Psychedelics as anti-inflammatory agents

Psilocybin: From Psychiatric Pariah to Perceived Panacea

OBJECTIVE

The authors critically examine the evidence base for psilocybin administered with psychological support/therapy (PST) in the treatment of psychiatric disorders and offer practical recommendations to guide future research endeavors.

METHODS

PubMed was searched for English-language articles from January 1998 to November 2023, using the search term "psilocybin." A total of 1,449 articles were identified and screened through titles and abstracts. Of these, 21 unique open-label or randomized controlled trials (RCTs) were identified that examine psilocybin for the treatment of obsessive-compulsive and related disorders (N=2), anxiety/depression associated with a cancer diagnosis (N=5), major depressive disorder (MDD; N=8), substance use disorders (N=4), anorexia (N=1), and demoralization (i.e., hopelessness, helplessness, and poor coping) in AIDS survivors (N=1).

RESULTS

The most developed evidence base is for the treatment of MDD (three double-blind RCTs with positive signals spanning a range of severities). However, the evidence is tempered by threats to internal and external validity, including unsuccessful blinding, small samples, large variability in dosing and PST procedures, limited sample diversity, and possibly large expectancy effects. Knowledge of mechanisms of action and predictors of response is currently limited.

CONCLUSIONS

The evidence is currently insufficient to recommend psilocybin with PST as a psychiatric treatment. Additional rigorously designed clinical trials are needed to definitively establish efficacy in larger and more diverse samples, address dosing considerations, improve blinding, and provide information on mechanisms of action and moderators of clinical response. Head-to-head comparisons with other evidence-based treatments will better inform the potential future role of psilocybin with PST in the treatment of major psychiatric disorders.

Concurrent stress modulates the acute and post-acute effects of psilocybin in a sex-dependent manner

There is renewed interest in psychedelics, such as psilocybin, as therapies for multiple difficult-to-treat psychiatric disorders. Even though psychedelics can induce highly pleasant or aversive experiences, depending on multiple personal and environmental factors, there is little research into how such experiences impact post-acute mood-altering actions. Here we aimed at offsetting this gap. First, we tested whether acute psilocybin effects differed between sexes. Adult male and female C57BL/6J mice received saline or psilocybin (5mg/kg;i.p.), and head-twitch response (HTR) frequency was quantified. Notably, while psilocybin increased HTR frequency in both sexes, the effect was greater in females. We then tested if stress exposure during acute drug effects impacted post-acute psilocybin actions. Following drug treatment, mice were returned to their homecage or restrained for 1h. Anxiety- and depressive-like behaviors were assessed starting 24h following drug administration, using the marble burying, novelty-suppressed feeding, and splash tests. Psilocybin induced anxiolytic-, but not antidepressant-like, which were fully blocked by stress in males, but only partially so in females. Lastly, we assessed the acute stress-psilocybin interaction on plasma corticosterone levels in a separate cohort of mice, treated as above. Both stress and psilocybin independently increased corticosterone levels, without additive or interactive effects being observed for either sex. Our data reveals the role of sex and peri-acute negative experiences in the acute and post-acute actions of psilocybin. These findings underline the importance of non-pharmacological factors, such as the quality of the psychedelic experience, in the mood-altering effects of psychedelics, holding significant for both their therapeutic and recreational use.

Evaluating the value and risks of psychedelics for psychiatric medicine: a clinical perspective

INTRODUCTION

After a long period of obscurantism, a possible role of psychedelics in clinical practice has progressively become a tangible perspective during the last two decades. However, the resounding enthusiasm linked to such 'psychedelic renaissance' runs the risk to unduly minimize the possible hazards associated with these compounds, while expanding their alleged benefits to improbable panacea-like proportions. In order to avoid mystifying or demonizing the properties of 5-HT2a agonists on emotional grounds, this subject requires a strictly unprejudiced and cautious approach to the evidence.

AREAS COVERED

In this article, the authors attempted to comprehensively analyze the available literature to provide a balanced overview of the possible benefits of psychedelics in healthcare, taking into account their potential risks.

EXPERT OPINION

To date, psychedelics have shown a therapeutic potential in a wide range of conditions, with a seemingly limited risk of inducing adverse reactions, including abuse and dependence, when administered in a controlled environment by specialized personnel. In any case, although several questions remain unanswered before drawing firm conclusions, further studies are needed to establish which conditions and subjects could benefit from psychedelics and which patients bear the greater risk of adversities.

Emerging medications and pharmacological treatment approaches for substance use disorders

Medications to treat substance use disorders remain suboptimal or, in the case of stimulants and cannabis, non-existent. Many factors have contributed to this paucity, including the biological complexity of addiction, regulatory challenges, and a historical lack of enthusiasm among pharmaceutical companies to commit resources to this disease space. Despite these headwinds, the recent opioid crisis has highlighted the devastating consequences of SUDs for both individuals and society, stimulating urgent efforts to identify novel treatment approaches. In addition, several neurobiological systems have been recently implicated in unique aspects of drug reward, opening the door to candidate medications with novel mechanisms of action. Here, we provide an overview of efforts to target several of these new systems, with a focus on those that are the subject of ongoing clinical trials as well as being areas of interest among the authors' research groups (MHJ, MTB, NAE). Specifically, we discuss new classes of medications targeting the serotonin 2 A receptor (i.e., psychedelics), glucagon-like peptide 1 receptor, cannabidiol, dynorphin/kappa opioid receptor, orexin/hypocretin, and oxytocin receptor systems, as well as emergent approaches for modulating the more canonical dopaminergic system via agonist therapies for stimulant use disorders. Collectively, innovations in this space give reason for optimism for an improved therapeutic landscape for substance use disorders in the near future.

From taboo to treatment: The emergence of psychedelics in the management of pain and opioid use disorder

The rise of psychedelics in contemporary medicine has sparked interest in their potential therapeutic applications. While traditionally associated with countercultural movements and recreational use, recent research has shed light on the potential benefits of psychedelics in various mental health conditions. In this review, we explore the possible role of psychedelics in the management of chronic pain and opioid use disorder (OUD), 2 critical areas in need of innovative treatment options. Pain control remains a significant clinical challenge, particularly for individuals with OUD and those who receive long-term opioid therapy who develop marked tolerance to opioid-induced analgesia. Despite the magnitude of this problem, there is a scarcity of controlled studies investigating pain management alternatives for these populations. Drawing from preclinical and human evidence, we highlight the potential of psychedelics to act on shared neurobiological substrates of chronic pain and OUD, potentially reversing pain- and opioid-induced neuroadaptations, such as central sensitization. We elaborate on the multifaceted dimensions of the pain experience (sensory, affective and cognitive) and their intersections that overlap with opioid-related phenomena (opioid craving and withdrawal), hypothesizing how these processes can be modulated by psychedelics. After summarizing the available clinical research, we propose mechanistic insights and methodological considerations for the design of future translational studies and clinical trials, building on a shared clinical and neurobiological understanding of chronic pain and OUD. Our intention is to provide timely perspectives that accelerate the development and exploration of novel therapeutics for chronic pain and OUD amidst the escalating opioid crisis.

