Depressive symptom trajectories associated with standard and accelerated rTMS

Background: To determine if an accelerated rTMS protocol results in distinct depressive symptom response trajectories, compared to a standard rTMS protocol. We also sought to validate previous analyses that identified distinct depressive symptom response trajectories with rTMS treatment using an external dataset.

Method: Data from two recent clinical trials comparing accelerated rTMS protocol delivered to the left dorsolateral prefrontal cortex (DLPFC) with standard once-daily rTMS protocol were used to identify depressive symptom response trajectories. The accelerated protocol in Trial 1 was conventional 10-Hz rTMS, while Trial 2 employed intermittent theta burst stimulation (iTBS). Participants were adult outpatients (18-70 years old) with bipolar or unipolar depression and moderate-severe depression (Montgomery Asberg Depression Rating Scale score >19) who had failed to respond to adequate courses of two different antidepressants. We used group-based trajectory modeling to identify MADRS response trajectories, and regression techniques adjusting for baseline depressive symptom severity to determine the association between treatment protocol and depressive symptom response trajectory.

Results: Treatment outcomes of 189 participants were analysed. We identified four distinct response trajectories: "nonresponse" (N = 59; 30.7%), "minimal response" (N = 65; 34.1%), "higher symptoms, response" (N = 26; 14.6%), "lower symptoms, response" (N = 39; 20.6%). We failed to find an association between rTMS protocol (accelerated vs standard) with depressive symptom response trajectory even after adjusting for baseline depressive symptom severity.

Conclusion: The accelerated rTMS protocol in this study did not impact depressive symptom response trajectories. This work provides further confirmatory evidence that there are distinct depressive symptom response trajectories with rTMS delivered to the left DLPFC.

Australian new zealand clinical trials registry: ACTRN12616000443493 and ACTRN12613000044729.