Ron Winslow in Wall St. Journal (WSJ), pg D3, on 2/19/09, reports that Genentech researchers propose a new theory about Alzheimer’s disease based on some early lab and mouse experiments. Further testing will need to be done to explore their theory that Alzheimer’s may be a natural process similar to one that occurs in the prenatal brain to prune excess nerve cells and fibers. Genentech hopes that further experiments will reveal what happens in the older adult brain to trigger this natural prenatal process. The current prevailing model of Alzheimer’s is that it is the buildup in the brain of beta amyloid plaques, a fragment of a larger protein called APP. Genentech’s research, as well as research done at the Salk Institute, shows that APP playes a naturally destructive process in prenatal development. Beta amyloid is not involved in the naturally occurring prenatal process but is involved in the onset of Alzheimer’s.
For some context: we have the most brain cells before birth and many are destroyed during development in the womb. Although the process is not clear, neighboring brain cells learn to “get along” with each other, to communicate with their neighbors, and the ones that don’t are destroyed.