A measured exploration of psilocybin’s potential in navigating the unknown
In Canadian health research, there’s arguably no subject generating more public curiosity than psilocybin. Despite significant interest in the controlled substance’s potential therapeutic effects, the evidence base remains limited.
Dr. Sarah Hales, a psychiatrist and clinician investigator studying this topic at University Health Network (UHN), finds the intense public interest exciting, but it also gives her pause.
“There is a lot of hype, and in some ways that's great: it can facilitate attention. But we know things will swing the other way as so often happens, and we’ll see more criticism and scrutiny of the research in this space,” she explained.
“My goal is to try to explain where the science is to the public. To deflate some of the hype, but also speak about the opportunities, and put it in the context of the greater field of psychosocial oncology and existing evidence-based interventions.”
From research to relief
Dr. Hales is leading one of three clinical trials supported by the Psilocybin-assisted Psychotherapy funding opportunity from the Canadian Institutes of Health Research.
Her project focuses on patients in advanced stages of cancer. Dr. Hales’ team is exploring psilocybin’s potential use in conjunction with psychotherapy for distress from physical suffering, difficult treatment decisions, social difficulties, grief, and fear of death.
“We know psilocybin decreases barriers to thinking about and confronting things that have been frightening. The hope is that with support, people are then able to reflect on and deal with some of those fears and prepare better for the future.”
Building on an evidence-informed model
With a career dedicated to psychotherapeutic approaches to end-of-life support, Dr. Hales found complementary expertise in Drs. Emma Hapke and Daniel Rosenbaum, psychiatrists with a specific interest in psychedelics. The co-founders of UHN’s Psychedelic Psychotherapy Research Group serve as co-principal investigators on the project.
The trio got to work adapting the principles of Managing Cancer and Living Meaningfully (CALM), a proven intervention model co-developed by Dr. Hales. The result was a new psilocybin-specific model called ‘Psilocybin-assisted Existential, Attachment and Relational Therapy (PEARL)’.
Through PEARL, advanced-stage cancer patients experiencing distress will participate in eight psychotherapy sessions over the course of several months, with a single psilocybin-assisted session in the middle. The planned sample of 46 recruited patients will be randomized to receive a either a high dose of psilocybin (the treatment arm) or a low-dose control.
“I know a lot about psychotherapy and end of life, Drs. Hapke and Rosenbaum know a lot about psychedelics, and together we've been able to tailor an intervention that I think is going to be a good model,” said Dr. Hales.
At the intersection of science and spirituality
The established CALM model, she notes, incorporates an entire domain on spiritual and existential well-being.
“For many people, existential questions that arise in the face of dying and death can cause a lot of end-of-life distress.”
It’s an area in which the integration of psilocybin could prove particularly effective.
“One of the aspects of the psilocybin experience many people talk about is a sense of transcendence. We may be seeing that it's tapping into other aspects of experience more profoundly, another dimension in a sense, that's harder for psychotherapy alone to tap into.”
An abundance of caution
The project is currently in a pre-trial phase including intervention feasibility testing and the education of colleagues at the UHN’s Princess Margaret Cancer Centre. ‘Caution’ has been the central characteristic thus far.
“There have been lots of obstacles we didn’t imagine we would face, but in many ways, it’s a good thing,” Dr. Hales said.
“Safety is paramount, and in the end, the caution is going to be something that strengthens this work.”
The guarded approach stems in part from the relatively high-dose nature of these trials. Participants will be treated with 25 milligrams of lab-sourced psilocybin in a single session. It’s a figure informed by the dosages shown to be effective in previous clinical trials.
“It can be a very positive experience, but can also be very challenging, overwhelming or frightening,” Dr. Hales noted, a point she emphasizes when screening patients.
“They’ve maybe heard that this is just going to be a positive experience, but these aren't simply ‘happy pills’. Just like psychotherapy, it’s about creating an opportunity for people to confront what is difficult and maybe painful, with the hope that it can help them prepare for what lies ahead.”
The research team aims to complete feasibility testing of the intervention and begin recruiting for the trial in 2026. Interested individuals experiencing distress in the advanced stages of cancer can learn more about eligibility through the contacts on this UHN webpage.
“I wish I could set clear timelines, but it’s a complex trial involving both a psychological intervention and a medicine being delivered,” Dr. Hales explained.
“These are often very ill patients who are also in cancer treatment. What’s most critical is that we deliver a high-quality and safe study that we can feel confident about.”
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