Research suggests that repetitive Transcranial Magnetic Stimulation (rTMS) is effective, safe, and proven treatment option for patients with treatment resistant major depressive disorder (MDD). Success rate is high, around 65–70% nationwide. Around 30% patients are still not responding to the treatment. Objective of this study is to evaluate the cause of treatment failure or non-responsiveness of TMS treatment despite high efficacy of the therapy. This is the first study to evaluate the cause of treatment failure of TMS therapy.

Retrospective, 16months, post- TMS treatment, Clinical rating scales PHQ-9 and GAD-7.

68 patients who got treatment over 16months were included in the study, inclusion criteria for thisstudy

includes patients with primary diagnosis of MDD, have previously received at least 20 TMS treatments

and must be evaluated with at least two clinical rating scales that were entered each day during treatment.

Number of treated patients:68

Patients responded to treatment: 50 (73.5%)

Patients not responded: 18 (26.4%)

Mean # of treatments received:37

Mean Baseline PHQ-9 Score:19

Mean Outcome PHQ-9 Score:7

To evaluate the cause of treatment failure in 18 non-responsive patients, patient charts were reviewed in detail. Patients were interviewed near the end of treatment, during follow-ups, and over the phone. It was established that they were either misdiagnosed, have symptoms of other psychiatric disorders such as bipolar depression, have dual diagnoses (e.g: MDD with anxiety, OCD, PTSD) or unclear diagnoses and in need of further psychiatric evaluations. The variety of these diagnostic scenarios mentioned are not typically treated with TMS therapy or treated differently with TMS as compared to MDD, hence the explanation of therapy failure.

Number one cause of TMS treatment failure is misdiagnosis due to various reasons. That includes failure to be accurately diagnosed by a primary psychiatrist, as those patients did not have primary psychiatrist and were referred by primary care physicians and were getting treated for MDD without a proper psychiatric evaluation and diagnosis. However, due to the limitations of the study due to small sample size, we propose that further investigations are needed to be replicated in larger patient population.