Positive expectations predict improved mental-health outcomes linked to psychedelic microdosing

Side effects of microdosing lysergic acid diethylamide and psilocybin: A systematic review of potential physiological and psychiatric outcomes

OBJECTIVE

Psychedelics are gaining renewed attention, especially through the practice of microdosing, where low doses are taken regularly. Microdosing lysergic acid diethylamide (LSD) and psilocybin is used by both healthy individuals and those with mental health conditions to improve daily functioning, reduce anxiety, and enhance mood and cognition. However, there is limited information about the side effects of this practice. This review aimed to collect and characterize the side effects of psychedelic microdosing.

METHODS

We conducted a systematic review of original papers from PubMed, Web of Science, and Scopus (accessed August 03, 2024) that reported side effects of microdosing LSD and psilocybin. Non-English papers, non-original studies, studies without typical microdosing doses, or those lacking descriptions of side effects were excluded. Our methodology has been developed in accordance with PRISMA guidelines. Because side effects were assessed heterogeneously in these papers, we did not perform a bias evaluation.

RESULTS

We included 31 studies, 15 of which we classified as laboratory studies with higher quality evidence, and 14 studies with lower quality evidence, as well as 2 clinical cases. Side effects were typically dose-dependent, mild, and short-lived. Common adverse effects included increased blood pressure, anxiety, and cognitive impairment.

DISCUSSION

This review is limited by the heterogeneity in reporting side effects and the short duration of many studies. Future studies should transparently and systematically present a description of side effects.

Effect of emotional regulation on performance of shooters during competition: An ecological momentary assessment study

OBJECTIVE

The purpose of this study was to examine the effect of emotion regulation on shooting performance in shooting athletes.

METHOD

Ecological momentary assessment was used to track and examine the dynamic relationship between pre-competition and in-competition emotions, emotion regulation strategy selection and use, and shooting performance in 57 shooting athletes.

RESULTS

Female athletes used more regulation strategies than male athletes and had lower mean shooting scores when using disengagement strategies and lower good ten-ring percentages when using engagement strategies compared to male athletes. Elite athletes had a higher percentage of ten-ring scores when using engagement strategies than did first-level athletes, but a lower percentage of ten-ring scores when using disengagement strategies. The use of emotion regulation strategies and situational demands were not strongly related. Athletes had low flexibility in emotion regulation and were better at using disengagement strategies, but disengagement strategies were not beneficial for shooting performance.

CONCLUSIONS

First-level athletes have a higher contextual demand for emotion regulation and tend to use disengagement strategies more frequently to regulate emotions. Elite-level athletes have higher average ring values and ten-ring ratios when using engagement strategies under lower contextual demand and using disengagement strategies under higher contextual demand. Enhancing flexible emotional regulation training that improves situation-strategy fit may be beneficial for enhancing sports performance.

Therapeutic Potential of Psilocybin for Treating Neuropsychiatric Long COVID Symptoms: A Reddit Investigation

Long COVID lacks effective pharmaceutical treatment options. Psychedelic treatment for long COVID has received attention given anecdotal reports of neuropsychiatric symptom improvement. This study investigates the use of psilocybin for neuropsychiatric long COVID symptoms, examining online accounts of individuals with reported long COVID using psilocybin. We searched the Reddit communities, "r/LongCovid," and "r/covidlonghaulers" for terms, "psilocybin," "shrooms," and "magic mushrooms." Posts were included if they self-reported (1) neuropsychiatric symptoms of long COVID, (2) use of psilocybin, and (3) descriptions of the perceived effect or lack thereof on long COVID symptoms. Posts were manually coded to identify the nature of psilocybin ingestion, long COVID symptoms, and post's author's perceived effect on symptoms. The most common symptoms identified were fatigue (47.3%, N = 52), cognitive impairment (46.4%, N = 51), and depression (30.0%, N = 33). Of 110 posts meeting criteria, 78.2% (N = 86) reported any improvement in long COVID symptoms, while 11.8% (N = 13) reported worsening. For those with improvement, 77.9% (N = 67) reported improvement lasting beyond their acute psychedelic experience, while 5.8% (N = 5) reported improvement only during the experience. Given these findings, studies employing comparison social media data for other long COVID self-treatments and/or prospective observational studies of individuals self-treating neuropsychiatric long COVID symptoms with psychedelics may be warranted.

Psychedelics and schizophrenia: a double-edged sword

Psychedelics have shown promising effects in several psychiatric diseases as demonstrated by multiple clinical trials. However, no clinical experiments on patients with schizophrenia have been conducted up to date, except for some old semi-anecdotal studies mainly performed in the time-span '50s-'60s. Notably, these studies reported interesting findings, particularly on the improvement of negative symptoms and social cognition. With no doubts the lack of modern clinical studies is due to the psychomimetic properties of psychedelics, a noteworthy downside that could worsen positive symptoms. However, a rapidly increasing body of evidence has suggested that the mechanisms of action of such compounds partially overlaps with the pathogenic underpinnings of schizophrenia but in an opposite way. These findings suggest that, despite being a controversial issue, the use of psychedelics in the treatment of schizophrenia would be based on a strong biological rationale. Therefore, the aim of our perspective paper is to provide a background on the old experiments with psychedelics performed on patients with schizophrenia, interpreting them in the light of recent molecular findings on their ability to induce neuroplasticity and modulate connectivity, the immune and TAARs systems, neurotransmitters, and neurotropic factors. No systematic approach was adopted in reviewing the evidence given the difficulty to retrieve and interpret old findings. Interestingly, we identified a therapeutic potential of psychedelics in schizophrenia adopting a critical point of view, particularly on negative symptoms and social cognition, and we summarized all the relevant findings. We also identified an eligible subpopulation of chronic patients predominantly burdened by negative symptoms, outlining possible therapeutic strategies which encompass very low doses of psychedelics (microdosing), carefully considering safety and feasibility, to pave the way to future clinical trials.

Multimodal creativity assessments following acute and sustained microdosing of lysergic acid diethylamide

INTRODUCTION

Enhanced creativity is often cited as an effect of microdosing (taking repeated low doses of a psychedelic drug). There have been recent efforts to validate the reported effects of microdosing, however creativity remains a difficult construct to quantify.

OBJECTIVES

The current study aimed to assess microdosing's effects on creativity using a multimodal battery of tests as part of a randomised controlled trial of microdosing lysergic acid diethylamide (LSD).

METHODS

Eighty healthy adult males were given 10 µg doses of LSD or placebo every third day for six weeks (14 total doses). Creativity tasks were administered at a drug-free baseline session, at a first dosing session during the acute phase of the drug's effects, and in a drug-free final session following the six-week microdosing regimen. Creativity tasks were the Alternate Uses Test (AUT), Remote Associates Task (RAT), Consensual Assessment Technique (CAT), and an Everyday Problem-Solving Questionnaire (EPSQ).

RESULTS

No effect of drug by time was found on the AUT, RAT, CAT, or EPSQ. Baseline vocabulary skill had a significant effect on AUT and RAT scores.

CONCLUSIONS

Despite participants reporting feeling more creative on dose days, objective measurement found no acute or durable effects of the microdosing protocol on creativity. Possible explanations of these null findings are that laboratory testing conditions may negatively affect ability to detect naturalistic differences in creative performance, the tests available do not capture the facets of creativity that are anecdotally affected by microdosing, or that reported enhancements of creativity are placebo effects.

