Expectancy in placebo-controlled trials of psychedelics: if so, so what?

(R)-(-)-Ketamine: The Promise of a Novel Treatment for Psychiatric and Neurological Disorders

NMDA receptor antagonists have potential for therapeutics in neurological and psychiatric diseases, including neurodegenerative diseases, epilepsy, traumatic brain injury, substance abuse disorder (SUD), and major depressive disorder (MDD). (S)-ketamine was the first of a novel class of antidepressants, rapid-acting antidepressants, to be approved for medical use. The stereoisomer, (R)-ketamine (arketamine), is currently under development for treatment-resistant depression (TRD). The compound has demonstrated efficacy in multiple animal models. Two clinical studies disclosed efficacy in TRD and bipolar depression. A study by the drug sponsor recently failed to reach a priori clinical endpoints but post hoc analysis revealed efficacy. The clinical value of (R)-ketamine is supported by experimental data in humans and rodents, showing that it is less sedating, does not produce marked psychotomimetic or dissociative effects, has less abuse potential than (S)-ketamine, and produces efficacy in animal models of a range of neurological and psychiatric disorders. The mechanisms of action of the antidepressant effects of (R)-ketamine are hypothesized to be due to NMDA receptor antagonism and/or non-NMDA receptor mechanisms. We suggest that further clinical experimentation with (R)-ketamine will create novel and improved medicines for some of the neurological and psychiatric disorders that are underserved by current medications.

In the new era of psychedelic assisted therapy: A systematic review of study methodology in randomized controlled trials

Recent years have seen a resurgence in randomized, placebo controlled trials (RCTs) utilizing non-classical psychedelics (e.g. 3,4-methyl enedioxy methamphetamine [MDMA]), and classical psychedelics (e.g. psilocybin, lysergic acid diethylamide [LSD], and N,N-dimethyltryptamine [DMT/ayahuasca]) in conjunction with assisted therapy (AT) for psychiatric disorders. A notable methodological challenge in psychedelic AT, however, is the complexity of blinding procedures. The lack of efficacious blinding can introduce considerable response bias, reduce internal validity, and compromise participant retention. This systematic review examines design and blinding techniques in RCTs utilizing psychedelics and placebo for the treatment of psychiatric disorders. The aim of this work is to identify factors that may inform future RTC design for conducting psychedelics research. We conducted a systematic review of PubMed, MEDLINE, CINAHL, Cochrane Central Register of Controlled Trials (CENTRAL), Psycinfo, Embase, and Web of Science Core Collection to examine: (1) placebo selection, (2) study design, and (3) integrity of blinding measures. Sixteen publications were identified as meeting the criteria for a systematic review. Our findings suggest that traditional placebo administration is insufficient to control for expectancy confounds. Consequently, experimental methodology that limits personnel unblinding and the use of an active placebo are important considerations when designing prospective clinical studies involving psychedelics.

Evidence versus expectancy: the development of psilocybin therapy

SUMMARY

Although the development of psilocybin therapy has come as a surprise to many, modern research with the drug has been ongoing for 25 years. Psilocybin therapy is composed of psilocybin dosing sessions embedded within a wider process of psychoeducation, psychological support and integration. Early phase clinical trial evidence is promising, particularly for treatment-resistant depression. However, masking probably fails and expectancy effects may be a part of the mechanism of change. Disambiguating between drug and expectancy effects is a necessary part of the development process, yet this is difficult if masking fails. Hitherto, masking and expectancy have not been routinely measured in psilocybin or other medication trials. Doing so represents an opportunity for research and may influence psychiatry more widely. In this opinion piece I summarise the clinical development process of psilocybin therapy thus far, discussing the hope, the hype, the challenges and the opportunities along the way.

Psychedelic Therapy: A Primer for Primary Care Clinicians-Historical Perspective and Overview

BACKGROUND

Psychedelic drugs have recently emerged as plausibly effective pharmacological agents for the management of depression, anxiety, and other neuropsychiatric conditions, including those that are treatment-resistent. The latter half of the 20th century marked a revolution in the treatment of mental illnesses, exemplified by the introduction of selective serotonin reuptake inhibitors and other pharmacological agents. Nevertheless, mental illness remains a major public health crisis, affecting nearly one billion individuals worldwide.

AREAS OF UNCERTAINTY

Because of the decades-long status of several psychedelics as Schedule I drugs, there have not been very many large, double-blind, randomized controlled trials of psychedelics. Owing to small sample sizes, there may be rare yet serious adverse events that have not been reported in the clinical trials thus far.

