Unifying Theories of Psychedelic Drug Effects

Neural Mechanisms of Resting-State Networks and the Amygdala Underlying the Cognitive and Emotional Effects of Psilocybin

BACKGROUND

Serotonergic psychedelics, such as psilocybin, alter perceptual and cognitive systems that are functionally integrated with the amygdala. These changes can alter cognition and emotions that are hypothesized to contribute to their therapeutic utility. However, the neural mechanisms of cognitive and subcortical systems altered by psychedelics are not well understood.

METHODS

We used resting-state functional magnetic resonance images collected during a randomized, double-blind, placebo-controlled clinical trial of 24 healthy adults under 0.2 mg/kg psilocybin to estimate the directed (i.e., effective) changes between the amygdala and 3 large-scale resting-state networks involved in cognition. These networks are the default mode network, the salience network, and the central executive network.

RESULTS

We found a pattern of decreased top-down effective connectivity from these resting-state networks to the amygdala. Effective connectivity decreased within the default mode network and salience network but increased within the central executive network. These changes in effective connectivity were statistically associated with behavioral measures of altered cognition and emotion under the influence of psilocybin.

CONCLUSIONS

Our findings suggest that temporary amygdala signal attenuation is associated with mechanistic changes to resting-state network connectivity. These changes are significant for altered cognition and perception and suggest targets for research investigating the efficacy of psychedelic therapy for internalizing psychiatric disorders. More broadly, our study suggests the value of quantifying the brain's hierarchical organization using effective connectivity to identify important mechanisms for basic cognitive function and how they are integrated to give rise to subjective experiences.

Therapeutic potential of psychedelics: History, advancements, and unexplored frontiers

Psychedelics (serotonergic hallucinogens) are psychoactive substances that can alter perception and mood, and affect cognitive functions. These substances activate 5-HT2A receptors and may exert therapeutic effects. Some of the disorders for which psychedelic-assisted therapy have been studied include depression, addiction, anxiety and post-traumatic stress disorder. Despite the increasing number of studies reporting clinical effectiveness, with fewer negative symptoms and, additionally, minimal side effects, questions remain to be explored in the field of psychedelic medicine. Although progress has been achieved, there is still little understanding of the relationship among human brain and the modulation induced by these drugs. The present article aimed to describe, review and highlight the most promising findings in the literature regarding the (putative) therapeutic effects of psychedelics.

Reduction of alcohol use and increase in psychological flexibility after a naturalistic psychedelic experience: a retrospective survey

INTRODUCTION

Alcohol use can be significantly associated with negative social, professional, and health outcomes. Even more so, alcohol use disorder (AUD) is a critical public health issue and major avoidable risk factor. This study aimed to examine the effect of a naturalistic psychedelic experience on alcohol use and related measures.

METHODS

A retrospective online survey was conducted on 160 individuals who reported a psychedelic experience and a concomitant drinking habit but did not necessarily have an AUD. Demographic data, characteristics of the psychedelic experience, and changes in alcohol consumption and psychological flexibility were surveyed. Results: The mean number of drinking days per week and AUDIT scores significantly decreased after the psychedelic experience (P < .001). Subjects who quit or reduced drinking had a more severe AUD (P < .01) and lower psychological flexibility (P = .003) before the psychedelic session. Alcohol use reduction was significantly associated with the intensity of the mystical experience (P = .03). Psychological flexibility increased more in participants who reduced their alcohol use (P < .001), and the change in psychological flexibility was one of the predictors of alcohol use improvement (P = .003). Conclusion: Our findings suggest that a naturalistic psychedelic experience could be associated with a reduction in alcohol use and dependency. Such positive health outcomes can be associated with the intensity of the mystical experience as well as an increase in psychological flexibility.

Modelling phenomenological differences in aetiologically distinct visual hallucinations using deep neural networks

Visual hallucinations (VHs) are perceptions of objects or events in the absence of the sensory stimulation that would normally support such perceptions. Although all VHs share this core characteristic, there are substantial phenomenological differences between VHs that have different aetiologies, such as those arising from Neurodegenerative conditions, visual loss, or psychedelic compounds. Here, we examine the potential mechanistic basis of these differences by leveraging recent advances in visualising the learned representations of a coupled classifier and generative deep neural network-an approach we call 'computational (neuro)phenomenology'. Examining three aetiologically distinct populations in which VHs occur-Neurodegenerative conditions (Parkinson's Disease and Lewy Body Dementia), visual loss (Charles Bonnet Syndrome, CBS), and psychedelics-we identified three dimensions relevant to distinguishing these classes of VHs: realism (veridicality), dependence on sensory input (spontaneity), and complexity. By selectively tuning the parameters of the visualisation algorithm to reflect influence along each of these phenomenological dimensions we were able to generate 'synthetic VHs' that were characteristic of the VHs experienced by each aetiology. We verified the validity of this approach experimentally in two studies that examined the phenomenology of VHs in Neurodegenerative and CBS patients, and in people with recent psychedelic experience. These studies confirmed the existence of phenomenological differences across these three dimensions between groups, and crucially, found that the appropriate synthetic VHs were rated as being representative of each group's hallucinatory phenomenology. Together, our findings highlight the phenomenological diversity of VHs associated with distinct causal factors and demonstrate how a neural network model of visual phenomenology can successfully capture the distinctive visual characteristics of hallucinatory experience.

The Psychedelic Future of Post-Traumatic Stress Disorder Treatment

Post-traumatic stress disorder (PTSD) is a mental health condition that can occur following exposure to a traumatic experience. An estimated 12 million U.S. adults are presently affected by this disorder. Current treatments include psychological therapies (e.g., exposure-based interventions) and pharmacological treatments (e.g., selective serotonin reuptake inhibitors (SSRIs)). However, a significant proportion of patients receiving standard-of-care therapies for PTSD remain symptomatic, and new approaches for this and other trauma-related mental health conditions are greatly needed. Psychedelic compounds that alter cognition, perception, and mood are currently being examined for their efficacy in treating PTSD despite their current status as Drug Enforcement Administration (DEA)- scheduled substances. Initial clinical trials have demonstrated the potential value of psychedelicassisted therapy to treat PTSD and other psychiatric disorders. In this comprehensive review, we summarize the state of the science of PTSD clinical care, including current treatments and their shortcomings. We review clinical studies of psychedelic interventions to treat PTSD, trauma-related disorders, and common comorbidities. The classic psychedelics psilocybin, lysergic acid diethylamide (LSD), and N,N-dimethyltryptamine (DMT) and DMT-containing ayahuasca, as well as the entactogen 3,4-methylenedioxymethamphetamine (MDMA) and the dissociative anesthetic ketamine, are reviewed. For each drug, we present the history of use, psychological and somatic effects, pharmacology, and safety profile. The rationale and proposed mechanisms for use in treating PTSD and traumarelated disorders are discussed. This review concludes with an in-depth consideration of future directions for the psychiatric applications of psychedelics to maximize therapeutic benefit and minimize risk in individuals and communities impacted by trauma-related conditions.

