Any person with stage four colon cancer deals with anxiety, but for the first few years after his diagnosis in 2016, Thomas Hartle considered himself to be managing pretty well. In part, this was because his Pet scans suggested the cancer wasn’t progressing rapidly.That changed in 2019, when a colonoscopy found tumors on his large intestine that the scans had missed. A follow-up surgery found dozens more. His relative calm evaporated.“Finding out that the best diagnostic tool wasn’t doing the job, that was disconcerting for me,” said Hartle, who is 56 and lives in Saskatoon, Canada. He felt death closing in on him from all sides. In November of 2019, his mother-in-law suddenly died. His father-in-law, who also had cancer, died the following month. The next spring, Hartle’s father died, then his niece, of adrenal cancer.“It was this impending feeling of, ‘Who’s next?’” he said.For days on end, Hartle would sit alone, overwhelmed, in a darkened room. At other times, his anxiety was so crushing that he needed someone to accompany him at every moment. “Maybe one of my intestines is going to rupture today, and I had to have somebody near me in case it does,” Hartle said. “In both of those cases, I wasn’t being present for what was going on in my life.”Then, he came across a 2016 study from Johns Hopkins University on cancer patients taking psilocybin, the active ingredient in magic mushrooms. According to the study, 80% of those who got a high dose of psilocybin felt less anxious and depressed. Hartle connected with TheraPsil, a non-profit that helps sick people in Canada receive legal permission to try psilocybin.In 2020, Hartle had his first psilocybin session with TheraPsil’s founder, the physician Bruce Tobin. He felt himself disappear: an experience as close to death as one can have while still being alive, he said. After it was over, instead of being afraid of the inevitable outcome of his illness, he felt relief. “It gave me a taste of what life after life could be like,” he said. “Instead of the idea that the lights shut off, the party’s over, it was like a transition from one state to another. That was really comforting to me.”Larger studies are under way to see if psilocybin could be a tool regularly used for palliative care, to ease the dying process. But researchers are still asking: how exactly does psilocybin help people confront their demise? Does it have to do with the sense that came to Hartle – that there is something that comes after life?An uncertain mechanismIn many ways, the renaissance in psychedelic research was born from the studies on terminal cancer patients at Johns Hopkins and New York University (NYU). The writer Michael Pollan covered one such study in the New Yorker, and his subsequent book, How to Change Your Mind, shot up bestseller lists and re-introduced the mainstream to the idea of psychedelics as medical treatments.Psychedelic drugs, like psilocybin, are currently the subject of intensive scientific research for their benefits in treating depression, PTSD and addiction. In cancer patients, like the studies Hartle came across, psilocybin has been shown to reduce existential distress.But a question remains: how?Thomas Hartle says psilocybin helped address his fear of death. Photograph: Courtesy Thomas HartleChris Letheby, a philosopher at the University of Western Australia, has spent years thinking about how psychedelics, like psilocybin, can make people feel better. In his 2020 book, The Philosophy of Psychedelics, he proposed that what psychedelic drugs do is change people’s “self-representation”.“The brain has this model of the self, and in some conditions, it can get dysfunctional,” he said, pointing to conditions that can follow, such as depression, PTSD or addiction. When people take psychedelic drugs, many of them report mystical experiences that are ineffable, ego-dissolving or spiritual. Letheby had suggested these experiences allowed a person to alter their self-perception. They came to view themselves, for example, as worthy of love from others, able to kick addictions and overcome past trauma. This tracked with studies that showed that having psychological insights about oneself or an emotional breakthrough during a psychedelic experience could predict good outcomes.But this explanation didn’t quite fit when it came to end-of-life anxiety.“It’s not clear exactly how you could get over your fear of death just by changing how you see yourself,” Letheby said.He became aware of newer research, from Sam Moreton, an associate lecturer at the School of Psychology at University of Wollongong in Australia, who has found that it’s not psychological insight but the mystical experience itself that is best associated with reductions in fear of death.In a recent paper, Letheby contradicted what he had previously claimed. He now believes psychedelics might work uniquely on people facing death. At end-of-life, psychedelics don’t help by altering self-representation, but by shifting fundamental beliefs, in some cases imbuing people with spiritual beliefs. Philosophers call this “metaphysical belief change”, and it can encompass ideas about the afterlife, spirits, consciousness or the nature of the universe.This tracks with reports from clinical trials. In a qualitative study based on interviews with NYU study participants, half of the participants said they went to a realm that existed at the time of or after death. “It does help you accept death because you don’t feel alone. You don’t feel like you’re going to, I don’t know, go off into nothingness,” one person said.Another described feeling discomfort in her stomach, which is where her tumor was located. “I kind of felt like that was my umbilical cord to the universe and that this was where my life would be drained from me someday, and I would surrender it willingly when my time came, and that was just so profound … It was just really comforting. It reaffirmed what I believe – that we’re all kind of a greater whole and that you go back.”