Biologically Active Vitamin B12, Homocysteine, and Alzheimer Disease

Studies of the associations among the components of the vitamin B12 cascade and dementia have had inconsistent results (Eur J Neurol 2009; 16:808, Am J Clin Nutr 2007; 85:511, and Neurology 2004; 62:1972). In this study, researchers examined three of the cascade components — homocysteine, holotranscobalamin (holoTC, the biologically active fraction of vitamin B12), and folate — and subsequent risk for Alzheimer disease (AD). Participants were 271 initially nondemented older adults (baseline age range, 65–79) selected from a larger cohort based on the availability of baseline serum samples of these components. After a mean follow-up of 7.4 years, participants underwent a multistep AD screening process.

In a multiple logistic regression model …