Psilocybin as a novel treatment for chronic pain

Psychedelic drugs are under active consideration for clinical use and have generated significant interest for their potential as anti-nociceptive treatments for chronic pain, and for addressing conditions like depression, frequently co-morbid with pain. This review primarily explores the utility of preclinical animal models in investigating the potential of psilocybin as an anti-nociceptive agent. Initial studies involving psilocybin in animal models of neuropathic and inflammatory pain are summarised, alongside areas where further research is needed. The potential mechanisms of action, including targeting serotonergic pathways through the activation of 5-HT2A receptors at both spinal and central levels, as well as neuroplastic actions that improve functional connectivity in brain regions involved in chronic pain, are considered. Current clinical aspects and the translational potential of psilocybin from animal models to chronic pain patients are reviewed. Also discussed is psilocybin's profile as an ideal anti-nociceptive agent, with a wide range of effects against chronic pain and its associated inflammatory or emotional components.

Psilocin, the Psychoactive Metabolite of Psilocybin, Modulates Select Neuroimmune Functions of Microglial Cells in a 5-HT2 Receptor-Dependent Manner

Neuroinflammation that is caused by microglia, the main immune cells of the brain, contributes to neurodegenerative diseases. Psychedelics, including psilocybin and lysergic acid diethylamide (LSD), possess certain anti-inflammatory properties and, therefore, should be considered as drug candidates for treating neuroinflammatory pathologies. When ingested, psilocybin is rapidly dephosphorylated to yield psilocin, which crosses the blood-brain barrier and exerts psychotropic activity by interacting with the 5-hydroxytryptamine 2A receptors (5-HT2ARs) on neurons. Since microglia express all three 5-HT2R isoforms, we hypothesized that, by interacting with these receptors, psilocin beneficially modulates select neuroimmune functions of microglia. We used microglia-like cell lines to demonstrate that psilocin, at non-toxic concentrations, did not affect the secretion of tumor necrosis factor (TNF) by immune-stimulated microglial cells, but significantly inhibited their phagocytic activity, the release of reactive oxygen species (ROS), and nitric oxide (NO) production. The inhibitory activity of psilocin on the latter two functions was similar to that of two selective 5-HT2R agonists, namely, 25I-NBOH and Ro60-0175. The role of this subfamily of receptors was further demonstrated by the application of 5-HT2R antagonists cyproheptadine and risperidone. Psilocin should be considered a novel drug candidate that might be effective in treating neuroimmune disorders, such as neurodegenerative diseases, where reactive microglia are significant contributors.

Chemistry/structural biology of psychedelic drugs and their receptor(s)

This brief review highlights some of the structure-activity relationships of classic serotonergic psychedelics. In particular, we discuss structural features of three chemotypes: phenethylamines, ergolines and certain tryptamines, which possess psychedelic activity in humans. Where they are known, we point out the underlying molecular mechanisms utilized by each of the three chemotypes of psychedelic molecules. With a focus on the 5-HT2A receptor subtype, a G-protein coupled receptor known to be the primary target of psychedelics, we refer to several X-ray and cryoEM structures, with a variety of ligands bound, to illustrate the underlying atomistic basis for some of the known pharmacological observations of psychedelic drug actions.

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.

The immunomodulatory effects of classical psychedelics: A systematic review of preclinical studies

Emerging evidence suggests that classical psychedelics possess immunomodulatory and anti-inflammatory properties; however, these effects are yet to be well-established. This systematic review aims to provide a timely and comprehensive overview of the immunomodulatory effects of classical psychedelics in preclinical studies. A systematic search was conducted on six databases, including CINAHL, EMBASE, MEDLINE, PsychINFO, Scopus, and Web of Science. Eligible studies targeting classical psychedelics for evaluation of their effects on inflammatory markers and immunomodulation have been included for analysis. Data was extracted from 40 out of 2822 eligible articles, and their risk of bias was assessed using the Systematic Review Center for Laboratory Animal Experimentation (SYRCLE) tool and Quality Assessment Tool for In Vitro Studies (QUIN). Studies examined 2,5-dimethoxy-4-iodoamphetamine (DOI; n = 18); psilocybin (4-PO-DMT; n = 9); N,N-dimethyltryptamine (DMT; n = 8); lysergic acid diethylamide (LSD; n = 6); 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT; n = 3); psilocin (4-HO-DMT; n = 3); and mescaline (n = 2). In 36 studies where inflammatory cytokine levels were measured following psychedelic administration, a decrease in at least one inflammatory cytokine was observed in 29 studies. Immune cell activity was assessed in 10 studies and findings were mixed, with an equal number of studies (n = 5 out of 10) reporting either an increase or decrease in immune cell activity. Classical psychedelics were found to alleviate pre-existing inflammation but promote inflammation when administered under normal physiological conditions. This information is anticipated to inform future clinical trials, exploring classical psychedelics' potential to alleviate inflammation in various pathologies.

Psychotomimetic compensation versus sensitization

It is a paradox that psychotomimetic drugs can relieve symptoms that increase risk of and cooccur with psychosis, such as attention and motivational deficits (e.g., amphetamines), pain (e.g., cannabis) and symptoms of depression (e.g., psychedelics, dissociatives). We introduce the ideas of psychotomimetic compensation and psychotomimetic sensitization to explain this paradox. Psychotomimetic compensation refers to a short-term stressor or drug-induced compensation against stress that is facilitated by engagement of neurotransmitter/modulator systems (endocannabinoid, serotonergic, glutamatergic and dopaminergic) that mediate the effects of common psychotomimetic drugs. Psychotomimetic sensitization occurs after repeated exposure to stress and/or drugs and is evidenced by the gradual intensification and increase of psychotic-like experiences over time. Theoretical and practical implications of this model are discussed.

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.

Evaluation of Cordyceps militaris steroids as anti-inflammatory agents to combat the Covid-19 cytokine storm: a bioinformatics and structure-based drug designing approach

Since the SARS-CoV-2 epidemic, researchers have been working on figuring out ways to tackle multi-organ failure and hyperinflation, which are brought on by a cytokine storm. Angiotensin-converting enzyme 2 (ACE2), a SARS-CoV-2 spike glycoprotein's cellular receptor, is involved in complicated molecular processes that result in hyperinflammation. Cordyceps militaris is one of the traditional Chinese medicines that is used as an immune booster, and it has exhibited efficacy in lowering blood glucose levels, seminal emissions, and infertility. In the current study, we explored the potential of Cordyceps militaris steroids as key agents in managing the anger of cytokine storm in Covid-19 using network ethnopharmacological techniques and structure-based drug designing approaches. The steroids present in Cordyceps militaris were initially screened against the targets involved in inflammatory pathways. The results revealed that out of 16 steroids, 5 may be effective against 17 inflammatory pathways by targeting 11 pathological proteins. Among the five steroids, beta-sitosterol, Cholest-5-en-3β-ol, 3β, and 7α-Dihydroxycholest-5-ene were found to interact with thrombin (F2), an important protein reported to reduce the severity of inflammatory mediators and Cholest-4-en-3-one was found to target Glucocorticoid receptor (NR3C1). The top docked steroid displayed key interactions with both targets, which retained key interactions throughout the 100 ns simulation period. These compounds were also shown high binding free energy scores in water swap studies. Based on obtained results the current study suggests the use of Cordyceps militaris as an add-on therapy that may reduce the progression of inflammatory co-morbidities among patients infected with SARS-CoV-2.Communicated by Ramaswamy H. Sarma.

Effects of congeners of amphetamine on the human heart

Central stimulatory and hallucinogenic drugs of abuse like amphetamine and most congeners of amphetamine can have cardiac harmful effects. These cardiac side effects can lead to morbidities and death. In this paper, we review current knowledge on the direct and indirect effects of these amphetamine congeners on the mammalian heart-more specifically, the isolated human heart muscle preparation. In detail, we address the question of whether and how these drugs affect cardiac contractility and their mechanisms of action. Based on this information, further research areas are defined, and further research efforts are proposed.

