Decoded: How Alzheimer's spreads

In a major breakthrough, a team of US researchers has confirmed that deposits of a protein called beta amyloid in the brain trigger Alzheimer's disease.

Using 3D lab culture, the team at the Massachusetts General Hospital also found an enzyme that plays a key role in the progression of the disease, Washington Post reported.

A 3D cell culture is an artificially-created environment in which biological cells are permitted to grow or interact with its surroundings in all three dimensions.

Scientists already know that two protein variants - amyloid beta that forms insoluble plaques and tau that creates neuro-fibrillary tangles - are distinguishing features of Alzheimer's disease.

"The question was, does the amyloid really cause the tangles because the tangles are what kill the nerve cells? And this is the first proof of concept in a human nerve cell system that it does," lead study author Rudolph Tanzi, director of the genetics and ageing research unit at the Massachusetts General Hospital, was quoted as saying.

To reach the conclusion, researchers used a 3D culture with neural stem cells that carried the variants in two genes, the amyloid beta precursor and presenilin 1, which is found in early onset Alzheimer's.

The 3D models in the lab created both plaques and tangles.

The discovery may revolutionise drug discovery for other neuro-degenerative disorders, researchers noted in a paper that appeared in the journal Nature.