Low vitamin B-12 status in confirmed Alzheimer's disease as revealed by serum holotranscobalamin.

Abstract

To examine the possible association of holotranscobalamin, the active fraction of serum cobalamin, with Alzheimer's disease. 51 patients with pathologically confirmed Alzheimer's disease and 65 cognitively screened elderly controls were studied. Serum holotranscobalamin was measured by a new solid phase radioimmunoassay. Geometric mean levels showed no significant case-control differences for serum total cobalamin, but lower levels of holotranscobalamin in Alzheimer's disease (41.1 pmol/l) than in controls (57.1 pmol/l) (p < 0.001). The odds ratio of Alzheimer's disease was significant for low holotranscobalamin but not for low total cobalamin. Disturbed cobalamin status is common in Alzheimer's disease and accordingly measurement of holotranscobalamin should be considered in the assessment of cognitively impaired patients.