Mushrooms, Microdosing, and Mental Illness: The Effect of Psilocybin on Neurotransmitters, Neuroinflammation, and Neuroplasticity

The incidence of mental health disorders is increasing worldwide. While there are multiple factors contributing to this problem, neuroinflammation underlies a significant subset of psychiatric conditions, particularly major depressive and anxiety disorders. Anti-inflammatory interventions have demonstrated benefit in these conditions. Psilocin, the active ingredient of mushrooms in the Psilocybe genus, is both a potent serotonin agonist and anti-inflammatory agent, increases neuroplasticity, and decreases overactivity in the default mode network. Studies using hallucinogenic doses of psilocin under the supervision of a therapist/guide have consistently demonstrated benefits to individuals with depression and end-of-life anxiety. Microdosing psilocybin in sub-hallucinogenic doses has also demonstrated benefit in mood disorders, and may offer a safe, less expensive, and more available alternative to full doses of psilocybin for mood disorders, as well as for other medical conditions in which inflammation is the principal pathophysiology.

Psychedelics for the Treatment of Psychiatric Disorders: Interpreting and Translating Available Evidence and Guidance for Future Research

During the past decade, there has been extraordinary public, media, and medical research interest in psychedelics as promising therapeutics for difficult-to-treat psychiatric disorders. Short-term controlled trial data suggest that certain psychedelics are effective and safe in the treatment of major depressive disorder, treatment-resistant depression, and posttraumatic stress disorder. Preliminary evidence also supports efficacy in other psychiatric disorders (e.g., tobacco and alcohol use disorders). Notwithstanding the interest and promise of psychedelics, concerns have arisen with respect to the interpretability and translatability of study results. For example, aspects related to short- and long-term safety, abuse liability, and the essentiality of the psychedelic "trip" and psychological support are, inter alia, insufficiently characterized with psychedelic agents. The overarching aims in this overview are 1) to review methodological aspects that affect inferences and interpretation of extant psychedelic studies in psychiatric disorders, and 2) to provide guidance for future research and development of psychedelic treatment in psychiatry, critical to study interpretation and clinical implementation.

Psilocybin-assisted neurofeedback for the improvement of executive functions: a randomized semi-naturalistic-lab feasibility study

Executive function deficits, common in psychiatric disorders, hinder daily activities and may be linked to diminished neural plasticity, affecting treatment and training responsiveness. In this pioneering study, we evaluated the feasibility and preliminary efficacy of psilocybin-assisted frontal-midline theta neurofeedback (NF), a neuromodulation technique leveraging neuroplasticity, to improve executive functions (EFs). Thirty-seven eligible participants were randomized into an experimental group (n = 18) and a passive control group (n = 19). The experimental group underwent three microdose sessions and then three psilocybin-assisted NF sessions, without requiring psychological support, demonstrating the approach's feasibility. NF learning showed a statistical trend for increases in frontal-midline theta from session to session with a large effect size and non-significant but medium effect size dynamical changes within sessions. Placebo effects were consistent across groups, with no tasks-based EF improvements, but significant self-reported gains in daily EFs-working memory, shifting, monitoring and inhibition-showing medium and high effect sizes. The experimental group's significant gains in their key training goals underscored the approach's external relevance. A thorough study with regular sessions and an active control group is crucial to evaluate EFs improvement and their specificity in future. Psilocybin-enhanced NF could offer significant, lasting benefits across diagnoses, improving daily functioning. This article is part of the theme issue 'Neurofeedback: new territories and neurocognitive mechanisms of endogenous neuromodulation'.

Expectations regarding school decreases emotional distress among college students in Western China: the buffering role of physical exercises

Background

College students in Western China face unique economic, cultural, and educational environments, yet limited studies have specifically investigated the factors or interventions concerning emotional distress within this population.

Aim

This study aimed to explore whether school belongingness mediates the relationship between expectations regarding school and emotional distress among college students in Western China, and whether physical exercise moderates this mediation.

Methods

Employing a cross-sectional design, 1,063 college students in Xinjiang, China were recruited for this study. A self-administered electronic questionnaire assessed expectations regarding school, school belongingness, physical exercise, anxiety, and depression. Structural equation modeling was utilized to analyze mediating and moderating effects.

Results

Expectations regarding school was negatively associated with emotional distress. School exclusion and school acceptance fully mediated the effect of expectations regarding school on emotional distress. Physical exercise moderated the mediating effect of school exclusion, but not that of school acceptance.

Conclusion

Expectations regarding school and school belongingness, particularly the exclusion component, emerge as pivotal factors influencing emotional distress among college students in Western China. Furthermore, physical exercise presents itself as a promising targeted intervention for alleviating emotional distress within this demographic.

Feeling tired versus feeling relaxed: Two faces of low physiological arousal

Human well-being and functioning depend on two fundamental mental states: Relaxation and sleepiness. Relaxation and sleepiness are both assumed to be states of low physiological arousal and negatively correlated. However, it is still unclear how consistent this negative relationship is across different settings and whether it changes before and after an intervention. Here we investigated this intricate relationship between subjective momentary sleepiness and relaxation states by meta-analytically analyzing several data sets from studies using the Relaxation State Questionnaire. We discovered that subjective sleepiness and relaxation were in fact anti-correlated pre-intervention. This anti-correlation provides a quantitative dissociation between sleepiness and relaxation. Thus, even though sleepiness and relaxation both implicate a low arousal level, the two mental states are subjectively experienced in a qualitatively different fashion, and thus reflect distinct underlying constructs. For the post-intervention relationship, this negative correlation could not be consistently found. This indicates that there are aspects of the experimental setting or intervention that introduce changes in the dynamics of the relationship of the two constructs.

LSDDEP2: study protocol for a randomised, double-dummy, triple-blind, active placebo-controlled, parallel groups trial of LSD microdosing in patients with major depressive disorder

BACKGROUND

Major depressive disorder (MDD) poses a significant global health burden with available treatments limited by inconsistent efficacy and notable side effects. Classic psychedelics, including lysergic acid diethylamide (LSD), have garnered attention for their potential in treating psychiatric disorders. Microdosing, the repeated consumption of sub-hallucinogenic doses of psychedelics, has emerged as a self-treatment approach for depression within lay communities. Building upon preliminary evidence and the successful completion of an open-label pilot trial of microdosing LSD for depression (LSDDEP1), this protocol outlines a phase 2b randomised controlled trial (LSDDEP2). The main objective of LSDDEP2 is to assess the modification of depressive symptoms, measured by the Montgomery-Åsberg Depression Rating Scale (MADRS), following a regimen of LSD microdoses versus placebo.

METHODS

This is a randomised, double-dummy, triple-blind, active placebo-controlled, parallel groups trial of LSD microdosing in patients meeting DSM-5 criteria for major depressive disorder. Participants will undergo an 8-week LSD microdosing regimen using the titratable MB-22001 formulation taking two doses a week. All doses will be self-administered at home and will be titratable from 4 to 20 μg based on subjective perception and tolerability. In addition to depression symptoms, outcome will include psychiatric and personality inventories, sleep and activity tracking, electroencephalography (EEG), blood biomarkers, semi-structured interviews, and safety (e.g. adverse event, laboratory exam) measures.

DISCUSSION

This study will be the first randomised controlled trial to administer controlled microdoses of LSD for treatment of MDD in participants' naturalistic environment. The measures included are designed to assess the drug's safety, mechanism, and treatment efficacy over placebo in this population. The results of this study will be important for assessing the viability of psychedelic microdosing as an additional treatment option and for informing the direction of future clinical trials.

TRIAL REGISTRATION

ANZCTR, ACTRN12624000128594. Prospectively Registered on 13 February 2024.

