Pleiotropy - your new BFF? SGLT2 inhibitors and targeting the NLRP3 inflammasome to target neurological disorders from Autism to ALS and Alzheimer’s

Pleiotropy 

from Greek πλείων pleion, 'more'

and τρόπος tropos, 'way'

 

 

Today’s post introduces a new term – SGLT2.

Depending how old you are, you will be aware of the term BFF – Best Friend Forever.  These days you can have several BFFs, not just one. 

Pleiotropy (play-o-tropy) is a rather nice sounding word that was brought into use in science and medicine by a German geneticist Ludwig Plate in 1910. Pleiotropic effects of a drug are any beneficial secondary effects.

Statins are the classic example. They were developed to lower cholesterol, but many of the positive effects experienced by users have nothing to do with cholesterol, they lower inflammation (and more besides).  It is now thought that inflammation in your arteries triggers a protective layer of cholesterol to be deposited. As the decades pass, this protective layer grows and ends up causing all kinds of problems.

When you repurpose an old drug for a new use, you are taking advantage of its pleiotropic effects.  For readers of this blog pleiotropy is a friend, and quite possibly a BFF.

 

SGLT2

Today we look at repurposing a class of drugs that lowers blood sugar for those with type 2 diabetes to treat a wide range of brain disorders.

We also look at a cheap pain killer that can be used to disrupt an inflammatory pathway key to most brain disorders and even some cancers.

Our reader Eszter did recently highlight a very well written paper about the potential to repurpose SGLT2 inhibitors to treat autism. Eszter knows a lot about neurology, I should point out.

Eszter has previously commented on the interesting overlap between drugs that provide a benefit in Alzheimer’s and those that benefit some autism.  She will likely find the link at the very end of this post of interest.

 

Repurposing SGLT2 Inhibitors for Neurological Disorders: A Focus on the Autism Spectrum Disorder 

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with a substantially increasing incidence rate. It is characterized by repetitive behavior, learning difficulties, deficits in social communication, and interactions. Numerous medications, dietary supplements, and behavioral treatments have been recommended for the management of this condition, however, there is no cure yet. Recent studies have examined the therapeutic potential of the sodium-glucose cotransporter 2 (SGLT2) inhibitors in neurodevelopmental diseases, based on their proved anti-inflammatory effects, such as downregulating the expression of several proteins, including the transforming growth factor beta (TGF-β), interleukin-6 (IL-6), C-reactive protein (CRP), nuclear factor κB (NF-κB), tumor necrosis factor alpha (TNF-α), and the monocyte chemoattractant protein (MCP-1). Furthermore, numerous previous studies revealed the potential of the SGLT2 inhibitors to provide antioxidant effects, due to their ability to reduce the generation of free radicals and upregulating the antioxidant systems, such as glutathione (GSH) and superoxide dismutase (SOD), while crossing the blood brain barrier (BBB). These properties have led to significant improvements in the neurologic outcomes of multiple experimental disease models, including cerebral oxidative stress in diabetes mellitus and ischemic stroke, Alzheimer's disease (AD), Parkinson's disease (PD), and epilepsy. Such diseases have mutual biomarkers with ASD, which potentially could be a link to fill the gap of the literature studying the potential of repurposing the SGLT2 inhibitors' use in ameliorating the symptoms of ASD. This review will look at the impact of the SGLT2 inhibitors on neurodevelopmental disorders on the various models, including humans, rats, and mice, with a focus on the SGLT2 inhibitor canagliflozin. Furthermore, this review will discuss how SGLT2 inhibitors regulate the ASD biomarkers, based on the clinical evidence supporting their functions as antioxidant and anti-inflammatory agents capable of crossing the blood-brain barrier (BBB).

 

Recently I was asked by one researcher reader where is the evidence to support my suggestion that Ponstan (Mefenamic Acid) can enhance cognition.  I was not sure that I would find evidence that relates to actual humans, but I did. This took me back to the time this blog looked into the NLRP3 inflammasome.

Just like the new generation of type 2 diabetes drugs have pleiotropic effects on the brain, so do Fenamate class NSAIDs, specifically Ponstan.

There are four SGLT2 inhibitors approved to treat type 2 diabetes

·        Invokana (canagliflozin)

·        Farxiga (dapagliflozin)

·        Jardiance (empagliflozin)

·        Steglatro (ertugliflozin)

To be effective inside the brain such a drug would need to be small and lipid (fat soluble) enough to get across the blood brain barrier.

If the idea of a diabetes drug helping brain disorders sounds strange, consider what we have already come across in previous posts in this blog.

  

Other Type 2 drugs with pleiotropic effects

 

Metformin

Metformin was discovered exactly 100 years ago, in 1922.  It is not a new drug and it is the world’s most common therapy for type 2 diabetes.

It has been suggested metformin can delay the onset of aging and also the onset and development of Alzheimer’s.

The use of metformin has repeatedly associated with the decreased risk of the occurrence of various types of cancers, especially of the pancreas and colon and hepatocellular carcinoma.

Metformin has been shown to raise IQ in children with Fragile-X syndrome by about 10%.

Some people with autism do take metformin, in others it provides no benefit.

 

Glitazones

Glitazones are a class of anti-diabetic drug that started to get popular from the year 2000. They  work by stimulating  peroxisome proliferator-activated receptor gamma (PPAR-γ) receptor. They will activate PGC-1 alpha, which we know is the key regulator of mitochondrial biogenesis. For some strange reason, glitazone drugs are not used to treat mitochondrial disease.

Glitazones have broad anti-inflammatory pleiotropic effects.

Pioglitazone has been researched in autism and I have used it for several years as a spring and summertime add-on therapy in Monty’s PolyPill.

 

Back to Eszter’s paper

 

I highlight some of the tables, which do summarize the beneficial effects.

 

Inflammatory signals promote inflammation by activating the microglia and astrocytes within the brain in ASD. SGLT2 inhibitors influence on the inflammation and neuroinflammation, SGLT2 inhibitors decrease the inflammatory factors levels, such as the M1 macrophages, STAT1 inflammatory transcription factor, cytokine interleukin-1β (IL-1β), tumor necrosis factor (TNF-α), and vascular cell adhesion protein (VCAM) in neurodevelopmental diseases

 

 

Distribution of the SGLT receptors in the CNS. 1. Brain cortex (pyramidal cells); 2. Purkinje neurons; 3. Hippocampus; 4. Hypothalamus; 5. Micro vessels; 6. Amygdala cells; 7. Periaqueductal gray; 8. Dorsomedial medulla.

