Psychedelics

Psilocybin in pharmacotherapy of obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a chronic mental disease that affects approximately 2% of the population. Obsessions and compulsions are troublesome for patients and may disturb their everyday activities. The pathogenesis of this disease is still not fully elucidated, but dysfunctions of serotonin-, dopamine- and glutamate-mediated neurotransmission together with early maladaptive schemas seem of importance. Pharmacological treatment includes drugs affecting the serotoninergic, dopaminergic, and glutamatergic systems, such as selective serotonin reuptake inhibitors (SSRIs). Providing that up to 40% of patients with OCD are resistant to the currently available medications, there is a need for novel and effective therapies. Recent discoveries suggest that psilocybin, a non-physically addictive psychoactive substance, may ameliorate disease symptoms. When used in appropriate doses and under strict clinical control, psilocybin appears as a valuable treatment for OCD. This narrative article provides a thorough overview of OCD's etiology, current treatment options, and the emerging evidence supporting psilocybin's efficacy in managing OCD symptoms.

Attitudes toward psychedelics and psychedelic-assisted therapy among potential mental health service users and the general population in Australia

OBJECTIVE

Despite rapid advances in psychedelic sciences and the increasing number of countries legalizing psychedelics for the treatment of mental illnesses, the attitudes, knowledge and readiness of both mental health consumers and the general population remain largely unknown.

METHODS

A cross-sectional survey was conducted among Australians, targeting individuals with mental illness as potential mental health service users. A sub-sample of individuals free of mental illness was also surveyed to assess attitudes in the general population. Participants completed the Attitudes on Psychedelics Questionnaire, the Basic Knowledge of Psychedelics Test and a questionnaire by Corrigan et al. to capture attitudes toward psychedelic therapy by mental health service users.

RESULTS

Of the 502 respondents, 64.5% self-identified as having a mental illness. A significant proportion favored legalizing psychedelics for medical use (43%) and were open to their use (52.4%), yet fewer viewed their effects positively (24%) or considered them safe (33%). Most participants reported to be psychedelic naive (61%). Participants with mental illness had significantly more experience with psychedelics than participant free of mental illness (44.1% vs 29.7%). Experience, perceived knowledge and actual knowledge significantly predicted attitudes toward legalization, effects, risks and openness to psychedelics.

CONCLUSIONS

While a large proportion of Australians are in favor of legalizing psychedelics for medical purposes, concerns about safety remain. People with self-identified mental illness, those with previous recreational psychedelic experience and those with greater knowledge of psychedelics were more likely to have positive attitudes toward psychedelics and psychedelic-assisted therapy.

Decoupling of cortical activity from behavioral state following administration of the classic psychedelic DOI

Administration or consumption of classic psychedelics (CPs) leads to profound changes in experience which are often described as highly novel and meaningful. They have shown substantial promise in treating depressive symptoms and may be therapeutic in other situations. Although research suggests that the therapeutic response is correlated with the intensity of the experience, the neural circuit basis for the alterations in experience caused by CPs requires further study. The medial prefrontal cortex (mPFC), where CPs have been shown to induce rapid, 5-HT2A receptor-dependent structural and neurophysiological changes, is believed to be a key site of action. To investigate the acute neural circuit changes induced by CPs, we recorded single neurons and local field potentials in the mPFC of freely behaving male mice after administration of the 5-HT2A/2C receptor-selective CP, 2,5-Dimethoxy-4-iodoamphetamine (DOI). We segregated recordings into active and rest periods in order to examine cortical activity during desynchronized (active) and synchronized (rest) states. We found that DOI induced a robust decrease in low frequency power when animals were at rest, attenuating the usual synchronization that occurs during less active behavioral states. DOI also increased broadband gamma power and suppressed activity in fast-spiking neurons in both active and rest periods. Together, these results suggest that the CP DOI induces persistent desynchronization in mPFC, including during rest when mPFC typically exhibits more synchronized activity. This shift in cortical dynamics may in part underlie the longer-lasting effects of CPs on plasticity, and may be critical to their therapeutic properties.

Current Perspectives on the Clinical Research and Medicalization of Psychedelic Drugs for Addiction Treatments: Safety, Efficacy, Limitations and Challenges

Mental health disorders and substance use disorders (SUDs) in particular, contribute greatly to the global burden of disease. Psychedelics, including entactogens and dissociative substances, are currently being explored for the treatment of SUDs, yet with less empirical clinical evidence than for other mental health disorders, such as depression or post-traumatic stress disorder (PTSD). In this narrative review, we discuss the current clinical research evidence, therapeutic potential and safety of psilocybin, lysergic acid diethylamide (LSD), ketamine, 3,4-methylenedioxymethamphetamine (MDMA) and ibogaine, particularly in the context of the SUD treatment. Our aim was to provide a balanced overview of the current research and findings on potential benefits and harms of psychedelics in clinical settings for SUD treatment. We highlight the need for more clinical research in this particular treatment area and point out some limitations and challenges to be addressed in future research.

Enhancing translation: A need to leverage complex preclinical models of addictive drugs to accelerate substance use treatment options

Preclinical models of addictive drugs have been developed for decades to model aspects of the clinical experience in substance use disorders (SUDs). These include passive exposure as well as volitional intake models across addictive drugs and have been utilized to also measure withdrawal symptomatology and potential neurobehavioral mechanisms underlying relapse to drug seeking or taking. There are a number of Food and Drug Administration (FDA)-approved medications for SUDs, however, many demonstrate low clinical efficacy as well as potential sex differences, and we also note gaps in the continuum of care for certain aspects of clinical experiences in individuals who use drugs. In this review, we provide a comprehensive update on both frequently utilized and novel behavioral models of addiction with a focus on translational value to the clinical experience and highlight the need for preclinical research to follow epidemiological trends in drug use patterns to stay abreast of clinical treatment needs. We then note areas in which models could be improved to enhance the medications development pipeline through efforts to enhance translation of preclinical models. Next, we describe neuroscience efforts that can be leveraged to identify novel biological mechanisms to enhance medications development efforts for SUDs, focusing specifically on advances in brain transcriptomics approaches that can provide comprehensive screening and identification of novel targets. Together, the confluence of this review demonstrates the need for careful selection of behavioral models and methodological parameters that better approximate the clinical experience combined with cutting edge neuroscience techniques to advance the medications development pipeline for SUDs.

Whole brain modelling for simulating pharmacological interventions on patients with disorders of consciousness

Disorders of consciousness (DoC) represent a challenging and complex group of neurological conditions characterised by profound disturbances in consciousness. The current range of treatments for DoC is limited. This has sparked growing interest in developing new treatments, including the use of psychedelic drugs. Nevertheless, clinical investigations and the mechanisms behind them are methodologically and ethically constrained. To tackle these limitations, we combined biologically plausible whole-brain models with deep learning techniques to characterise the low-dimensional space of DoC patients. We investigated the effects of model pharmacological interventions by including the whole-brain dynamical consequences of the enhanced neuromodulatory level of different neurotransmitters, and providing geometrical interpretation in the low-dimensional space. Our findings show that serotonergic and opioid receptors effectively shifted the DoC models towards a dynamical behaviour associated with a healthier state, and that these improvements correlated with the mean density of the activated receptors throughout the brain. These findings mark an important step towards the development of treatments not only for DoC but also for a broader spectrum of brain diseases. Our method offers a promising avenue for exploring the therapeutic potential of pharmacological interventions within the ethical and methodological confines of clinical research.

Ventral hippocampal parvalbumin interneurons gate the acute anxiolytic action of the serotonergic psychedelic DOI

There has been a recent renewal of interest in the therapeutic potential of serotonergic psychedelics. Here, we uncover the essential role of ventral hippocampus (vHpc) GABAergic interneurons in the anxiolytic effect evoked by the serotonergic psychedelic 2,5-dimethoxy-4-iodoamphetamine (DOI). Integrating anatomical, pharmacological, and genetic approaches, we show that 5-HT2A receptors in the CA1/subiculum (CA1/sub) region of the vHpc are required for the anxiolytic action of DOI. In vivo electrophysiology and opto-tagging experiments indicate that DOI enhances the firing rate of hippocampal fast-spiking parvalbumin (PV)-positive interneurons, most of which express the 5-HT2A receptors. Restoration of 5-HT2A receptors in PV-positive interneurons in a loss-of-function background reinstated the anxiolytic responses evoked by DOI in the vHpc CA1/sub region. Collectively, our results localize the acute anxiolytic action of a serotonergic psychedelic to 5-HT2A receptors in the ventral hippocampus and specifically identify PV-positive fast-spiking cells as a cellular trigger for the psychedelic-induced relief of anxiety-like behavior.

