It may be possible to transmit Alzheimer's disease from one person to another, according to a study published Wednesday in Nature. But this would occur only in highly unusual circumstances involving direct exposure to brain tissue, scientists say.

"This relates to a very special situation where people have been injected with, essentially, extracts of human [brain] tissue," said John Collinge, head of the Department of Neurodegenerative Disease at University College London, during a press conference about the study. "You can't catch Alzheimer's disease by taking care of someone with Alzheimer's disease."

The study involved autopsies of eight people who had received injections of human growth hormone as children more than 30 years ago. The growth hormone, extracted from human pituitary glands, had been tainted with a protein that caused these people to develop a fatal brain disease called Creutzfeldt-Jakob disease.

Researchers performed the autopsies to see if there was anything else unusual about the brains of these individuals. "And what we found, very much to our surprise, is that four of them had really quite significant deposition of Alzheimer amyloid protein in their brains," Collinge said. - Read More at NPR

Treatment From Brain Tissue May Have Spread Alzheimer's Protein