Leading article: Memory remade

Alzheimer's disease is not only a particularly distressing illness for those who suffer from it and for their families, it is a condition that has proved stubbornly resistant to treatment. Some new drugs can ameliorate the symptoms temporarily, while others may help to slow deterioration. While significant advances have been made in many other branches of medicine, however, any breakthrough in tackling Alzheimer's has been elusive.

Now, though, there may be light on the horizon. The surgical technique of brain stimulation, already used successfully to treat some types of Parkinson's disease, has been found to bring about a dramatic improvement in memory. The discovery, as so often in scientific advances, was made by accident. Doctors were trying to treat an obese man by identifying and adjusting a part of the brain that controls appetite. They failed; but they succeeded in stimulating his memory instead.

Further work has shown that not only long-term memory can be stimulated, but aspects of the ability to learn and retain information. The implications for Alzheimer's patients could be revolutionary.

One of the most positive features of deep brain stimulation is that, unlike much long-term drug treatment, it is non-addictive and can be reversed if it does not work. And while the procedure is expensive and bound to be more risky in elderly patients, it could save huge sums of money in the longer term, not least for medicine and 24-hour care.

If there is a real prospect that the destructive effects of Alzheimer's might one day be treated successfully, the future of Europe, with its ageing population, would suddenly look a great deal more hopeful.