Rethinking the role of TRKB in the action of antidepressants and psychedelics

Antidepressant drugs promote neuronal plasticity, and activation of brain-derived neurotrophic factor (BDNF) signaling through its receptor neuronal receptor tyrosine kinase 2 (NTRK2 or TRKB) is among the critical steps in this process. These mechanisms are shared by typical slow-acting antidepressants, fast-acting ketamine, and psychedelic compounds, although the cellular targets of each drug differ. In this opinion, we propose that some of these antidepressants may directly bind to TRKB and allosterically potentiate BDNF signaling, among other possible effects. TRKB activation in parvalbumin-containing interneurons disinhibits cortical networks and reactivates a juvenile-like plasticity window. Subsequent rewiring of aberrant networks, coupled with environmental stimuli, may underlie its clinical antidepressant effects. The end-to-end hypothesis proposed may stimulate the search for new treatment strategies.

Psychedelics: A review of their effects on recalled aversive memories and fear/anxiety expression in rodents

Threatening events and stressful experiences can lead to maladaptive memories and related behaviors. Existing treatments often fail to address these issues linked to anxiety/stress-related disorders effectively. This review identifies dose ranges associated with specific actions across various psychedelics. We examined psilocybin/psilocin, lysergic acid diethylamide (LSD), N,N-dimethyltryptamine (DMT), mescaline, 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT), serotonin 2 A/2 C agonists (e.g., DOI) and 3,4-methylenedioxymethamphetamine (MDMA) on aversive memory extinction and reconsolidation, learned fear, anxiety, and locomotion in rodents. Nearly 400 studies published since 1957 were reviewed. Psychedelics often show biphasic effects on locomotion at doses that enhance extinction learning/retention, impair memory reconsolidation, or reduce learned fear and anxiety. Emerging evidence suggests a dissociation between their prospective benefits and locomotor effects. Under-explored aspects include sex differences, susceptibility to interference as memories age and generalize, repeated treatments, and immediate vs. delayed changes. Validating findings in traumatic-like memory and maladaptive fear/anxiety models is essential. Understanding how psychedelics modulate threat responses and post-retrieval memory processes in rodents may inform drug development and human studies, improving therapeutic approaches for related psychiatric conditions.

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.

Claustrum and dorsal endopiriform cortex complex cell-identity is determined by Nurr1 and regulates hallucinogenic-like states in mice

The Claustrum/dorsal endopiriform cortex complex (CLA) is an enigmatic brain region with extensive glutamatergic projections to multiple cortical areas. The transcription factor Nurr1 is highly expressed in the CLA, but its role in this region is not understood. By using conditional gene-targeted mice, we show that Nurr1 is a crucial regulator of CLA neuron identity. Although CLA neurons remain intact in the absence of Nurr1, the distinctive gene expression pattern in the CLA is abolished. CLA has been hypothesized to control hallucinations, but little is known of how the CLA responds to hallucinogens. After the deletion of Nurr1 in the CLA, both hallucinogen receptor expression and signaling are lost. Furthermore, functional ultrasound and Neuropixel electrophysiological recordings revealed that the hallucinogenic-receptor agonists' effects on functional connectivity between prefrontal and sensorimotor cortices are altered in Nurr1-ablated mice. Our findings suggest that Nurr1-targeted strategies provide additional avenues for functional studies of the CLA.

Single-dose 1cp-LSD administration for canine anxiety: a pilot study

Anxiety affects 14-20% of dogs. Pharmacological treatments often fail. Psychedelics have shown to be useful for anxiety and depression in humans, but their veterinary use remains unexplored. We aimed to determine the effects of low-dose 1-cyclopropionyl-d-lysergic acid diethylamide (1cp-LSD) administered in a single dose to a dog, to observe the effect and establish the safety of the substance. The patient was a 13-year-old female dog, weighing 13 kg, mixed breed, and spayed. A total of 5 µg was administered orally, equivalent to 0.38 µg/kg. The animal has had a history of separation related behavioral problems throughout her life. To objectively assess the degree of anxiety in the dog, a validated scale was utilized. The trial was scheduled at the house where the animal lives. The owner was present throughout the experience. Informed consent was obtained prior to the assay. The trial began at 12:15 p.m. on January 10, 2024, lasting for 5 and a half hours. The response to anxiety-inducing stimuli was equally anxious during the first two hours. From that point onwards, a significant change in the animal's behavior was observed, with no signs/mild signs of anxiety. The trial concluded without any adverse effects on the animal. The patient did not show signs of having a psychedelic experience. This is the first time that a study of this nature has been conducted and reported in the canine species. 1cp-LSD proved to be safe and exerted the desired effect on the animal's behavior, significantly reducing the patient's anxiety.

Psychedelics as a potential treatment for tobacco use disorder: a systematic review

INTRODUCTION

Despite considerable efforts, tobacco use disorder persists as a significant public health issue. The effectiveness of current smoking cessation therapies is limited, leading to a growing interest in alternative treatment approaches such as psychedelics.

AIM

The aim of this review is to evaluate the scientific evidence regarding the role of psychedelics in smoking cessation.

METHODS

To identify relevant literature on psychedelics and smoking cessation, a search was conducted in four academic literature databases PubMed, MEDLINE, PsycINFO, and Embase. Databases were searched from their inception up to March 24, 2024.

RESULTS

Out of the 1073 articles identified in databases, 8 publications (both clinical and non-clinical studies) met the inclusion criteria, of which a total of 4 publications originated from a single study. The majority of the studies focused on psilocybin (n = 7), for which supportive evidence was suggested for the treatment of tobacco use disorder. Additionally, research was conducted with other psychedelics for smoking cessation, such as ayahuasca, mescaline, peyote, lysergic acid diethylamide (LSD), lysergic acid amide (LSA) and (dimethyltryptamine (DMT), but the evidence base for these psychedelics is too small to draw definitive conclusions.

CONCLUSIONS

There is, although limited, evidence that psychedelics, in particular psilocybin, may offer a potential avenue for combating tobacco use disorder, though more research is needed to understand their effectiveness and safety fully.

A bibliometric analysis of research on psychedelics for depression treatment

Psychedelics, as a class of potent psychoactive substances, significantly alter sensory perception and mood, thereby profoundly impacting cognition. Increasing evidence indicates that psychedelics can facilitate individual social function and rapidly and sustainably improve symptoms of moderate and severe depression. The growing interest in psychedelics as potential treatments for depression has led to a substantial increase in related publications; however, the overall quantity and quality of these works remain unclear. To address this issue, we conducted a bibliometric analysis of literature on psychedelic drugs for depression published between 2004 and October 2023. Our study meticulously collected 710 publications, allowing for a comprehensive analysis of bibliographic elements such as annual publication trends, authorship, country of origin, institutional affiliations, journals, and keywords. By visualizing trends, emerging frontiers, popular topics, author collaborations, and influential factors in the field of psychedelics for depression, we have enhanced our understanding of advancements in this area. On this basis, we assert that the regulation of psychedelic drugs is necessary, but it should not hinder the scientific research progress.

Chiral Switches of Tramadol Hydrochloride, a Potential Psychedelic Drug-Past and Future

The chiral opioid analgesic tramadol was patented (1962) as a cis- and trans-racemates mixture. A first chiral switch led to the (±)-cis-(1RS,2RS) racemate, patented and approved as Tramal (1980), preferred over the (+)-cis-(1R,2R)-enantiomer. Consecutive chiral switches of (±)-cis-tramadol to (+)-cis-(1R,2R)-tramadol/salts were patented. This Viewpoint calls for developing (+)-cis-(1R,2R)-tramadol medicines and recognizing tramadol medicines as potential psychedelics to overcome the spreading tramadol crisis.