Single administration of a psychedelic [(R)-DOI] influences coping strategies to an escapable social stress

Psychedelic compounds have potentially rapid, long-lasting anxiolytic, antidepressive and anti-inflammatory effects. We investigated whether the psychedelic compound (R)-2,5-dimethoxy-4-iodoamphetamine [(R)-DOI], a selective 5-HT2A receptor partial agonist, decreases stress-related behavior in male mice exposed to repeated social aggression. Additionally, we explored the likelihood that these behavioral changes are related to anti-inflammatory properties of [(R)-DOI]. Animals were subjected to the Stress Alternatives Model (SAM), an escapable social stress paradigm in which animals develop reactive coping strategies - remaining in the SAM arena (Stay) with a social aggressor, or dynamically initiated stress coping strategies that involve utilizing the escape holes (Escape) to avoid aggression. Mice expressing these behavioral phenotypes display behaviors like those in other social aggression models that separate animals into stress-vulnerable (as for Stay) or stress-resilient (as for Escape) groups, which have been shown to have distinct inflammatory responses to social stress. These results show that Stay animals have heightened cytokine gene expression, and both Stay and Escape mice exhibit plasma and neural concentrations of the inflammatory cytokine tumor necrosis factor-α (TNFα) compared to unstressed control mice. Additionally, these results suggest that a single administration of (R)-DOI to Stay animals in low doses, can increase stress coping strategies such as increasing attention to the escape route, promoting escape behavior, and reducing freezing during socially aggressive interaction in the SAM. Lower single doses of (R)-DOI, in addition to shifting behavior to suggest anxiolytic effects, also concomitantly reduce plasma and limbic brain levels of the inflammatory cytokine TNFα.

1-(2,5-Dimethoxy-4-iodophenyl)-2-aminopropane (DOI): From an Obscure to Pivotal Member of the DOX Family of Serotonergic Psychedelic Agents - A Review

1-(2,5-Dimethoxy-4-iodophenyl)-2-aminopropane (DOI, or DOX where X = -I) was first synthesized in 1973 in a structure-activity study to explore the effect of various aryl substituents on the then newly identified, and subsequently controlled, hallucinogenic agent 1-(2,5-dimethoxy-4-methylphenyl)-2-aminopropane (DOM, or DOX where X = -CH3). Over time, DOI was found to be a serotonin (5-HT) receptor agonist using various peripheral 5-HT receptor tissue assays and later, following the identification of multiple families of central 5-HT receptors, an agonist at 5-HT2 serotonin receptors in rat and, then, human brain. Today, classical hallucinogens, currently referred to as serotonergic psychedelic agents, are receiving considerable attention for their potential therapeutic application in various neuropsychiatric disorders including treatment-resistant depression. Here, we review, for the first time, the historical and current developments that led to DOI becoming a unique, perhaps a landmark, agent in 5-HT2 receptor research.

Unlocking the healing power of psilocybin: an overview of the role of psilocybin therapy in major depressive disorder, obsessive-compulsive disorder and substance use disorder

Resistance to traditional treatment methods is still a major obstacle in modern psychiatry. As a result, several studies are currently being conducted to find effective alternatives to traditional therapies. One of these alternatives is psilocybin, a psychedelic substance that has been tested in clinical trials as an adjunct to psychotherapy. These studies focus on patients with major depressive disorder (MDD), obsessive-compulsive disorder (OCD) and substance use disorder (SUD), particularly alcohol and nicotine dependence. This article looks at the current understanding of psilocybin, including data from clinical trials conducted, psilocybin's mechanism of action, its safety and the level of risk associated with it.

Study protocol for "Psilocybin in patients with fibromyalgia: brain biomarkers of action"

Background

Chronic pain is a leading cause of disability worldwide. Fibromyalgia is a particularly debilitating form of widespread chronic pain. Fibromyalgia remains poorly understood, and treatment options are limited or moderately effective at best. Here, we present a protocol for a mechanistic study investigating the effects of psychedelic-assisted-therapy in a fibromyalgia population. The principal focus of this trial is the central mechanism(s) of psilocybin-therapy i.e., in the brain and on associated mental schemata, primarily captured by electroencephalography (EEG) recordings of the acute psychedelic state, plus pre and post Magnetic Resonance Imaging (MRI).

Methods

Twenty participants with fibromyalgia will complete 8 study visits over 8 weeks. This will include two dosing sessions where participants will receive psilocybin at least once, with doses varying up to 25mg. Our primary outcomes are 1) Lempel-Ziv complexity (LZc) recorded acutely using EEG, and the 2) the (Brief Experiential Avoidance Questionnaire (BEAQ) measured at baseline and primary endpoint. Secondary outcomes will aim to capture broad aspects of the pain experience and related features through neuroimaging, self-report measures, behavioural paradigms, and qualitative interviews. Pain Symptomatology will be measured using the Brief Pain Inventory Interference Subscale (BPI-IS), physical and mental health-related function will be measured using the 36-Item Short Form Health Survey (SF-36). Further neurobiological investigations will include functional MRI (fMRI) and diffusion tensor imaging (changes from baseline to primary endpoint), and acute changes in pre- vs post-acute spontaneous brain activity - plus event-related potential functional plasticity markers, captured via EEG.

Discussion

The results of this study will provide valuable insight into the brain mechanisms involved in the action of psilocybin-therapy for fibromyalgia with potential implications for the therapeutic action of psychedelic-therapy more broadly. It will also deliver essential data to inform the design of a potential subsequent RCT.

Chronic pain as an emergent property of a complex system and the potential roles of psychedelic therapies

Despite research advances and urgent calls by national and global health organizations, clinical outcomes for millions of people suffering with chronic pain remain poor. We suggest bringing the lens of complexity science to this problem, conceptualizing chronic pain as an emergent property of a complex biopsychosocial system. We frame pain-related physiology, neuroscience, developmental psychology, learning, and epigenetics as components and mini-systems that interact together and with changing socioenvironmental conditions, as an overarching complex system that gives rise to the emergent phenomenon of chronic pain. We postulate that the behavior of complex systems may help to explain persistence of chronic pain despite current treatments. From this perspective, chronic pain may benefit from therapies that can be both disruptive and adaptive at higher orders within the complex system. We explore psychedelic-assisted therapies and how these may overlap with and complement mindfulness-based approaches to this end. Both mindfulness and psychedelic therapies have been shown to have transdiagnostic value, due in part to disruptive effects on rigid cognitive, emotional, and behavioral patterns as well their ability to promote neuroplasticity. Psychedelic therapies may hold unique promise for the management of chronic pain.

Ayahuasca and its major component harmine promote antinociceptive effects in mouse models of acute and chronic pain

ETHNOPHARMACOLOGICAL RELEVANCE

Ayahuasca (AYA) is a psychedelic brew used in religious ceremonies. It is broadly used as a sacred medicine for treating several ailments, including pain of various origins.

AIM OF THE STUDY

To investigate the antinociceptive effects of AYA and its mechanisms in preclinical models of acute and chronic pain in mice, in particular during experimental neuropathy.

MATERIALS AND METHODS

The antinociceptive effects of AYA administered orally were assessed in the following models of pain: formalin test, Complete Freund's Adjuvant (CFA)-induced inflammation, tail flick test, and partial sciatic nerve ligation model of neuropathic pain. Antagonism assays and Fos immunohistochemistry in the brain were performed. AYA-induced toxicity was investigated. AYA was chemically characterized. The antinociceptive effect of harmine, the major component present in AYA, was investigated.

