What are tau proteins? I heard that they are associated with alzheimer's.

See below. It is a microtubule proteins that are found inside neurons, it allows for stablility and flexibility of filaments. But when it becomes less flexibility, it can result in the self assembly of tangles from different kinds of filaments. Another word, tau proteins becomes tangles, a pathologic response as a result of neurodegenerative disease, including alzheimer's disease.