I have the same suspicion about his mental state. However, memory loss is not altzeimers. It can be part of that but is not even really indicative. I, for instance, have memory problems and taht's a fact. However, I have been told, by a neurologist that specializes in such that I am not a candidate for altzeimers. My that too had serious memory loss which his wife thought was altzeimer. I sent them both up to Virginia Mason - neither had Altzeimer's.
However, serious memory problems are SERIOUS! You can forget little stuff like your name, where you are at, who you are, etc. You don't have to act out to have memory loss.
Anyway, just saying, one is not necessarily the other. On reflection I don't think you said that either but some might not understand.