophilic and uncharged esters, alcohol and amide analogs have been created. These pro-drugs convert to BTN after gaining access into the brain. There was a significantly higher concentration of ester prodrug, BUM5 (N,N – dimethylaminoethyl ester), in mouse brains compared to the parent BTN (10 mg/kg, IV of BTN and equimolar dose of 13 mg/kg, IV of BUM5) (Töllner et al., 2014). BUM5 stopped seizures in adult animal models where BTN failed to work (Töllner et al., 2014Erker et al., 2016). BUM5 was also less diuretic and showed better brain access when compared to the other prodrugs, BUM1 (ester prodrug), BUM7 (alcohol prodrug) and BUM10 (amide prodrug). BUM5 was reported to be more effective than BTN in altering seizure thresholds in epileptic animals post-SE and post-kindling (Töllner et al., 2014). Furthermore, BUM5 (13 mg/kg, IV) was more efficacious than BTN (10 mg/kg, IV) in promoting the anti-seizure effects of PB, in a maximal electroshock seizure model (Erker et al., 2016). Compared to BUM5 which was an efficacious adjunct to PB in the above mentioned study, BTN was not efficacious when administered as an adjunct (Erker et al., 2016). In addition to seizure thresholds, further studies need to be conducted to assess effects of BUM5 on seizure burdens, ictal events, duration and latencies.
Recently, a benzylamine derivative, bumepamine, has been investigated in pre-clinical models. Since benzylamine derivatives lack the carboxylic group of BTN, it results in lower diuretic activity (Nielsen and Feit, 1978). This prompted Brandt et al. (2018) to explore the proposed lower diuretic activity, higher lipophilicity and lower ionization rate of bumepamine at physiological pH. Since it is known that rodents metabolize BTN quicker than humans, the study used higher doses of 10 mg/kg of bumepamine similar to their previous BTN studies (Olsen, 1977Brandt et al., 2010Töllner et al., 2014). Bumepamine, while only being nominally metabolized to BTN, was more effective than BTN to support anticonvulsant effects of PB in rodent models of epilepsy. This GABAergic response, however, was not due to antagonistic actions on NKCC1; suggesting bumepamine may have an off-target effect, which remains unknown. However, the anticonvulsive effects of bumepamine, in spite of its lack of action on NKCC1, are to be noted. Additionally, in another study by the same group, it was shown that azosemide was 4-times more potent an inhibitor of NKCC1 than BTN, opening additional avenues for better BBB penetration and NKCC1-antagonizing compounds for potential neurological drug discovery (Hampel et al., 2018).

Conclusion


The beneficial effects of BTN reported in cases of autism, schizophrenia and TLE, given its poor-brain bioavailability are intriguing. The mechanisms underlying the effects of BTN, as a neuromodulator for developmental and neuropsychiatric disorders could be multifactorial due to prominent NKCC1 function at neuronal and non-neuronal sites within the CNS. Investigation of the possible off-target and systemic effects of BTN may help further this understanding with the advent of a new generation of brain-accessible BTN analogs.




Thursday, 10 May 2018

Accept Autism or Treat It?


Back in the old days autism was a hidden condition and those affected were usually tucked away in institutions. A trend then slowly developed towards inclusion, with the Individuals with Disabilities Education Act (IDEA) being passed in 1975 in the US.  Other countries have slowly moved in this direction, with France only this year finally following suit.



