SLC6A3 and depressive disorder: Mixed-effects model analysis of the relationship between striatal DAT SBR and depression symptoms across all time points revealed that the effect of MAO-B inhibitor treatment on motivation was moderated by striatal DAT SBR (β = −0.23, 95% CI −0.39 to −0.07, P = 0.006) (Table 3 and Fig. 3).