Potential predictors of depressive relapse following repetitive Transcranial Magnetic Stimulation: A systematic review

Background: Repetitive Transcranial Magnetic Stimulation (rTMS) is widely approved treatment for major depressive disorder (MDD). However, around 50% of individuals who recover from depression following rTMS interventions experience a relapse of depressive symptomatology by 12 months. The short-term durability of the rTMS treatment effect has been systematically investigated. However, variables relating to the long-term durability of the antidepressant effect produced by rTMS are less understood. Therefore, the current review systematically assessed the research on variables relating to relapse following rTMS. Method: This systematic review was performed according to PRISMA guidelines. A comprehensive electronic literature search for terms related to relapse following rTMS treatment for MDD was performed on studies published before the end of October 2018. Results: A total of 18 studies assessing relapse related variables were identified. While there is some indication that comorbid anxiety, acute response, and residual symptomatology may hold predictive potential for depressive relapse following rTMS treatment, findings were not sufficient to draw reliable conclusions. Discussion: Identified studies assessed three main categories of variables including demographic information, clinical characteristics and rating scale scores, and rTMS treatment specific factors. Only a small number of studies were available, and considerable inconsistency exists between studies, only limited conclusions were able to be drawn. Conclusion: More studies assessing a wider range of predictor variables such as cognitive or neuroimaging markers are needed.