Grandmother forgetful, not alzheimers?

I'm just wondering my boyfriend's grandma seems to have Alzheimer's and her doctor thinks it could be, but of course there is no test. She is mostly just very forgetful and repeats herself a lot, like telling the same story again and again and sometimes asking a question she just asked. Other than that she has total comprehension of herself, her surroundings and is very smart. She follows politics and knows what going on, She even knows a little about briney spears being all out of control and when she sees her on a mag cover says she needs to get it together. I just mention that to show how with it she seems to be. The forgetfulness has been this way for at least 2 yrs maybe more. We are starting to think she may just be getting old. How many of you have grandparents that lived a long time with just memory problems that never progressed beyond that?