Ayahuasca-induced personal death experiences: prevalence, characteristics, and impact on attitudes toward death, life, and the environment

Introduction

Despite an emerging understanding regarding the pivotal mechanistic role of subjective experiences that unfold during acute psychedelic states, very little has been done in the direction of better characterizing such experiences and determining their long-term impact. The present paper utilizes two cross-sectional studies for spotlighting - for the first time in the literature - the characteristics and outcomes of self-reported past experiences related to one's subjective sense of death during ayahuasca ceremonies, termed here Ayahuasca-induced Personal Death (APD) experiences.

Methods

Study 1 (n = 54) reports the prevalence, demographics, intensity, and impact of APDs on attitudes toward death, explores whether APDs are related with psychopathology, and reveals their impact on environmental concerns. Study 2 is a larger study (n = 306) aiming at generalizing the basic study 1 results regarding APD experience, and in addition, examining whether APDs is associated with self-reported coping strategies and values in life.

Results

Our results indicate that APDs occur to more than half of those participating in ayahuasca ceremonies, typically manifest as strong and transformative experiences, and are associated with an increased sense of transcending death (study 1), as well as the certainty in the continuation of consciousness after death (study 2). No associations were found between having undergone APD experiences and participants' demographics, personality type, and psychopathology. However, APDs were associated with increased self-reported environmental concern (study 1). These experiences also impact life in profound ways. APDs were found to be associated with increases in one's self-reported ability to cope with distress-causing life problems and the sense of fulfillment in life (study 2).

Discussion

The study's findings highlight the prevalence, safety and potency of death experiences that occur during ayahuasca ceremonies, marking them as possible mechanisms for psychedelics' long-term salutatory effects in non-clinical populations. Thus, the present results join other efforts of tracking and characterizing the profound subjective experiences that occur during acute psychedelic states.

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.

Gβγ subunit inhibitor decreases DOM-induced head twitch response via the PLCβ/IP3/Ca2+/ERK and cAMP signaling pathways

AIMS

(-)-2,5-dimethoxy-4-methylamphetamine (DOM) induces the head-twitch response (HTR) primarily by activating the serotonin 5-hydroxytryptamine 2A receptor (5-HT2A receptor) in mice. However, the mechanisms underlying 5-HT2A receptor activation and the HTR remain elusive. Gβγ subunits are a potential treatment target in numerous diseases. The present study investigated the mechanism whereby Gβγ subunits influence DOM-induced HTR.

MAIN METHODS

The effects of the Gβγ inhibitor 3',4',5',6'-tetrahydroxyspiro[2-benzofuran-3,9'-xanthene]-1-one (gallein) and antagonistic peptide βARKct (β-adrenergic receptor kinase C-terminal fragment) on DOM-induced HTR were studied via an HTR test. The activation of the phospholipase C β (PLCβ)/inositol triphosphate (IP3)/calcium (Ca2+) signaling pathway and extracellular signal-regulated kinase (ERK) following Gβγ subunit inhibition was detected by western blotting, Homogeneous Time-Resolved Fluorescence (HTRF) inositol phosphate (IP1) assay and Fluorometric Imaging Plate Reader (FLIPR) calcium 6 assay. The Gβγ subunit-mediated regulation of cyclic adenosine monophosphate (cAMP) was assessed via a GloSensor™ cAMP assay.

KEY FINDINGS

The Gβγ subunit inhibitors gallein and βARKct reduced DOM-induced HTR in C57BL/6J mice. Like the 5-HT2A receptor-selective antagonist (R)-[2,3-di(methoxy)phenyl]-[1-[2-(4-fluorophenyl)ethyl]piperidin-4-yl]methanol (M100907), gallein inhibited PLCβ phosphorylation (pPLCβ), IP1 production, Ca2+ transients, ERK1/2 phosphorylation (pERK1/2) and cAMP accumulation induced by DOM in human embryonic kidney (HEK) 293T cells stably or transiently transfected with the human 5-HT2A receptor. Moreover, PLCβ protein inhibitor 1-[6-[[(8R,9S,13S,14S,17S)-3-methoxy-13-methyl-6,7,8,9,11,12,14,15,16,17-decahydrocyclopenta[a]phenanthren-17-yl]amino]hexyl]pyrrole-2,5-dione (U73122) (10 nmol/mouse), intracellular Ca2+ blocker 6-[6-[6-[5-acetamido-4,6-dihydroxy-2-(sulfooxymethyl)oxan-3-yl]oxy-2-carboxy-4-hydroxy-5-sulfooxyoxan-3-yl]oxy-2-(hydroxymethyl)-5-(sulfoamino)-4-sulfooxyoxan-3-yl]oxy-3,4-dihydroxy-5-sulfooxyoxane-2-carboxylic acid (heparin) (5 nmol/mouse), L-type Ca2+ channel blocker 3-O-(2-methoxyethyl) 5-O-propan-2-yl 2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate (nimodipine) (4 mg/kg), mitogen extracellular regulating kinase 1/2 (MEK1/2) inhibitor (Z)-3-amino-3-(4-aminophenyl)sulfanyl-2-[2-(trifluoromethyl)phenyl]prop-2-enenitrile (SL327) (30 mg/kg), and Gαs protein selective antagonist 4,4',4″,4‴-(Carbonylbis-(imino-5,1,3-benzenetriylbis(carbonylimino)))tetrakisbenzene-1,3-disulfonic acid (NF449) (10 nmol/mouse) reduced DOM-induced HTR in C57BL/6J mice.

SIGNIFICANCE

The Gβγ subunits potentially mediate the HTR after 5-HT2A receptor activation via the PLCβ/IP3/Ca2+/ERK1/2 and cAMP signaling pathways. Inhibitors targeting the Gβγ subunits potentially inhibit the hallucinogenic effects of 5-HT2A receptor agonists.

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

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

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.

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.

Psilocybin history, action and reaction: A narrative clinical review

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

Psychedelic unselfing: self-transcendence and change of values in psychedelic experiences

Psychedelic experiences have been shown to both facilitate (re)connection to one's values and change values, including enhancing aesthetic appreciation, promoting pro-environmental attitudes, and encouraging prosocial behavior. This article presents an empirically informed framework of philosophical psychology to understand how self-transcendence relates to psychedelic value changes. Most of the observed psychedelic value changes are toward the self-transcendent values of Schwartz's value theory. As psychedelics also reliably cause various self-transcendent experiences (STEs), a parsimonious hypothesis is that STEs change values toward self-transcendent values. I argue that STEs indeed can lead to value changes, and discuss the morally relevant process of self-transcendence through Iris Murdoch's concept of "unselfing". I argue that overt egocentric concerns easily bias one's valuations. Unselfing reduces egocentric attributions of salience and enhances non-egocentric attention to the world, widening one's perspective and shifting evaluation toward self-transcendent modes. Values are inherently tied to various evaluative contexts, and unselfing can attune the individual to evaluative contexts and accompanying values beyond the self. Understood this way, psychedelics can provide temporarily enhanced access to self-transcendent values and function as sources of aspiration and value change. However, contextual factors can complicate whether STEs lead to long-term changes in values. The framework is supported by various research strands establishing empirical and conceptual connections between long-term differences in egocentricity, STEs, and self-transcendent values. Furthermore, the link between unselfing and value changes is supported by phenomenological and theoretical analysis of psychedelic experiences, as well as empirical findings on their long-term effects. This article furthers understanding of psychedelic value changes and contributes to discussions on whether value changes are justified, whether they result from cultural context, and whether psychedelics could function as tools of moral neuroenhancement.

