A study showing how rogue proteins clump together in the brain of Alzheimer's patients was welcomed by dementia experts.
US scientists found the proteins that cause devastating memory problems and confusion come in different strains - a discovery that could lead to earlier treatment.
Dr Carol Routledge, director of research at Alzheimer's Research UK, said: "Stopping or slowing the progression of Alzheimer's disease is critical and key to doing this is understanding how different forms of toxic proteins spread through the brain.
"The build-up of amyloid is one of the first changes in Alzheimer's, but why it happens and how it spreads is still not fully understood.
"The important tools developed in this study provide insight into different forms of amyloid in the brain, suggesting they could explain differences in symptoms between people with Alzheimer's.
"The work suggests that amyloid spreads through the brain in a similar way to the prion protein responsible the brain disease CJD; but more work is needed to confirm this.
"Although initial results in mice provide useful insights into the mechanisms of disease, they must be followed up with studies in people.
"Improving our ability to track different forms of amyloid will provide a greater understanding of Alzheimer's and with more development, could help to predict how a person's Alzheimer's may progress in future."
Dr Clare Walton, research manager at Alzheimer's Society, said: "This study focuses on amyloid, the protein which builds up in dense clumps in the brains of people with Alzheimer's disease."Amyloid can fold itself into either harmless or toxic shapes depending on several factors - including genetics and changes in how a brain cell handles the protein.
"In some configurations, amyloid can cause a domino effect, whereby other nearby proteins twist themselves into the same shape, potentially resulting in disease.
"Whether this domino effect could occur in Alzheimer's has been a topic of debate for some time, and this study further explores the issue using cutting edge technology.
"The researchers found that the shape of amyloid protein varied between genetic Alzheimer's, non-genetic Alzheimer's and cerebral amyloid angiopathy, a condition caused by amyloid build up in blood vessels of the brain.
"This suggests that the way amyloid folds itself could affect how diseases develop.
"Although this study won't immediately lead to a new treatment, it increases our understanding of amyloid in Alzheimer's disease and highlights the need for more research."
The study by Professor William DeGrado, of California University in San Francisco, and colleagues was published by the journal Proceedings of the National Academy of Sciences.