Vitamin B 12 plasma concentrations in Alzheimer disease.

: In this contribution we investigated the correlation between plasma vitamin B12 levels and cognitive impairment in Alzheimer's disease. We could demonstrate a significant inverse correlation when the MMSE scores of those patients with the lowest 10% Vitamin B12 plasma levels (<184 ng/ml) were compared with the upper 10% Vitamin B12 plasma levels (>598 ng/ml): p=0.008, Spearman-Rho= -0.36. MMSE in the upper percentile of plasma B12 levels was 20.0 +/- 4.6 and in the lower percentile 15.7 +/- 6.1, resulting in a difference of 4.3 MMSE points. We conclude, that vitamin B12 deficiency could aggravate or accelerate the course of Alzheimer disease as vitamin B12 possesses neuroprotective and anti-inflammatory properties.