Psychometric evaluation of the altered states of consciousness rating scale (OAV)

Probing the functional magnetic resonance imaging response to psilocybin in functional neurological disorder (PsiFUND): study protocol

Background

Functional neurological disorder (FND) is a common cause of neurological symptoms including seizures and movement disorders. It can be debilitating, is associated with high health and social care costs, and can have a poor prognosis. Functional magnetic resonance imaging (fMRI) has suggested FND is a multi-network disorder. Converging evidence suggests that other mechanisms including dissociation, interoception, and motor agency may be abnormal in people with FND. Psychedelics are currently under investigation for numerous neuropsychiatric disorders and have been shown to disrupt functional brain networks. Administering psychedelics to people with FND will help us to probe mechanistic theories of the disorder.

Protocol

In this open-label neuroimaging study, we will administer 25mg oral psilocybin with psychological support to people with chronic FND (target n = 24). Participants will undergo resting-state and task-based (Libet's clock, a measure of motor agency) fMRI sequences which will be compared in a pre-post manner. Additional mechanistic outcomes including measures of interoception (heartbeat tracking task), somatisation, illness perceptions, suggestibility, and dissociation will be collected. Data on expectancy, preparedness, and subjective experience of the psychedelic experience will also be gathered. Participants will be followed up for three months following psilocybin administration. fMRI changes in networks will be analysed using seed-based approaches, and additional exploratory analysis of resting-state imaging will take place.

Discussion

The study will help us to probe the mechanisms thought to potentially underpin FND. As the first modern study of psychedelics in FND, it will also help us to understand whether psychedelic administration alongside psychological support might be safe and feasible in this patient population.

Exploring 5-MeO-DMT as a pharmacological model for deconstructed consciousness

5-MeO-DMT is a short-acting psychedelic that is anecdotally reported to induce a radical disruption of the self and a paradoxical quality of aroused, waking awareness that is nevertheless devoid of any specific perceptual contents. Here, we conducted an exploratory observational study of the phenomenological and neuronal effects of this compound. We collected micro-phenomenological interviews, psychometric questionnaires, and electroencephalography (EEG) in naturalistic ceremonial settings where 5-MeO-DMT was ingested. Results revealed that the 5-MeO-DMT experience followed a dynamic progression that-only in the most extreme cases-manifested as a complete absence of self-experience and other phenomenal content with preserved awareness. Furthermore, visual imagery, bodily self-disruption, narrative self-disruption, and reduced phenomenal distinctions occurred in a variable fashion. EEG analyses revealed the 5-MeO-DMT experience was characterised by (global) alpha and (posterior) beta power reductions, implying a mode of brain functioning where top-down models are inhibited. Our preliminary phenomenological findings confirm the potential utility of 5-MeO-DMT as a pharmacological model for deconstructed consciousness while noting the limitations of employing retrospective questionnaires for this purpose. Considering the exploratory nature of this study and its limitations inherent to its naturalistic nature, further research employing real-time experience sampling and phenomenologically trained participants in controlled environments could expand our findings to meaningfully inform the potential of this tool for the scientific study of consciousness.

Decreased CO2 saturation during circular breathwork supports emergence of altered states of consciousness

Altered states of consciousness (ASCs), induced e.g. during psychedelic-assisted therapy, show potential to treat prevalent mental health disorders like depression and posttraumatic stress disorder. However, access to such treatments is restricted by legal, medical, and financial barriers. Circular breathwork may present a non-pharmacological and hence more accessible alternative to engage similar therapeutic processes. Scientific studies of breathwork are only just emerging and its physiological and psychological mechanisms are largely unknown. Here, we track physiological and experiential dynamics throughout a breathwork session, comparing two forms of breathwork: Holotropic and Conscious-Connected breathwork. We show that a reduction in end-tidal CO2 pressure due to deliberate hyperventilation is significantly correlated to ASC onset (r = -0.46; p < 0.001). Based on standard questionnaires (MEQ-30 and 11-DASC), the ASCs evoked by breathwork resembled those produced by psychedelics across several experiential domains such as ego dissolution, and their depth predicted psychological and physiological follow-on effects, including improved well-being and reduced depressive symptoms. Further analysis showed that different breathwork approaches produced highly similar outcomes. Our findings identify physiological boundary conditions for ASCs to arise in a non-pharmacological context, shedding light on the functional mechanisms of breathwork as well as its potential as a psychotherapeutic tool.

The strength of neural entrainment to electronic music correlates with proxies of altered states of consciousness

In electronic music events, the driving four-on-the-floor music appears pivotal for inducing altered states of consciousness (ASCs). While various physiological mechanisms link repetitive auditory stimuli to ASCs, entrainment-a brainwave synchronization through periodic external stimuli-has garnered primary focus. However, there are no studies systematically exploring the relationship between entrainment and ASCs. In the present study, we depart from the finding that entrainment to auditory stimuli peaks for stimulation rates around 2 Hz compared to others. Nineteen participants listened to six one-minute electronic music excerpts at different tempos (1.65 Hz, 2.25 Hz, and 2.85 Hz). For each excerpt, they performed cognitive tasks and reported phenomenological experiences related to ASCs through questionnaires. Brain activity was recorded with electroencephalography to assess whether a modulation in entrainment by the beat of electronic music affected objective and subjective proxies of ASCs. Our results revealed a tempo-driven modulation of entrainment at the group level, with entrainment being higher for stimulation rates at 1.65 Hz compared to 2.85 Hz. Similarly, music at 1.65 Hz aroused more feelings of unity compared to music at 2.85 Hz. However, at the individual level, no significant relationship was found between entrainment magnitude and phenomenological experience. Instead, a positive relationship was observed between entrainment and participants' reaction time. The results suggest that brainwave entrainment modulate processes relevant to rhythm-induced ASCs. While we cannot determine whether participants entered an ASC due to design constraints, the observed relationship between entrainment and reaction time at the individual level supports its functional significance.

Music mindfulness acutely modulates autonomic activity and improves psychological state in anxiety and depression

Introduction

Anxiety and depression reduce autonomic system activity, as measured by Heart Rate Variability (HRV), and exacerbate cardiac morbidity. Both music and mindfulness have been shown to increase HRV, and clinical approaches incorporating these interventions show promise as effective treatments for symptoms of anxiety and depression. Music mindfulness, which combines music listening with mindfulness activities, may provide unique and synergistic therapeutic benefits for stress management. However, to date, no studies have evaluated the physiological mechanisms underlying a community-based music mindfulness paradigm.

Methods

We used wearable technology to record electrocardiography and electroencephalography signals from participants with moderate symptoms of anxiety and depression during a community-based music mindfulness paradigm. We also assessed the impact of our music mindfulness session on participant's psychological state.

Results and discussion

We found that music mindfulness sessions acutely enhanced multiple measures of HRV and altered EEG power spectral density across various frequency bands in frontotemporal electrodes. Both live and virtual music mindfulness sessions also acutely reduced stress and altered participants' state of consciousness; however, only live sessions fostered social connection. Additionally, the physiological and psychological effects of music mindfulness varied based on participants' self-reported sex. Overall, our findings demonstrate that music mindfulness effectively engages autonomic and frontotemporal neural mechanisms, which may contribute to the treatment of anxiety and depression symptoms.

Psilocybin-assisted therapy for relapse prevention in alcohol use disorder: a phase 2 randomized clinical trial

Background

Despite the promising therapeutic effects of psilocybin, its efficacy in preventing relapse after withdrawal treatment for alcohol use disorder (AUD) remains unknown. This study aims to assess whether a single dose of psilocybin combined with brief psychotherapy could reduce relapse rates and alcohol use in AUD patients.

Methods

This single-center, double-blind, randomized clinical trial was conducted in Switzerland. We recruited participants with AUD between June 8, 2020, and August 16, 2023 who completed withdrawal treatment within six weeks prior to enrollment. Participants were randomized (1:1) to receive either a single oral dose of psilocybin (25 mg) or placebo (mannitol), combined with brief psychotherapy. The primary outcomes were abstinence and mean alcohol use at 4-week follow-up. Participants completed the timeline followback to assess daily alcohol use. The trial is registered on ClinicalTrials.gov (NCT04141501).

