Abstract

Background: There is evidence that homocysteine contributes to various neurodegenerative disorders, and elevated plasma homocysteine levels have been observed in patients with multiple sclerosis (MS).

Objective: To investigate if and why plasma homocysteine levels are increased in MS, and whether they play a role in the disease course.

Methods: We compared plasma levels of homocysteine in 88 patients with MS and 57 healthy controls. In the MS group, 28 had a benign course, 37 were secondary progressive, and 23 primary progressive. To explore the underlying mechanisms, we measured serum levels of vitamins B₆ and B₁₂, folate, interleukin (IL)-12, tumour necrosis factor (TNF)-α, leukocyte nitric oxide production, and plasma diene conjugate levels (measure of oxidative stress).

Results: Mean (SD) plasma homocysteine concentration was higher in patients (13.8 (4.9) µmol/l) than in controls (10.1 (2.5) µmol/l; p<0.0001). However, there were no significant differences in homocysteine levels between the three clinical subgroups of MS. Serum concentrations of vitamin B₆, vitamin B₁₂, and folate were not different between patients with MS and controls. In the MS group, there were no correlations between plasma homocysteine levels and the serum concentrations of IL-12 or TNF-α, leukocyte nitric oxide production, or plasma diene conjugate levels.

Conclusions: Elevated plasma homocysteine occurs in both benign and progressive disease courses of MS, and seems unrelated to immune activation, oxidative stress, or a deficiency in vitamin B₆, vitamin B₁₂, or folate.