Psychedelic-assisted therapy for treating anxiety, depression, and existential distress in people with life-threatening diseases

BACKGROUND

Psychedelic-assisted therapy refers to a group of therapeutic practices involving psychedelics taken under therapeutic supervision from physicians, psychologists, and others. It has been hypothesised that psychedelic-assisted therapy may reduce symptoms of anxiety, depression, and existential distress in patients facing life-threatening diseases (e.g. cancer). However, these substances are illegal in most countries and have been associated with potential risks.

OBJECTIVES

To assess the benefits and harms of psychedelic-assisted therapy compared to placebo or active comparators (e.g. antidepressants) for treatment of anxiety, depression, and existential distress in people with life-threatening diseases.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, and two trial registers on 30 March 2024. In addition, we undertook reference checking, citation searching, and contact with study authors to identify additional studies. We used no language or date restrictions.

SELECTION CRITERIA

We included randomised controlled trials (RCTs), with no restrictions regarding comorbidity, sex, or ethnicity. Interventions comprised a substance-induced psychedelic experience preceded by preparatory therapeutic sessions and followed by integrative therapeutic sessions.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included six studies in the review, which evaluated two different interventions: psychedelic-assisted therapy with classical psychedelics (psilocybin ('magic mushrooms') and lysergic acid diethylamide (LSD)), and psychedelic-assisted therapy with 3,4-methylenedioxymethamphetamine (MDMA or 'Ecstasy'). The studies randomised 149 participants with life-threatening diseases and analysed data for 140 of them. The age range of participants was 36 to 64 years. The studies lasted between 6 and 12 months, and were conducted in outpatient settings in the USA and in Switzerland. Drug companies were not involved in study funding, but funding was provided by organisations that promote psychedelic-assisted therapy. Primary outcomes (at 1 to 12 weeks) Anxiety Psychedelic-assisted therapy using classical psychedelics (psilocybin, LSD) may result in a reduction in anxiety when compared to active placebo (or low-dose psychedelic): State Trait Anxiety Inventory (STAI-Trait, scale 20 to 80) mean difference (MD) -8.41, 95% CI -12.92 to -3.89; STAI-State (scale 20 to 80) MD -9.04, 95% CI -13.87 to -4.21; 5 studies, 122 participants; low-certainty evidence. The effect of psychedelic-assisted therapy using MDMA on anxiety, compared to placebo, is very uncertain: STAI-T MD -14.70, 95% CI -29.45 to 0.05; STAI-S MD -16.10, 95% CI -33.03 to 0.83; 1 study, 18 participants; very low certainty evidence. Depression Psychedelic-assisted therapy using classical psychedelics (psilocybin, LSD) may result in a reduction in depression when compared to active placebo (or low-dose psychedelic): Beck Depression Inventory (BDI, scale 0 to 63) MD -4.92, 95% CI -8.97 to -0.87; 4 studies, 112 participants; standardised mean difference (SMD) -0.43, 95% CI -0.79 to -0.06; 5 studies, 122 participants; low-certainty evidence. The effect of psychedelic-assisted therapy using MDMA on depression, compared to placebo, is very uncertain: BDI-II (scale: 0 to 63) MD -6.30, 95% CI -16.93 to 4.33; 1 study, 18 participants; very low certainty evidence. Existential distress Psychedelic-assisted therapy using classical psychedelics (psilocybin, LSD) compared to active placebo (or low-dose psychedelic) may result in a reduction in demoralisation, one of the most common measures of existential distress, but the evidence is very uncertain (Demoralisation Scale, 1 study, 28 participants): post treatment scores, placebo group 39.6 (SEM 3.4), psilocybin group 18.8 (3.6), P ≤ 0.01). Evidence from other measures of existential distress was mixed. Existential distress was not measured in people receiving psychedelic-assisted therapy with MDMA. Secondary outcomes (at 1 to 12 weeks) Quality of life When classical psychedelics were used, one study had inconclusive results and two reported improved quality of life, but the evidence is very uncertain. MDMA did not improve quality of life measures, but the evidence is also very uncertain. Spirituality Participants receiving psychedelic-assisted therapy with classical psychedelics rated their experience as being spiritually significant (2 studies), but the evidence is very uncertain. Spirituality was not assessed in participants receiving MDMA. Adverse events No treatment-related serious adverse events or adverse events grade 3/4 were reported. Common minor to moderate adverse events for classical psychedelics were elevated blood pressure, nausea, anxiety, emotional distress, and psychotic-like symptoms (e.g. pseudo-hallucination where the participant is aware they are hallucinating); for MDMA, common minor to moderate adverse events were anxiety, dry mouth, jaw clenching, and headaches. Symptoms subsided when drug effects wore off or up to one week later. Certainty of the evidence Although all six studies had intended to blind participants, personnel, and assessors, blinding could not be achieved as this is very difficult in studies investigating psychedelics. Using GRADE criteria, we judged the certainty of evidence to be low to very low, mainly due to high risk of bias and imprecision (small sample size).

AUTHORS' CONCLUSIONS

Implications for practice Psychedelic-assisted therapy with classical psychedelics (psilocybin, LSD) may be effective for treating anxiety, depression, and possibly existential distress, in people facing a life-threatening disease. Psychedelic-assisted therapy seemed to be well tolerated, with no treatment-emergent serious adverse events reported in the studies included in this review. However, the certainty of evidence is low to very low, which means that we cannot be sure about these results, and they might be changed by future research. At the time of this review (2024), psychedelic drugs are illegal in many countries. Implications for research The risk of bias due to 'unblinding' (participants being aware of which intervention they are receiving) could be reduced by measuring expectation bias, checking blinding has been maintained before cross-over, and using active placebos. More studies with larger sample sizes are needed to reduce imprecision. As the US Drug Enforcement Administration (DEA) currently classifies psychedelics as Schedule I substances (i.e. having no accepted medical use and a high potential for abuse), research involving these drugs is restricted, but is steadily increasing.

The serotonergic psychedelic DOI impairs deviance detection in the auditory cortex

Psychedelics are known to induce profound perceptual distortions, yet the neural mechanisms underlying these effects, particularly within the auditory system, remain poorly understood. In this study, we investigated the effects of the psychedelic compound 2,5-Dimethoxy-4-iodoamphetamine (DOI), a serotonin 2A receptor agonist, on the activity of neurons in the auditory cortex of awake mice. We examined whether DOI administration alters sound-frequency tuning, variability in neural responses, and deviance detection (a neural process reflecting the balance between top-down and bottom-up processing). Our results show that while DOI does not alter the frequency selectivity of auditory cortical neurons in a consistent manner, it increases trial-by-trial variability in responses and consistently diminishes the neural distinction between expected (standard) and unexpected (oddball) stimuli. This reduction in deviance detection was primarily driven by a decrease in the response to oddball sounds, suggesting that DOI dampens the auditory cortex's sensitivity to unexpected events. These findings provide insights into how psychedelics disrupt sensory processing and shed light on the neural mechanisms underlying the altered perception of auditory stimuli observed in the psychedelic state.

