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The psychedelic experience: comparing LSD, ketamine and nitrous oxide 

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Why does MDMA cause a hangover, but psilocybin and LSD Don’t?

A team of researchers have found that patterns of activity in the brain associated with nitrous oxide, ketamine and LSD overlap, suggesting a common underlying biology.

Michigan Psychedelic Center researchers, George Mashour, M.D., Ph.D. and Richard Harris, Ph.D., at the University of Michigan Medical School, have conducted a study investigating the neurobiology of psychedelic experiences.

To investigate whether or not the neurobiology of the psychedelic experience was similar across substances, the team used fMRI to examine the brain activity of healthy people who were administered nitrous oxide, then compared this to data collected from participants in different studies who were given ketamine and LSD.

This data was also compared to a control group comprised of participants administered propofol, a commonly used anaesthesia drug, to distinguish between brain changes not related to the psychedelic experience.

Brain connectivity

In their paper, ‘Classical and non-classical psychedelic drugs induce common network changes in human cortex’, published in the journal NeuroImage, the team state that participants under the influence of each psychedelic drug had decreased connectivity within a particular network.

However, they also had increased connectivity across various networks. 

They note that although there were differences, each psychedelic increased connectivity between the right temporoparietal junction and intraparietal sulcus in both hemispheres of the brain, and between the precuneus and left intraparietal sulcus.

These nodes are located in the so-called cortical “hot zone” of the brain, an area proposed to be critical for determining the content of conscious experience, they add, and that this could help explain the altered states of consciousness described by people administered these psychedelic substances.

See also  Study explores action of ketamine as antidepressant in chronic pain

The researchers suggest that the overlapping patterns of activity between the substances could point to a common underlying biology, and that additional research to determine the specifics of this biology could help researchers determine how best to use psychedelics as therapeutics.

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Markets & Industry

Compass, Transcend, and Usona Identified as Receivers of Priority Vouchers Following Psychedelics Executive Order

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Compass Pathways, Transcend Therapeutics, and the Usona Institute have been named the first recipients of FDA National Priority Vouchers following last week’s landmark executive order, for programs developing psilocybin and methylone, an MDMA analog.

“These medications have the potential to address the nation’s mental health crisis, including conditions like treatment-resistant depression, alcoholism and other serious mental health and substance abuse conditions,” said FDA Commissioner Marty Makary, M.D., M.P.H.

Issued by President Trump on April 18, the “Accelerating Medical Treatments for Serious Mental Illness” order directed the FDA to provide these high-value regulatory tools to designated breakthrough therapies. By securing these vouchers, the three organizations are now positioned to shave months off the typical regulatory review timeline, significantly shortening the path to commercialization for their lead candidates.

The vouchers, known as Priority Review Vouchers (PRVs), are powerful regulatory assets that grant the holder a fast-track review from the FDA by reducing the target review time from ten months to six. Originally designed to incentivize development in rare pediatric or tropical diseases, their application to psychedelics marks a strategic shift in federal policy. 

Compass Pathways appears to be the closest to utilizing this advantage. Recent Phase 3 data for its lead compound, COMP360 (synthetic psilocybin), demonstrated a “highly statistically significant” antidepressant effect in patients with treatment-resistant depression (TRD). 

The company was the first to confirm being a recipient of one of the three vouchers, via a press release published Friday.  

According to CEO Kabir Nath, the company is potentially the first to bring a classic psychedelic to market, with a rolling NDA submission already underway. Compass expects to complete its filing by the second half of 2026.

See also  First-ever Phase 3 trial investigating psilocybin for depression launches

The remaining two organisations to receive the vouchers were not identified by the FDA on its release, but can be deducted from the information provided by the agency, as the only two working in late stage trials with the compounds targeted by the measure.

Transcend Therapeutics’ voucher comes at a pivotal moment in its corporate evolution. The New York-based firm was recently acquired by Japanese pharmaceutical giant Otsuka in a deal worth up to $1.2 billion, and is developing a pipeline for methylone, a non-hallucinogenic analog of MDMA. By focusing on neuroplasticity without the intense cognitive alterations associated with classic MDMA, Transcend is targeting a unique regulatory niche for PTSD. 

