Aphasia is not a disease, only a symptom, and it can indeed be a symptom of frontotemporal dementia.Does Aphasia lead to dementia? Or possibly misdiagnosed in the first instance?
There are so many cross over symptoms with these kinds of brain disorders that it can be difficult to know.
I don't recall ever hearing of FTD until I saw a thing about it on "60 Minutes" a while back. One of the cruelest things about it is, not so much for the victim as for those who care about them, is that people who have it are not aware that anything is wrong with them.