RESULTS

AYA (24-3000 μL/kg) dose-dependently reduced formalin-induced pain-like behaviors and CFA-induced mechanical allodynia but did not affect CFA-induced paw edema or tail flick latency. During experimental neuropathy, single treatments with AYA (24-3000 μL/kg) reduced mechanical allodynia; daily treatments once or twice a day for 14 days promoted consistent and sustained antinociception. The antinociceptive effect of AYA (600 μL/kg) was reverted by bicuculline (1 mg/kg) and methysergide (5 mg/kg), but not by naloxone (5 mg/kg), phaclofen (2 mg/kg), and rimonabant (10 mg/kg), suggesting the roles of GABAA and serotonergic receptors. AYA increased Fos expression in the ventrolateral periaqueductal gray and nucleus raphe magnus after 1 h, but not after 6 h or 14 days of daily treatments. AYA (600 μL/kg) twice a day for 14 days did not alter mice's motor function, spontaneous locomotion, body weight, food and water intake, hematological, biochemical, and histopathological parameters. Harmine (3.5 mg/kg) promoted consistent antinociception during experimental neuropathy.

CONCLUSIONS

AYA promotes consistent antinociceptive effects in different mouse models of pain without inducing detectable toxic effects. Harmine is at least partially accountable for the antinociceptive properties of AYA.

The potential of 5-methoxy-N,N-dimethyltryptamine in the treatment of alcohol use disorder: A first look at therapeutic mechanisms of action

Alcohol use disorder (AUD) remains one of the most prevalent psychiatric disorders worldwide with high economic costs. Current treatment options show modest efficacy and relapse rates are high. Furthermore, there are increases in the treatment gap and few new medications have been approved in the past 20 years. Recently, psychedelic-assisted therapy with psilocybin and lysergic acid diethylamide has garnered significant attention in the treatment of AUD. Yet, they require significant amounts of therapist input due to prolonged subjective effects (~4-12 h) leading to high costs and impeding implementation. Accordingly, there is an increasing interest in the rapid and short-acting psychedelic 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT). This paper offers a first look at potential therapeutic mechanisms for AUD by reviewing the current literature on 5-MeO-DMT. Primarily, 5-MeO-DMT is able to induce mystical experiences and ego-dissolution together with increases in psychological flexibility and mindfulness. This could decrease AUD symptoms through the alleviation of psychiatric mood-related comorbidities consistent with the negative reinforcement and self-medication paradigms. In addition, preliminary evidence indicates that 5-MeO-DMT modulates neural oscillations that might subserve ego-dissolution (increases in gamma), psychological flexibility and mindfulness (increases in theta), and the reorganization of executive control networks (increases in coherence across frequencies) that could improve emotion regulation and inhibition. Finally, animal studies show that 5-MeO-DMT is characterized by neuroplasticity, anti-inflammation, 5-HT2A receptor agonism, and downregulation of metabotropic glutamate receptor 5 with clinical implications for AUD and psychiatric mood-related comorbidities. The paper concludes with several recommendations for future research to establish the purported therapeutic mechanisms of action.

Psychedelics for alzheimer's disease-related dementia: Unveiling therapeutic possibilities and pathways

Psychedelics have traditionally been used for spiritual and recreational purposes, but recent developments in psychotherapy have highlighted their potential as therapeutic agents. These compounds, which act as potent 5-hydroxytryptamine (5HT) agonists, have been recognized for their ability to enhance neural plasticity through the activation of the serotoninergic and glutamatergic systems. However, the implications of these findings for the treatment of neurodegenerative disorders, particularly dementia, have not been fully explored. In recent years, studies have revealed the modulatory and beneficial effects of psychedelics in the context of dementia, specifically Alzheimer's disease (AD)-related dementia, which lacks a definitive cure. Psychedelics such as N,N-dimethyltryptamine (DMT), lysergic acid diethylamide (LSD), and Psilocybin have shown potential in mitigating the effects of this debilitating disease. These compounds not only target neurotransmitter imbalances but also act at the molecular level to modulate signalling pathways in AD, including the brain-derived neurotrophic factor signalling pathway and the subsequent activation of mammalian target of rapamycin and other autophagy regulators. Therefore, the controlled and dose-dependent administration of psychedelics represents a novel therapeutic intervention worth exploring and considering for the development of drugs for the treatment of AD-related dementia. In this article, we critically examined the literature that sheds light on the therapeutic possibilities and pathways of psychedelics for AD-related dementia. While this emerging field of research holds great promise, further studies are necessary to elucidate the long-term safety, efficacy, and optimal treatment protocols. Ultimately, the integration of psychedelics into the current treatment paradigm may provide a transformative approach for addressing the unmet needs of individuals living with AD-related dementia and their caregivers.

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

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

Scoping Review: The Role of Psychedelics in the Management of Chronic Pain

Introduction

Amid a lack of effective chronic pain treatments, psychedelics have gained attention as a potential solution, although their Schedule 1 classification poses challenges. Psychedelics, such as lysergic acid diethylamide (LSD) and psilocybin, have gained popularity as alternatives and adjuncts for chronic pain treatment. Studies suggest that they may modulate pain processing through agonism primarily at the serotonin receptor, 5-HT2A. One of the first of its nature, we present an artificial intelligence (AI)-powered scoping review primarily focusing on evaluating psychedelics for chronic pain conditions such as cluster headache, phantom limb pain, and fibromyalgia.

Methods

In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, we used an AI-powered comprehensive search strategy utilizing the ChatGPT4.0 Bing chat to search Medline, Embase, Cochrane, and Google Scholar for articles addressing chronic pain. The query was performed on June 1, 2023, focusing on psychedelics for chronic, non-cancer pain including headache disorders. Inclusion criteria were English-only, peer-reviewed articles involving human participants >18 years, focusing on chronic pain conditions (eg, phantom limb pain and cluster headache), using LSD, 2.5-dimethoxy-4-bromophenethylamine (2C-B), N, N-dimethyltryptamine (DMT), psilocybin, or mescaline. Exclusion criteria were reviews, editorials, and opinion articles and studies focusing on tetrahydrocannabinol/cannabis and/or ketamine.

Results

A total of 186 unique database entries were retrieved, of which nine studies were included in the scoping review. These included four case reports/series, an open-label study, a cohort study, two online surveys, and a randomized, double-blind, placebo-controlled trial. They comprised three studies addressing phantom limb pain, four addressing cluster headaches, and two addressing fibromyalgia, spinal cord injury, complex regional pain syndrome, and lumbar radiculopathy.

Conclusion

Psychedelics may have potential in alleviating pain symptoms secondary to a multitude of chronic pain conditions. However, further randomized, double-blind, placebo-controlled trials are needed to further explore and evaluate the role of psychedelics in chronic, non-cancer pain.

Psychedelic Therapy: A Primer for Primary Care Clinicians-Psilocybin

BACKGROUND

The primary psychoactive drug in magic mushrooms, psilocybin, induces profound alterations in consciousness through the 5-HT2A receptor. This review consolidates current research findings to elucidate the pharmacology, safety profile, and clinical applications of psilocybin.

AREAS OF UNCERTAINTY

Despite initial concerns that psilocybin could cause psychosis, contemporary research has demonstrated that psilocybin is generally safe. The most common adverse effects are nausea and headache, yet both tend to be transient. Serious adverse events can generally be avoided in controlled settings such as clinical trials. However, in the largest clinical trial to date, there were a total of 7 reported cases of suicidal ideation, up to 12 weeks after receiving a single 25 mg dose of psilocybin. That being said, all 7 cases did not respond to the treatment. Although selective serotonin reuptake inhibitors may blunt the hallucinogenic qualities of psilocybin, preliminary research suggests that they may enhance its antidepressant effects.

