Autopsy and experimental studies have confirmed the concomitant coexistence of Aβ and tau pathologies in PD brains [19], suggesting their synergistic interactions, which can contribute to altering the progression of the disease [20,21,22], although one study suggested that cortical Aβ and tau did not relate to cognition in PD patients without dementia (PDND) [23]. Here, MAPT is linked to dementia.