 

Such a distribution of the SGLT2 receptors [114] could potentially be responsible for their intriguing neuroprotective qualities, which could be beneficial in several neurological disorders, including ASD [99]. The SGLT2 inhibitors’ proposed mechanisms are presented in Figure 3. The antioxidant effect of the SGLT2 inhibitors can be attributed to their stimulatory action on the nuclear factor erythroid 2 (Nrf2)- related factor 2 pathway [115]. This displays the antioxidant activity because of their genetic expression of the antioxidant proteins, including glutathione-s-transferase (GST), SOD, and NADPH quinone dehydrogenase-1 to protect against cellular apoptosis [116]. The anti-inflammatory characteristics of the SGLT2 inhibitors could be accredited to the downregulation of NF-KB, which decreases IL-1β and the TNF-α expression [117]. Empagliflozin has the highest selectivity for the SGLT2 receptors (2500-fold) when compared to dapagliflozin which has (1200-fold) selectivity, and canagliflozin (250-fold) [118,119]. Therefore, in the context of the neuroprotective effects associated with the SGLT1 and SGLT2 receptors’ inhibition, canagliflozin was hypothetically preferred over other SGLT2 inhibitors, due to its dual SGLT1/SGLT2 inhibition capability [120].

 

SGLT2 inhibitors have the potential to improve ASD patients’ behavioral and brain disruptions by increasing the cerebral brain derived neurotrophic factor and reducing the cerebral oxidative stress, including elevated the GSH and catalase activity, reduced MDA, amyloid β levels, plaque density, and acetylcholinesterase

 

ASD remains a global health dilemma, as it is a chronic condition, and is incurable, leading to a reduced quality of life. It is crucial to find the mutual molecular mechanisms of ASD and redefine the indications for the well-studied medication with numerous pleiotropic effects to find a solution. This review has disclosed the impact of the SGLT2 inhibitors in neurological diseases, which could relate to ASD as it shares multiple pathways and mutual biomarkers. SGLT2 inhibitors display several neuroprotective properties, highlighting their therapeutic potential for ASD patients, as these agents have the capability to inhibit the acetylcholinesterase enzyme, reduce the elevated levels of the oxidative stress in the brain, and restore the anabolism and catabolism balance. Moreover, clinical intervention studies are vital to determine whether the displayed methods are useful as the SGLT2 inhibitors have never been tested on ASD directly. Currently, our research team is conducting a preclinical experiment to assess the effects of canagliflozin on the VPA-induced ASD in Wistar rats.

  

Back to the NLRP3 Inflammasome

Ponstan (Mefenamic acid) is one of the few available drugs that is known to be a potent inhibitor of an inflammatory pathway called the NLRP3 inflammasome.  It is mainly present macrophages, a type of white blood cell in the immune system.  The role of macrophages includes gobbling up pathogens.  

In the brain the microglia are the resident macrophages.  The microglia have multiple functions in the brain and we know that in autism they can be stuck in an overactivated state and then do not fulfil their other functions.

In many diseases activation of the NLRP3 inflammasome in local macrophages occurs.  Inhibiting this process can disrupt the disease process.

My guess is that this is the mechanism by which Ponstan is improving cognition in some of the people with autism who are taking it.

In the paper below we see that people taking Ponstan to treat their prostate cancer (PCa) experience an improvement in their cognition.

 

Improve cognitive impairment using mefenamic acid non-steroidal anti-inflammatory therapy: additional beneficial effect found in a controlled clinical trial for prostate cancer therapy 

Inflammation is an essential component of prostate cancer (PCa), and mefenamic acid has been reported to decrease its biochemical progression. The current standard therapy for PCa is androgen deprivation therapy (ADT), which has side effects such as cognitive dysfunction, risk of Alzheimer’s disease, and dementia. Published results of in vitro tests and animal models studies have shown that mefenamic acid could be used as a neuroprotector. Objective: Examine the therapeutic potential of mefenamic acid in cognitive impairment used in a controlled clinical trial. Clinical trial phase II was conducted on patients undergoing ADT for PCa. Two groups of 14 patients were included. One was treated with a placebo, while the other received mefenamic acid 500 mg PO every 12hrs for six months. The outcome was evaluated through the Mini-Mental State Examination (MMSE) score at six months. At the beginning of the study, both groups had similar MMSE scores (mefenamic acid vs. placebo: 26.0±2.5 vs. 27.0±2.6, P=0.282). The mefenamic acid group improved its MMSE score after six months compared with the placebo group (27.7±1.8 vs. 25.5±4.2, P=0.037). Treatment with mefenamic acid significantly increases the probability of maintained or raised cognitive function compared to placebo (92% vs. 42.9%, RR=2.2, 95% CI: 1.16-4.03, NNT=2.0, 95% CI: 1.26-4.81, P=0.014). Furthermore, 42.9% of the placebo group patients had relevant cognitive decline (a 2-point decrease in the MMSE score), while in patients treated with mefenamic acid, cognitive impairment was not present. This study is the first conducted on humans that suggests that mefenamic acid protects against cognitive decline.

 

In the AEA mouse model of MS (multiple sclerosis) we see the role again of NLRP3 on cognition. 

Inhibition of the NLRP3-inflammasome prevents cognitive deficits in experimental autoimmune encephalomyelitis mice via the alteration of astrocyte phenotype 

Some studies have indicated that NLRP3 inflammasome activation is involved in mediating synaptic dysfunction, cognitive impairment, and microglial dysfunction in AD models, and that the inhibition of the NLRP3 inflammasome attenuates spatial memory impairment and enhances Aβ clearance in AD model.  However, there is no research on NLRP3 inflammasome in MS-related cognitive deficits. In our study, we found that microglia and NLRP3 inflammasome were activated in the hippocampus of EAE mice, while pretreatment with MCC950 inhibited the activation of microglia and NLRP3 inflammasome

 

Again, we see a benefit from inhibiting NLRP3 in Alzheimer’s. 

Novel Small-Molecule Inhibitor of NLRP3 Inflammasome Reverses Cognitive Impairment in an Alzheimer’s Disease Model

Aberrant activation of the Nod-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome plays an essential role in multiple diseases, including Alzheimer’s disease (AD) and psoriasis. We report a novel small-molecule inhibitor, NLRP3-inhibitory compound 7 (NIC7), and its derivative, which inhibit NLRP3-mediated activation of caspase 1 along with the secretion of interleukin (IL)-1β, IL-18, and lactate dehydrogenase. We examined the therapeutic potential of NIC7 in a disease model of AD by analyzing its effect on cognitive impairment as well as the expression of dopamine receptors and neuronal markers. NIC7 significantly reversed the associated disease symptoms in the mice model. On the other hand, NIC7 did not reverse the disease symptoms in the imiquimod (IMQ)-induced disease model of psoriasis. This indicates that IMQ-based psoriasis is independent of NLRP3. Overall, NIC7 and its derivative have therapeutic prospects to treat AD or NLRP3-mediated diseases.