Is microdosing a placebo? A rapid review of low-dose LSD and psilocybin research

Some recent research and commentary have suggested that most or all the effects reported by people who microdose psychedelics may be explained by expectations or placebo effects. In this rapid review, we aimed to evaluate the strength of evidence for a placebo explanation of the reported effects of microdosing. We conducted a PubMed search for all studies investigating psychedelic microdosing with controlled doses and a placebo comparator. We identified 19 placebo-controlled microdosing studies and summarised all positive and null findings across this literature. Risk of bias was assessed using the Cochrane risk-of-bias tool for randomised trials. The reviewed papers indicated that microdosing with LSD and psilocybin leads to changes in neurobiology, physiology, subjective experience, affect, and cognition relative to placebo. We evaluate methodological gaps and challenges in microdosing research and suggest eight reasons why current claims that microdosing is predominately a placebo are premature and possibly wrong: (1) there have been only a small number of controlled studies; (2) studies have had small sample sizes; (3) there is evidence of dose-dependent effects; (4) studies have only investigated the effects of a small number of doses; (5) the doses investigated may have been too small; (6) studies have looked only at non-clinical populations; (7) studies so far have been susceptible to selection bias; and (8) the measured impact of expectancy is small. Considering the available evidence, we conclude that it is not yet possible to determine whether microdosing is a placebo.

Inter-individual variability in neural response to low doses of LSD

The repeated use of small doses of psychedelics (also referred to as "microdosing") to facilitate benefits in mental health, cognition, and mood is a trending practice. Placebo-controlled studies however have largely failed to demonstrate strong benefits, possibly because of large inter-individual response variability. The current study tested the hypothesis that effects of low doses of LSD on arousal, attention and memory depend on an individual's cognitive state at baseline. Healthy participants (N = 53) were randomly assigned to receive repeated doses of LSD (15 mcg) or placebo on 4 occasions divided over 2 weeks. Each treatment condition also consisted of a baseline and a 1-week follow-up visit. Neurophysiological measures of arousal (resting state EEG), pre-attentive processing (auditory oddball task), and perceptual learning and memory (visual long-term potentiation (LTP) paradigm) were assessed at baseline, dosing session 1 and 4, and follow-up. LSD produced stimulatory effects as reflected by a reduction in resting state EEG delta, theta, and alpha power, and enhanced pre-attentive processing during the acute dosing sessions. LSD also blunted the induction of LTP on dosing session 4. Stimulatory effects of LSD were strongest in individuals with low arousal and attention at baseline, while inhibitory effects were strongest in high memory performers at baseline. Decrements in delta EEG power and enhanced pre-attentive processing in the LSD treatment condition were still present during the 1-week follow-up. The current study demonstrates across three cognitive domains, that acute responses to low doses of LSD depend on the baseline state and provides some support for LSD induced neuroadaptations that sustain beyond treatment.

Psychological effects of psychedelics in adolescents

This study aimed to investigate differences in long-term psychological effects, acute subjective effects, and side effects associated with psychedelic use in adolescents (aged 16-24), compared with adults (aged 25+). Data from two observational online survey cohorts was pooled, involving adolescents (average age 20.4 ± 2.2, N = 435) and adults (average age 36.5 ± 9.7, range = 25-71, N = 654) who self-initiated a psychedelic experience and were tracked via online surveys from a pre-experience baseline to four weeks post-use. Self-reported measures of well-being were collected one week before, and two and four weeks after psychedelic use. Acute subjective drug effects, dosage and contextual variables pertaining to the setting of use were measured on the day after the session. Repeated-measures analyses of covariance, t- and z-tests, as well as exploratory correlational and regression analyses tested differences in psychological changes, acute drug effects, and side effects between the two groups. Psychological well-being significantly improved in adolescents two and four weeks following psychedelic use, with a clinically relevant mean change score of 3.3 points (95% CI: 1.1-5.5). on the Warwick-Edinburgh Mental Wellbeing Scale [F(1.8, 172.9) = 13.41, η 2G = .04, p < .001], statistically indistinguishable from changes in adults. Acute subjective effects differed between the age groups; adolescents reported significantly higher challenging experiences and ego-dissolution. In adolescents, visual symptoms related to "hallucinogen persisting perceptual disorder" (HPPD) were reported at a higher prevalence than in adults (73.5% vs. 34.2%, p < .001) but were reported as distressing by only one adolescent participant. To our knowledge, this is the first prospective study to examine the psychological effects of psychedelic use specifically in adolescents. Statistically significant improvements in psychological well-being and other domains of mental health were observed, consistent with effects seen previously in adults, providing tentative evidence for the potential utility of psychedelic interventions in adolescents. However, differences in acute subjective effects, specifically the less positive role of ego-dissolution experiences for long-term changes in adolescents, as well as a higher prevalence of HPPD-related symptoms suggest that special considerations might be required when assessing psychedelic treatment design and risks.

Expectancy Effects in Psychedelic Trials

Clinical trials of psychedelic compounds like psilocybin, lysergic acid diethylamide (LSD), and N,N-dimethyltrptamine (DMT) have forced a reconsideration of how nondrug factors, such as participant expectations, are measured and controlled in mental health research. As doses of these profoundly psychoactive substances increase, so does the difficulty in concealing the treatment condition in the classic double-blind, placebo-controlled trial design. As widespread public enthusiasm for the promise of psychedelic therapy grows, so do questions regarding whether and how much trial results are biased by positive expectancy. First, we review the key concepts related to expectancy and its measurement. Then, we review expectancy effects that have been reported in both micro- and macrodose psychedelic trials from the modern era. Finally, we consider expectancy as a discrete physiological process that can be independent of, or even interact with, the drug effect. Expectancy effects can be harnessed to improve treatment outcomes and can also be actively managed in controlled studies to enhance the rigor and generalizability of future psychedelic trials.

Microdosing Psychedelics: Current Evidence From Controlled Studies

Taking regular low doses of psychedelic drugs (microdosing) is a practice that has drawn recent scientific and media attention for its potential psychotherapeutic effects. Yet, controlled studies evaluating this practice have lagged. Here, we review recent evidence focusing on studies that were conducted with rigorous experimental control. Studies conducted under laboratory settings using double-blind placebo-controlled procedures and investigator-supplied drug were compiled. The review includes demographic characteristics of participants and dependent measures such as physiological, behavioral, and subjective effects of the drugs. Review criteria were met by 14 studies, all of which involved acute or repeated low (5-20 μg) doses of lysergic acid diethylamide (LSD). Acute microdoses of LSD dose-dependently altered blood pressure, sleep, neural connectivity, social cognition, mood, and perception of pain and time. Perceptible drug effects were reported at doses of 10 to 20 μg but not 5 μg. No serious adverse effects were reported. Repeated doses of LSD did not alter mood or cognition on any of the measures studied. The findings suggest that low doses of LSD are safe and produce acute behavioral and neural effects in healthy adults. Further studies are warranted to extend these findings to patient samples and to other psychedelic drugs and to investigate microdosing as a potential pharmacological treatment for psychiatric disorders.

Effects of discontinuation of serotonergic antidepressants prior to psilocybin therapy versus escitalopram for major depression

BACKGROUND

There is growing evidence for the therapeutic effects of the psychedelic drug psilocybin for major depression. However, due to the lack of safety data on combining psilocybin with selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) and concerns that there may be a negative interaction on efficacy, participants enrolling in psychedelic trials are usually required to discontinue SNRI/SNRIs prior to enrolling.

AIMS

Using data from a recent clinical trial examining the comparative efficacy the psychedelic drug psilocybin (P) combined with approximately 20 h of psychological support to a 6-week (daily) course of the SSRI escitalopram plus matched psychological support for major depressive disorder, we explored the effects of discontinuing SSRI/SNRIs prior to study enrolment on study outcomes.

METHODS

Exploratory post hoc analyses using linear mixed effects model were performed to investigate the discontinuation effect on various validated depression symptom severity scales and well-being. The impact of SSRI/SNRIs discontinuation on the acute psychedelic experience was also explored.

RESULTS/OUTCOMES

In the psilocybin group, there was a reduced treatment effect on all outcome measures for SSRI/SNRIs discontinuers compared with unmedicated patients at trial entry. However, no effects of discontinuation on measures of the acute psychedelic experience were found.

