High doses of three common vitamins - folic acid, B12 and B6 - may be able to slow the progression of Alzheimer's disease, if the early results of a pilot study are supported by further research.
The study, published in the March /April issue of the American Journal of Geriatric Psychiatry, found that high doses of the B vitamins reduced levels of the amino acid homocysteine, previously linked by many scientists to risk for Alzheimer's disease.
Researchers from Georgetown University Medical Center's Memory Disorders Program who published the preliminary results are also conducting a 40 centre therapeutic trial to provide further evidence of the connection.
"Individuals with Alzheimer's disease have higher levels of homocysteine than people of similar age who do not have the disease," said Dr Paul Aisen, leader of the study.
"In our vitamin pilot study we have demonstrated that we are able to reduce levels of homocysteine using a vitamin regimen that is both safe and inexpensive. Now we are conducting a therapeutic trial to determine whether use of the vitamins folic acid, B12 and B6 to lower homocysteine level has a favourable impact on the course of the disease," he said.
Dr Aisen said the pilot study was the first step in the development of a potentially important way of slowing the course of Alzheimer's disease. However he warned: "We are not suggesting that people go out and take high doses of these vitamins. There are possible downsides, including peripheral nerve damage."
He added that the multi-site trial would reveal whether high doses of the three vitamins could become an important therapy for the devastating disease.
Known as Vital (VITamins to Slow Alzheimer's Disease), the long-term study has just begun recruiting patients across the country. Four hundred individuals with mild to moderate Alzheimer's disease will be randomly assigned to receive vitamins or placebos. An assessment of their cognitive function - memory, thinking and language - will be made to determine the progress of their disease during the course of 18 months.
Some researchers have found that the same combination of vitamins can help prevent blocked arteries in patients with heart disease. However the connection between blood folate and heart disease remains under debate.