Total plasma homocysteine (tHcy) may be a risk factor for vascular diseases and is associated with renal failure or deficiency of vitamin B12 or folate. Recently, elevated tHcy concentrations were observed in patients with Parkinson's disease (PD), particularly those under levodopa treatment. Our objective was to determine whether changes in tHcy are also found in patients with restless legs syndrome (RLS) in relation to levodopa treatment and whether folate and vitamins B6 and B12 play a role in RLS.
In a total of 228 subjects, tHcy and B vitamin status (vitamins B6 and B12, folate) were studied: 97 patients with idiopathic RLS (40 under levodopa therapy), 39 with PD (25 under levodopa therapy), and 92 healthy controls adjusted for age and gender.
No significant differences were observed in tHcy levels between RLS patients and controls or between the RLS groups without treatment or with levodopa or dopamine agonist treatment. Mean tHcy was significantly higher in PD patients (13.8 micromol/l) than in either RLS patients (11.7 micromol/l) or controls (11.0 micromol/l; p<0.001). There was an inverse association between tHcy and vitamin B12 in each group.
RLS and, in particular, levodopa treatment in RLS are not associated with hyperhomocysteinemia. Elevated tHcy could, however, be confirmed in PD patients.