Psilocybin--summary of knowledge and new perspectives

Substrate recognition by the 4-hydroxytryptamine kinase PsiK in psilocybin biosynthesis

Psilocybin, the natural hallucinogen from Psilocybe (magic) mushrooms, is a highly promising drug candidate for the treatment of depression and several other mental health conditions. Biosynthesis of psilocybin from the amino acid l-tryptophan involves four strictly sequential modifications. The third of these, ATP-dependent phosphorylation of the intermediate 4-hydroxytryptamine, is catalysed by PsiK. Here we present a crystallographic analysis and a structure-based mutagenesis study of this kinase, providing insight into its mode of substrate recognition. The results of our work will support future bioengineering efforts aimed at generating variants of psilocybin with enhanced therapeutic properties.

The role of psilocybin in depressive disorders

Depression is a serious psychiatric disorder with a high incidence of morbidity and mortality and psilocybin with psychotherapy has emerged as a promising potential in the treatment of depressive disorders. A review of psilocybin use in patients with depressive disorders is presented.A search was conducted investigating the use of psilocybin in patients with depressive disorders and treatment resistant depression via PubMed/MEDLINE, EMBASE, and Google Scholar in October 2023; all publication types were permitted and limited for English-language. Keyword search terms included: "psilocybin" or "psychedelics" and "depression", or "major depressive disorder", or "treatment-resistant depression". Controlled and uncontrolled clinical trials utilizing psilocybin with psychological support for major depressive disorder and treatment-resistant depression, as well as in patients with depression and cancer related anxiety have demonstrated immediate and sustained antidepressant and anxiolytic effects. Psilocybin has a favorable safety profile and was well-tolerated in clinical trials. Psilocybin's abuse potential is low and clinical research suggests the potential of psilocybin to produce rapid and lasting antidepressant effects up to 12 months post-treatment. Psilocybin may offer a valuable contribution as an option to the currently available pharmacological and psychotherapeutic agents for patients with major depressive disorders, treatment-resistant depression as well as for patients with depression and comorbid terminal cancer. Future studies are needed to demonstrate these findings and any synergistic interaction between psilocybin and the psychological support offered to patients during sessions.

Pharmacokinetics of Psilocybin, a Tryptamine Alkaloid in Magic Mushroom (Psilocybe cubensis): A Systematic Review

Psilocybin, a major indole alkaloid found in magic mushrooms (Psilocybe cubensis), has recently drawn attention as a breakthrough therapy to treat major depressive disorder. This review aimed to summarize and identify knowledge gaps concerning their pharmacokinetic characteristics of psilocybin and its active metabolite, psilocin. Original studies related to pharmacokinetics of psilocybin conducted in vitro, animals, and humans were systematically collected from PubMed, Scopus, and ScienceDirect, from their inceptions to November 2023. Twenty articles were included in this work and assessed for study quality. A comprehensive review of the pharmacokinetics of psilocybin and psilocin in both animals and humans was performed. Psilocybin is considered a prodrug that is dephosphorylated to psilocin by alkaline phosphatase. Following ingestion, the peak psilocin plasma and brain levels were rapidly achieved in a dose-dependent manner. Psilocin is metabolized primarily through both Phase I and Phase II processes with the half-life of 2-3 hours. This review also identified lack of some pharmacokinetic related information and limitations of available research that may help direct future investigations to better understand the pharmacokinetics and improve study design including dose selection and dosage optimization.

A switch strategy for the synthesis of C4-ethylamine indole and C7-aminoindoline via controllable carbon elimination

Controllable β-carbon elimination to extrude norbornene remains a long-standing challenge in palladium and norbornene chemistry. Herein, this manuscript describes a switchable synthesis of biologically active C4-ethylaminoindole and C7-aminoindoline scaffolds by controlling β-carbon elimination, utilizing aziridine as a C-H ethylamination reagent through a C-N bond cleavage reaction. Furthermore, the protecting groups of the product can be easily removed, offering an unusual method for the synthesis of dopamine receptor agonists.

A retrospective study of the characteristics and toxicology of cases of lysergic acid diethylamide (LSD)- and psilocybin-related death in Australia

BACKGROUND AND AIMS

Lysergic acid diethylamide (LSD) and psilocybin are used as recreational drugs, and there is renewed interest in their clinical use. The current study aimed to (1) determine the circumstances of death and case characteristics of LSD- and psilocybin-related death in Australia, 2000-23; and (2) determine the toxicological profile and major autopsy findings of these cases.

METHODS

This was a retrospective exploratory study of all cases of LSD- and psilocybin-related death in Australia, 2000-23, retrieved from the National Coronial Information System.

RESULTS

A total of 43 cases were identified: 33 LSD and 10 psilocybin. The median ages were 24 years [interquartile range (IQR) = 13, range = 16-53] (LSD) and 26 years (IQR = 18.5, range = 20-58) (psilocybin), and fewer than five cases were female. The most common circumstance of death among both groups was traumatic accident (LSD 36.4%, psilocybin 40.0%). There were 12 cases of self-harm, all of which involved LSD, all by physical means. In a fifth, death was attributed to multiple drug toxicity (LSD 18.2%, psilocybin 20.0%). In one case, death was attributed solely to LSD toxicity, while in a further two cases death was attributed to a cardiovascular event following LSD consumption (one LSD only, one multiple drug toxicity). In four psilocybin cases, the cause of death was undetermined. The most common clinical presentation was severe agitation (LSD 27.3%, psilocybin 20.0%). Median blood concentrations were LSD 0.8 μg/l (IQR = 1.7, range = 0.1-3), psilocin 20 μg/l (IQR = 53.5, range = 6-83). LSD was the only drug present in 25.0% of LSD cases and psilocybin in 20.0% of psilocybin cases. Pre-existing organ pathology was uncommon.

CONCLUSIONS

Lysergic acid diethylamide (LSD)- and psilocybin-related death in Australia from 2000 to 2023 was primarily due to traumatic injury, whether through accident or self-harm. Cases of acute toxic reactions that were attributed solely to LSD were rare.

Depression clinical trials worldwide: a systematic analysis of the ICTRP and comparison with ClinicalTrials.gov

Major depressive disorder (MDD), commonly known as depression, affects over 300 million people worldwide as of 2018 and presents a wide range of clinical symptoms. The international clinical trials registry platform (ICTRP) introduced by WHO includes aggregated data from ClinicalTrials.gov and 17 other national registers, making it the largest clinical trial platform. Here we analysed data in ICTRP with the aim of providing comprehensive insights into clinical trials on depression. Applying a novel hidden duplicate identification method, 10,606 depression trials were identified in ICTRP, with ANZCTR being the largest non- ClinicalTrials.gov database at 1031 trials, followed by IRCT with 576 trials, ISRCTN with 501 trials, CHiCTR with 489 trials, and EUCTR with 351 trials. The top four most studied drugs, ketamine, sertraline, duloxetine, and fluoxetine, were consistent in both groups, but ClinicalTrials.gov had more trials for each drug compared to the non-ClinicalTrials.gov group. Out of 9229 interventional trials, 663 unique agents were identified, including approved drugs (74.5%), investigational drugs (23.2%), withdrawn drugs (1.8%), nutraceuticals (0.3%), and illicit substances (0.2%). Both ClinicalTrials.gov and non-ClinicalTrials.gov databases revealed that the largest categories were antidepressive agents (1172 in ClinicalTrials.gov and 659 in non-ClinicalTrials.gov) and nutrients, amino acids, and chemical elements (250 in ClinicalTrials.gov and 659 in non-ClinicalTrials.gov), indicating a focus on alternative treatments involving dietary supplements and nutrients. Additionally, 26 investigational antidepressive agents targeting 16 different drug targets were identified, with buprenorphine (opioid agonist), saredutant (NK2 antagonist), and seltorexant (OX2 antagonist) being the most frequently studied. This analysis addresses 40 approved drugs for depression treatment including new drug classes like GABA modulators and NMDA antagonists that are offering new prospects for treating MDD, including drug-resistant depression and postpartum depression subtypes.

