To the Editor: The randomized controlled trial by Dr Aisen and colleagues1 provided evidence that treatment with high-dose B vitamin supplements for 18 months does not slow cognitive decline in individuals with mild to moderate Alzheimer disease (AD). The rationale behind the study was that hyperhomocysteinemia (levels of homocysteine >15 μmol/L) is associated with a higher risk of dementia and AD2,3 and that homocysteine levels can be reduced by use of high-dose B vitamins and folate. Thus, the study was designed to determine in patients with AD whether a regimen of high-dose B vitamins and folate would slow their cognitive decline by reducing homocysteine levels. However, despite a 20% to 25% reduction in homocysteine level and an increase in B vitamin and folate levels associated with the active treatment, the trial found no effect.
Pratico D. High-Dose B Vitamin Supplements and Alzheimer Disease. JAMA. 2009;301(10):1020-1022. doi:10.1001/jama.2009.211