Replication and extension of a model predicting response to psilocybin

Psychiatric risks for worsened mental health after psychedelic use

BACKGROUND

Resurgent psychedelic research has largely supported the safety and efficacy of psychedelic therapy for the treatment of various psychiatric disorders. As psychedelic use and therapy increase in prevalence, so does the importance of understanding associated risks. Cases of prolonged negative psychological responses to psychedelic therapy seem to be rare; however, studies are limited by biases and small sample sizes. The current analytical approach was motivated by the question of whether rare but significant adverse effects have been under-sampled in psychedelic research studies.

METHODS

A "bottom margin analysis" approach was taken to focus on negative responders to psychedelic use in a pool of naturalistic, observational prospective studies (N = 807). We define "negative response" by a clinically meaningful decline in a generic index of mental health, that is, one standard error from the mean decrease in psychological well-being 4 weeks post-psychedelic use (vs pre-use baseline). We then assessed whether a history of diagnosed mental illness can predict negative responses.

RESULTS

We find that 16% of the cohort falls into the "negative responder" subset. Parsing the sample by self-reported history of psychiatric diagnoses, results revealed a disproportionate prevalence of negative responses among those reporting a prior personality disorder diagnosis (31%). One multivariate regression model indicated a greater than four-fold elevated risk of adverse psychological responses to psychedelics in the personality disorder subsample (b = 1.425, p < 0.05).

CONCLUSION

We infer that the presence of a personality disorder may represent an elevated risk for psychedelic use and hypothesize that the importance of psychological support and good therapeutic alliance may be increased in this population.

What Predicts Beneficial Outcomes in Psychedelic Use? A Quantitative Content Analysis of Psychedelic Health Outcomes

Interest in psychedelics and their possible therapeutic potential has been growing. Metaphysical belief theory asserts that these benefits stem from the adoption of comforting supernatural beliefs following a mystical experience. By contrast, predictive self-binding theory suggests that the beneficial outcomes of psychedelics are primarily driven by psychological insights. The present study tests these competing models of psychedelic benefits. We conducted a quantitative content analysis on unsolicited self-reports of psychedelic users available on Erowid.org, to examine the potential relations between psychological insight, ego dissolution, therapeutic intent, altered metaphysical belief, and enduring health outcomes. We randomly selected, coded, and analyzed two hundred forty psychedelic experience reports from the website. Path analysis using structural equation modeling showed that psychological insight, not metaphysical beliefs, uniquely predicted beneficial outcomes. Moreover, beneficial outcomes' positive relation to ego dissolution and therapeutic intent was fully mediated by psychological insight. These findings support the predictive self-binding model over the metaphysical belief model.

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

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

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

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

Experimental strategies to discover and develop the next generation of psychedelics and entactogens as medicines

Research on classical psychedelics (psilocybin, LSD and DMT) and entactogen, MDMA, has produced a renaissance in the search for more effective drugs to treat psychiatric, neurological and various peripheral disorders. Psychedelics and entactogens act though interaction with 5-HT_2A and other serotonergic receptors and/or monoamine reuptake transporters. 5-HT, which serves as a neurotransmitter and hormone, is ubiquitously distributed in the brain and peripheral organs, tissues and cells where it has vasoconstrictor, pro-inflammatory and pro-nociceptive actions. Serotonergic psychedelics and entactogens have known safety and toxicity risks. For these drugs, the risks been extensively researched and empirically assessed through human experience. However, novel drug-candidates require thorough non-clinical testing not only to predict clinical efficacy, but also to address the risks they pose during clinical development and later after approval as prescription medicines. We have defined the challenges researchers will encounter when developing novel serotonergic psychedelics and entactogens. We describe screening techniques to predict clinical efficacy and address the safety/toxicity risks emerging from our knowledge of the existing drugs: 1) An early-stage, non-clinical screening cascade to pharmacologically characterise novel drug-candidates. 2) Models to detect hallucinogenic activity. 3) Models to differentiate hallucinogens from entactogens. 4) Non-clinical preclinical lead optimisation technology (PLOT) screening to select drug-candidates. 5) Modified animal models to evaluate the abuse and dependence risks of novel psychedelics in Safety Pharmacology testing. Our intention has been to design non-clinical screening strategies that will reset the balance between benefits and harms to deliver more effective and safer novel psychedelics for clinical use. This article is part of the Special Issue on 'National Institutes of Health Psilocybin Research Speaker Series'.

