Psilocybin, autism and depression: the psychedelic experience is apparently not needed

 

I like today’s post because it draws together some reader experience, autism research from the 1960s, with modern day lab research and human trials.

A distinct subgroup of our readers fall into what is today level 1 autism, which many think was better described as Asperger’s. Even though cognition and language are not impaired, some can have severe struggles, including anxiety, depression and feeling they do not quite fit in. Remarkably, in some cases just getting an official diagnosis provides a boost, “it's not me, it's my autism”. If that is sufficient therapy, then great.

For the Aspies seeking a better life, some end up looking at their serotonin receptors.

I recently wrote a review of all of them, but the Aspie focus tends to be 5-HT2A.

Rethinking the role of serotonin receptor signaling in improving autism symptoms: Prucalopride for a sub-group?

Incidentally, the mother who prompted that post tells me that her adult son continues to show the behavioral benefit from prucalopride one month later.

5-HT2A was the target of Ivar Lovaas back in 1966 at UCLA in Los Angeles. Lovaas is best known today for his work in Applied Behavioral Analysis (ABA).

Back in 1966 he published this paper:

Modificationof autistic behavior with LSD-25

The study involved a pair of identical autistic twin boys, then around five years old.

The researchers were interested in whether LSD could modify behaviours that were particularly difficult to change in severely affected children.

 

Our reader comments

One of the most notable comments in this blog was written by an Aspie who found a single experience with stimulating 5-HT2A provided a lasting beneficial shift in his mood.

You might wonder how such an effect could occur, like flipping a switch.

The recent research now explains why this likley happened.

 

The 1966 LSD study was tiny and exploratory by modern standards. It cannot establish that LSD was an effective treatment for autism, and the behavioural changes reported were principally observed during the drug sessions. It is therefore important not to read modern ideas about long-lasting psychedelic effects back into the 1966 experiment.

Nevertheless, the study is historically remarkable.

Lovaas was involved in research asking whether altering brain function could alter autistic behaviour.

Then the science took a different path.

 

60 years later we are back to psilocybin – depression in humans, autism in mice

A new study has taken the question into a modern genetic model of autism.

The researchers used mice lacking Cntnap2, a gene associated with neurodevelopmental disorders in humans. These mice show reduced sociability together with hyperactivity and repetitive behaviour.

A single dose of psilocybin produced a persistent increase in social behaviour.

The effect was detectable one day later and remained for at least two weeks. Importantly, the mice did not simply become more active: their overall exploration and locomotion did not show the same change.

And psilocybin did not correct everything.

The hyperactivity and repetitive grooming remained elevated.

This is therefore not evidence that psilocybin "reverses autism."

It is evidence that a brief pharmacological intervention can produce a persistent change in one particular behavioural phenotype in a particular genetic mouse model.

There was another important finding.

The same treatment did not increase sociability in genetically normal control mice.

That suggests something much more interesting than a simple "socialising" effect.

Perhaps the drug is interacting with an abnormal neural state.

 

The 5-HT2A receptor

Psilocybin's psychedelic effects are primarily mediated through the serotonin 5-HT2A receptor.

The researchers blocked this receptor before administering psilocybin.

The persistent improvement in sociability disappeared.

This gives us an important mechanistic sequence:

 

Psilocybin

↓

5-HT2A activation

↓

persistent biological change

↓

altered social behaviour

 

But then came the most surprising experiment.

The mice did not have to experience the psychedelic state

The researchers administered psilocybin while the mice were under light anaesthesia.

The animals therefore experienced the acute pharmacological action of psilocybin while unconscious.

When tested later while awake, they showed the same persistent increase in sociability.

In other words, an awake psychedelic experience was not required for the lasting behavioural effect in these mice.

The psychedelic experience is not itself the fundamental therapeutic mechanism.

It is one consequence of activating 5-HT2A receptors, while another consequence is a longer-lasting biological change in the brain.

 

What could produce a lasting effect?

One possibility is that the brief receptor signal initiates a cascade of molecular and cellular changes.

There is increasing evidence from psychedelic research that psilocybin can influence gene expression, neuronal structure, synaptic organisation and brain network function.

Epigenetic mechanisms may also be involved.

In the Cntnap2 work, the researchers found evidence that DNA-methylation machinery is required for the persistent behavioural effect. 

Researchers found that blocking DNMT1, a key DNA-methylation enzyme, prevented this persistent effect.

Importantly, DNMT1 inhibition did not prevent the acute 5-HT2A-related response.

This suggests DNA-methylation machinery acts downstream of 5-HT2A activation to maintain the longer-term change.

The finding points to a molecular mechanism whereby a brief drug exposure can produce behavioural effects long after the psychedelic experience has ended.

This suggests that a short-lived pharmacological signal may be converted into a longer-lasting change in gene regulation.

We do not yet know that psilocybin permanently rewrites the epigenome in these mice.

Nor do we know that the behavioural change is caused by a permanent epigenetic modification.

A more cautious model would be:

 

brief 5-HT2A stimulation

↓

intracellular signalling

↓

changes in gene regulation and possibly epigenetic state

↓

altered capacity for neural plasticity

↓

changes in neural circuits

↓

persistent change in behaviour

 

The important word is persistent, not permanent.

 

Could this matter for depression in autistic people?

