Scientists have discovered a new role for little-known brain cells called tanycytes that may influence the development of Alzheimer's disease. These specialized cells help remove toxic tau protein from the brain by transporting it from the cerebrospinal fluid into the bloodstream. When tanycytes are damaged or disabled, tau protein accumulates in the brain. Accumulation of tau is a hallmark of Alzheimer's disease. Thus, tanycytes play an important role in preventing this accumulation.