MAPT and Alzheimer disease: As discussed by Busche et al. (2019), studies have also showed a progressive reduction in whole-brain activity in AD patients (Silverman et al., 2001; Alexander et al., 2002; Greicius et al., 2004) and regional cerebral blood flow (Bradley et al., 2002) as well as an EEG slowing (Jelic et al., 1997), all of which could be explained by a dominant neuronal activity suppressive effect of tau.