MAPT and synucleinopathy: One potential testable hypothesis could be that the aggregations and deposition secondary to cross-seeding of the pathologic proteins may be less toxic than the oligomers composed of pure tauopathies, or synucleinopathies, as the amyloid oligomers have emerged as the most toxic species of amyloid-β and tau oligomers may be more closely related to tau neurotoxicity than the presence of the tangles themselves [44, 45].