By Steven Reinberg
TUESDAY, Oct. 14 (HealthDay News) -- Vitamin B supplements don't slow cognitive decline in patients with mild to moderate Alzheimer's disease, a new study finds.
The theory was that vitamin B might slow the progression of Alzheimer's symptoms because the nutrient lowers homocysteine levels, which are elevated in people with the disease. Homocysteine is an amino acid produced by the body and has also been linked to an increased risk of heart disease.
"The results of the study indicate that we were successful in lowering homocysteine levels, but this did not translate into cognitive or clinical benefits," said lead researcher Dr. Paul S. Aisen, a professor at the University of California, San Diego, Department of Neurosciences. "The disappointing conclusion is that high-dose B vitamin treatment is not helpful in Alzheimer's disease."
Aisen thinks this study clearly demonstrates that people should not be taking vitamin B thinking it will combat the disease.
"This treatment is not useful and should not be recommended," Aisen said. "Because Alzheimer's disease is one of the major health-care problems in this country and worldwide, and because our current treatments are not adequately effective, many people are seeking alternatives, and one alternative has been to use vitamin therapy."
The findings were published in the Oct. 15 issue of the Journal of the American Medical Association.
For the study, Aisen's group randomly assigned 409 people with mild to moderate Alzheimer's disease to high doses of folate, vitamin B6 and B12 or a placebo. The researchers then measured the rate of cognitive decline using the Alzheimer's Disease Assessment Scale.
Over 18 months, they found that although vitamin B reduced homocysteine levels, there was no reduction in the rate of cognitive decline among patients taking the supplements. In fact, there was no significant difference in the scores on the Alzheimer's Disease Assessment Scale among those taking supplements and those receiving a placebo.
Interestingly, the people taking high-dose vitamin B supplements had more symptoms of depression than those taking a placebo, the researchers noted.
Dr. Sam Gandy, chairman emeritus of the Alzheimer's Association Medical and Scientific Advisory Council, said this study should put an end to the idea that lowering homocysteine levels helps Alzheimer's patients.
"Since cerebrovascular disease pathogenesis and that of Alzheimer's disease bear some relationship to each other, the hypothesis was put forward that if people were given B vitamin supplements to control their blood homocysteine, then this might lower the incidence of both stroke and Alzheimer's disease," he said. "Sadly, for the latter at least, the hypothesis has been rejected: Even among those with elevated homocysteine levels that were normalized with B vitamins, there was no obvious benefit in terms of lowering the risk for Alzheimer disease."
Greg Cole, a professor of medicine and neurology at the University of California, Los Angeles, thinks that once Alzheimer's is diagnosed, treating risk factors may not help in slowing the disease's progression.
"Like similar studies with antioxidants, anti-inflammatory drugs and estrogen, this study suggests that treating the risk factors for Alzheimer's after the patients have established disease is not useful and may even be harmful," he said.
Pamela Mason, a spokeswoman for the Health Supplements Information Service, cautioned that vitamin B is a dietary supplement, not a drug, and shouldn't be expected to perform like a drug.
"This is yet another study attempting to use high-dose vitamin supplements like drugs in the treatment and prevention of disease," Mason said in a news release. "B vitamin supplements are not intended to be taken like drugs to prevent or treat Alzheimer's disease. People should not be taking them for this purpose. They are health supplements, and their role is in helping to maintain good health, particularly in those large numbers of adults whose dietary intake is low. This study, like many other recent studies evaluating vitamins, does not address the issue of health maintenance."