ONE-BD: A Single-Day, Neuroplasticity-Enhanced TMS Regimen for Bipolar I Depression

Methods:We conducted a secondary analysis of 64 patients across three sites implementing FDA-cleared TMS protocols for treating depression: daily 10-Hz (n = 40) and accelerated-iTBS (n = 24).TMS-induced E-Fields were computed with MRI-based FEM models at the motor cortex (M1) and treatment target in the prefrontal cortex (PFC).Two metrics were calculated for each subject: PFC E-Field strength (V/m) and effective %rMT (percentage of M1-E-Field delivered to PFC).Clinical improvement was defined as percent reduction in depression score (PHQ-9 or BDI) from baseline to end-of-treatment.Relationships were analyzed using robust linear regression controlling for site, age, sex, and baseline severity.Results: Both metrics showed negative relationships with clinical improvement.PFC E-Field strength exhibited a consistent directional trend ( = -0.617,p = 0.114).Higher effective %rMT, which accounted for individual differences in cortical excitability, was significantly and inversely correlated with symptom improvement ( = -0.487,p = 0.009).Discussion: Lower relative stimulation intensities were associated with better clinical outcomes across protocols for depression.These retrospective findings warrant systematic investigation of TMS parameters in larger randomized trials.