Plasma levels of hematological and inflammatory markers and more than 130 metabolites were investigated by magnetic bead panel multiplex assay and mass spectrometry assay, in addition to brain and plasma levels of brain-derived neurotrophic factor (BDNF), a neurotrophin involved in neuroplasticity and synaptogenesis, and indoleamine 2,3-dioxygenase, an enzyme whose dysregulated activity in humans has been correlated with mood disorders. The gene discussed is BDNF; the disease is mood disorder.