Clarifying and measuring the characteristics of experiences that involve a loss of self or a dissolution of its boundaries.

Mystical experience, non-dual awareness, selflessness, self-transcendent experience, and ego-dissolution have become increasingly prominent constructs in meditation and psychedelic research. However, these constructs and their measures tend to be highly overlapping, imprecise, and poorly integrated with similar pathological experiences. The present study seeks to clarify the common factors involved in the characteristics of these experiences using precise distinctions across an array of experience contexts (including meditation, psychedelics, and psychopathology). Participants (N = 386) completed an online survey about an experience that involved either a dissolution of self-boundaries or a loss of selfhood. Confirmatory factor analyses resulted in 16 experience characteristics, including multiple types of changes in sense of self, co-occurring phenomenology, and cognitive and affective responses. Qualitative thematic analysis provided rich descriptions of experience characteristics. Taken together, results lead to a more specific measurement model and descriptive account of experiences involving a loss of self or self-boundary.

Making Sense of Spiritual, Metaphysical, and Eschatological Elements in Delusions: A Qualitative Study Using Interpretative Phenomenological Analysis.

BACKGROUND: Spiritual, metaphysical, or eschatological elements in delusions (SMEDs) are frequent and often subjectively regarded as profound transformational experiences, similar to mystical experiences. This study aimed (1) to explore how SMEDs are experienced and in which aspects they are similar to mystical experiences and (2) to investigate how individuals make sense of SMED. METHODS: Seven participants were interviewed, and their expressions were analyzed using interpretative phenomenological analysis. RESULTS: We found that SMEDs were similar to mystical experiences with regard to alterations in perception of space, time, and unity. Furthermore, SMEDs were accompanied by a sense of enlightenment that however remained ineffable. SMEDs were interpreted from different viewpoints, i.e., as a source of ontological insight, as a mental health issue, as an inspiration for a new orientation in the world, and, for some participants, as an example of the limits of knowledge. Making sense of SMED appeared to follow a lively internal dialogue in which various, sometimes contradictory positions were reflected upon. Participants usually struggled to align the ostensible ontological significance of SMED to the dominating illness explanation. CONCLUSION: SMEDs have similarities to mystical experiences, but integrating SMED into one's own life is challenging. We propose a philosophical, non-pathological interpretation of SMED derived from a novel perspective on mystical experience which may also have some therapeutic utility.

Anton Boisen Reconsidered: Psychiatric Survivor and Mad Prophet.

Anton Boisen was a seminal figure in the psychology of religion and pastoral psychology, but scholars have remained skeptical about his theoretical contributions and have perpetuated the stigma surrounding his psychiatric diagnosis and incarceration. I argue that Boisen was a prophet, ahead of his time, and that the academy has been slow to hear his salient critiques of the psychiatric system, and his contention that "psychosis" and "mystical experience" are overlapping phenomena. Most significantly, scholars have ignored the kernel of prophetic truth in Boisen's own visionary experience, which, remarkably, in 1920, predicted the ecological crisis of our current age. Reclaiming Boisen's unique voice might help us reclaim the uniqueness of the disciplines he helped birth.

The relationship between individual differences in gray matter volume and religiosity and mystical experiences: A preregistered voxel-based morphometry study.

The neural substrates of religious belief and experience are an intriguing though contentious topic. Here, we had the unique opportunity to establish the relation between validated measures of religiosity and gray matter volume in a large sample of participants (N = 211). In this registered report, we conducted a confirmatory voxel-based morphometry analysis to test three central hypotheses regarding the relationship between religiosity and mystical experiences and gray matter volume. The preregisterered hypotheses, analysis plan, preprocessing and analysis code and statistical brain maps are all available from online repositories. By using a region-of-interest analysis, we found no evidence that religiosity is associated with a reduced volume of the orbito-frontal cortex and changes in the structure of the bilateral inferior parietal lobes. Neither did we find support for the notion that mystical experiences are associated with a reduced volume of the hippocampus, the right middle temporal gyrus or with the inferior parietal lobes. A whole-brain analysis furthermore indicated that no structural brain differences were found in association with religiosity and mystical experiences. We believe that the search for the neural correlates of religious beliefs and experiences should therefore shift focus from studying structural brain differences to a functional and multivariate approach.

Long-term follow-up of psilocybin-facilitated smoking cessation.