THERAPEUTIC ADVANCES

Esketamine, a dissociative hallucinogen drug, was approved for the management of major depressive disorder by the Food and Drug Administration in 2019. As of January 2024, two Phase III trials of 3,4-methylenedioxymethamphetamine (MDMA), a synthetic drug that inhibits the serotonin transporter, have been completed; the results indicate that MDMA is superior to existing pharmacological treatments for post-traumatic stress disorder. A phase III trial of psilocybin, a naturally occurring serotonin receptor partial agonist, is currently underway. The following series details the current state of research in psychedelic therapeutics, including lysergic acid diethylamide (LSD), N-N-dimethyltryptamine (DMT) and ayahuasca, psilocybin, ibogaine, MDMA, and ketamine.

LIMITATIONS

While initial clinical trials of psychedelics for depression were very promising, trials of psilocybin with larger sample sizes (100+ participants) suggest that its remission rate is 25%-29%. This is about the same as the remission rate of antidepressants, which is roughly 30% according to the landmark STAR*D trial.

CONCLUSIONS

Psychedelic drugs and structural derivatives offer a great deal of promise for the management of a wide range of psychiatric morbidities. It is imperative that clinicians become familiar with these novel agents and learn how to integrate psychedelic therapy with the rest of their care through open communication and referral.

Patient perspectives and experiences with psilocybin treatment for treatment-resistant depression: a qualitative study

Psilocybin is the most researched classic psychedelic for Treatment-Resistant Depression (TRD). While optimizing set and setting are considered essential for efficacy and safety, patient perspectives on these aspects have rarely been investigated. To address this knowledge gap, the current paper explored the experiences of 11 TRD patients (8 women, 3 men) participating in a double-blind randomized clinical trial with a single session of oral (1, 10 or 25 mg) psilocybin treatment. After qualitative analysis, three major themes were identified: (1) challenges with trust-building and expectation management; (2) navigating the experience; and (3) the need for a more comprehensive treatment. Subthemes of the first theme include a general distrust in mental healthcare, trust in study therapists, limited time for preparation, and managing expectations. The second theme included the following subthemes: trusting to surrender, profound and overwhelming experiences, and music as a guide. The third theme addressed a desire for multiple psilocybin sessions, and challenges with sensemaking. Patients' perspectives provided important insights into potential optimization of psilocybin treatment of TRD, including individualized preparation, investment in trust-building, offering additional psilocybin sessions, providing access to sustained (psycho)therapy with trusted therapists, and personalizing treatment approaches, which may also enhance real-world adaption of these treatments.

The development of psilocybin therapy for treatment-resistant depression: an update

Psilocybin is a classic psychedelic drug that has attracted increasing research interest over the past 10 years as a possible treatment for mood, anxiety and related conditions. Initial phase 2 clinical trials of psilocybin given alongside psychological support for major depression and treatment-resistant depression (TRD) demonstrated encouraging signs of basic safety, further confirmed by a large study in groups of healthy volunteers. The first international multi-centre randomised controlled trial was published in 2022, with signs of efficacy for the 25 mg dose condition in people with TRD when compared with an active placebo. Phase 3 trials in TRD are scheduled to start in 2023. Early evidence suggests that single doses of psilocybin given with psychological support induce rapid improvement in depressive symptoms that endure for some weeks. We therefore provide a timely update to psychiatrists on what psilocybin therapy is, what it is not, and the current state of the evidence-base.

Trauma-Informed Care in Psychedelic Therapy Research: A Qualitative Literature Review of Evidence-Based Psychotherapy Interventions in PTSD and Psychedelic Therapy Across Conditions

Introduction

Post-traumatic stress disorder (PTSD) is associated with significant patient burden. While pharmacotherapies and evidence-based psychotherapy interventions (EBPI) are effective, studies consistently highlight inadequate outcomes and high treatment dropout. Psychedelic therapy (PT) has shown preliminary promise across difficult-to-treat conditions, including MDMA-assisted therapy for PTSD, however trials of classical psychedelics in PTSD are lacking. Understanding patients' experiences of EBPI could help promote safety in PT.

Aim

To systematically review qualitative research on patients' subjective experience of EBPI for PTSD, and of PT, and examine areas of overlap and divergence between them.

Methods

Systematic literature searches for studies published between 2010 and 2023 were conducted on OVID, PubMed, Web of Science, and PsycInfo. Included were original studies in English that presented qualitative data of patient experiences of EBPI in PTSD, or PT for any indication. Extracted data from included studies were analysed using thematic synthesis. Syntheses were completed separately for EBPI and PT, before similarities and differences between the therapies were identified.

Results

40 research articles were included for review: 26 studies on EBPI for PTSD, and 14 studies on PT. EBPI studied were CBT, EMDR, CPT and PE. Psychedelic compounds studied were psilocybin, ibogaine, LSD, MDMA and ketamine, for treatment of substance use disorders, anxiety relating to physical illness, depression, and PTSD. Core themes from patient experiences of EBPI: 1) patient burden in PTSD treatment; 2) readiness; 3) key mechanisms of change; 4) psychological safety and trust. Themes identified in the review of PT: 1) indirect trauma processing; 2) reorganisation of self-narratives via processes of relatedness and identification; 3) key treatment characteristics.

