APP and neurodegenerative disease: Interestingly, several proteins associated with other neurodegenerative diseases of protein misfolding accumulate in damaged axons including amyloid precursor protein (APP), which is used as a diagnostic marker of DAI [45], its cleavage product Aβ, presinilin-1, phosphorylated tau, and the Parkinson’s disease associated protein α-synuclein [46].