Findings

We included 37 participants who completed the 4-week follow-up (female:male = 14:23; psilocybin = 18, placebo = 19) in the analysis. There were no significant differences between groups in abstinence duration (p = 0.55, psilocybin mean = 16.80 days, 95% CI: 14.31-19.29; placebo mean = 13.80 days, 95% CI: 10.97-16.63; Cohen's d = 0.151) or mean alcohol use per day (p = 0.51, psilocybin: median = 0.48 standard alcohol units, range: 0-3.99, placebo: median = 0.54 standard alcohol units, range: 0-5.96; Cohen's d = 0.11) at 4-week or 6-month follow-up (abstinence: Cohen's d = 0.10, alcohol use: Cohen's d = 0.075). Participants in both groups reported reduced craving and temptation to drink alcohol after the dosing visit, with an additional reduction observed in the psilocybin group. Thirteen adverse events occurred in the psilocybin and seven in the placebo group. One serious adverse event occurred in the psilocybin and four in the placebo group, all related to inpatient withdrawal treatments.

Interpretation

A single dose of psilocybin combined with five psychotherapy sessions may not be sufficient to reduce relapse rates and alcohol use in severely affected AUD patients following withdrawal treatment. However, given the limited sample size of our study, larger trials are needed in the future to confirm these findings.

Funding

Swiss National Science Foundation under the framework of Neuron Cofund, Swiss Neuromatrix Foundation, and Heffter Young Investigator Fellowship Award.

Connectome harmonic decomposition tracks the presence of disconnected consciousness during ketamine-induced unresponsiveness

BACKGROUND

Ketamine, in doses suitable to induce anaesthesia in humans, gives rise to a unique state of unresponsiveness accompanied by vivid experiences and sensations, making it possible to disentangle the correlated but distinct concepts of conscious awareness and behavioural responsiveness. This distinction is often overlooked in the study of consciousness.

METHODS

The mathematical framework of connectome harmonic decomposition (CHD) was used to view functional magnetic resonance imaging (fMRI) signals during ketamine-induced unresponsiveness as distributed patterns across spatial scales. The connectome harmonic signature of this particular state was mapped onto signatures of other states of consciousness for comparison.

RESULTS

An increased prevalence of fine-grained connectome harmonics was found in fMRI signals obtained during ketamine-induced unresponsiveness, indicating higher granularity. After statistical assessment, the ketamine sedation harmonic signature showed alignment with signatures of LSD-induced (fixed effect =0.0113 [0.0099, 0.0127], P<0.001) or ketamine-induced (fixed effect =0.0087 [0.0071, 0.0103], P<0.001) psychedelic states, and misalignment with signatures seen in unconscious individuals owing to propofol sedation (fixed effect =-0.0213 [-0.0245, -0.0181], P<0.001) or brain injury (fixed effect =-0.0205 [-0.0234, -0.0178], P<0.001).

CONCLUSIONS

The CHD framework, which only requires resting-state fMRI data and can be applied retrospectively, has the ability to track alterations in conscious awareness in the absence of behavioural responsiveness on a group level. This is possible because of ketamine's unique property of decoupling these two facets, and is important for consciousness and anaesthesia research.

Neural mechanisms of psychedelic visual imagery

Visual alterations under classic psychedelics can include rich phenomenological accounts of eyes-closed imagery. Preclinical evidence suggests agonism of the 5-HT2A receptor may reduce synaptic gain to produce psychedelic-induced imagery. However, this has not been investigated in humans. To infer the directed connectivity changes to visual connectivity underlying psychedelic visual imagery in healthy adults, a double-blind, randomised, placebo-controlled, cross-over study was performed, and dynamic causal modelling was applied to the resting state eyes-closed functional MRI scans of 24 subjects after administration of 0.2 mg/kg of the serotonergic psychedelic drug, psilocybin (magic mushrooms), or placebo. The effective connectivity model included the early visual area, fusiform gyrus, intraparietal sulcus, and inferior frontal gyrus. We observed a pattern of increased self-inhibition of both early visual and higher visual-association regions under psilocybin that was consistent with preclinical findings. We also observed a pattern of reduced inhibition from visual-association regions to earlier visual areas that indicated top-down connectivity is enhanced during visual imagery. The results were analysed with behavioural measures taken immediately after the scans, suggesting psilocybin-induced decreased sensitivity to neural inputs is associated with the perception of eyes-closed visual imagery. The findings inform our basic and clinical understanding of visual perception. They reveal neural mechanisms that, by affecting balance, may increase the impact of top-down feedback connectivity on perception, which could contribute to the visual imagery seen with eyes-closed during psychedelic experiences.

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

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

Prediction of hallucinogen persisting perception disorder and thought disturbance symptoms following psychedelic use

Interest in using psychedelic drugs to treat psychiatric disorders is growing rapidly. While modern controlled clinical trials show a favorable safety and efficacy profile, it remains unclear if the risk of side effects would increase with broader use in more heterogeneous populations. To address this, we investigated the frequency and baseline predictors of delusional ideation, magical thinking, and "hallucinogen persisting perception disorder" (HPPD)-related symptoms following psychedelic use in a self-selected naturalistic sample. Using a prospective cohort study, symptoms were assessed in ( N = 654 ) participants at one week before a planned psychedelic experience, and at two and four weeks afterward. Across the sample, delusional ideation was found to be reduced one month after psychedelic use ( P < 0.001 ) with no changes detected in magical thinking. These findings were in seeming opposition to positive correlations between lifetime psychedelic use at baseline with magical thinking ( r s = 0.12 , P = 0.003 ) and delusional ideation ( r s = 0.11 , P = 0.01 ), suggesting that schizotypal traits, instead of being caused by, may merely correlate with psychedelic use. Importantly, over 30% of the sample reported HPPD-type effects at the 4-week endpoint, although rarely perceived as distressing (< 1% of the population). Younger age, female gender, history of a psychiatric diagnosis and baseline trait absorption predicted the occurrence of HPPD-like effects. This is in line with prior studies showing a high prevalence of HPPD-like symptoms in psychedelic users, which, however, appear to remain at a subclinical severity in most cases, explaining the comparatively lower prevalence of HPPD diagnoses.

Experience after Floatation-REST: Relaxation during floating mediates the afterglow effect

The term "afterglow" originally described the heightened mood and relaxation following psychedelics and later extended to other altered states. Despite anecdotal reports, little research has explored this effect, especially in Floatation-REST (Reduced Environmental Stimulation Technique). In this method, individuals float in thermoneutral, supersaturated salt water in a dark, quiet tank. Using a crossover design, 34 participants (17 females, 17 males; avg. age 32.2, SD = 8.8) were randomized to 60 min of Floatation-REST or Bed-REST (a control condition on a waterbed). Floatation-REST induced significantly weaker body boundaries, significantly stronger time distortion, and significantly greater relaxation. Post-exposure, participants reported a significantly stronger afterglow, significantly more state mindfulness, and significantly greater interoceptive awareness. Mediation analysis showed relaxation during floating fully explains the afterglow effect. These findings align with psychedelic research, suggesting Floatation-REST elicits similar effects and laying the groundwork for future studies on prolonged afterglow experiences.

Psychedelic Drugs in Mental Disorders: Current Clinical Scope and Deep Learning-Based Advanced Perspectives

Mental disorders are a representative type of brain disorder, including anxiety, major depressive depression (MDD), and autism spectrum disorder (ASD), that are caused by multiple etiologies, including genetic heterogeneity, epigenetic dysregulation, and aberrant morphological and biochemical conditions. Psychedelic drugs such as psilocybin and lysergic acid diethylamide (LSD) have been renewed as fascinating treatment options and have gradually demonstrated potential therapeutic effects in mental disorders. However, the multifaceted conditions of psychiatric disorders resulting from individuality, complex genetic interplay, and intricate neural circuits impact the systemic pharmacology of psychedelics, which disturbs the integration of mechanisms that may result in dissimilar medicinal efficiency. The precise prescription of psychedelic drugs remains unclear, and advanced approaches are needed to optimize drug development. Here, recent studies demonstrating the diverse pharmacological effects of psychedelics in mental disorders are reviewed, and emerging perspectives on structural function, the microbiota-gut-brain axis, and the transcriptome are discussed. Moreover, the applicability of deep learning is highlighted for the development of drugs on the basis of big data. These approaches may provide insight into pharmacological mechanisms and interindividual factors to enhance drug discovery and development for advanced precision medicine.

Safety and Efficacy of Repeated Low-Dose LSD for ADHD Treatment in Adults: A Randomized Clinical Trial

Importance

Microdosing psychedelics, including lysergic acid diethylamide (LSD), has gained attention for its potential benefits in several psychiatric disorders, including attention-deficit/hyperactivity disorder (ADHD). However, LSD's efficacy in reducing ADHD symptoms remains unknown.

