Attention has been focused recently on the association between
vitamin B12 metabolism and the pathogenesis of
multiple sclerosis (MS). Several recent reports have documented
vitamin B12 deficiency in patients with MS. The etiology of this deficiency in MS is unknown. The majority of these patients do not have
pernicious anemia and serum levels of the
vitamin are unrelated to the course or chronicity of the disease. Moreover,
vitamin B12 does not reverse the associated
macrocytic anemia nor are the neurological deficits of MS improved following supplementation with
vitamin B12. It has been suggested that
vitamin B12 deficiency may render the patient more vulnerable to the putative viral and/or immunologic mechanisms widely suspected in MS. In the present communication, we report that serum
vitamin B12 levels in MS patients are related to the age of onset of the disease. Specifically, we found in 45 MS patients that
vitamin B12 levels were significantly lower in those who experienced the onset of first neurological symptoms prior to age 18 years (N = 10) compared to patients in whom the disease first manifested after age 18 (N = 35). In contrast, serum
folate levels were unrelated to age of onset of the disease. As
vitamin B12 levels were statistically unrelated to chronicity of illness, these findings suggest a specific association between the timing of onset of first neurological symptoms of MS and
vitamin B12 metabolism. In addition, since
vitamin B12 is required for the formation of myelin and for immune mechanisms, we propose that its deficiency in MS is of critical pathogenetic significance.