Effects of oral cobalamin supplementation on cognitive function in elderly persons with vitamin B12 deficiency

Abstract

Vitamin B12 deficiency is common in elderly persons and may be associated with cognitive impairment. However, evidence from trials of the effects of cobalamin supplementation on cognitive function is limited and inconclusive. We conducted an open prospective study to investigate the effects of cobalamin replacement therapy on cognitive function of older people with cognitive impairment and cobalamin deficiency. Ten patients aged ≥ 75 years with cognitive impairment (MMSE score between 10 and 25) and cobalamin deficiency (≤ 0.16 μg/L) were recruited. They were treated by vitamin B12: 1000 μg daily for 6 days, then weekly for 3 months, then monthly for 3 months. Cognitive function was assessed before treatment, 3 and 6 months later by Mini mental state examination (MMSE), verbal fluency test and Frontal assessment battery (FAB). Mean cobalamin serum levels significantly increased from 0.12 ± 0.03 μg/L at baseline to 0.22 ± 0.15 μg/L after 6 months (p = 0.004). Patients showed a statistically non-significant improvement of their mean MMSE scores; 20.4 ± 2.9, 22.6 ± 3.5 (p = 0.06) and 21.9 ± 3.0 (p = 0.07), at baseline, 3 and 6 months after treatment, respectively. Similar improvement was found in their verbal fluency and FAB scores. In spite of the trial's small number of patients, we found a nearly significant improvement in MMSE scores after 3 and 6 months of oral cobalamin supplementation. Previous studies showed that cobalamin supplementation could improve cognitive function in patients having a symptomatic mild dementia for less than 2 years. Therefore, all patients with cognitive impairment should be systematically investigated for cobalamin deficiency.