S100B and psychiatric disorder: S100B, a protein mainly expressed and secreted by astrocytes in the CNS, has been proposed as a marker of brain damage (Marchi et al., 2004; Gonçalves et al., 2008; Koh and Lee, 2014) and several studies have suggested that S100B is altered in neurological and psychiatric disorders (Ashraf et al., 1999; Lara et al., 2001; Steiner et al., 2011).