THERAPEUTIC ADVANCES

In clinical trials, psilocybin has shown promise for treating major depressive disorder and treatment-resistant depression. Initial studies indicated that 42%-57% of patients underwent remission after psilocybin-assisted therapy, which suggests that psilocybin is more effective than existing antidepressant medications. Clinical data have also demonstrated that psilocybin can manage substance use disorders and end-of-life anxiety with clinical outcomes that are sustained for months and sometimes years after 1 or 2 doses.

LIMITATIONS

However, larger Phase II trials with more than 100 depressed participants have shown a much smaller remission rate of 25%-29%, though these studies still observed that psilocybin causes a significant reduction in depressive symptoms.

CONCLUSIONS

Aside from ketamine, psilocybin is the most clinically well-researched psychedelic drug, with trials that have enrolled hundreds of participants and multiple therapeutic applications. Phase III trials will determine whether psilocybin lives up to the promise that it showed in previous clinical trials.

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.

Serotonin-2 Receptor Agonists Produce Anti-inflammatory Effects through Functionally Selective Mechanisms That Involve the Suppression of Disease-Induced Arginase 1 Expression

Functional selectivity in the context of serotonin 2A (5-HT2A) receptor agonists is often described as differences psychedelic compounds have in the activation of Gq vs β-arrestin signaling in the brain and how that may relate to inducing psychoactive and hallucinatory properties with respect to each other. However, the presence of 5-HT2A receptors throughout the body in several cell types, including endothelial, endocrine, and immune-related tissues, suggests that functional selectivity may exist in the periphery as well. Here, we examine functional selectivity between two 5-HT2A receptor agonists of the phenylalkylamine class: (R)-2,5-dimethoxy-4-iodoamphetamine [(R)-DOI] and (R)-2,5-dimethoxy-4-trifluoromethylamphetamine [(R)-DOTFM]. Despite comparable in vitro activity at the 5-HT2A receptor as well as similar behavioral potency, (R)-DOTFM does not exhibit an ability to prevent inflammation or elevated airway hyperresponsiveness (AHR) in an acute murine ovalbumin-induced asthma model as does (R)-DOI. Furthermore, there are distinct differences between protein expression and inflammatory-related gene expression in pulmonary tissues between the two compounds. Using (R)-DOI and (R)-DOTFM as tools, we further elucidated the anti-inflammatory mechanisms underlying the powerful anti-inflammatory effects of certain psychedelics and identified key mechanistic components of the anti-inflammatory effects of psychedelics, including suppression of arginase 1 expression.

Targeting inflammatory signaling in obsessive compulsive disorder: a promising approach

Obsessive-compulsive disorder (OCD) is a neuropsychiatric disorder. Approximately, around 2% to 3% percent of the general population experience symptoms of OCD over the course of their lifetime. OCD can lead to economic burden, poor quality of life, and disability. The characteristic features exhibited generally in OCD are continuous intrusive thoughts and periodic ritualized behaviours. Variations in genes, pathological function of Cortico-Striato-Thalamo-Cortical (CSTC) circuits and dysregulation in the synaptic conduction have been the major factors involved in the pathological progression of OCD. However, the basic mechanisms still largely unknown. Current therapies for OCD largely target monoaminergic neurotransmitters (NTs) in specific dopaminergic and serotonergic circuits. However, such therapies have limited efficacy and tolerability. Drug resistance has been one of the important reasons reported to critically influence the effectiveness of the available drugs. Inflammation has been a crucial factor which is believed to have a significant importance in OCD progression. A significant number of proinflammatory cytokines have been reportedly amplified in patients with OCD. Mechanisms of drug treatment involve attenuation of the symptoms via modulation of inflammatory signalling pathways, modification in brain structure, and synaptic plasticity. Hence, targeting inflammatory signaling may be considered as a suitable approach in the treatment of OCD. The present review focuses mainly on the significant findings from the animal and human studies conducted in this area, that targets inflammatory signaling in neurological conditions. In addition, it also focusses on the therapeutic approaches that target OCD via modification of the inflammatory signaling pathways.

Potential analgesic effects of psychedelics on select chronic pain conditions: A survey study

BACKGROUND

Chronic pain is a major cause of suffering and disability and is often associated with psychiatric complications. Current treatments carry the risk of severe side effects and may lead to limited or no relief at all in a relevant portion of this patient population. Preliminary evidence suggests that classical psychedelics (e.g. LSD and psilocybin) may have analgesic effects in healthy volunteers, and in certain chronic pain conditions and observational studies reveal that they are used in naturalistic settings as a means to manage pain.

METHODS

In order to gain insight on the effectiveness of such compounds in chronic pain conditions, we set up a survey addressed to chronic pain patients inquiring about psychedelic use and the relief levels achieved with both conventional treatments, full psychedelic doses and microdoses. We analysed data related to five conditions selected based on diagnostic homogeneity within each of them: fibromyalgia, arthritis, migraine, tension-type headache and sciatica.

RESULTS

Except for sciatica, volunteers reported that psychedelics led to better pain relief compared to conventional medication in all examined conditions. More specifically, full doses performed better than conventional medication. Microdoses led to significantly better relief compared to conventional medication in migraines and achieved comparable relief in the remaining three categories. Implications for future research are discussed.

CONCLUSIONS

Full doses and microdoses may hold value in the treatment of some specific chronic pain conditions.

SIGNIFICANCE

Psychedelic substances are receiving increasing attention from the scientific literature because of evidence showing beneficial effects on several measures related to mental health in clinical samples and healthy volunteers samples. Previous evidence suggests that people suffering from chronic pain are using psychedelics to seek relief and the present paper presents the results of a survey study investigating their use and analgesic effects among individuals suffering from fibromyalgia, arthritis, migraine, tension-type headache and sciatica.

Psilocybin and Eugenol Reduce Inflammation in Human 3D EpiIntestinal Tissue

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

The potential of psychedelics for the treatment of Alzheimer's disease and related dementias

Alzheimer's Disease (AD) is a currently incurable but increasingly prevalent fatal and progressive neurodegenerative disease, demanding consideration of therapeutically relevant natural products and their synthetic analogues. This paper reviews evidence for effectiveness of natural and synthetic psychedelics in the treatment of AD causes and symptoms. The plastogenic effects of serotonergic psychedelics illustrate that they have efficacy for addressing multiple facets of AD pathology. We review findings illustrating neuroplasticity mechanisms of classic (serotonergic) and non-classic psychedelics that indicate their potential as treatments for AD and related dementias. Classic psychedelics modulate glutamatergic neurotransmission and stimulate synaptic and network remodeling that facilitates synaptic, structural and behavioral plasticity. Up-regulation of neurotrophic factors enable psychedelics to promote neuronal survival and glutamate-driven neuroplasticity. Muscimol modulation of GABAAR reduces Aβ-induced neurotoxicity and psychedelic Sig-1R agonists provide protective roles in Aβ toxicity. Classic psychedelics also activate mTOR intracellular effector pathways in brain regions that show atrophy in AD. The potential of psychedelics to treat AD involves their ability to induce structural and functional neural plasticity in brain circuits and slow or reverse brain atrophy. Psychedelics stimulate neurotrophic pathways, increase neurogenesis and produce long-lasting neural changes through rewiring pathological neurocircuitry. Psychedelic effects on 5-HT receptor target genes and induction of synaptic, structural, and functional changes in neurons and networks enable them to promote and enhance brain functional connectivity and address diverse mechanisms underlying degenerative neurological disorders. These findings provide a rationale for immediate investigation of psychedelics as treatments for AD patients.

