Thirty patients with
Parkinson's disease, treated with
levodopa for the past few years, concomitantly received 500 mg of
cytidine diphosphate choline (
CDPC) daily for 30 days. Significant improvements in some of the
neurologic signs and in several electrophysiologic parameters measuring the
traction reflex and the active contraction were observed. A greater stability of therapeutic response between doses of
levodopa was also seen, although the incidence of
dyskinesia increased. In a second stage of
CDPC treatment, also lasting 30 days, the dose of
levodopa was reduced by one-third, and the incidence of
dyskinesia dropped to its previous level, but the therapeutic response remained stable. Addition of
CDPC produced significant increases in plasma concentrations of
dopa and
homovanillic acid, with no modifications in
tyrosine or
3-O-methyldopa concentrations. A significant increase in the number of lymphocytic dopaminergic receptors also occurred.