This brings us back to humans.

Depression and persistent low mood occur in some autistic people, and this may be a particularly interesting population for psychedelic research.

Psilocybin has already produced persistent antidepressant effects in studies of people with major depressive disorder.

But there is an important unanswered question:

 

Would an autistic person with depression respond in the same way?

We do not yet know.

Autism is heterogeneous, and depression in an autistic person need not have exactly the same biological basis as depression in a non-autistic person.

Nevertheless, the new mouse findings make the question more interesting.

The drug did not simply increase sociability in every animal.

And now the experiment has returned to humans

The circle is becoming particularly interesting because researchers are now asking the same mechanistic question in humans.

A Stanford Phase 2 study, SPACE, is investigating psilocybin administered under general anaesthesia in people with major depressive disorder. The rationale is to suppress the noticeable psychological effects of psilocybin, making it possible to investigate whether effects can occur without the conscious psychedelic experience.

This is not an autism study, and it is small and experimental.

But scientifically it is fascinating.

Can separate the pharmacological action of psilocybin from the subjective psychedelic experience?

If lasting antidepressant effects were observed despite anaesthesia, that would provide important evidence that the biological action of 5-HT2A stimulation can produce therapeutic effects independently of the psychedelic experience.

 

From LSD in autistic humans to psilocybin in autistic mice and depressed humans

This brings us back to the historical arc.

1966 — UCLA

Lovaas and colleagues studied LSD in autistic children.

The question was whether changing brain function could modify autistic behaviour.

The following decades

Lovaas's research increasingly concentrated on behavioural intervention.

The question became whether changing the environment and learning experience could change behaviour and development.

2026 — autism mouse model

Researchers can now manipulate the biology much more precisely.

They can alter a specific autism-associated gene, activate 5-HT2A receptors, block the receptor, examine molecular pathways and administer the drug while the animal is unconscious.

And they find that a brief exposure to psilocybin can produce a behavioural effect that persists after the drug and the psychedelic state have disappeared.

2026 — depressed humans

Researchers are now taking the question back into humans.

Can psilocybin produce a lasting antidepressant effect without the person experiencing the psychedelic state?

The historical arc is therefore almost a circle.

 

Why did they choose the CNTNAP2 model and how this relates to Pitt Hopkins

The researchers did not choose the Cntnap2 mouse because it represents autism as a whole. They chose it because it is an established genetic model with a measurable reduction in sociability. Cntnap2-knockout mice show reduced social interaction, together with hyperactivity and repetitive behaviour. This gave the researchers a way to ask a very specific question: can psilocybin change an abnormal social phenotype?

The result was quite specific. Psilocybin increased the mice's preference for the social stimulus without significantly increasing their general exploration or movement. It also did not correct the hyperactivity or repetitive grooming.

The researchers also tested genetically normal mice. They did not show the same beneficial increase in sociability. This is important because it suggests that psilocybin may interact differently with a brain that already has an altered neurodevelopmental state, rather than simply acting as a general social enhancer.

 

Why is this relevant to Pitt Hopkins?

CNTNAP2 is particularly interesting in relation to Pitt Hopkins because biallelic CNTNAP2 mutations cause a Pitt-Hopkins-like neurodevelopmental disorder. Classical Pitt-Hopkins syndrome, however, is caused by alterations in TCF4.

There is also a biological relationship between the two genes. TCF4 is a transcription factor that can regulate CNTNAP2 expression. Thus, CNTNAP2 sits within a neuronal gene-regulatory network that is relevant to Pitt-Hopkins biology.

This does not mean that a Cntnap2-knockout mouse is a model of classical Pitt-Hopkins syndrome. The primary genetic abnormalities are different, and the findings cannot be directly extrapolated from Cntnap2 mice to people with Pitt Hopkins.

There is another important difference. Reduced social motivation is a clear phenotype of the Cntnap2 mouse, but it should not automatically be assumed to be the principal social problem in Pitt Hopkins syndrome.

People with Pitt Hopkins can have profound communication and social-communication difficulties, but many also actively seek attention, enjoy being with other people and show considerable social interest. In other words, the ability to communicate socially and the motivation to engage socially are not necessarily the same thing.

This means that if psilocybin were investigated in Pitt Hopkins, increasing social motivation would not necessarily be the most appropriate primary outcome.

Instead, researchers could ask whether it changes social communication, spontaneous communication, mood/affect, anxiety, repetitive behaviours, adaptive functioning or other measurable Pitt Hopkins phenotypes.

 

The research question

The Cntnap2 finding nevertheless raises an intriguing question for Pitt Hopkins:

If 5-HT2A activation can produce a persistent improvement in a behavioural phenotype caused by disruption of CNTNAP2, could it also modify some downstream consequences of TCF4 dysfunction?

The next logical experiment would therefore be to test psilocybin in a Tcf4 haploinsufficient Pitt Hopkins mouse model.

Researchers could examine not only behaviour but also the underlying biology:

• Does 5-HT2A activation alter the synaptic abnormalities associated with TCF4 deficiency?
• Does it affect gene expression or epigenetic regulation?
• Does it alter neuronal plasticity?
• Are any behavioural effects persistent after the drug has disappeared?
• Does the effect require the conscious psychedelic state, or could it occur under anaesthesia as in the Cntnap2 experiment?

