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Dennis McKenna: Researcher for Psychedelic Medicines

Dennis McKenna: Researcher for Psychedelic Medicines
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Who is Dennis McKenna?

Dennis McKenna is the younger brother of Terence McKenna, a famous activist, professor, and proponent of psychedelics in the 1980s–90s who died in 2000. He is an ethnopharmacologist, lecturer, and psychedelic advocate in his own right. McKenna sits on the board of multiple significant psychedelic societies, including as a founding member of the Heffter Research Institute. Now, he focuses on advocating psychedelic-assisted therapeutics for mental health.

Early Life and Education

Travel and Study 

Dennis McKenna was born in 1950 in Colorado. He and his brother Terence were primed for the psychedelic awakening in the 1960s by a father who cultivated a love of science, science fiction, and alternative dimensions in his sons. McKenna first took LSD when he was 16. Terence, who was studying at UC Berkeley, introduced Dennis to DMT, which he describes as “the ultimate mystery.” His fascination with DMT led McKenna to study Jungian psychology, shamanism, ethnobotany, and anthropology. At age 20, he and his brother traveled to La Chorrera, Colombia, searching for a longer-lasting DMT-style hallucinogen called oo-koo-he. Instead, McKenna stumbled upon the intense spiritual qualities of psilocybin. The brothers turned their focus to mushroom cultivation. 

McKenna’s psychedelic experiences in La Chorrera sparked a hunger to understand the science of these psychoactive substances and their interaction with the brain. He received his master’s degree in botany from the University of Hawaii in 1979, and earned his PhD in botanical sciences from the University of British Columbia in 1984. There, his research focused on ethnopharmacological investigations of ayahuasca


McKenna has helped bring psychedelic research into many academic and private institutions. These include Stanford University, the National Institute of Mental Health (NIMH), Shaman Pharmaceuticals, and Aveda Corporation. He taught at the University of Minnesota until 2017. Recently, he started a new nonprofit, the McKenna Academy of Natural Philosophy, in 2019. He and his wife reside in British Columbia.

Mushroom Cultivation

Dennis McKenna and his brother Terence discovered that the hallucinogen they had been searching for was actually psilocybin. They also discovered that there was little knowledge about how to consistently grow the mushroom containing this desired compound. The two developed a reliable method for cultivating psilocybin mushrooms using the spores they brought back from Colombia. Then the brothers published Psilocybin: Magic Mushroom Grower’s Guide, under the pseudonyms O.T. Oss and O.N. Oeric in 1976. Providing “precise, no-fail instructions for growing and preserving the magic mushroom,” it gave home growers a step-by-step guide with a scientific foundation for growing mushrooms. It was the first guide to be widely publicized and sold at least 100,000 copies.

Dennis McKenna and Psychedelics

McKenna sees psychedelics as molecular tools to explore and understand the “brain-mind” interface. Despite his use of LSD and developing a fascination with DMT and psilocybin, his lifelong relationship with ayahuasca has made the most impact on him as a plant teacher. 

He first took ayahuasca at a Brazilian church in São Paulo. This experience created a new appreciation for photosynthesis and water’s life force. He interpreted the message as one of connection to the earth and a need to wake up to the destruction humans are inflicting on the planet. His fascination has always focused on science, with a particular interest in how plants communicate with each other and other species. 

McKenna told Joe Rogan on the Joe Rogan Experience podcast in 2014, “One of the problems with science is it tends to be arrogant and tends to assume it knows much more than it knows. We actually have a very detailed understanding of very small pieces of reality. So there is a tendency to say ‘Well, we’ve got it all figured out.’ Well, no you haven’t got it figured out. You haven’t got even a tenth of it figured out. Which is another useful message that ayahuasca and other psychedelics remind us of. You don’t know shit.” 

Psychedelic-Assisted Therapeutics

As mainstream channels begin to accept therapeutic psychedelics, McKenna is interested in exploring through rigorous science how they can help treat anxiety, addiction, and PTSD. McKenna coins the term “cathartogen” in describing psychedelics’ ability to induce catharsis. This is a powerful force in mental health and something traditional psychiatric medicines do not produce in their patients.

