I'm not. Medical sites don't seem to say that either so far as I can see and so far as a definitive diagnosis goes. (See my response above and link to the Alzheimer's Association.) But you are probably right the same tests are used to diagnose many different brain diseases including other kinds of dementia. Different results on the tests will point to different diagnoses.From what I learned while dealing with both of my parents passing with dementia, what you mentioned is how they would diagnose Lewy Body Dementia. Pretty sure Alzheimer's can be diagnosed through scans.
My sympathy on your losses.
MOO