ADIPOQ and major depressive disorder: The correlation analysis in the MDD group with BMI as a covariate showed significant negative correlations between the serum adiponectin levels and the [11C]PK11195 BPND values in the left hippocampus (r = −0.433, p = 0.030) and right hippocampus (r = −0.564, p = 0.003) (Table 4; Figure 4A).