<prompt> In depression, there is deficiency of5-HTAcetylcholineDopamineGABA  <response>: The Karolinska Institute in Sweden first noted that low concentrations of the serotonin metabolite 5-hydroxyindoleacetic acid 5-HIAA in the lumbar cerebrospinal fluid CSF were associated with suicidal behavior. CSF, neurochemical, and receptor studies suppo the hypothesis that reduced central serotonin is associated with suicide. Reference: Synopsis of Psychiatry, pages 766,767. 