To the Editor: The randomized trial by Dr Aisen and colleagues1 evaluating the use of high-dose B vitamins in patients with AD suggested that there is no cognitive benefit from such a treatment approach. Although this study provides some assistance in selection of potential combination therapies, several questions arise.
Prior studies have shown a relationship between low cerebrospinal fluid folate levels in patients with AD compared with normal controls. Low levels of L-methyl folate and methyl B12 have correlated with increased risk of cognitive impairment.2 It is possible that the patients in the study by Aisen et al were too advanced beyond a potential time window for benefit from B vitamin intervention to see a beneficial result.
Machanic BI. High-Dose B Vitamin Supplements and Alzheimer Disease. JAMA. 2009;301(10):1020-1022. doi:10.1001/jama.2009.212