A recent study (Ren et al., 2022) found that 40 mg/kg ketamine could induce delirium-like behavior in mice and increase the content of serum tau in endosomes, which is mainly responsible for the transport of intracellular goods, including proteins, lipids and nucleic acids that are important for cell function, and key for neurons to release tau protein (Elkin et al., 2016). Here, MAPT is linked to delirium.