Introduction: Previous studies have suggested a considerable increase in plasma homocysteine (Hcy) levels in levodopa-treated Parkinson’s disease (PD) patients, and b12 and folate supplementation may decrease Hcy levels. However, the outcomes of catechol-O-methyltransferase inhibitors on levodopa-caused increase in Hcy levels were conflicting. The objective of these studies would have been to evaluate whether Hcy levels are elevated in levodopa-treated PD patients also to measure the outcomes of b12 and folate or entacapone on Hcy levels in levodopa-treated PD patients.

Methods: We examined and compared plasma Hcy levels in 20 levodopa-na?ve PD patients and 42 levodopa-treated PD patients, adopted by randomized assignment of 42 levodopa-treated patients to treatment groups with either b12 and folate, entacapone, or no medication.

Results: Plasma Hcy levels in levodopa-treated PD patients were more than individuals inside the control group, nevertheless the difference wasn’t record significant (15.25 ± 6.70 and 13.13 ± 4.68, P = .216). Patients given b12 and folate stood a significant decrease in plasma Hcy levels (P < 0.001). In the entacapone group, Hcy levels were mildly decreased, but the change did not reach statistical significance.

Conclusion: Levodopa-treated PD patients had higher plasma Hcy than levodopa-naive PD patients. Unlike entacapone, combination supplementation with vitamin B12 and folate was associated with significantly decreased plasma Hcy. We suggest that plasma Hcy levels should be monitored during levodopa treatment, and supplementation with inexpensive vitamin B12 and folate is beneficial for levodopa-treated patients.