The results of this meta-analysis strongly indicate elevated binding of TSPO in all investigated regions in MDD patients vs. healthy controls, which suggests neuroinflammation extending across a range of cortical brain regions previously implicated in executive function (prefrontal cortex), mood (anterior cingulate, hippocampus), sensory processing and homeostatic state (insula), and affective processing (temporal lobe). Here, TSPO is linked to major depressive disorder.