RecruitingBehavioural interventionInflammatory and Glutamatergic Mechanisms of Sustained Threat in Adolescents With DepressionDespite the prevalence and significant public health concern over depression among adolescents, up to 40% of depressed adolescents do not respond to first-line antidepressants (herein termed treatment non-response, TNR). The goal of this project is to recruit and assess 160 treatment-seeking depressed adolescents and test whether acute stress impacts peripheral levels of inflammation and downstream levels of glutamate in corticolimbic regions previously associated with depression, whether these stress-related biomarkers predict TNR to a 12-week trial of either fluoxetine or escitalopram, and whether these stress-related biomarkers predict 18-month clinical course.