BACKGROUND: A recent open-label pilot study (N = 15) found that two to three moderate to high doses (20 and 30 mg/70 kg) of the serotonin 2A receptor agonist, psilocybin, in combination with cognitive behavioral therapy (CBT) for smoking cessation, resulted in substantially higher 6-month smoking abstinence rates than are typically observed with other medications or CBT alone. OBJECTIVES: To assess long-term effects of a psilocybin-facilitated smoking cessation program at ≥12 months after psilocybin administration. METHODS: The present report describes biologically verified smoking abstinence outcomes of the previous pilot study at ≥12 months, and related data on subjective effects of psilocybin. RESULTS: All 15 participants completed a 12-month follow-up, and 12 (80%) returned for a long-term (≥16 months) follow-up, with a mean interval of 30 months (range = 16-57 months) between target-quit date (i.e., first psilocybin session) and long-term follow-up. At 12-month follow-up, 10 participants (67%) were confirmed as smoking abstinent. At long-term follow-up, nine participants (60%) were confirmed as smoking abstinent. At 12-month follow-up 13 participants (86.7%) rated their psilocybin experiences among the five most personally meaningful and spiritually significant experiences of their lives. CONCLUSION: These results suggest that in the context of a structured treatment program, psilocybin holds considerable promise in promoting long-term smoking abstinence. The present study adds to recent and historical evidence suggesting high success rates when using classic psychedelics in the treatment of addiction. Further research investigating psilocybin-facilitated treatment of substance use disorders is warranted.

The epistemic innocence of psychedelic states.

One recent development in epistemology, the philosophical study of knowledge, is the notion of 'epistemic innocence' introduced by Bortolotti and colleagues. This concept expresses the idea that certain suboptimal cognitive processes may nonetheless have epistemic (knowledge-related) benefits. The idea that delusion or confabulation may have psychological benefits is familiar enough. What is novel and interesting is the idea that such conditions may also yield significant and otherwise unavailable epistemic benefits. I apply the notion of epistemic innocence to research on the transformative potential of psychedelic drugs. The popular epithet 'hallucinogen' exemplifies a view of these substances as fundamentally epistemically detrimental. I argue that the picture is more complicated and that some psychedelic states can be epistemically innocent. This conclusion is highly relevant to policy debates about psychedelic therapy. Moreover, analysing the case of psychedelics can shed further light on the concept of epistemic innocence itself.

Measuring the subjective: revisiting the psychometric properties of three rating scales that assess the acute effects of hallucinogens.

OBJECTIVE: In the present study we explored the psychometric properties of three widely used questionnaires to assess the subjective effects of hallucinogens: the Hallucinogen Rating Scale (HRS), the Mystical Experience Questionnaire (MEQ), and the Addiction Research Center Inventory (ARCI). METHODS: These three questionnaires were administered to a sample of 158 subjects (100 men) after taking ayahuasca, a hallucinogen whose main active component is N,N-dimethyltryptamine (DMT). A confirmatory factorial study was conducted to check the adjustment of previous data obtained via theoretical proposals. When this was not possible, we used an exploratory factor analysis without restrictions, based on tetrachoric and polychoric matrices and correlations. RESULTS: Our results sparsely match the theoretical proposals of the authors, perhaps because previous studies have not always employed psychometric methods appropriate to the data obtained. However, these data should be considered preliminary, pending larger samples to confirm or reject the proposed structures obtained. CONCLUSIONS: It is crucial that instruments of sufficiently precise measurement are utilized to make sense of the information obtained in the study of the subjective effects of psychedelic drugs. Copyright © 2016 John Wiley & Sons, Ltd.

The psychedelic effects of cannabis: A review of the literature.

