There are couple of good websites in the forum that tell you of the early signs - https://www.healingwell.com/community/default.aspx?f=8&m=548613
My gma's early signs were forgetting names and words for common things. She would stammer and stutter over her words and even then sometimes the correct word would elude her. She also started to lose things constantly or forget where she would put things. Then it sort of escalated to doing odd things and not remembering that she had done it. Such as one time she put safety pins on a pizza that was in a pizza box but denies that it was her that did it. Now she is even forgetting people that she had known for a long time such as an old friend from back home.