Ayahuasca Retreats

Ayahuasca has been integral to McKenna’s professional and personal life since he went to Peru for field work in 1981. Ayahuasca retreats (or “Ayahuasca tourism”), usually based in South or Central America, are growing in popularity among Westerners seeking to have an ayahuasca experience surrounded by traditional shamanic culture. 

While some have questioned the ethics of such retreats, McKenna doesn’t believe ayahuasca tourism is inherently good or bad. He believes in ayahuasca as a way for people to better themselves and create a better connection to the earth and spirituality. 

He is currently a retreat advisor for Soltara Healing Center in Costa Rica. In addition, he has organized retreats in other South American countries.

Top Dennis McKenna Quotes

“Our destiny, if we are to survive, is to nurture nature and to learn from it how to nurture ourselves and our fellow beings. This is the lesson that we can learn from ayahuasca, if only we pay attention.” — Ayahuasca and Human Destiny, The Journal of Psychoactive Drugs

“Ayahuasca, like anything else, is a technology. It’s a tool. It really doesn’t have any inherent moral qualities. It can be used in really positive ways and really negative ways because the ethics of it originate in the people who use it and how they use it and what they use it for.” —Ayahuasca is changing global environmental consciousness, The Guardian

“You monkeys only think you’re running things.” —Ayahuasca and Human Destiny, The Journal of Psychoactive Drugs

“Psychedelics are not suppressed because they are dangerous to users; they’re suppressed because they provoke unconventional thought, which threatens any number of elites and institutions that would rather do our thinking for us. Historically, those in power have always sought to suppress free thought, whether bluntly or subtly, because it poses an inherent challenge to their rule. That’s no less true today, in an age when corporate, political, and religious interests form a global bloc whose interests threaten all earthly life, including human life.”―The Brotherhood of the Screaming Abyss

“The message is basically “wake up!” You know, we’re wrecking the planet. I do think that my ayahuasca experiences and other experiences have led me to … the Gaia concept, the idea that the earth itself is an organism and that the earth itself is intelligent.” —What is Ayahuasca trying to teach us, Reality Sandwich

“l really think these plants are the way we communicate with the rest of the biosphere …I’m not speaking in any mystical sense here, I’m talking biochemistry. A good deal of human history is shaped by human interactions with plant secondary compounds” —Dennis McKenna Interview, Erowid

“We are made of drugs. We’re biochemical engines that run on drugs; neural transmitters, hormones, and all the signaling molecules that run the organism.” —Psychedelic Wellness is for Everyone, Reality Sandwich.

Notable Dennis McKenna Books

The Invisible Landscape: Mind, Hallucinogens, and the I Ching (1975)

Psilocybin: Magic Mushroom Grower’s Guide (1976)

Botanical Medicines: The Desk Reference for Major Herbal Supplements (2002)

The Brotherhood of the Screaming Abyss (2012)


What is Dennis McKenna known for?

Dennis McKenna is known for his method of psilocybin mushroom cultivation, developed in the 1970s, and his research on ayahuasca. He is also the brother of famous psychonaut Terence McKenna. He continues to be one of the leading voices in the science of psychedelics.

Is Dennis McKenna related to Terence McKenna?

Yes. Dennis McKenna is Terence McKenna’s younger brother. While Dennis never became as famous or as overt a counterculture hero as Terence, he is known in scientific circles for bringing psychedelic culture to the laboratory and exploring the benefits of psychedelic therapies.

Contributing Author: Jesse Klein

Jesse Klein is a science and outdoor reporter based in the Bay Area. She has written for VICE, New Scientist, Inside the Jar and many other national publications. Her background in neuroscience and experience as business journalist informs her reporting as she dives deep into the science, policy and business of drugs and psychedelics. See more of her writing at as well as on RS writing about the Shroom Boom and much more!

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