Psilocybin induces acute and persisting alterations in immune status in healthy volunteers: An experimental, placebo-controlled study

Patients characterized by stress-related disorders such as depression display elevated circulating concentrations of pro-inflammatory cytokines and a hyperactive HPA axis. Psychedelics are demonstrating promising results in treatment of such disorders, however the mechanisms of their therapeutic effects are still unknown. To date the evidence of acute and persisting effects of psychedelics on immune functioning, HPA axis activity in response to stress, and associated psychological outcomes is preliminary. To address this, we conducted a placebo-controlled, parallel group design comprising of 60 healthy participants who received either placebo (n = 30) or 0.17 mg/kg psilocybin (n = 30). Blood samples were taken to assess acute and persisting (7 day) changes in immune status. Seven days' post-administration, participants in each treatment group were further subdivided: 15 underwent a stress induction protocol, and 15 underwent a control protocol. Ultra-high field (7-Tesla) magnetic resonance spectroscopy was used to assess whether acute changes in glutamate or glial activity were associated with changes in immune functioning. Finally, questionnaires assessed persisting self-report changes in mood and social behavior. Psilocybin immediately reduced concentrations of the pro-inflammatory cytokine tumor necrosis factor-α (TNF-α), while other inflammatory markers (interleukin (IL)- 1β, IL-6, and C-reactive protein (CRP)) remained unchanged. Seven days later, TNF-α concentrations returned to baseline, while IL-6 and CRP concentrations were persistently reduced in the psilocybin group. Changes in the immune profile were related to acute neurometabolic activity as acute reductions in TNF-α were linked to lower concentrations of glutamate in the hippocampus. Additionally, the more of a reduction in IL-6 and CRP seven days after psilocybin, the more persisting positive mood and social effects participants reported. Regarding the stress response, after a psychosocial stressor, psilocybin did not significantly alter the stress response. Results are discussed in regards to the psychological and therapeutic effects of psilocybin demonstrated in ongoing patient trials.

Three Cases of Reported Improvement in Microsmia and Anosmia Following Naturalistic Use of Psilocybin and LSD

Cultural awareness of anosmia and microsmia has recently increased due to their association with COVID-19, though treatment for these conditions is limited. A growing body of online media claims that individuals have noticed improvement in anosmia and microsmia following classic psychedelic use. We report what we believe to be the first three cases recorded in the academic literature of improvement in olfactory impairment after psychedelic use. In the first case, a man who developed microsmia after a respiratory infection experienced improvement in smell after the use of 6 g of psilocybin containing mushrooms. In the second case, a woman with anosmia since childhood reported olfactory improvement after ingestion of 100 µg of lysergic acid diethylamide (LSD). In the third case, a woman with COVID-19-related anosmia reported olfactory improvement after microdosing 0.1 g of psilocybin mushrooms three times. Following a discussion of these cases, we explore potential mechanisms for psychedelic-facilitated improvement in olfactory impairment, including serotonergic effects, increased neuroplasticity, and anti-inflammatory effects. Given the need for novel treatments for olfactory dysfunction, increasing reports describing improvement in these conditions following psychedelic use and potential biological plausibility, we believe that the possible therapeutic benefits of psychedelics for these conditions deserve further investigation.

A Comprehensive Review of the Current Status of the Cellular Neurobiology of Psychedelics

Psychedelic substances have gained significant attention in recent years for their potential therapeutic effects on various psychiatric disorders. This review delves into the intricate cellular neurobiology of psychedelics, emphasizing their potential therapeutic applications in addressing the global burden of mental illness. It focuses on contemporary research into the pharmacological and molecular mechanisms underlying these substances, particularly the role of 5-HT2A receptor signaling and the promotion of plasticity through the TrkB-BDNF pathway. The review also discusses how psychedelics affect various receptors and pathways and explores their potential as anti-inflammatory agents. Overall, this research represents a significant development in biomedical sciences with the potential to transform mental health treatments.

Bedside to bench: the outlook for psychedelic research

There has recently been a resurgence of interest in psychedelic compounds based on studies demonstrating their potential therapeutic applications in treating post-traumatic stress disorder, substance abuse disorders, and treatment-resistant depression. Despite promising efficacy observed in some clinical trials, the full range of biological effects and mechanism(s) of action of these compounds have yet to be fully established. Indeed, most studies to date have focused on assessing the psychological mechanisms of psychedelics, often neglecting the non-psychological modes of action. However, it is important to understand that psychedelics may mediate their therapeutic effects through multi-faceted mechanisms, such as the modulation of brain network activity, neuronal plasticity, neuroendocrine function, glial cell regulation, epigenetic processes, and the gut-brain axis. This review provides a framework supporting the implementation of a multi-faceted approach, incorporating in silico, in vitro and in vivo modeling, to aid in the comprehensive understanding of the physiological effects of psychedelics and their potential for clinical application beyond the treatment of psychiatric disorders. We also provide an overview of the literature supporting the potential utility of psychedelics for the treatment of brain injury (e.g., stroke and traumatic brain injury), neurodegenerative diseases (e.g., Parkinson's and Alzheimer's diseases), and gut-brain axis dysfunction associated with psychiatric disorders (e.g., generalized anxiety disorder and major depressive disorder). To move the field forward, we outline advantageous experimental frameworks to explore these and other novel applications for psychedelics.

Exploring the Potential Utility of Psychedelic Therapy for Patients With Amyotrophic Lateral Sclerosis

Background: Amyotrophic lateral sclerosis (ALS) is an aggressive, terminal neurodegenerative disease that causes death of motor neurons and has an average survival time of 3-4 years. ALS is the most common motor neuron degenerative disease and is increasing in prevalence. There is a pressing need for more effective ALS treatments as available pharmacotherapies do not reverse disease progression or provide substantial clinical benefit. Furthermore, despite psychological distress being highly prevalent in ALS patients, psychological treatments remain understudied. Psychedelics (i.e., serotonergic psychedelics and related compounds like ketamine) have seen a resurgence of research into therapeutic applications for treating a multitude of neuropsychiatric conditions, including psychiatric and existential distress in life-threatening illnesses. Methods: We conducted a narrative review to examine the potential of psychedelic assisted-psychotherapy (PAP) to alleviate psychiatric and psychospiritual distress in ALS. We also discussed the safety of using psychedelics in this population and proposed putative neurobiological mechanisms that may therapeutically intervene on ALS neuropathology. Results: PAP has the potential to treat psychological dimensions and may also intervene on neuropathological dimensions of ALS. Robust improvements in psychiatric and psychospiritual distress from PAP in other populations provide a strong rationale for utilizing this therapy to treat ALS-related psychiatric and existential distress. Furthermore, relevant neuroprotective properties of psychedelics warrant future preclinical trials to investigate this area in ALS models. Conclusion: PAP has the potential to serve as an effective treatment in ALS. Given the lack of effective treatment options, researchers should rigorously explore this therapy for ALS in future trials.

