Changes to proteins in blood and spinal fluid could help doctors predict the fate of Alzheimer's patients, research has shown.
As the severity of the disease increases, the molecules become longer, more rigid and more clustered, scientists have discovered.
Information about the proteins was combined with cognitive assessments to provide a new way of staging the illness and rating its progression.
"With a tool like this you may predict how fast this disease will go, and currently we can't do that - we just know everyone is different," said lead researcher Professor Mingjun Zhang, from Ohio State University.
"Looking at multiple indicators of the disease all at once increases the reliability of the diagnosis and prognosis."
Samples used in the study came from patients seen by co-author Professor Douglas Scharre.
"It was fairly easy to see changes between normal ageing and different stages of Alzheimer's disease using these biomarkers, and to see significant changes," Prof Scharre said.
A simple and accurate method of tracking Alzheimer's progression could speed up the development of new, effective and personalised treatments.
Currently, available medicines only treat symptoms of the disease. A number of experimental disease-modifying drugs are thought to have failed in trials partly because they could not be given early enough.
"The goal is to have a sensitive test that could be applied at the early stages of Alzheimer's disease and would not be too expensive," said co-author Professor Jeff Kuret.