MAPT and Lewy body dementia: The PGRN/t-tau ratio was significantly lower in prion diseases compared to the other groups (p < 0.0001) and significantly higher in FTLD-tau compared to AD (p = 0.0005) and DLB (p = 0.0224) and could differentiate FTLD-tau from AD and DLB better than t-tau (Fig. 1d).