The most interesting possibility would be a downstream compensation: the TCF4 mutation would remain, but a transient pharmacological intervention might alter some of the neuronal consequences of that mutation and allow the system to function differently.

 

Pitt-Hopkins is already being approached through epigenetics

There is an especially interesting parallel here because Pitt-Hopkins researchers are already testing an epigenetic strategy in humans. The RVL-001 trial, being conducted by Unravel Biosciences with the Pitt Hopkins Research Foundation in Colombia, is testing Vorinostat, a histone deacetylase (HDAC) inhibitor, in people with genetically confirmed Pitt Hopkins syndrome. The current exploratory study is small and is designed to examine safety and efficacy, as well as changes in the transcriptomic profile.

Vorinostat is approaching the problem from a very different direction than psilocybin. Rather than activating 5-HT2A receptors and potentially initiating downstream changes in neuronal signalling and plasticity, vorinostat directly alters epigenetic regulation by inhibiting HDAC enzymes, thereby changing how tightly DNA is packaged around histones and influencing gene expression.

There is a particularly strong rationale for this in Pitt Hopkins. In Tcf4-haploinsufficient mice, HDAC inhibition with vorinostat normalized abnormalities in hippocampal long-term potentiation and memory recall. Molecular studies also found changes in gene expression and DNA methylation associated with the treatment.

This creates an intriguing contrast:

Pitt-Hopkins genetic defect → TCF4 haploinsufficiency → abnormal gene regulation

Vorinostat: attacks the problem directly at the epigenetic/transcriptional level

versus

Psilocybin: 5-HT2A activation → intracellular signalling → potentially altered gene regulation/plasticity → possible downstream compensation.

 

In other words, these are two very different ways of trying to change the functional consequences of the same developmental genetic disorder.

The important point is that neither approach corrects the underlying TCF4 mutation. Both are attempting to modify downstream consequences of TCF4 deficiency.

 

Gene therapy

As was discussed in the recent post on gene therapy, there is now a fundamentally different approach being investigated in Pitt Hopkins: gene therapy.

Pitt Hopkins is caused by loss of function of one copy of TCF4, so gene therapy attempts to address the problem at its source. The investigational therapy MZ-1866 uses an AAV9 vector to deliver a functional copy of TCF4 to the brain.
It is being tested in a Phase 1/2 first-in-human clinical trial. The first participant was dosed in February 2026.
The current study is investigating safety and tolerability as well as potential clinical effects.
Unlike vorinostat or psilocybin, this approach is attempting to restore the missing genetic function itself.

Conclusion

Some Aspie readers of this blog have already established that a single dose of Psilocybin can produce long lasting improvements in social behavior. They skipped the mouse models and adopted the Nike approach.

The LSD trials in children in the 1960s assumed that the psychedelic experience was the therapy, now we see that this is not the case. You can sleep through it and still get the long lasting effect.

The beneficial effect in CNTNAP2 mice does indicate that the experiment should be repeated in the closely related Pitt Hopkins model. Of course, it should also be checked in idiopathic autism models like the BTBR and the maternal immune activation (MIA) model

In the prenatal valproate (VPA) model, psilocybin was previously tested and it did rescue the social-behavioural abnormalities. 

Note

Psilocybin is the main psychoactive compound found in “magic mushrooms.” It is converted in the body into psilocin, which produces the psychedelic effects. Research using purified psilocybin therefore studies the key active psychedelic component rather than the whole mushroom.

Cannabis Use and Potential Epigenetic Damage to Autism Genes

Today we consider another risk factor that may be contributing to the increase in prevalence of autism and it is about the father, for a change.  In the public's perception cannabis is a safe alternative way to treat all kinds of medical problems, many experts do not agree.

Cannabis may Epigenetically Mark Men’s Sperm for Autism

Fathers who use marijuana may be using it for two, suggests a study from Duke Medical Center. Although the study is small, encompassing just 24 men and 15 rats, it highlights a potential transgenerational effect of marijuana exposure—the passing on of sperm in which an autism-associated gene, DLGAP2, has accumulated extra epigenetic marks.

The Duke scientists, led by Susan Murphy, PhD, associate professor of obstetrics and gynecology, identified significant hypomethylation at DLGAP2 in the sperm of men who used marijuana compared to controls. A similar observation was made in the sperm of rats exposed to tetrahydrocannabinol (THC) compared to controls. This hypomethylated state was also detected in the forebrain region of rats born to fathers exposed to THC.

Murphy and colleagues said their findings do not establish a definitive link between cannabis use and autism, but the possible connection warrants further, urgent study, given efforts throughout the country to legalize marijuana for recreational and/or medicinal uses.

“This study is the first to demonstrate an association between a man’s cannabis use and changes of a gene in sperm that has been implicated in autism,” she emphasized. “Given marijuana’s increasing prevalence of use in the United States and the increasing numbers of states that have legalized its use, we need more studies to understand how this drug is affecting not only those who smoke it, but their unborn children.

“There’s a perception that marijuana is benign. More studies are needed to determine whether that is true.”

