Neuropharmacology
June 5, 2018
Matthew W. Johnson, Roland R. Griffiths, Peter S. Hendricks et al.
348 citations
Psilocybin, like other classic psychedelics that activate 5-HT2A receptors, has limited reinforcing effects and only marginal, transient non-human self-administration, indicating low abuse potential. Illicit use of psilocybin-containing mushrooms is occasional, with a few lifetime uses being typical. Potential harms include dangerous behavior in unprepared, unsupervised users and exacerbation of mental illness in those predisposed to psychotic disorders, but the scope of use and associated harms are low compared to prototypical abused drugs. The medical model mitigates these risks through dose control, patient screening, preparation, follow-up, and session supervision. If approved as a medicine, the review suggests that Schedule IV placement under the US Controlled Substances Act may be appropriate.
International Review of Psychiatry
July 4, 2018
Peter S. Hendricks
181 citations
A psychological model proposes that the mystical experience induced by classic psychedelics in therapy is characterized by profound awe—a response to a vast stimulus that forces mental structures to accommodate. Awe promotes a 'small self,' which at its extreme resembles ego dissolution or unitive experience. This small self is central to understanding the therapeutic effects that follow. Based on this framework, clinical recommendations are offered to advance psychedelic-assisted psychotherapy.
Journal of Psychopharmacology
October 17, 2017
Peter S. Hendricks, Michael Crawford, Karen L. Cropsey et al.
91 citations
Lifetime use of classic psychedelics, including psilocybin, is associated with lower odds of recent larceny/theft, assault, and arrests for property or violent crimes among over 480,000 U.S. adults surveyed from 2002 to 2014. In contrast, illicit use of other drugs generally increased the odds of these criminal behaviors. Lifetime classic psychedelic use was linked to higher odds of drug distribution, similar to other substances. The findings suggest a potential protective effect of psilocybin against antisocial criminal behavior and support further clinical research in forensic settings.
Journal of Psychopharmacology
January 1, 2014
Peter S. Hendricks, Christopher Clark, Matthew W. Johnson et al.
88 citations
Hallucinogen use among individuals under community corrections supervision with a history of substance involvement was associated with a reduced likelihood of supervision failure, such as noncompliance with legal requirements including alcohol and other drug use. In a longitudinal study of 25,622 people, those who used hallucinogens had 40% lower odds of supervision failure after controlling for confounding factors. The findings suggest hallucinogens may promote abstinence and prosocial behavior in a population with high rates of recidivism.
Journal of Psychopharmacology
March 9, 2021
Otto Simonsson, James Sexton, Peter S. Hendricks
75 citations
People who have used a classic psychedelic at least once in their lifetime report better overall health and are less likely to be overweight or obese, based on data from over 171,000 U.S. adults. The study also found a trend toward lower odds of having a heart condition or cancer in the past year among those who had used a classic psychedelic. The findings suggest that classic psychedelics may be linked to better physical health, but the authors note that further research is needed to determine whether the relationship is causal and to explore possible mechanisms.
International Journal of Drug Policy
May 8, 2019
Megan Webb, Heith Copes, Peter S. Hendricks
75 citations
People who microdose classic psychedelics such as LSD and psilocybin describe themselves as conventional citizens who use the drugs for rational, practical reasons. Through interviews with 30 microdosers, the study found that participants emphasized the rationality of their practice by discussing practical procurement and administration, a connection to general health and wellness awareness, and the benefits of microdosing. They framed their microdosing as embracing traditional middle-class values, which created social distance between themselves and recreational drug users. Unlike recreational users who distance themselves from stigmatized groups, microdosers instead emphasize their connection to conventional citizens, which helps normalize their drug use and supports persistence.
Journal of Psychopharmacology
April 19, 2016
Zach Walsh, Peter S. Hendricks, Stephanie D. Smith et al.
63 citations
Hallucinogen use among inmates at a US county jail was associated with a reduced likelihood of arrest for intimate partner violence (IPV). In a prospective study of 302 inmates, those who used hallucinogens were about 40% less likely to be arrested for IPV, both before and after accounting for other factors. The findings add to evidence that hallucinogens may help reduce problematic behaviors linked to externalizing psychopathology, such as substance misuse and criminality.
Psychedelic Med (New Rochelle)
September 13, 2023
Jacob S. Aday, Brian S. Barnett, Dan Grossman et al.
56 citations
The psychedelic industry has grown into a multibillion dollar sector, with hundreds of companies formed in recent years to commercialize psychedelic-assisted therapies. Investment surged in the late 2010s and early 2020s, focusing on drug discovery, novel formulations, manufacturing, treatment centers, consumer goods, and adjunct technologies. Key challenges include regulatory barriers, high treatment costs, and intellectual property issues. Ethical concerns involve potential adverse effects, cost-cutting, ensuring access for marginalized communities, and reciprocity with Indigenous peoples. Lessons from the ketamine and cannabis industries offer guidance on regulatory approval, clinical implementation, and insurance reimbursement.
Scientific Reports
July 13, 2021
Otto Simonsson, Walter Osika, Robin Carhart‐Harris et al.
