Neurodegenerative diseases as diverse as Alzheimer's, Parkinson's, and Creutzfeldt-Jakob disease share a common pathogenetic mechanism involving aggregation and deposition of misfolded proteins, which leads to progressive central nervous system disease. Although the type of aggregated protein and the regional and cellular distribution of deposition vary from disease to disease, these disorders may all be linked by similar pathways of protein aggregation with fibril formation and amyloid deposition. This perspective on pathogenesis suggests that a wide variety of neurodegenerative diseases can be grouped mechanistically as brain amyloidoses, an outlook that yields novel insights into potential therapeutic approaches that may be applicable across the broad spectrum of neurodegenerative disease.