Symptom Trajectories Remained Consistent Across Initial and Repeat TMS for Depression, but Shorter Intervals Accelerated Response

Background: Transcranial magnetic stimulation (TMS) is effective for treatment resistant major depressive disorder (MDD).However, the trajectory of symptom change (TSC) during TMS needs further exploration.Here, we investigated TSC and correlation between trajectory and various intervals during two TMS courses.Methods: We retrospectively analyzed 43 patients with MDD who completed two 36-session TMS courses with serial PHQ-9 assessments.Scores were aligned to baseline and sessions 6, 12, 18, 24, 30, and 36.Symptom trajectories were compared using linear mixed-effects models with random patient intercepts (PHQ ~Timepoint Course).The interval between courses (GapDays; median 379 days, mean 447, IQR 312-527, range 177-1688) was examined across courses and within the second course.Endpoint response (50% PHQ-9 reduction) and remission (PHQ-9 4) at session 36 were assessed using paired McNemar tests.Predictive associations were evaluated with Fisher's exact test.Results: Across 560 observations, PHQ-9 scores improved significantly over time (F(6,504)=129.45,p <0.001).No main effect of course (F(1,505)=1.41,p=0.24) or Timepoint Course interaction (F(6,504)=0.44,p=0.85) was observed, indicating indistinguishable trajectories.GapDays did not influence final outcomes.Within Course 2, however, GapDays moderated early improvement (F(6,228.7)=2.59,p=0.019), with longer intervals linked to slower early reduction.Response rates were 78.0% and 77.5%, and remission rates were 36.6% and 32.5% for Courses 1 and 2.Discussion: This study is limited with retrospective design and self-report instruments.Based on this dataset, repeat TMS shows symptom trajectories and outcomes comparable to the initial TMS course.Shorter intervals may accelerate response without affecting final efficacy.