Psilocybin history, action and reaction: A narrative clinical review

Mechanisms of therapeutic change after psychedelic treatment in OCD

Novel treatments are required for the 30-50% of individuals with obsessive-compulsive disorder (OCD) who remain resistant to first-line pharmacological and psychotherapeutic treatments. Recent pilot data suggest benefit from psilocybin-assisted psychotherapy (PAP) and from imagery rescripting (ImRs). We explore psychological mechanisms of change underpinning both interventions that appear to allow for reprocessing of negative emotions and core beliefs associated with past aversive events. A next critical step in PAP is the development of psychotherapeutic frameworks grounded in theory. We propose that basing PAP on an ImRs framework may provide synergistic benefits in symptom reduction, modification of core beliefs, and value-based living.

Psilocybin promotes neuroplasticity and induces rapid and sustained antidepressant-like effects in mice

BACKGROUND

Psilocybin offers new hope for treating mood disorders due to its rapid and sustained antidepressant effects, as standard medications require weeks or months to exert their effects. However, the mechanisms underlying this action of psilocybin have not been identified.

AIMS

To investigate whether psilocybin has rapid and sustained antidepressant-like effects in mice and investigate whether its potential mechanisms of action are related to promoted neuroplasticity.

METHODS

We first examined the antidepressant-like effects of psilocybin in normal mice by the forced swimming test and in chronic corticosterone (CORT)-exposed mice by the sucrose preference test and novelty-suppressed feeding test. Furthermore, to explore the role of neuroplasticity in mediating the antidepressant-like effects of psilocybin, we measured structural neuroplasticity and neuroplasticity-associated protein levels in the prefrontal cortex (PFC) and hippocampus.

RESULTS

We observed that a single dose of psilocybin had rapid and sustained antidepressant-like effects in both healthy mice and chronic CORT-exposed mice. Moreover, psilocybin ameliorated chronic CORT exposure-induced inhibition of neuroplasticity in the PFC and hippocampus, including by increasing neuroplasticity (total number of dendritic branches and dendritic spine density), synaptic protein (p-GluA1, PSD95 and synapsin-1) levels, BDNF-mTOR signalling pathway activation (BDNF, TrkB and mTOR levels), and promoting neurogenesis (number of DCX-positive cells).

CONCLUSIONS

Our results demonstrate that psilocybin elicits robust, rapid and sustained antidepressant-like effects which is accompanied by the promotion of neuroplasticity in the PFC and hippocampus.

Review of Psilocybin Use for Depression among Cancer Patients after Approval in Oregon

Despite the legalization of psilocybin therapy for depression in terminal illnesses such as advanced cancer through Oregon's Measure 109 in 2020, significant challenges have impeded its implementation. This review synthesizes the empirical data supporting the utilization of psilocybin therapy for addressing cancer-related depression, including an evaluation of its purported benefits and potential adverse effects. It provides a comprehensive examination of therapeutic strategies, dosing regimens, and barriers to ensuring responsible and equitable access. Salient issues explored include the development of ethical protocols, integration within healthcare systems, ensuring statewide availability, resolving legal ambiguities, and defining clinical standards. Oregon's pioneering role serves as a case study, highlighting the necessity of addressing regulatory, logistical, and ethical obstacles to ensure the establishment of rigorous and equitable psilocybin care models.

Trips Through the Skin: Reviewing Cutaneous Drug Reactions to Psychedelics and Hallucinogens