CONCLUSION

Discontinuation of SSRI/SNRIs before psilocybin might diminish response to treatment; however, as we did not test SSRI/SNRI continuation in our trial, we cannot infer such causation. Moreover, the exploratory nature of the analyses makes them hypothesis generating, and not confirmatory. A controlled trial of SSRI/SNRI discontinuation versus continuation prior to psilocybin is urgently required.

Unlocking the self: Can microdosing psychedelics make one feel more authentic?

Background and aim: In the present study, we focus on the relationship between state authenticity - the experience of being true to oneself in a particular moment - and microdosing - a practice that implies repeatedly ingesting very small doses of psychedelics that do not reach the threshold for perceptual alterations. We propose that microdosing could increase state authenticity through influencing people's mood and the number and satisfaction with daily activities. Methods: We used self-assessments of state authenticity collected from 18 microdosers in the Netherlands across the period of 1 month for a total of 192 observations. Results: We found that on the microdosing day and the day thereafter, state authenticity was significantly higher. Furthermore, the number of activities and the satisfaction with them were higher on the day when participants microdosed, while the following day only the number of activities was higher. Both the number or activities and the satisfaction with them were positively related to state authenticity. Conclusion: We propose that feeling and behaving authentically could have a central role in explaining the positive effects of microdosing on health and wellbeing that are reported by current research.

Greater subjective effects of a low dose of LSD in participants with depressed mood

Recent studies and anecdotal reports suggest that psychedelics can improve mood states, even at low doses. However, few placebo-controlled studies have examined the acute effects of low doses of LSD in individuals with psychiatric symptoms. In the current study, we examined the acute and sub-acute effect of a low dose of LSD (26 µg) on subjective effects and mood in volunteers with mild depressed mood. The study used a randomized, double-blind, crossover design to compare the effects of LSD in two groups of adults: participants who scored high (≥17; n = 20) or low (<17; n = 19) on the Beck Depression-II inventory (BDI) at screening. Participants received a single low dose of LSD (26 µg) and placebo during two 5-h laboratory sessions, separated by at least one week. Subjective, physiological, and mood measures were assessed at regular intervals throughout the sessions, and behavioral measures of creativity and emotion recognition were obtained at expected peak effect. BDI depression scores and mood ratings were assessed 48-h after each session. Relative to placebo, LSD (26 µg) produced expected, mild physiological and subjective effects on several measures in both groups. However, the high BDI group reported significantly greater drug effects on several indices of acute effects, including ratings of vigor, elation, and affectively positive scales of a measure of psychedelic effects (5D-ASC). The high BDI group also reported a greater decline in BDI depression scores 48-h after LSD, compared to placebo. These findings suggest that an acute low dose of LSD (26 µg) elicits more pronounced positive mood and stimulant-like effects, as well as stronger altered states of consciousness in individuals with depressive symptoms, compared to non-depressed individuals.

Psychedelic Therapy: A Primer for Primary Care Clinicians-Ketamine

BACKGROUND

Ketamine, an arylcyclohexylamine dissociative anesthetic agent, has evolved into a versatile therapeutic. It has a rapid-onset, well-understood cardiovascular effects and a favorable safety profile in clinical use. Its enantiomeric compound, esketamine, was approved by the Food and Drug Administration in 2019 for both treatment-resistant depression and major depressive disorder with suicidal ideation.

AREAS OF UNCERTAINTY

Research indicates dose-dependent impacts on cognition, particularly affecting episodic and working memory following both acute administration and chronic use, albeit temporarily for the former and potentially persistent for the latter. Alongside acute risks to cardiovascular stability, ketamine use poses potential liver toxicity concerns, especially with prolonged or repeated exposure within short time frames. The drug's association with "ketamine cystitis," characterized by bladder inflammation, adds to its profile of physiological risks.

THERAPEUTIC ADVANCES

Data demonstrate a single intravenous infusion of ketamine exhibits antidepressant effects within hours (weighted effect size averages of depression scores (N = 518) following a single 0.5 mg/kg infusion of ketamine is d = 0.96 at 24 hours). Ketamine is also effective at reducing posttraumatic stress disorder (PTSD) symptom severity following repeated infusions (Clinician-Administered PTSD Scale scores: -11.88 points compared with midazolam control). Ketamine also decreased suicidal ideation in emergency settings (Scale for Suicidal Ideation scores: -4.96 compared with midazolam control). Through its opioid-sparing effect, ketamine has revolutionized postoperative pain management by reducing analgesic consumption and enhancing recovery.

LIMITATIONS

Many studies indicate that ketamine's therapeutic effects may subside within weeks. Repeated administrations, given multiple times per week, are often required to sustain decreases in suicidality and depressive symptoms.

CONCLUSIONS

Ketamine's comprehensive clinical profile, combined with its robust effects on depression, suicidal ideation, PTSD, chronic pain, and other psychiatric conditions, positions it as a substantial contender for transformative therapeutic application.

Psychedelics for acquired brain injury: a review of molecular mechanisms and therapeutic potential

Acquired brain injury (ABI), such as traumatic brain injury and stroke, is a leading cause of disability worldwide, resulting in debilitating acute and chronic symptoms, as well as an increased risk of developing neurological and neurodegenerative disorders. These symptoms can stem from various neurophysiological insults, including neuroinflammation, oxidative stress, imbalances in neurotransmission, and impaired neuroplasticity. Despite advancements in medical technology and treatment interventions, managing ABI remains a significant challenge. Emerging evidence suggests that psychedelics may rapidly improve neurobehavioral outcomes in patients with various disorders that share physiological similarities with ABI. However, research specifically focussed on psychedelics for ABI is limited. This narrative literature review explores the neurochemical properties of psychedelics as a therapeutic intervention for ABI, with a focus on serotonin receptors, sigma-1 receptors, and neurotrophic signalling associated with neuroprotection, neuroplasticity, and neuroinflammation. The promotion of neuronal growth, cell survival, and anti-inflammatory properties exhibited by psychedelics strongly supports their potential benefit in managing ABI. Further research and translational efforts are required to elucidate their therapeutic mechanisms of action and to evaluate their effectiveness in treating the acute and chronic phases of ABI.

Microdosing psychedelics and the risk of cardiac fibrosis and valvulopathy: Comparison to known cardiotoxins

Though microdosing psychedelics has become increasingly popular, its long-term effects on cardiac health remain unknown. Microdosing most commonly involves ingesting sub-threshold doses of lysergic acid diethylamide (LSD), psilocybin, or other psychedelic drugs 2-4 times a week for at least several weeks, but potentially months or years. Concerningly, both LSD and psilocybin share structural similarities with medications which raise the risk of cardiac fibrosis and valvulopathy when taken regularly, including methysergide, pergolide, and fenfluramine. 3,4-Methylenedioxymethamphetamine, which is also reportedly used for microdosing, is likewise associated with heart valve damage when taken chronically. In this review, we evaluate the evidence that microdosing LSD, psilocybin, and other psychedelics for several months or more could raise the risk of cardiac fibrosis. We discuss the relationship between drug-induced cardiac fibrosis and the 5-HT2B receptor, and we make recommendations for evaluating the safety of microdosing psychedelics in future studies.

PAM trial protocol: a randomised feasibility study of psychedelic microdosing-assisted meaning-centred psychotherapy in advanced stage cancer patients

BACKGROUND

An advanced cancer diagnosis can be associated with a significant profile of distress. Psychedelic compounds have shown clinically significant effects in the treatment of psychological distress in patients with advanced-stage cancer. Given the challenges of delivering timely and effective intervention in the advanced cancer context, it is possible that an alternative, more pragmatic, approach lies in psychedelic 'microdosing'. Microdosing refers to repeated administration of psychedelics in sub-hallucinogenic doses. The purpose of this study is to evaluate the feasibility of conducting a full-scale randomised controlled trial comparing psychedelic microdose-assisted-meaning-centred psychotherapy (PA-MCP) to standard meaning-centred psychotherapy (MCP) in New Zealand indigenous (Māori) and non-indigenous people with advanced cancer and symptoms of anxiety and/or depression. Although MCP is a well-established psychotherapeutic treatment in advanced cancer populations, the potential efficacy and effectiveness of this therapy when delivered alongside a standardised microdose regimen of a psychedelic compound have not been investigated.