A whole-brain model of the neural entropy increase elicited by psychedelic drugs

Psychedelic drugs, including lysergic acid diethylamide (LSD) and other agonists of the serotonin 2A receptor (5HT2A-R), induce drastic changes in subjective experience, and provide a unique opportunity to study the neurobiological basis of consciousness. One of the most notable neurophysiological signatures of psychedelics, increased entropy in spontaneous neural activity, is thought to be of relevance to the psychedelic experience, mediating both acute alterations in consciousness and long-term effects. However, no clear mechanistic explanation for this entropy increase has been put forward so far. We sought to do this here by building upon a recent whole-brain model of serotonergic neuromodulation, to study the entropic effects of 5HT2A-R activation. Our results reproduce the overall entropy increase observed in previous experiments in vivo, providing the first model-based explanation for this phenomenon. We also found that entropy changes were not uniform across the brain: entropy increased in all regions, but the larger effect were localised in visuo-occipital regions. Interestingly, at the whole-brain level, this reconfiguration was not well explained by 5HT2A-R density, but related closely to the topological properties of the brain's anatomical connectivity. These results help us understand the mechanisms underlying the psychedelic state and, more generally, the pharmacological modulation of whole-brain activity.

The prescription of psychedelic therapies in Australia and New Zealand: A brief survey of psychiatrists

OBJECTIVE

To explore the knowledge and attitudes of psychiatrists about psychedelics therapies.

METHOD

Access to a cross-sectional survey was distributed to psychiatrists through social media channels. Attitudes and knowledge about psychedelic therapies were recorded using Likert scales and ranking questions.

RESULTS

Fifty-eight complete responses were collected (44 fully trained +14 trainee RANZCP members). Greater than 85% of respondents agreed there is a shortfall in effective psychiatric treatments, and greater than 65% agreed that psychedelic therapies might address this shortfall. The psychiatrists did not consider themselves knowledgeable about psychedelic therapies, with 60% showing interest in further training on this topic. About 70% of the sample hold various concerns about psychedelic therapies, and more believe that the prescription of psychedelics should be limited to psychiatrists in the future.

CONCLUSION

Considering these results in the context of a rapidly changing landscape relating to psychedelic research and regulations, we suggest there is scope to develop up-to-date education about psychedelics for psychiatrists.

Can psychedelics enhance group psychotherapy? A discussion on the therapeutic factors

BACKGROUND

Despite the growth of psychedelic research, psychedelic-assisted group psychotherapy (PAGP) has received little attention in comparison to individual psychedelic-assisted psychotherapy models.

METHODS

In this article, we aim to discuss the therapeutic potential of PAGP, as well as outline existing models and the challenges of this approach. Using Irvin Yalom's 11 therapeutic factors of group therapy as a basic framework, we analyse current literature from clinical studies and neurobiological research relative to the topic of PAGP.

RESULTS

We argue that combining psychedelic substances and group psychotherapy may prove beneficial for increasing group connectedness and interpersonal learning, potentially enhancing prosocial behaviour with direct opportunities to practice newly acquired knowledge about previously maladaptive behavioural patterns. Challenges regarding this approach include a more rigid therapy structure and potential loss of openness from patients, which may be ameliorated by adequate therapeutic training.

CONCLUSION

We hope for this article to support clinical research on PAGP by presenting a therapeutic framework and outlining its mechanisms and challenges.

More than meets the eye: The role of sensory dimensions in psychedelic brain dynamics, experience, and therapeutics

Psychedelics are undergoing a major resurgence of scientific and clinical interest. While multiple theories and frameworks have been proposed, there is yet no universal agreement on the mechanisms underlying the complex effects of psychedelics on subjective experience and brain dynamics, nor their therapeutic benefits. Despite being prominent in psychedelic phenomenology and distinct from those elicited by other classes of hallucinogens, the effects of psychedelics on low-level sensory - particularly visual - dimensions of experience, and corresponding brain dynamics, have often been disregarded by contemporary research as 'epiphenomenal byproducts'. Here, we review available evidence from neuroimaging, pharmacology, questionnaires, and clinical studies; we propose extensions to existing models, provide testable hypotheses for the potential therapeutic roles of psychedelic-induced visual hallucinations, and simulations of visual phenomena relying on low-level cortical dynamics. In sum, we show that psychedelic-induced alterations in low-level sensory dimensions 1) are unlikely to be entirely causally reconducible to high-level alterations, but rather co-occur with them in a dialogical interplay, and 2) are likely to play a causally relevant role in determining high-level alterations and therapeutic outcomes. We conclude that reevaluating the currently underappreciated role of sensory dimensions in psychedelic states will be highly valuable for neuroscience and clinical practice, and that integrating low-level and domain-specific aspects of psychedelic effects into existing nonspecific models is a necessary step to further understand how these substances effect both acute and long-term change in the human brain.

Effective Connectivity of Functionally Anticorrelated Networks Under Lysergic Acid Diethylamide

BACKGROUND

Classic psychedelic-induced ego dissolution involves a shift in the sense of self and a blurring of the boundary between the self and the world. A similar phenomenon is identified in psychopathology and is associated with the balance of anticorrelated activity between the default mode network, which directs attention inward, and the salience network, which recruits the dorsal attention network to direct attention outward.

METHODS

To test whether changes in anticorrelated networks underlie the peak effects of lysergic acid diethylamide (LSD), we applied dynamic causal modeling to infer effective connectivity of resting-state functional magnetic resonance imaging scans from a study of 25 healthy adults who were administered 100 μg of LSD or placebo.

RESULTS

We found that inhibitory effective connectivity from the salience network to the default mode network became excitatory, and inhibitory effective connectivity from the default mode network to the dorsal attention network decreased under the peak effect of LSD.

CONCLUSIONS

The effective connectivity changes we identified may reflect diminution of the functional anticorrelation between resting-state networks that may be a key neural mechanism of LSD and underlie ego dissolution. Our findings suggest that changes to the sense of self and subject-object boundaries across different states of consciousness may depend upon the organized balance of effective connectivity of resting-state networks.

Psychedelics and Desistance From Crime: Lessons From the Concord Prison Experiment

Recent investigations of naturalistic psychedelic use purport that psychedelic therapies may be useful in criminal justice contexts for reducing recidivism. The present study applies interactionist theories of desistance to critically explore how psychedelic therapies could facilitate agentic self-transformation to support desistance from crime. Psychedelic experience reports written by inmates as part of the “Concord Prison Experiment” (CPE) were collected from the New York Public Library. Reports from 29 participants were then analyzed using a qualitative content analysis that employed both conventional and directed approaches. Participants frequently reported on changes in emotion and sense perception, interactions with other participants, and self-knowledge. Reports of self-knowledge often emerged from cognitive shifts that led to reflexive thought and novel insights regarding crime and criminality. These findings demonstrate how psychedelics can facilitate cognitive shifts in meaning conducive to inspiring desistance from crime. However, shortcomings of the CPE indicate that the social environment can hinder integration, by constraining the potential to enact changes in one’s life or realize meaningful insights through prosocial relationships. The combination of potentially harmful prison environments and the vulnerable states of consciousness generated by psychedelics should preclude investigations among actively incarcerated participants. Without addressing common social and structural barriers to successful reentry such as housing and employment, the efficacy of psychedelic-assisted therapy as a recidivism reducing intervention will be limited. Alternative approaches might explore how psychedelic therapy can address the psychological impacts of incarceration.

