The Therapeutic Efficacy of Prefrontal Slow rTMS in Major Depression and Schizophrenia

Abstract

Recent studies have suggested that repetitive transcranial magnetic stimulation (rTMS) of the dorsolateral prefrontal cortex (DLPFC) might be effective as a treatment for major depression (MD). One line of studies has reported the efficacy of high-frequency rTMS (10-20 Hz) to the left DLPFC, using focal stimulation. Our work has focused on the evaluation of low-frequency (1 Hz) rTMS to the right DLPFC. Using this approach, rTMS has been shown to be significantly more effective than sham stimulation in a double-blind controlled study in 70 subjects with MD. At the end of ten daily rTMS sessions, Hamilton depression ratings (HDRS) were significantly lower in the rTMS group. Also, a significantly larger portion of patients had HDRS ratings < 10 and did not need electro convulsive therapy (ECT). In contrast, we failed to show therapeutic efficacy of rTMS in 31 schizophrenic patients using the Same treatment protocol. In a third study, 46 normal volunteers were assessed for neuropsychological effects of one session of low-frequency rTMS applied to the right or left DLPFC as compared to sham rTMS. In this double-blind study, rTMS did not appear to have any adverse cognitive effects as assessed by several neuropsychological tests. Taken together, these findings suggest that right prefrontal rTMS may be selectively effective in MD without noticeable neuropsychological adverse effects. These results should be viewed as preliminary, and further studies are necessary to assess the longterm efficacy and the optimal treatment parameters of rTMS in MD and possibly other neuropsychiatric disorders.