In a recent study the researchers state "Our results show that B-vitamin supplementation can slow the atrophy of specific brain regions that are a key component of the [Alzheimer's Disease] process and that are associated with cognitive decline," the study authors conclude that: "Further B-vitamin supplementation trials focusing on elderly subjects with high homocysteine levels are warranted to see if progression to dementia can be prevented."
In an initial, randomized controlled study on elderly subjects with increased dementia risk (mild cognitive impairment according to 2004 Petersen criteria), researchers showed that high-dose B-vitamin treatment (folic acid 0.8 mg, vitamin B6 20 mg, vitamin B12 0.5 mg) slowed shrinkage of the whole brain volume over 2 yr. Here, they go further by demonstrating that B-vitamin treatment reduces, by as much as seven fold, the cerebral atrophy in those gray matter (GM) regions specifically vulnerable to the AD process, including the medial temporal lobe. In the placebo group, higher homocysteine levels at baseline are associated with faster GM atrophy, but this deleterious effect is largely prevented by B-vitamin treatment. They also showed that the beneficial effect of B vitamins is confined to participants with high homocysteine (above the median, 11 µM) and that, in these participants, a causal Bayesian network analysis indicates the following chain of events: B vitamins lower homocysteine, which directly leads to a decrease in GM atrophy, thereby slowing cognitive decline. Our results show that B-vitamin supplementation can slow the atrophy of specific brain regions that are a key component of the AD process and that are associated with cognitive decline. Further B-vitamin supplementation trials focusing on elderly subjets with high homocysteine levels are warranted to see if progression to dementia can be prevented.
Dr. Gwenaelle Douaud, one of the researchers states,”What we have shown is that, in these elderly people at risk for dementia and with high levels of homocysteine, you can slow the grey matter loss in the areas of the brain that matter, and therefore slow their cognitive decline. However, we would need a larger and longer trial to determine the optimal threshold of homocysteine that would warrant vitamin B supplementation and, crucially, if this could therefore slow the progression of Alzheimer's."
Douaud G, Refsum H, de Jager CA, Jacoby R, E Nichols T, Smith SM, Smith AD. Preventing Alzheimer's disease-related gray matter atrophy by B-vitamin treatment. Proc Natl Acad Sci. 2013 Jun 4;110(23):9523-8.