Large-scale brain connectivity changes following the administration of lysergic acid diethylamide, d-amphetamine, and 3,4-methylenedioxyamphetamine

Psychedelics have recently attracted significant attention for their potential to mitigate symptoms associated with various psychiatric disorders. However, the precise neurobiological mechanisms responsible for these effects remain incompletely understood. A valuable approach to gaining insights into the specific mechanisms of action involves comparing psychedelics with substances that have partially overlapping neurophysiological effects, i.e., modulating the same neurotransmitter systems. Imaging data were obtained from the clinical trial NCT03019822, which explored the acute effects of lysergic acid diethylamide (LSD), d-amphetamine, and 3,4-methylenedioxymethamphetamine (MDMA) in 28 healthy volunteers. The clinical trial employed a double-blind, placebo-controlled, crossover design. Herein, various resting-state connectivity measures were examined, including within-network connectivity (integrity), between-network connectivity (segregation), seed-based connectivity of resting-state networks, and global connectivity. Differences between placebo and the active conditions were assessed using repeated-measures ANOVA, followed by post-hoc pairwise t-tests. Changes in voxel-wise seed-based connectivity were correlated with serotonin 2 A receptor density maps. Compared to placebo, all substances reduced integrity in several networks, indicating both common and unique effects. While LSD uniquely reduced integrity in the default-mode network (DMN), the amphetamines, in contrast to our expectations, reduced integrity in more networks than LSD. However, LSD exhibited more pronounced segregation effects, characterized solely by decreases, in contrast to the amphetamines, which also induced increases. Across all substances, seed-based connectivity mostly increased between networks, with LSD demonstrating more pronounced effects than both amphetamines. Finally, while all substances decreased global connectivity in visual areas, compared to placebo, LSD specifically increased global connectivity in the basal ganglia and thalamus. These findings advance our understanding of the distinctive neurobiological effects of psychedelics, prompting further exploration of their therapeutic potential.

Neurobiological research on N,N-dimethyltryptamine (DMT) and its potentiation by monoamine oxidase (MAO) inhibition: from ayahuasca to synthetic combinations of DMT and MAO inhibitors

The potent hallucinogen N,N-dimethyltryptamine (DMT) has garnered significant interest in recent years due to its profound effects on consciousness and its therapeutic psychopotential. DMT is an integral (but not exclusive) psychoactive alkaloid in the Amazonian plant-based brew ayahuasca, in which admixture of several β-carboline monoamine oxidase A (MAO-A) inhibitors potentiate the activity of oral DMT, while possibly contributing in other respects to the complex psychopharmacology of ayahuasca. Irrespective of the route of administration, DMT alters perception, mood, and cognition, presumably through agonism at serotonin (5-HT) 1A/2A/2C receptors in brain, with additional actions at other receptor types possibly contributing to its overall psychoactive effects. Due to rapid first pass metabolism, DMT is nearly inactive orally, but co-administration with β-carbolines or synthetic MAO-A inhibitors (MAOIs) greatly increase its bioavailability and duration of action. The synergistic effects of DMT and MAOIs in ayahuasca or synthetic formulations may promote neuroplasticity, which presumably underlies their promising therapeutic efficacy in clinical trials for neuropsychiatric disorders, including depression, addiction, and post-traumatic stress disorder. Advances in neuroimaging techniques are elucidating the neural correlates of DMT-induced altered states of consciousness, revealing alterations in brain activity, functional connectivity, and network dynamics. In this comprehensive narrative review, we present a synthesis of current knowledge on the pharmacology and neuroscience of DMT, β-carbolines, and ayahuasca, which should inform future research aiming to harness their full therapeutic potential.

Epigenetic mechanisms of rapid-acting antidepressants

BACKGROUND

Rapid-acting antidepressants (RAADs), including dissociative anesthetics, psychedelics, and empathogens, elicit rapid and sustained therapeutic improvements in psychiatric disorders by purportedly modulating neuroplasticity, neurotransmission, and immunity. These outcomes may be mediated by, or result in, an acute and/or sustained entrainment of epigenetic processes, which remodel chromatin structure and alter DNA accessibility to regulate gene expression.

METHODS

In this perspective, we present an overview of the known mechanisms, knowledge gaps, and future directions surrounding the epigenetic effects of RAADs, with a focus on the regulation of stress-responsive DNA and brain regions, and on the comparison with conventional antidepressants.

MAIN BODY

Preliminary correlative evidence indicates that administration of RAADs is accompanied by epigenetic effects which are similar to those elicited by conventional antidepressants. These include changes in DNA methylation, post-translational modifications of histones, and differential regulation of non-coding RNAs in stress-responsive chromatin areas involved in neurotrophism, neurotransmission, and immunomodulation, in stress-responsive brain regions. Whether these epigenetic changes causally contribute to the therapeutic effects of RAADs, are a consequence thereof, or are unrelated, remains unknown. Moreover, the potential cell type-specificity and mechanisms involved are yet to be fully elucidated. Candidate mechanisms include neuronal activity- and serotonin and Tropomyosine Receptor Kinase B (TRKB) signaling-mediated epigenetic changes, and direct interaction with DNA, histones, or chromatin remodeling complexes.

CONCLUSION

Correlative evidence suggests that epigenetic changes induced by RAADs accompany therapeutic and side effects, although causation, mechanisms, and cell type-specificity remain largely unknown. Addressing these research gaps may lead to the development of novel neuroepigenetics-based precision therapeutics.

A Cross-Sectional Survey Investigating Māori and Non-Māori Cancer Patients' Views on Psychedelic-Assisted Therapy in Aotearoa New Zealand

People with cancer experience higher rates of psychological dysfunction than the general population, with extreme inequity among indigenous people. Psychedelic-assisted therapy (PAT) is a reemerging area with promising evidence as a treatment for mental health difficulties. The current study aimed to investigate the perceptions of PAT in indigenous (Māori) and non-indigenous cancer patients in Aotearoa, New Zealand. Eighty-five cancer patients (Māori n = 32, non-Māori n = 53) completed a brief anonymous survey assessing demographics, psychological factors, and awareness and perceptions of PAT. Participants were recruited online (via social media and cancer support e-mail lists) and in person at Auckland City Hospital. Maori had significantly poorer psychological well-being than non-Māori. All participants had low awareness of this novel treatment and held largely neutral attitudes. Regression analyses revealed that predictors of more favorable attitudes toward PAT included greater awareness of psychedelics, advanced cancer stage, younger age, poorer holistic well-being, greater demoralization, and prioritizing treatment effectiveness over possible risks and uncertainty. The current study provides a foundational step in exploring perceptions toward PAT in indigenous and non-indigenous groups. These results have the potential to shape future research trials investigating PAT and further highlight the importance of indigenous involvement in the psychedelic research space.

Psychoactive substances for the treatment of neuropsychiatric disorders

In the contemporary landscape of psychiatric medicine, critical advancements have been noted in the utilization of psychoactive substances such as hallucinogens, 3,4-methylenedioxymethamphetamine (MDMA), and ketamine for the treatment of severe mental health disorders. This review provides a detailed evaluation of these substances, focusing on their mechanisms of action and the profound clinical outcomes observed in controlled environments. Hallucinogens like lysergic acid diethylamide and psilocybin primarily target the 5-HT2A receptor agonist-2 (5-HT2AR), inducing substantial perceptual and cognitive shifts that facilitate deep psychological introspection and significant therapeutic advances, particularly in patients suffering from depression and anxiety disorders. MDMA, influencing multiple neurotransmitter systems including 5-Hydroxytryptamine (5-HT), dopamine, and norepinephrine, has been demonstrated to effectively alleviate symptoms of post-traumatic stress disorder, enhancing patients' emotional engagement and resilience during psychotherapy. Meanwhile, ketamine, a glutamate receptor antagonist, rapidly alleviates depressive symptoms, offering a lifeline for individuals with treatment-resistant depression through its fast-acting antidepressant properties. The integration of these substances into psychiatric practice has shown promising results, fundamentally changing the therapeutic landscape for patients unresponsive to traditional treatment modalities. However, the potent effects of these agents also necessitate a cautious approach in clinical application, ensuring careful dosage control, monitoring, and risk management to prevent potential abuse and mitigate adverse effects.

Mind over matter: the microbial mindscapes of psychedelics and the gut-brain axis

Psychedelics have emerged as promising therapeutics for several psychiatric disorders. Hypotheses around their mechanisms have revolved around their partial agonism at the serotonin 2 A receptor, leading to enhanced neuroplasticity and brain connectivity changes that underlie positive mindset shifts. However, these accounts fail to recognise that the gut microbiota, acting via the gut-brain axis, may also have a role in mediating the positive effects of psychedelics on behaviour. In this review, we present existing evidence that the composition of the gut microbiota may be responsive to psychedelic drugs, and in turn, that the effect of psychedelics could be modulated by microbial metabolism. We discuss various alternative mechanistic models and emphasize the importance of incorporating hypotheses that address the contributions of the microbiome in future research. Awareness of the microbial contribution to psychedelic action has the potential to significantly shape clinical practice, for example, by allowing personalised psychedelic therapies based on the heterogeneity of the gut microbiota.