Contextual Parameters Associated with Positive and Negative Mental Health in Recreational Psychedelic Users

Growing research exploring the utility of psychedelic substances suggests that they not only hold promise for clinical practice but may enhance mental health through recreational use as well. However, given the importance of set and setting for maximizing benefits and minimizing harms of drug use, it is important to develop a foundational understanding of the contextual factors associated with positive and negative mental health in psychedelic users. Accordingly, data were collected using an internet-based survey of psychedelic drug users (n = 511). Hierarchical regression analyses were used to explore to what degree life-time use, frequency of use, dose size, group use, intentions for use, and post-use integration predict mental health in psychedelic users. In particular, using psychedelics with high frequency and to cope with negative affect were found to predict negative mental health. Conversely, using psychedelics in a group setting, with self-expansive intentions, and integrating post-use were found to predict positive mental health. Findings suggest that recreational psychedelic use may either enhance or diminish mental health depending on the contextual parameters of use. Limitations and areas for further research are discussed.

Psilocybin as a Treatment for Psychiatric Illness: A Meta-Analysis

Psilocybin is an emerging potential therapy for the treatment of psychiatric illnesses. Microdosing has been shown to result in an overall improvement in patients with anxiety, depression, obsessive-compulsive disorder, post-traumatic stress disorder, and substance abuse. This meta-analysis explores and compiles prior research to make further inferences regarding psilocybin and its use for the treatment of psychiatric illness along with its safety and efficacy. Database searches were conducted to identify peer-reviewed randomized controlled trials and clinical trials mentioning psilocybin use and psychiatric illness. A Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow diagram was created and analysis was run on the nine articles that met all established inclusion criteria. An event is defined as a participant who showed improvement, in a quantitative method, from baseline after the use of psilocybin. Another analysis was done using depression severity (Quick Inventory of Depressive Symptomatology 16-Item Self Report, QIDS-SR16) at baseline and after the use of psilocybin. Analyses of the original data and the nine articles showed a great deal of heterogeneity with an I² value of 73.68%, suggesting that the studies in this meta-analysis cannot be considered to be studies of the same population. The Q value of 30.4 was higher than 15.507, which is the critical value for eight degrees of freedom found in a chi-square distribution. This Q value showed a high degree of variation and lacked significance. The second meta-run on QIDS-SR16 scores from three studies showed a Q value of 1.16 which was lower than 5.991, the critical value for two degrees of freedom found in a chi-square distribution. The I² statistic for this second meta-analysis was -73% which can be equated to zero. This indicated that the data were homogeneous or that there was no observed heterogeneity. Due to low heterogeneity, the fixed-effects model was used. Based on this meta-analysis, psilocybin seems to show symptom improvement in some psychiatric illnesses. The effectiveness of psilocybin microdosing and the use of psilocybin, in general, need to be studied further to determine the efficacy and safety of potential applications in psychiatry.

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.

Being no one, being One: The role of ego-dissolution and connectedness in the therapeutic effects of psychedelic experience

Background and aims

Despite promising findings indicating the therapeutic potential of psychedelic experience across a variety of domains, the mechanisms and factors affecting its efficacy remain unclear. The present paper explores this by focusing on two psychedelic states which have been suggested as therapeutically significant in past literature: ego-dissolution and connectedness. The aim of the study is to investigate the impact of ego-dissolution and connectedness on the therapeutic effects of the psychedelic experience.

Methods

The investigation was carried out as a mixed methods systematic review, with the data from four databases analysed thematically and results presented through narrative synthesis.

Results

The analysis and synthesis of findings from 15 unique studies (n = 2,182) indicated that both ego-dissolution and connectedness are associated with a higher chance of improvement following a psychedelic experience. However, there seem to be differences in the way the two experiences affect individuals psychologically. Ego-dissolution appears to trigger psychological change but does not typically exceed the psychedelic experience in its duration, while connectedness can be more sustained and is associated with several positive, potentially therapeutic feelings.

Conclusions

Moreover, the findings of this review have implications for further theory-building about the mechanisms which enable therapeutic effects in psychedelic experience. This in turn might lead to improved models for psychedelic therapy practice. Emphasis on ego-dissolution during the preparation phase and on connectedness during integration is one suggestion presented here, alongside overarching implications for the mental health debate and general practice.

Effects of psilocybin versus escitalopram on rumination and thought suppression in depression

BACKGROUND

Major depressive disorder is often associated with maladaptive coping strategies, including rumination and thought suppression.

