S100B and Alzheimer disease: Furthermore, changes in S100β levels have been identified in AD patients: while S100β is strongly overexpressed in AD hippocampal and temporal lobe astrocytes closely associated with either diffuse or neuritic Aβ plaques, only moderate increases have been found in frontal lobe and pons and unchanged levels in occipital lobe and cerebellum (Griffin et al., 1989, Marshak et al., 1992, Van Eldik and Griffin, 1994).