These findings contrast with a prior study that found no difference in TSPO binding between MDD subjects and healthy controls [19]; however, our study differs from that one in that we had a larger sample (n = 48 vs 22), with depression that was more severe (average MADRS = 31.5 vs 19.7) and current (in the previous study, some MDD participants had no current symptoms). Here, TSPO is linked to depressive symptom measurement.