MMP9 and Cognitive impairment: Interestingly, Mizoguchi and colleagues [10] have recently shown that Aβ-induced neurotoxicity in vitro as well as cognitive impairment in vivo is significantly alleviated by treatment with MMP inhibitors and significantly reduced in MMP-9 homozygous knockout mice, indicating that MMP-9 expression in the hippocampus might be involved in Aβ-induced cognitive dysfunction.