Electroconvulsive Therapy (ECT) is among the most effective treatments for treatment-resistant depression, but its use in bipolar depression is limited by cognitive side effects and stigma. Magnetic seizure therapy (MST) — which uses high-frequency repetitive transcranial magnetic stimulation rather than direct electrical current to induce a therapeutic seizure — has emerged as a potentially cognitively safer alternative. Its induced electric field is considerably more focal than ECT's, thought to spare medial temporal structures implicated in ECT-related memory impairment (though this mechanism is inferred, not directly tested here). Prior work supported MST's antidepressant efficacy and cognitive safety in major depressive disorder, but head-to-head data in bipolar depression had been lacking.

The CORRECT-BD trial was a double-blind, randomized, parallel-group pilot RCT conducted at four Canadian academic centers. Adults with bipolar I or II disorder in a non-psychotic major depressive episode (HAM-D >21) were randomized to right unilateral ultrabrief-pulse ECT (RUL-UB ECT; n=27) or MST (n=28). Co-primary outcomes were HAM-D remission (score ≤10 with ≥60% reduction on two consecutive assessments) and autobiographical memory worsening (≥25% AMT decline). Treatment continued until remission, dropout, or 21 sessions.

In the completer sample, remission rates were 30% for ECT and 20% for MST; response rates (≥50% HAM-D reduction) were nearly identical at 50% vs. 48%. ITT remission rates were 22% and 18%, respectively. These findings reflect descriptively similar antidepressant effects, though the study was not powered for noninferiority testing. On the primary cognitive outcome, clinically meaningful autobiographical memory worsening occurred in 22.2% of ECT participants vs. 7.1% of MST participants (ITT). Mean AMT scores fell from 9.05 to 7.57 following ECT and remained essentially unchanged following MST (9.18 to 9.19). Broader cognitive measures — verbal and visual memory, executive function — followed the same pattern, worsening post-ECT and remaining stable or improving post-MST. Time to reorientation averaged 19 minutes with ECT vs. 7 minutes with MST. Suicidal ideation remission was identical between groups (40% each), and quality of life improved in both. All four serious adverse events occurred in the ECT group.

Limitations include COVID-19-related disruptions to treatment delivery and cognitive assessments, limited statistical power, and a sample that was younger, more treatment-resistant, and exclusively non-psychotic compared to earlier ECT trials — factors likely contributing to the modest remission rates seen in both arms.

This pilot trial offers the most rigorous comparison to date of RUL-UB ECT and MST in bipolar depression. MST produced descriptively similar antidepressant effects with a meaningfully better cognitive safety profile. For patients reluctant to pursue ECT due to cognitive concerns, MST may represent a promising alternative — though confirmatory trials with larger samples are needed.

Reference:
Blumberger DM et al. Am J Psychiatry . 2026 May 6. Epub ahead of print. Abstract