Having moved on from hiding autism, we then had the new diagnosis of Asperger’s appearing in the 1990s and so autism became a much broader diagnosis. Then followed the idea of awareness and diagnosing adults.
Now we have an ever-growing number of people diagnosed with this “autism” thing, that other people are supposed to be aware of. Is it a disease, a dysfunction, a disability or just a difference?
Most importantly are you supposed to treat it, or just accept it?
I recently watched a BBC documentary where a doctor was the presenter and she was talking about schizophrenia. She said that at medical school she was taught that there are medical problems and there are mental health problems, for some reason she was taught that mental health problems are not just medical problems of the brain. Somehow mental health problems are supposed to be different and not based in biology, where did that idea come from?
The program went on to show that about 8% of schizophrenia appears to be caused by NMDAR antibodies. This is a condition where antibodies attack NMDA receptors in the brain, this causes hallucinations and other symptoms that a psychiatrist would diagnose as schizophrenia.  Rather than treating lifelong with anti-psychotics, the patient needs immunotherapy and can then resume a normal life.
It looks like 30% of modern autism is associated with cognitive impairment leading to a measured IQ of less than 70. This is intellectual disability (ID) to autism parents and mental retardation (MR) to the rest of the world.
The interesting finding in this blog is that some MR/ID is actually treatable. I did suggest to the Bumetanide researchers that they should include measuring IQ in their clinical trials.
I do not see how anyone could object to treating MR/ID, even those parents with Asperger’s who find the idea of treating their child’s severe autism to be repulsive.

Maths, Autism and Hans Asperger
Some people with Asperger’s are brilliant at maths, and I think these are the ones that Hans Asperger was mostly studying in Vienna in the 1940s. Lorna Wing came along in 1981 and then Uta Frith in 1991 and translated into English one of Asperger’s 300 papers, the 1943/4 “Die Autistischen Psychopathen im Kindesalter” and then named autism with no speech delay as Asperger’s Syndrome.
In 1994 the Americans adopted Asperger’s as a diagnosis and then rejected it two decades later in 2013 (DSM5).
In Asperger’s 1943 paper he described Fritz, Harro, Ernst and Hellmuth, who he termed "autistic psychopaths”; all four had high IQs and Asperger called them "little professors" because they could talk about the area of ​​their special interest in detail and often accumulated amazing knowledge.
I think Asperger’s should have been left as the "Little Professor’s Syndrome" (high IQ only).
In 2018 some people have realized that from the mid 1930’s almost all people in high positions in Austria and Germany were implicated in some pretty evil Nazi programs, including killing mentally disabled children. Asperger, being a senior psychiatrist at the University of Vienna, obviously played a role, not wanting to pay a visit to the local Gestapo basement.  He was living in a police state, where people tend to do what they are told.  Unlike most of the University medical faculty he was not a member of the Nazi party.
The particularly evil Austrian psychiatrist was Dr Emil Gelny, who modified an ECT (Electro Convulsive Therapy) device to give his subjects lethal shocks. Having personally killed hundreds of mental patients, after the end of the war he escaped to Baghdad, continued practising as a doctor and lived till he was 71. He was never brought to account and Mossad clearly never paid a visit, so I guess there were no Jewish victims.  His highly publicized use of ECT is one reason why it is little used today, even though it does seem to help certain otherwise untreatable conditions.
What surprised me was that in 1930 (before the rise of Hitler) half of the doctors in Vienna were Jewish and indeed half of the Vienna medical faculty were Jewish. So not so anti-Semitic in 1930.  All these doctors had to leave and so the young Hans Asperger made rapid career progress.
Things were not all rosy elsewhere.
I recently read that in London in the 1950s Jewish doctors struggled to progress within the faculty of medical schools and so some emigrated to the US.
We should also note that the Nazis took their inspiration for eugenics from America, where it backed by well-known names such as the Carnegie Institution and the Rockefeller Foundation. California, which we now might consider very liberal, was the centre for forced sterilization.  Between 1907 and 1963 over 64,000 individuals were forcibly sterilized under eugenic legislation in the United States.
So, I think Asperger deserves a break, he was likely no better or worse than other Austrians, unlike most he did not join the Nazi Party. Wing and Frith (a German) were naïve to name a psychiatric syndrome based on the work of an Austrian written during the Nazi period. I think you would not name a reservation for native Americans after General George Custer. 

