Efficacy of Bilateral Dorsolateral Prefrontal Theta-burst Stimulation in Elderly Refractory Depression: a Randomized Sham-controlled Study

Thea-burst stimulation (TBS) is a novel form of rTMS, providing greater modulation effect on neural activity. So far, no study was conducted to use TBS as treatment in LLD. Therefore, we aim to examine the effect of TBS over bilateral dorsolateral prefrontal cortex (DLPFC) among patients with LLD on mood condition and relevant biomarkers. The study used a two-arm, parallel, double-blind, randomized, and sham-controlled design. We plan to enroll sixty patients with LLD, thirty for active intervention and thirty for sham-controlled group. An Magstim Rapid2 stimulator with eight-figure coil was used for stimulation. Location of brain area are based on bilateral DLPFC. 3-pulse 50-Hz bursts was given every 200ms (at 5 Hz) and an intensity of 80% active motor threshold was settled. We initially used cTBS (continuous TBS) over right DLPFC with 120-s train of uninterrupted bursts (1800 pulses) in each session per day. After that, we continuous use iTBS (intermittent TBS, iTBS) over left DLPFC with 2-s train of bursts was repeated every 10 s for a total of 570 s (1800 pulses). Each patient received daily stimulation for two weeks with total ten sessions. The primary outcomes were change of depression severity including response and remission rate. Secondary outcome were biomarkers related to depression. Assessments were administered at baseline, immediately after 5 and 10 sessions of stimulation, and 3 months after the completion of stimulation.