MAPT and Alzheimer disease: In AD, it has been proposed that exosomes have a key pathological function in the progression of the disease, and are involved in Aβ and tau dissemination, since an accumulation of exosomes has been found in amyloid plaques (Rajendran et al., 2006) and hyperphosphorylated tau tangles (Saman et al., 2012, 2014; Levy, 2017).