Family History - when should testing begin?

Hi everyone.  I'm guessing that a lot of you are on here because you care for family members with this very difficult disease.  On my mother's side her father and his sister had severe Alzheimer's.  My grandfather "had it" (showing symptoms) for about 6 years...the last 2 pretty bad before he passed.  But my Aunt had it for around 12 and had been on Aricept all that time.  My Great Aunt just passed last week at 89 and hasn't known any of us for about 4 years now.

My question is, because of my strong family history (I know it goes back longer than that...and believe there is some history on my father's side as well) when should my mother, especially begin the testing process? She just turned 50 and I want her to do as much as she can.  I also want to be aware for myself in the future - although hopefully there will be a "cure" or something more by then.

thank you all so much

She's actually not showing symptoms at all - I actually think I'm more forgetful than her :) I just remember hearing about studies where they can start testing you and get you on medication sooner than later if they turn out positive for some things? I haven't researched it too much, so I should probably spend some more time doing that.

Thank you!

Wow thank you soo much! They say a 96% accuracy rate - that's amazing and perfect, because I don't think I could get her to go to a doctor, so online will be good. Also to know for myself - I'm only 26 now...but seeing my family go through it - the earlier the better for me!