Richard Yensen

Richard Yensen
Born~1946 or 1947 (age 78–79)
Other nameRichard Yensen Pérez-Venero
EducationUniversity of California, Irvine
OccupationPsychotherapist
Years active1972–present
Employer(s)Johns Hopkins University, Harvard Medical School, University of Maryland, Multidisciplinary Association for Psychedelic Studies, Lykos Therapeutics
Organization(s)Orenda Institute; Heart of the Shaman
Known forWork with entactogen- and psychedelic-assisted therapy
SpouseDonna Dryer Pérez-Venero
Websiteresearchgate.net/profile/Richard-Yensen
orenda.org

Richard Yensen is an American–Panamanian psychologist and psychedelic drug researcher.

He was a research fellow at the Maryland Psychiatric Research Center (MPRC) of the Spring Grove Hospital from 1972 until its closure in 1976. Yensen studied psychedelic-assisted psychotherapy under Stanislav Grof at the MPRC and did his 1975 Ph.D. dissertation on 3,4-methylenedioxyamphetamine (MDA)-assisted psychotherapy through the University of California, Irvine. Along with Claudio Naranjo, he is one of the foremost pioneers of entactogen-assisted psychotherapy.

Yensen has taught at Harvard Medical School, Johns Hopkins University, and the University of Maryland Medical School. His wife is psychiatrist and psychedelic drug researcher Donna Dryer. Yensen developed a novel non-drug shamanistic form of psychotherapy known as perceptual affective therapy. The Yensens are the founders and directors of the Orenda Institute, a psychedelic-assisted therapy organization aimed at continuing the work of centers like the MPRC. In the 1990s, the Yensens attempted to launch government-approved studies of LSD-assisted psychotherapy for treatment of alcoholism and other uses in the United States (FDA IND 3250), but this was ultimately unsuccessful and they soon opted to move to Canada instead.

Subsequently, the Yensens worked in the Canadian phase 2 clinical trials of MDMA-assisted psychotherapy for post-traumatic stress disorder (PTSD) conducted by the Multidisciplinary Association for Psychedelic Studies (MAPS) and Lykos Therapeutics (now Resilient Pharmaceuticals) in the 2010s. They are said to have been leaders of the trial they were involved in. In 2018, Meaghan Buisson, a patient in one of the trials treated by the Yensens and a world record-holding former speed-skater, filed a complaint and civil lawsuit against the Yensens in 2018 alleging misconduct by the couple and sexual abuse by Yensen. This included inappropriate physical contact such as cuddling and spooning during psychotherapy sessions in which she was under the influence of MDMA, the couple bringing Buisson to live with or near them on Cortes Island, British Columbia for further therapy, and Yensen having sex with her under the guise of it being exposure therapy for her PTSD. Buisson has said that Yensen also administered her drugs like ketamine during therapy sessions outside of the trial and pursued sex with her while she was intoxicated.

Buisson's lawsuit alleged repeated sexual assault by Yensen and the case was settled out of court in June 2019. The Yensens have been unrepentant and have blamed Buisson for the events or have declined to comment. MAPS and others have referred to Yensen's actions as "sexual abuse" or "sexual misconduct". Police recommended criminal charges against Yensen, but prosecutors declined to pursue them, with their prosecutory standards requiring a "substantial likelihood of conviction". Dryer also gave up her medical license as a result of the incident in 2023. Among other amends, MAPS cut ties with the Yensens following the events. The Yensens have faced lawsuits from multiple past psychedelic-assisted therapy clients.

The Yensens have run a private retreat or workshop called Heart of the Shaman on Cortes Island, British Columbia.