 

What about sepsis (blood poisoning)? 

Mitochondrial protective effects caused by the administration of mefenamic acid in sepsis

The pathophysiology of sepsis may involve the activation of the NOD-type receptor containing the pyrin-3 domain (NLPR-3), mitochondrial and oxidative damages. One of the primary essential oxidation products is 8-oxoguanine (8-oxoG), and its accumulation in mitochondrial DNA (mtDNA) induces cell dysfunction and death, leading to the hypothesis that mtDNA integrity is crucial for maintaining neuronal function during sepsis. In sepsis, the modulation of NLRP-3 activation is critical, and mefenamic acid (MFA) is a potent drug that can reduce inflammasome activity, attenuating the acute cerebral inflammatory process. Thus, this study aimed to evaluate the administration of MFA and its implications for the reduction of inflammatory parameters and mitochondrial damage in animals submitted to polymicrobial sepsis. To test our hypothesis, adult male Wistar rats were submitted to the cecal ligation and perforation (CLP) model for sepsis induction and after receiving an injection of MFA (doses of 10, 30, and 50 mg/kg) or sterile saline (1 mL/kg). At 24 h after sepsis induction, the frontal cortex and hippocampus were dissected to analyze the levels of TNF-α, IL-1β, and IL-18; oxidative damage (thiobarbituric acid reactive substances (TBARS), carbonyl, and DCF-DA (oxidative parameters); protein expression (mitochondrial transcription factor A (TFAM), NLRP-3, 8-oxoG; Bax, Bcl-2 and (ionized calcium-binding adaptor molecule 1 (IBA-1)); and the activity of mitochondrial respiratory chain complexes. It was observed that the septic group in both structures studied showed an increase in proinflammatory cytokines mediated by increased activity in NLRP-3, with more significant oxidative damage and higher production of reactive oxygen species (ROS) by mitochondria. Damage to mtDNA it was also observed with an increase in 8-oxoG levels and lower levels of TFAM and NGF-1. In addition, this group had an increase in pro-apoptotic proteins and IBA-1 positive cells. However, MFA at doses of 30 and 50 mg/kg decreased inflammasome activity, reduced levels of cytokines and oxidative damage, increased bioenergetic efficacy and reduced production of ROS and 8-oxoG, and increased levels of TFAM, NGF-1, Bcl-2, reducing microglial activation. As a result, it is suggested that MFA oinduces protection in the central nervous system early after the onset of sepsis.

  

Conclusion

One reader of this blog attributes her son’s autism to his sepsis (blood poisoning) at birth. It is pretty clear from one of today’s papers that perhaps babies with sepsis should be treated with Ponstan (Mefenamic acid) to prevent damage to their brain.  I was recently contacted by another parent where sepsis occurred at birth. 

I think the researchers make a strong case that the pleiotropic effects of SGLT2 inhibitors that benefit Alzheimer’s, Parkinson’s and ALS very likely will also be beneficial in some autism.  They plan to test canagliflozin on rats with valproic acid-induced autism.

I have to say to Eszter that I actually think inhibiting the NLRP3 inflammasome might be the Neurologist’s best friend forever (BFF), perhaps even better than an SGLT2 inhibitor.

What is for sure is that both (SGLTi and NLRP3i) should be subject of clinical trials in autism. I suggest going straight humans rather than rats.

I have had positive feedback so far on my suggestion that low dose (250 mg) Ponstan/Mefenamic acid could be an effective long term autism therapy.  We do have to mention that Knut Wittkowski has patented its use in autism; he proposed it as a preventive measure in 2-3 year olds to redirect severe non-verbal autism towards Asperger’s. I selected it to treat extreme sound sensitivity, but later witnessed its pleiotropic effects.

If anyone has experience on the use of an SGLT2 inhibitor in autism, I would be very interested to read about it.

We should add Ponstan to the long list of drugs in this autism blog that may be beneficial in MS (Multiple sclerosis). (ALA, Clemastine, NAG, Ibudilast, DMF, Ponstan etc).

P.S.

A last word from Google

Having noted my recent googling activity, I was today sent the following news item by Google. 

Harnessing the Brain’s Immune Cells to Stave off Alzheimer’s and Other Neurodegenerative Diseases

Researchers have identified a protein that could be leveraged to help microglia in the brain stave off Alzheimer’s and other neurodegenerative diseases

But how does SYK protect the nervous system against damage and degeneration? We found that microglia use SYK to migrate toward debris in the brain. It also helps microglia remove and destroy this debris by stimulating other proteins involved in cleanup processes. These jobs support the idea that SYK helps microglia protect the brain by charging them to remove toxic materials.

 

High dose Betaine/TMG, Low Dose Ponstan, Galavit, Humira, HMB (β-hydroxy-β-methylbutyrate) and Cetirizine for Palilalia/Scripting

 

Our reader in Canada, AJ, did highlight a case series from Norway that showed that high dose Betaine/TMG was effective in improving functioning in people with autism due to creatine transporter deficiency.  The use of Betaine/TMG was really just stumbled upon and the authors considered what the beneficial possible mode of action could be. 

Betaine (TMG) and Gene Therapy as potential alternatives to Bumetanide Treatment in Autism? 

The effect was only present at high dose (7-10 g a day) not the much lower dose used by some DAN/MAPS doctors, who do prescribe TMG and the closely related DMG.

The paper suggested that one possible effect might have been lowering chloride levels within neurons.  This is also the effect of Bumetanide.

AJ suggested that Betaine/TMG might be an alternative to Bumetanide and one that does not need a prescription.

Our reader Nancy reported a benefit in her adult son.

The question is not whether or not high dose TMG is a useful therapy, we already know that it is, in some cases. The question is whether it is a bumetanide alternative.

My conclusion is that high dose TMG does not seem to be a bumetanide alternative.  If it was an effective alternative then I would be suggesting everyone using bumetanide should go and buy some.

I did try TMG for s couple of weeks and did not see any additional effect over the continued therapy of 2mg of bumetanide.  In our case there is a benefit from additional bumetanide/Azosemide. If TMG shared the same mode of action as Bumetanide then 7g TMG + 2mg Bumetanide should show some improvement over 2mg Bumetanide.  It did not.

There is a long list of other modes of action to explain why Nancy’s son and the two Norwegians improved.

 

Low dose Ponstan for sound sensitivity

Low dose Ponstan (Mefenamic Acid) was proposed as a treatment for sound sensitivity.  Within Europe it seems that Greece is the place to buy Ponstan; it is sold OTC and cheap.  One pack (15 x 500mg) costs less than 2 USD/EUR.

