Cerebrospinal fluid homovanillic acid is reduced in untreated Huntington's disease.

We measured homovanillic acid (HVA), 5-hydroxy indole acetic acid (5-HIAA), and tryptophan (TP) in cerebrospinal fluid (CSF) of 20 neuroleptic-free patients with Huntington's disease (HD), and compared mean values with those from four control groups including 15 normal individuals, 38 patients with dystonia, 23 untreated patients with Parkinson's disease, and 61 patients with other neurological diseases (ONDs). The mean levels of HVA in the CSF of patients with HD were reduced compared with those from normal controls (p < 0.001), dystonic patients (p < 0.005), individuals with ONDs (p < 0.0001), and even from untreated parkinsonian patients (p < 0.05). 5-HIAA and TP levels in the CSF of patients with HD were not significantly different from those in the CSF of control patients. Our data suggest a reduced dopamine neurotransmission in HD and may account for the bradykinesia observed in our patients.