Conclusion

This study suggests overlap between patients' experience of EBPI and PT in terms of key mechanisms of change, the importance of psychological safety and readiness to engage in treatment. Trauma-informed care paradigms and practices may improve safety and acceptability of PT research.

Set and setting predict psychopathology, wellbeing and meaningfulness of psychedelic experiences: a correlational study

BACKGROUND

In psychedelic therapy, the importance of set and setting is a fundamental but under-researched assumption. The aim of this study is to correlate variables of set (psychedelic use motivation) and setting (psychedelic use location and type of companion) with psychopathology, wellbeing and personality variables.

RESEARCH DESIGN AND METHODS

A sample of 1022 participants of the Spanish-speaking population was collected through an online survey. A novel instrument, the Psychedelic Use Scale (PUS), was developed to measure substance use variables of LSD, mescaline, psilocybin, DMT, 5-Meo-DMT, ketamine, Salvia divinorum, ibogaine and MDMA. Various personality, well-being and psychopathology instruments were implemented to measure outcome variables.

RESULTS

Growth motivations, natural settings and presence of significant others predicted less psychopathology, greater wellbeing and meaningfulness of psychedelic experiences, whereas problematic motivations predicted greater psychopathology, lower wellbeing and did not predict meaningfulness of psychedelic experiences.

CONCLUSIONS

Based on these results, we suggest experimental hypotheses for future clinical trials and longitudinal studies with potential clinical implications.

The new European Medicines Agency guideline on antidepressants: a guide for researchers and drug developers

According to the World Health Organization (WHO), depressive disorders are currently considered as one of the most disabling medical conditions in the world with one of the highest disability-adjusted life years [1] and this situation has apparently been further worsened during the COVID-19 pandemic [2]. Up to two thirds of patients with major depressive disorders (MDD) do not achieve full remission following an adequate first line standard of care and/or experience residual symptoms such as anxiety, impaired cognition, fatigue, sleep disturbance, or anhedonia [3]. Several attempts are often needed to find the most suitable treatment [4]. Thus, there is a need for medicinal products with better efficacy (e.g., faster onset of action, higher rates of response and remission), improved safety and/or more personalised profiles [5].

Mindfulness meditation and psychedelics: potential synergies and commonalities

There has been increasing scientific and clinical interest in studying psychedelic and meditation-based interventions in recent years, both in the context of improving mental health and as tools for understanding the mind. Several authors suggest neurophysiological and phenomenological parallels and overlaps between psychedelic and meditative states and suggest synergistic effects of both methods. Both psychedelic-assisted therapy and meditation training in the form of mindfulness-based interventions have been experimentally validated with moderate to large effects as alternative treatments for a variety of mental health problems, including depression, addictions, and anxiety disorders. Both demonstrated significant post-acute and long-term decreases in clinical symptoms and enhancements in well-being in healthy participants, in addition. Postulated shared salutogenic mechanisms, include, among others the ability to alter self-consciousness, present-moment awareness and antidepressant action via corresponding neuromodulatory effects. These shared mechanisms between mindfulness training and psychedelic intervention have led to scientists theorizing, and recently demonstrating, positive synergistic effects when both are used in combination. Research findings suggest that these two approaches can complement each other, enhancing the positive effects of both interventions. However, more theoretical accounts and methodologically sound research are needed before they can be extended into clinical practice. The current review aims to discuss the theoretical rationale of combining psychedelics with mindfulness training, including the predictive coding framework as well as research findings regarding synergies and commonalities between mindfulness training and psychedelic intervention. In addition, suggestions how to combine the two modalities are provided.

Psilocybin as a lead candidate molecule in preclinical therapeutic studies of psychiatric disorders: A systematic review

Psilocybin is the main psychoactive compound found in hallucinogenic/magic mushrooms and can bind to both serotonergic and tropomyosin receptor kinase b (TrkB) receptors. Psilocybin has begun to show efficacy for a range of neuropsychiatric conditions, including treatment-resistant depression and anxiety disorders; however, neurobiological mechanisms are still being elucidated. Clinical research has found that psilocybin can alter functional connectivity patterns in human brains, which is often associated with therapeutic outcomes. However, preclinical research affords the opportunity to assess the potential cellular mechanisms by which psilocybin may exert its therapeutic effects. Preclinical rodent models can also facilitate a more tightly controlled experimental context and minimise placebo effects. Furthermore, where there is a rationale, preclinical researchers can investigate psilocybin administration in neuropsychiatric conditions that have not yet been researched clinically. As a result, we have systematically reviewed the knowledge base, identifying 82 preclinical studies which were screened based on specific criteria. This resulted in the exclusion of 44 articles, with 34 articles being included in the main review and another 2 articles included as Supporting Information materials. We found that psilocybin shows promise as a lead candidate molecule for treating a variety of neuropsychiatric conditions, albeit showing the most efficacy for depression. We discuss the experimental findings, and identify possible mechanisms whereby psilocybin could invoke therapeutic changes. Furthermore, we critically evaluate the between-study heterogeneity and possible future research avenues. Our review suggests that preclinical rodent models can provide valid and translatable tools for researching novel psilocybin-induced molecular and cellular mechanisms, and therapeutic outcomes.

