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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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Landmark UK trial to investigate psilocybin for opioid addiction relapse

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For the first time, a government-funded UK trial will investigate psilocybin-assisted psychotherapy for targetting relapses associated with opioid addiction, aiming to bring an innovative new therapy to the NHS if successful. 

Research shows that the UK had the world’s highest rate of opioid consumption in 2019, amounting to a serious public health concern. Further, figures show that around 140,000 people are accessing treatment for opioid dependence in the country. Despite the prevalence of opioid addiction, there are currently limited medicines to help prevent relapses during recovery.

Led by Imperial College London, the new study will use psilocybin combined with psychological support in people who have recently undergone detoxification from opioids such as heroin, methadone or buprenorphine.

While previous research into psilocybin has shown its potential as a treatment for conditions such as depression, anxiety PTSD and addiction, this is the first trial looking at the medicine for addiction relapse.

See also  Compass Pathways launches Phase 3 psilocybin trial in UK

The study is one of four projects focused on reducing drug deaths that have been funded by the National Institute for Health and Care Research (NIHR) as part of the Addiction Healthcare Goals programme, led by the Office for Life Science (OLS). 

According to the NHIR, the programme forms part of the Department of Health and Social Care’s plan to deliver a world-class treatment and recovery system for people experiencing drug and alcohol addictions.

Dr David Erritzoe, Clinical Director and Deputy Head of the Centre for Psychedelic Research at Imperial College London, project co-lead, said in a press statement: “We know that up to 90% of people relapse back to opioid use within 12 months of finishing detox, so finding new and effective treatments is essential. 

“If this trial is successful, it offers hope for a new type of treatment that could make a significant difference to this group of people.

“If our initial trial is successful, we will work to enable the development of further clinical trials in larger populations, to bring a new treatment to patients and the NHS.”

Participants will attend Imperial’s NIHR Clinical Research Facility at Hammersmith Hospital campus to receive psilocybin-assisted psychotherapy and will receive functional MRI brain scans to enable investigation of the mechanisms of psilocybin in the brain.

Imperial has confirmed that participants will be monitored for up to six months following dosing to track any changes to their opioid use, cravings, mental health outcomes and psychological wellbeing. 

Study co-lead Dr Louise Paterson said in a press statement: “This trial will examine whether we can improve recovery in a severely under-served group of people – namely, those with opioid dependence during their most vulnerable post-detox phase. 

“Clinical studies, including those in our Centre for Psychedelic Research, have shown great promise for this type of treatment in other mental health conditions. We want to see if it works equally well for opioid use disorder.”

Professor Anne Lingford-Hughes, Chair of the Addiction Healthcare Goals, and who is also a Professor of Addiction Biology at Imperial, added: “New approaches to treat drug addiction and reduce drug-related deaths, particularly from overdose, are urgently needed. 

“The Addiction Healthcare Goals programme is pleased to fund promising innovations that have brought together partnerships between industry, academia and organisations involved in delivering treatment and care for those experiencing drug addictions.” 

Recruitment is expected to begin in Spring 2025.

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Psilocybin versus escitalopram for depression shows positive results

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Compass Pathways launches Phase 3 psilocybin trial in UK

A six-month follow-up study of a Phase 2 clinical trial investigating psilocybin versus escitalopram for the treatment of major depressive disorder has shown positive results.

Around 30% of people living with depression in the UK are resistant to current treatments, highlighting an urgent need for new therapies. As the researchers of this study highlight, even for patients who have had their depression successfully treated, there is a high risk of relapse, with one in three patients relapsing within the year.

Equally, SSRI treatments often include side effects such as sexual dysfunction, weight gain, fatigue, and emotional blunting.

The authors note that a key consideration of any treatment of major depressive disorder “is its capacity to produce sustained antidepressant response or remission.”

Mounting evidence is increasingly pointing to psilocybin-assisted therapy as an innovative new treatment for the condition, with clinical trials showing that the therapy is capable of producing rapid and long-lasting antidepressant effects.

However, while clinical trials have investigated the treatment itself, they have not compared the treatment to the current gold standard in depression medications or looked at the long-term effects of the treatment.

This Phase 2 trial is the first to compare the long-term antidepressant effects of these two treatments alongside mental health measures including work and social functioning, connectedness, and meaning in life. 

