Alzheimer's disease may not be due to the build up of plaques in the brain but the poor clearance of them, according to new research.
Scientists from University of Medicine in St Louis measured the amount of beta-amyloid in the brain fluid of Alzheimer's patients and found that the clearance of the plaque was 30 per cent slower than in healthy individuals.
The researchers said that in future, the level of plaque could be measured by a blood test to detect onset of the form of dementia.
In addition, scientists will be able to study the process and hopefully develop a drug to target the process.
Professor Clive Ballard, the director of research at the Alzheimer's Society said that the study gives an important insight into the building blocks of Alzheimer's.
"The burning question is whether this process starts before the onset of symptoms as this could be vital to the development of new treatments. As the number of people with dementia reaches a million in just 15 years we urgently need more investment in research," he said.