Scientists have claimed a significant breakthrough in the search for possible drugs to prevent Alzheimer’s, after discovering a naturally-occurring molecule that blocks a key step in the development of the disease.

An international team of researchers including experts from the University of Cambridge struck upon the molecule after extensive investigations into the chain of events inside the brain, which lead to Alzheimer’s.

Discovering molecules that offer protection is hugely important, because they can offer clues to what substances could eventually be harnessed in drug treatments.

The molecule, called brichos, interrupts the process whereby malfunctioning proteins in the brain form into toxic clusters – a key link in the chain of molecular events that scientists now think leads to Alzheimer’s.

It works by sticking to threads of proteins – known as amyloid fibrils – and preventing them coming into contact with other proteins and forming clusters.

Ordinarily in the development of Alzheimer’s, the formation these of clusters, known as oligomers, sets of a chain reaction and they spread throughout the brain. Brichos – a kind of molecule known as a "molecular chaperone", which exists naturally in the body, can bind to the surface of amyloid fibrils and prevents them assisting other proteins from binding into clusters.

The image depicts a molecular chaperone binding to thread-fibrils, which can break a chain of events that scientists believe leads to Alzheimer's disease (PA)

Dr Samuel Cohen, research fellow at St John’s College, Cambridge, a lead author of the study, said it was the first to show that one of the “critical processes” in the development of Alzheimer’s disease could be inhibited.

“A good tactic now is to search for other molecules that have this same highly targeted effect and to see if these can be used as the starting point for developing a future therapy,” he said.

The study is published in the journal Nature Structural & Molecular Biology.