AIMS

To assess the comparative effect of the selective serotonin reuptake inhibitor escitalopram, and the serotonergic psychedelic psilocybin (COMP360), on rumination and thought suppression in major depressive disorder.

METHOD

Based on data derived from a randomised clinical trial (N = 59), we performed exploratory analyses on the impact of escitalopram versus psilocybin (i.e. condition) on rumination and thought suppression from 1 week before to 6 weeks after treatment inception (i.e. time), using mixed analysis of variance. Condition responder versus non-responder subgroup analyses were also done, using the standard definition of ≥50% symptom reduction.

RESULTS

A time×condition interaction was found for rumination (F(1, 56) = 4.58, P = 0.037) and thought suppression (F(1,57) = 5.88, P = 0.019), with post hoc tests revealing significant decreases exclusively in the psilocybin condition. When analysing via response, a significant time×condition×response interaction for thought suppression (F(1,54) = 8.42, P = 0.005) and a significant time×response interaction for rumination (F(1,54) = 23.50, P < 0.001) were evident. Follow-up tests revealed that decreased thought suppression was exclusive to psilocybin responders, whereas rumination decreased in both responder groups. In the psilocybin arm, decreases in rumination and thought suppression correlated with ego dissolution and session-linked psychological insight.

CONCLUSIONS

These data provide further evidence on the therapeutic mechanisms of psilocybin and escitalopram in the treatment of depression.

Antidepressant effects of a psychedelic experience in a large prospective naturalistic sample

BACKGROUND

Over the last two decades, a number of studies have highlighted the potential of psychedelic therapy. However, questions remain to what extend these results translate to naturalistic samples, and how contextual factors and the acute psychedelic experience relate to improvements in affective symptoms following psychedelic experiences outside labs/clinics. The present study sought to address this knowledge gap.

AIM

Here, we aimed to investigate changes in anxiety and depression scores before versus after psychedelic experiences in naturalistic contexts, and how various pharmacological, extrapharmacological and experience factors related to outcomes.

METHOD

Individuals who planned to undergo a psychedelic experience were enrolled in this online survey study. Depressive symptoms were assessed at baseline and 2 and 4 weeks post-psychedelic experience, with self-rated Quick Inventory of Depressive Symptomatology (QIDS-SR-16) as the primary outcome. To facilitate clinical translation, only participants with depressive symptoms at baseline were included. Sample sizes for the four time points were N = 302, N = 182, N = 155 and N = 109, respectively.

RESULTS

Relative to baseline, reductions in depressive symptoms were observed at 2 and 4 weeks. A medicinal motive, previous psychedelic use, drug dose and the type of acute psychedelic experience (i.e. specifically, having an emotional breakthrough) were all significantly associated with changes in self-rated QIDS-SR-16.

CONCLUSION

These results lend support to therapeutic potential of psychedelics and highlight the influence of pharmacological and non-pharmacological factors in determining response. Mindful of a potential sample and attrition bias, further controlled and observational longitudinal studies are needed to test the replicability of these findings.

Three Naturally-Occurring Psychedelics and Their Significance in the Treatment of Mental Health Disorders

Classical psychedelics represent a family of psychoactive substances with structural similarities to serotonin and affinity for serotonin receptors. A growing number of studies have found that psychedelics can be effective in treating various psychiatric conditions, including post-traumatic stress disorder, major depressive disorder, anxiety, and substance use disorders. Mental health disorders are extremely prevalent in the general population constituting a major problem for the public health. There are a wide variety of interventions for mental health disorders, including pharmacological therapies and psychotherapies, however, treatment resistance still remains a particular challenge in this field, and relapse rates are also quite high. In recent years, psychedelics have become one of the promising new tools for the treatment of mental health disorders. In this review, we will discuss the three classic serotonergic naturally occurring psychedelics, psilocybin, ibogaine, and N, N-dimethyltryptamine, focusing on their pharmacological properties and clinical potential. The purpose of this article is to provide a focused review of the most relevant research into the therapeutic potential of these substances and their possible integration as alternative or adjuvant options to existing pharmacological and psychological therapies.