Psilocybin and Other Classic Psychedelics in Depression

Psychedelic drugs such as psilocybin and ketamine are returning to clinical research and intervention across several disorders including the treatment of depression. This chapter focusses on psychedelics that specifically target the 5-HT2A receptor such as psilocybin and DMT. These produce plasma-concentration related psychological effects such as hallucinations and out of body experiences, insightful and emotional breakthroughs as well as mystical-type experiences. When coupled with psychological support, effects can produce a rapid improvement in mood among people with depression that can last for months. In this chapter, we summarise the scientific studies to date that explore the use of psychedelics in depressed individuals, highlighting key clinical, psychological and neuroimaging features of psychedelics that may account for their therapeutic effects. These include alterations in brain entropy that disrupt fixed negative ruminations, a period of post-treatment increased cognitive flexibility, and changes in self-referential psychological processes. Finally, we propose that the brain mechanisms underlying the therapeutic effect of serotonergic psychedelics might be distinct from those underlying classical serotonin reuptake-blocking antidepressants.

Psilocybin-assisted therapy for depression: A systematic review and dose-response meta-analysis of human studies

Psilocybin is increasingly studied for its antidepressant effect, but its optimal dosage for depression remains unclear. We conducted a systematic review and a dose-response meta-analysis to find the optimal dosage of psilocybin to reduce depression scores. Following our protocol (CRD 42022220190) multiple electronic databases were searched from their inception until February 2023, to identify double-blind randomized placebo-controlled (RCTs) fixed-dose trials evaluating the use of psilocybin for adult patients with primary or secondary depression. A one-stage dose-response meta-analysis with restricted cubic splines was used. Cochrane risk of bias was used to assess risk of bias. Our analysis included seven studies with a total of 489 participants. Among these, four studies focused on primary depression (N = 366), including one study with patients suffering from treatment-resistant depression. The remaining three studies examined secondary depression (N = 123). The determined 95% effective doses per day (ED95) were 8.92, 24.68, and 36.08 mg/70 kg for patients with secondary depression, primary depression, and both subgroups, respectively. We observed significant dose-response associations for all curves, each plateauing at different levels, except for the bell-shaped curve observed in the case of secondary depression. Additionally, we found significant dose-response associations for various side effects, including physical discomfort, blood pressure increase, nausea/vomiting, headache/migraine, and the risk of prolonged psychosis. In conclusion, we discovered specific ED95 values for different populations, indicating higher ED95 values for treatment-resistant depression, primary depression, and secondary depression groups. Further RCTs are necessary for each population to determine the optimal dosage, allowing for maximum efficacy while minimizing side effects.

Randomized trial of ketamine masked by surgical anesthesia in patients with depression

Ketamine may have antidepressant properties, but its acute psychoactive effects complicate successful masking in placebo-controlled trials. We present a single-center, parallel-arm, triple-masked, randomized, placebo-controlled trial assessing the antidepressant efficacy of intravenous ketamine masked by surgical anesthesia (ClinicalTrials.gov, NCT03861988). Forty adult patients with major depressive disorder who were scheduled for routine surgery were randomized to a single infusion of ketamine (0.5 mg/kg) or placebo (saline) during usual anesthesia. All participants, investigators, and direct patient care staff were masked to treatment allocation. The primary outcome was depression severity measured by the Montgomery-Åsberg Depression Rating Scale (MADRS) at 1, 2, and 3 days post-infusion. After all follow-up visits, participants were asked to guess which intervention they received. A mixed-effects model showed no evidence of effect of treatment assignment on the primary outcome (-5.82, 95% CI -13.3 to 1.64, p=0.13). 36.8% of participants guessed their treatment assignment correctly; both groups allocated their guesses in similar proportions. In conclusion, a single dose of intravenous ketamine delivered during surgical anesthesia had no greater effect than placebo in acutely reducing the severity of depressive symptoms in adults with major depressive disorder. This trial successfully masked treatment allocation in moderate-to-severely depressed patients using surgical anesthesia. Although this masking strategy is impractical for most placebo-controlled trials, future studies of novel antidepressants with acute psychoactive effects should make efforts to fully mask treatment assignment in order to minimize subject-expectancy bias.

