B Vitamins Fight Cognitive Decline

OXFORD, EnglandOlder adults with mild cognitive impairment (MCI) may benefit from a homocysteine-lowering therapy of B vitamins, suggests a new study (PLoS One. 2010;5(9):e12244. DOI: 10.1371/journal.pone.0012244). The Oxford Project to Investigate Memory and Aging (OPTIMA), coordinated out of the University of Oxford, noted the brain shows progressive atrophy with aging even in healthy adults, but to a greater degree in patients with MCI and conditions such as Alzheimers. As one such factor associated with faster rate of decline appears to be elevated concentrations of plasma total homocysteine (tHcy), researchers sought to determine whether an intervention with supplemental B vitamins could slow the rate of brain atrophy in subjects with MCI.

For the double blind, controlled trial (known as VITACOG), 271 subjects over 70 years old with MCI were randomized to receive either placebo or a combination of folic acid (0.8 mg/d), vitamin B12 (0.5 mg/d as cyanocobalamin) and vitamin B6 (20 mg/d as pyridoxine HcL) for 24 months. A subset of 187 individuals volunteered to have cranial MRI scans at the start and finish of the study. The main outcome measure was the change in rate of atrophy of the whole brain.

A total of 110 subjects in the active group and 113 in the placebo group completed the study; more than 78 percent of participants used at least 75 percent of their medication. In the active treatment group, geometric mean of plasma folate increased by nearly 270 percent and plasma vitamin B12 doubled; the placebo subjects saw increases of 3 percent and 10 percent respectively. Plasma tHcy decreased by 22.5 percent in the active group, but increased by 7.7 percent in the placebo group. In addition, 20.5 percent (17 out of 83) subjects in the placebo group had taken supplementary folic acid or vitamin B12. The mean rate of brain atrophy per year was 0.76 percent in the B vitamin group and 1.08 percent in the placebo group, with treatment response related to baseline homocysteine levels. The rate of atrophy in participants with homocysteine > 13 µmol/L was 53 percent lower in the active treatment group. Further, a greater rate of atrophy was associated with a lower final cognitive test score.

The researchers concluded the accelerated rate of brain atrophy in older adults with MCI can be slowed by intervention with B vitamins. They added 16 percent of adults over age 70 have MCI, and half of these develop Alzheimers disease, with adults with MCI who have accelerated brain atrophy more likely to develop Alzheimers disease. Therefore, they suggested further trials are needed to see if the B vitamin treatment could delay this progression.

Andrew Shao, Ph.D., senior vice president, scientific & regulatory affairs, Council for Responsible Nutrition (CRN), commented: The results from this small study have several important implications. The findings are consistent with other studies that have also suggested B vitamin status is inversely related to cognitive decline, particularly among those with mild impairment. This reinforces the notion that B vitamins exert a protective effect early in the process of cognitive decline, and are less likely to have a therapeutic effect, e.g., when full blown Alzheimers disease has occurred. The study also showed that the subjects whose baseline tHcy levels were highest, benefited the most; this supports the hypothesis that high Hcy levels have a detrimental effect on cognition. Because the study was small and not powered to assess cognitive decline, the results should be followed up with another larger-scale trial. Still, the results from this study show the potential for B vitamins to be used as a safe and affordable tool to help slow cognitive decline, and this is very encouraging.