Predictors and potentiators of psychedelic-occasioned mystical experiences

Mystical experiences are often described as being among the most profound and meaningful events of a person’s life. Their occurrence, while a normal but uncommon phenomenon, is reliably occasioned by psychedelic substances under the appropriate conditions, although care is needed around the context of usage to help ensure safe and beneficial experiences. The occurrence of mystical experiences in psychedelic sessions is a key mediator of the sustained psychological benefits reported in both healthy and clinical populations. Certain factors including set and setting, drug dosage, trait absorption, drug type, intention and states of surrender and acceptance all predict or influence the occurrence of mystical experiences. Various additional factors may further contribute to the occurrence and intensity of mystical experiences and enhance their long-term benefits, including music, meditation and spiritual practices and nature-based settings. This review examines these factors and considers how they might be optimised to increase the chances of a mystical experience occurring, while also considering factors that are negatively associated with mystical experiences with suggestions on how these might be mitigated where applicable. Finally, potential future research avenues for furthering our knowledge of psychedelic mystical experiences and how their benefits might be enhanced is suggested. Maximising the potential for the occurrence of mystical experiences is an important aspect of the beneficial application of psychedelics.

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.

Perceptions of safety, subjective effects, and beliefs about the clinical utility of lysergic acid diethylamide in healthy participants within a novel intervention paradigm: Qualitative results from a proof-of-concept study

BACKGROUND

Classic psychedelics show promise in the treatment of mental health conditions; however, more scalable intervention protocols are needed to maximize access to these novel therapeutics. In this proof-of-concept study, perceptions of safety, subjective effects, and beliefs about the clinical utility of lysergic acid diethylamide (LSD) were evaluated among healthy participants (N = 31) administered 50 to 100 µg LSD in a treatment paradigm conceptualized as more scalable than traditional approaches to administering classic psychedelics.

METHODS

Semi-structured interviews assessed participants' expectations, experience, and thoughts on the safety and efficacy of the study design. These interviews were transcribed for thematic analysis relating to perceptions of safety, subjective effects, and beliefs about the clinical utility of LSD.

RESULTS

Most participants felt safe throughout the study, with a minority reporting concerns related to having a challenging experience that diminished over time. Participants attributed their feelings of safety to the study structure and support of their attendants, which allowed them to "let go" and immerse themselves in the experience without pre-occupation. Furthermore, participants reported transcendent, mystical-type experiences characteristic of classic psychedelics, with almost half highlighting the prominent role played by music during the acute period of drug action. Finally, participants endorsed support for the clinical utility of LSD in controlled environments, expressing the belief that LSD is safe and has the potential to help others.

CONCLUSION

Findings provide preliminary support for the feasibility of this scalable interventional paradigm and set the stage for future critical research with clinical populations.

Evaluating the Potential Use of Serotonergic Psychedelics in Autism Spectrum Disorder

Recent clinical and preclinical evidence points towards empathogenic and prosocial effects elicited by psychedelic compounds, notably the serotonin 5-HT_2A agonists lysergic acid diethylamide (LSD), psilocybin, N,N-Dimethyltryptamine (DMT), and their derivatives. These findings suggest a therapeutic potential of psychedelic compounds for some of the behavioural traits associated with autism spectrum disorder (ASD), a neurodevelopmental condition characterized by atypical social behaviour. In this review, we highlight evidence suggesting that psychedelics may potentially ameliorate some of the behavioural atypicalities of ASD, including reduced social behaviour and highly co-occurring anxiety and depression. Next, we discuss dysregulated neurobiological systems in ASD and how they may underlie or potentially limit the therapeutic effects of psychedelics. These phenomena include: 1) synaptic function, 2) serotonergic signaling, 3) prefrontal cortex activity, and 4) thalamocortical signaling. Lastly, we discuss clinical studies from the 1960s and 70s that assessed the use of psychedelics in the treatment of children with ASD. We highlight the positive behavioural outcomes of these studies, including enhanced mood and social behaviour, as well as the adverse effects of these trials, including increases in aggressive behaviour and dissociative and psychotic states. Despite preliminary evidence, further studies are needed to determine whether the benefits of psychedelic treatment in ASD outweigh the risks associated with the use of these compounds in this population, and if the 5-HT_2A receptor may represent a target for social-behavioural disorders.