Cannabis and classic psychedelics are controlled substances with emerging evidence of efficacy in the treatment of a variety of psychiatric illnesses. Cannabis has largely not been regarded as having psychedelic effects in contemporary literature, despite many examples of historical use along with classic psychedelics to attain altered states of consciousness. Research into the "psychedelic" effects of cannabis, and delta-9-tetrahydrocannabinol (THC) in particular, could prove helpful for assessing potential therapeutic indications and elucidating the mechanism of action of both cannabis and classic psychedelics. This review aggregates and evaluates the literature assessing the capacity of cannabis to yield the perceptual changes, aversiveness, and mystical experiences more typically associated with classic psychedelics such as psilocybin. This review also provides a brief contrast of neuroimaging findings associated with the acute effects of cannabis and psychedelics. The available evidence suggests that high-THC cannabis may be able to elicit psychedelic effects, but that these effects may not have been observed in recent controlled research studies due to the doses, set, and settings commonly used. Research is needed to investigate the effects of high doses of THC in the context utilized in therapeutic studies of psychedelics aimed to occasion psychedelic and/or therapeutic experiences. If cannabis can reliably generate psychedelic experiences under these conditions, high-THC dose cannabis treatments should be explored as potential adjunctive treatments for psychiatric disorders and be considered as an active comparator in clinical trials involving traditional psychedelic medications.

Validation of the Danish Translation of the Revised Mystical Experience Questionnaire (MEQ30) and Possible Impact of Setting, Dose and Intention.

Research suggests positive changes in both well-being and psychiatric symptoms following a psychedelic experience. One explanation may be the ability of psychedelic compounds to occasion mystical-type experiences. The Revised Mystical Experiences Questionnaire (MEQ30) is designed to assess the intensity and quality of such experiences. We examined the validity, reliability, and factor structure of a Danish translation of the MEQ30 in one sample of healthy volunteers receiving psilocybin in a laboratory setting (N = 47) and two samples of recreative users of psychedelics, in which MEQ30 was reported retrospectively through an online survey based on their most recent experience with psilocybin (N = 834) or their most memorable experience with any psychedelic (N = 500). We conducted a confirmatory factor analysis of the previously suggested factor structures, calculated alpha and omega, and tested the associations between MEQ30 total score and setting, intention and dose. We found excellent internal reliability estimates across all samples, and confirmatory factor analysis showed that a four-factor structure, had the best, fair fit to the data. We further found that the MEQ30 total score was correlated with dose and a spiritual/religious intention, but not with setting. The Danish MEQ30 seems to be a valid tool for accessing mystical-type experiences among Danish-speaking individuals.

The revival of the psychedelic experience scale: Revealing its extended-mystical, visual, and distressing experiential spectrum with LSD and psilocybin studies.

BACKGROUND: Research with the Psychedelic Experience Questionnaire/Scale (PES) focuses on questions relating to mystical experience (Mystical Experience Questionnaire (MEQ)). The psychometric potential of the non-MEQ items of the PES remains largely unexplored. AIMS: We investigated whether the PES also yields subscales besides the MEQ30 subscales. METHODS: Data from 239 PES measurements (140 healthy participants) from six studies with moderate to high doses of lysergic acid diethylamide and/or psilocybin were included. New subscales (with items other than MEQ30) were created and validated as follows: (1) theoretical derivation of candidate items; (2) removal of items with rare experiences; (3) exploratory factor analysis; and (4) confirmatory factor analysis. Correlations of subscales within the PES and between the PES and the 5-Dimensional Altered States of Consciousness Scale (5D-ASC) were performed. In addition, a cluster analysis using all items (except rare experiences) was performed. RESULTS: The reliability of the four original factors of the MEQ30 was confirmed and four additional factors for the non-MEQ items were revealed: paradoxicality, connectedness, visual experience, and distressing experience. The first two additional factors were strongly correlated with the MEQ30 mystical subscale. Adding the new subscales to the MEQ30 subscales increased the explained variance with the 5D-ASC. The cluster analysis confirmed our main results and provided additional insights for future psychedelic psychometrics. CONCLUSION: The study yields a new validated 6-factor structure for extended mystical experience (MEQ40: MEQ30 + Paradoxicality + Connectedness) and covers psychedelic experience as a whole more comprehensively than has hitherto been possible within a single questionnaire (PES48). The entire PES (PES100) can also be used for further future psychedelic-psychometric research.

Fire Kasina advanced meditation produces experiences comparable to psychedelic and near-death experiences: A pilot study.

