MAPT and Alzheimer disease: A significant negative association was found between tau‐PET measure and CSF NPTX2 levels (β (SE) = −0.22 (0.06), p < 0.001, Figure 4D) both in the whole cohort as well as within the AD group alone (β (SE) = −0.27 (0.09), p < 0.01, Figure 4F); however, no significant associations were found in the control group (β (SE) = 0.01 (0.01), p = 0.27, Figure 4E).