Objective

To determine the safety and efficacy of repeated low doses of LSD in reducing ADHD symptoms compared with placebo.

Design, Setting, and Participants

This was a 6-week, multicenter, double-blind, placebo-controlled, parallel-group phase 2A randomized clinical trial conducted between December 17, 2021, and December 4, 2023. Data were analyzed from March 22, 2024, to August 19, 2024. Outpatient treatment was provided at 2 centers: University Hospital in Basel, Switzerland, and Maastricht University in the Netherlands. Adults aged 18 to 65 years with a prior ADHD diagnosis who presented with moderate to severe symptoms (Adult Investigator Symptom Rating Scale [AISRS] score ≥26 and Clinical Global Impression Severity score ≥4) were eligible for inclusion. Key exclusion criteria included selected current major psychiatric or somatic disorders and the use of potentially interacting medications.

Intervention

Participants received either LSD (20 μg) or placebo twice weekly for 6 weeks (total of 12 doses).

Main Outcome and Measures

The primary outcome was the change in ADHD symptoms from baseline to week 6, assessed by the AISRS and analyzed with a mixed-effects model for repeated measures.

Results

A total of 53 participants were randomized to LSD (n = 27) or placebo (n = 26). Mean (SD) participant age was 37 (12) years, and 22 participants (42%) were female. The LSD group presented a mean AISRS improvement of -7.1 points (95% CI, -10.1 to -4.0). The placebo group presented a mean AISRS improvement of -8.9 points (95% CI, -12.0 to -5.8), with no difference between groups. LSD was physically safe and psychologically well tolerated overall.

Conclusions and Relevance

In this randomized clinical trial, repeated low-dose LSD administration was safe in an outpatient setting, but it was not more efficacious than placebo in reducing ADHD symptoms.

Trial Registration

ClinicalTrials.gov Identifier: NCT05200936.

The role of the psychedelic experience in psilocybin treatment for treatment-resistant depression

OBJECTIVE

To determine the relationships between psilocybin dose, psychedelic experiences, and therapeutic outcome in treatment-resistant depression.

METHODS

For treatment-resistant depression, 233 participants received a single dose of 25, 10, or 1 mg of COMP360 psilocybin (a proprietary, pharmaceutical-grade synthesized psilocybin formulation, developed by the sponsor, Compass Pathfinder Ltd.) with psychological support. The resulting psychedelic experience (Five-Dimensional Altered States of Consciousness questionnaire [5D-ASC] and Emotional Breakthrough Inventory [EBI]) were measured. These proximal variables and outcome 3 weeks post-administration (change in Montgomery-Åsberg Depression Rating Scale [MADRS]) were explored using correlation analysis.

RESULTS

The mean intensity of psychedelic effects was dose-related, but distributions of scores for different doses overlapped considerably. Depression response correlated with select aspects of the psychedelic experience overall and for individual doses. At the 25 mg dose, 5D-ASC dimensions Oceanic Boundlessness (Pearson correlation coefficient r = -0.508) and Visual Restructuralization (r = -0.516), and EBI (r = -0·637) were the variables with the strongest correlation to the Week 3 change from Baseline in MADRS score.

LIMITATIONS

The existence of correlation does not establish causation and exploratory findings require further replication, preferably in larger independent samples.

CONCLUSIONS

The intensity of psychedelic experience overlaps widely across doses and mitigates the risk of unblinding to dose. Correlations between psychedelic experience and outcome suggest specificity in psilocybin's mechanism of action. Quality and intensity of psychedelic experience may be a measure of pharmacodynamic effect and reveal an effective dose response phenomenon for single oral doses.

The Hallucinogen Rating Scale: Updated Factor Structure in a Large, Multistudy Sample

Background

The Hallucinogen Rating Scale (HRS) has been widely used to measure the subjective effects of psychedelics and other psychoactive substances. Its advantages include a basis in phenomenological interviews and clinical studies, straightforward items, and broad coverage of psychedelic effects. Previous studies have attempted to resolve its factor structure but were limited by small samples of participants who took only one substance.

Methods

We obtained 991 HRS questionnaires from the authors of 18 publications involving 13 psychoactive substances. Exploratory factor analysis was used to analyze its factor structure, and mixed-effects analyses of variance were used to compare HRS scores between drugs.

Results

The HRS resolved into 8 factors with good to excellent internal consistency and that intuitively map onto the effects of psychedelics. The factor model also showed good measures of fit that were superior to previous proposed models. Model factors were able to show dose responses for most drugs. Additionally, patterns of responses on the 8 factors significantly differentiated classic psychedelics, such as psilocybin and DMT, from other substance classes, including dissociatives such as ketamine and salvinorin A, empathogens such as MDMA, stimulants such as methylphenidate and amphetamine, and Δ9-tetrahydrocannabinol. The factor of meaningfulness also uniquely differentiated psychedelics from all other substances.

Conclusions

These data show that the HRS is an intuitive and psychometrically sound tool for measuring the effects of psychedelic drugs, and it may also have utility for measuring the effects of other drugs and altered states of consciousness.

Ketamine's Altered States Meta-Analysis: The Relationship Between Psychomimetic and Clinical Effects With Focus in Depression

BACKGROUND

In recent years, there has been a significant focus on exploring the potential therapeutic impact of altered states of consciousness on treatment outcomes for mental illness, with the goal of enhancing therapeutic strategies and patient results.

METHODS

This meta-analysis was designed to investigate the potential link between the psychomimetic effects of ketamine and clinical outcomes in mental health, which adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

Eleven studies were selected for meta-analysis, and the main result did not find a significant correlation between the psychoactive effects of ketamine and clinical outcomes either in mental illness (n = 11; n's = 27; r = 0.06 [-0.05, 0.17]; P = 0.268) or depression exclusively (n = 10; n's = 25; r = 0.03 [-0.07, 0.13]; P = 0.561). High heterogeneity was found for general analysis ( I2 = 80.78). Egger's regression did not indicate publication bias (intercept = 1.57; SE = 1.49, P = 0.30). No significant Kendall's rank correlation coefficient was observed ( τ = 0.02, P = 0.88) indicating funnel plot symmetry. The sub-analyses, aimed at minimizing study variability by specifically examining factors such as patient disorders (limited to depression), methods of administration (exclusively intravenous), types of assessment instruments, and the timing of evaluations, also yielded no significant findings.

CONCLUSION

This meta-analysis suggests that the altered states of consciousness experienced during ketamine sessions are not directly linked to clinical outcomes. However, it is important to acknowledge that the limited number of studies and their heterogeneity render this conclusion preliminary, warranting further investigation over time.

[The shifting territories of mental travel]

How does experience outside the present moment become part of living matter? Mental travel, which is both creative and low-carbon, is an experience that anyone can enjoy without needing to abstract from immediacy and project themselves beyond reality. The possibility of such a virtual journey has long fascinated philosophers and then scientists. What does mental travel actually involve? Which neural circuits are engaged? What are the conditions that take us on a hallucinatory journey, deprive us of it, or enable us to control it? What are the adaptive advantages of this imaginary journey? Is it present in other living beings and in our "intelligent" machines?

Catalyst for change: Psilocybin's antidepressant mechanisms-A systematic review

BACKGROUND

Recent clinical trials suggest promising antidepressant effects of psilocybin, despite methodological challenges. While various studies have investigated distinct mechanisms and proposed theoretical opinions, a comprehensive understanding of psilocybin's neurobiological and psychological antidepressant mechanisms is lacking.

AIMS

Systematically review potential antidepressant neurobiological and psychological mechanisms of psilocybin.

METHODS

Search terms were generated based on existing evidence of psilocybin's effects related to antidepressant mechanisms. Following Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, 15 studies were systematically reviewed, exploring various therapeutic change principles such as brain dynamics, emotion regulation, cognition, self-referential processing, connectedness, and interpersonal functioning.

RESULTS

Within a supportive setting, psilocybin promoted openness, cognitive and neural flexibility, and greater ability and acceptance of emotional experiences. A renewed sense of connectedness to the self, others, and the world emerged as a key experience. Imaging studies consistently found altered brain dynamics, characterized by reduced global and within default mode network connectivity, alongside increased between-network connectivity.