Psychotropic Drugs Reemerging as Headache Medicines

Scientific and public attention on the therapeutic effects of psychedelics and other psychoactive compounds in headache disorders has recently grown. The use and reported therapeutic effects of such treatments have long been reported, though formal clinical trials are only recently taking place. When considering how these substances might be further studied and eventually applied, it is important to consider the specific headache disorder, the particular drug, and the mode of use. No singular protocol will be applicable across all headache disorders and drugs. In this leading article, the nuance required to consider the value of classic psychedelics, ketamine, and cannabinoids as headache medicines is presented.

Novel psychoplastogen DM506 reduces cue-induced heroin-seeking and inhibits tonic GABA currents in the Prelimbic Cortex

Opioid use disorder is a major public health crisis that is manifested by persistent drug-seeking behavior and high relapse frequency. Most of the available treatments rely on targeting opioid receptors using small molecules that do not provide sustained symptom alleviation. Psychoplastogens are a novel class of non-opioid drugs that produce rapid and sustained effects on neuronal plasticity, intended to produce therapeutic benefits. Ibogalogs are synthetic derivatives of iboga alkaloids that lack hallucinogenic or adverse side effects. In the current study, we examine the therapeutic potential of DM506, a novel ibogalog lacking any cardiotoxic or hallucinogenic effects, in cue-induced seeking behavior following heroin self-administration. At a single systemic dose of 40 mg/kg, DM506 significantly decreased cue-induced seeking in both male and female rats at abstinence day 1 (AD1) following heroin self-administration. Upon re-testing for cue-induced seeking at AD14, we found that males receiving DM506 continued to show decreased cue-induced seeking, an effect not observed in females. Since there is evidence of psychedelics influencing tonic GABA currents, and opioid and psychoplastogen-mediated neuroadaptations in the medial prefrontal cortex (PrL) underlying its functional effects, we performed patch-clamp recordings on PrL slices of drug-naïve rats with an acute application or chronic incubation with DM506. Tonic GABA current was decreased in slices incubated with DM506 for 2 h. qPCR analysis did not reveal any differences in the mRNA levels of GABAA receptor α and δ subunits at AD14 in heroin and saline self-administered animals that received vehicle or DM506 at AD1. Overall, our data indicate that DM506 attenuates cue-induced heroin seeking and inhibits tonic GABA current in the prelimbic cortex.

Effects of psilocybin on uncertain punishment learning

Psilocybin may provide a useful treatment for mood disorders including anxiety and depression but its mechanisms of action for these effects are not well understood. While recent preclinical work has begun to assess psilocybin's role in affective behaviors through innate anxiety or fear conditioning, there is scant evidence for its role in conflict between reward and punishment. The current study was designed to determine the impact of psilocybin on the learning of reward-punishment conflict associations, as well as its effects after learning, in male and female rats. We utilized a chained schedule of reinforcement that involved execution of safe and risky reward-guided actions under uncertain punishment. Different patterns of behavioral suppression by psilocybin emerged during learning versus after learning of risky action-reward associations. Psilocybin increased behavioral suppression in female rats as punishment associations were learned. After learning, psilocybin decreased behavioral suppression in both sexes. Thus, psilocybin produces divergent effects on action suppression during approach-avoidance conflict depending on when the conflict is experienced. This observation may have implications for its therapeutic mechanism of action.

Psychedelics in Psychiatry, the Nursing Influence, and the Future of Psychedelic Therapies

OBJECTIVE

Psychedelics and psychedelic-assisted therapies (PATs) are on the cusp of becoming medicalized treatment modalities within the United States, both as potential U.S. Food and Drug Administration (FDA)-approved treatment and therapeutic options outside the medical model, through decriminalization efforts within individual states. Bringing with it a paradigm shift in the delivery of health care for both physical and mental health treatment. A workforce of highly trained facilitators will be needed to meet the anticipated demand for this type of treatment and nurses can play a key role in meeting this demand. This article serves to introduce psychedelic-assisted therapies to psychiatric-mental health nurses as we start to see this new field emerge.

METHOD

Review of published literature and other media.

RESULTS

Results based on historical data, modern applications, and future considerations.

CONCLUSIONS

Nurses have been involved with psychedelic-assisted therapies in the past and are fully capable of providing a wide range of roles upon the anticipated approval as a treatment modality.

Pharmacological fingerprint of antipsychotic drugs at the serotonin 5-HT2A receptor

The intricate involvement of the serotonin 5-HT2A receptor (5-HT2AR) both in schizophrenia and in the activity of antipsychotic drugs is widely acknowledged. The currently marketed antipsychotic drugs, although effective in managing the symptoms of schizophrenia to a certain extent, are not without their repertoire of serious side effects. There is a need for better therapeutics to treat schizophrenia for which understanding the mechanism of action of the current antipsychotic drugs is imperative. With bioluminescence resonance energy transfer (BRET) assays, we trace the signaling signature of six antipsychotic drugs belonging to three generations at the 5-HT2AR for the entire spectrum of signaling pathways activated by serotonin (5-HT). The antipsychotic drugs display previously unidentified pathway preference at the level of the individual Gα subunits and β-arrestins. In particular, risperidone, clozapine, olanzapine and haloperidol showed G protein-selective inverse agonist activity. In addition, G protein-selective partial agonism was found for aripiprazole and cariprazine. Pathway-specific apparent dissociation constants determined from functional analyses revealed distinct coupling-modulating capacities of the tested antipsychotics at the different 5-HT-activated pathways. Computational analyses of the pharmacological and structural fingerprints support a mechanistically based clustering that recapitulate the clinical classification (typical/first generation, atypical/second generation, third generation) of the antipsychotic drugs. The study provides a new framework to functionally classify antipsychotics that should represent a useful tool for the identification of better and safer neuropsychiatric drugs and allows formulating hypotheses on the links between specific signaling cascades and in the clinical outcomes of the existing drugs.

Distinct 5-HT receptor subtypes regulate claustrum excitability by serotonin and the psychedelic, DOI

Recent evidence indicates that neuronal activity within the claustrum (CLA) may be central to cellular and behavioral responses to psychedelic hallucinogens. The CLA prominently innervates many cortical targets and displays exceptionally high levels of serotonin (5-HT) binding. However, the influence of serotonin receptors, prime targets of psychedelic drug action, on CLA activity remains unexplored. We characterize the CLA expression of all known 5-HT subtypes and contrast the effects of 5-HT and the psychedelic hallucinogen, 2,5-dimethoxy-4-iodoamphetamine (DOI), on excitability of cortical-projecting CLA neurons. We find that the CLA is particularly enriched with 5-HT2C receptors, expressed predominantly on glutamatergic neurons. Electrophysiological recordings from CLA neurons that project to the anterior cingulate cortex (ACC) indicate that application of 5-HT inhibits glutamate receptor-mediated excitatory postsynaptic currents (EPSCs). In contrast, application of DOI stimulates EPSCs. We find that the opposite effects of 5-HT and DOI on synaptic signaling can both be reversed by inhibition of the 5-HT2C, but not 5-HT2A, receptors. We identify specific 5-HT receptor subtypes as serotonergic regulators of the CLA excitability and argue against the canonical role of 5-HT2A in glutamatergic synapse response to psychedelics within the CLA-ACC circuit.

