Length of illness in MDD subjects was not related to TSPO binding (sgPFC: r = .15, p = .46; ACC: r = .13, p = .52), and in MDD, TSPO binding did not correlate with MADRS score (sgPFC: r = − .09, p = .65; ACC: r = − .11, p = .56). Here, TSPO is linked to major depressive disorder.