High doses of B vitamins can reduce shrinkage of the brain that is frequently a precursor of Alzheimer's disease, British researchers reported Wednesday. In the best circumstances, the supplements reduced shrinkage by as much as 50%, and researchers hope that this may mean that the vitamins can delay the onset of Alzheimer's. A longer trial is now being planned to determine if that is the case. The results are all the more remarkable because of the widely publicized failures of many experimental Alzheimer's treatments.
Dr. A. David Smith of the University of Oxford and his colleagues studied 168 volunteers with mild cognitive impairment, which is characterized by memory loss, language problems and other mental difficulties beyond those normally associated with aging. It generally does not significantly interfere with daily activities. An estimated 16% of people over the age of 70 have mild cognitive impairment, and about half of those proceed to Alzheimer's disease.
The rationale for the study was simple: High levels of the amino acid homocysteine in the blood are thought to be linked to the development of Alzheimer's. B vitamins are known to reduce homocysteine levels.
Smith's group gave half the patients daily doses of a Swedish vitamin called Triobe Plus and half of them a placebo. The product, which is dispensed only by prescription, contains 0.8 milligrams folic acid, 0.5 mg cyanocobalamin and 20 mg pyridoxine hydrochloride. That is about 300 times the recommended daily intake of vitamin B12, four times the recommended dose of folate and 15 times the recommended dose of vitamin B6. "This is a drug, not a vitamin intervention," said nutritionist Helga Refsum of the University of Oslo, a co-author.
The team also used magnetic resonance imaging to measure brain volume. Normally, the human brain shrinks by about half a percent per year. Smith and his colleagues reported in the online journal PLoS One that the brains of the patients receiving the placebo shrank by an average of about 1.08% per year, while the brains of those receiving the supplement shrank by an average of only 0.76%, a decrease of 30%. But in patients who had the highest levels of homocysteine in their blood at the beginning of the two-year study, the shrinkage was reduced by 53%. Although the study was not designed to monitor mental capacity, the patients receiving the supplements scored better on mental tests, the researchers said.
"This is a very dramatic and striking result. It's much more than we could have predicted," Smith said in a statement.
At a news conference, Smith warned consumers against taking the high doses on their own, even though the results were "immensely promising." But when asked whether he would take it if he were diagnosed with mild cognitive impairment, he replied: "Yes, no hesitation. I would take it."
-- Thomas H. Maugh II