Elevated VCAM-1 levels in peripheral blood are associated with brain structural and functional alterations in major depressive disorder

•The MDD exhibited decreased GMV in the right medial prefrontal cortex and postcentral, which were negatively correlated with VCAM-1.•The MDD showed increased FC between the left ventral prefrontal cortex and right inferior parietal lobe.•The VCAM-1 mediated the association between group and GMV/FC.•The vascular inflammatory factors are related to the brain regions with GMV/FC changes in patients with MDD.