Transcranial Magnetic Stimulation Retreatment for Recurrent Depression: A Large Real‐World Multisite Cohort Study

INTRODUCTION: When depressive symptoms return after an initial response to transcranial magnetic stimulation (TMS), evidence to guide use of a second acute course is strikingly limited. We aimed to estimate how often and how quickly patients with recurrent major depressive disorder benefit from a second course of transcranial magnetic stimulation after they previously improved with TMS. METHODS: A retrospective cohort study across 20 outpatient centres included 259 patients who received ≥ 2 TMS courses between January 1, 2023 and October 1, 2025, and had clinically significant depressive symptoms at the start of course 2; 177 prior responders formed the primary cohort. Treatment used standard 10-Hz left dorsolateral prefrontal cortex TMS. Response and remission were assessed using the PHQ-9 and/or BDI-II; response was defined as a ≥ 50% reduction and remission as PHQ-9 ≤ 4 and/or BDI-II ≤ 9. Symptom change from baseline to end of course 2 and time to first response by session were compared between courses. RESULTS: Among past responders, 146 of 177 patients (82.5%; 95% CI, 76.1%-87.8%) responded again during course 2 and 96 of 177 (54.2%; 95% CI, 46.6%-61.7%) achieved remission. PHQ-9 scores decreased by a median of 65.0% (p < 0.001), and BDI-II scores decreased by a mean of 12.0 points (95% CI, -14.0 to -10.0; p < 0.001). Among responders, the first session meeting response criteria occurred earlier during retreatment than during the initial course on both PHQ-9 (median session, 12 vs. 16; hazard ratio = 1.40, 95% CI, 1.14-1.72; p = 0.001) and BDI-II (13.5 vs. 22.5; hazard ratio = 1.46, 95% CI, 1.07-2.00; p = 0.018). CONCLUSIONS: Most patients who previously benefited from acute TMS improved again when symptoms recurred, and among responders, the first session meeting response criteria often occurred earlier during retreatment than during the initial course.