The role of psilocybin in depressive disorders

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

Nascimento J, Domith I, Karmirian K, Feilding A, Trindade P, Martins-de-Souza D, K. Rehen S. LSD Modulates Proteins Involved in Cell Proteostasis, Energy Metabolism and Neuroplasticity in Human Cerebral Organoids

Proteomic analysis of human cerebral organoids may reveal how psychedelics regulate biological processes, shedding light on drug-induced changes in the brain. This study elucidates the proteomic alterations induced by lysergic acid diethylamide (LSD) in human cerebral organoids. By employing high-resolution mass spectrometry-based proteomics, we quantitatively analyzed the differential abundance of proteins in cerebral organoids exposed to LSD. Our findings indicate changes in proteostasis, energy metabolism, and neuroplasticity-related pathways. Specifically, LSD exposure led to alterations in protein synthesis, folding, autophagy, and proteasomal degradation, suggesting a complex interplay in the regulation of neural cell function. Additionally, we observed modulation in glycolysis and oxidative phosphorylation, crucial for cellular energy management and synaptic function. In support of the proteomic data, complementary experiments demonstrated LSD's potential to enhance neurite outgrowth in vitro, confirming its impact on neuroplasticity. Collectively, our results provide a comprehensive insight into the molecular mechanisms through which LSD may affect neuroplasticity and potentially contribute to therapeutic effects for neuropsychiatric disorders.

Rapid effects of tryptamine psychedelics on perceptual distortions and early visual cortical population receptive fields

N, N-dimethyltryptamine (DMT) is a psychedelic tryptamine acting on 5-HT2A serotonin receptors, which is associated with intense visual hallucinatory phenomena and perceptual changes such as distortions in visual space. The neural underpinnings of these effects remain unknown. We hypothesised that changes in population receptive field (pRF) properties in the primary visual cortex (V1) might underlie visual perceptual experience. We tested this hypothesis using magnetic resonance imaging (MRI) in a within-subject design. We used a technique called pRF mapping, which measures neural population visual response properties and retinotopic maps in early visual areas. We show that in the presence of visual effects, as documented by the Hallucinogen Rating Scale (HRS), the mean pRF sizes in V1 significantly increase in the peripheral visual field for active condition (inhaled DMT) compared to the control. Eye and head movement differences were absent across conditions. This evidence for short-term effects of DMT in pRF may explain perceptual distortions induced by psychedelics such as field blurring, tunnel vision (peripheral vision becoming blurred while central vision remains sharp) and the enlargement of nearby visual space, particularly at the visual locations surrounding the fovea. Our findings are also consistent with a mechanistic framework whereby gain control of ongoing and evoked activity in the visual cortex is controlled by activation of 5-HT2A receptors.

Role of the circadian nuclear receptor REV-ERBα in dorsal raphe serotonin synthesis in mood regulation

Affective disorders are frequently associated with disrupted circadian rhythms. The existence of rhythmic secretion of central serotonin (5-hydroxytryptamine, 5-HT) pattern has been reported; however, the functional mechanism underlying the circadian control of 5-HTergic mood regulation remains largely unknown. Here, we investigate the role of the circadian nuclear receptor REV-ERBα in regulating tryptophan hydroxylase 2 (Tph2), the rate-limiting enzyme of 5-HT synthesis. We demonstrate that the REV-ERBα expressed in dorsal raphe (DR) 5-HTergic neurons functionally competes with PET-1-a nuclear activator crucial for 5-HTergic neuron development. In mice, genetic ablation of DR 5-HTergic REV-ERBα increases Tph2 expression, leading to elevated DR 5-HT levels and reduced depression-like behaviors at dusk. Further, pharmacological manipulation of the mice DR REV-ERBα activity increases DR 5-HT levels and affects despair-related behaviors. Our findings provide valuable insights into the molecular and cellular link between the circadian rhythm and the mood-controlling DR 5-HTergic systems.

Dynamic medial parietal and hippocampal deactivations under DMT relate to sympathetic output and altered sense of time, space, and the self

N,N-Dimethyltryptamine (DMT) is a serotonergic psychedelic, known to rapidly induce short-lasting alterations in conscious experience, characterized by a profound and immersive sense of physical transcendence alongside rich and vivid auditory distortions and visual imagery. Multimodal neuroimaging data paired with dynamic analysis techniques offer a valuable approach for identifying unique signatures of brain activity - and linked autonomic physiology - naturally unfolding during the altered state of consciousness induced by DMT. We leveraged simultaneous fMRI and EKG data acquired in 14 healthy volunteers prior to, during, and after intravenous administration of DMT, and, separately, placebo. fMRI data was preprocessed to derive individual dynamic activity matrices, reflecting the similarity of brain activity in time, and community detection algorithms were applied on these matrices to identify brain activity substates; EKG data was used to derive continuous heart rate. We identified a brain substate occurring immediately after DMT injection, characterized by hippocampal and medial parietal deactivations and increased superior temporal lobe activity under DMT. Deactivations in the hippocampus and medial parietal cortex correlated with alterations in the usual sense of time, space and self-referential processes, reflecting a deconstruction of essential features of ordinary consciousness. Superior lobe activations instead correlated with audio/visual hallucinations and experience of " entities ", reflecting the emergence of altered sensory experiences under DMT. Finally, increased heart rate under DMT correlated positively with hippocampus/medial parietal deactivation and the experience of " entities ", and negatively with altered self-referential processes. These results suggest a chain of influence linking sympathetic regulation to hippocampal and medial parietal deactivations under DMT, which combined, may contribute to positive mental health outcomes related to self-referential processing following psychedelic administration.

Lysergic acid diethylamide induces behavioral changes in Caenorhabditis elegans

Lysergic acid diethylamide (LSD) is a synthetic psychedelic compound with potential therapeutic value for psychiatric disorders. This study aims to establish Caenorhabditis elegans as an in vivo model for examining LSD's effects on locomotor behavior. Our results demonstrate that LSD is absorbed by C. elegans and that the acute treatment reduces animal speed, similar to the role of endogenous serotonin. This response is mediated in part by the serotonergic receptors SER-1 and SER-4. Our findings highlight the potential of this nematode as a new experimental model in psychedelic research.

Psilocybin and chronic neuropathic pain: a systematic review

BACKGROUND/IMPORTANCE

Chronic pain affects many people globally, requiring alternative management strategies. Psilocybin is gaining attention for its potential in chronic pain management despite being classified as Schedule I.

OBJECTIVE

This systematic review critically evaluates the evidence for psilocybin, a Schedule I substance, in the treatment of chronic pain. The exact purpose of the review is to assess the impact of psilocybin on chronic pain relief, focusing on dosing protocols, treated conditions, and patient outcomes.

EVIDENCE REVIEW

A comprehensive review of PubMed, CINAHL, Web of Science, Cochrane Library, and EMBASE was conducted up to January 2024. Eligibility criteria included studies evaluating psilocybin for chronic pain management. The risk of bias was assessed using the MASTER (MethodologicAl STandards for Epidemiological Research) scale, and the strength of evidence was graded using GRADE (Grading of Recommendations, Assessment, Development, and Evaluation).

FINDINGS

The review identified 28 relevant studies focusing on dosing, treated conditions, and outcomes. The majority of the included studies (76.2%) were of low or very low quality. Several studies with moderate-to-low-quality evidence utilized a 0.14 mg/kg dosing protocol. The findings suggest promise for the use of psilocybin in chronic pain relief, though the quality of evidence is generally low.

CONCLUSIONS

The current research shows potential for psilocybin as a treatment option for chronic pain relief. However, methodological issues and a lack of high-quality evidence underscore the need for further investigations with standardized protocols. Despite these limitations, the potential for psilocybin in chronic pain management is encouraging.

PROSPERO REGISTRATION NUMBER

CRD42023493823.

Exploring psychedelic use in athletes and their attitudes toward psilocybin-assisted therapy in concussion recovery

Background

Psychedelics are receiving growing interest among clinical researchers for their effects on mood and cognition. Psilocybin is one of the most widely studied classic psychedelics which has shown good safety and clinical benefit for major depression and substance use disorders. Athletes frequently sustain concussions and often experience myriad symptoms, including cognitive and mood issues, which can persist for weeks or months in 10%-30% of athletes. Psilocybin may be a potential symptom management option for athletes with persisting concussion symptoms.

Objectives

This study sought to summarize athlete psychedelic use, among other substances, and to examine the willingness of the sports community to engage in or support psilocybin-assisted therapy (PAT) for concussion recovery and management of persisting concussion symptoms.

