Estrogen Metabolites, Oxidative Stress, and the Pathophysiology of Treatment-Resistant Depression

Introduction Major depressive disorder (MDD) is a heterogeneous and disabling illness, affecting more than 300 million individuals worldwide. Despite decades of research and the availability of multiple pharmacological classes—selective serotonin reuptake inhibitors (SSRIs), serotonin–norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants, monoamine…