CNN Sanjay Gupta MD August 17, 2013 20:40:00
The doctor says he may have found a way using an eye into the brain. >> normally we do not think of an eye an engs r extension of the brain. the back of the eye, the retina, actually developing from the brain itself. so it's brain tissue. >> reporter: a buildup inside the brain can start to develop years before the first symptoms and in fact those same placques develop in eye tissue as well. >> the beauty, a non-invasive repeatable high resolution test to be able to see these protein changes that are the hallmark of alzheimer's disease very early. >> reporter: and joining me now from los angel...