Neural Mechanisms and Psychology of Psychedelic Ego Dissolution

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

Psychosis and psychedelics: Historical entanglements and contemporary contrasts

Experiences of psychedelics and psychosis were deeply entangled in scientific practices in the mid-20th century, from uses of psychedelic drugs that could model psychosis, to detailed phenomenological comparisons of endogenous and drug-induced madness. After the moral panic of the 1960s shut down psychedelic research, however, these two phenomena became disentangled. In the decades following, the science of psychosis transformed, shedding the language of psychoanalysis, and adopting the new scientific veneer of psychiatry. Today, as psychedelic science re-emerges, the research programs surrounding psychosis and psychedelics now stand in stark contrast. Here, I look closely at how these research programs respond to questions related to what is worth measuring, what is worth investigating, and how we ought to respond to these experiences. This comparison reveals radically different assumptions and values that guide each research paradigm and shape clinical practice. While psychedelic research often includes scales that seek to capture experiences of mysticism, meaningfulness, and ego dissolution, research related to psychosis focuses on the measurement of pathological symptoms and functioning. Research into psychosis primarily seeks universal and reductionist causal explanations and interventions, while psychedelic research embraces the importance of set and setting in shaping unique experiences. Responses to psychedelic crisis involve warmth, compassion, and support, while responses to psychotic experiences often involve restraint, seclusion, and weapons. I argue that these differences contain important lessons for psychiatry. However, as psychedelic research struggles to meet regulatory requirements and fit within the paradigm of evidence-based medicine, these differences may quickly dissolve.

Psychological effects and subjective experiences of ayahuasca rituals in participants of two neoshamanic centers of Uruguay

Background

Ayahuasca's psychological and subjective effects were compared in rituals of two neoshamanic groups in Uruguay.

Aims

Compare, describe and analyze psychological effects and subjective experiences of ayahuasca ceremonies in two different groups: a psychospiritual holistic center, and a center specialized in substance use disorder's treatment.

Methods

A mixed qualitative-quantitative study was conducted, using the Hallucinogen Rating Scale for measuring psychological effects, and in-depth interviews for the description of ayahuasca subjective experiences. Data from both techniques were compared, analyzing convergences and differences.

Results

When comparing the two neoshamanic groups, significant differences with a medium-size effect were found in the psychological variables Affect (r = 0.47), Cognition (r = 0.36) and Perception (r = 0.36). The qualitative descriptions of ayahuasca experiences in the group with higher scores in those variables showed more frequent and complex experiences of emotional, cognitive, and perceptive content. Dissimilar results were found when comparing Intensity and Somaesthetic domains, with no significant results in the quantitative part, while in the qualitative part intensity was reported as “soft” in one group, and corporal experiences (e.g., purging effects) were especially manifested.

Conclusions

Stronger subjective experiences and higher psychological effects may be related to differences in the dosage and the setting of the centers. Emotional, cognitive, and perceptive psychological effects of ayahuasca rituals measured by the Hallucinogen Rating Scale, seem to be associated with more frequent and complex subjective experiences in the mentioned domains. Qualitative group differences in corporal alterations and the overall intensity of the experience differed from non-significant results of the quantitative part of the study.

Do psychedelics change beliefs?

Renewed interest in psychedelics has reignited the debate about whether and how they change human beliefs. In both the clinical and social-cognitive domains, psychedelic consumption may be accompanied by profound, and sometimes lasting, belief changes. We review these changes and their possible underlying mechanisms. Rather than inducing de novo beliefs, we argue psychedelics may instead change the impact of affect and of others' suggestions on how beliefs are imputed. Critically, we find that baseline beliefs (in the possible effects of psychedelics, for example) might color the acute effects of psychedelics as well as longer-term changes. If we are to harness the apparent potential of psychedelics in the clinic and for human flourishing more generally, these possibilities must be addressed empirically.

Validation of a French Version of the Mystical Experience Questionnaire with Retrospective Reports of the Most Significant Psychedelic Experience among French Users

Mystical experiences triggered by psychedelic drugs predict symptom reduction in various psychiatric disorders, and increased well-being in healthy individuals. This work aimed at validating a French version of a tool used to measure mystical experiences: the Revised Mystical Experience Questionnaire-30 items (MEQ30). Construct validity, internal consistencies, concurrent, discriminant, and predictive validities of the French MEQ30 were examined using data about the most significant psychedelic experience of 320 French individuals. Results showed that the original four-factor (i.e., mystical, positive mood, transcendence, and ineffability) structure fit the data best, with good to excellent statistical indices. Total French MEQ30 score was strongly associated with subjective ratings of the mystical (i.e., mystical, spiritual, or religious, and personally significant) and drug intensity-related qualities of the experience, but not with non-mystical (i.e., fun, inebriating, and easy) qualities. Moreover, French MEQ30 score was a significant predictor of subjective positive changes in psychological well-being, relations with self and others, feeling of proximity or connection with nature, and creativity, whereas drug intensity-related and non-mystical qualities of the experience were not, or were only weakly associated with such changes. This French version of the MEQ30 seems to be an appropriate tool for measuring mystical experiences among French speaking individuals.

Reduced Precision Underwrites Ego Dissolution and Therapeutic Outcomes Under Psychedelics

Evidence suggests classic psychedelics reduce the precision of belief updating and enable access to a range of alternate hypotheses that underwrite how we make sense of the world. This process, in the higher cortices, has been postulated to explain the therapeutic efficacy of psychedelics for the treatment of internalizing disorders. We argue reduced precision also underpins change to consciousness, known as “ego dissolution,” and that alterations to consciousness and attention under psychedelics have a common mechanism of reduced precision of Bayesian belief updating. Evidence, connecting the role of serotonergic receptors to large-scale connectivity changes in the cortex, suggests the precision of Bayesian belief updating may be a mechanism to modify and investigate consciousness and attention.

The Acceptance/Avoidance-Promoting Experiences Questionnaire (APEQ): A theory-based approach to psychedelic drugs' effects on psychological flexibility

BACKGROUND

Many benefits and some harms associated with psychedelic use could be attributable to these drugs' acceptance/avoidance-promoting effects and corresponding changes in psychological flexibility. Underlying psychological mechanisms are insufficiently understood.

