Tissue Processing

All ET, PD, and 18 control brains had a complete neuropathological assessment at the New York Brain Bank. Brains had standardized measurements of brain weight (grams), and postmortem interval (hours between death and the completion of processing fresh brain into frozen tissues and placing remaining brain in formalin) (25). Whenever possible, 17 standardized blocks were harvested from each brain and processed, and 7-μm-thick paraffin sections were stained with Luxol fast blue/hematoxylin and eosin (LH&E) (5). In addition, selected sections were stained by the Bielschowsky method, and with mouse monoclonal antibodies to human glial fibrillary acidic protein (GFAP, clone GA5, Novocastra, Newcastle upon Tyne, UK), α-synuclein (clone KM51, Novocastra), phosphorylated tau (clone AT8, Research Diagnostics, Flanders, NJ), and β-amyloid (clone 6F/3D, Dako, Carpenteria, CA) (5). All tissues were examined microscopically by a senior neuropathologist blinded to clinical information including age and diagnosis (5). Brains had Braak and Braak Alzheimer disease staging for neurofibrillary tangles, and Consortium to Establish a Registry for Alzheimer’s disease (CERAD) ratings for neuritic plaques (26–29). Cerebellar tissues received from other brain repositories were from the same standard region as harvested at the New York Brain Bank.