The clinical pharmacology and potential therapeutic applications of 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT)

5‐methoxy‐N,N‐dimethyltryptamine (5‐MeO‐DMT) is a naturally occurring tryptamine that primarily acts as an agonist at the 5‐HT1A and 5‐HT2A receptors, whereby affinity for the 5‐HT1A subtype is highest. Subjective effects following 5‐MeO‐DMT administration include distortions in auditory and time perception, amplification of emotional states, and feelings of ego dissolution that usually are short‐lasting, depending on the route of administration. Individual dose escalation of 5‐MeO‐DMT reliably induces a “peak” experience, a state thought to be a core predictor of the therapeutic efficacy of psychedelics. Observational studies and surveys have suggested that single exposure to 5‐MeO‐DMT can cause rapid and sustained reductions in symptoms of depression, anxiety, and stress. 5‐MeO‐DMT also stimulates neuroendocrine function, immunoregulation, and anti‐inflammatory processes, which may contribute to changes in mental health outcomes. To date, only one clinical trial has been published on 5‐MeO‐DMT, demonstrating the safety of vaporized dosing up to 18 mg. Importantly, the rapid onset and short duration of the 5‐MeO‐DMT experience may render it more suitable for individual dose‐finding strategies compared with longer‐acting psychedelics. A range of biotech companies has shown an interest in the development of 5‐MeO‐DMT formulations for a range of medical indications, most notably depression. Commercial development will therefore be the most important resource for bringing 5‐MeO‐DMT to the clinic. However, fundamental research will also be needed to increase understanding of the neurophysiological and neural mechanisms that contribute to the potential clinical effects of 5‐MeO‐DMT and its sustainability and dissemination over time. Such studies are less likely to be conducted as part of drug development programs and are more likely to rely on independent, academic initiatives.

Prefrontal contributions to the stability and variability of thought and conscious experience

The human prefrontal cortex is a structurally and functionally heterogenous brain region, including multiple subregions that have been linked to different large-scale brain networks. It contributes to a broad range of mental phenomena, from goal-directed thought and executive functions to mind-wandering and psychedelic experience. Here we review what is known about the functions of different prefrontal subregions and their affiliations with large-scale brain networks to examine how they may differentially contribute to the diversity of mental phenomena associated with prefrontal function. An important dimension that distinguishes across different kinds of conscious experience is the stability or variability of mental states across time. This dimension is a central feature of two recently introduced theoretical frameworks-the dynamic framework of thought (DFT) and the relaxed beliefs under psychedelics (REBUS) model-that treat neurocognitive dynamics as central to understanding and distinguishing between different mental phenomena. Here, we bring these two frameworks together to provide a synthesis of how prefrontal subregions may differentially contribute to the stability and variability of thought and conscious experience. We close by considering future directions for this work.

Medicinal psychedelics for mental health and addiction: Advancing research of an emerging paradigm

The medical use of psychedelic substances (e.g. psilocybin, ayahuasca, lysergic acid diethylamide and 3,4-methylenedioxymethamphetamine) is attracting renewed interest, driven by a pressing need for research and development of novel therapies for psychiatric disorders, as well as promising results of contemporary studies. In this Viewpoint, we reflect upon the 'Clinical Memorandum on Psychedelics' recently released by the Royal Australian and New Zealand College of Psychiatrists and note subsequent developments including the application for down-scheduling of psilocybin and 3,4-methylenedioxymethamphetamine presently being considered by the Therapeutic Goods Administration and approvals for access via the Special Access Scheme. We suggest that this field is worthy of rigorous research to assess potential benefits, address safety parameters and clarify therapeutic mechanisms. To this end, we outline recent research findings, provide an overview of current knowledge relating to mechanisms of action and discuss salient aspects of the psychedelic-assisted psychotherapy treatment model. The sum of this research points towards medicinal psychedelics as a potential new class of psychiatric treatments when used within a medically supervised framework with integrated psychotherapeutic support. However, before widespread translation into clinical use can occur, appropriately designed and sufficiently powered trials are required to detect both potential positive and negative outcomes. Unique safety and regulatory challenges also need to be addressed. As for any new medical therapy, psychedelic research needs to be conducted in a rigorous manner, through the dispassionate lens of scientific enquiry. Carte blanche availability to practitioners, without specific protocols and appropriate training, would be potentially harmful to individuals and detrimental to the field.

Cannabis-induced oceanic boundlessness

BACKGROUND

Despite tetrahydrocannabinol (THC)'s reputation for creating dramatic effects at high doses, empirical work rarely addresses cannabis's impact on subjective responses common to the tryptamine psychedelics. We focused on these effects because they have preceded and covaried with the therapeutic impact of psilocybin in previous work.

AIMS

The current study examined if self-reported responses to cannabis products might parallel those found in clinical trials of psilocybin administration. We also investigated if measures of demographics and cannabis use might correlate with these responses.

METHODS

Participants reported the subjective effect of their highest THC experience using 27 items that assess oceanic boundlessness, a correlate of mystical experiences. They also answered infrequency items and questions on demographics and cannabis consumption.

