This a video on YouTube shows exactly how the pathology or the changes in the brain happen from a research going to view in Alzheimer's disease and the brain it's a very well made video that is extremely well researched I would urge people who are interested in the subject of dementia loss of memory and similar ideas  to watch it it's on YouTube and it's called mechanism and secrets of Alzheimer's disease exploring the brain

Link and secrets of Alzheimer's disease: exploring the brain