Although psychedelic and hallucinogenic substances have gained popularity for therapeutic use, their dermatologic adverse effects are poorly characterized. This review characterizes the cutaneous reactions associated with psychedelic and hallucinogenic drugs. A review of PubMed and Scopus was conducted from the inception of databases to August 31, 2023. Search terms included drug names and classes (cannabis, MDMA, ecstasy, 3,4-methylenedioxymethamphetamine, psychedelics, hallucinogens, peyote, marijuana, lysergic acid diethylamide, LSD, ketamine, dimethyltryptamine, DMT, phencyclidine, PCP, dextromethorphan, psilocybin, and ayahuasca), and dermatosis terms (dermatitis, contact dermatitis, drug eruption, skin reaction, and urticaria). Studies were included if there was an association with a psychedelic or hallucinogenic and any cutaneous reaction; studies without both components were excluded. Twenty-two studies met inclusion criteria, describing reactions to cannabis (10 studies), MDMA (5 studies), ketamine (4 studies), and psilocybin (3 studies). Forty total patients were included. Among cannabis-related reactions, the most common reaction was type I hypersensitivity by topical exposure (n = 21). Three patients reported type IV hypersensitivity reactions to contact with cannabis or cannabis-derived oils, all of whom experienced vesicular contact dermatitis. Two additional patients presented with an erythema-multiforme-like reaction and acute generalized exanthematous pustulosis after systemic administration, respectively. MDMA was associated with acneiform eruptions (2 cases), an urticarial eruption, a guttate psoriasis-like reaction, a fixed drug eruption, and Stevens-Johnson syndrome (1 case). Four patients reported type I hypersensitivity reactions to ketamine. Four patients reported vesicular eruptions, cyanosis, or widespread jaundice to psilocybin. Of the cases, 8 patients had cutaneous reactions that resolved with drug cessation, 10 resolved with cessation plus treatment, and resolution in 7 cases was not reported. Zero studies were found describing other psychedelic or hallucinogenic compounds. Further research is required to characterize reactions and treatments linked to the variety of extant psychedelics and hallucinogens.

In vivo validation of psilacetin as a prodrug yielding modestly lower peripheral psilocin exposure than psilocybin

Introduction

The use of the psychedelic compound psilocybin in conjunction with psychotherapy has shown promising results in the treatment of psychiatric disorders, though the underlying mechanisms supporting these effects remain unclear. Psilocybin is a Schedule I substance that is dephosphorylated in vivo to form an active metabolite, psilocin. Psilacetin, also known as O-acetylpsilocin or 4-acetoxy-N,N-dimethyltryptamine (4-AcO-DMT), is an unscheduled compound that has long been suggested as an alternative psilocin prodrug, though direct in vivo support for this hypothesis has thus far been lacking.

Methods

This study employed liquid chromatography-tandem mass spectrometry (LC-MS/MS) to assess the time-course and plasma concentrations of psilocin following the intraperitoneal (IP) administration of psilacetin fumarate or psilocybin to male and female C57Bl6/J mice.

Results

Direct comparisons of the time courses for psilocin exposure arising from psilocybin and psilacetin found that psilocybin led to 10-25% higher psilocin concentrations than psilacetin at 15-min post-injection. The half-life of psilocin remained approximately 30 min, irrespective of whether it came from psilocybin or psilacetin. Overall, the relative amount of psilocin exposure from psilacetin fumarate was found to be approximately 70% of that from psilocybin.

Discussion

These findings provide the first direct support for the long-standing assumption in the field that psilacetin functions as a prodrug for psilocin in vivo. In addition, these results indicate that psilacetin fumarate results in lower peripheral psilocin exposure than psilocybin when dosed on an equimolar basis. Thoughtful substitution of psilocybin with psilacetin fumarate appears to be a viable approach for conducting mechanistic psychedelic research in C57Bl6/J mice.

Small-Molecule Heterocyclic Compounds: Gq-Biased Agonists for the 5-HT2A Receptor in Neuropsychiatric Treatment

Addressing the significant challenges of treating depression, anxiety, and substance abuse, this Patent Highlight explores the development of innovative small-molecule heterocyclic compounds as Gq-biased agonists of the 5-HT2A receptor. Unlike traditional treatments, these compounds selectively activate 5-HT2A-mediated Gq signaling, excluding related receptors like 5-HT2B and 5-HT2C. This selectivity suggests a more targeted and efficient therapeutic approach. The discovery of these compounds could herald a new era in neuropsychiatric treatment, promising safer, faster, and more effective interventions. Further research will illuminate their potential and applicability in clinical settings.