But there are types of AD that appear to be more related to vascular diseases, than to the insidious internal death of neurons. In fact, there is a famous ongoing study with a group of nuns who have given researchers permission to examine their brains at autopsy as the group dies. There are people in that group who have died, exhibiting the classic symptoms of AD, but when you examine their brains, one sees the cellular wreckage from thousands of tiny strokes. That's why I say there are probably many different kinds of Alzheimer' s, but since their symptoms are so similar, we give them a single name. As you know, paternal twins are no more genetically related to other members of the family than brothers and sisters not of the same age.
AD can progress in a slow fashion or a very fast fashion.
We currently cannot predict the speed currently. There are AD patients who got their diagnosis 20 years ago that are still alive today. Some of the most intractable clinical problems turned out to be easy to solve after small breakthroughs occurred that no one was expecting. Because there are so many different kinds of AD, the hope is that a therapy will be established that will effectively treat the most common types. My aunt with alzheimer's was put on antidepressants about two months ago and her behavior has improved.