[Psilocybin-Assisted Treatment of Depression, Anxiety and Substance use Disorders: Neurobiological Basis and Clinical Application]

Successful therapy of mental disorders is very important in view of the high level of suffering of those affected. Since established pharmaceutical and psychotherapeutic approaches do not lead to the desired improvement in all cases, complementary or alternative treatment methods are intensively researched. Psilocybin-assisted psychotherapy seems particularly promising, and has been approved in the USA for larger clinical trials. Psilocybin belongs to the group of psychedelics and influences psychological experiences. In assisted therapy, psilocybin is administered in controlled doses under medical supervision to patients with different mental disorders. In the studies conducted so far, longer-term positive effects could be shown after just one or a few doses. In order to provide a better understanding of the potential therapeutic mechanisms, this article will first describe neurobiological and psychological effects of psilocybin. To better assess the potential of psilocybin-assisted psychotherapy for various disorders, clinical studies conducted so far with patients administered psilocybin are reviewed.

Psilocybin induces acute anxiety and changes in amygdalar phosphopeptides independently from the 5-HT2A receptor

Psilocybin, and its metabolite psilocin, induces psychedelic effects through activation of the 5-HT2A receptor. Psilocybin has been proposed as a treatment for depression and anxiety but sometimes induces anxiety in humans. An understanding of mechanisms underlying the anxiety response will help to better develop therapeutic prospects of psychedelics. In the current study, psilocybin induced an acute increase in anxiety in behavioral paradigms in mice. Importantly, pharmacological blocking of the 5-HT2A receptor attenuates psilocybin-induced head twitch response, a behavioral proxy for the psychedelic response, but does not rescue psilocybin's effect on anxiety-related behavior. Phosphopeptide analysis in the amygdala uncovered signal transduction pathways that are dependent or independent of the 5-HT2A receptor. Furthermore, presynaptic proteins are specifically involved in psilocybin-induced acute anxiety. These insights into how psilocybin may induce short-term anxiety are important for understanding how psilocybin may best be used in the clinical framework.

Efficacy of psilocybin for treating symptoms of depression: systematic review and meta-analysis

OBJECTIVE

To determine the efficacy of psilocybin as an antidepressant compared with placebo or non-psychoactive drugs.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Five electronic databases of published literature (Cochrane Central Register of Controlled Trials, Medline, Embase, Science Citation Index and Conference Proceedings Citation Index, and PsycInfo) and four databases of unpublished and international literature (ClinicalTrials.gov, WHO International Clinical Trials Registry Platform, ProQuest Dissertations and Theses Global, and PsycEXTRA), and handsearching of reference lists, conference proceedings, and abstracts.

DATA SYNTHESIS AND STUDY QUALITY

Information on potential treatment effect moderators was extracted, including depression type (primary or secondary), previous use of psychedelics, psilocybin dosage, type of outcome measure (clinician rated or self-reported), and personal characteristics (eg, age, sex). Data were synthesised using a random effects meta-analysis model, and observed heterogeneity and the effect of covariates were investigated with subgroup analyses and metaregression. Hedges' g was used as a measure of treatment effect size, to account for small sample effects and substantial differences between the included studies' sample sizes. Study quality was appraised using Cochrane's Risk of Bias 2 tool, and the quality of the aggregated evidence was evaluated using GRADE guidelines.

ELIGIBILITY CRITERIA

Randomised trials in which psilocybin was administered as a standalone treatment for adults with clinically significant symptoms of depression and change in symptoms was measured using a validated clinician rated or self-report scale. Studies with directive psychotherapy were included if the psychotherapeutic component was present in both experimental and control conditions. Participants with depression regardless of comorbidities (eg, cancer) were eligible.

RESULTS

Meta-analysis on 436 participants (228 female participants), average age 36-60 years, from seven of the nine included studies showed a significant benefit of psilocybin (Hedges' g=1.64, 95% confidence interval (CI) 0.55 to 2.73, P<0.001) on change in depression scores compared with comparator treatment. Subgroup analyses and metaregressions indicated that having secondary depression (Hedges' g=3.25, 95% CI 0.97 to 5.53), being assessed with self-report depression scales such as the Beck depression inventory (3.25, 0.97 to 5.53), and older age and previous use of psychedelics (metaregression coefficient 0.16, 95% CI 0.08 to 0.24 and 4.2, 1.5 to 6.9, respectively) were correlated with greater improvements in symptoms. All studies had a low risk of bias, but the change from baseline metric was associated with high heterogeneity and a statistically significant risk of small study bias, resulting in a low certainty of evidence rating.

CONCLUSION

Treatment effects of psilocybin were significantly larger among patients with secondary depression, when self-report scales were used to measure symptoms of depression, and when participants had previously used psychedelics. Further research is thus required to delineate the influence of expectancy effects, moderating factors, and treatment delivery on the efficacy of psilocybin as an antidepressant.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42023388065.

Spectroscopic behavior of bufotenine and bufotenine N-oxide: Solvent and pH effects and interaction with biomembrane models

Bufotenine is a fluorescent analog of Dimethyltryptamine (DMT) that has been widely studied due to its psychedelic properties and biological activity. However, little is known about its spectroscopic properties in different media. Thus, we present in this work, for the first time, the spectroscopic behavior of bufotenine and bufotenine N-oxide by means of their fluorescence properties. Both molecules exhibit changes in optical absorption and emission spectra with variations in pH of the medium and in different solvents. Assays in the presence of biomembranes models, like micelles and liposomes, were also performed. In surfactants titration experiments, the spectral shift observed in fluorescence shows the interaction of both molecules with pre-micellar structures and with micelles. Steady state anisotropy measurements show that both bufotenine and bufotenine N-oxide, in the studied concentration range, interact with liposomes without causing changes in the fluidity of the lipid bilayer. These results can be useful in studies that aim at searching for new compounds, inspired by bufotenine and bufotenine N-oxide, with relevant pharmacological activities and also in studies that use these molecules as markers of psychiatric disorders.

Deciphering psilocybin: Cytotoxicity, anti-inflammatory effects, and mechanistic insights

A decade of clinical research has indicated psilocybin's effectiveness in treating various neuropsychiatric disorders, such as depression and substance abuse. The correlation between increased pro-inflammatory cytokines and the severity of neuropsychiatric symptoms, along with the known anti-inflammatory potential of some psychedelics, suggests an immunomodulatory role for psilocybin. This study aims to understand the mechanism of action of psilocybin by investigating the cytotoxic and immunomodulatory effects of psilocybin and psilocin on both resting and LPS-activated RAW 264.7 murine macrophages. The study evaluated the cytotoxicity of psilocybin and psilocin using an LDH assay across various doses and assessed their impact on cytokine production in RAW 264.7 cells, measuring cytokine expression via ELISA. Different doses, including those above and below the LC50, were used in both pre-treatment and post-treatment approaches. The LDH assay revealed that psilocybin is almost twice as cytotoxic as psilocin, with an LC50 of 12 ng/ml and 28 ng/ml, respectively. In resting macrophages, both psilocybin and psilocin triggered significant release of TNF- α after 4 h, with the lowest doses inducing higher levels of the cytokine than the highest doses. IL-10 expression in resting cells was only triggered by the highest dose of psilocin in the 4-hour incubation group. In LPS-stimulated cells, psilocin reduced TNF- α levels more than psilocybin in pre-treatment and post-treatment, with no significant effects on IL-10 in pre-treatment. Psilocin, but not psilocybin, induced a significant increase of IL-10 in post-treatment, leading to the conclusion that psilocin, but not psilocybin, exerts anti-inflammatory effects on classically activated macrophages.

Methyl transfer in psilocybin biosynthesis

Psilocybin, the natural hallucinogen produced by Psilocybe ("magic") mushrooms, holds great promise for the treatment of depression and several other mental health conditions. The final step in the psilocybin biosynthetic pathway, dimethylation of the tryptophan-derived intermediate norbaeocystin, is catalysed by PsiM. Here we present atomic resolution (0.9 Å) crystal structures of PsiM trapped at various stages of its reaction cycle, providing detailed insight into the SAM-dependent methylation mechanism. Structural and phylogenetic analyses suggest that PsiM derives from epitranscriptomic N6-methyladenosine writers of the METTL16 family, which is further supported by the observation that bound substrates physicochemically mimic RNA. Inherent limitations of the ancestral monomethyltransferase scaffold hamper the efficiency of psilocybin assembly and leave PsiM incapable of catalysing trimethylation to aeruginascin. The results of our study will support bioengineering efforts aiming to create novel variants of psilocybin with improved therapeutic properties.

