MMP9 and Alzheimer disease: In the group of healthy elderly individuals we observed that the individuals with risk markers for possible future AD, that is AD-supportive CSF biomarkers (tau and Aβ42) or presence of the APOE ε4 allele, have higher CSF MMP-3 and MMP-9 levels and a higher CSF MMP-3/TIMP-1 ratio compared with the individuals without risk markers.