In the trial, patients with major depressive disorder recruited from a UK hospital were administered either two doses of 25mg of psilocybin along with psychological support, or a six-week course of the selective serotonin reuptake inhibitor (SSRI) escitalopram in combination with psychological support.

The findings, published in eClinicalMedicine, revealed that both administered treatments saw sustained improvements in depressive symptoms, however, patients who were administered psilocybin-assisted psychotherapy saw greater lasting improvements. 

These improvements included psychosocial functioning, meaning in life, and psychological connectedness.

Dr James Rucker, Consultant Psychiatrist & Senior Clinical Lecturer in Psychopharmacology, Institute of Psychiatry, Psychology & Neuroscience, King’s College London, said: “The authors have tended to attribute differences observed in this study to comparative differences between the drugs themselves, however, it is also possible that the results reflect biased reporting between groups. 

“This is more likely here because A) studies involving psilocybin tend to attract those with positive preconceptions about psilocybin and negative preconceptions about conventional antidepressants, and B) study participants were unblinded during the long-term follow-up phase that is reported in the paper, so knew which condition they were allocated to.

“This said, the nature of depression varies hugely between individuals, and this calls for the development of a similarly varied suite of treatment paradigms. Psilocybin therapy is certainly a different paradigm of treatment to escitalopram. 

“The observation of similar levels of effectiveness to antidepressants here is encouraging to see alongside the much larger trials of psilocybin currently underway here in the UK, Europe and the US.”

The authors write: “Key limitations of the study include its suboptimal power to detect small but meaningful differences between treatments, missing data, the potential use of additional interventions during the follow-up period, and reliance on self-reported treatment assessments. 

“These factors may affect the interpretation of the study findings and should be considered when evaluating the results.”

With these considerations in mind, the researchers suggest that the findings warrant further investigation into psilocybin-assisted psychotherapy for the treatment of depression.

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Shortwave Life Sciences psilocybin drug shows positive results in anorexia trial

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Shortwave Life Sciences psilocybin drug positive results anorexia trial

Shortwave Life Sciences has announced it has achieved a significant breakthrough in its ambitions to transform eating disorder care with positive pre-clinical results from its latest pharmacodynamics study, demonstrating the safety of its psilocybin-based drug combination for the treatment of anorexia nervosa.

Anorexia nervosa has one of the highest fatality rates. The condition is a complex mental health condition as well as a metabolic disease, yet no FDA-approved pharmacological treatments are currently available for the condition.

Shortwave Life Sciences in collaboration with Science in Action, an expert pre-clinical GLP-certified lab in Israel, has now tested the safety of buccal administration of Shortwave’s combination drug comprised of psilocybin and a beta-carboline.

The company says this novel treatment provides an expanded mechanism of action and a therapeutic effect superior to psilocybin alone, impacting more than one group of receptors in the brain.

For the study, three groups of rats were given varying doses of the combination drug (0.23ml, 0.5ml, and 1ml), with results showing no adverse effects, weight changes, or behavioural changes following the psychedelic effects.

See also  Short Wave Pharma: innovating eating disorder care with psychedelics

“This is a monumental step forward for Shortwave. Our relentless pursuit of breakthrough mental health treatments comes with the responsibility of ensuring safety at every stage,” commented Shortwave Life Sciences CEO Rivki Stern Youdkevich.

“We are proud of the positive outcomes from this rigorous pre-clinical trial, further validating our patent-pending drug combination and buccal delivery system.

“With this success, we are reaffirmed in our approach to addressing the global mental health crisis.”

In the pre-clinical pharmacodynamics study, all subjects remained healthy and unaffected during the trial, which Shortwave has stated marks a strong foundation for future clinical development.

Furthermore, no adverse events or vital sign changes were reported across all groups, and the results confirmed the safety profile for the psilocybin-based combination drug at elevated doses.

This achievement comes on the heels of the International PCT Examining Committee’s recent acknowledgment of Shortwave’s patent claims for its novel, non-obvious, and industrially applicable mucoadhesive buccal film.

Designed for rapid absorption and bypassing liver and gut degradation, the platform holds transformative potential for patients facing metabolic and psychiatric challenges. This method of administration is designed to be sensitive to patient needs, who may not want to swallow the medicine, and also provides higher bioavailability.

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