Finally, the Usona Institute—a non-profit medical research organization—continues its push for psilocybin as a treatment for Major Depressive Disorder (MDD). Unlike its commercial counterparts, Usona’s receipt of the voucher underscores the administration’s intent to support diverse research models, including non-profit institutes. Usona is currently conducting its “uAspire” Phase 3 trial, which evaluates a single 25mg dose of psilocybin. The voucher ensures that once Usona completes its trial work, the resulting data will receive the highest level of federal priority, ensuring that patient access is not delayed by administrative bottlenecks.

Interestingly, ibogaine was not targeted for the fast-track measure in spite of being a central protagonist of the executive order’s announcement last week by the White House.

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Europe’s Regulatory Body Signals Shift To ‘Weight of Evidence’ Model For Drug Approvals—How Does It Affect Psychedelic Medicines?

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The European Medicines Agency is taking steps to rethink how certain high-need medicines reach patients, with a new concept paper proposing a more flexible, evidence-based pathway for cancer therapies. While the focus is paediatric oncology, the implications may extend far beyond cancer, raising questions about whether similar approaches could eventually support the development of psychedelic treatments.

The “Weight of Evidence” Model

Published last month, the EMA’s concept paper outlines plans for a reflection paper on how “proof-of-concept” data should be used to guide early-stage drug development. At its core is a shift away from rigid data requirements toward a “weight of evidence” model, where regulators assess the totality of available data, including non-clinical studies, early clinical signals, and biological rationale.

This approach is already gaining traction in oncology, particularly in paediatric settings where patient populations are small and traditional large-scale trials are often unfeasible. In such cases, regulators are increasingly willing to rely on mechanistic understanding and preclinical evidence to justify moving into clinical trials earlier, provided there is a strong scientific rationale and unmet medical need.

The EMA’s concept paper emphasises that development decisions should be grounded in several key domains, including mechanism of action, disease biology, pharmacology, and safety, as well as the broader clinical context. Rather than requiring exhaustive datasets upfront, the agency is signalling openness to iterative development, where evidence is built progressively and regulatory decisions evolve alongside the data.

For the psychedelics field, this raises a clear question: could a similar framework accelerate the path to approval?

See also  World’s first DMT-assisted therapy trial successfully completes first phase

A shift toward mechanism-of-action–based regulation in psychedelics could, in theory, reduce the need to pursue separate approvals for each diagnostic category, such as depression or PTSD, by anchoring use to a shared underlying biology.

If regulators accept that psychedelic therapies exert their primary effect through defined pathways, for example 5-HT2A receptor activation leading to increased neuroplasticity and network-level brain changes, then the relevant treatment population could be framed around patients exhibiting that dysfunction rather than a specific DSM label. In this model, a single approval could cover multiple conditions where the same mechanism is implicated, provided there is sufficient evidence linking that pathway to clinical benefit across those populations.

This would shift development away from duplicative, indication-by-indication trials toward demonstrating consistent mechanistic effects and reproducible outcomes in biologically defined subgroups.

There are other parallels between the regulatory paths described in the paper and psychedelics. Psychedelic therapies are often being developed for conditions where unmet need remains high and patient populations can be difficult to study using conventional trial designs. Like paediatric oncology, these indications may benefit from more flexible approaches that incorporate multiple forms of evidence.

However, important differences remain.

Oncology drug development is underpinned by well-established biological models and biomarkers, allowing regulators to link mechanism of action to clinical outcomes with a relatively high degree of confidence. In contrast, the mechanisms underlying psychedelic therapies are still being defined, spanning pharmacological effects, neural network changes, and the subjective therapeutic experience itself.

The EMA’s framework places significant weight on the relevance and reliability of non-clinical models, an area where psychedelics currently face limitations. Translating findings from animal studies to complex psychiatric outcomes in humans remains a challenge, and there is no widely accepted biomarker that can serve as a proxy for therapeutic response.

See also  Ketamine’s therapeutic benefits go beyond depression, say researchers

Endpoints also differ. Cancer trials can rely on objective measures such as tumour progression or survival, whereas psychedelic studies typically depend on subjective scales and patient-reported outcomes. This makes it more difficult to integrate different sources of evidence into a unified regulatory decision.