RESULTS

In an effort to address concerns about replication, we divided respondents who passed infrequency items into two random samples. Self-reported "breakthrough" experiences were significantly greater than zero but significantly lower than those reported in randomized clinical trials of psilocybin (17-19% vs. 59%). Total scores covaried with perceived dosages of THC, but only in one sample. Heavier users of cannabis reported lower scores.

CONCLUSIONS

Self-report data suggest that high doses of cannabis can create subjective effects comparable to those identified in trials of psilocybin that precede relief from cancer-related distress, treatment-resistant depression, alcohol problems, and cigarette dependence. Given the disparate mechanisms of action, comparing THC-induced to psilocybin-induced effects might improve our understanding of the mechanisms underlying subjective experiences. This work might also support the development of a cannabis-assisted psychotherapy comparable to psilocybin-assisted psychotherapy.

Four individuals' experiences during and following a psilocybin truffle retreat in the Netherlands

This article reports on the experiences of four healthy individuals who attended a legal psilocybin truffle retreat in the Netherlands. The study employed a qualitative phenomenological approach, using semi-structured interviews to gain an understanding of participants' psilocybin experiences and their after-effects. The experiential themes that emerged from these case studies closely match themes that have been identified in previous studies of psilocybin, including variability of the experience, the presence of mystical-type features, significant changes to subjective sense of self, and a generalized sense of connectedness. Participants framed their narrative accounts around moments of key insight, and these insights were related to a sense of connection: to self, others, and to a broader relational ontology. Embodiment, currently an understudied topic in psychedelic research, also emerged as a theme. The case studies presented here provide preliminary evidence to suggest that for healthy individuals in a well-controlled and supportive retreat setting, a high dose of psilocybin can lead to enduring positive after-effects that last up to twelve months.

Clinical and biological predictors of psychedelic response in the treatment of psychiatric and addictive disorders: A systematic review

BACKGROUND

The use of psychedelic treatments has shown very promising results in some psychiatric and addictive disorders, but not all patients achieved a response.

AIM

The aim of this review is to explore the clinical and biological factors which could predict the response to psychedelics in psychiatric and addictive disorders.

METHODS

A systematic research was performed on MEDLINE, PsycInfo, Web of science, and Scopus databases from January 1990 to May 2020. All studies investigating the predictive factors of response to psychedelics regardless of psychiatric or addictive disorders, were included.

RESULTS

Twenty studies investigating addictive disorder, treatment-resistant depression, obsessive-compulsive disorder and depressive and anxiety symptoms in patients with life-threatening cancer were included in this review. We found that, in all indications, the main predictive factor of response to psychedelics is the intensity of the acute psychedelic experience. Indeed, we found this factor for alcohol and tobacco use disorders, treatment-resistant depression, and anxiety and depressive symptoms in patients with life-threatening cancer, but not for obsessive-compulsive disorder.

CONCLUSION

The intensity of the acute psychedelic experience was the main predicting factor of response. The action mechanism of this experience was not clear, but some hypotheses could be made, such as a modulation of serotoninergic system by 5-HT2A receptors agonism, a modulation of the default mode network (DMN) with an acute modular disintegration of the DMN followed by a re-integration of this network with a normal functioning, or an anti-inflammatory effect of this treatment.

Predicting Reactions to Psychedelic Drugs: A Systematic Review of States and Traits Related to Acute Drug Effects

Psychedelic drugs are increasingly being incorporated into therapeutic contexts for the purposes of promoting mental health. However, they can also induce adverse reactions in some individuals, and it is difficult to predict before treatment who is likely to experience positive or adverse acute effects. Although consideration of setting and dosage as well as excluding individuals with psychotic predispositions has thus far led to a high degree of safety, it is imperative that researchers develop a more nuanced understanding of how to predict individual reactions. To this end, the current systematic review coalesced the results of 14 studies that included baseline states or traits predictive of the acute effects of psychedelics. Individuals high in the traits of absorption, openness, and acceptance as well as a state of surrender were more likely to have positive and mystical-type experiences, whereas those low in openness and surrender or in preoccupied, apprehensive, or confused psychological states were more likely to experience acute adverse reactions. Participant sex was not a robust predictor of drug effects, but 5-HT2AR binding potential, executive network node diversity, and rACC volume may be potential baseline biomarkers related to acute reactions. Finally, increased age and experience with psychedelics were individual differences related to generally less intense effects, indicating that users may become slightly less sensitive to the effects of the drugs after repeated usage. Although future well-powered, placebo-controlled trials directly comparing the relative importance of these predictors is needed, this review synthesizes the field's current understanding of how to predict acute reactions to psychedelic drugs.

