Neurochemistry of dopamine in Huntington's dementia and normal aging.

We measured the dopamine metabolite homovanillic acid (HVA) in cerebrospinal fluid (CSF) before and after probenecid administration in normal controls and in patients with Huntington's disease. Baseline CSF HVA concentrations correlated positively with age in normal control subjects. Baseline CSF HVA concentrations were reduced in patients with Huntington's disease, and the degree of this reduction correlated with the severity of dementia and with the duration of disease. These results suggest that changes in the metabolism of dopamine by dopaminergic neurons may be associated with the dementia of Huntington's disease as well as with normal aging. These changes in dopaminergic functioning are apparently different in Huntington's disease than in normal aging and can be detected by measuring CSF HVA concentration.