I've got something here which may be helpful and/or enlightening for some.
http://www.alzheimer.ca/en/About-dementia/Dementias/What-is-dementia/Seven-A-s-of-dementia
I did find the stages useful in giving a general idea of what was going on with my mother. But dementia is so very individual (as my signature says) that I think it's more about guidelines rather than an exact prognosis. The very nature of dementia is the erratic and unpredictableness of it.
What a useful article, Joanne.
The description of aphasia would have fit John to a T for the first 7 years. He had none of the other symptoms. I have never met or heard of anyone else with just this symptom.
As you say, when you've seen one.......