GFAP and major depressive disorder: In view of the lower immunoreactivity of GFAP immunoreactive astrocytes and the lower levels of GFAP observed in the prefrontal cortex in postmortem human brains from younger subjects with major depression (as compared to older subjects or to non-psychiatric controls) (Miguel-Hidalgo et al., 2000; Si et al., 2004), early stress, adversity or excessive immune activation may prime astrocytes to facilitate, at least in some human subjects, manifestations of depression in late-adolescence and adulthood.