High-Frequency Repetitive Transcranial Magnetic Stimulation Can Improve Depression in Parkinson's Disease: A Randomized, Double-Blind, Placebo-Controlled Study

Background: A recent evidence-based guideline demonstrated that bilateral repetitive transcranial magnetic stimulation (rTMS) over the motor cortex (M1) can improve motor symptoms of Parkinson's disease (PD). We conducted a randomized, double-blind, placebo-controlled study to evaluate the impact of bilateral M1 rTMS on depression in PD. Methods: Forty-six patients with PD and mild-to-moderate depression were randomly assigned to active (n = 23) and sham (n = 23) rTMS. Two patients in the sham group did not complete the protocol because of reasons unrelated to the study. High-frequency rTMS was applied over the primary motor cortex bilaterally for 10 days. An investigator blinded to the treatment performed three video-taped examinations on each patient: before stimulation (baseline), and 1 day (short-term effect) and 30 days after the treatment session ended (long-term effect). The primary end point was the changes in depression, while secondary end points included health-related quality of life scales and Movement Disorders Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS). Results: In the actively treated group, not only did the severity of depression improve (from 17 to 7 points, Montgomery-Åsberg Depression Rating Scale, median values, p < 0.001), but also the health-related quality of life (from 25.4 to 16.9 points, PDQ-39 summary index, median values, p < 0.001). Besides, we could also demonstrate an improvement in MDS-UPDRS Motor Examination (from 26 to 20 points, median values, p < 0.05). In the sham-treated group, none of the examined tests and scales improved significantly after treatment. Conclusions: Our results demonstrate the beneficial effects of high-frequency bilateral M1 rTMS on depression and health-related quality of life in PD. However, this effect of rTMS should also be confirmed in patients with severe depression by further clinical trials.