In some people the effect of 250mg lasts all day, while for others it lasts for a few hours.

Ponstan is also widely used as a syrup to reduce fever in young children (antipyretic).

In the US the common brand name is Ponstel, but the price is dramatically higher.

Galavit + Cromolyn Sodium

The combination of the common mast cell stabilizer Cromolyn Sodium, used by many readers, with a Russian drug called Galavit is used by at least two readers. Dragos recently told us that the combination has put an end to his adult son’s aggressive behaviors.

Galavit has multiple anti-inflammatory modes of action.  It is not a mast cell stabilizer like Cromolyn Sodium.

Galavit is not expensive, but may hard to get hold of.

It does look like there is an overlap between responders to Verapamil and responders to Galavit.  So, if you respond well to Verapamil but get one of the rare side effects, like Maja’s daughter, it might be worth investigating further. 

Humira 

Humira is a TNF alpha inhibitor normally used to treat auto-immune conditions like rheumatoid arthritis, Cohn's disease, ulcerative colitis, psoriasis and juvenile arthritis.

I was recently contacted by an Aspie lady with auto-immune conditions, who found Humira not only controlled those conditions but moderated her autism symptoms, notably sound sensitivity.  One injection produced a benefit that lasted 7 weeks.

Kanner’s subject #1 went on to develop juvenile arthritis and this made his autism much worse.  There was no Humira back in his day, but his arthritis did respond to treatment.

Apparently, many children with autism and GI problems are taking Humira. 

IVIG seems to be the “go-to” therapy for immunomodulation in autism.  It is now quite commonly used in the US, but much less so elsewhere due to the cost.

I wonder if Humira might be an alternative for some?

 

HMB (β-hydroxy-β-methylbutyrate)

Our reader Natasa did mention the sports supplement HMB to me.

It has many interesting modes of action and it is a precursor to the ketone BHB, which has been covered in great depth in this blog.

Ketone Therapy in Autism (Summary of Parts 1-6)

In Europe ketone supplements like BHB fell foul of the rules on supplements and have been banned. In the US they are widely sold.

If you want to try BHB, by cannot buy it in Europe, you might want to look into HMB (β-hydroxy-β-methylbutyrate).

 

Cetirizine for Palilalia/Scripting 

I am a big fan of the OTC antihistamine Cetirizine/Zyrtec and I was interested to read the recent comment below about its effect on one 12-year-old boy.

“I realize this is 5 years old, but as a result of this blog, I tested cetirizine on my 12 yo yesterday. He has a nonstop palilalia (obsessive speaking that is nonsense or only makes sense to him). It's his "chief feature" and inhibits social development. For 4 glorious hours, it went away. Today, I gave him 5 mg of Zyrtec again. Yet again, the palilalia went away, AND he had strong focus on school (he has serious attention issues).”

 

Many people’s autism gets worse when auto-immune conditions flare up.  In some cases, the auto-immune condition is very mild, but the consequences are not.  For one person the result is aggressive behavior, while in another it is talking nonsense.

Personalized/Precision Medicine for Sound Sensitivity in Autism, Bipolar and Schizophrenia?

 

Stop the Noise!

 

Conventional wisdom, even among enlightened neurologists like Manuel Casanova, is that you cannot medically treat the sensory issues that occur in neurological conditions like autism, bipolar and schizophrenia.

This blog is very much driven by the peer-reviewed literature, but very often seems to comes up with alternative interpretations to what the doctors will say.  Today is another of those days.

I do tell people that you can very easily get things 100% back to front when developing personalized/precision medicine.  The general idea was correct, but the effect was the exact opposite to what was hoped for.  This is not a failure; this is a learning experience.  Today we see that what works in schizophrenia is the exact opposite of what works in bipolar.  I do like to include schizophrenia and bipolar in my autism posts, because there is a big overlap between them and the broad umbrella of dysfunctions found in autism.

Sensory problems are very common in autism, bipolar and schizophrenia.

This post is mainly about issues with sound.  Vision is closely related. Smell, taste and texture may be less closely related. 

Sound/Hearing issues in autism 

Very often young children with autism do not respond to their name, or some other sounds; the natural first step is to check their hearing.  The majority of the time, their hearing turns out to be perfect.

As the child gets older and struggles with sounds like a baby crying, or a dog barking, parents may begin to feel their child’s hearing is too good!

 

The medical terms

 

Hyperacusis is a disorder in loudness perception and should mean you hear sounds too loudly.  The opposite term is hypoacusis and in the medical jargon it means you are going deaf, rather than having a volume perception problem

Tinnitus is hearing sounds that do not exist, but there are many possible causes.

Misophonia means hatred of sound, but those hated sounds are often very specific repeated human sounds like noisy eating, chewing, sniffing, coughing or machine-made sounds like a noisy clock ticking, or even a leaf blower.

There does appear to be a visual equivalent of sound Misophonia.

For some people, visual triggers can cause a similar reaction. This might happen if you see someone:

• wagging their legs or feet (foot flapping)
• rubbing their nose or picking at their finger nails
• twirling their hair or pen
•  chewing gum 

Some people suffer from a combination of sound disorders.  Many people with tinnitus also suffer from Misophonia. 

I think many people with autism are affected by a combination of Hyperacusis and Misophonia.

It seems that many people with Asperger’s suffer from hyperacusis, a substantial minority experience tinnitus. Almost all who suffer tinnitus also experience hyperacusis.

I think it might be hard to know if a person with severe autism and ID had tinnitus.

 

Tinnitus and hyperacusis in autism spectrum disorders with emphasis on high functioning individuals diagnosed with Asperger's Syndrome

Objectives: To evaluate the prevalence of tinnitus and hyperacusis in individuals with Asperger's Syndrome (AS).

Methods: A home-developed case-history survey and three item-weighted questionnaires: Tinnitus Reaction Questionnaire (TRQ), Tinnitus Handicap Inventory (THI), and the Hyperacusis Questionnaire (HQ) were employed. These tools categorize the subjective response to tinnitus and hyperacusis. The research tools were mailed to a mailing list of individuals with Asperger's Syndrome.

Results: A total of 55 subjects diagnosed with AS were included in the analysis (15.5% response rate). Sixty-nine percent of all respondents (38/55) reported hyperacusis with an average HQ score of 20.7. Furthermore, 35% (19/55) reported perceiving tinnitus with average scores of 27 for the TRQ and 23 for the THI. Thirty-one percent (17/55) reported both hyperacusis and tinnitus. The prevalence of hyperacusis in the AS respondents remained relatively constant across age groups.

Conclusions: Hyperacusis and tinnitus are more prevalent in the ASD population subgroup diagnosed with AS under DSM-IV criteria than in the general public. Hyperacusis also appears to be more prevalent in the AS population than in the ASD population at large. Future research is warranted to provide insight into the possible correlation between tinnitus and hyperacusis symptoms and the abnormal social interactions observed in this group.