Even so, the direction of travel is notable. By formalising a weight-of-evidence approach and emphasising mechanism-driven development, the EMA is signalling greater flexibility in how innovative therapies are assessed. If these principles are applied more broadly across therapeutic areas, they could eventually lower some of the structural barriers facing psychedelic drug development.

For now, the concept paper remains focused on oncology, and significant scientific and regulatory hurdles would need to be addressed before such a model could be extended to psychedelics. But as regulators continue to adapt to emerging forms of medicine, the boundaries between therapeutic areas may become less rigid.

In that context, the EMA’s latest move may not just reshape cancer drug development, but also offer an early glimpse of how the next generation of psychiatric treatments could be evaluated.

Picture: EMA headquarters in Amsterdam. Courtesy of EMA.

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News

Quit Smoking: Psilocybin Found To Be 6 Times More Effective Than Nicotine Patches

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A new clinical trial has found that psilocybin-assisted therapy may be better at helping people stop smoking than standard nicotine replacement treatment.

The results were published on March 10, 2026 in the journal JAMA Network Open. Researchers from Johns Hopkins University and University of Alabama at Birmingham conducted a randomized clinical trial comparing a single psilocybin session combined with therapy to nicotine patch treatment with the same therapy program.

Smoking remains one of the leading causes of preventable disease and death worldwide. While existing treatments such as nicotine replacement therapy can help some people quit, long term success rates are often limited. The study aimed to test whether a psychedelic assisted approach could improve those outcomes.

The Trial

The trial included 82 adults who smoked tobacco daily and wanted to quit. Participants were randomly assigned to one of two groups. One group received a program built around a single high dose of psilocybin alongside structured psychological support. The other group received nicotine patches together with the same therapy sessions.

Both groups took part in a 13 week cognitive behavioral therapy program designed to help people stop smoking. This allowed researchers to compare the effect of psilocybin directly against the standard nicotine patch treatment while keeping the psychological support constant.

Participants in the psilocybin group took one oral dose of the compound, calculated at 30 milligrams per 70 kilograms of body weight. The session took place in a controlled setting with trained guides present. The experience was integrated into the broader therapy program, which included preparation sessions before the dose and follow up meetings afterwards.

See also  Phase 2 clinical trial to investigate psilocybin for anorexia nervosa 

Six months after treatment, the difference between the two groups was clear: around 40.5 percent of people who received psilocybin were able to remain abstinent from smoking. In the nicotine patch group, 10 percent achieved the same result.

This means that the group receiving psilocybin treatment was six times more likely to not pick up smoking at six months from the initial treatment date.

Researchers used biological tests to confirm whether participants had stopped smoking. These tests measured markers in breath and blood that indicate tobacco use. This approach allowed the team to verify the results rather than relying only on self reported behavior.

The authors note that smoking cessation is a difficult challenge for many people, even when treatment is available. Relapse is common, and many smokers attempt to quit several times before succeeding. The study suggests that psychedelic assisted therapy may offer a new approach by combining psychological support with a single powerful therapeutic experience.

However, the researchers also describe the trial as a pilot study. The relatively small number of participants means that larger studies will be needed to confirm the findings and better understand how the treatment works.

Several psilocybin therapies are advancing through the clinical pipeline regulated by the U.S. Food and Drug Administration. The most advanced programs target treatment resistant depression and major depressive disorder in late stage trials. Earlier studies are exploring psilocybin for post traumatic stress disorder, alcohol use disorder and anxiety or depression associated with life threatening illnesses.

If the results of the nicotine trail are replicated in larger trials, psilocybin assisted therapy could also become part of a new generation of treatments for tobacco dependence. The approach differs from traditional medications by focusing on psychological change during a guided therapeutic session rather than daily drug use.

See also  Intravenous DMT formulation being developed for stroke trial

For now, the study provides early clinical evidence that psilocybin combined with therapy may significantly improve smoking cessation outcomes compared with one of the most widely used existing treatments.

Image made using AI tools.

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Psychedelic Health is a journalist-led news site. Any views expressed by interviewees or commentators do not reflect our own. We do not provide medical advice or promote the personal use of psychedelic compounds. Please seek professional medical advice if you are concerned about any of the issues raised.

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