Early Alzheimer’s Disease Pathology Identified in Brain Tissue

A study conducted by researchers at the University of Aberdeen has found that two proteins associated with Alzheimer’s disease pathogenesis – tau and amyloid – are present in the brain at very early stages of the neurodegenerative disease. The study – published in the journal, Acta Neuropathologica – provides evidence that both proteins can be found in areas of the diseased brain involved in information processing and new memory formation.

While the research could be valuable in the development of new Alzheimer’s therapies, it could also help pathologists with post-mortem diagnosis of the disease. The research was funded by Alzheimer’s Research UK, and human brain samples were donated via the Brains for Dementia Research program to allow the researchers to study neural changes at early and advanced stages of the disease.

While previous research has implicated both tau and amyloid proteins in the development of Alzheimer’s disease, these studies suggested that the two proteins accumulate in distinct areas of the brain. The current study is quite possibly the first to find that these proteins can be found in the same region of the brain during the early stages of the disease process, suggesting that they may be more intimately linked to the pathology of Alzheimer’s.

“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,” said Dr. Bettina Platt, Professor at the School of Medicine, at the University of Aberdeen Institute of Medical Sciences, and one of the authors of the publication. “These two have never been brought together in human cases, and the relationship between them has not been clear. Our observations therefore consolidate conflicting evidence from other studies on the role of the proteins in the disease process and strongly support a notion of an early stage interaction between the two.”

In all, Platt and her colleagues studied lateral temporal lobe samples collected from 46 people with Alzheimer’s disease. The researchers found that the coincident emergence of amyloid and tau during early stages of Alzheimer’s disease was strongly correlated with measures of cognitive decline.

“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,” said Platt. “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.”

Alzheimer’s disease affects an estimated 46.8 million people worldwide, with this number expected to double in the next 20 years. Countries like India and China are facing the fastest growth in the elderly population, and the demand for new treatments is continuing to increase.

“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,” said Dr. David Koss, a Research Fellow at the University of Aberdeen, and one of the leaders of the current study. “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 programs.”