(TRD) a major personal and economic burden. Repetitive transcranial magnetic stimulation. (rTMS) is an emerging intervention for TRD in adolescents. Though ...
Possible Predictors of Response to Transcranial Magnetic Stimulation in Adolescent Treatment Resistant Major Depression Yamile Jasaui, Adam Kirton, T. Christopher Wilkes, Rose Swansburg, Frank P. MacMaster Department of Psychiatry, Paediatrics, Clinical Neurosciences; University of Calgary Introduction Major depressive disorder (MDD) has a very high impact on society, and usually develops during adolescence. It is estimated that approximately 15% of youth experience MDD, however, not all patients respond to treatment. Currently, 60% respond to pharmacological and psychological interventions but remission rates remain as low as 40%, making treatment-resistant depression (TRD) a major personal and economic burden. Repetitive transcranial magnetic stimulation (rTMS) is an emerging intervention for TRD in adolescents. Though rTMS is an effective technique, positive responses are not universal. As MDD is associated with alterations in brain chemistry, we investigated metabolite concentrations as a biomarker for predicting treatment response. We hypothesized that lower baseline glutamate levels would predict beneficial rTMS treatment response and associate with lower MDD scores post-treatment. Objectives To determine the association between left dorsolateral prefrontal cortex (DLPFC) glutamate levels, cortical thickness, and cerebral blood flow (CBF) with MDD symptomatology changes post rTMS intervention. Methods 24 youth with TRD underwent 3 weeks of rTMS, baseline and post-intervention magnetic resonance imaging scans, and short echo proton magnetic resonance spectroscopy. Response was determined by a 50% reduction of depression scores. Results Overall, rTMS resulted in a decrease in depression severity (Hamilton Depress ion) (t = 7.67, p < 0.001). Responders had lower left DLPFC glutamate concentration at baseline (t = 1.94, p = 0.03) compared to non-responders: this change in glutamate correlated with the change in depression severity (r = 0.46, p = 0.047). Reduced DLPFC thickness was observed in responders (t = 4.03, p = 0.001) and was associated with greater change in depressive severity (r = -0.80, p = 0.008). Lower left DLPFC cerebral blood flow at baseline was also associated with greater change in depression severity. Conclusion Measures of glutamate, cortical thickness and cerebral blood flow in the left DLPFC may provide tractable predictions of rTMS treatment response in youth. The development of biomarkers for rTMS response represents a novel and useful technique to provide personalized and effective treatment for adolescents with MDD.
