MAPT and Alzheimer disease: However, t-tau/Aβ42 and p-tau/Aβ42 ratios provided higher diagnostic accuracy than SNAP-25 alone for AD (p = 0.044 and p = 0.038, respectively) (Table 2 and Fig. 5b) but not pMCI (p = 0.06 for both) (Table 2 and Fig. 5a).