Inherent pathologic features of “proteinopathy” (as exemplified by aSyn strain, or amount of co-existing AD pathology) are modulated by individual host features (genetic background and environmental exposures throughout life), resulting in varying cognitive presentations. PD-NC = Parkinson’s disease with normal cognition, PD-MCI = Parkinson’s disease with mild cognitive impairment, PDD = Parkinson’s disease with dementia, DLB = dementia with Lewy bodies.