Endothelial dysfunction and hyperhomocysteinemia in Parkinson's disease: Flow-mediated dilation study

Background: Levodopa (l-dopa) therapy in Parkinson's disease (PD) increases serum homocysteine levels because of its metabolism via catechol O-methyltransferase, which may lead to endothelial dysfunction. Method: We enrolled 40 PD patients treated with l-dopa, 33 PD patients treated with l-dopa/entacapone, 22 untreated PD and 30 controls, and compared the flow-mediated dilation in these subjects. Results: The flow-mediated dilation was significantly lower in PD patients with l-dopa (6.0±1.8%) than in those with l-dopa/entacapone (7.2±1.1%, P=0.03), untreated PD patients (7.8±1.2%, P<0.05), and controls (8.5±2.9%, P<0.05). The homocysteine level was significantly higher in PD patients with l-dopa than in other groups. In a multivariate logistic regression model, the uppermost homocysteine quartile was an independent predictor of the lowest tertile of flow-mediated dilation (odds ratio, 6.33; 95% confidence interval, 1.61-26.65; P=0.012). Conclusions: Our findings indicate that endothelial dysfunction may be associated with chronic l-dopa treatment in patients with PD.