Brain atrophy is associated with Alzheimer's disease and impaired cognitive function.

Although the study, published in the Sept. 8 issue of Neurology, can't confirm that lower levels of B12 actually cause brain atrophy, they do suggest that "we ought to be more aware of our B12 status, especially people who are vulnerable to B12 deficiency [elderly, vegetarians, pregnant and lactating women, infants], and take steps to maintain it by eating a balanced and varied diet," said study co-author Anna Vogiatzoglou, a registered dietician and doctoral candidate in the department of physiology, anatomy and genetics at the University of Oxford, in England.

"It's worth looking at B12 levels. It's a simple blood test," affirmed Dr. Shari Midoneck, an internist at the Iris Cantor Women's Health Center in New York City. "It doesn't hurt to take B12."

Good sources of the vitamin include meat, fish, milk and fortified cereals.

According to the study authors, vitamin B12 deficiency is a public health problem, especially among older people. This study involved 107 volunteers aged 61 to 87 who were cognitively normal at the beginning of the study. All participants underwent annual clinical exams, MRI scans and cognitive tests and had blood samples taken.

Individuals with lower vitamin B12 levels at the start of the study had a greater decrease in brain volume. Those with the lowest B12 levels had a sixfold greater rate of brain volume loss compared with those who had the highest levels of the vitamin.

Interestingly, none of the participants were deficient in vitamin B12, they just had low levels within a normal range.

"They all had normal B12 levels, yet there was a difference between the higher levels and the lower levels in terms of brain shrinkage, which is new information which could potentially change what we recommend to people in terms of diet," said Dr. Jonathan Friedman, an associate professor of surgery and neuroscience and experimental therapeutics at Texas A&M Health Science Center College of Medicine and associate dean of the College of Medicine, Bryan-College Station campus.

Other risk factors for brain atrophy include high blood pressure, diabetes and high cholesterol.

Not only might B12 levels be a modifiable risk factor for cognitive decline, it might also be a clue to help clinicians assess cognitive problems earlier on.

Right now, it's not clear what the biological mechanisms behind the link might be, nor is it clear whether added B12 would avert brain atrophy.

"We are doing a clinical trial in Oxford in which we are giving B vitamins [including B12] to elderly people with memory impairment," Vogiatzoglou said. "In this trial, we are doing MRI scans at the start and the end, and so, we will be able to find out if taking B vitamins really does slow down the shrinking of the brain. The trial will be completed in 2009."

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