Magnetic Seizure Therapy Promising for Major Depression

Megan Brooks

November 02, 2012

High-frequency magnetic seizure therapy (MST) is a promising treatment for patients with treatment-resistant major depressive disorder, new research shows.

A small pilot study conducted by investigators from the Monash Alfred Psychiatric Research Centre (MAPrc) in Victoria, Australia, showed that MST had antidepressant effects without apparent cognitive side effects often seen with modern electroconvulsive therapy (ECT).

"MST involves the induction of a seizure through the use of magnetic stimulation, rather than direct electrical current, as occurs with ECT," MAPrc deputy director Paul B. Fitzgerald, PhD, who led the study, told Medscape Medical News. MAPrc is the only center in Australia conducting trials with MST.

The MST Treatment Team — (from left to right) Anne Maree Clinton, Dr. Kate Hoy, Dr. Paul Fitzgerald

"Magnetic fields," said Dr. Fitzgerald, "are able to pass freely into the brain, making it possible to induce a more focal seizure expression than in ECT. The use of direct electrical current in ECT leads to a much more widespread seizure induction, and it is this widespread effect that is thought to be responsible for the cognitive problems that can be seen following ECT. Therefore, MST appears able to spare the brain of cognitive effects due to its more focal effects on brain activity."

Mark George, MD, distinguished professor of psychiatry, radiology. and neurosciences at the Medical University of South Carolina in Charleston and member of the American Psychiatric Association, who was not involved in the study, told Medscape Medical News that modern ECT is currently "our most effective" treatment for treatment-resistant depression.

ECT, he said, can be "a lifesaver; it works, and it works fast, but in many patients there is transient amnesia. Clearly, we'd rather have something that is as effective but doesn't affect short-term memory at all."

The study was published online October 18 in Depression and Anxiety.

The pilot study involved 13 patients with moderate to severe depression who did not respond to adequate courses of 2 different antidepressants. They received 100-Hz MST for up to 10 seconds 3 times a week for up to 18 treatment sessions.

At the end of treatment, 5 patients (38.4%) met clinical response criteria, defined as a greater than 50% reduction from baseline to end of treatment on Montgomery-Ǻsberg Depression Rating Scale (MADRS) scores. For the group as a whole, the baseline MADRS score was 39.0 and fell to 26.5 (P = .007) after treatment.

There was also a significant group reduction in the Hamilton Depression Rating scale score (P = .008), the Beck Depression Inventory score (P = .012), and the Brief Psychiatric Rating Scale score (P = .019). "There was an overall group reduction in depression severity and no evidence of any impairment in orientation, memory, or other elements of cognition after MST treatment," the researchers write.

Pioneering Work

However, they point out that the antidepressant effects produced with MST in this study were not as marked as the commonly described ECT clinical response rate of 70%.

But Dr. Fitzgerald is far from discouraged.

"It's relatively early in the development of MST as a treatment for depression," he said. "We still need to explore the optimal methods of stimulation, including defining the optimal treatment site as well as the patients who are most likely to benefit from this treatment. Hopefully, as these questions are resolved, the overall response rate will improve."

Dr. George said this is "pioneering work and very important and the fact that they didn't see any cognitive side effects is great."

However, the efficacy results are "kind of disappointing," he said. "They only had 2 remitters (about 20% remission rate). With ECT in its modern form, we typically get a 60% to 70% remission rate. So MST is not ready for prime time yet."

Still, Dr. George emphasized that MST is "most certainly" worthy of further study and refinement.

Right now, "we don't fully understand how it works. I think you have to produce not only a seizure but a seizure in a certain circuit, and I think that is the prefrontal cortex," he said. The current study provided stimulation at the vertex.

Imaging Results

In addition to the study published in Depression and Anxiety, Dr. Fitzgerald and colleagues have also published imaging results from a pilot trial in a separate article, published online in Psychiatry Research: Neuroimaging .

"The imaging results showed that treatment with MST resulted in increases in the relative cerebral metabolic rate in limbic cortical regions (namely, basal ganglia, orbitofrontal, medial frontal, and dorsolateral frontal cortex)," first author Kate E. Hoy, PhD, told Medscape Medical News.

"They also indicated that antidepressant response to MST appears to be due to a restoration of balance within limbic-cortical brain regions, rather than an overall increase in brain activity in these areas. Previous research has shown these brain regions to be of considerable importance in both the pathophysiology and treatment of depression," Dr. Hoy said.

These observations, she added, are "an important initial step in understanding how MST is having an antidepressant effect. Future research will continue to focus on neurobiological effects of MST and will use specialized neuroscience techniques in order to more directly assess brain activity (including electroencephalography and transcranial magnetic stimulation)."

The study was funded by beyondblue: the national depression initiative and by the National Health and Medical Research Council. Dr. Fitzgerald has received equipment for research from Magventure A/S and Brainsway Ltd. Complete author disclosures are listed with the original articles. Dr. George has disclosed no relevant financial relationships.

Depress Anxiety. Published online October 18, 2012. Abstract