This 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.