Psilocybin, an Effective Treatment for Major Depressive Disorder in Adults - A Systematic Review

Psilocybin is a classical psychedelic which has been utilised for healing purposes for millenia. However, with its classification as a Schedule I substance, research into this compound is scarce with few FDA-approved clinical studies. Despite this, profound findings into its antidepressant effects (largely through its action on 5-HT1a receptors) in mental illnesses such as major depressive disorder have rapidly increased interest back into their potential therapeutic benefits. This systematic review provides an analysis of the studies examining the clinical use of psilocybin for major depressive disorder. In total 6 studies were selected, including 319 participants, with half being randomised controlled trials and half open label trials. In every study psychological support was included as an integral part of the treatment. It was found that every study significantly favoured the use of psilocybin in reducing depressive symptoms, with few side effects. This gives psilocybin an advantage over commonly prescribed selective serotonin reuptake inhibitors (SSRIs), which carry more risk and cause more adverse effects. This drug therefore shows promise for being used as a clinical treatment for major depressive disorder, however future research should develop a paradigm for its use, with the timing of sessions and type of psychological support specified to allow for more precise analysis of the clinical effects of the drug. Additionally, more studies into its clinical efficacy are needed for appropriate detection of any publication bias. With this, psilocybin could prove to be revolutionary in treating depression and become an alternative medication to SSRIs.

The effect of casing and gypsum on the yield and psychoactive tryptamine content of Psilocybe cubensis (Earle) Singer

Psychedelic fungi have experienced a surge in interest in recent years. Most notably, the fungal secondary metabolite psilocybin has shown tremendous promise in the treatment of various psychiatric disorders. The mushroom species that produce this molecule are poorly understood. Here we sought to examine for the first time, the response of a psilocybin-producing species Psilocybe cubensis to casing (peat moss and vermiculite) and supplementation with gypsum (calcium sulfate dihydrate), two common practices in commercial mushroom cultivation. Mycelial samples of genetically authenticated P. cubensis were used to inoculate popcorn grain bags. The fully colonized bags of popcorn grain (0.15 kg) were transferred to bins of 0.85 kg pasteurized horse manure, with or without 1 cm thick layer of casing and/or 5 % gypsum. Our results indicate that the use of a casing layer significantly increases the biological efficiency (161.5 %), by approximately four fold, in comparison to control (40.5 %), albeit with a slight delay (∼2 days) for obtaining fruiting bodies and a somewhat reduced total tryptamine content (0.85 %) as gauged by High Performance Liquid Chromatography measurements. Supplementation with both casing and gypsum, however, appears to promote maximal yields (896.6 g/kg of dried substrate), with a biological efficiency of 89.6 %, while also maintaining high total tryptamine expressions (0.95 %). These findings, revealing methods for maximizing yield of harvest and expressions of psychoactive tryptamines, may prove useful for both home growers and commercial cultivators of this species, and ultimately support the growth of a robust industry with high quality natural products.

Psilocybin-assisted therapy for severe alcohol use disorder: protocol for a double-blind, randomized, placebo-controlled, 7-month parallel-group phase II superiority trial

BACKGROUND

A significant number of individuals with alcohol use disorder remain unresponsive to currently available treatments, which calls for the development of new alternatives. In parallel, psilocybin-assisted therapy for alcohol use disorder has recently yielded promising preliminary results. Building on extant findings, the proposed study is set to evaluate the feasibility and preliminary clinical efficacy of psilocybin-assisted therapy when incorporated as an auxiliary intervention during inpatient rehabilitation for severe alcohol use disorder. Moreover, it intends to pinpoint the modifications in the two core neurocognitive systems underscored by dual-process models of addiction.

METHODS

In this double-blind, randomized, placebo-controlled, 7-month parallel-group phase II superiority trial, 62 participants aged 21-64 years will be enrolled to undergo psilocybin-assisted therapy as part of a 4-week inpatient rehabilitation for severe alcohol use disorder. The experimental group will receive a high dose of psilocybin (30 mg), whereas the control group will receive an active placebo dose of psilocybin (5 mg), both within the context of a brief standardized psychotherapeutic intervention drawing from key elements of acceptance and commitment therapy. The primary clinical outcome is the between-group difference regarding the change in percentage of heavy drinking days from baseline to four weeks posthospital discharge, while safety and feasibility metrics will also be reported as primary outcomes. Key secondary assessments include between-group differences in terms of changes in (1) drinking behavior parameters up to six months posthospital discharge, (2) symptoms of depression, anxiety, trauma, and global functioning, (3) neuroplasticity and key neurocognitive mechanisms associated with addiction, and (4) psychological processes and alcohol-related parameters.

DISCUSSION

The discussion outlines issues that might arise from our design.

TRIAL REGISTRATION

EudraCT 2022-002369-14 and NCT06160232.

Safety, feasibility, tolerability, and clinical effects of repeated psilocybin dosing combined with non-directive support in the treatment of obsessive-compulsive disorder: protocol for a randomized, waitlist-controlled trial with blinded ratings

Background

To date, few randomized controlled trials of psilocybin with non-directive support exist for obsessive-compulsive disorder (OCD). Results and participant feedback from an interim analysis of an ongoing single-dose trial (NCT03356483) converged on the possibility of administering a higher fixed dose and/or more doses of psilocybin in future trials for presumably greater benefits.

Objectives

This trial aims to evaluate the safety, feasibility, tolerability, and clinical effects of two doses of psilocybin paired with non-directive support in the treatment of OCD. This trial also seeks to examine whether two doses of psilocybin lead to greater OCD symptom reduction than a single dose, and to elucidate psychological mechanisms underlying the effects of psilocybin on OCD.

Design

A randomized (1:1), waitlist-controlled design with blinded ratings will be used to examine the effects of two doses of oral psilocybin paired with non-directive support vs. waitlist control on OCD symptoms. An adaptive dose selection strategy will be implemented (i.e., first dose: 25 mg; second dose: 25 or 30 mg).

Methods and analysis

This single-site trial will enroll 30 adult participants with treatment-refractory OCD. Aside from safety, feasibility, and tolerability metrics, primary outcomes include OCD symptoms assessed on the Yale-Brown Obsessive-Compulsive Scale - Second Edition (Y-BOCS-II). A blinded independent rater will assess primary outcomes at baseline and the primary endpoint at the end of the second dosing week. Participants will be followed up to 12 months post-second dosing. Participants randomized to waitlist will be rescreened after 7 weeks post-randomization, and begin their delayed treatment phase thereafter if still eligible.

Ethics

Written informed consent will be obtained from participants. The institutional review board has approved this trial (protocol v. 1.7; HIC #2000032623).

Discussion

This study seeks to advance our ability to treat refractory OCD, and catalyze future research seeking to optimize the process of psilocybin treatment for OCD through understanding relevant psychological mechanisms.Clinical trial registration: ClinicalTrials.gov, identifier NCT05370911.

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.

Efficacy, Safety, and Tolerability of Psychedelics in Treatment-Resistant Depression (TRD)

Major depressive disorder (MDD) is a highly prevalent psychiatric disorder, associated with substantial burden and large economical costs. Notwithstanding various conventional antidepressant treatment options, a large portion of depressed people (ca. 30%) fails to respond to first-line treatment, resulting in treatment-resistant depression (TRD). Although non-response to multiple antidepressant interventions is a common outcome, a consensus definition of TRD is not yet available. In practice, TRD is applied when two or more successive treatments with different antidepressants are not working. The last decade's intense research into new medicines for TRD has led to two developments, using typical or serotonergic (psilocybin, ayahuasca) and atypical (glutamatergic) psychedelics (ketamine, esketamine). Both approaches, although via different entrance mechanism, exhibit a fast onset but also long-lasting antidepressant effect far beyond the biological presence of the drug in the body, strongly indicating that downstream mechanisms activated by signaling cascades in the brain are involved. The present chapter describes the clinical development of psilocybin and esketamine for TRD and discusses the problems involved in the use of a proper placebo because of the psychotomimetic (psilocybin) or dissociative (ketamine) effects that interfere with performing "blind" studies. Nevertheless, intranasal esketamine was developed and approved for TRD, whereas psilocybin has shown positive results. Adverse effects and tolerability of both drugs in the dose ranges used are generally acceptable. The emergence of anti-TRD medicines for treatment of a very severe disease is a breakthrough in psychiatry.

