Scientists have detected key changes in the brains of people who are showing the early signs of Alzheimer's, which they claim could improve diagnosis of the disease.

The study, carried out by researchers at the University of Aberdeen, found two molecules assumed to contribute to the disease are both present during the very early stages of Alzheimer's in an area of the brain involved with memory formation and information processing.

Funded by Alzheimer's Research UK, the study could have implications for the development of new drugs and also potentially provide important information for diagnosis of the disease, scientists said.

The team led by Dr David Koss and Professor Bettina Platt used human brain samples provided by the Brains for Dementia Research platform to investigate changes in the brain at different stages of Alzheimer's disease. Researchers developed ways to study two proteins, tau and amyloid, both associated with the disease, and tried to determine how they contributed to the onset, progression and symptoms of Alzheimer's.

Dr Koss said: "The entire research community is in agreement that it is a primary challenge to identify Alzheimer's disease early - and our findings will go some way to help achieve this, though ultimately it will be up to the scientific community to further evaluate and build upon these results.

"These early-stage changes in the brains of people with Alzheimer's disease highlight key biochemical processes that may not only enable improved diagnostic procedures but may also inform drug development programmes."

Ms Platt added: "In the field of Alzheimer's and dementia research there has been a long-running battle regarding the two main suspects that might cause brain cells to die - tau and amyloid.

"It has long been assumed that Alzheimer's-related changes within the brain occur long before symptoms are evident but, so far, reliable methods to detect these were elusive.

"However, we have managed to modify experimental procedures in a way that we can now very sensitively determine when and where these proteins appear, and the big surprise was that they both appear together very early on, and in the same brain area.

"In doing so, we have established a new benchmark for pathological investigations."