Common wisdom in the psychedelic literature suggests that early controlled trials of psychedelic therapy were methodologically flawed. In this review we challenge this view and discuss 11 controlled studies that were conducted in the United States and Canada between 1965 and 1977 to evaluate psychedelic (peak) therapy for individuals suffering from alcohol and opioid use disorder and...
This project investigates how the context of a live concert — including prior expectations, personality, and acute psychoactive substance use — shapes intense emotional and altered-state responses to music, specifically feelings of awe and wonder, mystical-type experiences, and aesthetic chills. The study is part of an ongoing programme of research at the Leiden University PRSM Lab into peak...
The research, understanding, and implementation of psychedelic therapies is characterised by a layered complexity that arises from the dynamic interactions between pharmacological and extra-pharmacological factors, and the embeddedness of psychedelics within broader societal, legal, and regulatory systems ill-equipped to accommodate them. This complexity is compounded by an epistemic...
Scholars of religion have had a long-standing interest in the study of mystical experiences (Schmidt, 2003), dating back to the work of William James (James, 1902). James listed ineffability, noeti...
Psychedelic research has shown that the effects of serotonergic substances, such as psilocybin and LSD, are strongly influenced by the interaction of substance, set, and setting. Mystical-type experiences, often induced by psychedelics, are not solely driven by pharmacological mechanisms but emerge from a dynamic interplay between the psychological state (set), external environment (setting),...
In addition to evidence supporting the use of psychedelics in treating alcohol and tobacco misuse, emerging research suggests that psychedelic experiences may also facilitate beneficial changes in other health behaviors, such as diet, exercise, and meditation. This retrospective, survey-based study explored perceived health behavior changes following psychedelic experiences, from the...
We investigate how the dose of psilocybin truffles and participant characteristics (trait absorption and expectations) influence subjective experiences and neurophysiological outcomes in a naturalistic field setting.The aim is to replicate observed effects of psilocybin from lab-based and clinical studies in a field / naturalistic setting.
BackgroundTaking very small doses of psychedelics (LSD, truffles) over an extended period became prevalent in Western societies for its alleged cognitive benefit, including enhanced creativity. However, in the absence of robust, double-blind-controlled quantitative studies, such claims remain anecdotal.MethodsHere we present results from 3 double-blind placebo-controlled longitudinal trials...
Return to the Real describes how culturally prevalent narratives shape psychedelic experience. Building on Ten Berge’s two-part analysis, our commentary argues that psychedelic effects are best understood within cultural feedback loops linking cultural set and setting, individual expectations, experience, and its articulation back into culture. On this view, psychedelics operate primarily as...
Psychedelic-assisted psychotherapy (PAP) constitutes a novel treatment paradigm in mental health care practice that is currently being evaluated for its clinical efficacy and safety. Insight into the attitudes of clinicians toward PAP remains crucial for its successful integration into mental health care. This cross-sectional survey explores the attitudes of Dutch mental health care...
Objective: This article outlines recommendations from 30 psychedelic researchers on how to create a better psychedelic safety net. Methods: A survey of 30 psychedelic researchers asked them to identify key critical research gaps around psychedelic harm and safety. Results: The critical research gaps identified by the authors included defining the main types of psychedelic harm, the predictors...
Abstract Progress in the scientific study of altered states of consciousness (ASCs) has been hindered by methodological and conceptual problems. At a methodological level there is a lack of agreement on the scales and instruments used to measure and categorize ASCs. At a conceptual level, existing typologies (such as trigger-based, phenomenology-based, attribution-based, neurobiological, and...
The phenomenon of "hearing voices" can be found not only in psychotic disorders, but also in the general population, with individuals across cultures reporting auditory perceptions of supernatural beings. In our preregistered study, we investigated a possible mechanism of such experiences, grounded in the predictive processing model of agency detection. We predicted that in a signal detection...
Rationale: Psychedelic research re-emerged from a period of suppression into the so-called psychedelic renaissance. In parallel, most media reporting has shifted from the overstatement of the risks of psychedelics to overly positive hype. As the empirical evidence is more equivocal than frequently portrayed, the conclusions about the effectiveness of psychedelics should be considered...
ADVERTISEMENT RETURN TO ARTICLES ASAPPREVViewpointNEXTExpectancy Effects Cannot Be Neglected in MDMA-Assisted Therapy ResearchL. Jacob FlamelingL. Jacob FlamelingInstitute of Psychology, Leiden University, Leiden 2333 AK, The NetherlandsMore by L. Jacob Flamelinghttps://orcid.org/0000-0002-1425-1180, Jacob S. AdayJacob S. AdayDepartment of Anesthesiology, University of Michigan, Ann Arbor,...
Research in the last decade has expressed considerable optimism about the clinical potential of psychedelics for the treatment of mental disorders. This optimism is reflected in a considerable increase in research papers, investments by pharmaceutical companies, patents, media coverage, as well as political and legislative changes. However, psychedelic science is facing serious challenges that...
Interest in experiences that can broadly be considered religious, spiritual, mystical, and self-transcendent is growing – largely due to recent advances in psychedelic research (Yaden et al., 2021)...
Research in the last decade has expressed considerable optimism about the clinical potential of psychedelics for the treatment of mental disorders. This optimism is reflected in an increase in research papers, investments by pharmaceutical companies, patents, media coverage, as well as political and legislative changes. However, psychedelic science is facing serious challenges that threaten the...
This paper provides a critical review of several possible mechanisms at different levels of analysis underlying the effects and therapeutic potential of psychedelics. At the (1) biochemical level, psychedelics primarily affect the 5-HT2A receptor, increase neuroplasticity, offer a critical period for social reward learning, and have anti-inflammatory properties. At the (2) neural level,...
Ayahuasca is a plant decoction in traditional Amazonian medicine. Its ritual use has been internationalized, leading to policy challenges that countries should address. This study evaluates the impact of regular ayahuasca ceremony participation on health by assessing the health status of 377 participants in ayahuasca ceremonies in the Netherlands using validated health indicators. A...
Background: Microdoses of psychedelics (i.e. a sub-hallucinogenic dose taken every third day) can reduce symptoms of depression, anxiety and stress according to anecdotal reports and observational studies. Research with medium to high doses of psilocybin points towards potential underlying mechanisms, including the modulation of emotion and interoceptive processing. Aims: In this preregistered...
In response to a recent call to rid psychedelic science of the concept of mystical experience, we argue that acknowledging the varieties and weirdness of psychedelic experiences should be at the heart of any research program on this topic. We highlight the rich tradition and scientific tools for studying mystical-type experiences, their relevance for understanding the therapeutic effects of...
Introduction: Microdosing refers to the repetitive administration of tiny doses of psychedelics (LSD, Psilocybin) over an extended period of time. This practice has been linked to alleged cognitive benefits, such as improved mood and creativity, potentiated by targeting serotonergic 5-HT2A receptors and facilitating cognitive flexibility. Nonetheless, in the absence of robust, quantitative and...
Objective: Recent clinical trials have demonstrated that psilocybin may have strong antidepressant effects, and may be effective in the treatment of depressive disorders when embedded in a psychotherapeutic protocol (psilocybin-assisted psychotherapy; PAP). However, despite promising results, the mechanism(s) that may be responsible for the antidepressant effects of PAP remain contested. Within...
Abstract There is an increased societal trend to engage in microdosing, in which small sub-hallucinogenic amounts of psychedelics are consumed on a regular basis. Following subjective reports that microdosing enhances the experience of nature and art, in the present study we set out to study the effects of psilocybin microdosing on feelings of awe and art perception. In this preregistered...