METHODS

Participants with advanced-stage cancer and symptoms of anxiety and/or depression (N = 40; 20 Māori, 20 non-Māori) will be randomised under double-blind conditions to receive 7 sessions of MCP alongside 13 doses of either an LSD microdose (4-20 µg) (PA-MCP) or inactive placebo (placebo-MCP). The feasibility, acceptability, and safety of this intervention and physiological and psychological measures will be recorded at baseline, at each session of MCP, and at a 1-month and 6-month follow-up.

DISCUSSION

Our findings will evaluate the feasibility, acceptability, and safety of a larger randomised controlled trial and provide an initial indication of the potential benefits of psychedelic microdosing for psychological distress in advanced-stage indigenous and non-indigenous cancer patients.

TRIAL REGISTRATION

NZCTR, ACTRN12623000478617. Registered 11 May 2023.  https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=385810&isReview=true .

Psychedelic Microdosing among Young Adults from Southern California

Despite common depictions in the media, there is little scientific evidence on microdosing psychedelic drugs. We assessed awareness, prevalence, and dosing practices of microdosing psychedelic drugs among young adults 18-22 years old from Southern California (2018-2019). We examined whether sociodemographic factors, personality traits, mental health, or other substance use behaviors were correlated with having ever microdosed. Among 2,396 participants, 293 (12%) had heard of microdosing and 74 (3%) ever microdosed. Among those who had heard of microdosing, 79% correctly defined microdosing as taking an amount of a psychedelic much lower than a standard dose, whereas 15% misperceived microdosing as a standard psychedelic dose. Psilocybin was the most common drug ever microdosed (70%), followed by lysergic acid diethylamide (LSD, 57%). Among those who ever microdosed, ~18% reported using psychoactive doses far higher than would be generally considered a microdose. White race, male/masculine gender identity, bisexual identity, past 6-month other drug use, greater attention deficit/hyperactivity disorder symptoms, mindfulness, and sensation-seeking were positively associated with having ever microdosed in multivariable models. Young adult microdosing merits further attention from scientific and public health professionals to help prevent misperceptions and potential adverse consequences as well as explore its potential therapeutic applications.

Keeping the promise: a critique of the current state of microdosing research

Introduction

The practice of taking small, sub-hallucinogenic doses of psychedelics, known as microdosing, has exploded in popularity over the last decade. Users claim benefits ranging from improved mood and enhanced creativity to an increased sense of meaning and connectedness in life. While research on microdosing is still lagging behind the shift in public opinion, several papers have been published in the last five years which attempted to assess the effects of microdosing.

Methods

This review paper aimed to critically analyze the research practices used in the recent wave of microdosing research: We reviewed 15 papers published before the closing date of this review in March 2022.

Results

Our review concludes that it is premature to draw any conclusions about the efficacy or safety of microdosing since the research quality cannot be considered confirmatory.

Discussion

We propose some potential causes for the current state of the literature and some suggestions for how these causes may be ameliorated.

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.

Modulation of long-term potentiation following microdoses of LSD captured by thalamo-cortical modelling in a randomised, controlled trial

BACKGROUND

Microdosing psychedelics is a phenomenon with claimed cognitive benefits that are relatively untested clinically. Pre-clinically, psychedelics have demonstrated enhancing effects on neuroplasticity, which cannot be measured directly in humans, but may be indexed by non-invasive electroencephalography (EEG) paradigms. This study used a visual long-term potentiation (LTP) EEG paradigm to test the effects of microdosed lysergic acid diethylamide (LSD) on neural plasticity, both acutely while on the drug and cumulatively after microdosing every third day for six weeks. Healthy adult males (n = 80) completed the visual LTP paradigm at baseline, 2.5 h following a dose of 10 µg of LSD or inactive placebo, and 6 weeks later after taking 14 repeated microdoses. Visually induced LTP was used as indirect index of neural plasticity. Surface level event-related potential (ERPs) based analyses are presented alongside dynamic causal modelling of the source localised data using a generative thalamocortical model (TCM) of visual cortex to elucidate underlying synaptic circuitry.

RESULTS

Event-related potential (ERP) analyses of N1b and P2 components did not show evidence of changes in visually induced LTP by LSD either acutely or after 6 weeks of regular dosing. However modelling the complete timecourse of the ERP with the TCM demonstrated changes in laminar connectivity in primary visual cortex. This primarily included changes to self-gain and inhibitory input parameters acutely. Layer 2/3 to layer 5 excitatory connectivity was also different between LSD and placebo groups. After regular dosing only excitatory input from layer 2/3 into layer 5 and inhibitory input into layer 4 were different between groups.

CONCLUSIONS

Without modulation of the ERPs it is difficult to relate the findings to other studies visually inducing LTP. It also indicates the classic peak analysis may not be sensitive enough to demonstrate evidence for changes in LTP plasticity in humans at such low doses. The TCM provides a more sensitive approach to assessing changes to plasticity as differences in plasticity mediated laminar connectivity were found between the LSD and placebo groups.

TRIAL REGISTRATION

 ANZCTR registration number ACTRN12621000436875; Registered 16/04/2021 https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=381476 .

Therapeutic mechanisms of psychedelics and entactogens

Recent clinical and preclinical evidence suggests that psychedelics and entactogens may produce both rapid and sustained therapeutic effects across several indications. Currently, there is a disconnect between how these compounds are used in the clinic and how they are studied in preclinical species, which has led to a gap in our mechanistic understanding of how these compounds might positively impact mental health. Human studies have emphasized extra-pharmacological factors that could modulate psychedelic-induced therapeutic responses including set, setting, and integration-factors that are poorly modelled in current animal experiments. In contrast, animal studies have focused on changes in neuronal activation and structural plasticity-outcomes that are challenging to measure in humans. Here, we describe several hypotheses that might explain how psychedelics rescue neuropsychiatric disease symptoms, and we propose ways to bridge the gap between human and rodent studies. Given the diverse pharmacological profiles of psychedelics and entactogens, we suggest that their rapid and sustained therapeutic mechanisms of action might best be described by the collection of circuits that they modulate rather than their actions at any single molecular target. Thus, approaches focusing on selective circuit modulation of behavioral phenotypes might prove more fruitful than target-based methods for identifying novel compounds with rapid and sustained therapeutic effects similar to psychedelics and entactogens.

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.

A journey with psychedelic mushrooms: From historical relevance to biology, cultivation, medicinal uses, biotechnology, and beyond

Psychedelic mushrooms containing psilocybin and related tryptamines have long been used for ethnomycological purposes, but emerging evidence points to the potential therapeutic value of these mushrooms to address modern neurological, psychiatric health, and related disorders. As a result, psilocybin containing mushrooms represent a re-emerging frontier for mycological, biochemical, neuroscience, and pharmacology research. This work presents crucial information related to traditional use of psychedelic mushrooms, as well as research trends and knowledge gaps related to their diversity and distribution, technologies for quantification of tryptamines and other tryptophan-derived metabolites, as well as biosynthetic mechanisms for their production within mushrooms. In addition, we explore the current state of knowledge for how psilocybin and related tryptamines are metabolized in humans and their pharmacological effects, including beneficial and hazardous human health implications. Finally, we describe opportunities and challenges for investigating the production of psychedelic mushrooms and metabolic engineering approaches to alter secondary metabolite profiles using biotechnology integrated with machine learning. Ultimately, this critical review of all aspects related to psychedelic mushrooms represents a roadmap for future research efforts that will pave the way to new applications and refined protocols.