Back to Maths
One group of kids with severe autism do have near/distant relatives who have remarkable maths skills but were never diagnosed with anything other than being a bit odd.
Monty, now aged 14 with ASD, had great difficulty with even the most basic maths until the age of 9, so much so that we did not bother to teach it, we focused on literacy.
Five and a half years of drug treatment has produced a boy who is now great at maths, at least in his class of 12 years olds.
Coordinates, no problem; negative numbers, no problem. It still now shocks those who knew him from before.
Today I received a message from Monty’s assistant at school and a photo of his classwork, where he is solving simple equations like
7x - 6 = 15
That is not a complex problem for a typical boy, but at the age of 9, after 5 years of intensive ABA therapy, we were still challenged by the most basic single digit addition.  


Nice neat handwriting


Should you treat autism? 

Pretty obviously I think autism should be treated. I would favour treating all types of genuine disease.
If you can treat it, I’d definitely call it a disease.
I would treat people with Down Syndrome to raise their IQs to improve their quality of life and I would also treat them preventatively to avoid early onset Alzheimer’s, which they are highly likely to develop. By the age of just 40 years old, studies have shown significant levels of amyloid plaques and tau tangles, which will lead to Alzheimer’s type dementia.
If you cannot treat it, then you’re just going to have to accept it.
But how would you know you cannot treat it, if you do not at least try?
Since there are hundreds of types of autism, there is no one-stop treatment shop for autism. For medical advice you should go to see a doctor, but mainstream medicine believes autism is untreatable. Today it is really up to the parents themselves to figure out what, if anything, to do.  Dr Frye might suggest you try Leucovorin, B12 and NAC; some DAN doctor will tell you it is all about candida; another will treat everyone with cod liver oil; another will blame parasites; most will blame vaccines.  One lady will charge you large amounts of money for her genetic tests, baffle you with complicated looking charts and then sell you her supplements by the bucket-load. This blog suggests numerous therapies may be partially effective in specific people, a case for personalized medicine.  My Polypill is what works for my son's autism; it is nice to know it works for some others, but it does not work for all autism, that would never be possible.  
With schizophrenia, you could start by treating that 8% with NMDAR antibodies via a science-based medical therapy; this has got to be a big step forward over psychiatric drugs.
We have gone from aged 9, struggling with: -
5 + 2 =  ?
To aged 14, solving worded maths questions, where you have to create the formula and to neatly solving simple equations like:

7x – 6  =  15                  
In algebra there is no doubt effective treatment wins over acceptance.

There is more to life than algebra, but it looks pretty clear that going through life with an IQ 30+ points less than your potential is a missed opportunity. 

Trivial autism
Many people with mild autism and an IQ much greater than 70 are happy the way they are and do not want treatment. For them autism is not a disability, it is just a difference, so we might call it trivial autism.  Unless years later they commit suicide or hurt other people, then it was not so trivial after all.
Unfortunately, some people with trivial autism will go on to produce children with not so trivial autism.
Then you end up with situation that the adult can block what is in the child’s interest, just like deaf parents who refuse their deaf child to have cochlear implants to gain some sense of hearing. Cochlear implants are only effective when implanted in very young children, so by the time you are old enough to have you own say in the decision, it is too late.  Some deaf parents do not want hearing children – odd but true.
So, I come back to my earlier point better to treat ID/MR, don’t even call it treating autism.
How can the Asperger’s mother then refuse treatment to her son with autism plus MR/ID? She can still be able to celebrate her difference, while he gets a chance to learn to tie his own shoe laces, put his shirt on the right way around and do all kinds of other useful things.


So, focus on the 31% of autism? 





                     
Unfortunately, in the research trials they often exclude severe autism, so they exclude people with epilepsy, people with MR/ID and people will self-injurious behaviour (SIB). The very people who clearly need treatment are excluded from the trials to determine what are effective autism treatments. Rather odd.




Thursday, 9 November 2017

Variable Expression of GABRA5 and Activation of α5 -  a Modifier of Cognitive Function in Autism?