The original paper:-

Cannabis use is associated with potentially heritable widespread changes in autism candidate gene DLGAP2 DNA methylation in sperm

Parental cannabis use has been associated with adverse neurodevelopmental outcomes in offspring, but how such phenotypes are transmitted is largely unknown. Using reduced representation bisulphite sequencing (RRBS), we recently demonstrated that cannabis use is associated with widespread DNA methylation changes in human and rat sperm. Discs-Large Associated Protein 2 (DLGAP2), involved in synapse organization, neuronal signaling, and strongly implicated in autism, exhibited significant hypomethylation (p < 0.05) at 17 CpG sites in human sperm. We successfully validated the differential methylation present in DLGAP2 for nine CpG sites located in intron seven (p < 0.05) using quantitative bisulphite pyrosequencing. Intron 7 DNA methylation and DLGAP2 expression in human conceptal brain tissue were inversely correlated (p < 0.01). Adult male rats exposed to delta-9-tetrahydrocannabinol (THC) showed differential DNA methylation at Dlgap2 in sperm (p < 0.03), as did the nucleus accumbens of rats whose fathers were exposed to THC prior to conception (p < 0.05). Altogether, these results warrant further investigation into the effects of preconception cannabis use in males and the potential effects on subsequent generations.

Conclusion

I do not think anyone should be surprised that the THC in cannabis may leave an epigenetic tag on the DNA of the user and that it is passed down to following generations. We saw a long time ago that the same applies to people who smoke. It is just a question of which genes are most affected.  In the case of smoking it affected how your body deals with oxidative stress and this blocked how drugs for severe asthma (COPD) should work, so making COPD a very big problem for ex-smokers. Stopping smoking does not make the problem go away.

Any kind of prolonged chemical exposure may be a problem, the lead that was used in gasoline/petrol, current use of potent pesticides etc.  The same applies to electrical/magnetic exposure. Best not to live very close to high voltage power lines, or have a mobile phone mast on top of your building.

The concern is that these epigenetic markers are heritable and so accumulate over the generations, a kind of epigenetic pollution.

If great great grandpa worked down a coal mine or in a chemical factory, it may be recorded in your DNA.

HDAC Inhibitors for which Cancer/Autism?

Most types of autism can be viewed as the miss-expression of a few hundred genes, in some cases this has been caused by an initial defect in just one gene.  These single gene autisms are the ones that are usually studied.

Epigenetics has been covered previously in this blog and can either be made to look ultra-complex, which is the reality, or quite simple. The simple view is that in some people genes are miss-expressed because they have been tagged with heritable and removable markers; these can be wiped away. One type of epigenetic marker can be modified by an HDAC inhibitor or HDI.  

Some medical conditions featured genes turned off when they should be on. For example tumor suppressor gene (and autism gene) PTEN is turned off in the prostate of many males with prostate cancer; a neat therapy would be to switch it back on.  Deacetylation of PTEN by SIRT1 deacetylase and, by HDAC1, can stimulate its activity, so probably a good thing for people with this kind of common cancer.

In some types of autism there is a deficiency of a single protein because one of the two copies of the gene that encodes it does not work (Haploinsufficiency) and a neat therapy would be to make the remaining copy of that gene work harder. When I originally looked at epigenetics I thought it would not be possible to epigenetically tag the good copy of the specific gene, to switch it on. However it seems that we do not need to tag a specific gene, just provide the “post-it” notes and let the body do the tagging.

All this leads to the use of HDIs to treat cancer, leaving the body to figure out the hard part of which genes.  In reality an HDI will change the expression of numerous genes, not just the one(s) you wanted.

Different Colours of Tags

Just as those useful Post-It notes come in multiple colours, epigenetic markers come in different varieties.  This has been well studied in the cancer research.

HDAC1 inhibitors only affect part of the epigenome; there are other modifiers that are required to affect other genes.

In autism, as in cancer, you need to know which genes are miss-expressed and then you can see if an epigenetic therapy exists that covers them.  Put more simply if HDAC1 inhibitors affect only yellow post-its, which cancers/autisms would become treatable?

The more complex explanation regarding different colours of post-its:

“Important epigenetic modifications known to regulate gene expression. a DNA methylation of CpG islands in promoter regions by DNA methyltransferases (DNMT) represses gene activity. Posttranslational covalent histone modifications of lysine (K), arginine (R) or serine (S) residues in the “histone tail” also influence gene expression in different ways. b Histone acetylation (Ac) catalysed by histone acetyltransferases (HAT) is usually correlated to increased gene activity, whereas histone deacetylation caused by histone deacetylases (HDAC) is considered to decrease gene expression, even though histone hyperacetylation not always matches regions of increased gene activity. c Histone methylation (Me) and demethylation by histone methyltransferases (HMT) and histone demethylases (HDM) at lysine or arginine residues show different effects on gene activity depending on number and position of methyl groups. d Histone ubiquitinylation (Ub) at lysine residues alters histone structure and allows access of enzymes involved in transcription. e Histone phosphorylation (P) at distinct serine residues is known to be associated with increased gene expression, and it is also involved in DNA damage response and chromatin remodelling. Phosphorylation at linker histone (LH) H1 is considered to be a signal for the release of histone H1 from chromatin. In general, epigenetic regulation depends on the addition of epigenetic marks by writer enzymes (e.g. DNMT, HMT, HAT) and the removal of these marks by epigenetic eraser enzymes (e.g. HDAC and HDM) as well as epigenetic reader enzymes (not shown in this figure)”

https://clinicalepigeneticsjournal.biomedcentral.com/articles/10.1186/s13148-015-0095-z

Treating cancer is always going to be more difficult than treating autism because by the time it has been identified a whole cascade of changes is already underway and whereas autism is not degenerative, cancer by definition is. So even a very partially effective cancer drug might be potent enough for autism, or just a tiny dose of an effective cancer drug.