Trait mindfulness and personality characteristics in a microdosing ADHD sample: a naturalistic prospective survey study

Background

Microdosing (MD), repeatedly taking psychedelics in small, non-hallucinogenic amounts, has been practiced by individuals to relieve attention deficit hyperactivity disorder (ADHD) symptoms. Generally, adults diagnosed with ADHD have lower levels of mindfulness and differ in personality structure from non-ADHD adults. How MD affects mindfulness and personality in adults with ADHD remains unexplored.

Aim

This study aimed to investigate the effects of 4 weeks of MD on mindfulness and personality traits in adults diagnosed with ADHD and those experiencing severe ADHD symptoms. It was expected that mindfulness and the personality traits conscientiousness, extraversion, agreeableness, and openness would increase and neuroticism would decrease after 4 weeks of MD compared to baseline. It was explored if using conventional ADHD medication alongside MD and/or having comorbidities influenced MD-induced effects.

Methods

An online prospective naturalistic design was used to measure participants before MD initiation and 2 and 4 weeks later. Validated self-report measures were used assessing mindfulness (15-item Five Facet Mindfulness Questionnaire) and personality traits (10-item version of the Big Five Inventory) at three time points.

Results

The sample included n = 233, n = 66, and n = 44 participants at the three time points, respectively. Trait mindfulness, specifically description and non-judging of inner experience, was increased, and neuroticism was decreased after 4 weeks of MD compared to baseline. The remaining personality traits remained unchanged. Using conventional medication and/or having comorbid diagnoses did not change the MD-induced effects on mindfulness and personality traits after 4 weeks.

Conclusion

MD induced changes in otherwise stable traits. Future placebo-controlled studies are warranted to confirm whether these changes occur in a controlled setting.

An open-label pilot trial assessing tolerability and feasibility of LSD microdosing in patients with major depressive disorder (LSDDEP1)

BACKGROUND

Globally, an estimated 260 million people suffer from depression [1], and there is a clear need for the development of new, alternative antidepressant therapies. In light of problems with the tolerability and efficacy of available treatments [2], a global trend is emerging for patients to self-treat depression with microdoses of psychedelic drugs such as lysergic acid diethylamide (LSD) and psilocybin [3]. Beyond anecdotal reports from those who self-medicate in this way, few clinical trials have evaluated this practice. In our recently published phase 1 study in healthy volunteers [4], we determined that LSD microdosing was relatively safe and well tolerated in that cohort. Furthermore, the data demonstrated that conducting such microdosing trials is broadly feasible, with excellent adherence and compliance to the regimen observed. In this open-label pilot trial of patients with major depressive disorder (LSDDEP1), we will test the tolerability and feasibility of an 8-week regimen of LSD microdosing in this patient group prior to a larger subsequent randomised controlled trial (LSDDEP2).

METHODS

Twenty patients meeting the DSM-5 criteria for major depressive disorder will receive an 8-week LSD microdosing treatment regimen. The treatment protocol will use a sublingual formulation of LSD (MB-22001) delivered twice per week under a titration schedule using a dose of 5-15 µg. Tolerability will be assessed by quantifying the percentage of participants who withdraw from the trial due to adverse events attributable to the treatment regimen, while feasibility will be assessed by quantifying the percentage of attended clinic visits once enrolled. To determine whether there is any antidepressant response to the LSD microdosing regimen, MADRS scores will be assessed at baseline and 2, 4, 6, and 8 weeks after the commencement of the regimen.

DISCUSSION

The results of LSDDEP1 will provide valuable information regarding the tolerability and feasibility of a proposed LSD microdosing regimen in patients with MDD. Such information is critically important to optimise trial design prior to commencing a subsequent and more resource-intensive randomised controlled trial.

TRIAL REGISTRATION

ANZCTR, ACTRN12623000486628. Registered on 12 May 2023.

Acute Mood-Elevating Properties of Microdosed Lysergic Acid Diethylamide in Healthy Volunteers: A Home-Administered Randomized Controlled Trial

BACKGROUND

Microdosing psychedelic drugs is a widespread social phenomenon with diverse benefits claimed for mood and cognition. Randomized controlled trials have failed to support these claims, but the laboratory-based dosing in trials conducted to date may have limited ecological validity.

METHODS

Healthy male volunteers were randomized into lysergic acid diethylamide (LSD) (n = 40) and placebo (n = 40) groups and received 14 doses of either 10 μg LSD or an inactive placebo every 3 days for 6 weeks. First doses were given in a supervised laboratory setting, with other doses self-administered in a naturalistic setting. Results of safety data, blinding, daily questionnaires, expectancy, and pre-/postintervention psychometrics and cognitive tasks are presented here.

RESULTS

The most notable reported adverse event was treatment-related anxiety, which prompted the withdrawal of 4 participants from the LSD group. Daily questionnaires showed credible evidence (>99% posterior probability) of improved ratings of creativity, connectedness, energy, happiness, irritability, and wellness on dose days compared with nondose days, and these effects remained when controlling for preintervention expectancy. No questionnaire or cognitive task showed a credible change between baseline and 6-week assessment time points.

CONCLUSIONS

Microdosing LSD appears to be relatively safe in healthy adult men, notwithstanding a risk of anxiety. While microdosing elicited transient increases in scales associated with mood-elevating effects, it was not sufficient to promote enduring changes to overall mood or cognition in healthy adults. Future microdosing trials in clinical populations will require the use of active placebos to control for placebo effects and dose titration to adjust for interindividual variability in drug response.

The risk of chronic psychedelic and MDMA microdosing for valvular heart disease

Psychedelic microdosing is the practice of taking very low doses of psychedelic substances, typically over a longer period of time. The long-term safety of chronic microdosing is relatively uncharacterized, but valvular heart disease (VHD) has been proposed as a potential risk due to activation of the serotonin 5-HT2B receptor. However, this risk has not yet been comprehensively assessed. This analysis searched for all relevant in vitro, animal, and clinical studies related to the VHD risk of lysergic acid diethylamide (LSD), psilocybin, mescaline, N,N-dimethyltryptamine (DMT), and the non-psychedelic 3,4-methylenedioxymethamphetamine (MDMA). All five compounds and some metabolites could bind to the 5-HT2B receptor with potency equal to or greater than that of the 5-HT2A receptor, the primary target of psychedelics. All compounds were partial agonists at the 5-HT2B receptor with the exception of mescaline, which could not be adequately assessed due to low potency. Safety margins relative to the maximum plasma concentrations from typical microdoses were greater than known valvulopathogens, but not without potential risk. No animal or clinical studies appropriately designed to evaluate VHD risk were found for the four psychedelics. However, there is some clinical evidence that chronic ingestion of full doses of MDMA is associated with VHD. We conclude that VHD is a potential risk with chronic psychedelic microdosing, but further studies are necessary to better define this risk.

Repeated low doses of psilocybin increase resilience to stress, lower compulsive actions, and strengthen cortical connections to the paraventricular thalamic nucleus in rats

Psilocybin (a classic serotonergic psychedelic drug) has received appraisal for use in psychedelic-assisted therapy of several psychiatric disorders. A less explored topic concerns the use of repeated low doses of psychedelics, at a dose that is well below the psychedelic dose used in psychedelic-assisted therapy and often referred to as microdosing. Psilocybin microdose users frequently report increases in mental health, yet such reports are often highly biased and vulnerable to placebo effects. Here we establish and validate a psilocybin microdose-like regimen in rats with repeated low doses of psilocybin administration at a dose derived from occupancy at rat brain 5-HT2A receptors in vivo. The rats tolerated the repeated low doses of psilocybin well and did not manifest signs of anhedonia, anxiety, or altered locomotor activity. There were no deficits in pre-pulse inhibition of the startle reflex, nor did the treatment downregulate or desensitize the 5-HT2A receptors. However, the repeated low doses of psilocybin imparted resilience against the stress of multiple subcutaneous injections, and reduced the frequency of self-grooming, a proxy for human compulsive actions, while also increasing 5-HT7 receptor expression and synaptic density in the paraventricular nucleus of the thalamus. These results establish a well-validated regimen for further experiments probing the effects of repeated low doses of psilocybin. Results further substantiate anecdotal reports of the benefits of psilocybin microdosing as a therapeutic intervention, while pointing to a possible physiological mechanism.