Today’s post sounds complicated. We actually already know that the gene GABRA5, and hence the alpha 5 sub-unit of GABAA receptors, can affect cognition, but we do not know for sure in whom it is relevant.
Most readers of this blog are lay people, as such we tend to be predisposed to the idea that autism is somehow “hardwired”, something that just happened and cannot be reversed. Some of autism is indeed “hardwired”, you cannot take an adult with autism and “re-prune” his synapses, to produce a more elegant robust network in his brain. But much can be done, because many things in the brain are changing all the time, they are not fixed at all. Today’s post is good example.
GABA is the most important inhibitory neurotransmitter in the brain. There are two types of GABA receptor, A and B. These receptors are made up of sub-units. There are many different possible combinations of sub-units to make GABAA receptors. These combinations are not fixed, or “hard-wired”; they vary all the time.
The composition of the GABAA receptor changes its effect. It can change how you feel (anxiety) and it can change you think/learn.
You can actually measure GABRA5 expression in different regions of the brain in a test subject using a PET-CT (Positron Emission Tomography–Computed Tomography) scan and it has been done in some adults with high functioning autism. This machine looks like a big front-leading washing machine, just a bit cleverer. 

our primary hypothesis was that, compared to controls, individuals with ASD have a significant reduction in α5 GABA receptor availability in these areas.
Due to the small sample size, we could not examine possible correlations between GABAA binding and particular symptoms of ASD, age, IQ, or symptoms of comorbidities frequently associated with ASD, such as anxiety disorders, OCD and depression. We were also unable to address the effects of possible neuroanatomical differences between people with ASD and controls, which might lead to partial volume effects in PET studies. However, the modest magnitude of the volumetric differences seen in most studies of high-functioning ASD suggests that it is unlikely that these could fully explain the present findings.

These preliminary results suggest that potentiation of GABAA signaling, especially at GABAA α5-subunit containing receptors, might potentially be a novel therapeutic target for ASD. Unselective GABAA agonists and positive allosteric modulators, such as benzodiazepines, have undesirable features such as abuse potential and tolerance, but more selective modulators might avoid such limitations. Further research should extend this work in a larger sample of ASD individuals. It would also be interesting to use PET with the ligand [11C]Ro15-4513 to measure GABAA in disorders of known etiology characterised by ASD symptoms, such as Fragile X and 15q11-13 duplication
In summary, we present preliminary evidence of reduced GABAA α5 expression in adult males with ASD, consistent with the hypothesis that ASD is characterised by a defect in GABA signaling. 

The prevalence of autism spectrum disorders (ASDs), which affect over 1% of the population, has increased twofold in recent years. Reduced expression of GABAA receptors has been observed in postmortem brain tissue and neuroimaging of individuals with ASDs. We found that deletion of the gene for the α5 subunit of the GABAA receptor caused robust autism-like behaviors in mice, including reduced social contacts and vocalizations. Screening of human exome sequencing data from 396 ASD subjects revealed potential missense mutations in GABRA5 and in RDX, the gene for the α5GABAA receptor-anchoring protein radixin, further supporting a α5GABAA receptor deficiency in ASDs.

The results from the current study suggest that drugs that act as positive allosteric modulators of α5GABAA receptors may ameliorate autism-like behaviors 
  

Too many or too few the α5GABAA receptors or too much/little activity?

Regular readers will know that autism is all about extremes hypo/hyper, macro/micro etc. The same is true with α5GABAA, too few can cause autistic behaviors, but too many can impede learning. You need just the right amount.
The next variable is how well your α5GABAA are behaving, because even if you have an appropriate number of these receptors, you may not have optimal activity from them. Over activity from α5GABAA is likely to have the same effect as having too many of them.
Here it becomes very relevant to many with autism and inflammatory comorbidities, because systemic inflammation has been shown to activate α5GABAA. It has been shown that increased α5GABAA receptor activity contributes to inflammation-induced memory deficits and, by my extension, to inflammation-induced cognitive decline.

