B vitamins fail in U.S. Alzheimer's disease study
WASHINGTON (Reuters) - High doses of B vitamins failed to slow cognitive decline in people with Alzheimer's disease, dashing the hopes for a new weapon against the fatal, mind-robbing ailment, U.S. researchers said on Tuesday.
Experts had viewed B vitamins as a potential way to lower the risk of Alzheimer's disease or slow its progression because the vitamins can cut the amount of the amino acid homocysteine, found in high levels in the blood of Alzheimer's patients.
But when the researchers gave people with mild to moderate Alzheimer's disease high-dose supplements of vitamins B6 and B12 and the B vitamin folic acid for 18 months, they did no better on tests assessing cognitive skills such as memory and language than similar patients who were given a placebo.
And the people who got the vitamin supplements unexpectedly experienced greater amounts of depression, the researchers wrote in the Journal of the American Medical Association.
"Our results give a very clear answer that these vitamins should not be taken to treat Alzheimer's disease. They're ineffective," said Dr. Paul Aisen of the University of California San Diego, who led the study.
Alzheimer's is an incurable brain disease that worsens over time. It is the most common form of dementia in the elderly.
"Alzheimer's disease breeds a great deal of desperation. So people will go to the health food store and look on the shelf that says 'brain health' and take one of everything," said Bill Thies, vice president for medical and scientific relations at the Alzheimer's Association advocacy group.
"These B vitamins are included in there. But this data really suggests that they're probably not getting any benefit. It is apparently a waste of money," Thies said.
The study involved 409 people with Alzheimer's disease at 40 sites throughout the United States. Some got daily doses of five milligrams of folic acid, one milligram of vitamin B12 and 25 milligrams of vitamin B6. The rest got daily placebo pills.
Those doses are far above the recommended daily allowance.
The people who took the B vitamins saw their homocysteine levels decline, but that did not translate into any benefits in terms of cognitive abilities compared to the placebo group.
Dr. Lon Schneider of the Keck School of Medicine of the University of Southern California, another of the researchers, said the study did not look at whether lowering homocysteine much earlier in life would prevent or delay Alzheimer's.
Amyloid beta protein is toxic to brain cells and plays an important role in the disease. The researchers had hoped by reducing homocysteine, it could reduce the toxicity of amyloid beta protein, Schneider said.
People can get folic acid and other B vitamins in the diet through leafy green vegetables and fortified cereals or through vitamin supplements.
The study was part of an initiative funded by the U.S. National Institutes of Health testing promising ideas for Alzheimer's treatment not being pursued by drug companies.
"This is closing down one strategy, but we fortunately have many others," Aisen said.
(Editing by Julie Steenhuysen)
