S100B and schizophrenia: This amino acid may also directly or indirectly influence glial function and therefore levels of S100B, calcium-binding protein linked with glial pathology.<h4>Aim</h4>Investigating an association between initial S100B serum concentrations as a glial marker, its changes, and symptoms severity during use of sarcosine in patients with predominant negative symptoms and stable antipsychotic treatment.<h4>Methods</h4>Sixty subjects with a diagnosis of schizophrenia with predominant negative symptoms completed a 6-month randomized, double-blinded, placebo-controlled prospective study.