Psychoactive substances 25H-NBOMe and 25H-NBOH induce antidepressant-like behavior in male rats

Ring-substituted phenethylamines are believed to induce psychedelic effects primarily by interacting with 5-hydroxytryptamine 2 (5-HT2A) receptors in the brain. We assessed the effect of the psychedelic substances 25H-NBOMe and 25H-NBOH on the depressive-like behavior of male adult rats. Naive Wistar rats were divided into groups to assess the effects of different doses (0.1 mg/kg, 1 mg/kg, and 3 mg/kg) of 25H-NBOMe and 25H-NBOH. The substances were administered intraperitoneally and the hallucinogenic properties were evaluated using the head twitch response test (HTR). Additionally, we assessed their locomotor activity in the open field test (OFT) and depressive-like behavior in the forced swimming test (FST). Our data demonstrated that all doses of synthetic psychedelic substances evaluated exhibited hallucinogenic effects. Interestingly, we observed that both 25H-NBOMe and 25H-NBOH produced a significantly greater motivation to escape in the FST, compared to the control group. Furthermore, we found no significant differences in locomotor activity during the OFT, except for the dose of 3 mg/kg, which induced a reduction in locomotion. This study provides new insights into a potential psychedelic substance, specifically by demonstrating the previously unknown antidepressant properties of a single dose of both 25H-NBOMe and 25H-NBOH. These findings contribute to the ongoing progress of experimental psychiatry toward developing safe and effective clinical practices in the field of psychedelics research.

Psychedelics for treatment resistant depression: are they game changers?

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Neuroimaging in psychedelic drug development: past, present, and future

Psychedelic therapy (PT) is an emerging paradigm with great transdiagnostic potential for treating psychiatric disorders, including depression, addiction, post-traumatic stress disorder, and potentially others. 'Classic' serotonergic psychedelics, such as psilocybin and lysergic acid diethylamide (LSD), which have a key locus of action at the 5-HT2A receptor, form the main focus of this movement, but substances including ketamine, 3,4-Methylenedioxymethamphetamine (MDMA) and ibogaine also hold promise. The modern phase of development of these treatment modalities in the early 21st century has occurred concurrently with the wider use of advanced human neuroscientific research methods; principally neuroimaging. This can potentially enable assessment of drug and therapy brain effects with greater precision and quantification than any previous novel development in psychiatric pharmacology. We outline the major trends in existing data and suggest the modern development of PT has benefitted greatly from the use of neuroimaging. Important gaps in existing knowledge are identified, namely: the relationship between acute drug effects and longer-term (clinically-relevant) effects, the precise characterisation of effects at the 5-HT2A receptor and relationships with functional/clinical effects, and the possible impact of these compounds on neuroplasticity. A road-map for future research is laid out, outlining clinical studies which will directly address these three questions, principally using combined Positron Emission Tomography (PET) and Magnetic Resonance Imaging (MRI) methods, plus other adjunct techniques. Multimodal (PET/MRI) studies using modern PET techniques such as the 5-HT2A-selective ligand [11 C]Cimbi-36 (and other ligands sensitive to neuroplasticity changes) alongside MRI measures of brain function would provide a 'molecular-functional-clinical bridge' in understanding. Such results would help to resolve some of these questions and provide a firmer foundation for the ongoing development of PT.

Anti-Inflammatory Effects of Serotonin Receptor and Transient Receptor Potential Channel Ligands in Human Small Intestinal Epithelial Cells

Intestinal inflammation and dysbiosis can lead to inflammatory bowel diseases (IBD) and systemic inflammation, affecting multiple organs. Developing novel anti-inflammatory therapeutics is crucial for preventing IBD progression. Serotonin receptor type 2A (5-HT2A) ligands, including psilocybin (Psi), 4-Acetoxy-N,N-dimethyltryptamine (4-AcO-DMT), and ketanserin (Ket), along with transient receptor potential (TRP) channel ligands like capsaicin (Cap), curcumin (Cur), and eugenol (Eug), show promise as anti-inflammatory agents. In this study, we investigated the cytotoxic and anti-inflammatory effects of Psi, 4-AcO-DMT, Ket, Cap, Cur, and Eug on human small intestinal epithelial cells (HSEIC). HSEIC were exposed to tumor necrosis factor (TNF)-α and interferon (IFN)-γ for 24 h to induce an inflammatory response, followed by treatment with each compound at varying doses (0-800 μM) for 24 to 96 h. The cytotoxicity was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and protein expression by Western blot (WB) analysis. As single treatments, Psi (40 μM), Cur (0.5 μM), and Eug (50 μM) significantly reduced COX-2 levels without cytotoxic effects. When combined, Psi (40 μM) and Cur (0.5 μM) exhibited synergy, resulting in a substantial decrease in COX-2 protein levels (-28× fold change), although the reduction in IL-6 was less pronounced (-1.6× fold change). Psi (20 μM) and Eug (25 μM) demonstrated the most favorable outcomes, with significant decreases in COX-2 (-19× fold change) and IL-6 (-10× fold change) protein levels. Moreover, the combination of Psi and Eug did not induce cytotoxic effects in vitro at any tested doses. This study is the first to explore the anti-inflammatory potential of psilocybin and 4-AcO-DMT in the intestines while highlighting the potential for synergy between the 5-HT2A and TRP channel ligands, specifically Psi and Eug, in alleviating the TNF-α/IFN-γ-induced inflammatory response in HSEIC. Further investigations should evaluate if the Psi and Eug combination has the therapeutic potential to treat IBD in vivo.

Developing non-opioid therapeutics to alleviate pain among persons with opioid use disorder: a review of the human evidence

The opioid crisis remains a major public health concern, causing significant morbidity and mortality worldwide. Pain is frequently observed among individuals with opioid use disorder (OUD), and the current opioid agonist therapies (OAT) have limited efficacy in addressing the pain needs of this population. We reviewed the most promising non-opioid analgesic therapies for opioid-dependent individuals synthesising data from randomised controlled trials in the Medline database from December 2022 to March 2023. Ketamine, gabapentin, serotoninergic antidepressants, and GABAergic drugs were found to be the most extensively studied non-opioid analgesics with positive results. Additionally, we explored the potential of cannabinoids, glial activation inhibitors, psychedelics, cholecystokinin antagonists, alpha-2 adrenergic agonists, and cholinergic drugs. Methodological improvements are required to advance the development of novel analgesic strategies and establish their safety profile for opioid-dependent populations. We highlight the need for greater integration of experimental pain methods and abuse liability assessments, more granular assessments of prior opioid exposure, greater uniformity of pain types within study samples, and a particular focus on individuals with OUD receiving OAT. Finally, future research should investigate pharmacokinetic interactions between OAT and various non-opioid analgesics and perform reverse translation basic experiments, particularly with methadone and buprenorphine, which remain the standard OUD treatment.

Microbiome: The Next Frontier in Psychedelic Renaissance

The psychedelic renaissance has reignited interest in the therapeutic potential of psychedelics for mental health and well-being. An emerging area of interest is the potential modulation of psychedelic effects by the gut microbiome-the ecosystem of microorganisms in our digestive tract. This review explores the intersection of the gut microbiome and psychedelic therapy, underlining potential implications for personalized medicine and mental health. We delve into the current understanding of the gut-brain axis, its influence on mood, cognition, and behavior, and how the microbiome may affect the metabolism and bioavailability of psychedelic substances. We also discuss the role of microbiome variations in shaping individual responses to psychedelics, along with potential risks and benefits. Moreover, we consider the prospect of microbiome-targeted interventions as a fresh approach to boost or modulate psychedelic therapy's effectiveness. By integrating insights from the fields of psychopharmacology, microbiology, and neuroscience, our objective is to advance knowledge about the intricate relationship between the microbiome and psychedelic substances, thereby paving the way for novel strategies to optimize mental health outcomes amid the ongoing psychedelic renaissance.

Adapting psychedelic medicine for headache and chronic pain disorders

INTRODUCTION

While the majority of current research and development surrounds depression, demoralization, and substance use disorders, there are numerous reports of psychedelics having beneficial effects in other branches of medicine, including for headache disorders and chronic pain.