Selected publications

See also

References

  1. 1 2 3 Greenstien, Kayla; Hall, Will (18 December 2024). "Set, Setting, Forgetting: Silence on Abuse in Psychedelic Therapy Histories". Mad In America. Retrieved 19 June 2026.
  2. 1 2 3 Wolfson, Phil (17 July 2024). "A Therapist Responds to the MDMA Imbroglio". Lucid News - Psychedelics. Regarding the woman who was sexually abused while still a subject in a MAPS Phase 2 study at its Canadian site, it was me and my partner who discovered the sexual misconduct. We were visiting our long time friends, a female psychiatrist and her husband, an unlicensed near 70 year old psychologist of renown. Both had been leaders of the study, and both were treating the patient in their home, this being the case while the sexual relationship with the male was ongoing.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 13 Wolfson, Philip E. (1 July 2014). "Psychedelic Experiential Pharmacology: Pioneering Clinical Explorations with Salvador Roquet (How I Came to All of This: Ketamine, Admixtures and Adjuvants, Don Juan and Carlos Castaneda Too): An Interview with Richard Yensen". International Journal of Transpersonal Studies. 33 (2): 160–174. doi:10.24972/ijts.2014.33.2.160. Retrieved 19 June 2026.
  4. 1 2 3 4 "Cautionary Tales: MDMA & MDA in Psychotherapy – Multidisciplinary Association for Psychedelic Studies – MAPS". Multidisciplinary Association for Psychedelic Studies – MAPS – Psychedelic Research for Psychological Healing. 12 May 2016. Retrieved 19 June 2026.
  5. 1 2 3 4 5 Goldhill, Olivia (3 March 2020). "Psychedelic therapy has a sexual abuse problem". Quartz. Retrieved 19 June 2026.
  6. 1 2 3 4 5 6 Harrison TR, Faber SC, Zare M, Fontaine M, Williams MT (January 2025). "Wolves Among Sheep: Sexual Violations in Psychedelic-Assisted Therapy" (PDF). Am J Bioeth. 25 (1): 40–55. doi:10.1080/15265161.2024.2433423. PMID 39804304.
  7. 1 2 3 4 Shorto, Russell (4 September 2012). Saints and Madmen: How Science Got Religion. Open Road Media. ISBN 978-1-4532-6591-8. Retrieved 19 June 2026.
  8. 1 2 3 4 Almendro, Manuel (25 May 2023). The Labyrinth of Ayahuasca. Cambridge Scholars Publishing. p. 102. ISBN 978-1-5275-0501-8. Retrieved 19 June 2026. being revealed. The researchers mentioned above expanded their work in the transpersonal field, as did Richard Yensen (1999) and Donna Dryer.5 I see Richard and Donna occasionally, and on one of my visits to their Orenda Center in Baltimore, they were frustratingly waiting for the U.S. government to send them doses of LSD. Soon afterward, they moved to Canada.
  9. 1 2 3 4 5 6 Chris Aiken (10 June 2024). "MDMA: What Went Wrong Part 1". The Carlat Psychiatry Podcast (Podcast). Carlat Publishing. The media coverage has portrayed Richard Yensen – the male therapist – as an unlicensed therapist working at a low level in the MAPS trial. That is not the case. Richard is unlicensed, but he has practiced psychedelic therapy since the 1970's as a licensed psychologist. He has directed institutes and taught at Harvard and Johns Hopkins. He helped develop MDA – a predecessor of MDMA – and lectured on how to avoid boundary violations during MDMA therapy. He is a giant in the field – someone who helped develop many of the therapeutic techniques in use today. Someone whom the US FDA has trusted with drug permits for investigational studies into LSD.
  10. 1 2 3 Hagerty, Lawrence (2000). The Spirit of the Internet: Speculations on the Evolution of Global Consciousness. Matrix Masters, Inc. p. 40. ISBN 978-0-9703651-1-8. Retrieved 19 June 2026.
  11. 1 2 3 Yensen, Richard; Dryer, Donna (1997). "Update: LSD Research at Orenda Institute". MAPS Bulletin. 7 (2). Multidisciplinary Association for Psychedelic Studies: 4.