CONCLUSIONS

Together, these changes may create a fertile yet vulnerable window for change, emphasizing the importance of a supportive set, setting, and therapeutic guidance. The results suggest that psilocybin, within a supportive context, may induce antidepressant effects by leveraging the interplay between neurobiological mechanisms and common psychotherapeutic factors. This complements the view of purely pharmacological effects, supporting a multileveled approach that reflects various relevant dimensions of therapeutic change, including neurobiological, psychological, and environmental factors.

Zeifman R, Stewart K, Janssen-Aguilar R, Lou W, Jetly R, Monson CM, Bhat V. Psilocybin-assisted massed cognitive processing therapy for chronic posttraumatic stress disorder: Protocol for an open-label pilot feasibility trial

BACKGROUND

Posttraumatic stress disorder (PTSD) affects 3.9% of the general population. While massed cognitive processing therapy (CPT) has demonstrated efficacy in treating chronic PTSD, a substantial proportion of patients still continue to meet PTSD criteria after treatment, highlighting the need for novel therapeutic approaches. Preliminary evidence supports the potential therapeutic action of psilocybin to alleviate PTSD symptoms. This open-label pilot study aims to evaluate the feasibility, tolerability, and preliminary efficacy of a single dose 25 mg psilocybin in combination with one week of massed CPT in patients with chronic PTSD.

METHOD

Fifteen participants with chronic PTSD will undergo 12 CPT sessions, two psilocybin-related psychotherapy sessions, and one psilocybin dosing session over a 7-days period. The primary outcomes are feasibility and tolerability, which will be measured by recruitment rates, withdrawal, data completion, adherence, number and nature of adverse events. Secondary objectives include assessing the preliminary efficacy of psilocybin-assisted CPT in reducing PTSD severity, self-reported treatment outcomes and exploring putative mechanisms of change. Participants will be monitored weekly for 12 weeks post-treatment and passive data relevant to mental health and well-being will be collected using a wearable device.

DISCUSSION

This trial will generate important preliminary data on the use of psilocybin-assisted CPT for treating PTSD. The findings will guide the design of a multi-site, large-scale randomized control trial to more rigorously assess the efficacy of this intervention. De-identified data from this study will be available upon request after publication of the results. This study represents a promising and innovative approach to PTSD treatment, potentially offering an alternative therapeutic option for individuals unresponsive to conventional therapies.

TRIAL REGISTRATION

ClinicalTrials.gov NCT06386003.

Ayahuasca-assisted meaning reconstruction therapy for grief: a non-randomized clinical trial protocol

Background

Psychotherapy for Prolonged Grief Disorder (PGD), a condition characterized by an intense and persistent grief response, has received increased attention over the past decades. Evidence-based approaches to prevent PGD are currently scarce, and not always effective. This paper introduces a protocol for a clinical trial exploring the effectiveness of a Meaning Reconstruction psychotherapy approach (MR) assisted with ayahuasca, a traditional indigenous medicine.

Method

The outlined protocol is a three-arm, non-randomized controlled trial focused on reducing normal and pathological grief symptoms, comparing the effectiveness of Ayahuasca-assisted MR therapy (A-MR), MR therapy alone (MR) and No Treatment (NT). At least 69 people who lost a first-degree relative during the prior year, and with a Texas Revised Inventory of Grief score up 39 (TRIG ≥ 40), will participate in the trial. Participants will be allocated to an A-MR (n ≥ 23), MR (n ≥ 23) or NT (n ≥ 23) group. Those from the A-MR and MR therapy groups will undergo a therapeutic process involving 9 sessions of online psychotherapy. In addition, the A-MR condition involves 2 group sessions of ayahuasca. The primary outcomes will be normal and pathological grief severity as measured by the TRIG and Traumatic Grief Inventory Self-Report (TGI-SR), administered at baseline, post-treatment, and 3-month follow up. Measures of quality of life, post-traumatic growth, meaning-made, psychological flexibility, and self-belief consistency will be also included. In addition, subjective effects of ayahuasca and acceptance-avoidance promoting effects will be assessed following ayahuasca administration. Finally, we will analyze the potential mediating effect of meaning-made, psychological flexibility and self-belief consistency in grief symptoms (as measured by the TRIG and TGI).

Discussion

This trial is the first to empirically examinate the potential of psychedelic-assisted psychotherapy for grief, as well as the potential processes of change that may account for it.

Clinical trial registration

https://clinicaltrials.gov, identifier NCT06150859.

Multimodal neurophenomenology of advanced concentration absorption meditation: An intensively sampled case study of Jhana

Using a combination of fMRI, EEG, and phenomenology ratings, we examined the neurophenomenology of advanced concentrative absorption meditation, namely jhanas (ACAM-J), in a practitioner with over 23,000 h of meditation practice. Our study shows that ACAM-J states induce reliable changes in conscious experience and that these experiences are related to neural activity. Using resting-state fMRI functional connectivity, we found that ACAM-J is associated with decreased within-network modularity, increased global functional connectivity (GFC), and desegregation of the default mode and visual networks. Compared to control tasks, the ACAM-J were also related to widespread decreases in broadband EEG oscillatory power and increases in Lempel-Ziv complexity (LZ, a measure of brain entropy). Some fMRI findings varied by the control task used, while EEG results remained consistent, emphasizing both shared and unique neural features of ACAM-J. These differences in fMRI and EEG-measured neurophysiological properties correlated with specific changes in phenomenology - and especially with ACAM-J-induced states of bliss - enriching our understanding of these advanced meditative states. Our results show that advanced meditation practices markedly dysregulate high-level brain systems via practices of enhanced attention to sensations, corroborating recent neurocognitive theories of meditation as the deconstruction of the brain's cortical hierarchy. Overall, our results suggest that ACAM-J is associated with the modulation of large-scale brain networks in both fMRI and EEG, with potential implications for understanding the mechanisms of deep concentration practices and their effects on subjective experience.

Benefits and Challenges of Ultra-Fast, Short-Acting Psychedelics in the Treatment of Depression

Unlike classical antidepressants, psychedelics such as psilocybin have been shown to induce a rapid antidepressant response. In the wake of this development, interest has emerged in ultra-fast, short-acting psychedelics such as 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) and N,N-dimethyltryptamine (DMT) with the expectation that these can produce rapid antidepressant effects following an intense but brief psychedelic intervention. The current paper reviews the clinical pharmacology of 5-MeO-DMT and DMT and their potential benefits and challenges in the treatment of depression. Both compounds display affinities for a variety of monoamine receptors and transporters, but mostly so for serotonergic (5HT) receptors, including 5HT1A and 5HT2A. Early clinical trials in small samples have shown that short interventions (15-30 min) with 5-MeO-DMT and DMT are safe and well tolerated and can induce marked improvement in symptoms of depression within 24 hours that sustain for at least 1 week. Data on long-term efficacy are currently scarce but do suggest a prolongation of the treatment response. Potential benefits of these treatments include flexible, single day dosing regimens, achievement of treatment efficacy independent from integrative therapy, and ease of clinical implementation. Future challenges include establishing the duration of the antidepressant effect and strategies on how to sustain the antidepressant response, optimization of treatment delivery parameters, and a mechanistic understanding of the clinical response. Acceptance of ultra-fast, short-acting psychedelics will depend on future randomized, placebo-controlled trials with a focus on replication, duration and maintenance of antidepressant efficacy in large patient samples.

MDMA and MDMA-Assisted Therapy

MDMA (i.e., 3,4-methylenedixoymethamphetamine), commonly known as "Ecstasy" or "Molly," has been used since the 1970s both in recreational and therapeutic settings. The Food and Drug Administration (FDA) designated MDMA-Assisted Therapy (MDMA-AT) as a Breakthrough Therapy for posttraumatic stress disorder (PTSD) in 2017, and the FDA is requiring an additional phase 3 trial after rejecting the initial New Drug Application in 2024. Unlike other psychedelics, MDMA uniquely induces prosocial subjective effects of heightened trust and self-compassion while maintaining ego functioning as well as cognitive and perceptual lucidity. While recreational use in nonmedical settings may still cause harm, especially due to adulterants or when used without proper precautions, conclusions that can be drawn from studies of recreational use are limited by many confounds. This especially limits the extent to which evidence related to recreational use can be extrapolated to therapeutic use. A considerable body of preliminary evidence suggests that MDMA-AT delivered in a controlled clinical setting is a safe and efficacious treatment for PTSD. After a course of MDMA-AT involving three MDMA administrations supported by psychotherapy, 67%-71% of individuals with PTSD no longer meet diagnostic criteria after MDMA-AT versus 32%-48% with placebo-assisted therapy, and effects endure at long-term follow-up. This review primarily aims to distinguish evidence of recreational use in nonclinical settings versus MDMA-AT using pharmaceutical-grade MDMA in controlled clinical settings. This review further describes the putative neurobiological mechanisms of MDMA underlying its therapeutic effects, the clinical evidence of MDMA-AT, considerations at the level of public health and policy, and future research directions.