AREAS COVERED

This perspective reviews conventional forms of treatment for headache and other chronic pain disorders and describes historical, recent, and ongoing investigations of the therapeutic effects of psychedelics in these disorders. The first two clinical trials of psilocybin in headache disorders and recent case reports of psilocybin mushroom self-administration in chronic pain patients are described. This perspective highlights several factors related to the application of psychedelics in chronic pain disorders, comparing this with the standard psychedelic-assisted psychotherapy model of treatment.

EXPERT OPINION

When faced with a more constricted view of psychedelic medicine that features larger doses, underscores subjective effects in the mediation of therapeutic outcomes, and requires adjunctive psychotherapy to ensure safety and efficacy, the application of psychedelics in headache and chronic pain disorders may face challenges. It will be important to allow for flexibility and adaptation in protocols to evaluate different treatment paradigms, mechanisms of action, and the range of pharmacologic and extra-pharmacologic factors that affect psychedelic treatment outcomes.

Psychedelics reopen the social reward learning critical period

Psychedelics are a broad class of drugs defined by their ability to induce an altered state of consciousness1,2. These drugs have been used for millennia in both spiritual and medicinal contexts, and a number of recent clinical successes have spurred a renewed interest in developing psychedelic therapies3-9. Nevertheless, a unifying mechanism that can account for these shared phenomenological and therapeutic properties remains unknown. Here we demonstrate in mice that the ability to reopen the social reward learning critical period is a shared property across psychedelic drugs. Notably, the time course of critical period reopening is proportional to the duration of acute subjective effects reported in humans. Furthermore, the ability to reinstate social reward learning in adulthood is paralleled by metaplastic restoration of oxytocin-mediated long-term depression in the nucleus accumbens. Finally, identification of differentially expressed genes in the 'open state' versus the 'closed state' provides evidence that reorganization of the extracellular matrix is a common downstream mechanism underlying psychedelic drug-mediated critical period reopening. Together these results have important implications for the implementation of psychedelics in clinical practice, as well as the design of novel compounds for the treatment of neuropsychiatric disease.

Interval delivery of 5HT2A agonists using multilayered polymer films

There is an urgent unmet medical need to develop therapeutic options for the ~50% of depression patients suffering from treatment-resistant depression, which is difficult to treat with existing psycho- and pharmaco-therapeutic options. Classical psychedelics, such as the 5HT2A agonists, have re-emerged as a treatment paradigm for depression. Recent clinical trials highlight the potential effectiveness of 5HT2A agonists to improve mood and psychotherapeutic growth in treatment-resistant depression patients, even in those who have failed a median of four previous medications in their lifetime. Moreover, microdosing could be a promising way to achieve long-term alleviation of depression symptoms without a hallucinogenic experience. However, there are a gamut of practical barriers that stymie further investigation of microdosing 5HT2A agonists, including: low compliance with the complicated dosing regimen, high risk of diversion of controlled substances, and difficulty and cost administering the long-term treatment regimens in controlled settings. Here, we developed a drug delivery system composed of multilayered cellulose acetate phthalate (CAP)/Pluronic F-127 (P) films for the encapsulation and interval delivery of 5HT2A agonists from a fully biodegradable and biocompatible implant. CAPP film composition, thickness, and layering strategies were optimized, and we demonstrated three distinct pulses from the multilayered CAPP films in vitro. Additionally, the pharmacokinetics and biodistribution of the 5HT2A agonist 2,5-Dimethoxy-4-iodoamphetamine (DOI) were quantified following the subcutaneous implantation of DOI-loaded single and multilayered CAPP films. Our results demonstrate, for the first time, the interval delivery of psychedelics from an implantable drug delivery system and open the door to future studies into the therapeutic potential of psychedelic delivery.

Effects of serotonergic psychedelics on mitochondria: Transdiagnostic implications for mitochondria-related pathologies

The use of serotonergic psychedelics has gained increasing attention in research, clinical practice and society. Growing evidence suggests fast-acting, transdiagnostic health benefits of these 5-hydroxytryptamine 2A receptor agonists. Here, we provide a brief overview of their benefits for psychological, cardiovascular, metabolic, neurodegenerative, and immunological pathologies. We then review their effect on mitochondria including mitochondrial biogenesis, functioning and transport. Mitochondrial dysregulation is a transdiagnostic mechanism that contributes to the aforementioned pathologies. Hence, we postulate that psychedelic-induced effects on mitochondria partially underlie their transdiagnostic benefits. Based on this assumption, we propose new treatment indications for psychedelics and that the health benefits induced by psychedelics depend on patient-specific mitochondrial dysregulation.

Psilocybin in Palliative Care: An Update

Purpose of Review

This review article summarizes clinically and socially relevant developments over the past five years in the therapeutic use of the classical tryptamine psychedelic substance psilocybin, with respect to the common challenges faced by palliative care patients and their care teams. Psilocybin is available in whole fungal and isolated forms but is not yet approved for therapeutic use in the United States. Using targeted database and gray literature searches, and author recall, key sources were identified, reviewed, and synthesized as to the safety and efficacy of psilocybin in palliative care.

Recent Findings

Life-threatening or life-limiting illnesses and faced by palliative care patients are comorbid with emotional and spiritual distress. Research and field reports reviewed suggest that psilocybin has significant and in some cases, sustained anxiolytic, antidepressant, anti-inflammatory and entheogenic effects with a favorable safety profile. Limitations of the research include the risk for selection bias toward healthy, white, financially privileged individuals, and in general, follow-up timelines too short to appropriately evaluate durability of outcomes in psychospiritual benefits and quality of life.

Summary

While more research is needed for palliative care populations specifically, reasonable inferences can be made regarding the potential for benefit to palliative care patients from psilocybin's demonstrated anxiolytic, antidepressant, anti-inflammatory and entheogenic effects. However, major legal, ethical and financial barriers to access exist for the general population; obstacles which are likely worsened for geriatric and palliative care patients. Empiric treatment and large-scale controlled trials of psilocybin should be conducted to further investigate the findings of the smaller studies reviewed here across a variety of populations, for a greater understanding of therapeutic benefit and clinically relevant safety criteria, and to support thoughtful legalization and medical access.

Are psychedelic medicines the reset for chronic pain? Preliminary findings and research needs

Chronic pain is a leading cause of disability, reduced productivity, healthcare seeking, and a contributor to opioid overdose in the United States. For many people, pain can be satisfactorily managed by existing medicines and comprehensive psychosocial treatments. For others, available treatments are either ineffective or not acceptable due to side effects and concerns about risks. Preliminary evidence suggests that some psychedelics may be effective for certain types of pain and/or improved quality of life with increased functionality and reduced disability and distress in people whose pain may never be completely relieved. Efficacy in these quality-of-life related outcomes would be consistent with the "reset in thinking" about chronic pain management increasingly called for as a more realistic goal for some people than complete elimination of pain. This commentary summarizes the rationale for conducting more basic research and clinical trials to further explore the potential for psychedelics in chronic pain management. And, if shown to be effective, to determine whether the effects of psychedelics are primarily due to direct antinociceptive or anti-inflammatory mechanisms, or via increased tolerability, acceptance, and sense of spirituality, that appear to at least partially mediate the therapeutic effects of psychedelics observed in psychiatric disorders such as major depression. This commentary represents a collaboration of clinical and more basic scientists examining these issues and developing recommendations for research ranging from neuropharmacology to the biopsychosocial treatment factors that appear to be as important in pain management as in depression and other disorders in which psychedelic medicines are under development.