MAPT and Alzheimer disease: The seven healthy elderly individuals with an AD-supportive CSF biomarker pattern (CSF Aβ42/P-tau ratio <6.5 combined with CSF T-tau >350 ng/l [15]) had significantly higher levels of CSF MMP-9 (z = -2.37, P < 0.05; Figure 5) compared with the other 27 healthy elderly individuals.