Molecular and Medical Aspects of Psychedelics

Psychedelics belong to the oldest psychoactive drugs. They arouse recent interest due to their therapeutic applications in the treatment of major depressive disorder, substance use disorder, end-of-life anxiety,= and anxiety symptoms, and obsessive-compulsive disorder. In this review, the current state of preclinical research on the mechanism of action, neurotoxicity, and behavioral impact of psychedelics is summarized. The effect of selective 5-HT2A receptor agonists, 25I- and 25B-NBOMe, after acute and repeated administration is characterized and compared with the effects of a less selective drug, psilocybin. The data show a significant effect of NBOMes on glutamatergic, dopaminergic, serotonergic, and cholinergic neurotransmission in the frontal cortex, striatum, and nucleus accumbens. The increases in extracellular levels of neurotransmitters were not dose-dependent, which most likely resulted from the stimulation of the 5-HT2A receptor and subsequent activation of the 5-HT2C receptors. This effect was also observed in the wet dog shake test and locomotor activity. Chronic administration of NBOMes elicited rapid development of tolerance, genotoxicity, and activation of microglia. Acute treatment with psilocybin affected monoaminergic and aminoacidic neurotransmitters in the frontal cortex, nucleus accumbens, and hippocampus but not in the amygdala. Psilocybin exhibited anxiolytic properties resulting from intensification of GABAergic neurotransmission. The data indicate that NBOMes as selective 5-HT2A agonists exert a significant effect on neurotransmission and behavior of rats while also inducing oxidative DNA damage. In contrast to NBOMes, the effects induced by psilocybin suggest a broader therapeutic index of this drug.

Unveiling the Psychedelic Journey: An Appraisal of Psilocybin as a Profound Antidepressant Therapy

Depression, a global health concern with significant implications for suicide rates, remains challenging to treat effectively with conventional pharmacological options. The existing pharmaceutical interventions for these illnesses need daily dosing, are accompanied by various adverse effects, and may exhibit limited efficacy in certain cases. However, hope emerges from an unlikely source-Psilocybin, a natural hallucinogen found in certain mushrooms. Recently, this enigmatic compound has garnered attention for its potential therapeutic benefits in addressing various mental health issues, including depression. Psilocybin alters mood, cognition, and perception by acting on a particular subtype of serotonin receptors in the brain. It's feasible that these shifts in consciousness will promote healing development, offering a novel approach to depression management. This comprehensive review explores psilocybin, derived from specific mushrooms, and its implications in the treatment of depression. The study examines new perspectives and therapeutic possibilities surrounding psilocybin, addressing existing gaps in academic literature. It delves into its biosynthesis, unique mechanisms of action, therapeutic applications, and anti-depressive effects. By uncovering the potential of this mind-altering substance, the review aims to advance psychiatric care, offering hope to those globally affected by depression.

Psilocybin and Eugenol Reduce Inflammation in Human 3D EpiIntestinal Tissue

Inflammation plays a pivotal role in the development and progression of inflammatory bowel disease (IBD), by contributing to tissue damage and exacerbating the immune response. The investigation of serotonin receptor 2A (5-HT2A) ligands and transient receptor potential (TRP) channel ligands is of significant interest due to their potential to modulate key inflammatory pathways, mitigate the pathological effects of inflammation, and offer new avenues for therapeutic interventions in IBD. This study investigates the anti-inflammatory effects of 5-HT2A ligands, including psilocybin, 4-AcO-DMT, and ketanserin, in combination with TRP channel ligands, including capsaicin, curcumin, and eugenol, on the inflammatory response induced by tumor necrosis factor (TNF)-α and interferon (IFN)-γ in human 3D EpiIntestinal tissue. Enzyme-linked immunosorbent assay was used to assess the expression of pro-inflammatory markers TNF-α, IFN-γ, IL-6, IL-8, MCP-1, and GM-CSF. Our results show that psilocybin, 4-AcO-DMT, and eugenol significantly reduce TNF-α and IFN-γ levels, while capsaicin and curcumin decrease these markers to a lesser extent. Psilocybin effectively lowers IL-6 and IL-8 levels, but curcumin, capsaicin, and 4-AcO-DMT have limited effects on these markers. In addition, psilocybin can significantly decrease MCP-1 and GM-CSF levels. While ketanserin lowers IL-6 and GM-CSF levels, there are no effects seen on TNF-α, IFN-γ, IL-8, or MCP-1. Although synergistic effects between 5-HT2A and TRP channel ligands are minimal in this study, the results provide further evidence of the anti-inflammatory effects of psilocybin and eugenol. Further research is needed to understand the mechanisms of action and the feasibility of using these compounds as anti-inflammatory therapies for conditions like IBD.

A "Magic Mushroom" Multi-Product Sesquiterpene Synthase

Psilocybe "magic mushrooms" are chemically well understood for their psychotropic tryptamines. However, the diversity of their other specialized metabolites, in particular terpenoids, has largely remained an open question. Yet, knowledge on the natural product background is critical to understand if other compounds modulate the psychotropic pharmacological effects. CubA, the single clade II sesquiterpene synthase of P. cubensis, was heterologously produced in Escherichia coli and characterized in vitro, complemented by in vivo product formation assays in Aspergillus niger as a heterologous host. Extensive GC-MS analyses proved a function as multi-product synthase and, depending on the reaction conditions, cubebol, β-copaene, δ-cadinene, and germacrene D were detected as the major products of CubA. In addition, mature P. cubensis carpophores were analysed chromatographically which led to the detection of β-copaene and δ-cadinene. Enzymes closely related to CubA are encoded in the genomes of various Psilocybe species. Therefore, our results provide insight into the metabolic capacity of the entire genus.

Back from the rabbit hole. Theoretical considerations and practical guidelines on psychedelic integration for mental health specialists

The growing interest in and prevalence of the use of psychedelics, as well as the potential benefits and negative consequences associated with psychedelic experiences, create a need for mental health specialists to be able to provide adequate and effective intervention regarding the content and consequences of these experiences, that is, psychedelic integration. At the same time, current graduate training in psychiatry, psychology, psychotherapy, counseling, etc., fails to adequately prepare professionals for such interventions. In order to fill this gap, an international, bottom-up project was established to attempt developing guidelines. This project was conducted by means of literature reviews as well as roundtable discussions among project participants, leading to a consensus on the guidelines' final scope and content. Drawing from the outcomes of this project, this article presents proposed comprehensive guidelines covering both theoretical and practical aspects of psychedelic integration, that are intended to serve as a resource for various mental health specialists who may encounter individuals in need of support considering their psychedelic experiences. These guidelines encompass clinician-friendly information on the effects of psychedelics, a definition of psychedelic integration, the general theoretical considerations linked to utilization of psychedelic experiences in clinical practice, a simple model organizing the course of psychedelic integration practice, as well as an overview of the current models of psychedelic integration, along with a selective presentation of basic and specific interventions derived from various psychotherapeutic approaches that can be employed in the practice of psychedelic integration.

The zebrafish for preclinical psilocybin research

In this review, we discuss the possible utility of zebrafish in research on psilocybin, a psychedelic drug whose recreational use as well as possible clinical application are gaining increasing interest. First, we review behavioral tests with zebrafish, focussing on anxiety and social behavior, which have particular relevance in the context of psilocybin research. Next, we briefly consider methods of genetic manipulations with which psilocybin's phenotypical effects and underlying mechanisms may be investigated in zebrafish. We briefly review the known mechanisms of psilocybin, and also discuss what we know about its safety and toxicity profile. Last, we discuss examples of how psilocybin may be employed for testing treatment efficacy in preclinical research for affective disorders in zebrafish. We conclude that zebrafish has a promising future in preclinical research on psychedelic drugs.

Improvement in OCD symptoms associated with serotoninergic psychedelics: a retrospective online survey

A renewed interest in the use of psychedelics for treating obsessive compulsive disorder (OCD) has emerged in the last 20 years. But pre-clinical and clinical evidence remain scarce, and little is known about the factor determining the magnitude and persistence of the therapeutic effect. We therefore designed a retrospective online survey to explore, in the general population using psychoactive drugs, their impact on OCD symptoms. We also assessed the attitude of the participants towards the substance in term of frequency of intakes. In a sample of 174 participants, classic psychedelics were reported as the only substances effective at reducing OCD symptoms. In classic psychedelics users, symptoms reduction was associated with the intensity of acute effects, itself correlated to the dose. Reports on the persistence of the therapeutic effect varied from weeks to months, but we could not find any predicting factor. Finally, the occurrence and frequency of subsequent intakes, which seemed to be limited in our sample, were predicted by the magnitude and persistence of the therapeutic effect, respectively. Our observations support the hypothesis of classic psychedelics efficacy in reducing OCD symptoms but a careful evaluation of the persistence of this effect is still needed.

