Psychopathology and 5-hydroxyindoleacetic acid excretion.

CONSIDERABLE indirect evidence, associating serotonin with central nervous system function and the actions of important psychotropic drugs, led to suggestions192 of a relationship between serotonin metabolism and schizophrenia. Despite considerable effort, experimental support for this suggestion has been inconclusive. Among studies in this area are those on quantitative excretion, and variability of excretion, of serotonin’s major metabolite, 5hydroxyindoleacetic acid, by various diagnostic populations, and on the relationship between such excretion and clinical symptomatology. Thus, schizophrenics have been reported variously to excrete supernormal,a-5 subnormal,6 and normal”3 amounts of this metabolite, and to show excessive variability in excretion. More recently a direct relationship between urinary levels of 5-hydroxyindoleacetic acid and other tryptophan metabolites and clinical symptomatology has been reported.rs-1s As part of a larger multidisciplinary study on the attributes of schizophrenia,? it was possible to examine some of these reports on a large population maintained under controlled conditions.ls~sO The present paper deals with a comparison of the quantitative excretion of 5-hydroxyindoleacetic acid by various diagnostic populations, and an analysis of the correlations between such excretion and pertinent biological and behavioral variables.