MMP9 and Alzheimer disease: In the AD group, interaction of cortisol with MMP-9 showed inverse associations with CSO-PVS (p value = 0.0206, q = 0.08), with a positive effect of hippocampal volume (p value = 0.015, q = 0.08), indicating that at low levels of MMP9, higher levels of cortisol are associated with enlarged CSO-PVS and BG-PVS volume fraction; when MMP9 levels increase, higher levels of cortisol are associated with decreased PVS volume fraction.