Source: https://www.sciencedirect.com/science/article/pii/S1044579X17300536

This post is about HDAC1&2 / yellow Post-its 

1.  The Grant Application 

Discovery of Novel Drugs for Autism

The goal of this study is to discover novel, mechanism-based pharmacological intervention for autism, a devastating neurodevelopmental disorder with no treatment currently. Genetic sequencing has revealed extensive overlap in risk genes for autism and for cancer, many of which are chromatin remodeling factors important for transcriptional regulation, suggesting the possibility of repurposing the anti-cancer drugs targeting epigenetic enzymes for autism treatment. ASDDR LLC and Yan Lab at SUNY-Buffalo propose to jointly investigate the hypothesis that histone deacetylase (HDAC) inhibitors are able to restore the expression of key autism risk factors and induce long-lasting rescue of autism-like behavioral and synaptic deficits. Combined behavioral, biochemical and electrophysiological approaches will be used to address two specific aims. 

Aim 1. To discover HDAC inhibitors that can alleviate autism-like behavioral deficits in autism mouse models. Yan lab screened a number of drugs and found that a brief treatment with the highly potent and class I-specific HDAC inhibitor, romidepsin (Istodax, an FDA-approved anti-cancer agent) at the very low dose, led to dramatic and prolonged rescue of the social deficits in the Shank3-deficient mouse model of autism. To determine whether this pharmacological agent can serve as a tool compound for autism drug development, its therapeutic efficacy and safety will be examined in two different models of autism, Shank3-deficient mice and BTBR mice.

Aim 2. To identify the molecular targets of HDAC inhibitors as benchmarks for the treatment of autism. For the discovery of effective drugs to treat autism, the molecular pathways on which HDAC inhibitors act to alleviate the autism-like behavioral deficits in Shank3-deficient mice need to be understood. We will reveal the potential benchmark, such as actin regulators and NMDARs, as molecular targets of romidepsin. This phase I preclinical study will provide great promise for the discovery of new and effective pharmacological agents to treat the social interaction deficits, a core symptom of autism.

Public Health Relevance

This project is to discover novel, mechanism-based therapeutic strategies for autism. The corporate and academic partners propose to jointly investigate the hypothesis that histone deacetylase (HDAC) inhibitors are able to restore the expression of key autism risk factors and induce long-lasting rescue of autism-like behavioral and synaptic deficits.

2. Study Press Release 

Autism’s social deficits are reversed by an anti-cancer drug

Using an epigenetic mechanism, romidepsin restored gene expression and alleviated social deficits in animal model of autism 

 “The advantage of being able to adjust a set of genes identified as key autism risk factors may explain the strong and long-lasting efficacy of this therapeutic agent for autism.”

BUFFALO, N.Y. — Of all the challenges that come with a diagnosis of autism spectrum disorder (ASD), the social difficulties are among the most devastating. Currently, there is no treatment for this primary symptom of ASD. New research at the University at Buffalo reveals the first evidence that it may be possible to use a single compound to alleviate the behavioral symptoms by targeting sets of genes involved in the disease.

The research, published today in Nature Neuroscience, demonstrated that brief treatment with a very low dose of romidepsin, a Food and Drug Administration-approved anti-cancer drug, restored social deficits in animal models of autism in a sustained fashion.

The three-day treatment reversed social deficits in mice deficient in a gene called Shank 3, an important risk factor for ASD. This effect lasted for three weeks, spanning the juvenile to late adolescent period, a critical developmental stage for social and communication skills. That is equivalent to several years in humans, suggesting the effects of a similar treatment could potentially be long-lasting, the researchers say.

Profound, prolonged effect

“We have discovered a small molecule compound that shows a profound and prolonged effect on autism-like social deficits without obvious side effects, while many currently used compounds for treating a variety of psychiatric diseases have failed to exhibit the therapeutic efficacy for this core symptom of autism,” said Zhen Yan, PhD, professor in the Department of Physiology and Biophysics in the Jacobs School of Medicine and Biomedical Sciences at UB, and senior author on the paper.

The study builds on her previous research from 2015. That work revealed how the loss of Shank 3 disrupts neuronal communications by affecting the function of the NMDA (n-methyl-D-aspartate) receptor, a critical player in regulating cognition and emotion, leading to deficits in social preference that are common in ASD.

In the new research, the UB scientists found they could reverse those social deficits with a very low dose of romidepsin, which, they found, restores gene expression and function using an epigenetic mechanism, where gene changes are caused by influences other than DNA sequences. Yan noted that human genetics studies have suggested that epigenetic abnormalities likely play a major role in ASD.

To pursue these promising findings, Yan has founded a startup company called ASDDR, which was awarded a Small Business Technology Transfer grant from the National Institutes of Health last summer for more than $770,000.