54 citations
Lifetime use of classic psychedelics is associated with lower odds of heart disease and diabetes. Analyzing data from the National Survey on Drug Use and Health (2005–2014), people who had ever tried a classic psychedelic had 23% lower odds of past-year heart disease and 12% lower odds of past-year diabetes. The associations persisted after adjusting for other factors. The authors suggest classic psychedelic use might benefit cardiometabolic health but call for more research on causal pathways.
Journal of Psychoactive Drugs
October 8, 2016
Noah W Sweat, Larry W. Bates, Peter S. Hendricks
48 citations
People who have used classic psychedelics and also had a mystical experience solved a creative problem-solving task faster than those who had not, with a large effect. However, the amount of lifetime mystical experience did not predict task performance, indicating that mystical experience does not explain the link between psychedelic use and creativity. The findings suggest that classic psychedelics may enhance creativity through mechanisms separate from those that produce mystical experiences, and that inducing mystical experiences may not be necessary for creativity-boosting interventions.
Frontiers in Psychiatry
February 11, 2020
James D. Sexton, Charles D. Nichols, Peter S. Hendricks
45 citations
Lifetime use of classic tryptamine psychedelics is linked to lower odds of past-month psychological distress and past-year suicidal thinking, while lifetime use of novel phenethylamines is linked to higher odds of past-year suicidal thinking and planning. These findings, from a large nationally representative U.S. survey, suggest that classic tryptamines may hold greater therapeutic potential than novel phenethylamines, which may pose risks for harm. No significant associations were found for other psychedelic classes.
Journal of Affective Disorders
January 26, 2024
Ludwig Honk, Cecilia U.D. Stenfors, Simon B. Goldberg et al.
41 citations
Using data from nearly 10,000 adults in the US and UK, psychedelic use over a two-month period was not linked to changes in psychotic symptoms overall. However, among people with a personal or family history of bipolar disorder, psychedelic use was associated with an increase in symptoms. Conversely, those with a personal history of psychotic disorders experienced a decrease in symptoms. These findings suggest that the effects of psychedelics on psychotic symptoms depend on an individual's psychiatric history.
Psychedelic Med (New Rochelle)
March 13, 2023
David E. Nichols, Charles D. Nichols, Peter S. Hendricks
39 citations
A proposed consensus statement defines psychedelic drugs as substances that reliably produce profound alterations in consciousness, perception, and mood through agonist activity at the serotonin 2A receptor. The definition emphasizes pharmacological mechanism over subjective effects, distinguishing psychedelics from other psychoactive compounds. The authors argue that a standardized definition is essential for advancing medical research, drug development, and clinical applications by providing a clear framework for classification and nomenclature. This consensus aims to reduce ambiguity in scientific and therapeutic contexts, supporting more precise communication and regulatory clarity in psychedelic research.
Hypertension
March 8, 2021
Otto Simonsson, Peter S. Hendricks, Robin Carhart‐Harris et al.
36 citations
Adults who had used a classic psychedelic at least once in their lifetime had 14% lower odds of hypertension in the past year, after adjusting for confounders. The association was strongest for tryptamine psychedelics (DMT, ayahuasca, psilocybin), which were linked to 20% lower odds of hypertension. No significant association was found for LSD or mescaline. The authors note these findings are correlational and call for randomized controlled trials to test causal effects.
Am J Psychiatry
January 1, 2024
Kelley C. O’donnell, Brian T. Anderson, Frederick S. Barrett et al.
31 citations
This critical response addresses misinterpretations and omissions in a commentary by Goodwin and colleagues on psilocybin-assisted therapy, arguing that the commentary misrepresents existing evidence and overlooks key methodological issues. The authors contend that the commentary fails to adequately discuss safety concerns, including adverse events and the potential for psychological distress, and omits important data on long-term outcomes. They emphasize the need for rigorous, balanced evaluation of psilocybin-assisted therapy's risks and benefits, cautioning against overstating positive outcomes while underreporting negative findings. The response calls for more transparent reporting and careful interpretation of clinical trial results.
Neuropharmacology
May 13, 2022
Cynthia E. Ortiz, Haley Maria Dourron, Noah W Sweat et al.
26 citations
Psilocybin-facilitated psychotherapy may be effective across many mental health conditions, but vulnerable populations, who carry a disproportionate mental health burden, have been largely excluded from clinical research. This report highlights the need to include these groups in studies, considering their problematic historical context and differential experiences with psychedelics. It offers actionable recommendations for future research, such as improved recruitment strategies, careful communication of subjective effects, building therapeutic alliance, multicultural competence, and flexible study designs. The authors call for expanded and improved research in this rapidly advancing field.
Journal of Psychopharmacology
March 1, 2022
Neiloufar Family, Peter S. Hendricks, Luke T. J. Williams et al.
