New research raises the scary prospect that Alzheimer's could be transmissible in a similar way to infectious prion diseases.
The brain damage seen with Alzheimer's may originate in a form similar to that of diseases such as bovine spongiform encephalopathy - mad cow disease - and Creutzfeldt-Jakob, says a team at the University of Texas Health Science Center in Houston.
""The underlying mechanism of Alzheimer's disease is very similar to the prion diseases," says neurology professor Claudio Soto.
"It involves a normal protein that becomes misshapen and is able to spread by transforming good proteins to bad ones. The bad proteins accumulate in the brain, forming plaque deposits that are believed to kill neuron cells in Alzheimer's."
Alzheimer's is a form of progressive dementia that affects memory, thinking and behavior. There are around 5.4 million affected individuals in the US, of whom 90 percent suffer from a sporadic form. It's the sixth leading cause of death in the country, according to the Alzheimer's Association.
The team injected the brain tissue of a confirmed Alzheimer's patient into mice, and compared the results to those from injected tissue of a control without the disease.
None of the mice injected with the control showed signs of Alzheimer's, whereas all of those injected with Alzheimer's brain extracts developed plaques and other brain alterations typical of the disease.
"The mouse developed Alzheimer's over time and it spread to other portions of the brain," says Soto.
"We are currently working on whether disease transmission can happen in real life under more natural routes of exposure."