STAT1 and Alzheimer disease: The tendency for up-regulation of STAT1 and STAT2 protein levels in the entorhinal cortex of the DS-AD group, with the significantly higher STAT2 in DS-AD females compared to AD and control females, is consistent with increased background activity of the interferon system and up-regulation of ISGs in DS, which, in turn, may limit the infectivity levels at the initial stages of infection.