AIM

The purpose of this study was the validation of a psychological model of acceptance/avoidance-promoting psychedelic experiences, which included the development of a theory-based self-report instrument: the Acceptance/Avoidance-Promoting Experiences Questionnaire (APEQ). Its two main scales, acceptance-related experience (ACE) and avoidance-related experience (AVE), represent the theorized model's core constructs. We aimed to test the model's central assumptions of complementarity (ACE and AVE may occur alternatingly but not simultaneously, and are therefore empirically independent), intertwinedness (subaspects within ACE and AVE are mutually contingent and therefore highly inter-correlated), context-dependence (ACE and AVE depend on context factors) and interaction (longer-term outcomes depend on the interplay between ACE and AVE).

METHOD

A bilingual retrospective online survey including 997 English- and 836 German-speaking participants. Each participant reported on one psychedelic experience occasioned by lysergic acid diethylamide (LSD), psilocybin, mescaline, or ayahuasca.

RESULTS

Whereas ACE and AVE were found to be relatively independent aspects of participants' reported psychedelic experiences (complementarity), their subaspects were mostly distinguishable but strongly correlated among each other (intertwinedness). Therapeutic, escapist, and hedonic use motives were differentially associated with ACE and AVE (context-dependence), which were in turn associated with retrospective changes in psychological flexibility following participants' reported experiences. The positive association between ACE and increased psychological flexibility was significantly moderated by AVE (interaction).

CONCLUSION

These results provide an initial validation of the APEQ and its underlying theoretical model, suggesting the two can help clarify the psychological mechanisms of psychedelic-induced benefits and harms. Both should be further investigated in prospective-longitudinal and clinical studies.

The promise of psychedelic research

The use of psychedelics as medicines and for overall better brain health is potentially one of the most transformative developments given their immediate and long-lasting therapeutic effects across a plethora of neuropsychiatric disorders and, more recently, some neurodegenerative diseases. The US psychedelic drugs market is forecasted to grow by 16.3% by 2027 due to the increasing prevalence of treatment-resistant depression and mental health disorders. Decades-long restrictions, which date back to when psychedelics were declared controlled substances in 1970, have been lifted to allow researchers to publish on the therapeutic benefits of psychedelics. This review will feature the incredible depth of research underway revealing how psychedelics impact brain structure and function to treat mental health and other neurological disorders.

Serotonergic psychedelics for depression: What do we know about neurobiological mechanisms of action?

INTRODUCTION

Current treatment options for major depressive disorder (MDD) have limited efficacy and are associated with adverse effects. Recent studies investigating the antidepressant effect of serotonergic psychedelics-also known as classic psychedelics-have promising preliminary results with large effect sizes. In this context, we conducted a review of the putative neurobiological underpinnings of the mechanism of antidepressant action of these drugs.

METHODS

A narrative review was conducted using PubMed to identify published articles evaluating the antidepressant mechanism of action of serotonergic psychedelics.

RESULTS

Serotonergic psychedelics have serotonin (5HT)2A agonist or partial agonist effects. Their rapid antidepressant effects may be mediated-in part-by their potent 5HT2A agonism, leading to rapid receptor downregulation. In addition, these psychedelics impact brain derived neurotrophic factor and immunomodulatory responses, both of which may play a role in their antidepressant effect. Several neuroimaging and neurophysiology studies evaluating mechanistic change from a network perspective can help us to further understand their mechanism of action. Some, but not all, data suggest that psychedelics may exert their effects, in part, by disrupting the activity of the default mode network, which is involved in both introspection and self-referential thinking and is over-active in MDD.

CONCLUSION

The mechanisms of action underlying the antidepressant effect of serotonergic psychedelics remains an active area of research. Several competing theories are being evaluated and more research is needed to determine which ones are supported by the most robust evidence.

Psychedelic experience dose-dependently modulated by cannabis: results of a prospective online survey

RATIONALE

Classic psychedelics are currently being studied as novel treatments for a range of psychiatric disorders. However, research on how psychedelics interact with other psychoactive substances remains scarce.

OBJECTIVES

The current study aimed to explore the subjective effects of psychedelics when used alongside cannabis.

METHODS

Participants (n = 321) completed a set of online surveys at 2 time points: 7 days before, and 1 day after a planned experience with a serotonergic psychedelic. The collected data included demographics, environmental factors (so-called setting) and five validated questionnaires: Mystical Experience Questionnaire (MEQ), visual subscales of Altered States of Consciousness Questionnaire (ASC-Vis), Challenging Experience Questionnaire (CEQ), Ego Dissolution Inventory (EDI) and Emotional Breakthrough Inventory (EBI). Participants were grouped according to whether they had reported using no cannabis (n = 195) or low (n = 53), medium (n = 45) or high (n = 28) dose, directly concomitant with the psychedelic. Multivariate analysis of covariance (MANCOVA) and contrasts was used to analyse differences in subjective effects between groups while controlling for potential confounding contextual 'setting' variables.

RESULTS

The simultaneous use of cannabis together with classic serotonergic psychedelics was associated with more intense psychedelic experience across a range of measures: a linear relationship was found between dose and MEQ, ASC-Vis and EDI scores, while a quadratic relationship was found for CEQ scores. No relationship was found between the dose of cannabis and the EBI.

CONCLUSIONS

Results imply a possible interaction between the cannabis and psychedelic on acute subjective experiences; however, design limitations hamper our ability to draw firm inferences on directions of causality and the clinical implications of any such interactions.

Administration of N,N-dimethyltryptamine (DMT) in psychedelic therapeutics and research and the study of endogenous DMT

As with all drugs, the route, form, and/or dose of a substance administered or applied can play a defining role in its overall pharmacology and use as a therapeutic. This review will focus on these factors as they relate to the psychedelic N,N-dimethyltryptamine (DMT). It will examine the positive and negative aspects of different formulations and routes of administration of DMT and the observed effects from such administrations in the form of ayahuasca teas; oral "pharmahuasca"; injections by intravenous (IV) and intramuscular (IM) routes; inhalation, insufflation; and other routes; and high-dose, low-dose, and "micro-dose" effects. The review will consider possible oral route of administration alternatives that would not require concomitant use of a monoamine oxidase inhibitor. The review will then address the current research findings for DMT from in vivo and in vitro studies as well as the possibility that these findings may be revealing the role of endogenous DMT in normal brain function.

Analysis of recreational psychedelic substance use experiences classified by substance

RATIONALE AND OBJECTIVES

Differences among psychedelic substances regarding their subjective experiences are clinically and scientifically interesting. Quantitative linguistic analysis is a powerful tool to examine such differences. This study compared five psychedelic substance report groups and a non-psychedelic report group on quantitative linguistic markers of psychological states and processes derived from recreational use-based online experience reports.

METHODS

Using 2947 publicly available online reports, we compared Ayahuasca and N,N-dimethyltryptamine (DMT, analyzed together), ketamine, lysergic acid diethylamide (LSD), 3,4-methylenedioxymethamphetamine (MDMA), psilocybin (mushroom), and antidepressant drug use experiences. We examined word frequencies related to various psychological states and processes and semantic proximity to psychedelic and mystical experience scales.