  12. ↑ Yensen, Richard (1975). The Use of 3, 4 Methylenedioxyamphetamine (MDA) as an Adjunct to Brief Intensive Psychotherapy with Neurotic Outpatients (PDF) (PhD thesis). Irvine, California: University of California, Irvine. Archived from the original on 2026-06-19. Retrieved 2026-06-19.{{cite thesis}}: CS1 maint: bot: original URL status unknown (link)
  13. ↑ Passie, Torsten (29 June 2023). The History of MDMA. Oxford University PressOxford. doi:10.1093/oso/9780198867364.001.0001. ISBN 978-0-19-886736-4. Retrieved 19 June 2026.
  14. ↑ Passie, Torsten (2018). "The early use of MDMA ('Ecstasy') in psychotherapy (1977–1985)". Drug Science, Policy and Law. 4. doi:10.1177/2050324518767442. ISSN 2050-3245. Retrieved 19 June 2026.
  15. ↑ Baggott, Matthew John (Spring 2010). Other Times I Can Barely See: The Effects of Hallucinogens on Vision and Attention (Doctor of Philosophy in Neuroscience thesis). University of California, Berkeley. Claudio Naranjo [157] and Richard Yensen et al. [147] each explored MDA as an adjunct to psychotherapy, while Turek et al. [146] administered R-(-)-MDA and Shulgin and colleagues administered racemic and individual enantiomers [150, 158, 159] for experimental purposes.
  16. ↑ Kungurtsev, Igor; Luchakova, Olga (1 July 1992). "Meetings with Remarkable Men and Women". MAPS Bulletin. 3 (3): 14–16. Richard, when governmental polices made it impossible for him to continue his psychedelic research, created a system of sensory overload therapy which indudes a tremendous slide show. The set of slides is an artistic masterpiece. The selection and high frequency of slide changes induces an altered state close to an LSD experience.
  17. ↑ Yensen, Richard (1980). "Perceptual Affective Therapy" ( (PDF)). In Boorstein, Seymour (ed.). Transpersonal Psychotherapy. Palo Alto: Science & Behavior Books. Archived from the original on 2026-06-19. Retrieved 2026-06-19.{{cite book}}: CS1 maint: bot: original URL status unknown (link)
  18. ↑ Pellerin, Cheryl (3 November 1998). Trips: How Hallucinagens Work in Your Brain. Seven Stories Press. p. 176. ISBN 978-1-888363-34-0. Retrieved 19 June 2026. The relationship between peak experience and outcome in LSD psychotherapy with substance abusers. Investigators: Albert Kurland, M.D., Richard Yensen, Ph.D., and Donna Dryer, M.D.-M.P.H, Baltimore, Maryland. This FDA-approved study assesses the effect of different LSD doses on short-term intensive outpatient LSD therapy for drug abusers. The results should give valuable information about predictive factors for positive outcome. The goal is to determine relationships between peak experience as an objectively measured event in LSD psychotherapy, the number of exposures to LSD during psychotherapy and clinical improvement as objective measures of therapeutic outcome. Estimated annual cost: $100,000.
  19. ↑ Warren, Jenifer (16 April 1993). "LSD Makes a Return Trip : As Drug Reappears on the Scene, Many Warn of Risks". Los Angeles Times. In the years since, a small band of researchers who have refused to give up on LSD have been inching onward, hoping to regain government permission--and grants--to use it on human subjects. They have scored at least one important victory, winning approval in 1991 from the Food and Drug Administration for a study of LSD's effect on 60 drug addicts. Richard Yensen, one of the researchers who will conduct the study once funding is obtained, believes using humans to assess LSD is essential because "it is very hard to ask a rat what is happening in its consciousness."
  20. ↑ Dryer, Donna; Yensen, Richard (1 April 1993). "LSD Research in the '90s". MAPS Bulletin. 4 (1): 3–5.
  21. 1 2 3 4 Lindsay, Bethany (29 March 2022). "Footage of therapists spooning and pinning down patient in B.C. trial for MDMA therapy prompts review". CBC. Retrieved 19 June 2026.
  22. 1 2 Edwards, Bob (31 March 2021). "Meaghan Buisson Alleges Sexual Abuse During Psychedelic Therapy Trials". psychedelicobserver.com. Archived from the original on 16 June 2021. Retrieved 19 June 2026.
