Improving the antidepressant efficacy of transcranial magnetic stimulation: maximizing the number of stimulations and treatment location in treatment-resistant depression.

OBJECTIVE To assess the efficacy of increasing the number of fast left repetitive transcranial magnetic stimulations (rTMS) (10 Hz @ 120% of motor threshold (MT) over the left dorsolateral prefrontal cortex (DLPFC)) needed to achieve remission in treatment-resistant depression (TRD). And, to determine if patients who do not remit to fast left will remit using slow right rTMS (1 Hz @ 120% MT over the right DLPFC). METHOD Patients were part of a multicenter sham-controlled trial investigating the efficacy of fast left rTMS. Patients who failed to meet minimal response criteria in the sham-controlled study could enroll in this open fast left rTMS study for an additional 3-6 weeks. Patients who failed to remit to fast left could switch to slow right rTMS for up to 4 additional weeks. The final outcome measure was remission, defined as a HAM-D score of <3 or 2 consecutive HAM-D scores less than 10. RESULTS Forty-three of 141 (30.5%) patients who enrolled in the open phase study eventually met criteria for remission. Patients who remitted during fast left treatment received a mean of 26 active treatments (90,000 pulses). Twenty-six percent of patients who failed fast left remitted during slow right treatment. CONCLUSION The total number of rTMS stimulations needed to achieve remission in TRD may be higher than is used in most studies. TRD patients who do not respond to fast left rTMS may remit to slow right rTMS or additional rTMS stimulations.