Psychedelic-assisted therapy studies suggest that the induction of "mystical experiences" combined with psycho-therapy is a possible intervention for psychiatric illness. Advanced meditation may induce powerful experiences comparable to psychedelics. We investigated effects of an intensive meditation practice called Fire Kasina. Six individuals completed a retreat, and participated in an interview in which they described their experiences. They also completed the Revised Mystical Experience Questionnaire (MEQ), Hood Mystical Experience Scale (HME), and Cole's Spiritual Transformation Scale. Mean MEQ scores were 85 %, similar to prior observations of high-dose psilocybin and were stronger than moderate-dose psilocybin (t(5) = 4.41, p = 0.007, d = 1.80; W(5) = 21, p = 0.031). Mean HME scores were 93 %, exceeding levels reported for NDEs (mean 74 %) and high-dose psilocybin (mean 77 %). In qualitative analysis, experiences were described as the most intense of the individual's life, while subsequent transformational effects included substantial shifts in worldview.

Naturalistic psychedelic therapy: The role of relaxation and subjective drug effects in antidepressant response.

BACKGROUND: Psychedelic-assisted therapy (PAT) is permitted in Switzerland under its limited medical use program. Data from patients in this program represent a unique opportunity to analyze the real-world practice of PAT. AIMS: This study compared the subjective effects of lysergic acid diethylamide (LSD) and psilocybin between patients undergoing PAT and healthy volunteers. For the patients, it also investigated the relationship between antidepressant effects and six measures of acute drug effects. METHODS: We compared data on acute psychedelic drug effects between 28 PAT patients with data from 28 healthy participants who participated in a randomized, double-blind crossover trial. All participants received varying doses of psilocybin and LSD. Subjective effects were assessed on an hourly basis during the acute drug effects, and the Mystical Experience Questionnaire (MEQ) was completed retrospectively. For patients, depressive symptoms were assessed using the Montgomery-Åsberg Depression Rating Scale (MADRS). RESULTS: Ratings of overall drug effect and mystical experience were similar across groups. Compared with healthy controls, patients reported lower ratings of ego dissolution. Patients showed a significant decrease in MADRS scores, and the greatest predictor of antidepressant outcome was relaxation during the PAT session. We did not observe a relationship between mystical-type experiences and antidepressant effects. Most patients experienced mild adverse effects which resolved within 48 h. CONCLUSION: PAT reduced depressive symptoms in this heterogeneous patient group. Patients may experience more challenging psychedelic effects and reduced ego dissolution. Hourly assessment of drug effects may predict clinical outcomes better than retrospectively assessed mystical experiences, and the impact of relaxation during PAT should be investigated further.

Meditating on psychedelics. A randomized placebo-controlled study of DMT and harmine in a mindfulness retreat.

BACKGROUND: In recent years, both meditation and psychedelics have attracted rapidly increasing scientific interest. While the current state of evidence suggests the promising potential of psychedelics, such as psilocybin, to enhance meditative training, it remains equivocal whether these effects are specifically bound to psilocybin or if other classical psychedelics might show synergistic effects with meditation practice. One particularly promising candidate is N,N-dimethyltryptamine (DMT), an active ingredient of ayahuasca. AIM: This study aims to investigate the effect of the psychedelic substance DMT, combined with the monoamine oxidase inhibitor harmine (DMT-harmine), on meditative states, compared to meditation with a placebo. METHOD: Forty experienced meditators (18 females and 22 males) participated in a double-blind, placebo-controlled study over a 3-day meditation retreat, receiving either placebo or DMT-harmine. Participants' levels of mindfulness, compassion, insight, and transcendence were assessed before, during, and after the meditation group retreat, using psychometric questionnaires. RESULTS: Compared to meditation with a placebo, meditators who received DMT and harmine self-attributed greater levels of mystical-type experiences, non-dual awareness, and emotional breakthrough during the acute substance effects and, when corrected for baseline differences, greater psychological insight 1 day later. Mindfulness and compassion were not significantly different in the DMT-harmine group compared to placebo. At 1-month follow-up, the meditators who received DMT and harmine rated their experience as significantly more personally meaningful, spiritually significant, and well-being-enhancing than the meditators who received placebo. CONCLUSION: Investigating the impact of DMT-harmine on meditators in a naturalistic mindfulness group retreat, this placebo-controlled study highlights the specific effects of psychedelics during meditation. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT05780216.

Naturalism and the hard problem of mysticism in psychedelic science.

