MAPT and Alzheimer disease: The cleavage of tau is a post-translational modification, which can affect tau function, with some fragments acting as seeds which promote tau aggregation,42 altered tau clearance, and, in vivo, changes in cognition and motor ability.43 Tau cleaved at both its N- and C-termini has been detected in AD brain.44 Currently, no consensus exists on whether intact, N-terminally or C-terminally truncated tau is the species of tau that propagates.