Cerebrospinal fluid indoleacetic acid in autistic subjects.

Cerebrospinal fluid (CSF) levels of the tryptamine metabolite, indoleacetic acid (IAA), have been measured in groups of autistic and control subjects. No significant difference was seen in group mean (+/- SEM) levels of CSF IAA (autistics 5.53 +/- 0.47 ng/ml, N = 10). The finding indicates that central metabolism of the behaviorally active trace amine tryptamine is probably normal in autism.