23 citations
LSD doses of 50, 75, and 100 micrograms are tolerable and safe in healthy adults when administered in a novel group-based intervention paradigm with one attendant per participant. Thirty-two adults (mean age 28.8 years) received LSD or placebo across open-label and double-blind designs. No serious adverse events occurred; 28% of participants reported at least one mild expected adverse event and one moderate event. Peak blood plasma levels appeared 1.2 to 2 hours after administration, with an apparent half-life of 2.8 to 4.3 hours. LSD produced greater subjective effects than placebo, including mystical-type experiences. Further research is needed in clinical populations.
Psychiatr Res Clin Pract
February 11, 2025
Jules Evans, Marc Aixalà, Brian T. Anderson et al.
18 citations
Thirty psychedelic researchers identified critical gaps in knowledge about harms from psychedelic use, including how to define those harms, predict them, and treat them effectively. They recommend better online information, peer support groups, affordable therapy, and psychiatric consultation for people experiencing post-psychedelic difficulties. The researchers also call for improved funding for a psychedelic safety net, suggesting that psychedelic philanthropists, investors, and companies commit 1% of their investment to support safety measures such as research and support services. The article outlines practical steps to make the field of psychedelic medicine safer.
Psychol Med
March 31, 2025
Otto Simonsson, Simon B. Goldberg, Walter Osika et al.
16 citations
In a large online survey of over 12,000 participants followed for two months, people who used psychedelics outside of medical supervision reported increases in psychotic and manic symptoms. These increases occurred only among those who used psychedelics in an illegal context. The severity of psychotic symptoms rose with more frequent use and more intense challenging experiences, while manic symptoms increased more in individuals with a history of schizophrenia or bipolar I disorder and those who reported a strong sense of insight during their psychedelic experience. The findings suggest that naturalistic psychedelic use in illegal settings may pose risks for certain individuals.
Journal of Psychopharmacology
November 30, 2016
Richard C. Shelton, Peter S. Hendricks
14 citations
No Summary
Journal of Drug Issues
August 30, 2019
Blake Beaton, Heith Copes, Megan Webb et al.
13 citations
People who microdose classic psychedelics such as LSD and psilocybin do not excuse their practice but instead justify it using six main strategies: denying that it causes harm, claiming it helps sustain themselves, pursuing self-fulfillment, appealing to normality, citing loyalty to valued groups, and emphasizing their knowledgeable. These justifications help align their actions with societal expectations. The findings come from interviews with 30 individuals who had microdosed.
Psychedelic Med (New Rochelle)
December 13, 2023
Nicholas A. Carlisle, Haley Maria Dourron, Sarah Maccarthy et al.
12 citations
Chronic shame, often stemming from internalized stigma, disproportionately affects sexual and gender minority (SGM) adults and undermines mental health. This theoretical and philosophical paper argues that psychedelic-assisted therapy holds unique potential to reduce such shame by disrupting rigid self-narratives and fostering self-compassion. The authors suggest that the pharmacological and contextual features of psychedelic experiences—particularly enhanced emotional openness and mystical-type experiences—may directly target shame-related neural and psychological processes. They propose that psychedelic therapy could offer SGM individuals a reparative pathway toward healing and psychological wellness, distinct from conventional treatments. The paper calls for further empirical investigation into psychedelics as a tailored intervention for chronic shame in this population.
Nature Mental Health
May 1, 2025
Daniel H. Grossman, Kevin R. Madden, Nicky J. Mehtani et al.
10 citations
Socioeconomic status (SES) strongly affects mental health outcomes and treatment access, but its reporting in psychedelic-assisted therapy trials is inadequate. A systematic review of 98 articles (49 primary trials and 49 secondary analyses) from 2006 to 2024 found that only 12% of primary trials reported participant income data, and 31% reported educational attainment. In US-based trials, participants had markedly higher SES than the general population: 93% had some college education (versus 62% nationally), and median incomes in major trials substantially exceeded the national median for all workers. Non-US trials showed variable patterns. This underreporting and evidence of socioeconomic disparities highlights an urgent need for standardized SES reporting and strategies to improve socioeconomic diversity in psychedelic-assisted therapy research.
JAMA Health Forum
November 1, 2024
Otto Simonsson, Matthew W. Johnson, Peter S. Hendricks
10 citations
Psychedelic and MDMA therapies carry potential risks that must be better understood to ensure safe and ethical practice. This viewpoint identifies four key research goals: characterizing adverse effects, understanding how context influences outcomes, developing risk mitigation strategies, and establishing guidelines for safe administration. The authors argue that rigorous investigation of these risks is essential before widespread clinical adoption, emphasizing that safety concerns should be addressed proactively rather than reactively.
Psychedelic Medicine
January 20, 2025
Marianna Graziosi, Gabrielle Agin-Liebes, Mary P Cosimano et al.
9 citations
Psilocybin and other serotonergic psychedelics are used in research settings with safety measures including controlled environments, staff presence, screening, and psychoeducation. An analysis of study materials from psilocybin trials over the past two decades found that psychoeducation documents varied but commonly emphasized biological and physical safety, psychological safety and well-being, aspects of setting, and the potential for expectancies. The materials prioritized biological and psychological safety across all sites. The authors also identified elements unrelated to safety that may contribute to participant expectancies and suggest these extrapharmacological factors be studied systematically to maximize safety while minimizing extraneous expectancies.