Alzheimer's disease, as we know it, was identified by Dr. Alois Alzheimer in 1906. The disease starts in the brain ten to fifteen years before a patient's symptoms start. When memory loss starts, forty to fifty percent of the brain cells have been affected or destroyed.
The sticky plaques on the brain, which are diagnostic of Alzheimer's disease, are called Beta Amyloid. In recent years, The Food and Drug Administration approved a test called PET Scan to detect Amyloid proteins in the brain. This test is non-invasive. Previous tests included brain biopsy and spinal tap, which are invasive and could be life threatening in some cases.
Research at Cedar Sinai showed that the amount of Beta Amyloid corresponds to the amount of that same protein in the retina. As our bodies develop from an embryo, the retina is formed from the same tissue that makes up the brain.
Developing a non-invasive test to check the retina for Beta Amyloid plaques are in the works. Another company called Cognoptix is testing for Beta Amyloid in the lens of the eye.