α-Synuclein Fibrils Cross seed Tau Via LLPS In Alzheimer’s Disease With Lewy Body Co pathology. These two intracellular co-pathologies, tau and α-synuclein, can rarely interact within the cell; however, when they do, this interaction may aggravate disease progression by promoting tau aggregation and increasing the overall tau pathology through the liquid–liquid phase separation (LLPS) of α-synuclein fibrils and tau monomers.