Treatment- Resistant Bipolar Disorder

The purpose of this trial is to determine if intermittent theta-burst stimulation (iTBS) can reduce the symptoms of depression in treatment-resistant bipolar disorder. To do this, some of the participants in this study will receive treatment with active iTBS stimulation, while others will receive sham iTBS stimulation. Participants will come for 30 days of either active iTBS or sham iTBS, with a 6-week follow-up period. Symptoms of depression (for determining treatment efficacy) and mania (for determining treatment safety) will be assessed using the 17-item Hamilton Rating Scale for Depression (HRSD-17) and the Young Mania Rating Scale (YMRS) every five treatments during the treatment course, and at 1 week and 6 week after treatment completion.