Evidence that folic acid deficiency is a major determinant of hyperhomocysteinemia in Parkinson's disease.

In the present work we measured blood levels of total homocysteine ((t)Hcy), vitamin B(12) and folic acid in patients with Parkinson s disease (PD) and in age-matched controls and searched for possible associations between these levels with smoking, alcohol consumption, L-DOPA treatment and disease duration in PD patients. We initially observed that plasma (t)Hcy levels were increased by around 30 % in patients affected by PD compared to controls. Linear correlation, multiple regression and comparative analyses revealed that the major determinant of the increased plasma concentrations of (t)Hcy in PD patients was folic acid deficiency, whereas in controls (t)Hcy levels were mainly determined by plasma vitamin B(12) concentrations. We also observed that alcohol consumption, gender and L-DOPA treatment did not significantly alter plasma (t)Hcy, folic acid and vitamin B(12) levels in parkinsonians. Furthermore, disease duration was positively associated with (t)Hcy levels and smoking was linked with a deficit of folic acid in PD patients. Considering the potential synergistic deleterious effects of Hcy increase and folate deficiency on the central nervous system, we postulate that folic acid should be supplemented to patients affected by PD in order to normalize blood Hcy and folate levels, therefore potentially avoiding these risk factors for neurologic deterioration in this disorder.