RecruitingPhase 2Drug trial5-HTP and Creatine for Depression R33 PhaseThis is a three-armed clinical trial examining the effect of 5-hydroxytryptophan and creatine monohydrate as augmenting agents for the treatment of depression. Subjects will be randomized between 5-HTP 100mg BID + creatine 5g daily, 5-HTP 200mg BID + creatine 10g daily, vs double placebo, for 8 weeks. The ability of the interventions to affect biomarkers associated with depression will be assessed using brain phosphorus magnetic resonance spectroscopy, functional connectivity imaging, and plasma serotonin levels.