Following the discovery of a protein called clusterin, a simple blood test could soon be developed to predict Alzheimer's disease up to ten years before the appearance of symptoms.
Scientists have suggested that levels of clusterin rise 'many years' before symptoms of Alzheimer's disease first appear.
An early test for the condition could allow those patients could have early treatment and make improvements to their lifestyle to minimise the impact of the disease.
Patient groups said the prospect of a blood test for Alzheimer's disease was the 'holy grail' for researchers in this area and the latest findings bring this a step closer.
The researchers compared blood samples taken from 300 people with either Alzheimer's disease, mild impairment or normal brain function.
It was found that clusterin levels were linked with Alzheimer's symptoms and higher levels indicated more rapid and severe memory loss and brain shrinkage as shown on brain scans.
Experiments with mice showed that the protein is produced in increasing amounts with age and is also linked to the development of plaques in the brain, which interfere with cell communications systems.
The clusterin surrounded the plaques.
It is not known if the plaques are the cause of Alzheimer's disease or a sign of it but this research has shown that the body produces greater quantities of clusterin along with the plaques and it may be an attempt to protect the brain from the build up of the plaques.
Thus high levels of clusterin, which can be detected in a blood sample, could be used as an early warning sign that the body is already fighting Alzheimer's disease.
In America, the researchers used 60 patients to find that clusterin levels can be used to predict Alzheimer's onset up to ten years before symptoms appear.
"We are very enthusiastic about these results because they identify a strong signal in blood from clusterin protein that appears to be relevant to both pathology and symptoms in patients with Alzheimer's disease, adding further evidence to the role of clusterin in Alzheimer's disease," the Telegraph quoted lead author Dr Madhav Thambisetty, formerly of the Institute of Psychiatry and now working in America, as saying.
"A primary goal in Alzheimer's research is to develop an inexpensive, easily administered test to accurately detect and track the progression of this devastating disease.
"Identifying clusterin as a blood biomarker that may be relevant to both the pathology and symptoms of the disease may bring us closer to this goal," he added.
The findings are published in the Archives of General Psychiatry.