Psilocybin in neuropsychiatry: a review of its pharmacology, safety, and efficacy

Psilocybin is a tryptamine alkaloid found in some mushrooms, especially those of the genus Psilocybe. Psilocybin has four metabolites including the pharmacologically active primary metabolite psilocin, which readily enters the systemic circulation. The psychoactive effects of psilocin are believed to arise due to the partial agonist effects at the 5HT2A receptor. Psilocin also binds to various other receptor subtypes although the actions of psilocin at other receptors are not fully explored. Psilocybin administered at doses sufficient to cause hallucinogenic experiences has been trialed for addictive disorders, anxiety and depression. This review investigates studies of psilocybin and psilocin and assesses the potential for use of psilocybin and a treatment agent in neuropsychiatry. The potential for harm is also assessed, which may limit the use of psilocybin as a pharmacotherapy. Careful evaluation of the number needed to harm vs the number needed to treat will ultimately justify the potential clinical use of psilocybin. This field needs a responsible pathway forward.

Underlying pharmacological mechanisms of psilocin-induced broadband desynchronization and disconnection of EEG in rats

Introduction

Psilocybin is one of the most extensively studied psychedelic drugs with a broad therapeutic potential. Despite the fact that its psychoactivity is mainly attributed to the agonism at 5-HT2A receptors, it has high binding affinity also to 5-HT2C and 5-HT1A receptors and indirectly modulates the dopaminergic system. Psilocybin and its active metabolite psilocin, as well as other serotonergic psychedelics, induce broadband desynchronization and disconnection in EEG in humans as well as in animals. The contribution of serotonergic and dopaminergic mechanisms underlying these changes is not clear. The present study thus aims to elucidate the pharmacological mechanisms underlying psilocin-induced broadband desynchronization and disconnection in an animal model.

Methods

Selective antagonists of serotonin receptors (5-HT1A WAY100635, 5-HT2A MDL100907, 5-HT2C SB242084) and antipsychotics haloperidol, a D2 antagonist, and clozapine, a mixed D2 and 5-HT receptor antagonist, were used in order to clarify the underlying pharmacology.

Results

Psilocin-induced broadband decrease in the mean absolute EEG power was normalized by all antagonists and antipsychotics used within the frequency range 1-25 Hz; however, decreases in 25-40 Hz were influenced only by clozapine. Psilocin-induced decrease in global functional connectivity and, specifically, fronto-temporal disconnection were reversed by the 5-HT2A antagonist while other drugs had no effect.

Discussion

These findings suggest the involvement of all three serotonergic receptors studied as well as the role of dopaminergic mechanisms in power spectra/current density with only the 5-HT2A receptor being effective in both studied metrics. This opens an important discussion on the role of other than 5-HT2A-dependent mechanisms underlying the neurobiology of psychedelics.

Global species diversity and distribution of the psychedelic fungal genus Panaeolus

Psychedelic fungi have received considerable attention recently due to their promising treatment potential of several psychiatric disorders and medical conditions, both in clinical settings but also as a nutraceutical. Besides research, a growing number of companies are developing capacity to conduct research and clinical trials where these fungi and their products can be used, and to provide these fungi to the public market that are rapidly becoming legal across the world. Whereas Psilocybe species are better known as psychedelic fungi, species in Panaeolus are also reputed to contain the psychedelic compound psilocybin and used recreationally. For the novice, there is no contemporary scientific summary of all the species in this genus that are known to be psychedelic, compared to those that are not. The global distribution and species diversity of these brown to white, often inconspicuous mushrooms are also not summarised, nor is it known to what extent DNA sequence data that are needed for identification have been generated for all of the species in this genus. However, psychedelic Panaeolus species are used and moved across the world. This lack of data makes it difficult to regulate bioexploitation and apply law enforcement of these fungi and the compounds they contain, especially seen in the light of the rapid development of the related markets. The aim of this review is to summarise current scientific data and knowledge on the species biodiversity, geographical distribution, extent of sequence data for identification purposes, and the psychedelic potential of species, based on published results. The review revealed where species are mostly known from, while also indicating areas seriously lacking such biodiversity data. A significant degree of study across the world is still needed to confirm which of these species are truly psychedelic and exactly what compounds they can produce.

In silico characterization of the psilocybin biosynthesis pathway

Nearly all mushrooms of the Psilocybe genus contain the natural product psilocybin, which is a psychoactive alkaloid derived from l-tryptophan. Considering their use in ancient times, as well as their psychedelic properties, these mushrooms have re-emerged with psychotherapeutic potential for treating depression, which has triggered increased pharmaceutical interest. However, the psilocybin biosynthesis pathway was only recently defined and, as such, little exists in the way of structural data. Accordingly, the aim of this study was to structurally characterize this pathway by generating homology models for the four Psilocybe cubensis enzymes involved in psilocybin biosynthesis (PsiD, a decarboxylase; PsiH, a monooxygenase; PsiK, a phosphotransferase; PsiM, a methyltransferase). Following initial model generation and alignment with the identified structural templates, repeated refinement of the models was carried out using secondary structure prediction, geometry evaluation, energy minimization, and molecular dynamics simulations in water. The final models were then evaluated using molecular docking interactions with their substrates, i.e., psilocybin precursors (l-tryptophan, tryptamine, 4-hydroxytryptamine, and norbaeocystin/baeocystin), all of which generated feasible binding modes for the expected biotransformation. Further plausibility of the psilocybin → aeruginascin, 4-hydroxytryptamine → norpsilocin, and tryptamine → N,N-dimethyltryptamine conversions, all mediated by the generated model for PsiM, suggests valid routes of formation for these key secondary metabolites. The structural characterization of these enzymes and their binding modes which emerged from this study can lead to a better understanding of psilocybin synthesis, thereby paving the way for the development of novel substrates and selective inhibitors, as well as improved biotechnological manipulation and production of psilocybin in vitro.

The evolution and ecology of psilocybin in nature

Fungi produce diverse metabolites that can have antimicrobial, antifungal, antifeedant, or psychoactive properties. Among these metabolites are the tryptamine-derived compounds psilocybin, its precursors, and natural derivatives (collectively referred to as psiloids), which have played significant roles in human society and culture. The high allocation of nitrogen to psiloids in mushrooms, along with evidence of convergent evolution and horizontal transfer of psilocybin genes, suggest they provide a selective benefit to some fungi. However, no precise ecological roles of psilocybin have been experimentally determined. The structural and functional similarities of psiloids to serotonin, an essential neurotransmitter in animals, suggest that they may enhance the fitness of fungi through interference with serotonergic processes. However, other ecological mechanisms of psiloids have been proposed. Here, we review the literature pertinent to psilocybin ecology and propose potential adaptive advantages psiloids may confer to fungi.

Cardiac Arrest Associated With Psilocybin Use and Hereditary Hemochromatosis

Recreational drug use is a significant public health concern in various countries. It is well understood that usage of psychedelics/hallucinogens, such as lysergic acid diethylamide (LSD), ecstasy, phencyclidine (PCP), and psilocybin-containing mushrooms, has increased significantly over the last few decades, particularly in adolescents and young adults, yet the effects of these recreational drugs are poorly understood. Psilocybin has recently been studied as an alternative to traditional antidepressant therapies with potentially benign side effects. Here, we present the case of a 48-year-old male with a past medical history of attention-deficit/hyperactivity disorder on lisdexamfetamine who presented after a syncopal episode witnessed by his wife at home. He was found to be in ventricular fibrillation and subsequently had an extensive workup with cardiac magnetic resonance imaging (MRI), ischemic evaluation, and electrophysiology, which were unrevealing. He then received an automatic implantable cardiac defibrillator and was incidentally found to have hereditary hemochromatosis on outpatient follow-up. His polypharmacy may have potentially led to catecholamine release, leading to ventricular arrhythmia.

Safety, tolerability, and clinical and neural effects of single-dose psilocybin in obsessive-compulsive disorder: protocol for a randomized, double-blind, placebo-controlled, non-crossover trial

Background

Psilocybin may help treat obsessive-compulsive disorder (OCD). To date, only one open-label study of psilocybin for OCD exists, necessitating further investigation with a randomized controlled design. The neural correlates of psilocybin's effects on OCD have also not been studied.