Dark loops: contagion effects, consistency and chemosocial matrices in psychedelic-assisted therapy trials

What happens when an emerging programme of medical research overlaps with a surging social movement? In this article we draw on the anthropological term 'chemosociality' to describe forms of sociality born of shared chemical exposure. Psychedelic administration in the context of recent clinical trials appears to have been particularly chemosocial in nature. We argue that one consequence is that psychedelic-assisted therapy (PAT) clinical research trials tend to breach key assumptions underlying the logic of causal inference used to establish efficacy. We propose the concept of dark loops to describe forms of sociality variously emerging from, and impacting participant experiences in, PAT trials. These dark loops are not recorded, let alone incorporated into the causal pathways in the interpretation of psychedelic trial data to date. We end with three positions which researchers might adopt in response to these issues: chemosocial minimisation where research is designed to attenuate or eliminate the effects of dark loops in trials; chemosocial description where dark loops (and their impacts) are openly and candidly documented and chemosocial valorisation where dark loops are hypothesised to contribute to trial outcomes and actively drawn upon for positive effect. Our goal is to fold in an appreciation of how the increasingly-discussed hype surrounding psychedelic research and therapeutics continues to shape the phenomena under study in complex ways, even as trials become larger and more rigorous in their design.

Psychedelics for treatment resistant depression: are they game changers?

INTRODUCTION

A new era of treatment for adults with treatment-resistant depression (TRD), which involves psychedelic substances, is dawning. Emerging evidence indicates that psychedelics can exert antidepressant effects through multiple neurobiological and psychological mechanisms. However, it remains to be seen if these new treatments will revolutionize the treatment of TRD.

AREAS COVERED

The present review focuses on the efficacy of serotoninergic psychedelics psilocybin, lysergic acid diethylamide (LSD), N,N-dimethyltryptamine (DMT), ayahuasca, 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) and mescaline (3,4,5-trimethoxyphenethylamine), as well as 3,4-methylenedioxymethamphetamine (MDMA), for TRD. A systematic search was conducted for psilocybin in TRD as emerging trials had not yet been subject to review. A narrative review summarized findings on other psychedelics.

EXPERT OPINION

Psychedelic therapy has created a paradigm shift in the treatment of TRD, as it can maximize therapeutic benefits and minimize potential risks. Psilocybin holds promise as a potential game-changer in the treatment of TRD, with initial evidence suggesting a rapid antidepressant effect sustained for some responders for at least 3 months. Nevertheless, further adequately powered, double-blind, comparator-controlled trials are required to explore and clarify the mechanisms of action and long-term effects of psychedelics in TRD. Psychedelics also hold promise for other psychiatric conditions, such as bipolar depression and post-traumatic stress disorder.

Mechanisms and molecular targets surrounding the potential therapeutic effects of psychedelics

Psychedelics, also known as classical hallucinogens, have been investigated for decades due to their potential therapeutic effects in the treatment of neuropsychiatric and substance use disorders. The results from clinical trials have shown promise for the use of psychedelics to alleviate symptoms of depression and anxiety, as well as to promote substantial decreases in the use of nicotine and alcohol. While these studies provide compelling evidence for the powerful subjective experience and prolonged therapeutic adaptations, the underlying molecular reasons for these robust and clinically meaningful improvements are still poorly understood. Preclinical studies assessing the targets and circuitry of the post-acute effects of classical psychedelics are ongoing. Current literature is split between a serotonin 5-HT2A receptor (5-HT2AR)-dependent or -independent signaling pathway, as researchers are attempting to harness the mechanisms behind the sustained post-acute therapeutically relevant effects. A combination of molecular, behavioral, and genetic techniques in neuropharmacology has begun to show promise for elucidating these mechanisms. As the field progresses, increasing evidence points towards the importance of the subjective experience induced by psychedelic-assisted therapy, but without further cross validation between clinical and preclinical research, the why behind the experience and its translational validity may be lost.

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.

Depression and anxiety in glioma patients

AbstractGlioma patients carry the burden of having both a progressive neurological disease and cancer, and may face a variety of symptoms, including depression and anxiety. These symptoms are highly prevalent in glioma patients (median point prevalence ranging from 16-41% for depression and 24-48% for anxiety when assessed by self-report questionnaires) and have a major impact on health-related quality of life and even overall survival time. A worse overall survival time for glioma patients with depressive symptoms might be due to tumor progression and/or its supportive treatment causing depressive symptoms, an increased risk of suicide or other (unknown) factors. Much is still unclear about the etiology of depressive and anxiety symptoms in glioma. These psychiatric symptoms often find their cause in a combination of neurophysiological and psychological factors, such as the tumor and/or its treatment. Although these patients have a particular idiosyncrasy, standard treatment guidelines for depressive and anxiety disorders apply, generally recommending psychological and pharmacological treatment. Only a few nonpharmacological trials have been conducted evaluating the efficacy of psychological treatments (eg, a reminiscence therapy-based care program) in this population, which significantly reduced depressive and anxiety symptoms. No pharmacological trials have been conducted in glioma patients specifically. More well-designed trials evaluating the efficacy of nonpharmacological treatments for depressive and anxiety disorders in glioma are urgently needed to successfully treat psychiatric symptoms in brain tumor patients and to improve (health-related) quality of life.

