Superior antidepressant effect occurring 1 month after rTMS: add-on rTMS for subjects with medication-resistant depression

Shaw-Ji Chen,^1,2 Chung-Hung Chang,³ Hsin-Chi Tsai,^2,4 Shao-Tsu Chen,^2,4 Chaucer CH Lin<sup>2,4

1</sup>Department of Psychiatry, Mackay Memorial Hospital Taitung Branch, Taitung; ²School of Medicine, Buddhist Tzu Chi University, Hualien; ³Department of Psychiatry, China Medical University Hospital, Taichung; ⁴Department of Psychiatry, Buddhist Tzu Chi General Hospital, Hualien, Taiwan

Abstract: Depression is a major psychiatric disorder. The standard treatment for depression is antidepressant medication, but the responses to antidepressant treatment are only partial, even poor, among 30%–45% of patients. Refractory depression is defined as depression that does not respond to antidepressant therapy after 4 weeks of use. There is evidence that repetitive transcranial magnetic stimulation (rTMS) may exert effects in treating psychiatric disorder through moderating focal neuronal functions. High-frequency rTMS on the left prefrontal area and low-frequency rTMS on the right prefrontal area were shown to be effective in alleviating depressive symptoms. Given the statistically significant antidepressant effectiveness noted, the clinical application of rTMS as a depression treatment warrants further studies. Application of rTMS as an add-on therapy would be a practical research model. High-frequency (5–20 Hz) rTMS over the left dorsolateral prefrontal cortex was found to have a significant effect on medication-resistant depression. In the present study, we not only measured the acute antidepressant effect of rTMS during treatment and immediately after its completion but also evaluated participants 1 month after completion of the treatment protocol. Study participants were divided into two groups: an active rTMS group (n = 10) and a sham group (n = 10). The active rTMS group was defined as participants who received the rTMS protocol, and the sham group was defined as participants who received a sham rTMS procedure. A significant Hamilton Depression Rating Scale score reduction was observed in both groups after the fifth and tenth treatments. However, those in the active rTMS group maintained their improvement as measured one month after completion of the rTMS protocol. Participants who received active rTMS were more likely to have persistent improvement in depression scores than participants who received sham rTMS.

Keywords: major depressive disorder, repetitive transcranial magnetic stimulation, treatment-resistant depression, efficacy, adverse effect