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Journal of ECT:
doi: 10.1097/YCT.0000000000000094
Original Studies

Glutamate Alterations Associated With Transcranial Magnetic Stimulation in Youth Depression: A Case Series

Yang, Xiao-Ru BSc*; Kirton, Adam MD†‡; Wilkes, Thomas Christopher MD*†; Pradhan, Sarah*; Liu, Irene MSc§; Jaworska, Natalia PhD*; Damji, Omar MSc†‡; Keess, Jamie BSc†‡; Langevin, Lisa Marie PhD*; Rajapakse, Thilinie MD†‡; Lebel, Robert Marc PhD; Sembo, Mariko BSc*; Fife, Marilyn RN*; MacMaster, Frank P. PhD*†

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Abstract

Objective

We hypothesized an increase in dorsolateral prefrontal cortex (DLPFC) glutamate levels would occur after 3 weeks of repetitive transcranial magnetic stimulation (rTMS) treatment and a decrease in major depressive disorder (MDD) symptoms.

Methods

We report 6 patients (4 females) 15 to 21 years of age with treatment-resistant MDD. Participants had a mean (SD) age of 18.7 (1.95) years and a mean (SD) IQ of 102.3 (3.39). Short echo proton magnetic resonance spectroscopy (1H-MRS) was used to quantify glutamate levels in the left DLPFC (4.5 cc) before and after rTMS treatment. Repetitive transcranial magnetic stimulation was localized to the left DLPFC and applied for 15 consecutive weekdays (120% resting motor threshold; 40 pulses over 4 seconds [10 Hz]; intertrain interval, 26 seconds; 75 trains; 3000 pulses). Treatment response was defined as a greater than 50% reduction in Hamilton Depression Rating Scale scores. Short echo proton magnetic resonance spectroscopy data were analyzed with LCModel to determine glutamate concentration.

Results

After rTMS, treatment responders (n = 4) showed an increase (relative to baseline) in left DLPFC glutamate levels (11%), which corresponded to an improvement in depressive symptom severity (68% Hamilton Depression Rating Scale score reduction). Treatment nonresponders (n = 2) had elevated baseline glutamate levels compared to responders in that same region, which decreased with rTMS (−10%). Procedures were generally well tolerated with no adverse events.

Conclusions

Repetitive transcranial magnetic stimulation is feasible and possibly efficacious in adolescents with MDD. In responders, rTMS may act by induced elevations in elevating DFPLC glutamate levels in the left DLPFC, thereby leading to symptom improvement.

Copyright © 2014 by Lippincott Williams & Wilkins

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