Psychedelic substances are known to facilitate mystical-type experiences which can include metaphysical beliefs about the fundamental nature of reality. Such insights have been criticized as being incompatible with naturalism and therefore false. This leads to two problems. The easy problem is to elaborate on what is meant by the "fundamental nature of reality," and whether mystical-type conceptions of it are compatible with naturalism. The hard problem is to show how mystical-type insights, which from the naturalistic perspective are brain processes, could afford insight into the nature of reality beyond the brain. I argue that naturalism is less restrictive than commonly assumed, allowing that reality can be more than what science can convey. I propose that what the mystic refers to as the ultimate nature of reality can be considered as its representation- and observation-independent nature, and that mystical-type conceptions of it can be compatible with science. However, showing why the claims of the mystic would be true requires answering the hard problem. I argue that we can in fact directly know the fundamental nature of one specific part of reality, namely our own consciousness. Psychedelics may amplify our awareness of what consciousness is in itself, beyond our conceptual models about it. Moreover, psychedelics may aid us to become aware of the limits of our models of reality. However, it is far from clear how mystical-type experience could afford access to the fundamental nature of reality at large, beyond one's individual consciousness. I conclude that mystical-type conceptions about reality may be compatible with naturalism, but not verifiable.

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.

The Effects of Ayahuasca on Psychological Disorders: A Systematic Literature Review.

Ayahuasca is an original Amazonian brew made from the vines and leaves of Psychotroa viridis and Banisteriopsis caapi. Both P. viridis and B. caapi give this brew its unique psychedelic properties which have been revered over centuries. In recent years, ayahuasca has gained attention as a potential therapeutic tool for mental health disorders, including substance abuse and depression. The uniqueness of ayahuasca's therapeutic potential is that it is an amalgamation of its biochemical makeup and the ritual guided by a shaman, along with the interpretation of the participant of their experience. The boom of "ayahuasca tourism" has brought forth testimonies of feeling "cured" of depression, and substance abuse and an improvement in overall well-being. This systematic literature review focuses on summarizing the recently available research on the effectiveness of ayahuasca as a treatment for depression, anxiety, substance abuse, eating disorders, and post-traumatic stress disorder. It also focuses on understanding the effects it has on personality traits that play a significant role in the manifestation of the above-listed mental health conditions effects. Additionally, the review investigates the importance and role the ritual itself plays, often described as the "mystical experience". This systematic literature review aims to explore the current state of knowledge regarding the use of ayahuasca for numerous mental health conditions by analyzing medical research papers published no earlier than September 2017 to no later than May 2023 from Google Scholar and PubMed. A total of 43 articles met the criteria and were used for detailed analysis. This review will synthesize the findings of the studies, examining the potential therapeutic effects of ayahuasca on multiple mental health disorders, the significance of the "mystical experience," and the mechanisms of action underlying its effects. Through the review, ayahuasca proves to be a worthwhile therapeutic tool that if used in the right setting influences mind, body, and spirit. It is important to note that most studies used in this article relied on surveys and self-reporting proving to be a limitation as no clear standard has been achieved to test the efficacy of ayahuasca. The respect for the culture and origin needs to be retained as Western medicine dwells deeper into ayahuasca's benefits.

Psychedelic-induced mystical experiences: An interdisciplinary discussion and critique.

Contemporary research on serotonergic psychedelic compounds has been rife with references to so-called 'mystical' subjective effects. Several psychometric assessments have been used to assess such effects, and clinical studies have found quantitative associations between 'mystical experiences' and positive mental health outcomes. The nascent study of psychedelic-induced mystical experiences, however, has only minimally intersected with relevant contemporary scholarship from disciplines within the social sciences and humanities, such as religious studies and anthropology. Viewed from the perspective of these disciplines-which feature rich historical and cultural literatures on mysticism, religion, and related topics-'mysticism' as used in psychedelic research is fraught with limitations and intrinsic biases that are seldom acknowledged. Most notably, existing operationalizations of mystical experiences in psychedelic science fail to historicize the concept and therefore fail to acknowledge its perennialist and specifically Christian bias. Here, we trace the historical genesis of the mystical in psychedelic research in order to illuminate such biases, and also offer suggestions toward more nuanced and culturally-sensitive operationalizations of this phenomenon. In addition, we argue for the value of, and outline, complementary 'non-mystical' approaches to understanding putative mystical-type phenomena that may help facilitate empirical investigation and create linkages to existing neuro-psychological constructs. It is our hope that the present paper helps build interdisciplinary bridges that motivate fruitful paths toward stronger theoretical and empirical approaches in the study of psychedelic-induced mystical experiences.

