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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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Psilocybin analogue shows positive results in Phase 2 depression study

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Psilocybin analogue shows positive results in Phase 2 depression study

Cybin has announced positive Phase 2 topline safety and efficacy data for its proprietary deuterated psilocybin analogue – CYB003 – for the treatment of major depressive disorder (MDD).

Results from Cybin’s study have shown that 79% of patients were in remission from depression at six weeks after receiving two doses of CYB003.

CYB003 demonstrated a large improvement in symptoms after one dose and a total of 79% of patients were responsive to the treatment. The compound also demonstrated an excellent safety profile in doses tested, with all reported adverse events mild to moderate and self–limiting.

Additionally, Cybin has stated that the magnitude of improvement was superior compared to approved antidepressants and recently reported data with other psychedelics, stating that the effects translate into an unprecedented effect size.

The company has said that the results compare favorably to pooled data from 232 industry studies of current standard-of-care antidepressants, SSRIs, submitted to the FDA.

The announcement follows Phase 2 interim results in early November 2023, which demonstrated that CYB003 saw a “rapid, robust and statistically significant reduction in symptoms of depression three weeks following a single 12mg dose compared to placebo”.

Cybin CEO, Doug Drysdale, stated: “We are delighted to share that CYB003 achieved the primary efficacy endpoint in this study and showed rapid and statistically significant improvements in depression symptoms after a single dose, with a clear incremental benefit of a second dose, resulting in four out of five patients in remission from their depression at six weeks.

“This is an impressive finding and follows on from the unprecedented interim results we announced earlier this month.”

Drysdale emphasised that the strength of the data will support CYB003 into Phase 3 of the study.

Cybin CMO, Amir Inamdar, added: “The significant reduction in depression symptoms observed in our Phase 2 study is highly gratifying.

“At the three-week primary efficacy endpoint, a single 12mg dose of CYB003 showed a rapid, robust, and highly statistically significant improvement in depression symptoms compared to placebo, with a -14.08 point difference in change from baseline in MADRS. 

“This translated into a very large effect size. Similar significant and robust effects were also seen with a single 16mg dose, which resulted in an improvement in symptoms of depression as measured using the MADRS total score by about 13 points versus placebo. 

“These effects were evident on day one with the 16mg dose and were also highly statistically significant. When data from 12mg and 16mg are pooled, these robust effects are maintained. Further, with two doses, response and remission rates in excess of 75% were observed with CYB003 (12mg). 

“With these findings in hand, we are encouraged by the potential of CYB003 to help those with MDD and look forward to progressing to a multinational, multisite Phase 3 study early next year.”

Cybin is planning on submitting topline data to the FDA with an aim to hold a Phase 2 meeting in Q1 of 2024, with further 12-week durability data from Phase 2 CYB003 expected in Q1, and recruitment for the Phase 3 study anticipated to begin by the end of Q1 2024.

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Clerkenwell Health calls for volunteers to support groundbreaking psychedelic research

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Clerkenwell Health calls for volunteers to support groundbreaking psychedelic research

Mental health research provider Clerkenwell Health is calling for volunteers to join its groundbreaking clinical trials that will research whether psychedelics can provide effective treatments for complex mental health conditions.

Clerkenwell is seeking a diverse group of volunteers from across the UK between 18 and 65 years old to take part in the trials if they suffer from a relevant condition. 

The trials, which will be conducted at Clerkenwell Health’s purpose-built facility near Harley Street in London, are being run in partnership with a number of world-leading drug developers to test whether psychedelic drugs – often combined with talking therapy – can offer a new approach to treating a variety of mental health illnesses.

See also  Clerkenwell Health is launching a free UK psychedelic therapist training programme

Clerkenwell Health is seeking volunteers for trials that look to find cures for a range of conditions, including PTSD, depression, alcohol use disorder and anorexia. 

Many of the conditions have few successful treatment options and Clerkenwell’s innovative methods of combining psychedelics with therapy aim to to treat these problems more holistically, providing long-term quality of life for patients.

Chief Scientific Officer at Clerkenwell Health, Dr Henry Fisher, said: “With the current system for treating mental health disorders simply not working, we’re calling for patients to help identify the next wave of treatments. 