Phenomenology of Psychedelic Experiences and Psychedelic-Associated Distressing Effects: Quantifying Subjective Experiences

The range of phenomena that can be induced by psychedelic substances is broad and variable, including effects on perception, cognition, and emotion. The umbrella term "psychedelic phenomenology" is used to refer to a combination of altered experiential features, such as hallucinations or ego dissolution, which together constitute a psychedelic experience. However, there is no consensus on the set of alterations of consciousness that qualifies an altered state to be a "psychedelic state." In this chapter we summarize the most commonly discussed changes in subjective experiences which could be seen as "core features" of psychedelic experiences. While acknowledging the rich history of pioneering phenomenological work of the last century, this chapter focuses on more recent developments in the quantitative work on the assessment of these phenomena. We also address the under-researched phenomenology of distressing effects, often referred to as "challenging experiences" or "bad trips," and point to their importance in understanding the therapeutic potential and risks associated with psychedelic phenomenology. Historically, one can find many links between psychedelic phenomenology and the phenomenology of psychopathology. We stress the importance to refine the assessment and description also of distressing effects, to identify factors that promote acute experiences which are beneficial and limit those which can have potentially harmful long-term effects.

Exploring the neurobiological correlates of psilocybin-assisted psychotherapy in eating disorders: a review of potential methodologies and implications for the psychedelic study design

Eating disorders (EDs) are a group of debilitating mental illnesses characterized by maladaptive eating behaviors and severe cognitive-emotional dysfunction, directly affecting 1-3% of the population. Standard treatments are not effective in approximately one third of ED cases, representing the need for scientific advancement. There is emerging evidence for the safety and efficacy of psilocybin-assisted psychotherapy (PAP) to improve treatment outcomes in individuals with EDs. However, the limited knowledge of the neurobiological mechanisms underlying the therapeutic effects of PAP restricts the ability to confirm its clinical utility. This narrative review presents an overview of methodologies used to elucidate the pathophysiological mechanisms of EDs or the effects of psilocybin that could be employed to probe the neurobiological correlates of PAP in EDs, including magnetic resonance imaging and molecular neuroimaging techniques, electrophysiological approaches, and neuroplasticity markers. Finally, the implications of these methodologies are described in relation to the unique features of the psychedelic study design, challenges, limitations, and future directions to advance the field. This paper represents a valuable resource for scientists during study conceptualization and design phases and stimulates advancement in the identification of effective therapeutic interventions for EDs.

Acute dose-dependent effects and self-guided titration of continuous N,N-dimethyltryptamine infusions in a double-blind placebo-controlled study in healthy participants

N,N-dimethyltryptamine (DMT) is a serotonergic psychedelic that is known for its short-lasting effects when administered intravenously. Several studies have investigated the administration of intravenous boluses or combinations of a bolus and a subsequent continuous infusion. However, data on dose-dependent acute effects and pharmacokinetics of continuous DMT infusions are lacking. We used a double-blind, randomized, placebo-controlled, crossover design in 22 healthy participants (11 women, 11 men) who received placebo and DMT (0.6, 1.2, 1.8, and 2.4 mg/min) over an infusion duration of 120 min. We also tested a self-guided titration scheme that allowed participants to adjust the DMT dose rate at prespecified time points to achieve their desired level of subjective effects. Outcome measures included subjective effects, autonomic effects, adverse effects, plasma hormone concentrations, and pharmacokinetics up to 3 h after starting the infusion. DMT infusions exhibited dose-proportional pharmacokinetics and rapidly induced dose-dependent subjective effects that reached a plateau after 30 min. A ceiling effect was observed for "good drug effect" at 1.8 mg/min. The 2.4 mg/min dose of DMT induced greater anxious ego dissolution than the 1.8 mg/min dose and induced significant anxiety compared with placebo. We observed moderate acute tolerance to acute effects of DMT. In the self-guided titration session, the participants opted for moderate to strong psychedelic effects, comparable in intensity to the 1.8 mg/min DMT dose rate in the randomized dosing sessions. These results may assist with dose finding for future DMT research and demonstrate that acute subjective effects of DMT can be rapidly adjusted through dose titration.

Synergistic, multi-level understanding of psychedelics: three systematic reviews and meta-analyses of their pharmacology, neuroimaging and phenomenology

Serotonergic psychedelics induce altered states of consciousness and have shown potential for treating a variety of neuropsychiatric disorders, including depression and addiction. Yet their modes of action are not fully understood. Here, we provide a novel, synergistic understanding of psychedelics arising from systematic reviews and meta-analyses of three hierarchical levels of analysis: (1) subjective experience (phenomenology), (2) neuroimaging and (3) molecular pharmacology. Phenomenologically, medium and high doses of LSD yield significantly higher ratings of visionary restructuralisation than psilocybin on the 5-dimensional Altered States of Consciousness Scale. Our neuroimaging results reveal that, in general, psychedelics significantly strengthen between-network functional connectivity (FC) while significantly diminishing within-network FC. Pharmacologically, LSD induces significantly more inositol phosphate formation at the 5-HT2A receptor than DMT and psilocin, yet there are no significant between-drug differences in the selectivity of psychedelics for the 5-HT2A, 5-HT2C, or D2 receptors, relative to the 5-HT1A receptor. Our meta-analyses link DMT, LSD, and psilocybin to specific neural fingerprints at each level of analysis. The results show a highly non-linear relationship between these fingerprints. Overall, our analysis highlighted the high heterogeneity and risk of bias in the literature. This suggests an urgent need for standardising experimental procedures and analysis techniques, as well as for more research on the emergence between different levels of psychedelic effects.

Acute effects of R-MDMA, S-MDMA, and racemic MDMA in a randomized double-blind cross-over trial in healthy participants

Racemic 3,4-methylenedioxymethamphetamine (MDMA) acutely increases mood, feelings of empathy, trust, and closeness to others and is investigated to assist psychotherapy. Preclinical research indicates that S-MDMA releases monoamines and oxytocin more potently than R-MDMA, whereas R-MDMA more potently stimulates serotonin 5-hydroxytryptamine-2A receptors. S-MDMA may have more stimulant properties, and R-MDMA may be more psychedelic-like. However, acute effects of S- and R-MDMA have not been examined in a controlled human study. We used a double-blind, randomized, placebo-controlled, crossover design to compare acute effects of MDMA (125 mg), S-MDMA (125 mg), R-MDMA (125 mg and 250 mg), and placebo in 24 healthy participants. Outcome measures included subjective, autonomic, and adverse effects, pharmacokinetics, and plasma oxytocin, prolactin, and cortisol concentrations. S-MDMA (125 mg) induced greater subjective effects ("stimulation," "drug high," "happy," "open") and higher increases in blood pressure than R-MDMA (both 125 and 250 mg) and MDMA (125 mg). Unexpectedly, R-MDMA did not produce more psychedelic-like effects than S-MDMA. S-MDMA increased plasma prolactin more than MDMA, and S-MDMA increased plasma cortisol and oxytocin more than MDMA and R-MDMA. The plasma elimination half-life of S-MDMA was 4.1 h after administration. The half-life of R-MDMA was 12 and 14 h after the administration of 125 and 250 mg, respectively. Half-lives for S-MDMA and R-MDMA were 5.1 h and 11 h, respectively, after racemic MDMA administration. Concentrations of the CYP2D6-formed MDMA-metabolite 4-hydroxy-3-methoxymethamphetamine were lower after R-MDMA administration compared with S-MDMA administration. The pharmacokinetic findings are consistent with the R-MDMA-mediated inhibition of CYP2D6. Stronger stimulant-like effects of S-MDMA in the present study may reflect the higher potency of S-MDMA rather than qualitative differences between S-MDMA and R-MDMA. Equivalent acute effects of S-MDMA, MDMA, and R-MDMA can be expected at doses of 100, 125, and 300 mg, respectively, and need to be investigated.Trial registration: ClinicalTrials.gov identifier: NCT05277636.