  23. ↑ Rosin, Hanna (22 March 2022). "You Won't Feel High After Watching This Video". The Cut. Retrieved 19 June 2026.
  24. 1 2 3 Jacobs, Andrew; Nuwer, Rachel (4 February 2025). "How a Leftist Activist Group Helped Torpedo a Psychedelic Therapy". The New York Times.
  25. 1 2 Worthington, Elise; Taylor, Kyle; King, Tynan (25 July 2022). "Meaghan thought psychedelic therapy could help her PTSD. Instead it was the start of a nightmare". ABC News. Retrieved 19 June 2026.
  26. 1 2 3 Lindsay, Bethany (18 March 2021). "As psychedelic therapy goes mainstream, former patient warns of danger of sexual abuse". CBC.
  27. ↑ Jacobs, Andrew (12 August 2024). "Three MDMA Studies Are Retracted by Scientific Journal". The New York Times. Retrieved 6 February 2025.
  28. 1 2 Lily Kay Ross and David Nickles (30 November 2021 – 22 March 2022). "Cover Story: Power Trip (Season 1)" (Podcast). Cover Story. Meaghan Buisson (interviewee in multiple episodes). New York Magazine, Psymposia.
  29. 1 2 "Statement: Public Announcement of Ethical Violation by Former MAPS-Sponsored Investigators – Multidisciplinary Association for Psychedelic Studies – MAPS". Multidisciplinary Association for Psychedelic Studies – MAPS – Psychedelic Research for Psychological Healing. 24 May 2019. Yensen and former sub-investigator Donna Dryer verbally confirmed that Yensen engaged in a sexual relationship with the participant. Sexual contact between therapy providers and participants is unethical conduct of sexual abuse in violation of Section 6 of MAPS Code of Ethics for Psychedelic Psychotherapy and generally accepted standards of care.
  30. ↑ Stone, Will (4 June 2024). "FDA advisers reject MDMA therapy for PTSD, amid concerns over research". Connecticut Public. "Let's try to not gloss over this misconduct. It was sexual misconduct. That's particularly important," said Joniak-Grant, a sociologist and a member of the [FDA advisory committee] panel.
  31. ↑ Halpern, Luke; Hippensteele, Alana (12 March 2025). "MDMA Rejected: The Story of a Study Participant Entrenched in Ethical Violations". Pharmacy Times. Retrieved 19 June 2026.
  32. 1 2 Busby, Mattha (20 June 2022). "MDMA trials under review in Canada over alleged abuse of study participants". The Guardian. Retrieved 20 June 2026.
  33. 1 2 Semley, John (29 July 2025). "Psychedelic Therapy Crashed and Burned. MAHA Might Bring It Back". WIRED. Like Doblin, Lubecky was optimistic that the treatment would get approved. But during the proceedings, a statement was entered into the record on behalf of a woman named Meaghan Buisson. In 2014, Buisson was recruited into a Phase 2 clinical trial run by MAPS. While under the influence of MDMA, she said, she had been "blindfolded, gagged, pinned, cuddled, and caressed" by the therapists, a married couple. She had attempted suicide afterward, she said; a doctor later told her she had effectively been "drugged, raped, blamed, and held as a sex slave." [...] In 2021, Psymposia and New York magazine coproduced an investigative podcast called Cover Story: Power Trip. One of its most damning episodes was deeply critical of MAPS and featured Meaghan Buisson—the woman whose story of assault came up in the FDA hearings.
  34. ↑ Browne, Grace (6 April 2023). "The Therapy Part of Psychedelic Therapy Is a Mess". WIRED. Retrieved 23 June 2026.
  35. ↑ Lindsay, Bethany (16 October 2023). "B.C. psychiatrist resigns licence after patient complains of abuse during psychedelic therapy study". CBC. Retrieved 19 June 2026.
  36. ↑ Kase, Holly (1 May 2024). "Psychedelic Sherpas: Can ketamine clinics serve as a model for psychedelic-assisted therapy?". Shoeleather Magazine. Today, Yensen and Dryer have faced multiple lawsuits from past psychedelic-assisted therapy patients, and Dryer has resigned her license.
  37. ↑ Lindsay, Bethany (30 October 2023). "Married B.C. therapists face another lawsuit over actions in MDMA therapy trial". CBC. Retrieved 19 June 2026.