“These have the potential to be groundbreaking for the millions of people across the UK who are affected by poor mental health.

“The status quo for mental health treatment has not only resulted in patients experiencing debilitating side-effects, huge waiting lists and high relapse rates, but is costly, complicated and broadly ineffective. 

“By participating in upcoming clinical trials, patients have an opportunity to make a valuable contribution to growing research which will support the development of the next generation treatments for mental health conditions.”

According to MIND, approximately 1 in 4 people in the UK will be affected by a mental health condition each year and with a significant rise in people contacting mental health services in recent years, there has never been a more desperate need to identify new and innovative treatments.

Given the challenges facing the country’s health service and with mental health challenges on the rise, the search for volunteers to test effective treatments has never been more pressing. 

Clerkenwell has stated, in this regard, that it has gone national with its search for volunteers in an effort to deliver medical breakthroughs in mental health akin to the Polio clinical trials in the 20th Century.

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Paper explores extended difficulties following psychedelic trips

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Paper explores extended difficulties following psychedelic trips

A new paper has explored the extended difficulties experienced by some people following psychedelic drug use and discusses psychedelic harm reduction.

While multiple studies have shown that psychedelics can be safe when administered appropriately, some people experience difficulties following their use. These difficulties can last anywhere from a few days to years.

With a rise in clinical research surrounding these compounds, there is a drive to change drug policy and several places have already implemented progressive approaches to accessing these therapies such as decriminalisation or including them on authorised medical access schemes. 

In light of these developments, it is vital to understand the potential risks associated with psychedelic use and what actions can be taken to reduce these risks.

The paper has been published in Plos One and authored by a team of leading psychedelic scientists from the Universities of Exeter, Greenwich and Queen Mary, University College London and Royal Holloway, New York University and the Perception Restoration Foundation.

Extended difficulties following psychedelic use

The team of researchers has gathered data on the context of use, nature and duration of these difficulties and explored risk factors and perceived causes that may contribute to these experiences. 

The most common forms of extended difficulty that the team uncovered include symptoms such as anxiety/fear and existential struggle, as well as social disconnection, depersonalisation and derealisation.

“For approximately one-third of the participants, problems persisted for over a year, and for a sixth, they endured for more than three years,” the authors write.

The findings revealed that the length of time these experiences last following psychedelic use could be predicted by the participants’ knowledge of dose and drug type, and that the experiences were shorter if a participant had taken part in a guided psychedelic experience. 

Additionally, the most common length of time such difficulties lasted was between one and three years. When asked about mental illness onset following the psychedelic experience, 18.8% said they had gone on to be diagnosed with a mental illness, while 76.8% said they had not.

The authors write: “Our findings support the results of Simonsson et al., who found that anxiety was the most common enduring difficulty, based on quantitative questionnaire data and Bouso et al’s study of the Global Ayahuasca Survey, in which ‘feeling nervous, anxious or on edge’ was the second most common adverse mental health effect. Our findings also suggest that a Sense of disconnection from others was within the top five most prevalent themes, as did the studies by Simonsson et al. and Bouso et al. 

“Some extended adverse effects that were quite common in other studies weren’t so common in our data set–for example, feeling a harmful connection to the spirit world was reported by 14% of respondents to the Global Ayahuasca Survey but by less than 4% of our data set, which may suggest some forms of difficulty are particularly associated with certain psychedelic substances and/or their associated cultures.”

Reducing risk factors

The authors suggest a number of actions that could be taken to reduce these risks.

Highlighting that, as anxiety and fear are some of the most commonly reported difficulties, the authors suggest that all legal psychedelic experience providers give guidance on methods for “self-soothing and overcoming bouts of anxiety following the retreat, clinical trial or ceremony.”

Further suggestions include informing participants of potential harms and risks and advising participants that the integration process may take some time, and what practices can be done to help people cope with difficulties. The authors say these practices will be explored in an upcoming paper.

The team writes: “We envisage using the information in this study, and accompanying future papers that focus on social support and forms of coping used by those with enduring difficulties, to provide structured guidance and training to psychedelic retreats, therapists and clinical trial centers about the potential for adverse experiences, what the potential risk factors are and what can be done to help individuals who report such extended difficulties.”

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