In tauopathy the complement factors C1q and C3 are increased in the neural parenchyma and CSF of human AD subjects and in the neural parenchyma of mouse models of AD (Wang et al., 2011; Daborg et al., 2012; Hong et al., 2016; Dejanovic et al., 2018; Litvinchuk et al., 2018; Wu et al., 2019). Here, C3 is linked to tauopathy.