RESULTS

Linguistic markers of psychological function indicated distinct effect profiles. For example, MDMA experience reports featured an emotionally intensifying profile accompanied by many cognitive process words and dynamic-personal language. In contrast, Ayahuasca and DMT experience reports involved relatively little emotional language, few cognitive process words, increased analytical thinking-associated language, and the most semantic similarity with psychedelic and mystical experience descriptions. LSD, psilocybin mushroom, and ketamine reports showed only small differences on the emotion-, analytical thinking-, psychedelic, and mystical experience-related language outcomes. Antidepressant reports featured more negative emotional and cognitive process-related words, fewer positive emotional and analytical thinking-related words, and were generally not similar to mystical and psychedelic language.

CONCLUSION

This article addresses an existing research gap regarding the comparison of different psychedelic drugs on linguistic profiles of psychological states, processes, and experiences. The large sample of experience reports involving multiple psychedelic drugs provides valuable information that would otherwise be difficult to obtain. The results could inform experimental research into psychedelic drug effects in healthy populations and clinical trials for psychedelic treatments of psychiatric problems.

Psychedelic Therapy's Transdiagnostic Effects: A Research Domain Criteria (RDoC) Perspective

Accumulating clinical evidence shows that psychedelic therapy, by synergistically combining psychopharmacology and psychological support, offers a promising transdiagnostic treatment strategy for a range of disorders with restricted and/or maladaptive habitual patterns of emotion, cognition and behavior, notably, depression (MDD), treatment resistant depression (TRD) and addiction disorders, but perhaps also anxiety disorders, obsessive-compulsive disorder (OCD), Post-Traumatic Stress Disorder (PTSD) and eating disorders. Despite the emergent transdiagnostic evidence, the specific clinical dimensions that psychedelics are efficacious for, and associated underlying neurobiological pathways, remain to be well-characterized. To this end, this review focuses on pre-clinical and clinical evidence of the acute and sustained therapeutic potential of psychedelic therapy in the context of a transdiagnostic dimensional systems framework. Focusing on the Research Domain Criteria (RDoC) as a template, we will describe the multimodal mechanisms underlying the transdiagnostic therapeutic effects of psychedelic therapy, traversing molecular, cellular and network levels. These levels will be mapped to the RDoC constructs of negative and positive valence systems, arousal regulation, social processing, cognitive and sensorimotor systems. In summarizing this literature and framing it transdiagnostically, we hope we can assist the field in moving toward a mechanistic understanding of how psychedelics work for patients and eventually toward a precise-personalized psychedelic therapy paradigm.

Beating Pain with Psychedelics: Matter over Mind?

Basic pain research has shed light on key cellular and molecular mechanisms underlying nociceptive and phenomenological aspects of pain. Despite these advances, [[we still yearn for] the discovery of novel therapeutic strategies to address the unmet needs of about 70% of chronic neuropathic pain patients whose pain fails to respond to opioids as well as to other conventional analgesic agents. Importantly, a substantial body of clinical observations over the past decade cumulatively suggests that the psychedelic class of drugs may possess heuristic value for understanding and treating chronic pain conditions. The present review presents a theoretical framework for hitherto insufficiently understood neuroscience-based mechanisms of psychedelics' potential analgesic effects. To that end, searches of PubMed-indexed journals were performed using the following Medical Subject Headings' terms: pain, analgesia, inflammatory, brain connectivity, ketamine, psilocybin, functional imaging, and dendrites. Recursive sets of scientific and clinical evidence extracted from this literature review were summarized within the following key areas: (1) studies employing psychedelics for alleviation of physical and emotional pain; (2) potential neuro-restorative effects of psychedelics to remediate the impaired connectivity underlying the dissociation between pain-related conscious states/cognitions and the subcortical activity/function leading to the eventual chronicity through immediate and long-term effects on dentritic plasticity; (3) anti-neuroinflammatory and pro-immunomodulatory actions of psychedelics as the may pertain to the role of these factors in the pathogenesis of neuropathic pain; (4) safety, legal, and ethical consideration inherent in psychedelics' pharmacotherapy. In addition to direct beneficial effects in terms of reduction of pain and suffering, psychedelics' inclusion in the analgesic armamentarium will contribute to deeper and more sophisticated insights not only into pain syndromes but also into frequently comorbid psychiatric condition associated with emotional pain, e.g., depressive and anxiety disorders. Further inquiry is clearly warranted into the above areas that have potential to evolve into further elucidate the mechanisms of chronic pain and affective disorders, and lead to the development of innovative, safe, and more efficacious neurobiologically-based therapeutic approaches.

Psychedelics, Sociality, and Human Evolution

Our hominin ancestors inevitably encountered and likely ingested psychedelic mushrooms throughout their evolutionary history. This assertion is supported by current understanding of: early hominins' paleodiet and paleoecology; primate phylogeny of mycophagical and self-medicative behaviors; and the biogeography of psilocybin-containing fungi. These lines of evidence indicate mushrooms (including bioactive species) have been a relevant resource since the Pliocene, when hominins intensified exploitation of forest floor foods. Psilocybin and similar psychedelics that primarily target the serotonin 2A receptor subtype stimulate an active coping strategy response that may provide an enhanced capacity for adaptive changes through a flexible and associative mode of cognition. Such psychedelics also alter emotional processing, self-regulation, and social behavior, often having enduring effects on individual and group well-being and sociality. A homeostatic and drug instrumentalization perspective suggests that incidental inclusion of psychedelics in the diet of hominins, and their eventual addition to rituals and institutions of early humans could have conferred selective advantages. Hominin evolution occurred in an ever-changing, and at times quickly changing, environmental landscape and entailed advancement into a socio-cognitive niche, i.e., the development of a socially interdependent lifeway based on reasoning, cooperative communication, and social learning. In this context, psychedelics' effects in enhancing sociality, imagination, eloquence, and suggestibility may have increased adaptability and fitness. We present interdisciplinary evidence for a model of psychedelic instrumentalization focused on four interrelated instrumentalization goals: management of psychological distress and treatment of health problems; enhanced social interaction and interpersonal relations; facilitation of collective ritual and religious activities; and enhanced group decision-making. The socio-cognitive niche was simultaneously a selection pressure and an adaptive response, and was partially constructed by hominins through their activities and their choices. Therefore, the evolutionary scenario put forward suggests that integration of psilocybin into ancient diet, communal practice, and proto-religious activity may have enhanced hominin response to the socio-cognitive niche, while also aiding in its creation. In particular, the interpersonal and prosocial effects of psilocybin may have mediated the expansion of social bonding mechanisms such as laughter, music, storytelling, and religion, imposing a systematic bias on the selective environment that favored selection for prosociality in our lineage.