Objectives

This first-of-its-kind trial aims to evaluate the feasibility, safety, and tolerability of psilocybin in the treatment of OCD, provide preliminary evidence on the effects of psilocybin on OCD symptoms, and elucidate neural mechanisms that may mediate psilocybin's effects on OCD.

Design

We use a randomized (1:1), double-blind, placebo-controlled, non-crossover design to examine the clinical and neural effects of either a single dose of oral psilocybin (0.25 mg/kg) or active placebo-control agent (250 mg of niacin) on OCD symptoms.

Methods and analysis

We are enrolling 30 adult participants at a single site in Connecticut, USA who have failed at least one trial of standard care treatment (medication/psychotherapy) for OCD. All participants will also receive unstructured, non-directive psychological support during visits. Aside from safety, primary outcomes include OCD symptoms over the past 24 h, assessed by the Acute Yale-Brown Obsessive-Compulsive Scale and Visual Analog Scale ratings. These are collected by blinded, independent raters at baseline and the primary endpoint of 48 h post-dosing. Total follow-up is 12 weeks post-dosing. Resting state neuroimaging data will be collected at baseline and primary endpoint. Participants randomized to placebo will be offered the chance to return for an open-label dose of 0.25 mg/kg.

Ethics statement

All participants will be required to provide written informed consent. The trial (protocol v. 5.2) was approved by the institutional review board (HIC #2000020355) and registered with ClinicalTrials.gov (NCT03356483).

Discussion

This study may represent an advance in our ability to treat refractory OCD, and pave the way for future studies of neurobiological mechanisms of OCD that may respond to psilocybin.

Engineering Saccharomyces cerevisiae for the de novo Production of Halogenated Tryptophan and Tryptamine Derivatives

The indole scaffold is a recurring structure in multiple bioactive heterocycles and natural products. Substituted indoles like the amino acid tryptophan serve as a precursor for a wide range of natural products with pharmaceutical or agrochemical applications. Inspired by the versatility of these compounds, medicinal chemists have for decades exploited indole as a core structure in the drug discovery process. With the aim of tuning the properties of lead drug candidates, regioselective halogenation of the indole scaffold is a common strategy. However, chemical halogenation is generally expensive, has a poor atom economy, lacks regioselectivity, and generates hazardous waste streams. As an alternative, in this work we engineer the industrial workhorse Saccharomyces cerevisiae for the de novo production of halogenated tryptophan and tryptamine derivatives. Functional expression of bacterial tryptophan halogenases together with a partner flavin reductase and a tryptophan decarboxylase resulted in the production of halogenated tryptophan and tryptamine with chlorine or bromine. Furthermore, by combining tryptophan halogenases, production of di-halogenated molecules was also achieved. Overall, this works paves the road for the production of new-to-nature halogenated natural products in yeast.

LSD, madness and healing: Mystical experiences as possible link between psychosis model and therapy model

BACKGROUND

For a century, psychedelics have been investigated as models of psychosis for demonstrating phenomenological similarities with psychotic experiences and as therapeutic models for treating depression, anxiety, and substance use disorders. This study sought to explore this paradoxical relationship connecting key parameters of the psychotic experience, psychotherapy, and psychedelic experience.

METHODS

In a randomized, double-blind, placebo-controlled, crossover design, 24 healthy volunteers received 50 μg d-lysergic acid diethylamide (LSD) or inactive placebo. Psychotic experience was assessed by aberrant salience (Aberrant Salience Inventory, ASI), therapeutic potential by suggestibility (Creative Imagination Scale, CIS) and mindfulness (Five Facet Mindfulness Questionnaire, FFMQ; Mindful Attention Awareness Scale, MAAS; Experiences Questionnaire, EQ), and psychedelic experience by four questionnaires (Altered State of Consciousness Questionnaire, ASC; Mystical Experiences Questionnaire, MEQ; Challenging Experiences Questionnaire, CEQ; Ego-Dissolution Inventory, EDI). Relationships between LSD-induced effects were examined.

RESULTS

LSD induced psychedelic experiences, including alteration of consciousness, mystical experiences, ego-dissolution, and mildly challenging experiences, increased aberrant salience and suggestibility, but not mindfulness. LSD-induced aberrant salience correlated highly with complex imagery, mystical experiences, and ego-dissolution. LSD-induced suggestibility correlated with no other effects. Individual mindfulness changes correlated with aspects of aberrant salience and psychedelic experience.

CONCLUSIONS

The LSD state resembles a psychotic experience and offers a tool for healing. The link between psychosis model and therapeutic model seems to lie in mystical experiences. The results point to the importance of meaning attribution for the LSD psychosis model and indicate that psychedelic-assisted therapy might benefit from therapeutic suggestions fostering mystical experiences.

Effect of psilocybin on decision-making and motivation in the healthy rat

Psilocybin and its active metabolite psilocin are hallucinogenic serotonergic agonists with high affinity for several serotonin receptors. In addition to underlying the hallucinogenic effects of these compounds, serotonin receptor activation also has important effects on decision-making and goal-directed behaviors. The impact of psilocybin and psilocin on these cognitive systems, however, remains unclear. This study investigated the effects of psilocybin treatment on decision-making and motivation in healthy male and female rats. We compared probability and delay discounting performance of psilocybin treated (1 mg/kg) to vehicle rats (n = 10/sex/group), and further assessed motivation in each group using a progressive ratio task. We also confirmed drug action by assessing head twitch responses after psilocybin treatment (1 mg/kg). Results from this study demonstrated that exposure to 1 mg/kg psilocybin did not affect decision-making in the probability and delay discounting tasks and did not reduce response rates in the progressive ratio task. However, psilocybin treatment did cause the expected increase in head twitch responses in both male and female rats, demonstrating that the drug was delivered at a pharmacologically relevant dosage. Combined, these results suggest that psilocybin may not impair or improve decision-making and motivation. Considering recent interest in psilocybin as a potential fast-acting therapeutic for a variety of mental health disorders, our findings also suggest the therapeutic effects of this drug may not be mediated by changes to the brain systems underlying reward and decision-making. Finally, these results may have important implications regarding the relative safety of this compound, suggesting that widespread cognitive impairments may not be seen in subjects, even after chronic treatment.

Considerations in assessing the abuse potential of psychedelics during drug development

The recent increase in clinical research on the potential therapeutic uses of classic psychedelics has prompted the need to revisit the assessment of the abuse potential of these drugs. The term "classic psychedelic" is used in this manuscript to describe serotonergic 5-HT_2A agonists that alter perception, cognition, and mood (i.e., psychedelic effects) and that are currently controlled in Schedule I of the Controlled Substances Act (CSA). Schedule I drugs are subject to the most restrictive controls under the CSA, as they are considered to have a high abuse potential and no currently accepted medical use in the United States (USA). However, these classic psychedelics were placed in Schedule I at the time the CSA was enacted in 1970, and their abuse potential has not been systematically assessed using modern methodology. This paper provides an overview of scientific evaluation of the abuse potential of classic psychedelics and delineates the data that will be needed in support of a recommendation for the rescheduling, if a drug product containing a classic psychedelic gains FDA approval. This article is part of the Special Issue on 'National Institutes of Health Psilocybin Research Speaker Series'.

Experiences of psilocybin treatment for clinical conditions: A qualitative meta-synthesis

There is increasing clinical interest in the use of psilocybin. There is emerging evidence of the efficacy of psilocybin for the treatment of a range of clinical conditions. Mental health nurses have a unique set of skills for caring for people who are hallucinating. To expand these skills to meet the developing clinical interest in the therapeutic use of psilocybin, it is helpful to understand the experience from the perspective of the person being treated with psilocybin. A qualitative meta-synthesis was conducted to examine how those with psilocybin described their experiences to identify whether its effects are similar across different health conditions. Ten studies were included in the review. The health conditions studied were cancer, depression, HIV, substance use disorder, smoking cessation and trauma. The synthesis of findings identified three themes that were common across the studies despite the health condition: acceptance, connection and transformation. The review provides helpful insights into how people experience psilocybin and its effects on their health condition.

