GFAP and psychiatric disorder: However, while increased S100B levels in patients with SCZ have been interpreted as a marker of structural damage or, alternatively, as a sign of astroglial dysfunction (Wiesmann et al., 1999; Rothermundt et al., 2001), the role of GFAP (a classical marker of astrogliosis) in psychiatric disease remains controversial (Samuelsson et al., 2006; Hao et al., 2010).