Alzheimer's disease is caused partly by the build-up of abnormal proteins in the brain. Scientists already know that one of these abnormal proteins, amyloid peptides also called beta amyloids, can be infectious.
It seems that Alzheimer’s disease is easier to catch than first thought, as the National Academy of Sciences reports. Neurologist Yvonne S. Eisele and her team of fellow scientists had already proved that mice could catch Alzheimer’s disease from each other; however this only happened when the brain of a healthy mouse was injected with amyloid peptides from mice that already had Alzheimer's disease symptoms. Now a new study shows that injecting mice with the amyloid peptides anywhere on their bodies may cause the result in the development of Alzheimer's disease as well. Amyloid peptides are folded proteins that are useless substances, which healthy brains can clear away and reabsorb back into the body. However when a subject has Alzheimer's disease, the amyloid peptides are not cleared away. Eventually they harden into plaques. What Eisele's new research shows is that even if these amyloid peptides enter the mouse’s body through the leg or another part of its body, they can make their way to the brain of this mouse potentially causing Alzheimer's disease. The study goes on to say that when the researchers injected amyloid peptides also called beta-amyloid, from brain extract of infected mice into the bodies of mice, the injected animals developed symptoms of Alzheimer's disease after several months. While it remains unclear how the injected beta-amyloid caused disease, the authors believe that mechanisms exist allowing for the transport of beta-amyloid from peripheral tissues to the brain. This does not mean you can "catch" Alzheimer's disease from a person with Alzheimer’s disease by brushing against them, or by touching them when you have a cut on your arm. A person would have to be injected with infected gray matter from an Alzheimer’s patient’s brain. While no one would intentionally do this, the results raise the suspicion that beta amyloid proteins could be building up in areas other than the brain. Eventually these amyloid peptides make their way into the brain potentially causing Alzheimer’s disease. This information will help researchers unravel the mystery of how Alzheimer's disease develops.
Read more: Is Alzheimer's Disease contagious?
emphasis added by karrie