Caspase-Cleaved Tau Accumulation in Neurodegenerative Diseases Associated with Tau and α-Synuclein Pathology

Alzheimers disease (AD), Picks disease (PiD), progressive supranuclear palsy (PSP), corticobasal degeneration (CBD) and dementia with Lewy bodies (DLB) are diseases associated with the accumulation of tau or -synuclein. In AD, -amyloid (A)-associated caspase activation and cleavage of tau at Asp ⁴²¹ (Tau) may be an early step in neurofibrillary tangle (NFT) formation. To examine whether Tau accumulates in other diseases not characterized by extracellular A accumulation, we examined PiD, PSP, and CBD cases in comparison to those without extensive tau accumulation including frontotemporal lobar degeneration without Pick bodies (FTLD) and control cases. Additionally, we studied Tau accumulation in DLB cases associated with intracellular -synuclein. Tau was observed in all disease cases except non-PiD FTLD and controls. These results demonstrate that the accumulation of Tau may represent a common pathway associated with abnormal accumulation of intracellular tau or -synuclein and may be relatively less dependent on the extracellular accumulation of A in non-AD dementias.