Epigenetics in ASD

Many of the mutations in ASD, Yan explained, result from chromatin remodeling factors, which are involved in dynamically changing the structure of chromatin, the complex of genetic material in the cell nucleus that condenses into chromosomes.

“The extensive overlap in risk genes for autism and cancer, many of which are chromatin remodeling factors, supports the idea of repurposing epigenetic drugs used in cancer treatment as targeted treatments for autism,” said Yan.

She and her colleagues knew that chromatin regulators — which control how genetic material gains access to a cell’s transcriptional machinery — were key to treating the social deficits in ASD, but the challenge was to know how to affect key risk factors at once.

“Autism involves the loss of so many genes,” Yan explained. “To rescue the social deficits, a compound has to affect a number of genes that are involved in neuronal communication.”

To do so, the team turned to a type of chromatin remodeler called histone modifiers. They modify proteins called histones that help organize genetic material in the nucleus so gene expression can be regulated. Since many genes are altered in autism, the UB scientists knew a histone modifier might be effective.

Loosening up chromatin

In particular, they were interested in histone deacetylase (HDAC), a family of histone modifiers that are critically involved in the remodeling of chromatin structure and the transcriptional regulation of targeted genes.

“In the autism model, HDAC2 is abnormally high, which makes the chromatin in the nucleus very tight, preventing genetic material from accessing the transcriptional machinery it needs to be expressed,” said Yan. “Once HDAC2 is upregulated, it diminishes genes that should not be suppressed, and leads to behavioral changes, such as the autism-like social deficits.”

But the anti-cancer drug romidepsin, a highly potent HDAC inhibitor, turned down the effects of HDAC2, allowing genes involved in neuronal signaling to be expressed normally.

 “The HDAC inhibitor loosens up the densely packed chromatin so that the transcriptional machinery gains access to the promoter area of the genes; thus they can be expressed,” Yan said.

The rescue effect on gene expression was widespread. When Yan and her co-authors conducted genome-wide screening at the Genomics and Bioinformatics Core at UB’s New York State Center of Excellence in Bioinformatics and Life Sciences, they found that romidepsin restored the majority of the more than 200 genes that were suppressed in the autism animal model they used.

“The advantage of being able to adjust a set of genes identified as key autism risk factors may explain the strong and long-lasting efficacy of this therapeutic agent for autism,” Yan explained. She and her colleagues will continue their focus on discovering and developing better therapeutic agents for autism.  

Full study:-  

Social deficits in Shank3-deficientmouse models of autism are rescued by histone deacetylase (HDAC) inhibition

HDAC Inhibitors

HDIs have a long history of use in psychiatry and neurology as mood stabilizers and anti-epileptics. More recently they are being investigated as possible treatments for cancers, parasitic and inflammatory diseases. 

HDAC inhibitors have effects on non-histone proteins that are related to acetylation. HDIs can alter the degree of acetylation of these molecules and, therefore, increase or repress their activity.

“To carry out gene expression, a cell must control the coiling and uncoiling of DNA around histones. This is accomplished with the assistance of histone acetyl transferases (HAT), which acetylate the lysine residues in core histones leading to a less compact and more transcriptionally active chromatin, and, on the converse, the actions of histone deacetylases (HDAC), which remove the acetyl groups from the lysine residues leading to the formation of a condensed and transcriptionally silenced chromatin. Reversible modification of the terminal tails of core histones constitutes the major epigenetic mechanism for remodeling higher-order chromatin structure and controlling gene expression. HDAC inhibitors (HDI) block this action and can result in hyperacetylation of histones, thereby affecting gene expression.^[5][6][7] The open chromatin resulting from inhibition of histone deacetylases can result in either the up-regulation or the repression of genes.”

Pitt Hopkins Research

We saw that transcription factor TCF4 (the Pitt Hopkins gene) is also lacking in some MR/ID and schizophrenia. We saw in an earlier post that TCF4 can be upregulated by PKA (protein kinase A) and that this can be achieved using a PDE4 inhibitor as used to treat asthma and COPD. So in theory Daxas should help.

The lack of the TCF4 protein in Pitt Hopkins causes a cascade of other genes to be miss-expressed. The logical thing to do is to correct that miss-expression. 

The Shank3 research is not the first to suggest that HDAC inhibition as a potentially viable therapy. In 2016 the same idea was suggested for Pitt Hopkins and while this is a rare condition, milder dysfunctions of the same TCF4 gene are seen as common in MR/ID and indeed in schizophrenia. So HDAC inhibition may be a viable therapy for many people.

HDACi meds may reverse effects of Pitt Hopkins

In a paper published this week by the journal Cell Reports, Sweatt and his colleagues at the University of Alabama at Birmingham (UAB) report that mice deficient in Tcf4 exhibit impairments in social interaction, vocalization, learning and memory characteristic of PTHS.

The impairments were “normalized” when the mice were given small-molecule drugs called HDAC inhibitors, which alter Tcf4-associated gene expression in the brain. The finding suggests that “broadly acting, epigenetically targeted therapeutics … might be particularly beneficial in PTHS patients,” the researchers concluded.

“We are quite excited by these findings, said Sweatt, a Vanderbilt University-trained pharmacologist who formerly chaired the Department of Neurobiology and directed the McKnight Brain Institute, both at UAB.

