CSF monamine metabolites in movement disorders and normal aging.

We measured four monoamine metabolite levels in CSF before and after probenecid administration to normal controls and to patients with Huntington's disease (HD), dystonia, and tardive dyskinesia. We identified differences only for the dopamine metabolite homovanillic acid (HVA), which showed increased baseline values and decreased turnover in normal aging, but decreased baseline values and normal turnover in HD. These results suggest that dopamine neurons are linked both to normal aging and to HD and that CSF HVA studies can distinguish differences in the functioning of dopamine neurons in normal aging and HD.