A blood test to predict if someone will develop Alzheimer's within a year has been created, in a breakthrough that raises hopes that the disease could become preventable.
After a decade of research, scientists at Oxford University and King's College London are confident they have found 10 proteins which show the disease is imminent. Clinical trials will start on people who have not yet developed Alzheimer's to find out which drugs halt its onset.
The blood test was described as a "major step forward" by Jeremy Hunt, the British Health Secretary, and charities which say it could revolutionise research into a cure.
Clinical trials into so-called "wonder drugs" have shown little improvement for sufferers, and scientists believe that by the time Alzheimer's is diagnosed, an irreversible "cascade" of symptoms has already occurred.
The new test can predict with 87 per cent accuracy whether someone suffering memory problems will develop Alzheimer's within a year.
The first tests are likely to be available in between two and five years. However, the study is likely to throw up ethical dilemmas about whether patients should receive potentially devastating news about their future. Simon Lovestone, professor of translational neuroscience at Oxford, said it was unlikely that GPs would use the test until treatment was available.
Eric Karran, director of research at Alzheimer's Research UK, which helped fund the research, said it brought the prospect of Alzheimer's becoming a preventable disease "significantly closer".
The study was published in the journal Alzheimer's & Dementia.