Learning how to make use of dissociative therapies

Dissociative therapies are being increasingly explored for their psychiatric applications, although questions remain about how they work and how best to use them. In exploring these questions, this review highlights six key areas of clinical relevance: (1) The possible contributions of functional unblinding when interpreting efficacy data; (2) The degree to which the therapeutic effects of dissociative therapies can be distinguished from the transient forms of relief seen with recreational drug use; (3) Understanding the construct of dissociation as it is tasked with describing the function of dissociative drugs; (4) The investigation of subjective drug effects as predictors of therapeutic outcome; (5) Similarities and differences in the effects of dissociative and classic psychedelics; and (6) The anticipated need for judicious prescribing/deprescribing resources as dissociative therapies proliferate.

Considering distinct positive emotions in psychedelic science

In this review, we discuss psychedelics' acute subjective and persisting therapeutic effects, outline the science of positive emotions, and highlight the value in considering distinct positive emotions in psychedelic science. Psychedelics produce a wide variety of acute subjective effects (i.e. the 'trip'), including positive emotions and affective states such as awe and joy. However, despite a rich literature on distinct emotions and their different correlates and sequelae, distinct emotions in psychedelic science remain understudied. Insofar as psychedelics' acute subjective effects may play a role in their downstream therapeutic effects (e.g. decreased depression, anxiety, and substance misuse), considering the role of distinct positive emotions in psychedelic experiences has the potential to yield more precise statements about psychedelic-related subjective processes and outcomes. We propose here that understanding the role of positive emotions within the context of psychedelic experiences could help elucidate the connection between psychedelics' acute subjective effects and therapeutic outcomes.

The impact of antidepressant discontinuation prior to treatment with psilocybin for treatment-resistant depression

It has been suggested that the recent use and discontinuation of antidepressant drugs compromises the action of psilocybin. As evidence is only available from small or uncontrolled samples, this post hoc analysis investigated this using data from the largest, phase II, randomized controlled trial of psilocybin treatment to date. Data from 233 participants with treatment-resistant depression (TRD) who received 25 mg, 10 mg, or 1 mg of investigational drug COMP360 psilocybin (a proprietary, pharmaceutical-grade synthetic psilocybin formulation, developed by the sponsor, Compass Pathfinder Ltd.), administered with psychological support, were compared for groups of participants who either discontinued one or more antidepressant drugs during screening or entered the trial antidepressant drug free. Measures of depression symptom severity change during the antidepressant drug discontinuation period, baseline suicidality, acute subjective psychedelic effects, and the study's primary endpoint (change in depression symptom severity between Baseline and Week 3) are described for both groups. Antidepressant drug discontinuation was not related to worsening of depression severity before Baseline. Suicidality was comparable between groups at Baseline. Psilocybin treatment efficacy and the subjective psychedelic experience did not appear to be compromised by antidepressant drug discontinuation. Thus, it does not limit the feasibility of psilocybin treatment for the future. These findings also support the overall homogeneity of our findings with psilocybin treatment as a monotherapy for TRD. The prior contradictory reports may come to appear misleading.

Esketamine-Induced Dissociation: A Case Report

Esketamine, the isolated S-enantiomer of ketamine, has been a recent breakthrough as a non-monoaminergic treatment for treatment-resistant depression (TRD). This case report explores a rare adverse event in a 41-year-old female with TRD, who, despite experiencing significant depressive improvement with esketamine, encountered a severe dissociative episode accompanied by hallucinogenic-like phenomena. While esketamine's efficacy in TRD is well-documented, this pronounced dissociation should be taken into consideration by researchers and clinicians before prescribing. As esketamine continues to aid TRD treatment, comprehension of its safety profile becomes essential for informed decision-making, ensuring optimized patient care in the vast development of antidepressant therapies.

The conceptual framework for the therapeutic approach used in phase 3 trials of MDMA-assisted therapy for PTSD

Results from multiple recent studies support further evaluation of 3,4-methylenedioxymethamphetamine (MDMA) in conjunction with psychotherapy (i.e., MDMA-Assisted Therapy) in the treatment of post-traumatic stress disorder (PTSD). In two Phase 3 trials, MDMA-Assisted Therapy comprised a short-term, intensive psychotherapy that included three sessions directly facilitated by MDMA (referred to as "experimental sessions"), as well as a number of non-drug psychotherapy sessions. This treatment model aimed to harness the potential of MDMA to facilitate recall and processing of traumatic memories, and to increase learning in a social context, integrating "top-down" and "bottom-up" approaches to trauma-focused care. To date, the conceptual framework for this treatment has not been described in the scientific literature. This omission has contributed to misunderstandings about both the theoretical underpinnings of this modality and the therapeutic approach that emerges from it. This paper delineates the psychotherapeutic concepts, theories, and historical antecedents underlying the inner-directed approach to MDMA-Assisted Therapy for PTSD. Broadly speaking, this therapeutic framework centered the concept of the participant's inner healing intelligence as the primary agent of change, with the therapeutic relationship being the core facilitative condition fostering the participant's self-directed movement toward recovery and growth. Corollaries to this holistic, self-directed, relational, and trauma-informed framework include a non-pathologizing approach to the participant's embodied experience (including the possibility of intense emotional and somatic expression, experiences of multiplicity, suicidal ideation, and multigenerational and transpersonal experiences), as well as the therapists' own psychodynamic, somatic, and transpersonal awareness, empathic attunement, relational skillfulness, and cultural humility. The use of MDMA in conjunction with this psychotherapy platform outperformed the use of placebo with psychotherapy in Phase 2 and 3 trials, as measured by symptom reduction in participants with PTSD. However, within-group comparisons also identified significant symptom reduction in participants who did not receive MDMA, lending empirical support to the psychotherapy model itself. In addition to comparative efficacy trials, future research should investigate which elements of the conceptual framework and therapeutic approach underlie the clinical benefit in individuals with PTSD.

Enhanced visual contrast suppression during peak psilocybin effects: Psychophysical results from a pilot randomized controlled trial

In visual perception, an effect known as surround suppression occurs wherein the apparent contrast of a center stimulus is reduced when it is presented within a higher-contrast surrounding stimulus. Many key aspects of visual perception involve surround suppression, yet the neuromodulatory processes involved remain unclear. Psilocybin is a serotonergic psychedelic compound known for its robust effects on visual perception, particularly texture, color, object, and motion perception. We asked whether surround suppression is altered under peak effects of psilocybin. Using a contrast-matching task with different center-surround stimulus configurations, we measured surround suppression after 25 mg of psilocybin compared with placebo (100 mg niacin). Data on harms were collected, and no serious adverse events were reported. After taking psilocybin, participants (n = 6) reported stronger surround suppression of perceived contrast compared to placebo. Furthermore, we found that the intensity of subjective psychedelic visuals induced by psilocybin correlated positively with the magnitude of surround suppression. We note the potential relevance of our findings for the field of psychiatry, given that studies have demonstrated weakened visual surround suppression in both major depressive disorder and schizophrenia. Our findings are thus relevant to understanding the visual effects of psilocybin, and the potential mechanisms of visual disruption in mental health disorders.

Morphological correlates of anxiety-related experiences during a ketamine infusion

OBJECTIVES

Ketamine exerts rapid antidepressant effects by enhancing neuroplasticity, particularly in the amygdala and hippocampus-regions involved in fear processing and learning. While the role of ketamine's dissociative effects in its antidepressant response is debated, anxiety experienced during infusion has been negatively correlated with treatment outcomes.

METHODS

In this single-blind, placebo-controlled study, a subset of 17 healthy volunteers (6 males, 23.12 ± 1.9 years) received intravenously a placebo in the first and 0.5 mg/kg racemic ketamine in the second session. Anxiety-related experiences were assessed by the 5D-ASC score obtained post-infusion, structural magnetic resonance imaging scans were acquired 4 h post-infusion. An anxiety-score was obtained from the 5D-ASC. Relation between post-placebo amygdala volume, hippocampal volume, and its subfields with the anxiety-score were assessed using linear regression models.

RESULTS

Results showed a statistically significant negative relation between hippocampal head volume and the anxiety score (β = -0.733, p = 0.006), with trending negative association for each subfield's head and the score.

CONCLUSION

These findings suggest that anxiety-related experiences during ketamine infusion may be mediated by the hippocampus, with smaller hippocampal volumes leading to more anxiety-related experiences. Thus, hippocampal subfield volumes may be used as a predictor for anxiety-related events during ketamine use and might predict treatment outcome in future approaches.