Examining the Psychoactive Differences between Kratom Strains

Kratom (Mitragyna speciosa) is a Southeast Asian plant containing various alkaloids that induce pharmacological effects in humans. In Western countries, online vendors sell a variety of different kratom strains which are marketed to have distinct effect profiles. However, as of yet such marketing claims are unsubstantiated, and therefore the current study investigated whether differently colored kratom products can induce distinct effects, as self-reported by users. Six hundred forty-four current kratom users were anonymously surveyed to compare the self-reported effects of and motivations for using kratom products sold as red, green, and white strains. Most of the survey respondents were customers of the same kratom vendor, the products of which had been analyzed for their alkaloid content by an independent laboratory. The survey respondents reported distinct subjective experiences for different kratom strains, in a manner congruent with common marketing descriptions. However, the product analyses revealed no significant cross-strain differences in alkaloid content, suggesting that the reported effect differences might be disproportionally influenced by marketing narratives and anecdotal reports. Future studies should engage a more diverse population and include kratom strains from various vendors. Controlled, blinded experiments could assess whether the reported effect differences stem from a placebo effect or from alternative factors, e.g., minor alkaloids and terpenes.

Overcoming blinding confounds in psychedelic randomized controlled trials using biomarker driven causal mediation analysis

INTRODUCTION

There is great interest in the use of psychedelic-assisted therapies to treat a range of mental health conditions and initial randomized controlled trials (RCTs) have generated positive results. However, the effect sizes reported in psychedelic RCTs are likely inflated due to expectancy effects due to the de-blinding of both participants and study personnel to treatment allocation caused by the distinctive psychoactive effects of psychedelic drugs.

AREAS COVERED

An introduction to causal inference for RCTs, the underlying assumptions, and potential confounders along with graphical illustrations is provided. It is proposed that causal mediation analysis using objectively measured mediating biomarkers could be used to identify causal pathways between treatment and outcome in psychedelic RCTs, even with de-blinding of participants and give greater confidence as to the mechanistic basis and efficacy of psychedelic therapies.

EXPERT OPINION

It is argued that psychedelic therapies should not be approved as licensed medicines until causal pathways are clearly established between treatment and outcome. Potential downsides of doing so include, future indication expansion based on low quality clinical trial evidence, the approval of other therapies based on similarly low-quality evidence, and the potential for efficacy to change over time after approvals has been granted.

Randomized Trial of Ketamine Masked by Surgical Anesthesia in Depressed Patients

BACKGROUND

Ketamine may have antidepressant properties, but its acute psychoactive effects complicate successful masking in placebo-controlled trials.

METHODS

In a triple-masked, randomized, placebo-controlled trial, 40 adult patients with major depressive disorder were randomized to a single infusion of ketamine (0.5 mg/kg) or placebo (saline) during anesthesia as usual for routine surgery. The primary outcome was depression severity measured by the Montgomery-Åsberg Depression Rating Scale (MADRS) at 1, 2, and 3 days post-infusion. The secondary outcome was the proportion of participants with clinical response (≥50% reduction in MADRS scores) at 1, 2, and 3 days post-infusion. After all follow-up visits, participants were asked to guess which intervention they received.

RESULTS

Mean MADRS scores did not differ between groups at screening or pre-infusion baseline. The mixed-effects model showed no evidence of effect of group assignment on post-infusion MADRS scores at 1 to 3 days post-infusion (-5.82, 95% CI -13.3 to 1.64, p=0.13). Clinical response rates were similar between groups (60% versus 50% on day 1) and comparable to previous studies of ketamine in depressed populations. Secondary and exploratory outcomes did not find statistical separation of ketamine from placebo. 36.8% of participants guessed their treatment assignment correctly; both groups allocated their guesses in similar proportions. One serious adverse event occurred in each group, unrelated to ketamine administration.

CONCLUSION

In adults with major depressive disorder, a single dose of intravenous ketamine delivered during surgical anesthesia had no greater effect than placebo in acutely reducing the severity of depressive symptoms. This trial successfully masked treatment allocation in moderate-to-severely depressed patients using surgical anesthesia. While it is impractical to use surgical anesthesia for most placebo-controlled trials, future studies of novel antidepressants with acute psychoactive effects should make efforts to fully mask treatment assignment in order to minimize subject-expectancy bias. (ClinicalTrials.gov number, NCT03861988).

