The prototype vaccine has proved effective at combating the disorder in mice suffering from the human form of the degenerative brain disease, which affects more than 400,000 people in Britain and is estimated to cost the country pounds 5.5bn a year.
The number of affected individuals is likely to rise by 50 per cent over the next 40 years because of the ageing population.
The vaccine works by stimulating the body's immune system to produce antibodies against the protein deposits, known as plaques, that build up in the brain of Alzheimer's patients.
The experiments, published in the journal Nature, showed that the vaccine was highly effective at preventing protein plaques appearing in the brains of susceptible mice inoculated at an early age.
A second experiment on older mice who had already developed signs of Alzheimer's disease demonstrated that the vaccine effectively prevented the disease from worsening.
Dr Dale Schenk, who led the research team from Elan Pharmaceuticals, a San Francisco drug company, said the results were far more clear-cut than he ever expected.
"It was a dramatic result. I've never seen anything like it. I would have been satisfied with a 20 or 30 per cent reduction in plaques but we actually got something like 90 per cent," he said.
Other scientists who have seen the work but have no connection with the company said the vaccine has the potential to become the first effective treatment for what is currently an incurable and degenerative condition.
Although the appearance of protein deposits in the brain is a distinguishing feature of Alzheimer's disease, scientists are unsure whether they cause dementia or are a by-product of nerve degeneration.
"If we can clear protein plaques in humans or mice, the next question is whether we can block the onset of dementia, and the death of nerve cells in the brain, which is what the disease is all about," said Peter St George-Hyslop, professor of medicine at the University of Toronto."We now have a treatment that essentially cures or prevents one aspect of the disease."
Elan Pharmaceuticals plans to apply for permission to begin human clinical trials before the end of the year but it will be many more years before a vaccine can be used routinely on patients, Dr Schenk said.
t IT REALLY may be possible to enhance your IQ through your diet - or, more worryingly, lower it. New research has identified a possible link between levels of brain chemicals and intelligence test results.
William Brooks, a neuroscience researcher at the University of New Mexico in Albuquerque, told New Scientist magazine the results showed it might be possible to improve intelligence with dietary supplements. The two chemicals are N-acetylaspartate (NAA) and choline. NAA is found only in neurons, while choline is found in nerve cell membranes.Reuse content