Functional activity and connectivity signatures of ketamine and lamotrigine during negative emotional processing: a double-blind randomized controlled fMRI study

Ketamine is a highly effective antidepressant (AD) that targets the glutamatergic system and exerts profound effects on brain circuits during negative emotional processing. Interestingly, the effects of ketamine on brain measures are sensitive to modulation by pretreatment with lamotrigine, which inhibits glutamate release. Examining the antagonistic effects of ketamine and lamotrigine on glutamate transmission holds promise to identify effects of ketamine that are mediated through changes in the glutamatergic system. Investigating this modulation in relation to both the acute and sustained effects of ketamine on functional activity and connectivity during negative emotional processing should therefore provide novel insights. 75 healthy subjects were investigated in a double-blind, single-dose, randomized, placebo-controlled, parallel-group study with three treatment conditions (ketamine, lamotrigine pre-treatment, placebo). Participants completed an emotional face viewing task during ketamine infusion and 24 h later. Acute ketamine administration decreased hippocampal and Default Mode Network (DMN) activity and increased fronto-limbic coupling during negative emotional processing. Furthermore, while lamotrigine abolished the ketamine-induced increase in functional connectivity, it had no acute effect on activity. Sustained (24 h later) effects of ketamine were only found for functional activity, with a significant reduction in the posterior DMN. This effect was blocked by pretreatment with lamotrigine. Our results suggest that both the acute increases in fronto-limbic coupling and the delayed decrease in posterior DMN activity, but not the attenuated limbic and DMN recruitment after ketamine, are mediated by altered glutamatergic transmission.

Snapshot of 5-HT 2A receptor activation in the mouse brain via IP 1 detection

The distinct subjective effects that define psychedelics such as LSD, psilocybin or DOI as drug class are causally linked to activation of the serotonin 2A receptor (5-HT 2A R). However, some aspects of 5-HT 2A R pharmacology remain elusive, such as what molecular drivers differentiate psychedelic from non-psychedelic 5-HT 2A R agonists. We developed an ex vivo platform to obtain snapshots of drug-mediated 5-HT 2A R engagement of the canonical G q/11 pathway in native tissue. This non-radioactive methodology captures the pharmacokinetic and pharmacodynamic events leading up to changes in inositol monophosphate (IP 1 ) in the mouse brain. The specificity of this method was assessed by comparing IP 1 levels in homogenates from the frontal cortex in DOI-treated wild-type and 5-HT 2A R-KO animals compared to other brain regions, namely striatum and cerebellum. Furthermore, we encountered that head-twitch response (HTR) counts and IP 1 in the frontal cortex were correlated. We observed that IP 1 levels in frontal cortex homogenates from mice treated with LSD and lisuride vary in magnitude, consistent with LSD's 5-HT 2A R agonism and psychedelic nature, and lisuride's lack thereof. MDMA evoked an increase of IP 1 signal in the frontal cortex that were not matched by the serotonin precursor 5-HTP or the serotonin reuptake inhibitor fluoxetine. We attribute differences in the readout primarily to the indirect stimulation of 5-HT 2A R by MDMA via serotonin release from its presynaptic terminals. This methodology enables capturing a snapshot of IP 1 turnover in the mouse brain that can provide mechanistic insights in the study of psychedelics and other serotonergic agents pharmacodynamics.

Altered states of consciousness in Danish healthy volunteers and recreational users of psilocybin and the possible impact of setting and intention: Danish validation of the five-dimensional altered states of consciousness questionnaire

BACKGROUND

Psychedelic substances reliably induce marked altered states of consciousness (ASC), which may be important for lasting effects and clinical outcomes of psychedelic intervention. Several instruments are available to measure the acute psychedelic experience, of which the Five Dimensional Altered States of Consciousness Questionnaire (5D-ASC) is commonly used. The questionnaire can be scored and analyzed as having five dimensions or 11 subscales, but the two have not been evaluated with comparable factor analysis methods.

METHODS

The Danish translation of the 5D-ASC was completed by one sample of healthy volunteers receiving psilocybin in a laboratory setting (N = 47) and one sample of recreative users5D-ASC of psychedelics (N = 550), who reported retrospectively through an online survey based on their most recent experience with psilocybin. We calculated internal consistency measures of Cronbach's alpha and McDonald's omega, conducted a confirmatory factor analysis of the previously suggested factor structures, and tested for possible associations between the 5D-ASC total scores and dose, setting, and intention. For the 11 subscales, we reported omega-sem (composite reliability) using the parameters of the fitted confirmatory factor analyses model.

RESULTS

Confirmatory factor analysis showed that the 11 subscales had a good fit to data and showed a better fit compared to the originally proposed five-dimensional solution and good internal consistencies. We further found that the 5D-ASC total scores correlated positively with the dose in the recreative sample. We found no correlations between 5D-ASC total scores and intention or setting.

DISCUSSION

We find the Danish 5D-ASC to be a valid tool for measuring ASC among Danish-speaking individuals.

Autonomic nervous system activity correlates with peak experiences induced by DMT and predicts increases in well-being

BACKGROUND

Non-ordinary states of consciousness induced by psychedelics can be accompanied by so-called "peak experiences," characterized at the emotional level by their intensity and positive valence. These experiences are strong predictors of positive outcomes following psychedelic-assisted therapy, and it is therefore important to better understand their biology. Despite growing evidence that the autonomic nervous system (ANS) plays an important role in mediating emotional experiences, its involvement in the psychedelic experience is poorly understood. The aim of this study was to investigate to what extent changes in the relative influence of the sympathetic (SNS) and parasympathetic nervous systems (PNS) over cardiac activity may reflect the subjective experience induced by the short-acting psychedelic N,N-Dimethyltryptamine (DMT).

METHODS

We derived measures of SNS and PNS activity from the electrocardiograms of 17 participants (11 males, mean age = 33.8 years, SD = 8.3) while they received either DMT or placebo.

RESULTS

Results show that the joint influence of SNS and PNS ("sympathovagal coactivation") over cardiac activity was positively related to participants' ratings of "Spiritual Experience" and "Insightfulness" during the DMT experience, while also being related to improved well-being scores 2 weeks after the session. In addition, we found that the state of balance between the two ANS branches ("sympathovagal balance") before DMT injection predicted scores of "Insightfulness" during the DMT experience, as well as subsequent sympathovagal coactivation.

CONCLUSION

These findings demonstrate the involvement of the ANS in psychedelic-induced peak experiences and may pave the way to the development of biofeedback-based tools to enhance psychedelic therapy.

Acute dose-dependent effects of mescaline in a double-blind placebo-controlled study in healthy subjects

Classic psychedelics have regained interest in research and therapy. Despite the long tradition of the human use of mescaline, modern data on its dose-dependent acute effects and pharmacokinetics are lacking. Additionally, its mechanism of action has not been investigated in humans. We used a randomized, double-blind, placebo-controlled, crossover design in 16 healthy subjects (8 women) who received placebo, mescaline (100, 200, 400, and 800 mg), and 800 mg mescaline together with the serotonin 5-hydroxytryptamine-2A (5-HT2A) receptor antagonist ketanserin (40 mg) to assess subjective effects, autonomic effects, adverse effects, and pharmacokinetics up to 30 h after drug administration. Mescaline at doses >100 mg induced dose-dependent acute subjective effects. Mescaline increased systolic and diastolic blood pressure at doses >100 mg, with no difference between doses of 200-800 mg. Heart rate increased dose-dependently. Pharmacokinetics of mescaline were dose-proportional. Maximal concentrations were reached after approximately 2 h, and the plasma elimination half-life was approximately 3.5 h. The average duration of subjective effects increased from 6.4 to 14 h with increasing doses of 100-800 mg mescaline. Nausea and emesis were frequent adverse effects at the 800 mg dose. Co-administration of ketanserin attenuated and shortened acute effects of 800 mg mescaline to become comparable to the 100 and 200 mg doses. There were no ceiling effects of the subjective response within the investigated dose range, but tolerability was lower at the highest doses. These results may assist with dose finding for future research and suggest that acute effects of mescaline are primarily mediated by 5-HT2A receptors.

Validation of the imperial psychedelic predictor scale

BACKGROUND

Access to psychedelic drugs is liberalizing, yet responses are highly unpredictable. It is therefore imperative that we improve our ability to predict the nature of the acute psychedelic experience to improve safety and optimize potential therapeutic outcomes. This study sought to validate the 'Imperial Psychedelic Predictor Scale' (IPPS), a short, widely applicable, prospective measure intended to be predictive of salient dimensions of the psychedelic experience.

