Scientists researching Alzheimer's disease have for the first time determined the structure of molecules in the human brain.

Published in the journal Nature, the study describes how scientists used cryo-electron tomography with fluorescence microscopy to deeply study the brain of a donor suffering from Alzheimer's disease.

As a result, they obtained three-dimensional maps where they could observe proteins, the molecular building blocks of life that are a million times smaller than a grain of rice, inside the brain. The study looked at two proteins that cause dementia - β-amyloid, a protein that forms microscopic sticky plaques, and tau, another protein that in Alzheimer's disease forms abnormal filaments that grow inside cells and spread throughout the brain. This study revealed the molecular structure of tau protein in tissues, how amyloids are arranged, and new molecular structures associated with this pathology in the brain. Dementia is the leading cause of death in the UK and Alzheimer's disease is its most common form.

In Alzheimer's disease, both β-amyloid plaques and abnormal tau fibers are thought to disrupt cellular communication, leading to symptoms such as memory loss, confusion and cell death.

Over the past 70 years, several thousand scientists around the world have assembled an extensive catalog of molecular structures, each working with proteins in isolation in vitro. However, it has long been known that most functions in biology result from the interaction of many different proteins. This study is part of a new effort by structural biologists to study proteins directly in cells and tissues, in their natural environment, and how proteins work together and affect each other, especially in the disease-affected human orgnism.