272 elderly individuals with a mean age of 77 years who had mild cognitive impairment were randomly assigned to receive, in double-blind fashion, placebo or B vitamins (0.8 mg of folic acid, 0.5 mg of vitamin B12, and 20 mg of vitamin B6) daily for 2 years.
168 of them completed the trial. The mean rate of brain atrophy per year (as determined by MRI scans) was 29.6% lower in the active-treatment group than in the placebo group (0.76% vs, 1.08%; p = 0.001).
The treatment response was related to baseline homocysteine levels: the rate of atrophy in participants with a homocysteine level > 13 pmol/L (the highest quartile) was 53% lower in the active-treatment group than in the placebo group (p = 0.001).
In contrast, active treatment had no effect on those with a baseline homocysteine level <_ 9.5 pmol/L (the lowest quartile). A greater rate of atrophy was associated with lower final scores on tests of cognitive improvement.
11 May 2011