The Fisher’s Z-transformation analysis also showed significant between-group differences in correlation coefficients between the serum adiponectin levels and the [11C]PK11195 BPND values in the bilateral prefrontal (z score: left: −2.134; right: −2.330), anterior cingulate (z score: left: −2.320, right: −2.381), and temporal (z score: left: −2.256, right: −2.384) cortices (p < 0.05) (Table 4; Figure 4B), consistently indicating negative correlations in the MDD patients and positive correlations in the control subjects. This evidence concerns the gene ADIPOQ and major depressive disorder.