Transcriptomic Analysis of Glycosylation and Neuroregulatory Pathways in Rodent Models in Response to Psychedelic Molecules

The potential for psychedelic molecules in impacting cognitive flexibility has long been supported and acknowledged across scientific reports. In the current study, an approach leveraging knowledge-based gene-set information analysis has been adopted to explore the potential impact of psychedelic molecules on both glycosylation, (a post-translational modifications (PTM)) and on neuro-regulatory pathways. Though limitations and restrictions rise from the scarcity of publicly available 'omics' data, targeted analysis enabled us to identify a number of key glycogenes (Hexb, Hs6st2, Col9a2, B3gat2, Mgat5, Bgn) involved the structural organization of extracellular matrix and neuroprotective factors (Kl, Pomc, Oxt, Gal, Avp, Cartpt) which play vital roles in neuron protection, development as well as synaptic stability. In response to psychedelic molecules, we found that these genes and associated pathways are transcriptional altered in rodent models. The approach used indicates the potential to exploit existing datasets for hypothesis generation and testing for the molecular processes which play a role in the physiological response to psychedelic molecule effects. These reported findings, which focused on alterations in glycogenes and neuro-regulatory factors may provide a novel range of biomarkers to track the beneficial, as well as potential toxicological effects of psychedelic molecules.

DNA Authentication and Chemical Analysis of Psilocybe Mushrooms Reveal Widespread Misdeterminations in Fungaria and Inconsistencies in Metabolites

The mushroom genus Psilocybe is best known as the core group of psychoactive mushrooms, yet basic information on their diversity, taxonomy, chemistry, and general biology is still largely lacking. In this study, we reexamined 94 Psilocybe fungarium specimens, representing 18 species, by DNA barcoding, evaluated the stability of psilocybin, psilocin, and their related tryptamine alkaloids in 25 specimens across the most commonly vouchered species (Psilocybe cubensis, Psilocybe cyanescens, and Psilocybe semilanceata), and explored the metabolome of cultivated P. cubensis. Our data show that, apart from a few well-known species, the taxonomic accuracy of specimen determinations is largely unreliable, even at the genus level. A substantial quantity of poor-quality and mislabeled sequence data in public repositories, as well as a paucity of sequences derived from types, further exacerbates the problem. Our data also support taxon- and time-dependent decay of psilocybin and psilocin, with some specimens having no detectable quantities of them. We also show that the P. cubensis metabolome possibly contains thousands of uncharacterized compounds, at least some of which may be bioactive. Taken together, our study undermines commonly held assumptions about the accuracy of names and presence of controlled substances in fungarium specimens identified as Psilocybe spp. and reveals that our understanding of the chemical diversity of these mushrooms is largely incomplete. These results have broader implications for regulatory policies pertaining to the storage and sharing of fungarium specimens as well as the use of psychoactive mushrooms for recreation and therapy. IMPORTANCE The therapeutic use of psilocybin, the active ingredient in "magic mushrooms," is revolutionizing mental health care for a number of conditions, including depression, posttraumatic stress disorder (PTSD), and end-of-life care. This has spotlighted the current state of knowledge of psilocybin, including the organisms that endogenously produce it. However, because of international regulation of psilocybin as a controlled substance (often included on the same list as cocaine and heroin), basic research has lagged far behind. Our study highlights how the poor state of knowledge of even the most fundamental scientific information can impact the use of psilocybin-containing mushrooms for recreational or therapeutic applications and undermines critical assumptions that underpin their regulation by legal authorities. Our study shows that currently available chemical studies are mainly inaccurate, irreproducible, and inconsistent, that there exists a high rate of misidentification in museum collections and public databases rendering even names unreliable, and that the concentration of psilocybin and its tryptamine derivatives in three of the most commonly collected Psilocybe species (P. cubensis, P. cyanescens, and P. semilanceata) is highly variable and unstable in museum specimens spanning multiple decades, and our study generates the first-ever insight into the highly complex and largely uncharacterized metabolomic profile for the most commonly cultivated magic mushroom, P. cubensis.

Characterization of the Gateway Decarboxylase for Psilocybin Biosynthesis

The l-tryptophan decarboxylase PsiD catalyzes the initial step of the metabolic cascade to psilocybin, the major indoleethylamine natural product of the "magic" mushrooms and a candidate drug against major depressive disorder. Unlike numerous pyridoxal phosphate (PLP)-dependent decarboxylases for natural product biosyntheses, PsiD is PLP-independent and resembles type II phosphatidylserine decarboxylases. Here, we report on the in vitro biochemical characterization of Psilocybe cubensis PsiD along with in silico modeling of the PsiD structure. A non-canonical serine protease triad for autocatalytic cleavage of the pro-protein was predicted and experimentally verified by site-directed mutagenesis.

Psilocybin containing mushrooms: a rapidly developing biotechnology industry in the psychiatry, biomedical and nutraceutical fields

Humans have collected and used hallucinogenic mushrooms for ethnic medicinal, recreational, and religious purposes since before recorded history. Currently, the use of these mushrooms is illegal in most countries, but where their use is legal they are applied as self medication. Psilocybin and psilocin, two psychoactive alkaloids, are naturally synthesized by hallucinogenic mushrooms. The chemical structure of these compounds are similar to the neurotransmitter serotonin. Activation of this system by psilocybin and psilocin may produce temporary changes in the brain that induce hallucinations and feelings of euphoria. Adjustment of the serotonin system in this way can moderate symptoms of related mental disorders. This review summarizes relevant and current information regarding the discovery of hallucinogenic mushrooms and their contained psychoactive compounds, the events that lead to their criminalization and decriminilization, and the state of knowledge of psilocybin, psilocin, and derivatives. Last, research on the psychoactive properties of these mushrooms is placed in perspective to possible applications for human dysfunctions.

Extensive Collection of Psychotropic Mushrooms with Determination of Their Tryptamine Alkaloids

Since not only psilocybin (PSB) but also PSB-containing mushrooms are used for psychedelic therapy and microdosing, it is necessary to know their concentration variability in wild-grown mushrooms. This article aimed to determine the PSB, psilocin (PS), baeocystin (BA), norbaeocystin (NB), and aeruginascin (AE) concentrations in a large sample set of mushrooms belonging to genera previously reported to contain psychotropic tryptamines. Ultra-high performance liquid chromatography coupled with tandem mass spectrometry was used to quantify tryptamine alkaloids in the mushroom samples. Most mushroom collections were documented by fungarium specimens and/or ITS rDNA/LSU/EF1-α sequencing. Concentrations of five tryptamine alkaloids were determined in a large sample set of 226 fruiting bodies of 82 individual collections from seven mushroom genera. For many mushroom species, concentrations of BA, NB, and AE are reported for the first time. The highest PSB/PS concentrations were found in Psilocybe species, but no tryptamines were detected in the P. fuscofulva and P. fimetaria collections. The tryptamine concentrations in mushrooms are extremely variable, representing a problem for mushroom consumers due to the apparent risk of overdose. The varied cocktail of tryptamines in wild mushrooms could influence the medicinal effect compared to therapy with chemically pure PSB, posing a serious problem for data interpretation.

Potential Therapeutic Effects of Psilocybin: A Systematic Review

Psilocybin is a plant alkaloid that is derived from precursors of tryptamine and is present in many different types of mushrooms. It has been utilized by indigenous peoples of Central and South America for centuries in a ceremonial setting to promote spiritual experiences. Indigenous societies have long employed psilocybin and other 5-HT 2A agonist classic psychedelics in their rites. They were a focus in psychiatry in the middle of the 20th century as both experimental medicines and tools for studying brain function. Due to the fact that traditional psychedelics were being used for purposes other than medical research and in connection with the burgeoning counterculture by the late 1960s and early 1970s, these scientific investigations fell out of favor. However, thanks to a number of encouraging studies that validated the earlier research, interest in traditional psychedelics has surged among scientists in the 21st century. In this review, we examine therapeutic studies on psilocybin, the traditional psychedelic that has received the lion's share of recent attention. According to three controlled studies, psilocybin may reduce symptoms of depression and anxiety in the context of cancer-related psychological discomfort for at least six months after a single acute treatment for mood and anxiety disorders. Three months after two acute doses, individuals in a small, open-label study with treatment-resistant depression reported fewer depressive and anxiety symptoms. Small, open-label pilot studies on addiction have demonstrated encouraging success rates for alcohol and cigarette addiction. The review also briefly discusses the synthesis, mechanism of action, effects, molecular pharmacology, adverse effects, and contraindications of psilocybin.

