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Monday, March 21, 2011

B vitamins and Brain Shrinkage

Did you realize that after age 70, the average person’s brain shrinks more than 1% a year? At this rate, serious mental deterioration can become evident by age 80. Scientists have few clues about why this shrinkage occurs, nor why it is less in some Seniors than in others.

One of the few leads involve B vitamins. Certain B vitamins can reduce brain shrinkage and memory loss in people over 70, according to a randomized, double-blind clinical trial study in Britain of the effect of the B vitamins folic acid, B6 and B12.

All 168 volunteer participants were over age 70 and all had mild memory problems. Half of the subjects received daily a placebo, and the other half got a tablet containing 0.8 mg folic acid, 20 mg pyridoxine HCl (B6), and 0.5 mg cyanocobalamin (B12).

Brain shrinkage was measured by MRI scans. The mean rate of brain atrophy per year was 0.76%  in the active treatment group and 1.08% in the control subjects who took placebo pills 

The investigators also measured mental function, and the highest test scores occurred in the subjects that had the least brain shrinkage.

The mechanism of the beneficial effect is not known, but these vitamins are known to reduce blood levels of homocysteine, which has been correlated with the incidence of Alzheimer’s disease. Of course, that is not proof that homocysteine causes the disease or that these vitamins will help prevent it. Homocysteine is an amino acid, but is not found in food. It is a metabolite of the amino acid, methionine, which does occur in food.  We do know that deficiency of folic acid, B6, an B12 causes increase in homocysteine, so it is possible that older people are deficient in these vitamins. But while we await further research, it seems prudent for Seniors to  take these B vitamins daily.

Smith, A. D. et al. 2010. Homocysteine-lowering by B vitamins slows the rate of accelerated brain atrophy in mild cognitive impairment: a randomized controlled trial. PLoSOne.  5(9): e12244. doi:10.1371/journal.pone.0012244.