“Pitt-Hopkins Syndrome is an orphan disease that has not been extensively studied,” he said. “Having identified one potential avenue for possible therapeutics is an important step forward.”

http://www.cell.com/cell-reports/fulltext/S2211-1247(16)31036-1

“Nearly one-quarter of the genes dysregulated in the Tcf4(+/−) mice are also regulated by HDAC inhibition. The strong negative correlation between Tcf4(+/−) and CI-994 DEGs (R² = 0.72) suggests HDAC inhibition is a viable avenue for correcting a large percentage of transcriptional dysregulation associated with Tcf4 haploinsufficiency.”

Which HDAC Inhibitor?

It should be noted that Romidepsin inhibits both HDAC1 and HDAC2.

There are HDACs numbered 1 through 10.

HDAC inhibitors vary in potency. Below is a chart comparing different HDI drugs in the activation of HIV expression.

In vitro activation of HIV expression by HDAC inhibitors in an in vitro latency model.

  

The role of diet

I know that many readers of this blog like dietary interventions and do not like drugs.

In cancer I think diet can be preventative rather than therapeutic or curative. Once cancer takes hold you need very potent therapies.

In dementia it looks like diet can be preventative and therapeutic.

In mild ADHD and mild autism it looks like dietary intervention can be sufficient.  

Many flavonoids have mild epigenetic properties. They are unlikely to be potent enough to halt the cascade of changes seen in a runaway cancer, but they may well be chemoprotective, i.e. they prevent cancer developing in the first place.

Since in some autism we only need a relatively mild  effect perhaps flavonoids do have some potential, depending on which genes are miss expressed.

Epigenetic activities of flavonoids in the prevention and treatment of cancer

Food containing high amounts of epigenetically active flavonoids

Description	Class	Flavonoid	Ǿ mg/100 g	Sources of data
Grapefruit, raw (not specified as to colour) (Citrus paradisi)	Flavanones	Hesperetin	1.50	aUSDA Database for the Flavonoid Content of Selected Foods: e.g. [193]
		Naringenin	53.00
	Flavonols	Kaempferol	0.40
		Quercetin	0.50
Onions, red, raw	Flavones	Apigenin	0.24	aUSDA Database for the Flavonoid Content of Selected Foods: e.g. [193, 194, 195, 196]
		Luteolin	0.16
	Flavonols	Kaempferol	0.70
		Myricetin	2.16
		Quercetin	39.21
Soybeans, mature seeds, raw (all sources)	Isoflavones	Daidzein	62.07	bUSDA Database for the Isoflavone Content of Selected Foods: e.g. [197, 198, 199, 200, 201, 202]
		Genistein	80.99
Spices, parsley, dried (Petroselinum crispum)	Flavones	Apigenin	4503.50	aUSDA Database for the Flavonoid Content of Selected Foods: e.g. [196]
		Luteolin	19.75
Strawberries (including frozen unsweetened strawberries)	Flavonols	Fisetin	16	[203]
		Kaempferol	0.49	aUSDA Database for the Flavonoid Content of Selected Foods: e.g. [204, 205]
		Myricetin	0.35
		Quercetin	0.46
Cacao beans	Flavan-3-ols	(+)-Catechin	88.45	aUSDA Database for the aFlavonoid Content of Selected Foods: e.g. [206]
		(−)-Epicatechin	99.18
Tea, black, brewed, prepared with tap water	Flavan-3-ols	(+)-Catechin	1.51	aUSDA Database for the Flavonoid Content of Selected Foods: e.g. [196, 207, 208, 209]
		(−)-Epigallocatechin 3-gallate	9.36
	Flavonols	Kaempferol	1.41
		Myricetin	0.45
		Quercetin	2.19
Tea, green, brewed, decaffeinated	Flavan-3-ols	(−)-Epigallocatechin 3-gallate	26.05	aUSDA Database for the Flavonoid Content of Selected Foods:
	Flavonols	Kaempferol	1.00
		Myricetin	1.00
		Quercetin	2.77

A good example is EGCG 

In earlier posts on EGCG, being trialed in Spain on Down Syndrome and Fragile X; I was intrigued by the its long-lasting effects: 

Green tea extract 'boosts mental ability' in people with Down's

For most of the tests (21 of 24) there were no differences between the groups. 

However, in three tests people who'd taken EGCG did better. This improvement lasted for six months after the study ended. 

Another example is Sulforaphane (sometimes)

It appears that some people taking sulforaphane experience disease changing results, which are likely caused by the epigenetic effects of inhibiting HDAC. 

Sulforaphane from Broccoli Reduces Symptoms of Autism: A Follow-up Case Series from a Randomized Double-blind Study

Summarized Case Reports

A.    Three participants who took SF did not appear to improve during the study. Their parents reported lack of a noticeable effect and were not aware whether their young adults had been taking SF or placebo.

B.     One participant no longer uses SF. However, he improved dramatically while taking it during the study and remained “improved” after the study, suggesting to the study team a possible “epigenetic switch” might have been triggered.

“W is doing fantastic. He really turned into the most relaxed and fantastic child (on sulforaphane). Definitely something great. Helped him a lot. His friends, family, and members at his home all noticed a wonderful change. He is off the sulforaphane and has been since the end of his study in 2012.”

