Tau-directed drug discovery for Alzheimer's disease and related tauopathies: a focus on tau assembly inhibitors.

The microtubule-associated protein tau forms insoluble filaments that deposit as neurofibrillary tangles (NFTs) in the brains of those with Alzheimer's disease (AD) and other related neurodegenerative disorders. The presence of both NFTs and amyloid beta (Abeta)-containing senile plaques within the brain is required to confirm the diagnosis of AD. However, the demonstration that familial AD can be caused by mutations that result in increased Abeta production has resulted in AD drug discovery strategies that are largely focused on reducing brain Abeta levels, with substantially less emphasis on tau-directed approaches. This trend may be changing, as there are an increasing number of research programs that are exploring ways to reduce NFTs in AD and related tauopathies. We briefly review recent advances in tau-based drug discovery, with an emphasis on the identification of compounds that inhibit the assembly of tau into multimers and fibrils.