MMP9 and brain ischemia: Many studies indicate that cognitive dysfunctions may be associated with changes in MMP-9 activity [11, 17, 22–24], and show the importance of MMP-9 in cognitive dysfunctions of adult patients with dementia [19, 25], cerebral ischemia [11, 13, 14, 17] or neuropsychiatric symptoms in autoimmune diseases [16].