The Current - A "major milestone" for treating severe depression

Episode Date: April 16, 2026

Scientists have the results of the first ever large-scale clinical trial of a new form of treatment for severe, treatment-resistant depression, called magnetic seizure therapy. They found it's as effective as electroconvulsive therapy (ECT), which is currently considered the gold standard. We talk to Dr. Daniel Blumberger of the Centre for Addiction and Mental Health in Toronto, also the co-lead of the study, about how this treatment can change lives.

Hi, Steve Patterson here, host of The Debaters, part stand-up, part quiz show, and part comedy competition. We take on the most pressing questions on the minds of all Canadians, like, is carpet superior to hardwood? Listen to the debaters, wherever you get your podcasts, and prepare to be, well, floored. This is a CBC podcast. Hello, I'm Matt Galloway, and this is the current podcast. There is a particular group of people with severe depression who have it worse, than others. It is estimated that about one in three of them don't seem to respond to antidepressant medication or psychotherapy, and the debilitating symptoms persist. The so-called gold standard treatment

for that up to now has been electroconvulsive therapy or ECT, but that therapy can have side effects, memory loss, chief among them, which is why scientists have been searching for alternatives. Now, the results of a new clinical trial are out showing promise for an option called MST or magnetic seizure therapy. Dr. Daniel Blumberger is a senior scientist at the Center for Addiction and Mental Health in Toronto, lead researcher on this study. Dr. Good morning. Good morning. Thank you for having me. Thanks for being here. What is MST? So magnetic seizure therapy is a treatment similar to ECT where a magnetic field is used to stimulate the brain and a pulse of stimulation between two and 10 seconds is delivered under anesthesia, and this stimulates the brain and induces a short

seizure that lasts between 15 and 90 seconds. And by causing a seizure, we cause the brain to get stronger and resist the depressive circuits that end up taking hold in people who are suffering from treatment-resistant depression. How is MST different from ECT? So by using a magnetic field, you can stimulate the brain without causing the electrical field to get into the areas of the brain that cause the memory side effects. So the stimulation is much more focal and it doesn't induce the side effect of memory impairment that can come with some people who receive ECT. So you're still triggering those seizures, but it's a much more targeted approach. Exactly. It's a much more focal stimulation that targets the depression circuitry, specifically. specifically rather than getting carried to areas of the brain that are involved in memory.

What does that treatment look like? Can you describe what it's like? So patients come in for treatment two to three times per week. They receive a general anesthesia. They're monitored. Their heart rate and blood pressure and oxygen saturation are monitored. They're given a very small dose of anesthesia and muscle relaxant. And the stimulation is delivered under anesthesia. And as I said, the stimulation lasts between two and 10 seconds. And a very very short seizures induced and people regain their breathing and and are going to a recovery room and take about 15 to 20 minutes to recover from the treatment and then they go about the rest of their day. And the sense is that this helps to treat severe depression because it, walk me through

this again, it strengthens part of the brain. Exactly. So by making the brain better at resisting some of the depression circuits that take hold, that's what ends up treating the depression. What researchers have found is that in depression, the circuitry gets bigger. And by delivering the stimulation, the brain gets stronger at resisting those depressive circuits. The work that we're talking about here when it comes to MST, this was part of this large-scale clinical trial, the first of its kind, right? So many smaller studies have been done that really demonstrate that MST clinically can treat the depression without the memory side of effects that some people experience when they receive ECT. And that's the reason that we've done

this large-scale study across sites in California and in Texas to really confirm what some of these smaller studies have found. And the results do confirm those findings that MST works as well as ECT, but has virtually no memory side effects compared to ECT. How significant can those memory side effects be with ECT? So what we tell people is that about most people experience some impairment in their memory in the three to six months before they received the treatment and three to six months after. And it's generally for things that happened around the time of the treatment and can go back in time by several months, sometimes a little bit longer. And that for some people is very disruptive. But we have to weigh this in the context of depression.

Depression is a lethal illness and it is the major cause of suicide. And what studies have shown is that ECT works better than any other treatment at reducing the risk of suicide. If you have a severe depression and are admitted to the hospital, if you have a course of ECT during your admission, you're 50% less likely to die by suicide. And that's really significant. What people forget about depression is that it can lead to death. And so we need newer treatments and we need treatments that are better tolerated. How do people, because you also treat people with ECT, how do those patients generally feel about going through that?

