MAPT and tauopathy: The discovery of extracellular tau as a physiological process that is independent of cell death (Pooler et al., 2013), indicates that tau release does not occur only as a result of reduced neuronal viability, and therefore that the increased tau observed in interstitial fluid and CSF in tauopathies may not be due solely to tau release from dying neurons (Yamada et al., 2011; Nedergaard, 2013).