  

All three terms are just observation diagnoses, they do not tell you what is the underlying biological cause.  In this blog we are interested in the underlying biology, because the goal is to find an effective treatment.

Hearing issues are common comorbities of well-known medical conditions; for example, people with type 1 diabetes may well suffer from tinnitus and hypoacusis.

 

 

Schematic block diagram of mechanisms that produce misophonia, hyperacusis, tinnitus, polycusis, and other false auditory percepts. Afferents from the cochlea, saccule, somesthetic pathways, and visceral sensory pathways contribute to processing in auditory lemniscal pathways. Modular thalamocortical processing is hypothesized to contribute (1) a common component to comorbid features of hyperacusis and tinnitus, (2) a component that produces unique features of tinnitus, and (3) component(s) for other false auditory perceptions. A parallel, interoceptive, and affective network produces the aversion, annoyance, fear, and pain-like features that may be associated with hyperacusis and misophonia

Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6453992/

  

 The research terms

The medical world is often rather short of enough descriptive words, just think about all those people with totally different biological conditions all being diagnosed with “autism”.

A really useful term you will find in the research is sensory gating.

 

Sensory gating is a process by which irrelevant stimuli are separated from meaningful ones.  Imagine the boy with Asperger’s sitting in a private room taking his important exams.  He is alone with the invigilator and maybe a clock on the wall.  The clock might be making a ticking sound or the invigilator might be chewing gum.  All this clever boy has to do is to concentrate on the exam and show how smart he is.  The noisy clock, or the chewing sound, should be irrelevant, but instead the boy cannot filter out these sounds and ignore them.

I had exactly this case put to me at an autism conference by a concerned Grandfather, whose clever grandson failed his important exams.

You can actually measure sensory gating using headphones to provide the annoying repetitive sound and an EEG to measure how the person’s brain responds.  The first sound should trigger the brain’s response, but when the sound keeps repeating the response should fade away.  The person has learned to filter out the annoying but irrelevant sound.

Imagine you are in a storm and the rain is beating down on a glass roof or windows.  The first sound alerts you to the storm.  Did you leave the upstairs window open? Perhaps you were drying something outside?  You might have to take some urgent action, so you want an alarm bell to go off in your head.  Panic over, you can then just ignore the sound of the rain and before you know it the storm is over.

There are different types of sensory gating, the most well studied is called P50.

People with schizophrenia often have deficits in gating the neuronal response of the P50 wave, which is why P50 is the most widespread method of diagnosis. The test is conducted through having the patients hear two uniform sounds with an interval of 500 milliseconds. While the patients are hearing the sound, an EEG cap is used to measure the brain activity in response to those sounds. A normal subject shows a decrease in brain activity while hearing a second sound, while a subject showing equal brain activity to the first sound has impaired sensory gating.

Impaired P50 sensory gating is very common in schizophrenia, also occurs in autism bipolar and even dementia.

There can also be Impaired gating of N100 and P200.  The actual definition of these terms gets complicated and you do not have to go into this level of detail unless you are really interested

 

What is N100 event-related potential? 

The N100 is a negative waveform that peaks at approximately 100 milliseconds after stimulus presentation. Its amplitude is measured using electroencephalography (EEG) and may be dysfunctional in people with schizophrenia who show an inability to “gate” or inhibit irrelevant sensory information, ultimately leading to conscious information overload. To test this, paired auditory clicks are presented, separated by a short interval, usually of 0.5 seconds. The first click initiates or conditions the inhibition, while the second (test) click indexes the strength of the inhibition. An absence of a reduced response to the second stimulus is interpreted as a failure of inhibitory mechanisms, postulated to represent a defect in sensory gating.

 

What is the evidence for N100 event-related potential? 

Moderate to high quality evidence finds a medium-sized reduction in N100 amplitude to the first stimulus, but not to the second stimulus. Review authors suggests this reflects a deficit in processing of auditory salience rather than in inhibition.

 

 

  

 

P50-N100-P200 sensory gating deficits in adolescents and young adults with autism spectrum disorders

 

Highlights 

·        In the paired-click paradigm, ASD individuals displayed a significant N100 gating deficit.

·        N100 gating deficit was associated with symptom severity of sensory sensitivity.

·        P50 and P200 in ASD did not deviate from the typically developing controls.

·        P50 and P200 were associated with social deficits and attention switching difficulty in ASD.

 We found that compared to TDC, ASD participants had significant N100 suppression deficits reflected by a larger N100 S2 amplitude, smaller N100 ratio of S2 over S1, and the difference between the two amplitudes. N100 S2 amplitude was significantly associated with sensory sensitivity independent of the diagnosis. Although there was no group difference in P50 suppression, S1 amplitude was negatively associated with social deficits in ASD. P200 gating parameters were correlated with attention switching difficulty. Our findings suggest N100 gating deficit in adolescents and young adults with ASD. The relationships between P50 S1 and social deficits and between N100 S2 and sensory sensitivity warrant further investigation.

  

Expanding our understanding of sensory gating in children with autism spectrum disorders

Highlights

 

·        Children with autism showed significantly reduced gating at P50, N1, and P2 event-related potential components.

·        Children with autism show reduced orientation to auditory stimuli compared to typically-developing children.

·        Time-frequency analysis show reduced neural synchronization of stimuli in children with autism.

Abstract

Objective

This study examined sensory gating in children with autism spectrum disorders (ASD). Gating is usually examined at the P50 component and rarely at mid- and late-latency components.

Methods

Electroencephalography data were recorded during a paired-click paradigm, from 18 children with ASD (5–12 years), and 18 typically-developing (TD) children. Gating was assessed at the P50, N1, P2, and N2 event-related potential components. Parents of all participants completed the Short Sensory Profile (SSP).

Results

TD children showed gating at all components while children with ASD showed gating only at P2 and N2. Compared to TD children, the ASD group showed significantly reduced gating at P50, N1, and P2. No group differences were found at N2, suggesting typical N2 gating in the ASD group. Time-frequency analyses showed reduced orientation and neural synchronization of auditory stimuli. P50 and N1 gating significantly correlated with the SSP.

Conclusion

Although children with ASD have impaired early orientation and filtering of auditory stimuli, they exhibited gating at P2 and N2 components suggesting use of different gating mechanisms compared to TD children. Sensory deficits in ASD may relate to gating.

Significance

The data provide novel evidence for impaired neural orientation, filtering, and synchronization in children with ASD.

