Narrator: This is Science Today. A protein which helps regulate human immune responses and wound repair, may be the key link between the genetic and environmental risk factors for developing Alzheimer's Disease. Dr. Lennart Mucke of the University of California, San Francisco, says high levels of transforming growth factor beta-1, or TGF, cause toxic protein deposits to form in the brain.
Mucke: When a TGF beta is expressed outside of the nervous system at abnormally high levels, it results in excessive scarring. We think that in the brain a similar process happens - there is abnormal deposition of proteins.
Narrator: One of these proteins is amyloid, which is not only found in those genetically at risk for Alzheimer's, but in those who have had a head injury.
Mucke: But of course, not everybody who injures their head develops Alzheimer's Disease, so there must be genetic risk factors which then the environmental stress brings out and we think that TGF could connect these two processes.
Narrator: For Science Today, I'm Larissa Branin.