S100B and major depressive disorder: It should be noted that altered levels of S100B have been found in other neuropsychiatric disorders such as schizophrenia, autism, and Alzheimer’s disease (Peskind et al., 2001; Al-Ayadhi and Mostafa, 2012; Aleksovska et al., 2014), implicating that alterations in levels of this molecule are not specific for major depression.