Psilocybin history, action and reaction: A narrative clinical review

Hallucinogenic mushrooms have been used in religious and cultural ceremonies for centuries. Of late, psilocybin, the psychoactive compound in hallucinogenic mushrooms, has received increased public interest as a novel drug for treating mood and substance use disorders (SUDs). In addition, in recent years, some states in the United States have legalized psilocybin for medical and recreational use. Given this, clinicians need to understand the potential benefits and risks related to using psilocybin for therapeutic purposes so that they can accurately advise patients. This expert narrative review summarizes the scientific basis and clinical evidence on the safety and efficacy of psilocybin-assisted therapy for treating psychiatric disorders and SUDs. The results of this review are structured as a more extensive discussion about psilocybin's history, putative mechanisms of action, and recent legislative changes to its legal status. There is modest evidence of psilocybin-assisted therapy for treating depression and anxiety disorders. In addition, early data suggest that psilocybin-assisted therapy may effectively reduce harmful drinking in patients with alcohol use disorders. The evidence further suggests psilocybin, when administered under supervision (psilocybin-assisted therapy), the side effects experienced are mild and transient. The occurrence of severe adverse events following psilocybin administration is uncommon. Still, a recent clinical trial found that individuals in the psilocybin arm had increased suicidal ideations and non-suicidal self-injurious behaviors. Given this, further investigation into the safety and efficacy of psilocybin-assisted therapy is warranted to determine which patient subgroups are most likely to benefit and which are most likely to experience adverse outcomes related to its use.

The difference between 'placebo group' and 'placebo control': a case study in psychedelic microdosing

In medical trials, 'blinding' ensures the equal distribution of expectancy effects between treatment arms in theory; however, blinding often fails in practice. We use computational modelling to show how weak blinding, combined with positive treatment expectancy, can lead to an uneven distribution of expectancy effects. We call this 'activated expectancy bias' (AEB) and show that AEB can inflate estimates of treatment effects and create false positive findings. To counteract AEB, we introduce the Correct Guess Rate Curve (CGRC), a statistical tool that can estimate the outcome of a perfectly blinded trial based on data from an imperfectly blinded trial. To demonstrate the impact of AEB and the utility of the CGRC on empirical data, we re-analyzed the 'self-blinding psychedelic microdose trial' dataset. Results suggest that observed placebo-microdose differences are susceptible to AEB and are at risk of being false positive findings, hence, we argue that microdosing can be understood as active placebo. These results highlight the important difference between 'trials with a placebo-control group', i.e., when a placebo control group is formally present, and 'placebo-controlled trials', where patients are genuinely blind. We also present a new blinding integrity assessment tool that is compatible with CGRC and recommend its adoption.

Associations between the use of psychedelics and other recreational drugs with mental health and resilience during the COVID-19 pandemic

The large-scale disruption to peoples' daily lives during the COVID-19 pandemic provides a context for examining whether use of substances such as psychedelics in a naturalistic (outside of a controlled environment) setting, is associated with better mental wellbeing and resilience relative to those who use other drugs, or who do not use drugs at all. We interrogate data from the Great British Intelligence Test and identify that 7.8% out of N = 30,598 unique respondents used recreational drugs inclusive of psychedelics, cannabis, cocaine, and MDMA during the COVID-19 pandemic. Recruitment materials did not mention drug use would be surveyed, thereby enabling us to model the relationship with mood and resilience in people who had not specifically self-selected themselves for a 'drug' study. We report that people form clusters, characterized by different real-world patterns of drug use, and the majority of psychedelics users also use cannabis. However, a subset of cannabis users do not use psychedelics, enabling a subtractive comparison. Those who primarily used psychedelics and cannabis during the COVID-19 pandemic had worse mood self-assessment and resilience scores compared to those who never used drugs or primarily used cannabis. This pattern was also evident for other recreational drug use clusters, except for those who primarily used MDMA and cannabis, who had better mood but were of too low incidence to have confidence in this estimate. These findings cast light on the significant differences in mental wellbeing between users of different drugs and the non-user population during a global-crisis and call for future research to explore the pharmacological, contextual and cultural variables associated with these differences, their generalisability and causal links with greater precision.

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.

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.

Experiences of microdosing psychedelics in an attempt to support wellbeing and mental health

BACKGROUND

Microdosing psychedelic drugs is a growing phenomenon, but little is known about the experiences surrounding this. Research broadly suggests that people may use psychedelics in an attempt to self-medicate for mental health and wellbeing. However, the precise details, rationale and meaning of such attempts remains unclear, and would benefit from clarification, using tailored experiential methods. This research therefore aimed to explore the way that users make sense of microdosing psychedelics, with a particular focus on the experience of any perceived mental health or wellbeing changes.

METHOD

Participants were recruited via websites and online forums. An internet text-based, semi-structured interview was conducted anonymously with 13 participants regarding their experiences of microdosing psychedelic drugs. Interpretive Phenomenological Analysis was used to analyse the transcripts.

RESULTS

Three superordinate themes were identified through the interviews: 1) Seeking a solution: Agency and rationale; 2) Microdosers as scientists; 3) Catalysing desirable and beneficial effects.

CONCLUSIONS

All participants approached microdosing methodically and with purpose. Participants reported that they had experienced beneficial effects of microdosing on their mental health, alongside cognitive, physical and social changes. By microdosing, participants reported that they had supported their own mental health and wellbeing, with microdosing described as a catalyst to achieving their aims in this area. This study provided additional knowledge and understanding of the experience, rationale and personal meaning of the microdosing phenomenon which can be used to inform future investigations in the areas of psychedelic use and mental health.

Psilocybin mitigates the cognitive deficits observed in a rat model of Fragile X syndrome

RATIONALE

Fragile X syndrome (FXS) is the most common form of inherited intellectual disability (ID) and the leading monogenic cause of autism spectrum disorder (ASD). Serotonergic neurotransmission has a key role in the modulation of neuronal activity during development, and therefore, it has been hypothesized to be involved in ASD and co-occurring conditions including FXS. As serotonin is involved in synaptic remodeling and maturation, serotonergic insufficiency during childhood may have a compounding effect on brain patterning in neurodevelopmental disorders, manifesting as behavioral and emotional symptoms. Thus, compounds that stimulate serotonergic signaling such as psilocybin may offer promise as effective early interventions for developmental disorders such as ASD and FXS.

OBJECTIVES

The aim of the present study was to test whether different protocols of psilocybin administration mitigate cognitive deficits displayed by the recently validated Fmr1-^Δexon 8 rat model of ASD, which is also a model of FXS.

RESULTS

Our results revealed that systemic and oral administration of psilocybin microdoses normalizes the aberrant cognitive performance displayed by adolescent Fmr1-^Δexon 8 rats in the short-term version of the novel object recognition test-a measure of exploratory behavior, perception, and recognition.

CONCLUSIONS

These data support the hypothesis that serotonin-modulating drugs such as psilocybin may be useful to ameliorate ASD-related cognitive deficits. Overall, this study provides evidence of the beneficial effects of different schedules of psilocybin treatment in mitigating the short-term cognitive deficit observed in a rat model of FXS.

