- guardian.co.uk, Thursday June 7 2001 09.54 BST
The experiments, intended to ensure the safety of the treatment, are in their early stages and it could be more than five years before any successful treatments become widely available.
The four centres conducting the trials are being kept secret to prevent excessive demand from sufferers and their families, some of whom have travelled to Elan Pharmaceuticals headquarters in Stevenage, Hertfordshire, begging to be allowed to try its vaccine.
Richard Harvey, research director of the Alzheimer's Society, said: "People are desperate for a really effective treatment unlike the present drugs which are temporarily effective. But you have to go through the clinical trials process.
"We are hoping to hear later in the summer whether the vaccinations are generating the antibodies we need in order to get a therapeutic response."
Trials in the US have indicated patients get no side effects from a single dose. The British volunteers, most in the moderate stages of the disease, have been injected four times, once at the start, again after a month, a third time at three months and for a fourth at six months.
Now they are being monitored for an immunological response which can prevent the build-up of amyloid plagues, clumps of a protein closely associated with the disease.
Later, larger trials will involve patients at an earlier stage of the disease, but there is cautious optimism that the treatment will both slow the disease and may eventually prevent at risk patients developing it at all.
Stephen Donoghue, Elan's director of clinical affairs in Europe, said: "Reversing Alzheimer's is very difficult. We don't know if there is potential for a good treatment."
Research scientists and the drug industry have grown far more upbeat recently about tackling Alzheimer's. Although most sufferers are elderly, about 5% develop the disease between the ages of 30 and 40, which usually starts with memory loss and disorientation and can lead to severe depression or inappropriate behaviour.
Three drugs which can improve the quality of life for sufferers and delay progression have recently been approved for prescription under the NHS but several other drug trials are under way to develop medicines which can stimulate nerve cells into releasing more of a vital chemical messenger in the brain, or which could stimulate the survival or regeneration of nerve cells.
A report published by the Association of the British Pharmaceutical Industry suggested the cost of Alzheimer's to the UK was £5.5bn a year.