METHODS

Using four independent datasets in which the IPPS was completed prospectively - two online surveys of 'naturalistic' use (N = 741, N = 836) and two controlled administration datasets (N = 30, N = 28) - we conducted factor analysis, regression, and correlation analyses to assess the construct, predictive, and convergent validity of the IPPS.

RESULTS

Our approach produced a 9-item scale with good internal consistency (Cronbach's α = 0.8) containing three factors: set, rapport, and intention. The IPPS was significantly predictive of 'mystical', 'challenging', and 'emotional breakthrough' experiences. In a controlled administration dataset (N = 28), multiple regression found set and rapport explaining 40% of variance in mystical experience, and simple regression found set explained 16% of variance in challenging experience. In another (N = 30), rapport was related to emotional breakthrough explaining 9% of variance.

CONCLUSIONS

Together, these data suggest that the IPPS is predictive of relevant acute features of the psychedelic experience in a broad range of contexts. We hope that this brief 9-item scale will be widely adopted for improved knowledge of psychedelic preparedness in controlled settings and beyond.

Chemical Reactivity Parameters to Analyze Psychedelics: How Do We Explain the Potency of the Drugs?

Psychedelics are psychoactive substances that produce changes in thoughts and feelings and modifications in perceptions of reality. The most potent psychedelic is also the first semisynthetic hallucinogen (lysergic acid diethylamide). Psychedelics have been investigated for decades because of their potential therapeutic effects in the treatment of neuropsychiatric diseases and also because these drugs are useful in controlling addictions to other substances. In this investigation, we analyze 27 psychedelic molecules. These compounds are serotonergic psychedelics; that is, they are serotonin agonists. We analyze the electron transfer properties to better understand the mechanism of action of these substances. We found that the electron acceptance capacity is related to the potency of the drugs: the best electron acceptor is also the most potent drug. We also used global softness as a parameter of reactivity. Molecules with greater global softness are more polarizable and also have greater potency. These results are useful to continue our understanding of the mechanism of action of psychotropic drugs.

Co-administration of midazolam and psilocybin: differential effects on subjective quality versus memory of the psychedelic experience

Aspects of the acute experience induced by the serotonergic psychedelic psilocybin predict symptomatic relief in multiple psychiatric disorders and improved well-being in healthy participants, but whether these therapeutic effects are immediate or are based on memories of the experience is unclear. To examine this, we co-administered psilocybin (25 mg) with the amnestic benzodiazepine midazolam in 8 healthy participants and assayed the subjective quality of, and memory for, the dosing-day experience. We identified a midazolam dose that allowed a conscious psychedelic experience to occur while partially impairing memory for the experience. Furthermore, midazolam dose and memory impairment tended to associate inversely with salience, insight, and well-being induced by psilocybin. These data suggest a role for memory in therapeutically relevant behavioral effects occasioned by psilocybin. Because midazolam blocks memory by blocking cortical neural plasticity, it may also be useful for evaluating the contribution of the pro-neuroplastic properties of psychedelics to their therapeutic activity.

Pharmacological and non-pharmacological predictors of the LSD experience in healthy participants

The pharmacodynamic effects of lysergic acid diethylamide (LSD) are diverse and different in different individuals. Effects of other psychoactive substances have been shown to be critically influenced by non-pharmacological factors such as personality traits and mood states. The aim of this study was to determine pharmacological and psychological predictors of the LSD effects in healthy human subjects. This analysis is based on nine double-blind, placebo-controlled, cross-over studies with a total of 213 healthy subjects receiving between 25-200 µg LSD. The influence of sex, age, dose, body weight, pharmacogenetic, drug experience, personality, setting, and mood before drug intake on the peak autonomic and total subjective responses to LSD was investigated using multiple linear mixed effects models and Least Absolute Shrinkage and Selection Operator regression. Results were adjusted for LSD dose and corrected for multiple testing. LSD dose emerged as the most influential predictor, exhibiting a positive correlation with most response variables. Pre-drug mental states such as "Well-Being", "Emotional Excitability", and "Anxiety" were also important predictor for a range of subjective effects but also heart rate and body temperature. The trait "Openness to Experiences" was positively correlated with elevated ratings in "Oceanic Boundlessness" and mystical-type effects. Previous experiences with hallucinogens have been negatively associated with the overall altered state of consciousness and particularly with "Anxious Ego Dissolution". Acute anxiety negatively correlated with the genetically determined functionality of the Cytochrome 2D6 enzyme. In summary, besides the amount of drug consumed, non-pharmacological factors such as personal traits and current mood also significantly predicted the subjective drug experience. Sex and body weight were not significant factors in influencing the drug experience.

Development of the Japanese version of the Challenging Experience Questionnaire

INTRODUCTION

The therapeutic potential of psychedelics for various mental disorders has gained significant interest. Previous studies have highlighted that psychedelics induce psychoactive effects, including challenging aspects of experiences. These experiences are assessed using the Challenging Experience Questionnaire (CEQ), yet its Japanese version has been unavailable. This study aimed to create a Japanese version of the CEQ.

METHODS

We followed the "Principles of Good Practice for the Translation and Cultural Adaptation Process for Patient-Reported Outcomes (PRO) Measures: Report of the ISPOR Task Force for Translation and Cultural Adaptation." Initially, two Japanese psychiatrists independently conducted the forward translations. These were then reconciled into a single version, which was back-translated into English. The original authors reviewed this back-translation for accuracy, leading to revisions through continuous dialogue until the original authors approved the final version.

RESULTS

The final, approved back-translated version of the CEQ is presented in the figure.

CONCLUSIONS

This study developed a Japanese version of the CEQ, enabling the assessment of challenging experiences during psychedelic-assisted therapy for Japanese speakers. Further studies are needed to assess the reliability and validity of this newly translated version.

Acute psychotropic, autonomic, and endocrine effects of 5,6-methylenedioxy-2-aminoindane (MDAI) compared with 3,4-methylenedioxymethamphetamine (MDMA) in human volunteers: A self-administration study

The acute psychoactive, autonomic, and endocrine effects of the new psychoactive substance (NPS) 5,6-methylenedioxy-2-aminoindane (MDAI; 3.0 mg/kg, range 180-228 mg) were investigated in six healthy volunteers (four males, two females) in a non-blinded fashion without placebo. Subjective, cardiovascular, and endocrine responses were compared with two different doses of 3,4-methylenedioxymethamphetamine (MDMA) (75 mg and 125 mg) described in previously published placebo-controlled studies, which used identical outcome measures including Visual Analogue Scales (VAS), the Adjective Mood Rating Scale (AMRS), and the 5 Dimensions of Altered States of Consciousness (5D-ASC) scale. MDAI was well tolerated and produced subjective effects comparable with those of 125 mg MDMA. MDAI increased blood pressure similar to 125 mg MDMA but did not increase heart rate or body temperature. MDAI increased cortisol and prolactin levels and could be detected in serum about 20 min post ingestion and remained detectable at least for 4 days. In urine, MDAI was detectable over a period of at least 6 days. Further clinical investigations are warranted to assess whether MDAI could serve as drug with medicinal properties.

Within-subject comparison of near-death and psychedelic experiences: acute and enduring effects

Mystical-like states of consciousness may arise through means such as psychedelic substances, but may also occur unexpectedly during near-death experiences (NDEs). So far, research studies comparing experiences induced by serotonergic psychedelics and NDEs, along with their enduring effects, have employed between-subject designs, limiting direct comparisons. We present results from an online survey exploring the phenomenology, attribution of reality, psychological insights, and enduring effects of NDEs and psychedelic experiences (PEs) in individuals who have experienced both at some point during their lifetime. We used frequentist and Bayesian analyses to determine significant differences and overlaps (evidence for null hypotheses) between the two. Thirty-one adults reported having experienced both an NDE (i.e. NDE-C scale total score ≥27/80) and a PE (intake of lysergic acid diethylamide, psilocybin/mushrooms, ayahuasca, N,N-dimethyltryptamine, or mescaline). Results revealed areas of overlap between both experiences for phenomenology, attribution of reality, psychological insights, and enduring effects. A finer-grained analysis of the phenomenology revealed a significant overlap in mystical-like effects, while low-level phenomena (sensory effects) were significantly different, with NDEs displaying higher scores of disembodiment and PEs higher scores of visual imagery. This suggests psychedelics as a useful model for studying mystical-like effects induced by NDEs, while highlighting distinctions in sensory experiences.