Neural Mechanisms and Psychology of Psychedelic Ego Dissolution

Neuroimaging studies of psychedelics have advanced our understanding of hierarchical brain organization and the mechanisms underlying their subjective and therapeutic effects. The primary mechanism of action of classic psychedelics is binding to serotonergic 5-HT2A receptors. Agonist activity at these receptors leads to neuromodulatory changes in synaptic efficacy that can have a profound effect on hierarchical message-passing in the brain. Here, we review the cognitive and neuroimaging evidence for the effects of psychedelics: in particular, their influence on selfhood and subject-object boundaries-known as ego dissolution-surmised to underwrite their subjective and therapeutic effects. Agonism of 5-HT2A receptors, located at the apex of the cortical hierarchy, may have a particularly powerful effect on sentience and consciousness. These effects can endure well after the pharmacological half-life, suggesting that psychedelics may have effects on neural plasticity that may play a role in their therapeutic efficacy. Psychologically, this may be accompanied by a disarming of ego resistance that increases the repertoire of perceptual hypotheses and affords alternate pathways for thought and behavior, including those that undergird selfhood. We consider the interaction between serotonergic neuromodulation and sentience through the lens of hierarchical predictive coding, which speaks to the value of psychedelics in understanding how we make sense of the world and specific predictions about effective connectivity in cortical hierarchies that can be tested using functional neuroimaging. SIGNIFICANCE STATEMENT: Classic psychedelics bind to serotonergic 5-HT2A receptors. Their agonist activity at these receptors leads to neuromodulatory changes in synaptic efficacy, resulting in a profound effect on information processing in the brain. Here, we synthesize an abundance of brain imaging research with pharmacological and psychological interpretations informed by the framework of predictive coding. Moreover, predictive coding is suggested to offer more sophisticated interpretations of neuroimaging findings by bridging the role between the 5-HT2A receptors and large-scale brain networks.

Where do we go next in antidepressant drug discovery? A new generation of antidepressants: a pivotal role of AMPA receptor potentiation and mGlu2/3 receptor antagonism

INTRODUCTION

Major depressive disorder remains a prevalent world-wide health problem. Currently available antidepressant medications take weeks of dosing, do not produce antidepressant response in all patients, and have undesirable ancillary effects.

AREAS COVERED

The present opinion piece focuses on the major inroads to the creation of new antidepressants. These include N-methyl-D-aspartate (NMDA) receptor antagonists and related compounds like ketamine, psychedelic drugs like psilocybin, and muscarinic receptor antagonists like scopolamine. The preclinical and clinical pharmacological profile of these new-age antidepressant drugs is discussed.

EXPERT OPINION

Preclinical and clinical data have accumulated to predict a next generation of antidepressant medicines. In contrast to the current standard of care antidepressant drugs, these compounds differ in that they demonstrate rapid activity, often after a single dose, and effects that outlive their presence in brain. These compounds also can provide efficacy for treatment-resistant depressed patients. The mechanism of action of these compounds suggests a strong glutamatergic component that involves the facilitation of AMPA receptor function. Antagonism of mGlu2/3 receptors is also relevant to the antidepressant pharmacology of this new class of drugs. Based upon the ongoing efforts to develop these new-age antidepressants, new drug approvals are predicted in the near future.

Overcoming epistemic injustices in the biomedical study of ayahuasca: Towards ethical and sustainable regulation

After decades of biomedical research on ayahuasca's molecular compounds and their physiological effects, recent clinical trials show evidence of therapeutic potential for depression. However, indigenous peoples have been using ayahuasca therapeutically for a very long time, and thus we question the epistemic authority attributed to scientific studies, proposing that epistemic injustices were committed with practical, cultural, social, and legal consequences. We question epistemic authority based on the double-blind design, the molecularization discourse, and contextual issues about safety. We propose a new approach to foster epistemically fair research, outlining how to enforce indigenous rights, considering the Brazilian, Peruvian, and Colombian cases. Indigenous peoples have the right to maintain, control, protect, and develop their biocultural heritage, traditional knowledge, and cultural expressions, including traditional medicine practices. New regulations about ayahuasca must respect the free, prior, and informed consent of indigenous peoples according to the International Labor Organization Indigenous and Tribal Peoples Convention no. 169. The declaration of the ayahuasca complex as a national cultural heritage may prevent patenting from third parties, fostering the development of traditional medicine. When involving isolated compounds derived from traditional knowledge, benefit-sharing agreements are mandatory according to the United Nations' Convention on Biological Diversity. Considering the extremely high demand to treat millions of depressed patients, the medicalization of ayahuasca without adequate regulation respectful of indigenous rights can be detrimental to indigenous peoples and their management of local environments, potentially harming the sustainability of the plants and of the Amazon itself, which is approaching its dieback tipping point.

Psilocybin use patterns and perception of risk among a cohort of Black individuals with Opioid Use Disorder

Background and aims

There is growing evidence that psilocybin, a serotonergic psychedelic substance, may be useful in the treatment of substance use disorders. However, there is a lack of data on the beliefs and attitudes towards psilocybin amongst Black individuals diagnosed with Opioid Use Disorder (OUD). This study characterized psilocybin use patterns and perception of risk amongst a cohort of Black individuals diagnosed with OUD.

Methods

Using a convenience sampling approach, patients were recruited from an urban methadone treatment program and paid five dollars to complete an anonymous phone-based survey.

Results

Twenty-eight patients participated (mean age 53.8; N = 28; 35.7% female). Most (N = 23; 82.1%) had "heard of" psilocybin mushrooms before taking the survey, but only five (N = 5; 17.8%) had ever used them. More than 80% perceived a risk or were "unsure" of the risk for sixteen of the seventeen items queried about psilocybin. Approximately half (N = 15; 53.6%) were willing to try therapy incorporating psilocybin and half (N = 14; 50%) said they would be more likely to try if it were FDA approved for OUD. Most (N = 18; 64.3%) preferred to stay on methadone treatment alone, 32.1% (N = 9) wanted to try treatment with both psilocybin and methadone, and only one participant opted for psilocybin treatment without methadone.

Conclusion

Many Black individuals with Opioid Use Disorder perceive psilocybin as dangerous and may be hesitant to try psilocybin treatment. Culturally informed treatment models, educational interventions and community outreach programs should be developed to increase racial/ethnic minority representation in psilocybin research and treatment.

Postpartum depression: A role for psychedelics?

BACKGROUND

Postpartum depression (PPD) is a major public health concern and has, at its core, a sense of maternal 'disconnection' - from the self, the infant, and the support system. While PPD bears similarities with MDD, there is increasing evidence for its distinct nature, especially with the unique aspect of the mother-infant relationship. Current treatment modalities for PPD, largely based on those used in major depressive disorder (MDD), have low remission rates with emerging evidence for treatment resistance. It is, therefore, necessary to explore alternative avenues of treatment for PPD.

OBJECTIVE

In this narrative review, we outline the potential therapeutic rationale for serotonergic psychedelics in the treatment of PPD, and highlight safety and pragmatic considerations for the use of psychedelics in the postpartum period.

METHODS

We examined the available evidence for the treatment of PPD and the evidence for psychedelics in the treatment of MDD. We explored safety considerations in the use of psychedelics in the postpartum period.

RESULTS

There is increasing evidence for safety, and encouraging signals for efficacy, of psilocybin in the treatment of MDD. Psilocybin has been shown to catalyse a sense of 'reconnection' in participants with MDD. This effect in PPD, by fostering a sense of 'reconnection' for the mother, may allow for improved mood and maternal sensitivity towards the infant, which can positively impact maternal role gratification and the mother-infant relationship.

CONCLUSION

Psychedelic assisted therapy in PPD may have a positive effect on the mother-infant dyad and warrants further examination.

Genetic Survey of Psilocybe Natural Products

Psilocybe magic mushrooms are best known for their main natural product, psilocybin, and its dephosphorylated congener, the psychedelic metabolite psilocin. Beyond tryptamines, the secondary metabolome of these fungi is poorly understood. The genomes of five species (P. azurescens, P. cubensis, P. cyanescens, P. mexicana, and P. serbica) were browsed to understand more profoundly common and species-specific metabolic capacities. The genomic analyses revealed a much greater and yet unexplored metabolic diversity than evident from parallel chemical analyses. P. cyanescens and P. mexicana were identified as aeruginascin producers. Lumichrome and verpacamide A were also detected as Psilocybe metabolites. The observations concerning the potential secondary metabolome of this fungal genus support pharmacological and toxicological efforts to find a rational basis for yet elusive phenomena, such as paralytic effects, attributed to consumption of some magic mushrooms.