The crosstalk between 5-HT2AR and mGluR2 in schizophrenia

Schizophrenia is a severe brain disorder that usually produces a lifetime of disability. First generation or typical antipsychotics such as haloperidol and second generation or atypical antipsychotics such as clozapine and risperidone remain the current standard for schizophrenia treatment. In some patients with schizophrenia, antipsychotics produce complete remission of positive symptoms, such as hallucinations and delusions. However, antipsychotic drugs are ineffective against cognitive deficits and indeed treated schizophrenia patients have small improvements or even deterioration in several cognitive domains. This underlines the need for novel and more efficient therapeutic targets for schizophrenia treatment. Serotonin and glutamate have been identified as key parts of two neurotransmitter systems involved in fundamental brain processes. Serotonin (or 5-hydroxytryptamine) 5-HT2A receptor (5-HT2AR) and metabotropic glutamate 2 receptor (mGluR2) are G protein-coupled receptors (GPCRs) that interact at epigenetic and functional levels. These two receptors can form GPCR heteromeric complexes through which their pharmacology, function and trafficking becomes affected. Here we review past and current research on the 5-HT2AR-mGluR2 heterocomplex and its potential implication in schizophrenia and antipsychotic drug action. This article is part of the Special Issue on "The receptor-receptor interaction as a new target for therapy".

Transformative experience and informed consent to psychedelic-assisted psychotherapy

Just as psychedelic-assisted psychotherapy (PAP) represents a clinical innovation that may need to be accommodated with corresponding theoretical and methodological innovations, there is growing awareness that the tools, normative frameworks, and standard practices of our clinical ethics may also need to be adapted, renewed, or replaced to accommodate its unusual features. Drawing on L. A. Paul's work on "Transformative Experience," I argue that the acute and long-term effects that are repeatedly reported following the administration of psychedelic drugs, including in clinical contexts, are epistemically inaccessible at the point of deciding to take them. By virtue of both the so-called "mystical" experiences that frequently arise during PAP, and the long-term shifts to outlooks, values, and priorities that can follow treatment, the processes of decision-making that are normatively expected of patients run aground. If this framing is correct, then prospective patients cannot meet the requirement of understanding that is one of the principal analytic components of informed consent. The role of understanding in supporting two functions of informed consent-avoiding unauthorized trespass against patients and supporting values-aligned decision-making-is explored, and I argue that, while the normative standard for the first function may be met by extant suggestions for enhancing the consenting process for PAP, the latter function remains unattainable. In light of this, the consequences for the ethical preparation of prospective patients are considered.

Unblinding and demand characteristics in the treatment of depression

Blinding of treatment allocation in clinical trials in psychiatry is regarded as an ideal. The potential impact of unblinding chimes with a general concern for psychological research: so-called demand characteristics can undermine confidence in findings from experimental and clinical studies. Scepticism can result in nihilism. The reliance on subjective report of symptoms in clinical trials of drug efficacy in depression provides an important example. It is regularly implied that if subjective effects, including specific adverse reactions, unblind participants to an active treatment then evidence for its efficacy is suspect. In fact, the strong association between dose and subjective effects does not translate into a strong relationship with efficacy in randomised controlled trials (RCTs) of conventional antidepressant drugs; this observation falsifies the proposition that unblinding is the principal mechanism driving RCT outcomes in studies of depression. Instead, changes in brain function, that occur soon after treatment starts, do predict treatment outcomes and align with our understanding of neurotransmitter effects from neuroscience. Psychedelic experience for the treatment of depression must be unblinding, but the effect results directly from serotonergic receptor activation and changes in brain connectivity. Where such effects are part of a novel mechanism of action, a strong dose response relationship would be expected, irrespective of unblinding. We highlight the importance of exploring blinding as a mechanism, confirming dose-related outcomes, and dissociating unblinding effects from efficacy. Unblinding does not necessarily invalidate the subjective experience of sustained recovery from depression.

Optimizing outcomes in psilocybin therapy: Considerations in participant evaluation and preparation

Recent studies have demonstrated the promise of psilocybin therapies in creating positive changes for those with poor mental health across multiple diagnostic categories, including major depressive disorder (MDD), end-of-life anxiety, and obsessive-compulsive disorder (OCD). While there may be a large population that is eligible to participate in psilocybin therapy based on psychiatric diagnosis and medical clearance, little attention has been given to intrapersonal and interpersonal factors that might influence patient's readiness (i.e., eligibility and capacity) for psychedelic interventions. This paper proposes that readiness assessment includes both intrapersonal and interpersonal factors in order to improve safety, patient care, and treatment outcomes. While at the present time a reliable and valid instrument has not been developed, we propose that three specific areas of focus - patient presentation, therapeutic alliance, and patient safety - may be used to establish a patient's readiness for psilocybin therapy, thus increasing therapy optimization and personalization.

