In this study, we examined how FC of the Hb and NAc, key nodes of reward circuitry implicated in the neurobiology of depression (Gold & Kadriu, 2019; Proulx et al., 2014; Yang et al., 2018), are perturbed by SKI treatment in participants with TRD, and associate with improvements in mood and anhedonia. This evidence concerns the gene GSTM1 and major depressive disorder.