Robert Schwarcz and his associates found that the activity of KMO and 3-hydroxyanthranilic acid dioxygenase (3-HAO, the enzyme that transforms 3-HANA into QUINA) was reduced in the prefrontal cortex (Brodmann areas 9 and 10) of individuals affected by schizophrenia, whereas activities of kynureninase, kynurenine aminotransferase II, and quinolinic acid phosphoribosyltransferase were unchanged. Here, HAAO is linked to schizophrenia.