Does rodent brain study point to a candidate model for ’cause’ of Alzheimer’s disease? The derivative of amyloid-beta precursor protein (APP), which is linked to the “plaques” and “neurofibrillary tangles” that are characteristic of the Alzheimer’s brain, is well on the way to meeting Koch’s postulates, the formal requirements that allow us to say that a substance has a causal role in a disease. First, it is found regularly in the brains of animals affected with a form of memory loss that is considered an animal model of Alzheimer’s. It is not found in the brains of unaffected animals. When extracted from affected brains and given to healthy animals, they develop signs of memory loss. And the same protein appears in human brains. The mild cognitive deficits which precede the development of fullblown Alzheimer’s dementia could be caused by this protein demonstrated to cause transient memory deficits in rodents. It might be the first step in the cascade of changes to brain proteins that underlie the degenerative process in Alzheimer’s. If this finding is borne out, it holds out the promise of early detection of the Alzheimer’s disease process before dramatic cognitive deficits develop. Identification of the protein could also lead to the development of medications which block its actions or vaccines to immunize patients against the development of Alzheimer’s. (MedPage Today)