Therapeutic effect of psilocybin in addiction: A systematic review

BACKGROUND

Psychedelic-assisted therapy [e.g., with lysergic acid diethylamide (LSD)] has shown promising results as treatment for substance use disorders (SUDs). Previous systematic reviews assessing the efficacy of psilocybin in SUDs only included clinical trials conducted in the last 25 years, but they may have missed clinical trials assessing the efficacy of psilocybin that were conducted before the 1980s, given much research has been done with psychedelics in the mid-20th century. In this systematic review, we specifically assessed the efficacy of psilocybin in patients with a SUD or non-substance-related disorder with no publication date restrictions in our search strategy.

METHODS

A systematic literature search was performed according to Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) guidelines from the earliest published manuscript up to September 2, 2022, in seven electronic databases, including clinical trials in patients with a SUD or non-substance-related disorder evaluating the efficacy of psilocybin.

RESULTS

A total of four studies (six articles, of which two articles were long-term follow-up results from the same trial) were included in this systematic review. Psilocybin-assisted therapy was administered to n = 151 patients in a dose ranging from 6 to 40 mg. Three studies focused on alcohol use disorder, and one study on tobacco use disorder. In a pilot study (n = 10), the percentage of heavy drinking days decreased significantly between baseline and weeks 5-12 (mean difference of 26.0, 95% CI = 8.7-43.2, p = 0.008). In another single-arm study (n = 31), 32% (10/31) became completely abstinent from alcohol (mean duration of follow-up 6 years). In a double-blind, placebo-controlled randomized controlled trial (RCT, n = 95), the percentage of heavy drinking days during the 32-week double-blind period was significantly lower for psilocybin compared to placebo (mean difference of 13.9, 95% CI = 3.0-24.7, p = 0.01). In a pilot study (n = 15), the 7-day point prevalence of smoking abstinence at 26 weeks was 80% (12/15), and at 52 weeks 67% (10/15).

CONCLUSION

Only one RCT and three small clinical trials were identified assessing the efficacy of psilocybin combined with some form of psychotherapy in patients with alcohol and tobacco use disorder. All four clinical trials indicated a beneficial effect of psilocybin-assisted therapy on SUD symptoms. Larger RCTs in patients with SUDs need to evaluate whether psilocybin-assisted therapy is effective in patients with SUD.

Among psychedelic-experienced users, only past use of psilocybin reliably predicts nature relatedness

BACKGROUND

Past research reports a positive relationship between experience with classic serotonergic psychedelics and nature relatedness (NR). However, these studies typically do not distinguish between different psychedelic compounds, which have a unique psychopharmacology and may be used in specific contexts and with different intentions. Likewise, it is not clear whether these findings can be attributed to substance use per se or unrelated variables that differentiate psychedelic users from nonusers.

AIMS

The present study was designed to determine the relative degree to which lifetime experience with different psychedelic substances is predictive of self-reported NR among psychedelic-experienced users.

METHODS

We conducted a combined reanalysis of five independent datasets (N = 3817). Using standard and regularized regression analyses, we tested the relationship between degree of experience with various psychedelic substances (binary and continuous) and NR, both within a subsample of psychedelic-experienced participants as well as the complete sample including psychedelic-naïve participants.

RESULTS/OUTCOMES

Among people experienced with psychedelics, only past use of psilocybin (versus LSD, mescaline, Salvia divinorum, ketamine, and ibogaine) was a reliable predictor of NR and its subdimensions. Weaker, less reliable results were obtained for the pharmacologically similar N,N-dimethyltryptamine (DMT). Results replicate when including psychedelic-naïve participants. In addition, among people exclusively experience with psilocybin, use frequency positively predicted NR.

CONCLUSIONS/INTERPRETATION

Results suggest that experience with psilocybin is the only reliable (and strongest) predictor of NR. Future research should focus on psilocybin when investigating effects of psychedelic on NR and determine whether pharmacological attributes or differences in user expectations/use settings are responsible for this observation.

Set and setting in microdosing: an oft-overlooked principle

RATIONALE

The use of psychedelics for medical and recreational purposes is rising. Contextual factors such as expectancy, intention, and sensory and social environment (set and setting) are widely recognized as moderating the effects of these substances. Nevertheless, clinical trials of microdosing - the ingestion of small, sub-hallucinogenic doses of psychedelics - rarely report their set and setting. This fact suggests that such factors are not considered important in the context of microdosing.

OBJECTIVE

This paper challenges this assumption and makes the case for the crucial relevance of set and setting in microdosing practice. Building on set and setting theory and placebo theory, we explain why set and setting are of crucial importance in the case of microdosing.

RESULTS

This reasoning helps elucidate the role of set and setting in determining the outcomes of microdosing and helps explain some of the contradictory results that have emerged in microdosing research in recent years.

CONCLUSION

Set and setting are important constructs to be considered especially in the context of microdosing psychedelics. By reporting set and setting, the results of microdosing research can be made more reliable and consistent.

Analgesic potential of macrodoses and microdoses of classical psychedelics in chronic pain sufferers: a population survey

Although several studies and reports have shown the potential analgesic use of serotonergic psychedelics in cancer pain, phantom limb pain and cluster headache, evidence supporting their use for chronic pain is still limited. The past years have seen a considerable renewal of interest toward the therapeutic use of these compounds for mood disorders, resulting in a marked increase in the number of people turning to psychedelics in an attempt to self-medicate a health condition or improve their wellbeing. In western countries particularly, this population of users overlaps substantially with chronic pain sufferers, representing a unique opportunity to evaluate the effects these compounds have on pain and wellbeing. Here, we report results from an online survey conducted between August 2020 and July 2021 in a population of 250 chronic pain sufferers who had experience with psychedelics, either in microdoses (small sub-hallucinogenic doses), macrodoses (hallucinogenic doses), or both. Macrodoses, while less often used for analgesic purposes than microdoses, were reported to induce a higher level of pain relief than both microdoses and conventional pain medications (including opioids and cannabis). Although the effects were weaker and potentially more prone to expectation bias than with macrodoses, our results also suggested some benefits of psychedelics in microdoses for pain management. The reported analgesic effect appeared unrelated to mood improvements associated with psychedelic use, or the advocacy of psychedelic use. Taken together, our findings indicate interesting potential analgesic applications for psychedelics that warrant further clinical research.

Modalities of the psychedelic experience: Microclimates of set and setting in hallucinogen research and culture

Mid-20th-century American research on psychedelics evinced a stunning diversity of interpretations of hallucinogenic effects. While some researchers viewed psychedelics as invaluable tools for psychotherapy, others persisted in treating them as psychosis-inducing agents. As some groups considered psychedelics as catalysts for artistic creativity, others investigated their potential use as psychochemical weapons in the battlefield, or conversely as tools for spiritual ecstasy and revelation. This bewildering array of perceptions regarding the nature of hallucinogenic effects led to stark contrasts in the contexts (set and setting) of psychedelic research and experimentation, leading to wildly divergent outcomes and reports on the effects of the drugs, and strident disagreements between the actors in the field. Examining this remarkable historical moment of epistemological unclarity regarding psychedelics and their effects, this article describes how distinct scientific and cultural trends and moments of mid-20th-century America contributed to the creation of diverse microclimates of set and setting that reproduced investigator beliefs and attitudes and brought about a beguiling Pygmalion effect that left researchers befuddled and perplexed. I propose the concept of psychedelic modality to describe how distinct sociocultural microclimates lead to thematic aggregates in which distinct types of expectations, intentions as well as physical, social, and cultural environments all tend to cluster, producing characteristic outcomes and results. By exploring the historical context and consequences of the emergence of seven psychedelic modalities (psychotomimetic, military, psychotherapeutic, spiritual, artistic-creative, tech-innovative, and political) in mid-20th-century America, this article outlines the varieties of psychedelic experiences in their relationship with culture at large, and subcultures in particular.