The main conclusions of this work are as follows: (a) brain Aβ, tau, and p-tau were elevated in SAMP8 mice compared to control and increased with AD progression; similar, although slower, accumulation kinetics were found in RBCs; (b) α-syn and its heterocomplexes, α-syn-Aβ and α-syn-tau, showed different accumulation kinetics in brain tissues and RBCs; and (c) both brain and peripheral IL-1β levels were elevated in SAMP8 mice, but increased earlier in RBCs. Here, MAPT is linked to Alzheimer disease.