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Those at risk of developing Alzheimer’s disease may be able to slow its onset through daily B vitamins.

We already know that a high level of the amino acid homocysteine in the blood is a risk factor for Alzheimer’s and that B vitamin supplements help reduce homocysteine levels. But it was unclear whether these supplements could slow the progression of mild cognitive impairment (MCI) to Alzheimer’s.

David Smith and Gwenaelle Douaud at the University of Oxford led a research effort to find out. They used MRI to track changes in the brains of 200 elderly volunteers with MCI over two years. Half were given high doses of vitamin B12, B6 and folic acid; the rest took a placebo.

The team found that areas of the brain most seriously affected by Alzheimer’s, including the hippocampus and cerebellum, were protected in volunteers given the vitamins. For instance, in those with high homocysteine, the atrophy rate in these brain regions was seven times greater in the placebo group than in the vitamin group.

The reduction of atrophy seemed to translate into better brain function, too: Those volunteers given B vitamins performed better on cognitive tests (PNAS).

“It demonstrates for the very first time that it is possible to modify the disease process in Alzheimer’s,” says Smith.

Simon Ridley at Alzheimer’s Research UK warns that more work is needed to explore the link, but Smith points out that vitamin supplements are safe for most people and could perhaps be offered to people at high risk of Alzheimer’s as a precaution.

“I think we need to bite the bullet,” he says, “and ask, ‘Is there any reason that elderly people with memory problems shouldn’t be offered them in the meantime?’ ”