I have developed poor memory and a degree of face blindness. I have been CRT and MRI scanned, and the scans show my brain is normal. Can I rule out Alzheimer's disease as a cause of my memory loss, or can memory loss occur before observable brain damage? My memory problems have been going on for around 2 years now. With Alzheimer’s patients, how much time would typically elapse after developing memory loss symptoms, would it take for brain scans to show up damage?