The effect of levodopa treatment on cerebral hemodynamics in patients with Parkinson's disease: serial transcranial Doppler studies

Abstract

Levodopa treatment in patients with Parkinson's disease (PD) is known to cause elevation in serum homocysteine levels. We investigated whether this increase in homocysteine level influences cerebral vascular flow velocity and resistance using transcranial Doppler (TCD). This study included 17 patients with de novo PD. Homocysteine levels and TCD parameters at middle cerebral artery were investigated before and after 3 months of levodopa treatment. Correlation analyses were done between changes in homocysteine levels and TCD parameters. After 3 months of levodopa treatment, homocysteine level increased significantly from 13.3mg/dL to 17.0 mg/dL (p < 0.001), but there were no meaningful changes in mean velocity (MV) and pulsatility index (PI). Correlation analysis revealed that the changes in homocysteine level had negative correlation with MV (r = -0.53, p = 0.027) and positive correlation with PI (r = 0.55, p = 0.028). Our study infer that although short-term treatment of levodopa itself does not cause overall alteration of cerebral blood flow velocities and resistances, patients who has greater degree of increased homocysteine level may still be at a risk of developing cerebral vascular stiffness