Methods

In total, 175 (n = 85 athletes; n = 90 staff) respondents completed an online survey distributed in Canada and the United States which queried sport involvement and demographics, substance use, concussion history, and knowledge and willingness about psilocybin. The reporting of this study conforms to the Checklist for Reporting Results of Internet E-Surveys (CHERRIES) statement.

Design

Substance use rates were summarized across athletes and team staff members and a path analysis was used for each sample to identify predictors of willingness to use PAT (athletes) or support PAT (staff) for concussion recovery. Participants were also asked to identify perceived barriers to the implementation of PAT for sports-related concussions, and to indicate their overall willingness.

Results

Psychedelics were the third most used substance in the past year among athletes (35.8%) while regular psychedelic use was quite low in athletes (7.5%). A path analysis conducted in RStudio found that attitudes toward psilocybin and knowledge of psilocybin were significant predictors for both athletes and staff members of their willingness to use or support PAT for concussion recovery. Athletes reported likely engaging in PAT (61.2%) and staff (71.1%) reported that they would support their athletes using PAT.

Conclusion

The results of this study suggest that the sports community may be receptive to PAT and athletes would be willing to engage in it for concussion recovery and/or the management of persisting post-concussion symptoms (PPCS). Future research should examine the effects of psilocybin for PPCS to inform whether there is any impact while addressing concerns regarding long-term effects of psilocybin use.

Visual hallucinations originating in the retinofugal pathway under clinical and psychedelic conditions

Psychedelics like LSD (Lysergic acid diethylamide) and psilocybin are known to modulate perceptual modalities due to the activation of mostly serotonin receptors in specific cortical (e.g., visual cortex) and subcortical (e.g., thalamus) regions of the brain. In the visual domain, these psychedelic modulations often result in peculiar disturbances of viewed objects and light and sometimes even in hallucinations of non-existent environments, objects, and creatures. Although the underlying processes are poorly understood, research conducted over the past twenty years on the subjective experience of psychedelics details theories that attempt to explain these perceptual alterations due to a disruption of communication between cortical and subcortical regions. However, rare medical conditions in the visual system like Charles Bonnet syndrome that cause perceptual distortions may shed new light on the additional importance of the retinofugal pathway in psychedelic subjective experiences. Interneurons in the retina called amacrine cells could be the first site of visual psychedelic modulation and aid in disrupting the hierarchical structure of how humans perceive visual information. This paper presents an understanding of how the retinofugal pathway communicates and modulates visual information in psychedelic and clinical conditions. Therefore, we elucidate a new theory of psychedelic modulation in the retinofugal pathway.

Naturalistic use of psychedelics does not modulate processing of self-related stimuli (but it might modulate attentional mechanisms): An event-related potentials study

Classic psychedelics are able to profoundly alter the state of consciousness and lead to acute experiences of ego dissolution - the blurring of the distinction between representations of self and the external world. However, whether repeated use of psychedelics is associated with more prolonged and permanent modifications to the concept of self remains to be investigated. Therefore, we conducted a preregistered, cross-sectional study in which experienced psychedelics users (15 or more lifetime experiences with psychedelics; N = 56) were compared to nonusers (N = 57) in terms of neural reactivity to a Self-name (i.e., each participant's own name) stimulus, which is known to robustly activate a representation of self. Two control stimuli were additionally used: an Other-name stimulus, as a passive control condition in which no reaction was required, and a Target-name stimulus, to which participants provided a manual response and which thus constituted an active control condition. Analysis of the amplitude of the P300 ERP component evoked by the Self- or Target-names revealed no difference between the psychedelics users and nonusers. However, psychedelic users exhibited increased P300 amplitude during perception of Other-names. In addition, in comparison to nonusers, psychedelics users exhibited a smaller increase in P300 amplitude when processing the task-relevant Target-names (in relation to both Self- and Other-names). Therefore, our data suggests that regular naturalistic use of psychedelics may not be related to long-term changes in the representation of self, but it might potentially affect the allocation of attentional resources to task-relevant stimuli.

The Global Psychedelic Survey: Consumer characteristics, patterns of use, and access in primarily anglophone regions around the world

OBJECTIVES

Despite advancements in policies governing psychedelic substances globally, our understanding of real-world psychedelic use and its variations across international jurisdictions remains limited. We implemented the Global Psychedelic Survey (GPS) to capture information about psychedelic consumer characteristics, access, and usage patterns around the world.

METHODS

The GPS was administered online in Spring 2023 to English-speaking adults (≥21 years) who use(d) psychedelics. We categorized survey responses into major catchment regions (Canada/US, Europe/UK, Australia/NZ, All Other). We used descriptive and bivariable statistics to characterize consumers' socio-demographic characteristics, psychedelic access sources, and usage patterns. We examined regional differences in psychedelic use patterns using multinomial logistic regression.

RESULTS

We analyzed 6379 responses from 85 countries including Canada/US (n = 4434), Europe/UK (n = 771), Australia/NZ (n = 864), and Other (n = 310). Psilocybin, LSD, and MDMA were the most used psychedelics and personal growth was the most common use motive across all catchments. There were significant regional differences in psychedelic use patterns, including types of psychedelics used (e.g., less ibogaine use in Europe/UK and Australia/NZ relative to Canada/US), frequency of use (e.g., lower frequency use in Australia/NZ relative to Canada/US), motivations for use (e.g., less therapeutic use in Europe/UK and Other relative to Canada/US), and types of dosing regimens (e.g., more "micro"-dosing in Canada/US).

DISCUSSION

In this large sample of adult psychedelic consumers from regions around the world, infrequent psychedelic use centered around life enhancement was common. Respondents indicated preference for legal access via quality-controlled sources. Jurisdictional differences in access and usage patterns likely reflect region-specific regulations and traditional practices. Further research should explore opportunities to increase representation of non-White respondents in psychedelic research via translation of studies into several languages and incorporation of culturally reflective, community-based study development.

Phase 1, placebo-controlled, single ascending dose trial to evaluate the safety, pharmacokinetics and effect on altered states of consciousness of intranasal BPL-003 (5-methoxy-N,N-dimethyltryptamine benzoate) in healthy participants

AIMS

To investigate the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of BPL-003, a novel intranasal benzoate salt formulation of 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT), in healthy participants.

METHODS

In all, 44 psychedelic-naïve participants enrolled in the double-blind, placebo-controlled single ascending dose study (1-12 mg BPL-003). Concentrations of 5-MeO-DMT and its pharmacologically active metabolite, bufotenine, were determined in plasma and urine. PD endpoints included subjective drug intensity (SDI) rating, the Mystical Experience Questionnaire (MEQ-30) and the Ego Dissolution Inventory (EDI).

RESULTS

BPL-003 was well tolerated at doses up to 12 mg. There were no serious adverse events (AEs), and most AEs were mild; the most common being nasal discomfort, nausea, headache and vomiting. 5-MeO-DMT was rapidly absorbed and eliminated; the median time to peak plasma concentration was approximately 8-10 min and the mean terminal elimination half-life was <27 min. 5-MeO-DMT systemic exposure increased approximately dose-proportionally, while plasma bufotenine concentrations and urinary excretion of 5-MeO-DMT and bufotenine were negligible. The intensity of the SDI ratings was associated with plasma 5-MeO-DMT concentrations. MEQ-30 and EDI scores generally increased with the BPL-003 dose; 60% of participants had a 'complete mystical experience' at 10 and 12 mg doses. Profound and highly emotional consciousness-altering effects were observed with BPL-003, with a rapid onset and short-lasting duration.

CONCLUSION

The novel intranasal formulation of BPL-003 was well tolerated with dose-proportional increases in PK and PD effects. The short duration of action and induction of mystical experiences suggest clinical potential, warranting further trials.

CLINICAL TRIAL REGISTRATION

NCT05347849.

Clinical Effects of Psychedelic Substances Reported to United States Poison Centers: 2012 to 2022

STUDY OBJECTIVE

Psychedelic substances use is increasing in the United States (US). The approval of new psychedelic drugs and legalization of natural psychedelic substances will likely further increase exposures and subsequent adverse events. The study objective is to describe the clinical effects, therapies, and medical outcomes of patients with psychedelic exposures reported to US poison centers.