 

Normal P50 Gating in Children with Autism, Yet Attenuated P50 Amplitude in the Asperger Subcategory 

Autism spectrum disorders (ASD) and schizophrenia are separate disorders, but there is evidence of conversion or comorbid overlap. The objective of this paper was to explore whether deficits in sensory gating, as seen in some schizophrenia patients, can also be found in a group of ASD children compared to neurotypically developed children. An additional aim was to investigate the possibility of subdividing our ASD sample based on these gating deficits. In a case–control design, we assessed gating of the P50 and N100 amplitude in 31 ASD children and 39 healthy matched controls (8–12 years) and screened for differences between groups and within the ASD group. We did not find disturbances in auditory P50 and N100 filtering in the group of ASD children as a whole, nor did we find abnormal P50 and N100 amplitudes. However, the P50 amplitude to the conditioning stimulus was significantly reduced in the Asperger subgroup compared to healthy controls. In contrast to what is usually reported for patients with schizophrenia, we found no evidence for sensory gating deficits in our group of ASD children taken as a whole. However, reduced P50 amplitude to conditioning stimuli was found in the Asperger group, which is similar to what has been described in some studies in schizophrenia patients. There was a positive correlation between the P50 amplitude of the conditioning stimuli and anxiety score in the pervasive developmental disorder not otherwise specified group, which indicates a relation between anxiety and sensory registration in this group

  

Treatments for sensory gating

We know that in schizophrenia impaired P50 gating is associated with alpha 7 nicotinic acetylcholine receptor (α7 nAChR) dysfunction and shown to be improved with nicotine and other α7 nAChR agonists.

Other α7 nAChR agonists include:-

·        Acetylcholine

·        Choline

·        Nicotine

·        Tropisetron

 

Galantamine is a positive allosteric modulator (PAM) of nAChRs

 

Why do people with schizophrenia love to smoke?

 

A truly remarkable observation is that smoking improves sensory gating in schizophrenia, but it has the opposite effect on people with bipolar.

 

Smoking as a Common Modulator of Sensory Gating and Reward Learning in Individuals with Psychotic Disorders

 

Motivational and perceptual disturbances co-occur in psychosis and have been linked to aberrations in reward learning and sensory gating, respectively. Although traditionally studied independently, when viewed through a predictive coding framework, these processes can both be linked to dysfunction in striatal dopaminergic prediction error signaling. This study examined whether reward learning and sensory gating are correlated in individuals with psychotic disorders, and whether nicotine—a psychostimulant that amplifies phasic striatal dopamine firing—is a common modulator of these two processes. We recruited 183 patients with psychotic disorders (79 schizophrenia, 104 psychotic bipolar disorder) and 129 controls and assessed reward learning (behavioral probabilistic reward task), sensory gating (P50 event-related potential), and smoking history. Reward learning and sensory gating were correlated across the sample. Smoking influenced reward learning and sensory gating in both patient groups; however, the effects were in opposite directions. Specifically, smoking was associated with improved performance in individuals with schizophrenia but impaired performance in individuals with psychotic bipolar disorder. These findings suggest that reward learning and sensory gating are linked and modulated by smoking. However, disorder-specific associations with smoking suggest that nicotine may expose pathophysiological differences in the architecture and function of prediction error circuitry in these overlapping yet distinct psychotic disorders.

  

When you look up P50 gating and also Misophonia in the clinical trials database, you get some Mickey Mouse behavioral treatments for misophonia.

For p50 gating you a decent list of drugs trialed in schizophrenia. 

 

 

 

My earlier posts on this subject:-

 

Sensory Gating in Autism, Particularly Asperger's

 

Cognitive Loss/Impaired Sensory Gating from HCN Channels - Recovered by PDE4 Inhibition or an α2A Receptor Agonist

 

 

"I did wonder how nicotine fits in, since in earlier post we saw that α7 nAChR agonists, like nicotine, improve sensory gating and indeed that people with schizophrenia tend to be smokers. It turns out that nicotine is also an HCN channel blocker. For a change, everything seems to fit nicely together. There are different ways to block HCN channels, some of which are indirect. One common ADHD drug, Guanfacine, keeps these channels closed, but in a surprising way."

 

Acute administration of Roflumilast enhances sensory gating in healthy young humans in a randomized trial. 

Abstract

 

INTRODUCTION:

Sensory gating is a process involved in early information processing which prevents overstimulation of higher cortical areas by filtering sensory information. Research has shown that the process of sensory gating is disrupted in patients suffering from clinical disorders including attention deficit hyper activity disorder, schizophrenia, and Alzheimer's disease. Phosphodiesterase (PDE) inhibitors have received an increased interest as a tool to improve cognitive performance in both animals and man, including sensory gating.

METHODS:

The current study investigated the effects of the PDE4 inhibitor Roflumilast in a sensory gating paradigm in 20 healthy young human volunteers (age range 18-30 years). We applied a placebo-controlled randomized cross-over design and tested three doses (100, 300, 1000 μg).

RESULTS:

Results show that Roflumilast improves sensory gating in healthy young human volunteers only at the 100-μg dose. The effective dose of 100 μg is five times lower than the clinically approved dose for the treatment of acute exacerbations in chronic obstructive pulmonary disease (COPD). No side-effects, such as nausea and emesis, were observed at this dose. This means Roflumilast shows a beneficial effect on gating at a dose that had no adverse effects reported following single-dose administration in the present study.

CONCLUSION:

The PDE4 inhibitor Roflumilast has a favourable side-effect profile at a cognitively effective dose and could be considered as a treatment in disorders affected by disrupted sensory gating.

  

Be wary of antipsychotics!!

 Now we see again that α2A Receptor agonists like guanfacine and clonidine will improve sensory gating. We should not be surprised that drugs with the opposite effect (antagonists) will make sensory gating worse.

 

α2A Receptor Antagonists

·         Idazoxan

·         1-PP (active metabolite of buspirone and gepirone, anti-anxiety drugs)

·         Asenapine

·         BRL-44408

·         Clozapine , an anti-psychotic drugs used in schizophrenia

·         Lurasidone an anti-psychotic drugs used in schizophrenia and in bipolar

·         Mianserin, an anti-depressant

·         Mirtazapine, an anti-depressant

·         Paliperidone an anti-psychotic drugs used in schizophrenia

·         Risperidone, an anti-psychotic drugs used in schizophrenia and autism

·         Yohimbine

   

Treatment for Hyperacusis

If you look up treatments and trials for hyperacusis (sound sensitivity) you see a list of cognitive behavioral therapies.

These are not nonsense. We used something similar to deal with Monty’s extreme aversion to crying babies when he was young.  Now when he hears a baby crying, he laughs.

But really, science has much more to offer than behavioral therapy.