Dose-response relationships of psilocybin-induced subjective experiences in humans

BACKGROUND

Psilocybin is the psychoactive component in Psilocybe mushrooms ('magic mushrooms'). Whether and how the quality of the psilocybin-induced experience might mediate beneficial health outcomes is currently under investigation, for example, in therapeutic applications. However, to date, no meta-analysis has investigated the dose-dependency of subjective experiences across available studies.

AIM

Establishing dose-response relationships of the subjective experiences induced by psilocybin in healthy study participants and a comparison of patient groups.

METHOD

We applied a linear meta-regression approach, based on the robust variance estimation framework, to obtain linear dose-response relationship estimates on questionnaire ratings after oral psilocybin administration. Data were obtained from the Altered States Database, which contains data extracted from MEDLINE-listed journal articles that used standardized and validated questionnaires: the Altered States of Consciousness Rating Scale, the Mystical Experience Questionnaire and the Hallucinogen Rating Scale.

RESULTS

Psilocybin dose positively correlated with ratings on most factors and scales, mainly those referring to perceptual alterations and positively experienced ego dissolution. Measures referring to challenging experiences exhibited small effects and were barely modulated by dose.

CONCLUSION

Psilocybin intensified almost all characteristics of altered states of consciousness assessed with the given questionnaires. Because subjective experiences are not only determined by dose, but also by individual and environmental factors, the results may only apply to controlled laboratory experiments and not to recreational use. This paper may serve as a general literature citation for the use of psilocybin in experimental and clinical research, to compare expected and observed subjective experiences.

Psychedelic Harm Reduction and Integration: A Transtheoretical Model for Clinical Practice

Psychedelic Harm Reduction and Integration (PHRI) is a transtheoretical and transdiagnostic clinical approach to working with patients who are using or considering using psychedelics in any context. The ongoing discussion of psychedelics in academic research and mainstream media, coupled with recent law enforcement deprioritization of psychedelics and compassionate use approvals for psychedelic-assisted therapy, make this model exceedingly timely. Given the prevalence of psychedelic use, the therapeutic potential of psychedelics, and the unique cultural and historical context in which psychedelics are placed, it is important that mental health providers have an understanding of the unique motivations, experiences, and needs of people who use them. PHRI incorporates elements of harm reduction psychotherapy and psychedelic-assisted psychotherapy, and can be applied in both brief and ongoing psychotherapy interactions. PHRI represents a shift away from assessment limited to untoward outcomes of psychedelic use and abstinence-based addiction treatment paradigms and toward a stance of compassionate, destigmatizing acceptance of patients' choices. Considerations for assessment, preparation, and working with difficult experiences are presented.

Self-Medication for Chronic Pain Using Classic Psychedelics: A Qualitative Investigation to Inform Future Research

Background: Chronic Pain is among the leading causes of disability worldwide with up to 60% of patients suffering from comorbid depression. Psychedelic-assisted therapy has recently been found effective in treating a host of mental health issues including depression and has historically been found to be useful in treating pain. Reports of self-medication for chronic pain using psychedelic drugs have been widely documented, with anecdotal evidence indicating widespread success in a range of pathologies. Aims: In preparation for an upcoming trial, to better understand how those with lived experience of chronic pain self-medicate with psychedelic drugs, and to establish, in detail, their therapeutic protocols and practices for success. Methods: As part of patient-involvement (PI) for an upcoming trial in this population, 11 individuals who reported self-medicating with psychedelic drugs took part in a 1-h semi-structured discussion, which was then transcribed and thematically analyzed. Results: Across a range of psychedelic substances and doses, reported pain scores improved substantially during and after psychedelic experiences. Two processes, Positive Reframing and Somatic Presence, were reliably identified as playing a role in improvements in mental wellbeing, relationship with pain, and physical (dis)comfort. Inclusion of other strategies such as mindfulness, breathwork, and movement were also widely reported. Due to the data's subjective nature, this paper is vulnerable to bias and makes no claims on causality or generalisability. Together, these results have been used to inform study design for a forthcoming trial. Conclusion: This pre-trial PI work gives us confidence to test psychedelic therapy for chronic pain in a forthcoming controlled trial. The results presented here will be instrumental in improving our ability to meet the needs of future study participants.

Does Psychedelic Therapy Have a Transdiagnostic Action and Prophylactic Potential?

