Sustaining the therapeutic effect of rTMS treatment through maintenance: A naturalistic study.

INTRODUCTION: Repetitive transcranial magnetic stimulation (rTMS) is effective for treatment-resistant depression (TRD), yet many responders relapse after an acute course of treatment. Maintenance rTMS, delivered over an extended period, has been proposed to sustain clinical benefits, although evidence remains limited. MATERIAL AND METHOD: In this retrospective study, we examined the effects of maintenance rTMS in 88 adults who achieved at least a 33.3% reduction in 9-item Patient Health Questionnaire (PHQ-9) scores following an acute rTMS course, a threshold chosen to represent a minimum clinically meaningful improvement and to include partial responders, responders, and remitters. Maintenance was defined as fewer than three sessions per week for at least two weeks. The mean maintenance duration was 5.7 weeks, with patients receiving an average of 7.8 sessions. RESULT: Depressive symptoms from the start of maintenance (SOM) treatment (PHQ-9: mean = 5.27, SD = 4.5) to the end of maintenance (EOM; PHQ-9: mean = 5.58, SD = 4.7) did not significantly worsen (β = -0.13 [-0.95, 0.71]). Exploratory meta-analyses on an expanded set of patient records (N = 97) indicated that smaller symptom improvements during acute rTMS (< 30% reduction in PHQ-9) and longer (> 4 weeks), more frequent maintenance sessions were associated with better outcomes from SOM to EOM. CONCLUSION: Although limited by its naturalistic and retrospective design, this study found that reduced-frequency early maintenance rTMS was associated with sustained therapeutic gains. However, causal conclusions regarding relapse prevention cannot be drawn, underscoring the need for prospective controlled trials to define optimal maintenance parameters.