I did write many years ago about hypokalemic sensory overload and its big brother hypokalemic periodic paralysis (HypoPP).  In both conditions it seems that low levels of potassium cause some pretty severe reactions.  Both conditions respond rapidly to an oral potassium supplement.

Though rare, we know that HypoPP is caused by a dysfunction in the ion channels Na_v1.4 and/or Ca_v1.1.

For decades one of the treatments for HypoPP has been a diuretic called Diamox/Acetazolamide.  Other treatments include raising potassium levels using supplements, or potassium sparing diuretics.

  

Way back in 2013, I defined a new term, in the post below:-

 Hypokalemic Autistic Sensory Overload

  

I showed an oral potassium supplement reduced sound sensitivity within 20 minutes, with a simple experiment anyone can do at home. 

Some people do find long term sensory relief just from the use of an oral potassium supplement once a day.  In my son’s case the affect does not last very long.

  

Therapies for hypokalemic sensory overload might be:-

 

·        A potassium supplement

·        A potassium sparing diuretic

·        Possibly Diamox/ Acetazolamide

·        Very likely, intra-nasal Desmopressin, this lower sodium levels and so will have the opposite impact on potassium levels

·        Ponstan, the NSAID that affects numerous potassium ion channels

 

In some people it appears that Humira, a long-acting TNF-alpha inhibitor, resolves visual and sound sensitivity.  I think this resolves a mixture of hyperacusis and Misophonia and the visual sensory equivalents.

 

 

Tinnitus

Tinnitus is an extremely common, but is generally regarded as something you just have to get used to; there are no approved drug therapies.

All kinds of things can lead to tinnitus. A head injury can lead to tinnitus, exposure to a loud sound is a common cause, but there is even drug-induced tinnitus. Tinnitus is a common comorbidity of diabetes.

There is gradual onset tinnitus and acute onset tinnitus.

Tinnitus is more likely to occur the older you get and often gets worse over time.

Clearly there are many sub-types of tinnitus and inevitably there will need to be multiple different therapies

 

 

Full graphic is available at fnins-13-00802-g004.jpg (4660×2924) (frontiersin.org)

 

The paper below is very comprehensive: 

Why Is There No Cure for Tinnitus? 

Tinnitus is unusual for such a common symptom in that there are few treatment options and those that are available are aimed at reducing the impact rather than specifically addressing the tinnitus percept. In particular, there is no drug recommended specifically for the management of tinnitus. Whilst some of the currently available interventions are effective at improving quality of life and reducing tinnitus-associated psychological distress, most show little if any effect on the primary symptom of subjective tinnitus loudness. Studies of the delivery of tinnitus services have demonstrated considerable end-user dissatisfaction and a marked disconnect between the aims of healthcare providers and those of tinnitus patients: patients want their tinnitus loudness reduced and would prefer a pharmacological solution over other modalities. Several studies have shown that tinnitus confers a significant financial burden on healthcare systems and an even greater economic impact on society as a whole. Market research has demonstrated a strong commercial opportunity for an effective pharmacological treatment for tinnitus, but the amount of tinnitus research and financial investment is small compared to other chronic health conditions. There is no single reason for this situation, but rather a series of impediments: tinnitus prevalence is unclear with published figures varying from 5.1 to 42.7%; there is a lack of a clear tinnitus definition and there are multiple subtypes of tinnitus, potentially requiring different treatments; there is a dearth of biomarkers and objective measures for tinnitus; treatment research is associated with a very large placebo effect; the pathophysiology of tinnitus is unclear; animal models are available but research in animals frequently fails to correlate with human studies; there is no clear definition of what constitutes meaningful change or “cure”; the pharmaceutical industry cannot see a clear pathway to distribute their products as many tinnitus clinicians are non-prescribing audiologists. To try and clarify this situation, highlight important areas for research and prevent wasteful duplication of effort, the British Tinnitus Association (BTA) has developed a Map of Tinnitus. This is a repository of evidence-based tinnitus knowledge, designed to be free to access, intuitive, easy to use, adaptable and expandable.

 

The next paper makes the key point that to treat tinnitus you need precision (personalized) medicine and apply the neuroscience.

 

Towards a Mechanistic-Driven Precision Medicine Approach for Tinnitus 

In this position review, we propose to establish a path for replacing the empirical classification of tinnitus with a taxonomy from precision medicine. The goal of a classification system is to understand the inherent heterogeneity of individuals experiencing and suffering from tinnitus and to identify what differentiates potential subgroups. Identification of different patient subgroups with distinct audiological, psychophysical, and neurophysiological characteristics will facilitate the management of patients with tinnitus as well as the design and execution of drug development and clinical trials, which, for the most part, have not yielded conclusive results. An alternative outcome of a precision medicine approach in tinnitus would be that additional mechanistic phenotyping might not lead to the identification of distinct drivers in each individual, but instead, it might reveal that each individual may display a quantitative blend of causal factors. Therefore, a precision medicine approach towards identifying these causal factors might not lead to subtyping these patients but may instead highlight causal pathways that can be manipulated for therapeutic gain. These two outcomes are not mutually exclusive, and no matter what the final outcome is, a mechanistic-driven precision medicine approach is a win-win approach for advancing tinnitus research and treatment. Although there are several controversies and inconsistencies in the tinnitus field, which will not be discussed here, we will give a few examples, as to how the field can move forward by exploring the major neurophysiological tinnitus models, mostly by taking advantage of the common features supported by all of the models. Our position stems from the central concept that, as a field, we can and must do more to bring studies of mechanisms into the realm of neuroscience.

  

I did have a quick look the clinical trials website to see if there have been any interesting trials that did show some benefit. 

I noted the following drugs: 

Lidocaine

Lidocaine, the anesthetic that targets sodium ion channels.  Careful titration allows for a high degree of selectivity in the blockage of sensory neurons.  This looks like a good idea. Originally, they played with intravenous delivery, but then moved no to transdermal.

 

Transdermal lidocaine as treatment for chronic subjective tinnitus: A Pilot Study

In this preliminary study, 5% transdermal lidocaine appears to be a potential treatment for chronic subjective tinnitus. The majority of subjects who completed 1 month of treatment had clinically significantly improved tinnitus. These findings are confounded however by the small sample size and significant drop out rate.

 

Clonazepam 

Clonazepam is a benzodiazepine drug that activates GABAa receptors.  The trials are a bit mixed and one showed it only worked when given together with Deanxit. Deanxit is a combination of Flupentixol, an antipsychotic, and melitracen an tricyclic antidepressant.

These look like bad options which will end up causing new problems over time. 

Clonazepam Quiets tinnitus: a randomised crossover study with Ginkgo Biloba

Conclusion Clonazepam is effective in treating tinnitus; G biloba is ineffective.

