Everyone is talking about psychedelics, especially in the context of mental health. The growing interest reflects ongoing challenges in mental health treatment efficacy, particularly for conditions that do not respond to existing treatments.
Over the last decade, psychedelic medicine has received renewed scientific investment as researchers investigate whether compounds such as psilocybin (the psychoactive compound in “magic mushrooms”), LSD, and mescaline may help treat mental health conditions, including depression, post-traumatic stress disorder (PTSD), anxiety-related disorders, and substance use disorders.
One of the key areas of interest is whether psychedelic therapies may support neuroplasticity—the brain’s ability to adapt and reorganize itself over time. This capacity allows the brain to learn from experiences, form new habits, and adapt patterns of thought and behaviour. Researchers are exploring whether psychedelic compounds may support these processes and create new pathways for treating mental health conditions.
At the Centre for Addiction and Mental Health (CAMH), researchers are investigating how psilocybin interacts with the brain and whether changes in neural connections are linked to improvements in symptoms across various mental health disorders, including treatment-resistant depression, late-life depression, obsessive-compulsive disorder, and alcohol use disorder.
“In exploratory research, we can see the impacts of the drug on the brain even after the first use,” shares Dr. Gerasimos Konstantinou, Scientist and Psychiatrist at CAMH. “While more information is needed to understand deeper impacts of these changes, this research advances both our understanding of psychedelics and how changes in brain structure may be related to mental health.”
As Canada’s largest mental health research hospital, CAMH has become a leading contributor to psychedelic research in the country. In 2022, CAMH was the only Canadian site participating in the world’s largest clinical trial of psilocybin for treatment-resistant depression.
The study evaluated the safety and efficacy of psilocybin at various doses, with participants receiving psychological support before, during, and after treatment. Conducted across 22 sites in 10 countries, the trial contributed to growing evidence that psilocybin may have therapeutic potential for people who have not responded to existing treatments.
“At a glance, the results of the study may appear to be modest, but a response rate of almost 40 per cent, and a remission rate of almost 35 per cent of participants showing a total absence of depressive symptoms so rapidly with a single-dose treatment is actually very rare,” shares Dr. Ishrat Husain, Senior Scientist and Psychiatrist, CAMH. “When compared with similar testing on medications currently used for treatment-resistant depression, I would say that they are very encouraging.”
Later that same year, CAMH received Canada’s first federal grant to investigate whether the psychedelic effects, commonly known as the “trip,” associated with psilocybin are necessary for its therapeutic benefits.
“Currently, psychedelic therapies require extensive specialized psychological support and highly controlled clinical environments before, during, and after treatment,” shares Husain. “If we discover that psilocybin may have antidepressant effects without inducing a psychedelic state, it could reduce some of the resources required to administer the treatment, potentially making it more accessible for patients and healthcare systems.”
The CAMH-led clinical trial, “A Proof-of-Concept Randomized Controlled Trial to Show that the Antidepressant Effects of Psilocybin Do Not Require Psychedelic Effects,” enrolled more than 40 adults with treatment-resistant depression. Participants were assigned to different treatment groups, including one that received psilocybin alongside a medication designed to block its psychedelic effects. All participants also received psychotherapy, in line with current practices in psychedelic research.
Once the results are published, they will provide initial evidence of the antidepressant effects of this drug combination. The findings could help guide further research into whether depression can be treated with psilocybin without the need for intensive psychotherapy. Researchers are currently analyzing the study's results, and more information will be available in the coming months.
Building on this work, CAMH has expanded its research efforts through multiple studies, many conducted in partnership with University Health Network, exploring the safety and efficacy of psilocybin therapy for conditions including obsessive-compulsive disorder (OCD), alcohol use disorder, major depressive disorder, treatment-resistant depression, and bipolar depression.
Although psychedelic trials report promising results, researchers caution that this work is in the early stages and remains experimental, advising against self-medication. Published studies are conducted in highly controlled clinical settings with carefully selected groups of participants. People with personal or family histories of psychosis, for example, are often excluded from these studies due to potential risks associated with psychedelic substances. More evidence is needed to better understand the safety, efficacy, accessibility, and long-term outcomes associated with psychedelic use.
At CAMH, researchers are continuing to build this evidence through ongoing clinical studies, interdisciplinary collaboration, and investments in research infrastructure designed to support emerging areas of psychiatric science.
“Overall, this research is improving our scientific understanding of psychedelic therapies and their potential role in mental health care,” explains Husain. “Regardless of the outcome, this growing body of research is expanding what we know about brain function and neuroplasticity and may inform future treatment approaches.”
Now at Royal Ontario Museum — Psychedelics: Art. Culture. Science.
The Centre for Addiction and Mental Health (CAMH) is pleased to advise the Royal Ontario Museum (ROM) on an upcoming original exhibition titled Psychedelics: Art. Culture. Science. This exhibition delves into the various historic and current cultural practices from around the world associated with psychedelics, as well as their artistic and scientific dimensions. Visitors will learn about scientific theories regarding how psychedelics affect the brain, while also critically examining their risks and therapeutic potential.
Psychedelics: Art. Culture. Science. will run from June 6, 2026, to December 6, 2026. For more information, visit: https://www.rom.on.ca/whats-on/exhibitions/psychedelics-art-culture-science.
CAMH’s Psychedelics FAQ provides a brief, evidence-based overview of common questions about psychedelics and psychedelic medications, including what they are, how they work, and where our research stands today. Click here to visit our Psychedelics FAQ.