The Effects of Tryptamine Psychedelics in the Brain: A meta-Analysis of Functional and Review of Molecular Imaging Studies

There is an increasing interest in the neural effects of psychoactive drugs, in particular tryptamine psychedelics, which has been incremented by the proposal that they have potential therapeutic benefits, based on their molecular mimicry of serotonin. It is widely believed that they act mainly through 5HT2A receptors but their effects on neural activation of distinct brain systems are not fully understood. We performed a quantitative meta-analysis of brain imaging studies to investigate the effects of substances within this class (e.g., LSD, Psilocybin, DMT, Ayahuasca) in the brain from a molecular and functional point of view. We investigated the question whether the changes in activation patterns and connectivity map into regions with larger 5HT1A/5HT2A receptor binding, as expected from indolaemine hallucinogens (in spite of the often reported emphasis only on 5HT2AR). We did indeed find that regions with changed connectivity and/or activation patterns match regions with high density of 5HT2A receptors, namely visual BA19, visual fusiform regions in BA37, dorsal anterior and posterior cingulate cortex, medial prefrontal cortex, and regions involved in theory of mind such as the surpramarginal gyrus, and temporal cortex (rich in 5HT1A receptors). However, we also found relevant patterns in other brain regions such as dorsolateral prefrontal cortex. Moreover, many of the above-mentioned regions also have a significant density of both 5HT1A/5HT2A receptors, and available PET studies on the effects of psychedelics on receptor occupancy are still quite scarce, precluding a metanalytic approach. Finally, we found a robust neuromodulatory effect in the right amygdala. In sum, the available evidence points towards strong neuromodulatory effects of tryptamine psychedelics in key brain regions involved in mental imagery, theory of mind and affective regulation, pointing to potential therapeutic applications of this class of substances.

Neuropsychological Functioning in Users of Serotonergic Psychedelics - A Systematic Review and Meta-Analysis

Background: Serotonergic psychedelics (SPs) like LSD, psilocybin, DMT, and mescaline are a heterogeneous group of substances that share agonism at 5-HT2a receptors. Besides the ability of these substances to facilitate profoundly altered states of consciousness, persisting psychological effects have been reported after single administrations, which outlast the acute psychedelic effects. In this review and meta-analysis, we investigated if repeated SP use associates with a characteristic neuropsychological profile indicating persisting effects on neuropsychological function. Methods: We conducted a systematic review of studies investigating the neuropsychological performance in SP users, searching studies in Medline, Web of Science, embase, ClinicalTrials.gov, and EudraCT. Studies were included if they reported at least one neuropsychological measurement in users of SPs. Studies comparing SP users and non-users that reported mean scores and standard deviations were included in an exploratory meta-analysis. Results: 13 studies (N = 539) published between 1969 and 2020 were included in this systematic review. Overall, we found that only three SPs were specifically investigated: ayahuasca (6 studies, n = 343), LSD (5 studies, n = 135), and peyote (1 study, n = 61). However, heterogeneity of the methodological quality was high across studies, with matching problems representing the most important limitation. Across all SPs, no uniform pattern of neuropsychological impairment was identified. Rather, the individual SPs seemed to be associated with distinct neuropsychological profiles. For instance, one study (n = 42) found LSD users to perform worse in trials A and B of the Trail-Making task, whereas meta-analytic assessment (5 studies, n = 352) of eleven individual neuropsychological measures indicated a better performance of ayahuasca users in the Stroop incongruent task (p = 0.03) and no differences in the others (all p > 0.05). Conclusion: The majority of the included studies were not completely successful in controlling for confounders such as differences in non-psychedelic substance use between SP-users and non-users. Our analysis suggests that LSD, ayahuasca and peyote may have different neuropsychological consequences associated with their use. While LSD users showed reduced executive functioning and peyote users showed no differences across domains, there is some evidence that ayahuasca use is associated with increased executive functioning.

Pharmacologic Similarities and Differences Among Hallucinogens

Hallucinogens constitute a unique class of substances that cause changes in the user's thoughts, perceptions, and mood through various mechanisms of action. Although the serotonergic hallucinogens such as lysergic acid diethylamide, psilocybin, and N,N-dimethyltryptamine have been termed the classical hallucinogens, many hallucinogens elicit their actions through other mechanisms such as N-methyl-D-aspartate receptor antagonism, opioid receptor agonism, or inhibition of the reuptake of monoamines including serotonin, norepinephrine, and dopamine. The aim of this article is to compare the pharmacologic similarities and differences among substances within the hallucinogen class and their impact on physical and psychiatric effects. Potential toxicities, including life-threatening and long-term effects, will be reviewed.

Sociodemographic, Circumstantial, and Psychopathological Predictors of Involuntary Admission of Patients with Acute Psychosis

Studies have consistently determined that patients with acute psychosis are more likely to be involuntarily admitted, although few studies examine specific risk factors of involuntary admission (IA) among this patient group. Data from all patients presenting in the psychiatric emergency department (PED) over a period of one year were extracted. Acute psychosis was identified using specific diagnostic criteria. Predictors of IA were determined using logistic regression analysis. Out of 2533 emergency consultations, 597 patients presented with symptoms of acute psychosis, of whom 118 were involuntarily admitted (19.8%). Involuntarily admitted patients were more likely to arrive via police escort (odds ratio (OR) 10.94) or ambulance (OR 2.95), live in a psychiatric residency/nursing home (OR 2.76), report non-adherence to medication (OR 2.39), and were less likely to suffer from (comorbid) substance abuse (OR 0.53). Use of mechanical restraint was significantly associated with IA (OR 13.31). Among psychopathological aspects, aggressiveness was related to the highest risk of IA (OR 6.18), followed by suicidal intent (OR 5.54), disorientation (OR 4.66), tangential thinking (OR 3.95), and suspiciousness (OR 2.80). Patients stating fears were less likely to be involuntarily admitted (OR 0.25). By understanding the surrounding influencing factors, patient care can be improved with the aim of reducing the use of coercion.

Current Perspective on the Therapeutic Preset for Substance-Assisted Psychotherapy

The present narrative review is the first in a series of reviews about the appropriate conduct in substance-assisted psychotherapy (SAPT). It outlines a current perspective onpreconditions and theoretical knowledge that have been identified as valuable in the literaturefor appropriate therapeutic conduct in SAPT. In this context, considerations regarding ethics and the spiritual emphasis of the therapeutic approaches are discussed. Further, current methods, models, and concepts of psychological mechanism of action and therapeutic effects of SAPT are summarized, and similarities between models, approaches, and potential mediators for therapeutic effects are outlined. It is argued that a critical assessment of the literature might indicate that the therapeutic effect of SAPT may be mediated by intra- and interpersonal variables within the therapeutic context rather than specific therapeutic models per se. The review provides a basis for the development and adaptation of future investigations, therapeutic models, training programs for therapists, and those interested in the therapeutic potential of SAPT. Limitations and future directions for research are discussed.

Research abuses against people of colour and other vulnerable groups in early psychedelic research

There is a growing resurgence in the study of psychedelic medicines for the treatment of mental health and substance use disorders. However, certain early investigations are marred by questionable research methods, abuses against research participants, and covert Central Intelligence Agency financial involvement. The purpose of this study was to understand how and to what extent people of colour and other vulnerable populations, specifically, individuals who were incarcerated or incapacitated due to mental health issues (inpatients with psychotic disorders), were exploited during the first wave of psychedelic research in the USA (1950-1980). To do so, we reviewed available empirical publications according to current ethical standards. Variables of interest included race and ethnicity of participants, population vulnerability, drug administration conditions, informed consent and undue influence. Our findings draw attention to the history of research abuses against people of colour in Western psychedelic research. In light of these findings, we urge a call-to-action to current psychedelic researchers to prioritise culturally inclusive and socially responsible research methods in current and future studies.

