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Study explores action of ketamine as antidepressant in chronic pain

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This is Your Brain on Ketamine

Researchers at the University of Alabama, Birmingham, say the study findings demonstrate the critical role of the protein Tiam1 in the pathophysiology of chronic pain-induced mood dysregulation, and the sustained antidepressant-like effects of ketamine.

The team says they have uncovered the underlying mechanism that drives depressive systems, which acts to cause hypersensitivity in a part of the brain called the anterior cingulate cortex (ACC).

Knowledge of this mechanism identifies a potential therapeutic target for the treatment of chronic pain-induced depression, say Lingyong Li, Ph.D., and Kimberley Tolias, Ph.D., co-leaders of the research.

See also  Study measuring ketamine’s effect on brain shows promise

Published in The Journal of Clinical Investigation, the research focused on Tiam1, which modulates the activity of other proteins that help build or unbuild the cytoskeletons of cells. 

The study revealed that chronic pain in a mouse model leads to an activated Tiam1 in ACC pyramidal neurons, resulting in an increased number of spines on the neural dendrites. Dendrites are tree-like appendages attached to the body of a neuron that receive communications from other neurons.

See also  Study looks at how ketamine acts as a switch in the brain

This higher spine density increased the number of connections, and the strength of those connections, between neurons, a change known as synaptic plasticity. Those increases caused hypersensitivity and were associated with depression in the mouse model. 

Reversing the number and strength of connections in the model, by using an antagonist of Tiam1, relieved the mice of depression and diminished hypersensitivity of the neurons.

The study

To show that Tiam1 in the ACC modulates chronic pain-induced depressive-like behaviours, the researchers used molecular scissors to delete Tiam1 from the forebrain excitatory neurons of the mice. 

These mice were viable, and fertile, and displayed no gross alterations, and they still showed hypersensitivity to chronic pain. However, these Tiam1 conditional knockout mice did not display depressive- or anxiety-like behaviours in five different tests that gauge depression or anxiety.

When researchers specifically deleted Tiam1 from ACC neurons, they found the same results as the broader forebrain deletion, demonstrating that Tiam1 expressed in ACC neurons appears to specifically mediate chronic pain-induced depressive-like behaviours.

Other studies have established that an underlying cause of stress-induced depression and anxiety disorders is alterations in synaptic connections in brain regions involved in mood regulation, including the prefrontal cortex, the hippocampus and the amygdala. 

Li and Tolias found similar changes in dendritic neurons in the ACC for chronic pain-induced depressive-like behaviour — they saw a significant increase in dendritic spine density and signs of increased cytoskeleton building. 

This was accompanied by increased NMDA receptor proteins and increased amplitudes of NMDA currents in the ACC neurons, both associated with hyperactivity. These maladaptive changes were not seen in the Tiam1-knockout mice.

Researchers further showed that inhibiting Tiam1 signalling with a known inhibitor alleviated the chronic pain-induced depressive-like behaviours, without reducing the chronic pain hypersensitivity itself. 

The inhibition also normalised dendritic spine density, cytoskeleton building, NMDA receptor protein levels and NMDA current amplitudes.

Ketamine is a drug known to produce rapid and sustained antidepressant-like effects in chronic pain-induced depression, without decreasing sensory hypersensitivity. 

However, its mechanism is not fully understood. Li, Tolias and colleagues showed that ketamine’s sustained antidepressant-like effects in chronic pain are mediated, at least in part, by ketamine’s blocking the Tiam1-dependent, maladaptive synaptic plasticity in the mouse ACC neurons.

Li, an associate professor at the University of Alabama at Birmingham Department of Anesthesiology and Perioperative Medicine, stated: “Chronic pain is a major, unmet health issue that impacts the quality of life. Unfortunately, patients suffering from chronic pain have limited effective treatment options.

“Our work demonstrates the critical role Tiam1 plays in the pathophysiology of chronic pain-induced mood dysregulation and the sustained antidepressant-like effects of ketamine, revealing it as a potential therapeutic target for the treatment of comorbid mood disorders in chronic pain.”

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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.

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?

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.

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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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.

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.

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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