  

Administration of the combination clonazepam-Deanxit as treatment for tinnitus

Results: Significant tinnitus reduction was seen after intake of the combination clonazepam-Deanxit, whereas no differences in tinnitus could be demonstrated after the administration of clonazepam-placebo. This was true for all patients according to the following parameters: time patients are annoyed by the tinnitus (p = 0.026) and the visual analogue scale for tinnitus annoyance (p = 0.024).

 Conclusion: Although tinnitus reduction was recorded as modest, this article provides valuable data demonstrating a placebo-controlled tinnitus reduction after clonazepam and Deanxit intake.

 

Oxytocin

There already is a lot in the blog about oxytocin and I was surprised anyone had trialed it for tinnitus, but they did and it seems to provide a benefit.  As regular readers of this blog know, there looks to be a better way to deliver oxytocin to the brain than intra-nasal. We saw how a specific gut bacteria has the same effect (Biogaia Protectis). 

TinnitusTreatment with Oxytocin: A Pilot Study

Conclusion

These preliminary studies demonstrated that oxytocin may represent a helpful tool for treating tinnitus and further larger controlled studies are warranted.

 

Acamprosate

Acamprosate is used to treat alcoholics.

 “An inhibition of the GABA-B system is believed to cause indirect enhancement of GABA_A receptors.^[17] The effects on the NMDA complex are dose-dependent; the product appears to enhance receptor activation at low concentrations, while inhibiting it when consumed in higher amounts, which counters the excessive activation of NMDA receptors in the context of alcohol withdrawal”  

Impact of Acamprosate on Chronic Tinnitus: A Randomized-Controlled Trial 

Objectives: Tinnitus is a common and distressing otologic symptom, with various probable pathophysiologic mechanisms, such as an imbalance between excitatory and inhibitory mechanisms. Acamprosate, generally used to treat alcoholism, is a glutaminergic antagonist and GABA agonist suggested for treating tinnitus. Thus, we aimed to evaluate the efficacy and safety of acamprosate in the treatment of tinnitus.

Conclusions: The study results indicated a subjective relief of tinnitus as well as some degree of the electrophysiological improvement at the level of the cochlear and the distal portion of the auditory nerve among the subjects who received the acamprosate.

 

Magnesium

Magnesium supplementation, being cheap and OTC, is a common therapy for tinnitus.  It does seem to provide a benefit for some. 

Phase 2 study examining magnesium-dependent tinnitus

Conclusion: The results suggest that magnesium may have a beneficial effect on perception of tinnitus-related handicap when scored with the THI.

 

Neramexane

Neramexane is interesting because it is closely related to Memantine/Namenda, which was widely used in autism, but failed in its large clinical trial.  Memantine is seen as an NMDA receptor antagonist/blocker, but it also blocks  nicotinic acetylcholine receptors (nAChRs) which play a role in Alzheimer’s and sensory gating (Misophonia). Memantine also affects serotonin and dopamine receptors.

 Neramexane is a new drug being developed for Alzheimer’s and as a pain killer. 

A randomized, double-blind, placebo-controlled clinical trial to evaluate the efficacy and safety of neramexane in patients with moderate to severe subjective tinnitus

Neramexane is a new substance that exhibits antagonistic properties at α₉α₁₀ cholinergic nicotinic receptors and N-methyl-D-aspartate receptors, suggesting potential efficacy in the treatment of tinnitus.

 

Conclusions

This study demonstrated the safety and tolerability of neramexane treatment in patients with moderate to severe tinnitus. The primary efficacy variable showed a trend towards improvement of tinnitus suffering in the medium- and high-dose neramexane groups. This finding is in line with consistent beneficial effects observed in secondary assessment variables. These results allow appropriate dose selection for further studies.

 

Mirtazapine 

Mirtazapine is yet another drug that has been covered in this blog.  It is a very cheap anti-histamine / anti-depressant.

We saw in this blog that the effect is highly dose dependent.  It affects very many receptors and the overall effect depends on dosage. The antidepressant effect is at the dose of 15+mg.  In this person with tinnitus, they used 7.5mg. For some conditions the dose goes up to 60mg a day.

At very low dosages mirtazapine is a potent H1 anti-histamine and makes you very drowsy

One parent noted that low dose Mirtazapine had a highly beneficial effect in their child with autism.

 

Tinnitus Treatment With Mirtazapine

Auditory pathways are modulated by various neurotransmitters such as serotonin responsible for sound detection, location, and interpretation. The neurotransmitter gamma amino butyric acid (GABA) is inhibitory in the auditory system. Given that there is preferential innervation of the GABAergic neurons in the inferior colliculus by serotonergic neurons, it may be plausible then that antidepressant drugs, by increasing the availability of serotonin and thereby increasing GABAergic activity, provide relief from the symptoms of tinnitus.⁵ This report shows that mirtazapine may have a beneficial effect in the subgroup of patients suffering from tinnitus but exact mechanism is difficult to put forward.

 

Conclusion 

I think we are absolutely spoilt for choice.

So many possible therapies, each one effective in some cases.

The key is precision medicine, personalized to the individual case in question.  This approach was also proposed in the recent paper on Tinnitus, only without telling us what to actually do!

In my son, now 18 with what we can call treated severe autism, the clear winner so far is Ponstan (Mefenamic Acid).  Diclofen, a very common Fenamate class drug, does share the same effect, but to a lesser extent. 

Fenamates (Diclofenac, Ponstan etc): certainly for Alzheimer’s, maybe some Epilepsy, but Autism? I’m Impressed!

Low dose Roflumilast, the P50 sensory gating therapy (that is more for Aspies) has no sensory effect at all. It is the same dose as that proposed in the research to raise IQ.

The intranasal Desmopressin mentioned by one reader is another good choice to consider, but you may need to supplement sodium.  I think if you get a short term benefit from a 500mg potassium supplement, this is worth a try.

For Aspies low dose Roflumilast everyday looks worth a try, while Humira every 2 months look interesting, but it will be hard to get and is pricey.

For people with Schizophrenia, they could look at tobacco alternatives, which would include low-dose Roflumilast.

People with Bipolar might want to look at Mirtazapine – the opposite of nicotine and which also helps some cases of tinnitus.

For tinnitus I thought oxytocin looked a very safe option.  You have intranasal, or my preference the gut bacteria probiotic that stimulates oxytocin release in the brain.

Magnesium is a safe bet for tinnitus.  Transdermal lidocaine makes sense, but is a bit more daring.  Memantine might be worth a shot, if nothing else helps.

You can also increase sound and visual sensitivity. Low dose DMF (dimethyl fumarate) increases sound sensitivity and the TRH super-agonist Ceredist increases visual sensitivity.  For most people with autism, you likely do not need either effect.