In April 2025, Greg Rennie, a 61-year-old man who has battled bipolar depression for nearly 30 years, sought treatment through a clinical trial at the University Health Network (UHN) that evaluated the safety and effectiveness of repeated ketamine infusions. Rennie rated his depression as an eight out of ten before his first ketamine infusion, but right after the treatment, his rating dropped to zero.
During the infusion, which involved being connected to an IV, Rennie experienced a sensation of floating and dissociation, likening it to being in outer space. He reported seeing a dark room that at times was penetrated by light, interpreting this experience as a representation of his own depression. Rennie stated, “I realized what it was showing me is that this is your depression. That I’m in this black box,” emphasizing how the treatment profoundly impacted his understanding of his mental health.
The results of the clinical trial, published in JAMA Psychiatry, indicated a significant improvement in the depressive symptoms of over 35 percent of participants who underwent two 40-minute ketamine infusions over a two-week period. In contrast, fewer than 12 percent of those in the control group receiving benzodiazepine as a comparison showed similar improvements.
Dr. Joshua Rosenblat, a psychiatrist and senior author of the study, highlighted a critical finding: the ketamine infusions did not trigger any manic episodes, psychosis, or suicidal thoughts among participants, which had been a major concern for patients with bipolar disorder. He noted, “What we found was that with each subsequent dose there were more and more benefits,” underscoring the potential therapeutic impact of ketamine.
Historically, individuals with bipolar depression have been excluded from ketamine treatment due to concerns about the possibility of transitioning from a depressive state to mania. However, Dr. Jennifer Swainson, a psychiatrist not involved in the study, suggested that the trial results indicate that this concern may not be significant, at least not beyond what may occur naturally within the course of the illness.
Ketamine, initially used as an anesthetic during surgeries for decades, has been increasingly utilized in low doses over the past 20 years to treat severe depression and other mental health disorders. There is a pressing need for effective treatments for bipolar depression, especially considering that about one in three patients do not respond to standard treatments and some medications can exacerbate their conditions. Current statistics estimate that approximately three percent of Canadians experience bipolar disorder.
Concerns regarding the potential for ketamine treatment to lead to addiction have surged, particularly following the overdose death of actor Matthew Perry, who was using the drug legitimately for depression but reportedly sought illicit doses from a dealer. Nonetheless, experts like Dr. Swainson contend that most individuals who use ketamine for depression do not present a high risk for abuse; many patients describe their experience with the drug as neutral or even unpleasant, yet they continue to use it as it provides relief.
A significant barrier to the wider accessibility of ketamine treatment is the fact that it is not covered by most provincial health insurance plans. While some clinics may cover a limited number of treatments or provide access through clinical trials, private community clinics often charge substantial fees. For instance, a full cycle of six treatments can cost up to $4,200. Following the trial, Rennie was referred to a private clinic where he continues to receive ketamine infusions every couple of months at a cost of $500 per session.
Rennie lamented the high cost of treatment, asserting that such therapy should be covered and readily available across Canada: “That’s the sad part of it. I think that has to change.” The trial's data indicating that symptoms returned after cessation of infusions suggests a need for ongoing maintenance sessions to maintain the antidepressant effects.