A Psychometric Evaluation of the Dutch Revised Mystical Experience Questionnaire.

In the Netherlands, scientific interest in psychedelics and their subjective effects has been increasing. The present study examined the reliability, construct and predictive validity of the Dutch 30-item Revised Mystical Experience Questionnaire (MEQ30), a self-report measure that has been used to assess subjective and mystical experiences occasioned by psychedelics. In an online survey, 322 Dutch-speaking adults retrospectively reported on profound experiences with psychedelics. Confirmatory factor analyses demonstrated that both a four-factor structure and the same model extended with the MEQ30-total score as a second-order latent variable fit the data. Factor scores showed good internal reliability (α = between .81 and .94) and were significantly higher in participants that beforehand endorsed having had a mystical experience compared to those that did not, providing evidence for the construct validity of the questionnaire as a measure for self-reported mystical experiences. Additionally, MEQ30 scores significantly predicted the meaningfulness and spiritual significance of the psychedelic experience, as well as self-reported positive changes in well-being, life satisfaction and behavior, providing preliminary evidence for the predictive validity of the Dutch MEQ30. Findings suggest the reliability and validity of the Dutch MEQ30 and support the use of the scale in future studies on the subjective effects of psychedelics.

Predicting the Intensity of Psychedelic-Induced Mystical and Challenging Experience in a Healthy Population: An Exploratory Post-Hoc Analysis.

Introduction: In psychedelic therapy, mystical as well as challenging experience may influence therapeutic outcome. However, predictors of such experience have not been sufficiently established. Determining predictors of their intensity is, therefore, potentially beneficial in targeting psilocybin therapy for depression. Methods: In a post hoc data analysis of a Phase 1, randomised, double-blind, placebo-controlled, between-groups clinical trial, dosage, personality traits, affect, and individual data were analysed as possible clinical predictors. Eighty-nine healthy volunteers were randomised to receive a single dose of placebo, 10 mg of psilocybin, or 25 mg of psilocybin. ANOVA was used to analyse the relationship between dosage and mystical and/or challenging experience, and correlation analysis for all other variables. Results: The intensity of both mystical and challenging experience was strongly associated with higher dosage. Age was negatively correlated with intensity of challenging experience. Correlation between identified personality traits and either mystical or challenging experience was minimal, with the exception of positive correlation between neuroticism and challenging experience at higher dose. Neither positive nor negative affect indicated correlation with the intensity of either type of experience. Discussion: A limitation of this study is its post hoc, exploratory design; recommendations for further research are provided.

Naturalistic psilocybin use is associated with persisting improvements in mental health and wellbeing: results from a prospective, longitudinal survey.

Introduction: The classic psychedelic psilocybin, found in some mushroom species, has received renewed interest in clinical research, showing potential mental health benefits in preliminary trials. Naturalistic use of psilocybin outside of research settings has increased in recent years, though data on the public health impact of such use remain limited. Methods: This prospective, longitudinal study comprised six sequential automated web-based surveys that collected data from adults planning to take psilocybin outside clinical research: at time of consent, 2 weeks before, the day before, 1-3 days after, 2-4 weeks after, and 2-3 months after psilocybin use. Results: A sample of 2,833 respondents completed all baseline assessments approximately 2 weeks before psilocybin use, 1,182 completed the 2-4 week post-use survey, and 657 completed the final follow-up survey 2-3 months after psilocybin use. Participants were primarily college-educated White men residing in the United States with a prior history of psychedelic use; mean age = 40 years. Participants primarily used dried psilocybin mushrooms (mean dose = 3.1 grams) for "self-exploration" purposes. Prospective longitudinal data collected before and after a planned psilocybin experience on average showed persisting reductions in anxiety, depression, and alcohol misuse, increased cognitive flexibility, emotion regulation, spiritual wellbeing, and extraversion, and reduced neuroticism and burnout after psilocybin use. However, a minority of participants (11% at 2-4 weeks and 7% at 2-3 months) reported persisting negative effects after psilocybin use (e.g., mood fluctuations, depressive symptoms). Discussion: Results from this study, the largest prospective survey of naturalistic psilocybin use to date, support the potential for psilocybin to produce lasting improvements in mental health symptoms and general wellbeing.