MMP9 and nervous system disorder: A number of studies have shown that MMPs have a detrimental effect in neurological diseases and that MMP inhibitors can help reduce the injury.[10, 17, 18] During an acute stroke, there is disruption of the BBB with breakdown of extracellular matrix and tight junction proteins by MMPs, particularly MMP-9.[8] In an animal model of chronic stroke with features similar to patients with VCID, treatment with two relatively selective MMP-9 inhibitors failed to show improvement in MRI parameters and behavioral measures.