A new study suggests high doses of B vitamins may halve the rate of brain shrinkage in older people experiencing some of the warning signs of Alzheimer's disease.
Brain shrinkage is one of the symptoms of mild cognitive impairment, which often leads to dementia.
Researchers say this could be the first step towards finding a way to delay the onset of Alzheimer's.
Experts said the findings were important but more research was needed.
The study, published in the journal Public Library of Science One, looked at 168 elderly people experiencing levels of mental decline known as mild cognitive impairment.
This condition, marked by mild memory lapses and language problems, is beyond what can be explained by normal ageing and can be a precursor to Alzheimer's and other forms of dementia.
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Half of the volunteers were given a daily tablet containing levels of the B vitamins folate, B6 and B12 well above the recommended daily amount. The other half were given a placebo.
After two years, the rate at which their brains had shrunk was measured.
The average brain shrinks at a rate of 0.5% a year after the age of 60. The brains of those with mild cognitive impairment shrink twice as fast. Alzheimer's patients have brain shrinkage of 2.5% a year.
The team, from the Oxford Project to investigate Memory and Ageing (Optima), found that on average, in those taking vitamin supplements, brain shrinkage slowed by 30%.
In some cases it slowed by more than 50%, making their brain atrophy no worse than that of people without cognitive impairment.
'Protecting' the brain
Certain B vitamins - folic acid, vitamin B6 and B12 - control levels of a substance known as homocysteine in the blood. High levels of homocysteine are associated with faster brain shrinkage and Alzheimer's disease.
The study authors believe it was the B vitamins' effect on levels of homocysteine that helped slow the rate of brain shrinkage.
via BBC News - Vitamin B 'puts off Alzheimer's'.