MRI scans of 200 volunteers with mild cognitive impairment over 2 years, while they took high doses of B12, B6 and folic acid, were compared to those who took a placebo. B vitamins are known to reduce homocysteine, which is a risk factor for Alzheimer’s. For those with high homocysteine, the atrophy level in certain brain regions was 7 times greater in the placebo group. Those on B vitamins also had better cognitive function.