This has obvious implications for developing a similar blood test...in humans

Associate Professor David Holtzman

Instead of simply measuring blood amyloid levels, the researchers first injected their mice with a chemical called m266 - which appears to be able to "draw out" amyloid protein from the brain and surrounding areas.

Afterwards, within a few minutes, blood levels of the protein appeared to correlate accurately to the level of plaques formed in the brains of the mice.

Associate Professor David Holtzman, one of the research team, said: "This has obvious implications for developing a similar blood test for brain amyloid load in humans.

"Though we will not be able to detect risk in someone who has not begun to accumulate amyloid, we hope to predict the disease well before the symptoms appear.

"Such a test could distinguish individuals suffering from dementia caused by Alzheimer's from those with other types of dementia, and may help us evaluate an individual's response to particular medical therapies."

Planning ahead

Dr Simon Lovestone, from the Institute of Psychiatry at King's College London, said that even if treatments for Alzheimer's were not available, being able to receive a quick diagnosis was important to patients.

He said: "One of the most important things is that they get an early diagnosis - they can start putting things in order and preparing for what lies ahead."

However, he said that although a treatment would not be available for at least 10 years, he was hopeful that trials of potential medication would be successful.