The need for establishing best practices and gold standards in psychedelic medicine

Psychedelic substances are under investigation in several drug development programs. Controlled clinical trials are providing evidence for safe and effective use of psychedelic therapies for treating mental health conditions. With the anticipated FDA approval of MDMA-assisted therapy for posttraumatic stress disorder in 2023 and psilocybin therapy for depression disorders soon after, now is the time for the medical community to become informed on best practices and to actively participate in developing standards of care for these new treatments. Given the emergence of numerous drug sponsors and other companies developing therapeutic modalities for combination with psychedelic medications, it is essential that the medical professional field is at the forefront of communicating unbiased information related to safety and effectiveness. Gold standards have long been a part of medicine and serve to distinguish treatments and assessments as the highest quality by which all others can be compared to. For a treatment to be established as a gold standard, several factors are considered including the quantity and quality of the supporting data, the rigor of trials, and the safety and efficacy compared to other treatments. In this article, we review the origins of psychedelic-assisted therapy (PAT), minimum requirements for safe use of psychedelics, criteria for gold standards in mental health, and the nuances regarding how to establish gold standards in psychedelic medicine and guide clinical decision making.

Psilocybin-assisted therapy for major depressive disorder: An exploratory placebo-controlled, fixed-order trial

BACKGROUND

Several early phase studies have demonstrated that psilocybin-assisted therapy has rapid-acting and persisting antidepressant effects from just one or two doses. However, methodological limitations (e.g., placebo-control, blinding) limit interpretability of the existing literature.

METHODS

In an exploratory placebo-controlled, within-subject, fixed-order study, individuals with moderate to severe major depressive disorder were administered placebo (n = 19) followed by psilocybin (0.3 mg/kg) (n = 15) 4 weeks later. Dosing sessions were embedded within an manualized course of psychotherapy. Enhanced blinding procedures were used. Depression, anxiety, and quality of life were measured over a 16-week study period.

RESULTS

Depression and anxiety significantly improved following both placebo and psilocybin with no significant difference in the degree of change between the two conditions. However, antidepressant effect sizes were larger after psilocybin (d' = 1.02-2.27) than after placebo (d' = 0.65-0.99) and there were high rates of response (66.7%) and remission (46.7%) following psilocybin administration. Antidepressant effects following psilocybin persisted, on average, for 2 months and there were persisting improvements in mood-related quality of life domains. The strength of mystical-type experience during psilocybin dosing was not correlated with subsequent antidepressant effects.

CONCLUSIONS

The results of this exploratory study highlight the complex interplay between expectancy, therapy effects, and drug/placebo effects in psychedelic-assisted psychotherapy studies. Nonetheless, the acute and persisting clinical improvements observed following psilocybin support further study of its potential in the treatment of major depression. Future studies should more explicitly mitigate and measure expectancy effects and assess the impact of repeated dosing and different forms of psychotherapeutic support.

Investigation of self-treatment with lysergic acid diethylamide and psilocybin mushrooms: Findings from the Global Drug Survey 2020

BACKGROUND

Growing numbers of people are using psychedelics for personal psychotherapy outside clinical settings, but research on such use is scarce.

AIMS

This study investigated the patterns of use, self-reported outcomes and outcome predictors of psychedelic 'self-treatment' of mental health conditions or specific worries/concerns in life.

METHODS

We use data from the Global Drug Survey 2020, a large online survey on drug use collected between November 2019 and February 2020. In all, 3364 respondents reported their self-treatment experiences with lysergic acid diethylamide (N = 1996) or psilocybin mushrooms (N = 1368). The primary outcome of interest was the 17-item self-treatment outcome scale, items reflecting aspects of well-being, psychiatric symptoms, social-emotional skills, and health behaviours.

RESULTS

Positive changes were observed across all 17 outcome items, with the strongest benefits on items related to insight and mood. Negative effects were reported by 22.5% of respondents. High intensity of psychedelic experience, seeking advice before treatment, treating with psilocybin mushrooms and treating post-traumatic stress disorder were associated with higher scores on the self-treatment outcome scale after averaging values across all 17 items. Younger age, high intensity of experience and treating with LSD were associated with increased number of negative outcomes.

CONCLUSIONS

This study brings important insights into self-treatment practices with psychedelics in a large international sample. Outcomes were generally favourable, but negative effects appeared more frequent than in clinical settings. Our findings can help inform safe practices of psychedelic use in the community, and inspire clinical research. Future research can be improved with utilisation of prospective designs and additional predictive variables.

Psilocybin for Depression: From Credibility to Feasibility, What's Missing?

Psilocybin has been suggested as a promising transdiagnostic treatment strategy for a wide range of psychiatric disorders. Recent findings showed that psychedelic-assisted/"psycholitic" psychotherapy should provide significant and sustained alleviation of depressive symptoms. However, to date, there have been several study limitations (e.g., small sample sizes, blinding, limited follow-up, highly screened treatment populations) and some health/political issues, including practitioners' experience, lack of standardized protocols, psychedelics' legal status, ethical concerns, and potential psychological/psychopathological/medical untoward effects. The focus here is on a range of clinical and methodological issues, also aiming at outlining some possible suggestions. We are confident that newer evidence, more precise protocols, and eventual reclassification policies may allow a better understanding of the real potential of psilocybin as a transdiagnostic therapeutic molecule.