Motor threshold parameters do not predict repetitive Transcranial Magnetic Stimulation and intermittent Theta Burst...

Repetitive Transcranial Magnetic Stimulation (rTMS) and intermittent Theta Burst Stimulation (iTBS) are non-invasive treatments for major depressive disorder (MDD). While effective, variability in outcomes necessitates identifying predictors of therapeutic response. This study examined whether motor threshold (MT), percentage of motor threshold (%MT), and treatment intensity could predict clinical outcomes in MDD patients undergoing rTMS and iTBS.

Adult MDD patients treated with NeuroStar rTMS or iTBS at Mayo Clinic from February 2016 to April 2024 were included. MT, %MT, and treatment intensity were recorded. Clinical outcomes were assessed via Patient Health Questionnaire-9 (PHQ-9) score changes, response (PHQ-9 change ≥50 %), remission (PHQ-9 < 5), and a patient-reported outcome (PRO) on treatment helpfulness. Linear and logistic regression models were used to assess predictors of clinical outcomes.

Among 149 patients analyzed (mean age 45.7, 67.8 % female), response rate was 43.0 % and remission rate was 16.8 %. MT and %MT did not significantly correlate with clinical outcomes. Treatment intensity and TMS type did not predict PHQ-9 score changes. Higher treatment intensity was associated with decreased odds of positive PRO responses. Linear regression showed that age and gender significantly predicted PHQ-9 score changes, with older patients and females showing greater improvement. MT was significantly lower in men and with iTBS compared to rTMS.

MT, %MT, and treatment intensity did not reliably predict outcomes. Higher intensity was linked to reduced patient-reported helpfulness, suggesting that patient comfort is crucial. iTBS's lower MT may benefit those needing less stimulation. Future research should identify better predictors to improve TMS outcomes.