The Potential Role of Psychedelic Drugs in Mental Health Care of the Future

Serotonergic psychedelics such as psilocybin, lysergic acid diethylamide (LSD), or dimethyltryptamine (DMT), as well as psychoactive drugs that trigger phenomenologically- related experiences like 3,4-methylenedioxymethamphetamine (MDMA) and ketamine, belong to the most promising treatment approaches in contemporary psychiatry. Psychedelic-assisted psychotherapy is not only a new treatment paradigm in psychopharmacology, but it also requires a redefinition of psychotherapeutic processes and the contextualization of psychopharmacological interventions within a new treatment infrastructure. Crucial for future practice and research in the field are (1) informed patient referral and co-treatment practices, (2) screening (e. g., choosing the right patients for these therapies), (3) the dosing preparation sessions, (4) the assisted dosing sessions as well as after-care procedures such as (5) psychological integration and (6) supporting the development of structured patient communities. Definition of future treatment delivery infrastructures and requirements for therapist training are further challenges for research and practice. Finally, the implementation of psychedelic-assisted psychotherapy in routine mental health care must be embedded into public communication about the potential and risks of these innovative therapeutic approaches. This paper provides a synopsis of challenges for practitioners, researchers, and regulators to be addressed in the approval processes of psychedelics.

Using computable knowledge mined from the literature to elucidate confounders for EHR-based pharmacovigilance

INTRODUCTION

Drug safety research asks causal questions but relies on observational data. Confounding bias threatens the reliability of studies using such data. The successful control of confounding requires knowledge of variables called confounders affecting both the exposure and outcome of interest. However, causal knowledge of dynamic biological systems is complex and challenging. Fortunately, computable knowledge mined from the literature may hold clues about confounders. In this paper, we tested the hypothesis that incorporating literature-derived confounders can improve causal inference from observational data.

METHODS

We introduce two methods (semantic vector-based and string-based confounder search) that query literature-derived information for confounder candidates to control, using SemMedDB, a database of computable knowledge mined from the biomedical literature. These methods search SemMedDB for confounders by applying semantic constraint search for indications treated by the drug (exposure) and that are also known to cause the adverse event (outcome). We then include the literature-derived confounder candidates in statistical and causal models derived from free-text clinical notes. For evaluation, we use a reference dataset widely used in drug safety containing labeled pairwise relationships between drugs and adverse events and attempt to rediscover these relationships from a corpus of 2.2 M NLP-processed free-text clinical notes. We employ standard adjustment and causal inference procedures to predict and estimate causal effects by informing the models with varying numbers of literature-derived confounders and instantiating the exposure, outcome, and confounder variables in the models with dichotomous EHR-derived data. Finally, we compare the results from applying these procedures with naive measures of association (χ2 and reporting odds ratio) and with each other.

RESULTS AND CONCLUSIONS

We found semantic vector-based search to be superior to string-based search at reducing confounding bias. However, the effect of including more rather than fewer literature-derived confounders was inconclusive. We recommend using targeted learning estimation methods that can address treatment-confounder feedback, where confounders also behave as intermediate variables, and engaging subject-matter experts to adjudicate the handling of problematic covariates.

LSD alters dynamic integration and segregation in the human brain

Investigating changes in brain function induced by mind-altering substances such as LSD is a powerful method for interrogating and understanding how mind interfaces with brain, by connecting novel psychological phenomena with their neurobiological correlates. LSD is known to increase measures of brain complexity, potentially reflecting a neurobiological correlate of the especially rich phenomenological content of psychedelic-induced experiences. Yet although the subjective stream of consciousness is a constant ebb and flow, no studies to date have investigated how LSD influences the dynamics of functional connectivity in the human brain. Focusing on the two fundamental network properties of integration and segregation, here we combined graph theory and dynamic functional connectivity from resting-state functional MRI to examine time-resolved effects of LSD on brain networks properties and subjective experiences. Our main finding is that the effects of LSD on brain function and subjective experience are non-uniform in time: LSD makes globally segregated sub-states of dynamic functional connectivity more complex, and weakens the relationship between functional and anatomical connectivity. On a regional level, LSD reduces functional connectivity of the anterior medial prefrontal cortex, specifically during states of high segregation. Time-specific effects were correlated with different aspects of subjective experiences; in particular, ego dissolution was predicted by increased small-world organisation during a state of high global integration. These results reveal a more nuanced, temporally-specific picture of altered brain connectivity and complexity under psychedelics than has previously been reported.

Psychedelics and Neuroplasticity: A Systematic Review Unraveling the Biological Underpinnings of Psychedelics

Clinical studies suggest the therapeutic potential of psychedelics, including ayahuasca, DMT, psilocybin, and LSD, in stress-related disorders. These substances induce cognitive, antidepressant, anxiolytic, and antiaddictive effects suggested to arise from biological changes similar to conventional antidepressants or the rapid-acting substance ketamine. The proposed route is by inducing brain neuroplasticity. This review attempts to summarize the evidence that psychedelics induce neuroplasticity by focusing on psychedelics' cellular and molecular neuroplasticity effects after single and repeated administration. When behavioral parameters are encountered in the selected studies, the biological pathways will be linked to the behavioral effects. Additionally, knowledge gaps in the underlying biology of clinical outcomes of psychedelics are highlighted. The literature searched yielded 344 results. Title and abstract screening reduced the sample to 35; eight were included from other sources, and full-text screening resulted in the final selection of 16 preclinical and four clinical studies. Studies (n = 20) show that a single administration of a psychedelic produces rapid changes in plasticity mechanisms on a molecular, neuronal, synaptic, and dendritic level. The expression of plasticity-related genes and proteins, including Brain-Derived Neurotrophic Factor (BDNF), is changed after a single administration of psychedelics, resulting in changed neuroplasticity. The latter included more dendritic complexity, which outlasted the acute effects of the psychedelic. Repeated administration of a psychedelic directly stimulated neurogenesis and increased BDNF mRNA levels up to a month after treatment. Findings from the current review demonstrate that psychedelics induce molecular and cellular adaptations related to neuroplasticity and suggest those run parallel to the clinical effects of psychedelics, potentially underlying them. Future (pre)clinical research might focus on deciphering the specific cellular mechanism activated by different psychedelics and related to long-term clinical and biological effects to increase our understanding of the therapeutic potential of these compounds.

The entropic tongue: Disorganization of natural language under LSD

Serotonergic psychedelics have been suggested to mirror certain aspects of psychosis, and, more generally, elicit a state of consciousness underpinned by increased entropy of on-going neural activity. We investigated the hypothesis that language produced under the effects of lysergic acid diethylamide (LSD) should exhibit increased entropy and reduced semantic coherence. Computational analysis of interviews conducted at two different time points after 75 μg of intravenous LSD verified this prediction. Non-semantic analysis of speech organization revealed increased verbosity and a reduced lexicon, changes that are more similar to those observed during manic psychoses than in schizophrenia, which was confirmed by direct comparison with reference samples. Importantly, features related to language organization allowed machine learning classifiers to identify speech under LSD with accuracy comparable to that obtained by examining semantic content. These results constitute a quantitative and objective characterization of disorganized natural speech as a landmark feature of the psychedelic state.