Addressing global mental health is a major 21st-century challenge. Current treatments have recognized limitations; in this context, new ones that are prophylactic and effective across diagnostic boundaries would represent a major advance. The view that there exists a core of transdiagnostic overlap between psychiatric disorders has re-emerged in recent years, and evidence that psychedelic therapy holds promise for a range of psychiatric disorders supports the position that it may be transdiagnostically effective. Here, we propose that psychedelic therapy's core, transdiagnostically relevant action lies in its ability to increase neuronal and mental plasticity, thus enhancing the potential for change, which we consider to be a key to its therapeutic benefits. Moreover, we suggest that enhanced plasticity via psychedelics, combined with a psychotherapeutic approach, can aid healthy adaptability and resilience, which are protective factors for long-term well-being. We present candidate neurological and psychological markers of this plasticity and link them with a predictive processing model of the action of psychedelics. We propose that a model of psychedelic-induced plasticity combined with an adequate therapeutic context has prophylactic and transdiagnostic potential, implying that it could have a broad, positive impact on public health.

Psilocybin occasioned mystical-type experiences

OBJECTIVE

Research into psychedelic therapy models has shown promise for the treatment of specific psychiatric conditions. Mystical-type experiences occasioned by psilocybin have been correlated with therapeutic benefits and long-term improvements in positive mental outlook and attitudes. This article aims to provide an overview of the topic, highlight strengths and weaknesses in current research, generate novel perspectives and discussion, and consider future avenues for research.

DESIGN

This narrative review was designed to summarise and assess the state of research on psilocybin occasioned mystical-type experiences and applications for the treatment of specific psychiatric conditions.

RESULTS

Contemporary methods on the quantification of mystical-type experiences and their acute subjective effects are discussed. Recent studies provide some understanding of the pharmacological actions of psychedelics although the neurological similarities and differences between spontaneous and psychedelic mystical-type experiences are not well described. Applicability to modern clinical settings is assessed. Potential novel therapeutic applications include use in positive psychology interventions in healthy individuals.

CONCLUSIONS

Since 2006 significant advancements in understanding the therapeutic potential of psilocybin-assisted psychotherapy have been made; however, more work is required to understand the neuromechanistic processes and applicability in modern clinical settings. Despite promising results in recent studies, funding issues for clinical trials, legal concerns and socio-cultural resistance provide a counterpoint to experimental evidence.

Psychedelics and virtual reality: parallels and applications

Psychedelic drugs and virtual reality (VR) each have the capacity to disrupt the rigidity and limitations of typical conscious experience. This article delineates the parallels among psychedelic and VR states as well as their potential synergistic applications in clinical and recreational settings. Findings indicate that, individually, psychedelics and VR are used in analogous ways to alter sensory experience and evoke awe. They are also both used in tandem with traditional therapies to treat a variety of mood disorders; their shared capacity to transiently alter perspective and disrupt rigid patterns of mental experience may underly their analogous and transdiagnostic therapeutic uses. In terms of their combined applications, a number of recreational users currently utilize psychedelics and VR together to enhance their experience. We propose that VR may be a useful tool for preparing hallucinogen-naïve participants in clinical trials for the sensory distortions experienced in psychedelic states. Given the critical role of "setting" in psychedelic treatment outcomes, we also detail how VR could be used to optimize the environment in psychedelic sessions. Finally, we provide considerations for future studies and detail how advancements in psychedelic and VR research can inform one another. Collectively, this article outlines a number of connections between psychedelics and VR, and, more broadly, is representative of growing scientific interest into the interactions among technology, psychopharmacology, and mental health.

Learning to Let Go: A Cognitive-Behavioral Model of How Psychedelic Therapy Promotes Acceptance

The efficacy of psychedelic-assisted therapies for mental disorders has been attributed to the lasting change from experiential avoidance to acceptance that these treatments appear to facilitate. This article presents a conceptual model that specifies potential psychological mechanisms underlying such change, and that shows substantial parallels between psychedelic therapy and cognitive behavioral therapy: We propose that in the carefully controlled context of psychedelic therapy as applied in contemporary clinical research, psychedelic-induced belief relaxation can increase motivation for acceptance via operant conditioning, thus engendering episodes of relatively avoidance-free exposure to greatly intensified private events. Under these unique learning conditions, relaxed avoidance-related beliefs can be exposed to corrective information and become revised accordingly, which may explain long-term increases in acceptance and corresponding reductions in psychopathology. Open research questions and implications for clinical practice are discussed.