  

Perhaps Butyrate?  

Butyrate, Neuroepigenetics and the Gut Microbiome: Cana High Fiber Diet Improve Brain Health?

As interest in the gut microbiome has grown in recent years, attention has turned to the impact of our diet on our brain. The benefits of a high fiber diet in the colon have been well documented in epidemiological studies, but its potential impact on the brain has largely been understudied. Here, we will review evidence that butyrate, a short-chain fatty acid (SCFA) produced by bacterial fermentation of fiber in the colon, can improve brain health. Butyrate has been extensively studied as a histone deacetylase (HDAC) inhibitor but also functions as a ligand for a subset of G protein-coupled receptors and as an energy metabolite. These diverse modes of action make it well suited for solving the wide array of imbalances frequently encountered in neurological disorders. In this review, we will integrate evidence from the disparate fields of gastroenterology and neuroscience to hypothesize that the metabolism of a high fiber diet in the gut can alter gene expression in the brain to prevent neurodegeneration and promote regeneration.

  

Butyrate enhances mitochondrial function during oxidative stress in cell lines from boys with autism

In general, these data suggest that BT can enhance mitochondrial function in the context of physiological stress and/or mitochondrial dysfunction, and may be an important metabolite that can help rescue energy metabolism during disease states. Thus, insight into this metabolic modulator may have wide applications for both health and disease since BT has been implicated in a wide variety of conditions including ASD. However, future clinical studies in humans are needed to help define the practical implications of these physiological findings.

Conclusion

Clearly HDAC inhibitors are beneficial in some cancer and some autism.

In cancer the dose required is so high there almost inevitably will be some side effects, particularly in people already in poor health.

Hopefully when Dr Yan moves on to trial Romidepsin in her second mouse model, the BTBR model, she will be as successful as with the Shank3 model.

Ultimately, I assume she will trial her low dose Romidepsin as a single dose in humans. I am sure plenty of people will be interested in that, including all the Pitt Hopkins families. Hopefully someone will trial Daxas in Pitt Hopkins (upregulate PKA which then upregulates TCF4).

Dietary HDAC inhibitors include butyrate and sulforaphane. They are much weaker than Romidepsin. Would a very large dose of sulforaphane/butyrate have the potency of a small dose of Romidepsin?

To be effective in autism the HDAC inhibitor would have to freely cross the blood barrier, clearly drugs used to treat brain cancer tick this box.

Vorinostat/Zolinza also looks interesting.

We should not overlook Valproic acid, another HDAC inhibitor. This epilepsy drug can cause autism when taken during pregnancy, but is taken by some children with autism. Unlike Romidepsin and Vorinostat, which are hugely expensive, Valproic acid is cheap.

Continued use of Valproic acid can cause side effects, as seen in the comments section of this blog. A short sharp shock with valproic acid might be different.

I am sure Dr Yan chose Romidepsin for its potency. A small dose of Romidepsin is likely much more effective than a bucket load of broccoli sprouts (sulforophane).  

Just how low a dose is Dr Yan talking about? Recall that Professor Catterall’s  low dose of clonazepam (to modulate alpha3 subunits of GABAa receptors) was so low in humans it has none of the well-known drawbacks of benzodiazepine use (addiction, tolerance etc).

Dr Naviaux’s use of Suramin was long thought to be impractical in humans due to side effects, but now this appears not to be the case.

Back to Dr Yan:- 

Social deficits in Shank3-deficient mouse models of autism are rescued by histone deacetylase (HDAC) inhibition

Treatment with the HDAC inhibitor romidepsin lastingly relieves autism-like social deficits in Shank3-deficient mice. The level of global H3 acetylation (Fig. 1a) in the frontal cortex of Shank3+/ΔC mice was significantly lower than that from wild-type (WT) mice. 

 A systemic administration of low-dose romidepsin (0.25 mg/kg, intraperitoneally (i.p.), once daily for 3 d), a highly potent and brainpermeable class I-specific HDAC inhibitor (with nanomolar in vitro potency25) approved by the US Food and Drug Administration (FDA) for cancer treatment26–28, significantly elevated the level of acetylated H3 in Shank3+/ΔC mice, while it had little effect in WT mice. These data suggest that Shank3-deficient mice have an abnormally low level of histone acetylation, which can be restored by romidepsin treatment. 

This dose looks like about one tenth of the used in mice in cancer trials.

In humans, Romidepsin is for intravenous infusion only. Each 10 mg single-use vial of Romidepsin/Istodax costs about $2,800.

Vorinostat/Zolinza costs about $3,800 for 30 capsules.

If the autism effects of a potent HDAC1/2 inhibitor can last for several years in humans, as suggested by Dr Yan, and if the dose is a tenth of the cancer dose, the cost would not seem to be such a barrier.

The open question is the safety profile of Romidepsin at a single low dose in otherwise physically healthy children.

Risk vs Reward

While nobody wants side effects, one has to consider the risk versus the reward. In some single gene types of severe autism it is clear what the outcome with no intervention will be; perhaps that looming outcome warrants taking a bigger risk than someone with mild autism struggling with social difficulties? But then again, perhaps an HDAC1/2 inhibitor might improve social functioning so someone with Asperger’s, or indeed schizophrenia, does not commit suicide?