‘The idea that life ends seems a little silly’In the United States, there is a continuing legal battle brought by a palliative care physician who wants to prescribe cancer patients psilocybin as part of end-of-life care. It is currently in appeals. Psilocybin is an illegal schedule 1 drug, and the only way for palliative care patients to access it is in research trials. There are bureaucratic hurdles in Canada, too, but more flexibility; Hartle was able to get what’s called a subsection 56(1) class exemption, which is valid for one year and extends to recipients outside formal trials.During his first experience, Hartle listened to music with his eyes covered with a blindfold. “‘Thomas’ as an entity completely ceased to exist,” he said. “I couldn’t remember that I had a family, let alone their names or faces. I was just existing in this other state.” As he describes it, with every song he saw a different universe, a musical world, his consciousness embedded inside that universe.skip past newsletter promotionafter newsletter promotion“It showed me how my consciousness could exist in a way that still had continuity to it, but had nothing whatsoever to do with” material life, he said.During the year he was approved for the therapy, Hartle took psilocybin twice more. After his exemption expired, he participated in the Roots to Thrive program, a Canadian non-profit that provides group and individual psychedelic programs for people dealing with terminal illness diagnoses, through similar legal loopholes.Pam Kryskow, a physician and the co-founder of Roots to Thrive, said that in her experience, people come to the program with a variety of hopes. Some people want to forgive themselves as parents, or confront the grief of no longer being able to do what they loved. Some need help to deal with their fear, the pain of their sickness, and there are those who want to address past trauma so they can show up for their families in their final months or years of life.Several studies of psilocybin for palliative care are taking place, including new trials at Dana-Farber Cancer Institute and the University of California, Los Angeles. Stephen Ross, an associate professor of psychiatry at NYU Grossman School of Medicine who helps oversees the university’s research on psychedelic medicine, has a grant from the National Cancer Institute to begin a larger study of psilocybin-assisted psychotherapy in people with advanced cancer. He is starting another on early-stage cancer patients, with a focus on women living with fear of breast cancer recurrence.Ross co-authored the NYU cancer patient study and said it was transformative for him. It shone a light on a part of medicine that doesn’t get much attention: what can be done for people who can’t be cured. “When I was in medical training, I never learned how to help a patient have a good death,” Ross said.After his first trip, Hartle’s wife, two children, family, and friends immediately noticed he had changed. His anxiety symptoms lessened and he participated more in everyday activities such as making dinner and playing with his kids.“I used to not be sure how life after life could be possible, in a physical sense,” Hartle said. “Now I very much feel that this body, this entire life that we experience here, is just a teeny part of our actual experience. The idea that life ends seems a little silly.”The ethics of changing beliefsIf there is no life after death, is it ethical for a doctor to encourage those beliefs in a dying person? The question is at the center of the “comforting delusion objection”, a concern over the implications of treatments that introduce false beliefs in order to work.Hartle has participated in several programs allowing access to psilocybin. Photograph: The Washington Post/Getty ImagesLetheby, who has described himself as a materialist, thinks that if psychedelics help people with existential distress by changing their beliefs, physicians should communicate this to patients. “It might turn out that that sacrifice is worth it,” Letheby said. “My point is just that it is a sacrifice, and we shouldn’t pretend it’s not. Acquiring false beliefs or losing true beliefs about reality shouldn’t be something that we’re just kind of sanguine about or just blindly ignore.”Importantly, a shift in metaphysical beliefs may not always be comforting. If a person left a psychedelic experience with a radically different understanding of the universe that contradicted their previous beliefs, that could be upsetting and destabilizing. In the recent study from Moreton and his colleagues, they did find that some people, about 17%, had their fear of death increased from a psychedelic experience.“We have seen people who have reported increases in death anxiety in the surveys that we’ve done,” Moreton said. They’re doing a follow-up study now on why people feared death more, or why they had trouble integrating their experience into their lives.I asked Hartle what he thought about his experience potentially being a “comforting delusion”. He laughed. “If somebody gives me a sugar pill, and my cancer improves, I don’t care,” he said. “I sincerely feel the same way about this. If this gives me what I believe is a glimpse into the afterlife, and that gives me comfort, reduces my anxiety, allows me to live in the present moment with my family and enjoy the time that I have, I don’t care about the source of that. I don’t think it matters.”In total, he’s now had seven high-dose mushroom experiences. Each has had similar themes: the music transports him, and he is not a part of his body or self any longer. He said that the effects were profound, but could wear off, which was why he had gone back to remind himself of the feeling that the trip generated.“The end is still going to be whenever the end is going to be,” he said. “But I’m not fixated on the dying part of it, I’m more fixated on the living part of it – experiencing the life that I’ve got left, instead of being so wrapped up in the idea that I’m going to die that I miss out on the life that happens between now and then.”