I think people are afraid of ECT. There's a lot of stigma associated with ECT. It's still an extremely effective treatment. And for people who have suffered with non-response to multiple treatments and are really struggling and the depression is so severe and they're having thought, about not wanting to live. Patients consider the treatment, but they're afraid of it, and they're afraid of what might happen to some of their memory and cognition.

And so are there people who perhaps could benefit from ECT but don't undergo that treatment because they're worried about those side effects? Exactly. And that's the population that we are really interested in this treatment. The numbers are staggering, that about only 1% of people who could benefit from ECT. benefit from ECT actually receive it. So there's a huge population who could benefit but don't consider it and don't receive it because of the fears, because of the stigma associated with ECT, and because there are

some memory side effects. What is your sense as to why it's taken so long to find something beyond ECT that would treat that severe treatment-resistant depression? Well, we're living in an age where there's multiple new treatments coming out. There are other treatments on the horizon and are currently being implemented into clinical care. There's treatments like transcranial magnetic stimulation. There's treatments like IV ketamine. But all of these new treatments require large-scale studies, and developing that evidence, it takes time.

And that's been the case with magnetic seizure therapy. The first treatments took place in the early 2000s, and it's taken more than 20 years to get to a place where we have enough clinical evidence to say that, it is as effective as ECT, but it has a better side effect profile. In the meantime, while those treatments are being developed, and the ketamine therapy is something that a lot of people have been paying attention to as well. Those patients are living through agony, right? Absolutely. And while there is hope, we need to improve the access to some of these newer treatments.

What would this mean if MCT is as promising as the study seems to suggest? What would that mean for your patients? Well, what we're really trying to do is translate these findings into clinical practice, and that's going to take an additional amount of work. We have to convince regulators to approve the treatment. We have to convince Health Canada that it's a device that should be approved and get a license. Once those things fall into place, it could potentially be incorporated into clinical practice. The thing about MST is it can be used in wherever ECT is currently used with some very minor modifications. But you're very cautious in saying that there are a lot of steps to be taken before MST can be made available to people.

Well, I'm cautious in that. I know that government approval and regulators take time. And sometimes, you know, while the evidence exists, it takes advocacy and efforts to really convince regulators to approve new treatments. But in the meantime, that urgency remains in place. As you said, that people who are living with severe treatment-resistant depression are at risk of death. Absolutely.

And that's why we need to advocate that these treatments don't take five, ten, 15 years to get incorporated into treatments and that we convince governments and regulators to approve these treatments when the evidence is there. Can that just ask you finally? We just have a couple of minutes left. What is your sense, are we getting better at understanding how to treat something that, not as untreatable, but has that enormous effect on people? There are other treatments to your point that are being considered right now.

And are we getting a better sense as to understand how to make people's lives better? Yeah, I think we're getting closer to understanding when to pick some of these newer treatments and when to integrate them into the care pathways. You know, I think we have medications. We have things like cognitive behavioral therapy. Repetitive transcranial magnetic stimulation is being incorporated into clinical practice. And people are now able to study these two treatments against each other. And we understand where in the pathway some of these new treatments should be tried. And on the other front, researchers are really working on picking treatments based on each individual person's brain pathology.

you know, depression is different in each individual person. The underlying biological manifestation is different. And so with some of the tools that we have, we might be able to pick patients based on their underlying pathology and deliver them the specific treatment. This is the promise of good news, and I'm glad to talk to you about it. Dr. Daniel Bloomberg, thank you very much. Thank you for having me. Dr. Daniel Bloomberg is a senior scientist at the Center for Addiction and Mental Health in Toronto,

his research into magnetic seizure therapy. MST for severe depression was published yesterday in the journal Lancet Psychiatry. This has been the current podcast. You can hear our show Monday to Friday on CBC Radio 1 at 8.30 a.m. at all time zones. You can also listen online at cbc.ca.ca slash the current or on the CBC listen app or wherever you get your podcasts. My name is Matt Galloway. Thanks for listening. For more CBC podcasts, go to cbc.ca.ca.com. podcasts.