α5GABAA Receptors Regulate Inflammation-Induced Impairment of Long-Term Potentiation


Systemic inflammation causes learning and memory deficits through mechanisms that remain poorly understood. Here, we studied the pathogenesis of memory loss associated with inflammation and found that we could reverse memory deficits by pharmacologically inhibiting α5-subunit-containing γ-aminobutyric acid type A (α5GABAA) receptors and deleting the gene associated with the α5 subunit. Acute inflammation reduces long-term potentiation, a synaptic correlate of memory, in hippocampal slices from wild-type mice, and this reduction was reversed by inhibition of α5GABAA receptor function. A tonic inhibitory current generated by α5GABAA receptors in hippocampal neurons was increased by the key proinflammatory cytokine interleukin-1β through a p38 mitogen-activated protein kinase signaling pathway. Interleukin-1β also increased the surface expression of α5GABAA receptors in the hippocampus. Collectively, these results show that α5GABAA receptor activity increases during inflammation and that this increase is critical for inflammation-induced memory deficits.


We saw in an earlier post that overexpression of GABRA5 is found in slow learners and we know that this is a key target of Down Syndrome research, aimed at raising cognitive function.

What can be modified?
It appears that you can modify the expression of GABRA5, which means you can increase/decrease the number of GABAA receptors that contain an α5 subunit.
You can also tune the response of those α5 subunits. You can increase it or decrease it.
Activation of the α5 subunit is thought to be the reason why benzodiazepine drugs  have cognitive (reducing) side effects. By extension, inverse agonists of α5 are seen as likely to be nootropic.
One such drug is LS-193,268  is a nootropic drug invented in 2004 by a team working for Merck, Sharp and Dohme.
A complication is that you do not want to affect the α2 subunit, or you will cause anxiety. So you need a highly selective inverse agonist.
The new Down Syndrome drug, Basmisanil, is just such a selective inverse agonist of α5.
Basmisanil (developmental code names RG-1662, RO5186582) is a highly selective inverse agonist/negative allosteric modulator of α5 subunit-containing GABAA receptors which is under development by Roche for the treatment of cognitive impairment associated with Down syndrome.  As of August 2015, it is in phase II clinical trials for this indication.


A contradiction
As is often the case, there is an apparent contradiction, because on the one hand a negative allosteric modulator should be nootropic in NT people and appears to raise cognition in models of Down Syndrome; but on the other hand results from a recent study suggests that drugs that act as positive allosteric modulators of α5GABAA receptors may ameliorate autism-like behaviors.
So which is it?
Quite likely both are right.
It is exactly as we saw a long while back with NMDAR activity, some people have too much and some have too little. Some respond to an agonist, some to an antagonist and some to neither.
What we can say is that fine-tuning α5GABAA in man and mouse seems a viable option to enhance cognition in those with learning difficulties.
The clever option is probably the positive/negative allosteric modulator route, the one being pursued by big Pharma for Down Syndrome.
I like Dr Pahan’s strategy from this previous post, for poor learners and those with early dementia

to use cinnamon/NaB to reduce GABRA5 expression, which has got to consequently reduce α5GABAA activity.
All of these strategies are crude, because what matters is α5GABAA activity in each part of the brain. This is why changing GABRA5 expression will inevitably have good effects in one area and negative effects in another area. What matter is the net effect, is it good, bad or negligible?
The fact that systemic inflammation increases α5GABAA activity may contribute to the cognitive decline some people with autism experience.
We previously saw how inflammation changes KCC2 expression and hence potentially increases intra cellular chloride, shifting GABA towards excitatory.
Ideally you would avoid systemic inflammation, but in fact all you can do is treat it.
Increasing α5GABAA activity I would see as possible strategy for people with high IQ, but some autistic features.
I think those with learning problems are likely to be the ones wanting less α5GABAA activity.
The people for whom “bumetanide has stopped working” or “NAC has stopped working” are perhaps the ones who have developed systemic inflammation for some reason.  You might only have to measure C-reactive protein (CRP) to prove this.




More reading for those interested:-