B vitamins slow brain changes in a subgroup of older people

Oxford researchers announce further results from 2010 clinical trial

Posted on 20th May 2013

Dementia researchers at the University of Oxford have released additional data from a clinical trial carried out in 2010, which suggested that high dose B vitamins could halve brain shrinkage in older people with memory problems. The new findings delve deeper into the data, linking B vitamin supplementation to slower rates of shrinkage specifically in areas of the brain affected in Alzheimer’s disease in people with high levels of homocysteine. The results are part-funded by Alzheimer’s Research UK and published online in the journal Proceedings of the National Academy of Sciences, USA.

The trial, called VITACOG, studied the effect of high doses of folic acid, vitamin B6 and vitamin B12 on brain shrinkage in 168 volunteers with mild memory problems (mild cognitive impairment). The two year study found that rates of total brain shrinkage were slower in those taking high dose B vitamin supplements, although this was most marked in people with poor vitamin status, i.e., those who started the study with high levels of the amino acid homocysteine in their blood.

Previous research has linked high levels of homocysteine to cognitive impairment and a greater risk of Alzheimer’s. Homocysteine levels rise with age, and intake of folic acid, vitamin B6 and vitamin B12 can help to reduce these levels in the blood.

The team has now looked in greater detail at brain scans from 156 volunteers that took part in the VITACOG study – 76 given a placebo and 80 receiving high dose B vitamins. Rather than focusing on total brain shrinkage, as reported in 2010, they now looked at shrinkage in different regions of the brain.

Of the 156 volunteers that took part in the study, 77 had homocysteine levels greater than 11.06μmol/L. Compared to participants with lower levels, those with higher homocysteine had a faster rate of shrinkage specifically in the parts of the brain known to be affected in Alzheimer’s disease. B vitamin treatment slowed the shrinkage in these particular regions by almost 9-fold (from 5.2% to 0.6%) over the two-year period. In contrast, B vitamin treatment had no effect on participants with lower levels of homocysteine.

The researchers also found that shrinkage in these brain areas was associated with a poorer performance on some memory and thinking tests. Using a statistical network method, the authors propose that high doses of B vitamins (especially B12) can lower homocysteine levels, which then slow the rate of brain shrinkage, which could in turn slow cognitive decline. The authors conclude that B vitamin treatment can modify a key component of the disease process in Alzheimer’s in those with high homocysteine, but further trials are needed to confirm the findings.

Dr Eric Karran, Director of Research at Alzheimer’s Research UK, said:

“Very few clinical trials have looked at the effect of B vitamins on people with memory impairments and those that have report mixed results. The VITACOG study was one of the largest studies to look at B vitamins in people with memory problems and so it is good to see as much data being drawn from this study as possible.

“While the VITACOG trial showed that B vitamins slowed brain shrinkage in people with mild cognitive impairment and high homocysteine, it is too early to know whether these effects mean someone is less likely to develop dementia in the long term. It is also not clear from other research in this area whether B vitamins would have any benefit for those who already have dementia. Until further trials have confirmed these findings, we would recommend people think about eating a healthy and balanced diet. Controlling weight and blood pressure, as well as taking exercise, are also ways that we can help to keep our brains healthy as we get older.”

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