METHODS

We performed a retrospective, cross-sectional study on psychedelic exposures reported to the National Poison Data System from January 1, 2012, to December 31, 2022. We categorized exposures into groups: hallucinogenic amphetamines, lysergic acid diethylamide, tryptamines (such as N, N-dimethyltryptamine), phencyclidine, hallucinogenic mushrooms, hallucinogenic plants, and ketamine and ketamine analogs. We summarized effects, treatments, and outcomes and evaluated associations with logistic regression and odds ratios.

RESULTS

Our sample included 54,605 cases. There were concomitant exposures in 41.1% (n=22,460) of cases. Hallucinogenic mushroom exposures increased most over the study period from 593 in 2012 to 1,440 in 2022. Overall, 27,444 (50.3%) psychedelic exposures had symptoms that required treatment, severe residual or prolonged symptoms, or death. Cardiovascular effects were common, especially with hallucinogenic amphetamine exposures (31.1%). Patients managed in or referred to a health care facility received medical therapies in 62.4% of cases, including sedation (32.9%) and respiratory interventions (10.3%).

CONCLUSION

Over half of psychedelic exposures reported to US poison centers had symptoms that required treatment, severe residual or prolonged symptoms, or death. Increases in psychedelic use may lead to increased frequency of adverse events and health care utilization.

Content analysis of Reddit posts about coadministration of selective serotonin reuptake inhibitors and psilocybin mushrooms

RATIONALE

Treatments with the serotonergic psychedelic psilocybin are being investigated for multiple neuropsychiatric disorders. Because many patients with these disorders use selective serotonin reuptake inhibitors (SSRIs), understanding interactions between psilocybin and SSRIs is critical for evaluating the safety, efficacy, and scalability of psilocybin-based treatments. Current knowledge about these interactions is limited, as most clinical psilocybin research has prohibited concomittant SSRI use.

OBJECTIVES

We aimed to explore potential interactions between psilocybin and SSRIs by characterizing peoples' real-world experiences using psilocybin mushrooms and SSRIs together.

METHODS

We conducted a systematic search of Reddit for posts describing psilocybin mushroom and SSRI coadministration. We identified 443 eligible posts and applied qualitative content analysis to each.

RESULTS

8% of posts reported negative physical or psychological effects resulting from coadministration. These included 13 reports that may reflect serotonin toxicity, and 1 concerning for a psychotic/manic episode. 54% of posts described reduced intensity of the acute psilocybin experience, but 39% reported unchanged intensity with SSRI coadministration.

CONCLUSIONS

Psilocybin's interactions with SSRIs are likely complex and may depend on multiple factors. Prospective studies are needed to evaluate whether psilocybin treatments are reliably safe and effective in the setting of SSRI use.

[The nursing role in psychedelic-assisted psychotherapy]

In this article, we aim to highlight the specific role of nurses in the interdisciplinary model of psychedelic-assisted psychotherapy. We argue that the plural competencies of our profession are at the heart of future issues in psychiatry and the use of psychedelics.

From chaos to kaleidoscope: Exploring factors in psychedelic self-treatment for mental health conditions

INTRODUCTION

This study explores how individuals self-treat psychiatric conditions with psychedelics outside medical guidance bridging the gap in understanding unregulated therapeutic use.

AIMS

The primary objective was to extract specific factors underlying the effects of psychedelics, exploring their relationship with the need for medication, particularly for mental health conditions like depression and anxiety. Additionally, we aimed to understand how the likelihood of being prescribed pharmacological medication varies based on mental health diagnoses and demographic factors.

METHODS

This research utilised the Global Drug Survey 2020, an annual online survey focused on substance use patterns and demographics, incorporating modules addressing mental health and psychedelic use. The study employed Exploratory Factor Analysis to discern latent factors underlying the self-reported effects of psychedelics. Bivariable and multivariable logistic regressions were conducted to investigate the association between identified factors and the likelihood of current prescribed medication usage.

RESULTS

In all, 2552 respondents reported using psychedelics for self-treatment of mental health conditions. Three significant factors were identified: Improved Mental Health, Improved Self-Awareness and Neuro-Sensory Changes. The majority of the sample reported a history of depression (80%) or anxiety (65.6%), with a significant association observed between reported factors of psychedelics' effects and current medication usage for mental health, especially notable in cases of depression or comorbid depression and anxiety.

CONCLUSIONS

Perceived symptom improvement following psychedelic self-treatment may reduce the need for medically supervised pharmacological interventions. These findings highlight the potential of psychedelics to positively influence mental health and self-awareness, paving the way for further research into their therapeutic application.

Toxicology and Pharmacological Interactions of Classic Psychedelics

As psychedelics are being investigated for more medical indications, it has become important to characterize the adverse effects and pharmacological interactions with these medications. This chapter will summarize what is known about the toxicology and drug-drug interactions for classic psychedelics, such as LSD, psilocybin, DMT, 5-MeO-DMT, mescaline, 2C-B, Bromo-DragonFLY, and 25X-NBOMe.

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.

Effects of psychedelic, DOI, on nucleus accumbens dopamine signaling to predictable rewards and cues in rats

Psychedelics produce lasting therapeutic responses in neuropsychiatric diseases suggesting they may disrupt entrenched associations and catalyze learning. Here, we examine psychedelic 5-HT2A/2C agonist, DOI, effects on dopamine signaling in the nucleus accumbens (NAc) core, a region extensively linked to reward learning, motivation, and drug-seeking. We measure phasic dopamine transients following acute DOI administration in rats during well learned Pavlovian tasks in which sequential cues predict rewards. We find that DOI (0.0-1.2 mg/kg, i.p.) increases dopamine signals, photometrically measured using GRABDA optical sensor, to rewards and proximal reward cues, but not to the distal cues that predict these events. We determine that the elevated dopamine produced by DOI to reward cues occurs independently of DOI-induced changes in reward value. The increased dopamine associated with predictable reward cues and rewards supports DOI-induced increases in prediction error signaling. These findings lay a foundation for developing psychedelic strategies aimed at engaging error-driven learning mechanisms to disrupt entrenched associations or produce new associations.

A rapid narrative review of the clinical evolution of psychedelic treatment in clinical trials

Pre-prohibition psychedelic research with complex psychiatric patients generated a wealth of treatment methodologies and practices, providing invaluable clinical insights pertaining to the medical administration of psychedelics in various mental health diagnoses. Building upon these early studies, which lack the rigor and research tools available today, contemporary psychedelic research has focused on investigating the safety and efficacy of psychedelics in randomized controlled trials via psychometric measures and symptom assessments. Both then and now, the treatment context and the role of clinicians in psychedelic treatment has been recognized as an essential feature for positive patient outcomes. To broaden the knowledge base of modern psychedelic research and support the training of clinicians conducting medically supervised psychedelic research studies, this paper provides a review of pre-prohibition clinical research narratives pertaining to the phenomenology of psychedelic treatment and the role of the non-pharmacological treatment factors in the patient experience. Lastly, this paper explores a range of clinician perspectives and psychological interventions employed in pre-prohibition psychedelic research to inform future research directions and best practice guidelines.

Serine 3.39 and isoleucine 4.60 are key sites for 5-HT2AR-mediated Gs signaling

Certain amino acid sites of 5-HT2AR play crucial roles in interacting with various G proteins. Hallucinogens and non-hallucinogens both act on 5-HT2AR but mediate different pharmacological effects, possibly due to the coupling of different G proteins. Therefore, this study identified the binding sites of hallucinogens and non-hallucinogens with 5-HT2AR through molecular docking. We conducted site mutation to examine the impact of these sites on G proteins, in order to find out the sites that can distinguish the pharmacological effects of hallucinogens and non-hallucinogens. Our results indicate that I4.60A and S3.39A did not affect the ability of hallucinogens to activate Gq signaling, but significantly reduced Gs signaling activation by hallucinogens. These results suggest that S3.39 and I4.60 are important for the activation of Gs signaling by hallucinogens.