Neurodegeneration and neuronal dysfunction in Parkinson’s disease (PD) occur before the involvement of alpha-synuclein (α-syn) positive pathway in the substantia nigra. Several studies have shown evidence of tau pathology in PD brain. Now, a study examined whether tau pathology plays a role in nigrostriatal degeneration before the involvement of Lewy pathology. Researchers analyzed brain tissues of individuals with or without mild motor deficits (MMD), which is insufficient to diagnose PD and individuals with PD.
Losses of nigral dopaminergic neurons, putamenal dopaminergic innervation, and the tyrosine hydroxylase-phenotype in the putamen and subtantia nigra were found in MMD groups with or without nigral α-syn aggregates. Notably, phosphorylated tau was found in similar degrees in both groups. These findings indicate that tau can initiate nigrostriatal dopaminergic neurodegeneration…
