Evaluation of Transcranial Magnetic Stimulation Efficiency in Major Depressive Disorder Patients: A Magnetic Resonance Spectroscopy Study

OBJECTIVE: Repetitive transcranial magnetic stimulation (rTMS) is an effective treatment for major depressive disorder (MDD). This study evaluated the antidepressant effect of rTMS and examined how it affected N-asetyl aspartate (NAA), choline (Cho), creatine (Cr), lactate (Lac), myoinositol (mIns), glutamate (Glu), glutathione (GSH), and glutamine (Gln) metabolite levels in the left dorsolateral prefrontal cortex (DLPFC) of MDD patients who were not receiving antidepressant medication. METHODS: In total, 18 patients (10 female, 8 male) were evaluated. Each patient underwent H magnetic resonance spectroscopy (H-MRS) before and within 3 days of completion of TMS therapy. All patients completed 20 sessions of rTMS directed at the left DLPFC over a 2-week period. The Hamilton Depression Scale (HAMD) scores of patients were calculated, and their responses to treatment were assessed within 1–3 days of completion of TMS. RESULTS: We found statistically significant differences in HAMD scores before and after rTMS. Moreover, the peak metabolite ratios of NAA/Cr, GSH/Cr, and Gln/Cr were significantly higher after rTMS compared to those before rTMS. CONCLUSION: Increased understanding of the mechanism of action of TMS will improve its application and may stimulate development of new-generation therapeutic agents.